JPH0619631B2 - Development device - Google Patents

Description

Description: TECHNICAL FIELD The present invention has a developer carrier that carries and conveys a one-component developer that visualizes an electrostatic latent image formed on a latent image carrier to a developing area. The carrier comprises a conductive layer and a plurality of microelectrodes electrically insulated from the conductive layer and electrically insulated from each other, and at least a part of the microelectrodes carries a developer. The present invention relates to a developing device exposed on the surface of the body.

According to the developing device of the above type used in an image forming apparatus such as an electronic copying machine or a printer, when a one-component developer containing no carrier is used instead of a two-component developer containing carrier and toner. Also, an effective edge effect can be obtained at the time of image formation, and it is possible to reproduce a narrow line-shaped original image, that is, a line image and a plane solid image in a state matching each request (for example, JP 57-
114163).

This is an effect obtained by a large number of electrically conductive floating microelectrodes, but it is most common to use metal particles for these microelectrodes. However, when the microelectrodes made of metal particles are exposed to the developer carrying member, the amount of the developer carried on the carrying member to the developing area while being carried on the carrying member becomes smaller than the originally required amount. There is a possibility that the quality of the formed visible image may deteriorate.

Object An object of the present invention is to provide a developing device capable of transporting a required sufficient amount of developer to a developing area without losing the original function of the microelectrode and further improving the quality of a visible image. To provide.

Configuration To achieve the above object, the present invention proposes a configuration in which particles in which a conductive substance is dispersed are used as microelectrodes in a developing device of the type described at the beginning.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a main part of an electronic copying machine equipped with a developing device according to the present invention. In a tank 1 of the developing device, a one-component developer, in this example, a one-component non-magnetic developer. 2 (hereinafter,
Non-magnetic toner, or simply referred to as toner) is contained. The toner 2 in the tank 1 is agitated by an agitator 3 and is developed by a toner supply roller 4 which is rotationally driven counterclockwise as a developing sleeve 5 which rotates counterclockwise while being in contact with the roller 4. It is supplied to the agent carrier (arrow A). The structure of the developing sleeve 5 will be described later in detail.

The toner supplied to the surface of the developing sleeve 5 is carried while being carried on the sleeve surface as the sleeve 5 rotates, and at that time, the toner is uniformly regulated to a predetermined thickness by the layer thickness regulating member 6.

The toner on the developing sleeve 5 that has passed through the layer thickness regulating member 6 forms a toner layer having a predetermined thickness, and at that time, for example, due to friction with the layer thickness regulating member 6, it is charged to a predetermined polarity, for example, positive. Therefore, when this toner layer reaches the latent image carrier running in the direction of the arrow B, that is, the developing area C facing the photoconductor 7 in this example, it is electrostatically transferred to the electrostatic latent image formed on the photoconductor 7. Then, the latent image is visualized.

As described above, the developing sleeve 5 carries and conveys the toner, which visualizes the electrostatic latent image formed on the photoconductor 7, to the developing area C. The sleeve 5 has a conductive layer 8 which also serves as a core, as schematically shown in FIGS. 1 and 2.
It has an insulating layer 9 laminated thereon and an electrode dispersion layer 11 further laminated thereon. The dispersion layer 11 is made of an insulating material such as epoxy resin and has a large number of conductive microelectrodes 10.
Is dispersed. Therefore, the microelectrodes 10 are insulated from each other and also insulated from the conductive layer 8, and are in an electrically floating state.

When the developing sleeve 5 having the microelectrodes 10 is used, an effective edge effect can be obtained when a latent image is visualized, even if a one-component developer is used as the developer, and particularly the development efficiency of a line latent image is improved. Can be increased. FIG. 3 is a graph showing the image density of the original to be copied on the horizontal axis and the density of the visible image obtained on the vertical axis. When an original image is a narrow line image, for example, a character image, , A high density visible image is desired even when the density is low, as indicated by a broken line X, and conversely, a solid image of a plane form a visible image having a density corresponding to the density of the original image as indicated by a solid line Y. It is usual to want to obtain the image, and a developing device using microelectrodes can form a visible image that meets or corresponds to this requirement. The principle is disclosed in detail in Japanese Patent Application Laid-Open No. 57-114163, etc., which has already been described above, and the description thereof is omitted here.

