JPS61141469A - Developing device - Google Patents

Abstract

PURPOSE:To maintain good image quality even in a developing method in which a carrier is charged first into a developing device and a toner is afterward charged therein by using a sleeve having multiple magnetic poles. CONSTITUTION:The sleeve 8 is the magnetic multipolar sleeve which is rotatable and is enclosed of magnetic power on the circumference having alternately many N poles and S poles and the magnetic lines of force of high density are released from the surface of the sleeve 8. A main pole magnet 9 is provided in the sleeve 8 and the width of the magnetic pole of the magnet 9 is larger than the width of each magnetic pole of the sleeve 8 and has, for example, the width of several times the width in the circumferential direction of each magnetic pole of the sleeve 8. The carrier 10 is first charged and the chain-like ears of the carrier 10 are formed over the entire surface of the sleeve 8 in the case of using the magnetic multipolar sleeve 8, then the magnetic force acting on the carrier 10 existing on the sleeve 8 is strong and the amt. of the carrier 10 is made constant regardless of the amt. of the toner 11 to be charged, by which the toner concn. in the developing region is maintained constant.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a developing device used in an electrophotographic copying device, etc., and particularly to a developing device for developing an electrostatic latent image on a photoreceptor to obtain a copied image of a document. The invention relates to a developing device.

[Prior art]

At present, developing devices for electrophotographic copying apparatuses include those that use a magnetic brush made of a dry developer, and those that use a one-component developer and those that use a two-component developer. In a developing device using a one-component developer, for example, an insulating toner is used, and the toner is attracted to an electrostatic latent image on a photoreceptor by frictional charging with other members or charge injection. Further, in a developing device using a two-component developer, toner and carrier are triboelectrically charged to cause the toner to be attracted to the electrostatic latent image.

FIG. 2 is a diagram showing the configuration of a conventional developing device and its vicinity. The carrier 5 is charged into the developer hopper 4 in advance, and the carrier 5 is attached to the entire circumferential surface of the sleeve 3.Then, the toner 6 is introduced and the toner 6 is attached to the upper surface of the carrier 5, and the attached toner 6 causes the photoconductor to be This is for developing the electrostatic latent image on drum l.

[Problems with conventional technology]

In the conventional developing device 2 as described above, the carrier 5 is charged first, and each magnet 7a, 7b is loaded.

7c, 7d Although the magnetic force forms spikes of the carrier 5 on the sleeve 3, the magnetic force appearing on the non-magnetic sleeve 3 is weak. Therefore, when the doctor blade 4a is used to cut the ears near the magnet 7d, the carrier 5 is cut into the sleeve 3.
This makes it difficult to continue developing with the carrier 4 wrapped around the sleeve 3. For this reason, when pressure is applied to the carrier 5 in which the toner 6 put into the developing device 2 stands in spikes, the toner 6 does not stand in spikes even if the toner 6 itself contains or contains magnetic material. He got into the middle of Carrier 5.

The toner concentration on the sleeve 3 gradually increases, causing deterioration of image quality.

[Object of the Invention] In view of the above-mentioned conventional drawbacks, the present invention provides a method of maintaining good image quality even in a developing method in which carrier is first introduced into the developing device and toner is subsequently introduced by using a multi-magnetic sleeve. The object of the present invention is to provide a developing device that enables the following.

[Key points of the invention]

According to the present invention, the above object is a rotatable multi-magnetic pole sleeve in which N poles and S poles are arranged alternately in the circumferential direction, and the circumference is surrounded by magnetic powder.

This is achieved by providing a developer characterized in that it has a developer pole fixedly disposed within the multi-pole sleeve.

[Embodiments of the invention]

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

FIG. 3 is a structural diagram of the sleeve and main pole magnet used in the developing device of the present invention. In the figure, the sleeve 8 is a multi-magnetic sleeve having a large number of N-pole and S-pole magnetic poles alternately on its surface, and high-density lines of magnetic force are emitted from the surface of the sleeve 8.

The main pole magnet 9 is provided inside the sleeve 8, and the main pole magnet 9 is
The width of the magnetic pole of the main pole magnet 9 is wider than the width of each magnetic pole of the sleeve 8, for example, several times the width of each magnetic pole of the sleeve 8 in the circumferential direction. In FIG. 4, the sleeve 8 having such a structure is rotated.

7 is a diagram showing the direction of magnetic lines of force and the density of lines of magnetic force when sleeve 8 is positioned on main pole magnet throat 9. FIG.

In the area where the magnetic poles on the surface of the sleeve 8 are the same as the magnetic poles of the main pole magnet 9, high-density lines of magnetic force are generated perpendicularly to the sleeve 8. For example, if the magnetic pole of the main pole magnet 9 is the N pole,
In areas 8d and 8f where the surface of the sleeve 8 is the north pole, high-density lines of magnetic force are induced to the outside.

Sleeve 8 having the above structure. The operation during development in the developing device having the main pole magnet 9 will be described below.

