JPS647664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for developing a latent image with a developer, and more specifically, it relates to a device for developing a latent image with a developer, and more specifically, a device for regulating a magnetic developer (hereinafter referred to as magnetic toner) to an appropriate thickness and a developer supporting device. The present invention relates to a developing device having means for easily maintaining a constant distance, and means for maintaining a constant distance between a latent image holding means and a developer supporting means.

Conventionally, methods employed in developing devices for electrophotography and electrostatic recording are broadly classified into dry developing methods and wet developing methods. The former method is further divided into methods using a two-component developer and methods using a single-component developer. Two-component developing methods include the magnetic brush method using an iron powder carrier, the cascade method using a bead carrier, and
There is a fur brush method using fur, etc. Furthermore, the one-component development methods include the powder cloud method, in which toner particles are sprayed, and the contact development method, in which toner particles are brought into direct contact with the electrostatic latent image surface. (also called donor development), jumping development method in which toner particles are not brought into direct contact with the electrostatic latent image surface, but are charged and flown toward the latent image surface by the electric field of the electrostatic latent image; magnetic conduction There is the MagneDry method, which develops by bringing a toner into contact with the electrostatic latent image surface.

Two-component development methods inevitably use a developer mixture of carrier particles and toner particles, and as the development process normally progresses, toner particles are consumed in far larger quantities than carrier particles, so the mixing ratio of the two changes. However, they inherently have drawbacks such as fluctuations in the density of the visible image and deterioration of image quality due to deterioration of carrier particles that are difficult to consume due to long-term use.

On the other hand, in one-component developing methods, the Magne-Dry method using magnetic toner and the contact developing method without magnetic toner, the toner contacts the entire surface of the surface to be developed, that is, both the image area and the non-image area. However, there was a problem in that toner easily adhered even to non-image areas, resulting in so-called background fog and dirt.
(This problem of fog staining was also a drawback in two-component development methods.) Also, in the powder cloud method, it is inevitable that powdered toner particles adhere to non-image areas. Similarly, it had the disadvantage that background fog could not be removed.

Furthermore, in the so-called jumping development method, which belongs to the one-component development method, toner is uniformly applied to a carrier such as a sheet, and then the toner is opposed to an electrostatic image holding surface with a small gap, so that the electrostatic charge is removed from the toner carrier. A method is known in which toner is attracted and adhered to the image holding surface by the electric charge of the electrostatic image (Japanese Patent Publication No. 1973-
9475, U.S. Patent No. 2839400, etc.). This method has the advantage that not only the toner is not attracted to the non-image area where there is no static charge, but also the toner and the non-image area do not come into contact with each other, so that the above-mentioned fogging is less likely to occur. In addition, since carrier particles are not used, there is no variation in the mixing ratio as described above.
Furthermore, there is no deterioration of carrier particles.

However, this method has not yet been put into practical use due to various drawbacks described below.

It has been difficult to apply the developer uniformly to the developer support means in a practical manner, and it has also been difficult to apply and maintain the developer onto the developer support means without agglomerating the developer after repeated use. This point has become practically possible by a method of coating the developer on a developer supporting means using a developer thickness regulating means (hereinafter referred to as a magnetic blade) made of a magnetic material or a magnet (see Japanese Patent Application No. 109240/1982).

Furthermore, the so-called jumping development method tends to have high γ characteristics and poor tone reproducibility. This point has also been improved by applying a low frequency AC voltage as a developing bias between the developer support means and the electrostatic latent image support means (Japanese Patent Application No. 53-92105, etc.).
Specifically, there are the following problems.

The gap between the developer support means and the magnetic blade must be set with high accuracy, and this gap must be maintained. However, this gap cannot be kept constant due to temperature changes due to the environment, and the thickness of the developer on the developer supporting means decreases significantly at low temperatures, resulting in a problem of lowering the developed density.