By the way, in order to enhance the function of the microelectrodes 10, it is advantageous to expose at least a part of the microelectrodes 10 to the surface of the developing sleeve 5 and bring the electrodes 10 closer to the photoreceptor as shown in FIG. However, as described above, when metal particles such as copper particles are used as the microelectrodes and exposed on the sleeve surface, the amount of toner carried on the sleeve 5 may be insufficient.

Therefore, in the structure according to the present invention, each microelectrode 10 is formed as illustrated below. That is, as schematically shown in FIG. 4, a conductive substance such as carbon black or metal powder is dispersed in an insulative resin, such as an epoxy resin, and this is dispersed in, for example, 60 to 150.
The particles are pulverized to about μ and used as the microelectrode 10. Such particles are entirely conductive,
By dispersing these in the insulating material of the electrode dispersion layer 11 as shown in FIG. 2, the microelectrode 10 can be used without any trouble. Moreover, although the microelectrode 10 is exposed on the surface of the sleeve 5,
The required amount of toner is applied and this is applied to the development area C.
It is possible to prevent the deterioration of the image quality of the visible image due to the shortage of the toner amount.

The reason why the amount of toner adhered to the developing sleeve 5 can be increased as described above is not clear, but it is considered as follows.

Since the toner is made of resin, it is difficult for the toner to adhere to the fine electrodes of metal particles directly exposed on the sleeve surface. However, if the microelectrode 10 contains resin as shown in FIG. 4,
Similarly, the toner made of the resin comes into contact with the minute electrodes made of the resin so that the resins come into contact with each other, so that the toner easily adheres to the minute electrodes.

As described above, the fact that a large amount of toner can be carried on the developing sleeve 5 and conveyed to the developing area C has been confirmed by many experiments.

As a resin that disperses a conductive substance such as carbon black, an appropriate resin such as acryl or urethane can be used in addition to an epoxy resin, and also as an insulating substance of the electrode dispersion layer 11 that disperses microelectrodes. , Epoxy resin, acrylic, urethane, acrylic-urethane,
A wide range of resins such as epoxy-silicon type and epoxy-Teflon type can be appropriately used. However, in the triboelectrification series, a resin separated from the toner is used, the toner is also charged by the developing sleeve 5, or charged by the layer thickness regulating member 6. It is desirable to consider that the charged state of the formed toner does not become an undesired state.

In order to manufacture the developing sleeve shown in FIG. 2, an insulating resin in which carbon black, metal, etc. are dispersed, for example, an epoxy resin is crushed to make particles (FIG. 4), and these particles are further dispersed in the resin. After being evenly dispersed, this is applied from above the insulating layer 9 laminated on the core material of the conductive layer 8, and after hardening this, the outer peripheral surface is polished and the developing sleeve 5 as shown in FIG. To get Alternatively, for example, an epoxy resin is applied on the conductive layer 8 or the insulating layer 9 laminated thereon,
Alternatively, the particles may be directly and evenly dispersed thereon, and the particles may be fixed, and then the peripheral surface thereof may be polished.

If an insulating resin overcoat layer is further laminated on the electrode dispersion layer 11, even if metal particles are used as the microelectrodes, the surface of the particles is resin, so that the toner adhesion amount can be prevented from being insufficient. However, it is necessary to make the thickness of the overcoat layer extremely thin so as not to impair the effect of the microelectrode, and it is not easy to coat such a thin layer with a uniform thickness, and the developing sleeve Inevitably suffers from the drawback of rising costs. According to the developing sleeve 5 shown in FIG. 2, such a defect can be prevented.

