JPS6243677A - Developing device - Google Patents

Abstract

PURPOSE:To agitate a developer sufficiently with minimum scattering and to easily form a sharp toner image by driving an agitating means and a conveying means for the developer in different sequences. CONSTITUTION:The agitating means 3 of a developing device 2 agitates the developer by rotating in synchronism with the rotation of an image forming body 1 and the developer conveying means 7, on the other hand, conveys a developer layer by the arrow-directional rotation of a sleeve 5 and a magnet body 6 while electrostatic latent image formed on the image forming body 1 passes through a development area 9. Thus, the developer is agitated sufficiently by the long-time rotation of the means 3 and mixed uniformly with a reduced developer and supply toner by a scraping member 10 to eliminate spots of toner density and charge the toner sufficiently and electrostatically. Further, the means 7 conveys the developer layer in a necessary irreducible time. Consequently, sharp images having no fog are easily obtained and the inside of the machine and images are prevented from being stained owing to a toner scatter, etc., to a minimum.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a developing device used in an electrophotographic copying machine, etc., and in particular, the present invention relates to a developing device used in an electrophotographic copying machine, etc. The present invention relates to a developing device NK which has a developer conveying means for conveying a latent image on an image forming body, and develops a latent image on an image forming body using the developer conveyed by the developer conveying means.

[Background of the invention]

In the conventional developing device as described above, especially in an image forming apparatus having a plurality of developing devices such as a multicolor copying machine, both the conveyance of the developer by the developer conveyance means and the stirring by the agitation means are performed on the image forming body. This is done only when developing a baby. The developer stored in such a developing device is a developer with a resistivity of 1, in which magnetic particles are dispersed in or coated with a resin.
08Ω/(・9 or more, average particle size 50μm or less, especially 30
It is said that the development method using a two-component developer consisting of a mixture of a micrometer or less carrier and a toner has good fine line reproducibility and uniformity of solid areas, and enables good multicolor development. (For example, see Japanese Patent Application No. 58-238296). On the other hand, the above-mentioned developer has poor fluidity,
There is a point that it is difficult to stir. For this reason, if the stirring time is short, such as when stirring is performed only when developing a latent image, the replenishment toner and developer will not be sufficiently mixed, resulting in uneven toner concentration in the transported developer. arise or
Frictional charging of the toner is insufficient, and it tends to be difficult to control toner transfer to selectively adhere the toner to the latent image.

In order to solve the above-mentioned problems, increasing the driving time of the developer conveying means and stirring means increases developer scattering, toner adheres to the image forming body surface, stains the image, and increases internal dirt etc. Let's do it.

The resistivity of the developer can be determined by placing the particles in a container with a cross-sectional area of 0.50 cm2 and tapping them, then applying a load of lKf/C1n2 on the particles packed to a thickness of about l■, and 10-105V/cm between bottom electrode
This value is obtained by applying a voltage that generates an electric field, reading the current flowing at that time, and performing a prescribed calculation.The average particle size is measured using a Coulter counter manufactured by Coulter. 1R amount average particle diameter.

[Purpose of the invention]

The present invention has been made based on the above-mentioned findings, and provides a developing device that can easily form a clear toner image by minimizing developer scattering and sufficiently stirring the developer. With the goal.

[Structure of the invention]

The present invention provides a developing device that includes a stirring means that stores a developer containing magnetic particles and stirs the developer, and a developer transport means that includes a magnetic field generating means. The developing device is characterized by being driven in different sequences, and this configuration achieves the above object.

〔Example〕

The present invention will be explained below using illustrated examples.

FIG. 1 is a sectional view showing an example of a developing device according to the present invention, FIG. 2 is a conceptual diagram of an electrophotographic copying machine incorporating the developing device of FIG. 1, and FIG. 3 is a copy of the copying machine of FIG. 2. It is an operation time chart.

In FIG. 1, 1 is a drum-shaped image forming body having a photoreceptor layer on its surface and rotating in the direction of the arrow, and 2 is a developing device.

This developing device! 12, the stirring means 3 rotates in the direction of the arrow to stir the two-component developer in the developer reservoir 4, and the stirring means 3 rotates in the direction of the arrow to stir the two-component developer in the developer reservoir 4. The developer conveying means 7 attracts the developer from the developer reservoir 4 by magnetic force, and rotates the sleeve 5 and the magnet 6 in the directions of arrows opposite to each other to transfer the attracted developer at the same time as the sleeve 5 rotates. The layer thickness of the developer thus transported is regulated on the sleeve 5 by the layer thickness regulating member 8 to form a developer layer, and the developer is transported to the developing area where the sleeve 5 faces the image forming body l. 9, the toner is transferred from the developer layer on the sleeve 5 to the electrostatic image formed on the image forming member 1 to perform development. The developer layer that has passed through the development area 9 is removed from the sleeve 5 by a scraping member 10 made of a magnetic material and returned to the developer reservoir 4, where the toner is reduced by development. is the toner supply means 1 from the toner hopper 11
2. Toner is replenished by 0. Such a developing device 2 is incorporated into an electrophotographic copying machine as shown in FIG. This copying machine includes (1) charging electrode 13;
(2) A step of illuminating the original on the document table 15 with the a-light lamp 14 and irradiating the image forming member 1 with the reflected light to form an electrostatic latent image; (3) Developing the electrostatic latent image with the developing device 2 to form a toner image; (4) Transferring the toner image onto a transfer material P such as recording paper fed by the paper feed roller 16 using the transfer pole 17; , a process of separating the transfer body from the image forming body 1 by the separation pole 18, (5) a process of fixing the toner image on the transfer body P by the fixing device 19, (6) cleaning the surface of the image forming body 1 by the cleaning device @20. A copy of the manuscript is obtained by performing the following steps. This step is performed according to the time chart shown in FIG.