In addition, because the gap between the developer support means and the magnetic blade is narrow, dust such as paper dust accumulates in this area, which hinders the application of the developer on the developer support means, resulting in insufficient supply of developer to the developer coating layer. White streaks may appear. In order to remove dust such as paper powder, it is necessary to remove the magnetic blade and adjust and set it again. During this setting, if the magnetic blade is pulled by the magnet provided on the back side of the developer support means and comes into pressure contact with the developer layer on the developer support means, agglomeration of the developer layer occurs, and this agglomerated development occurs. Not only does the agent not contribute to development and cause problems, but it also accumulates in the gap between the magnetic blade and the developer support means, which may impede the application of the developer onto the developer support means. For this reason, it is required to be able to easily maintain and reset a predetermined distance between the developer support means and the magnetic blade without causing any agglomeration of the developer coating layer on the developer support means.

It is an object of the present invention to eliminate these conventional drawbacks and provide a developing device with high fidelity and stable image quality. Specifically, the present invention has the following features: (1) The distance between the magnetic blade and the developer support means can be maintained well even with changes in environmental temperature, and the developer can be coated with a stable thickness on the developer support means. A layer is obtained and a stable development is obtained.

(2) The gap between the developer support means and the magnetic blade can be reset with constant precision without causing the developer coating layer on the developer support means to aggregate.

The purpose is to

To achieve the above object, the present invention includes a developer supporting member that supports and transports developer to develop a latent image, a magnetic field generating means provided inside the developer supporting member, and a magnetic field generated by the magnetic field generating means. a thickness regulating member having magnetism that is provided facing the developer supporting member and regulating the thickness of the developer layer on the developer supporting member; and a thickness regulating member that is provided coaxially with the developer supporting member and that generates the magnetic field. The developing device includes a position setting member that is brought into contact with an end portion of the thickness regulating member on the side of the developer supporting member that is magnetically drawn toward the developer supporting member by a means.

This will be explained below using examples.

FIG. 1 shows a member that allows the distance between the developer support means and the magnetic blade to be set to a predetermined value, and the distance between the developer support means and the latent image support means in an embodiment of the developing device according to the present invention. A member is shown that allows setting the value to a predetermined value. Of course, it is not limited to this example. In this figure, reference numeral 1 denotes a developer support means, which has a position setting member 2 coaxially with the rotating shaft 1a for easily setting the distance between the developer support means and the magnetic blade to a predetermined value. Reference numeral 3 denotes a distance setting member which is attached coaxially with the shaft 1a of the developer support means and sets the distance between the developer support means 1 and the latent image support means to a predetermined value.

FIG. 2 shows one embodiment of the developing device according to the present invention. In the figure, 1 indicates the developer supporting means shown in FIG. A magnet roll 11 (Fig. 3) is contained in this. Reference numeral 6 indicates a developing roller that is a combination of these two. The developer supporting means 1 is rotated in a direction following the photosensitive drum at approximately the same peripheral speed as the photosensitive drum by the gear 5 that meshes with the drive gear 13 (FIG. 4) of the photosensitive drum 12, which is a latent image support. As shown in FIG. 1, 2 is a position setting member that easily sets the distance between the developer support means and the magnetic blade to a predetermined value, and in this case, the function of the bearing member of the developing roller 6 is It has been modified to have . Reference numeral 4 denotes a magnetic blade which is a means for regulating the thickness of the developer on the developer support means 1, and this magnetic blade is located within the magnetic field generated by the magnet 11 (Fig. 3). The thickness of the magnetic developer layer on the developer support means 1 is regulated to be less than or equal to the distance between the developer support means 1 and the photosensitive drum 12. The magnetic blade 4 is magnetically drawn in the direction of the developer support means 1 by the magnet 11, and its end on the developer support means side is connected to the developer support means 1 and the magnetic blade 4 as shown in the figure. It rests on means 2 for setting the spacing to a predetermined value. The distance between the magnetic blade 4 and the developer supporting means 1 is, for example, a minute value of 200 μm. The width of the magnetic blade 4's movement in the horizontal direction is restricted by the screw 7, but it is possible to move in the direction of arrow P (vertical direction) shown in Fig. 3, and it can be fixed to the main body. It has not been. 15 is a hopper that supplies developer. Changes in the distance between the developer support means 1 and the magnetic blade 4 due to temperature changes in the environment are as follows:
In the developing device according to this embodiment, the developer supporting means 1
and thermal expansion from the bearing hole of the developing roller 6 in the member 2 that sets the distance between the developer support means and the magnetic blade 4 to a predetermined value to the tip position of the magnetic blade 4, that is, the position that supports the magnetic blade 4. The tip of the magnetic blade 4, which is magnetically drawn by the magnet 11, is positioned in contact with the member 2 which is coaxial with the developer support means 1, so that the heat is removed. The effect of expansion is small. For example, when the distance between the magnetic blade 4 and the developer support means 1 is constant and the constituent materials are constant, the farther the magnetic blade 4 is fixed from the developer support means 1, the more the developer support means 1 due to thermal expansion. The amount of change in the distance between the magnetic blade 4 and the magnetic blade 4 is large.