The insulating layer 9 shown in FIG. 2 is for adjusting the dielectric thickness from the conductive layer 8 to the photosensitive member 7 (FIG. 1) and for adjusting the strength of the electric field formed between them. In some cases, the insulating layer may be omitted as shown in FIG.

Further, the conductive layer 8 does not necessarily have to be the core material of the developing sleeve 5, and for example, a cylindrical core material 14 may be provided below the conductive layer 8 as shown in FIG.

The developing sleeve 5 may be a rigid body as a whole, but at least a part thereof, for example, FIGS. 2, 5, and 6 may be used.
If at least one of the layers shown in the figure is made of an elastic body, the contact between the developing sleeve 5 and the photoconductor 7 can be made smooth, and the inconvenience of damaging the photoconductor can be more reliably prevented.

For example, the resin used for the electrode dispersion layer 11 is made an elastic epoxy resin to soften it, or the insulating layer 9 is made of rubber such as chloroprene rubber, foam, sponge, elastic body such as elastic resin, and shown in FIG. The core material 14 can also be made of an elastic material such as elastic rubber, foam, or elastic epoxy resin.

The present invention can also be applied to a developing device using a magnetic one-component developer (magnetic toner), in which case a magnet is fixedly or rotatably provided in the developing sleeve and at least one of the sleeve and the magnet is rotated. It drives to convey toner. Alternatively, a fine magnetized magnet called a rubber magnet or a plastic magnet is provided integrally with the sleeve,
This may be rotationally driven. Even when the magnet is integrally provided on the sleeve as in the latter case, the microelectrode according to the present invention can be used without any trouble.

As described above, the configuration in which various magnets are provided may be adopted in order to make the regulating member a magnetic body, attract this by a magnet, and evenly press the regulating member against the developing sleeve even when non-magnetic toner is used. it can.

When a developing sleeve having the microelectrodes 10 is used, the latent image charges on the photoconductor 7 may cause electric charges to be accumulated in the microelectrodes. If this is left, the image quality of a visible image is deteriorated. In the embodiment shown in FIG. 1, a power source 13 for applying a bias voltage to the developing sleeve 5 is connected to the static elimination brush 12 and the regulating member 6, and these members 12, 6 are connected.
The static electricity is removed from the microelectrode 10 or the insulating material around it.

The present invention can be widely applied to a developing device having a developer carrying member composed of a belt, a developing device other than an electronic copying machine, and the like.

Effect According to the present invention, since the microelectrodes of the developer carrier are composed of particles in which a conductive substance is dispersed in a resin, the one-component developer is attached to the microelectrodes exposed on the surface of the developer carrier. It becomes easier, and a required amount of developer can be conveyed to the developing area, whereby a high-quality visible image can be formed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a developing device according to the present invention, FIG. 2 is an enlarged sectional view schematically showing a developing sleeve, and FIG.
FIG. 4 is a graph for explaining the effect of the microelectrode, FIG. 4 is an enlarged schematic view of the microelectrode, and FIGS. 5 and 6 are sectional views similar to FIG. 2, showing another embodiment. 2 ... Developer, 8 ... Conductive layer 10 ... Microelectrode, C ... Development area

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hidetoshi Yano 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Rybun Kiyomiya 1-3-6 Nakamagome, Ota-ku, Tokyo Shares Within Ricoh Company (56) Reference JP-A-57-114163 (JP, A) JP-A-58-72968 (JP, A)

Claims (1)

[Claims] 1. A developer carrier for carrying and transporting a one-component developer for visualizing an electrostatic latent image formed on a latent image carrier to a developing area, the carrier being a conductive layer. And a plurality of microelectrodes electrically insulated from the conductive layer and electrically insulated from each other, and at least some of the microelectrodes are exposed on the surface of the developer carrier. In the developing device, the microelectrode is made of particles in which a conductive substance is dispersed in a resin, the developing device.