In FIG. 3, image forming body rotation indicates the timing of the rotational drive of the image forming body 1, and the numbers indicate the number of rotations. The charging is based on the timing of uniform charging of the surface of the image forming body 1 by the charging electrode 13,
The exposure lamp is the timing when the lamp 14 is turned on to expose and scan the document surface, and the optical system is the timing when the slit exposure optical system consisting of a mirror and the like that scans and moves together with the exposure lamp 14 is moved. ku indicates return movement. Note that the return movement, which is performed before the movement forward, is a movement for reaching the starting position. The stirring of the developing device 2 is determined by the rotation timing of the stirring means 3, the developer transport is determined by the rotation timing of the sleeve 5 and the magnet body 6, and the developing bias is determined by the timing of the application of the developing bias to the sleeve 5.

Furthermore, the paper feed roller is the timing of the feeding rotation of the paper feed roller 16, the transfer is the timing of discharge for transferring the toner image to the transfer body P by the transfer i17, and the separation is the timing of the transfer body to which the toner image has been transferred to form an image. The timing of static elimination by the separation electrode 18 for separating from the surface of the body 1 is shown.

In this embodiment, the stirring means 3 in the JI4 imager 2 performs stirring by rotating in synchronization with the rotation of the image forming body 1. On the other hand, the developer conveying means 7
While the electrostatic latent image formed on the image passes through the developing area 9, the sleeve 5 and the magnet body 6 rotate in the direction of the arrow in FIG. The long rotation time ensures sufficient agitation of the developer, and the developer is uniformly mixed with the developer reduced by the scraping member 1O and the supplied toner, eliminating unevenness in toner concentration, and the toner is sufficiently charged. It will be held in The developer transport means 7 transports the developer layer for the minimum necessary time. Therefore, it is possible to easily obtain a clear image without fogging, and furthermore, it is possible to minimize internal dirt and image dirt caused by toner scattering and the like. This effect is particularly noticeable compared to conventional developing devices when a two-component developer consisting of a mixture of an insulating carrier and toner having an average particle size of 30 μm or less is used.

Rotating the stirring means 3 of the developing device 2 in synchronization with the rotation of the image forming body 1 means, for example, that only the stirring means 3 is connected to the driving means of the image forming body 1 without a clutch, and the other sleeves are connected to the driving means of the image forming body 1 without a clutch. 5, the magnet body 6, the toner replenishing means, etc. can be easily connected through a clutch.

In the developing device 2 as described above, 70 wt% magnetic particles were dispersed in 30 wt% thermoplastic resin with an average particle diameter of 20 μm.
1 A carrier with a resistivity of 1O15 or more and a pigment of 10 wt% dispersed in a thermoplastic resin of 90 wt% with an average particle size of 10
A two-component developer consisting of a mixture of 4 μm toner by weight is stored, and the developer layer on the sleeve 5 is transferred to the image forming body 1 in the state where no electric field is generated in the upper image area 9. The original is formed in a thick layer so as not to contact the surface of the original, and a developing bias consisting of an appropriate alternating current voltage, direct 5 tr, and 71 pressure is applied to the sleeve 5 in accordance with the copying operation shown in FIG. 3. When the image was copied, it was possible to easily obtain a stable, clear copy image with no fog, and there was little occurrence of stains due to toner scattering.

〔Effect of the invention〕

According to the present invention, the developer is uniformly stirred and the toner is sufficiently charged, and the toner transfer control by the development bias is facilitated.Therefore, clear development without fog can be performed, and the toner can be sufficiently charged. This has the effect of reducing the occurrence of dirt inside the machine due to scattering of the agent. Especially as a developer,
This effect is significant when a mixture of toner and insulating carrier of small particle size is used. In addition, the drive transmission mechanism of the developing device can be configured at low cost, and its lifespan can be extended.

Although the embodiment shows a case where the rotation of the developer stirring means is synchronized with the rotation of the image forming body, the present invention is not limited to this, and the stirring means may be driven in a different sequence from the developer conveying means. Sufficient stirring may be performed.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the developing device according to the present invention, FIG. 2 is a conceptual diagram of an electrophotographic copying machine incorporating the developing device of FIG. 1, and FIG. 3 is a schematic diagram of the copying machine of FIG. 5 is a copying operation time chart. l...image forming body, 2...developing device, 3...
- Stirring means, 4...Developer reservoir, 5...
Sleeve, 6... Magnet, 7... Developer transport means, 8... Layer thickness regulating member, 9... Development area,
10... scraping member, 11... toner hopper, 12... toner supply means. Patent applicant: Konishiroku Photo Industry Co., Ltd. Figure Z

Claims (2)

[Claims] (1) In a developing device having a stirring means for storing a developer containing magnetic particles and stirring the developer, and a developer conveying means including a magnetic field generating means, the stirring means and the developer conveying means are A developing device characterized in that it is driven in different sequences. (2) The developing device according to claim 1, wherein the developer comprises a mixture of a magnetic carrier having a resistivity of 10^8 Ω/cm or more and an average particle size of 50 μm or less, and a toner having an average particle size of 20 μm or less.