As shown in FIG. 1, 3 is a means (hereinafter referred to as abutting roller) for maintaining a constant distance between the developer supporting means 1 and the latent image holding means, and is driven by the photosensitive drum 12, which is the latent image holding means. and move. Hitting roller 3
is applied to the latent image holding means as shown in FIG. 4, for example. FIG. 4 shows one example of the structure of the embodiment. In FIG. 4, 8 is a cylinder of a photosensitive drum which is a latent image support, and 9 is a cylinder of CdS.
It is a photosensitive layer. Further, 10 is an electrically insulating layer on the photosensitive layer. Further, as shown in FIG. 5, 14 is a sealing member such as felt, which prevents the developer from entering the bearing portion.

As explained above, in a developing device using a magnetic developer, the distance between the magnetic blade and the developer supporting means can be maintained well even when the temperature changes in the environment, and the distance between the magnetic blade and the developer supporting means can be kept stable. The magnetic blade can be easily set by maintaining a predetermined distance between the developer support means and the magnetic blade, and a good and stable developer coating layer can be obtained at all times. A latent image developing device using magnetic toner that provides a stable visible image can be provided.

Furthermore, the developing device according to the present invention can be applied not only to developing electrostatic latent images, but also to devices for developing latent images of other properties, such as magnetic latent images, using a magnetic developer.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of a developing roller applied to the developing device according to the present invention, FIG. 2 is a perspective view of one embodiment of the developing device according to the present invention, and FIG. 3 is a sectional view thereof. FIG. 4 is a front view of the developing device facing the latent image carrier, and FIG. 5 is a partially enlarged sectional view of the end thereof. 12... Latent image holding means, 1... Developer supporting means, 3... Spacing setting member, 15... Means for supplying developer, 11... Magnetic field generating means, 4... Means for regulating thickness, 2 ...Position setting member.

Claims (1)

[Scope of Claims] 1. A developer supporting member that supports and transports developer to develop a latent image, a magnetic field generating means provided inside the developer supporting member, and a developing device in a magnetic field generated by the magnetic field generating means. a thickness regulating member having magnetism that is provided facing the developer and regulating the thickness of the developer layer on the developer supporting member; and a magnetic field generating means that is provided coaxially with the developer supporting member. a position setting member that is brought into contact with an end portion of the thickness regulating member on the developer support member side that is magnetically drawn toward the developer support member by the developer support member; 2. The developer is a magnetic developer, and the thickness regulating member controls the thickness of the developer layer to be equal to or less than the distance between the latent image carrier holding the latent image and the developer support member in the magnetic field generated by the magnetic field generating means. A developing device according to claim 1 of the regulatory claims.