First, the carrier 10 is put into the developing device, and the carrier 10 is attached to the magnetic pole on the surface of the sleeve 8 described above. The amount of carrier 10 thrown in at this time is sufficient to uniformly cover the surface of the sleeve 8, and is deposited on the sleeve 8 as shown in FIG.

That is, the ears formed by the carriers 10 form a dense chain of the carriers 10 on the sleeve 8 and hardly stand up in the ears, and therefore a thin layer of carriers 10 is formed on the sleeve 8. Become. This layer of the carrier 10 is a thin layer, and since the magnetic force of the sleeve 8 acts directly and strongly, it is not removed from the sleeve 8 during ear cutting with a doctor blade.

After the carrier 10 is put into the developing device, the toner 11 is put into the developing device. Even if pressure is applied to the carrier lO on the sleeve 8 from above the charged toner 11, the carrier lO from the sleeve 8
Since the magnetic force acting on the carrier 10 is strong, the carrier 10 will not separate from the sleeve 8.

Next, the toner 11 is adsorbed to the carrier 8 layer formed in a concave shape on the sleeve 8 in this manner.

As the sleeve 8 rotates, the surface of the photosensitive drum on which an electrostatic latent image corresponding to the document is formed is rubbed.

At this time, since the sleeve 8 has moved to the position where the main pole magnet 9 is present, the high-density lines of magnetic force as explained in FIG. Unlike the carrier 10 that stands up as a spike due to a weak magnetic force as shown in FIG. 6, the stiff carrier 10 stands up as a spike due to the strong magnetic force as shown in FIG. located in a certain shape. Therefore, when rubbing against the photoreceptor drum.

The toner 11 can be efficiently attached to the photosensitive surface,
A toner image of sufficient density is formed on the photosensitive surface.

As described above, when using the multi-pole sleeve 8, if the carrier 10 is introduced first and a chain-like spike of carrier lO is formed on the entire surface of the sleeve 8, the carrier 10 on the sleeve 8
The magnetic force acting on 0 is strong.

Furthermore, the amount of carrier lO remains constant regardless of the amount of toner 11 added. Therefore, by controlling the amount of toner 11 that adheres to the sleeve 8 using a doctor blade or the like and keeping the amount of developer conveyed to the developing area constant, the toner concentration in the developing area can be kept constant. Become. Therefore, if the potentials are the same, the toner 11 attracted to the photosensitive surface
The amount of image is also constant, and the quality of the image is good.

Further, according to the second embodiment, since the carrier 1o is almost fixed on the multi-pole sleeve 8, the sleeve 8
Frictional charging between the toner 11 and the carrier 10 in the vicinity is sufficiently performed, and the toner 11 having a stable charge is attracted to the photosensitive surface. Therefore.

It is also possible to prevent development troubles caused by the toner 11 being charged more than the appropriate amount.

In addition, conventionally, if the distance between the main pole magnet 9 and the sleeve 8 is not as short as possible, the spikes of the carrier 10 and toner 11 will be low and the image quality will be reduced. In contrast, by using the sleeve 8 of the present invention, even if the distance between the main pole magnet 9 and the sleeve 8 is somewhat widened, the state of spike formation can be maintained. Almost no change. In other words, it is possible to always form a substantially constant ear even when the sleeve 8 is eccentric.
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The embodiments of the present invention are not limited to the above, and the toner used in the present invention is not limited to non-magnetic toner, but may be configured using magnetic toner. Further, under the condition that the width of the main pole magnet 9 is wider than the width of each magnetic pole provided on the sleeve 8, the width of the main pole magnet 9 is changed, and the width of the magnetic poles on the surface of the sleeve 8 is changed. , the number of spikes, height, width, etc. of the carrier 10 and toner 11 may be changed.

〔Effect of the invention〕

As described above in detail, according to the present invention, the carrier on the sleeve is strong in the developing section.

By forming tall spikes, the toner on the carrier is efficiently attracted to the electrostatic latent image on the photosensitive surface, making it possible to obtain a good image. In addition, the carrier forms a chain-like thin layer on the sleeve in areas other than the developing area, so toner does not get between the carriers, and after passing through a doctor blade etc., a certain amount of toner adheres to the carrier. be able to. Furthermore, the toner is not overly charged, and the positional relationship between the sleeve and the main pole magnet does not require much precision.

It becomes possible to design and manufacture the developing device relatively easily.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing a state in which carrier and toner stand on the sleeve near the main pole magnet in the developing device of the present invention, Fig. 2 is a configuration diagram of a conventional developing device, and Fig. 3 shows the sleeve and toner. FIG. 4 is a configuration diagram of the main pole magnet, and FIG. 4 is a configuration diagram explaining the distribution of magnetic lines of force. FIG. 5 is a configuration diagram showing a state in which carrier is formed in a chain shape on the sleeve of the developing device of the present invention, and FIG. 6 is a configuration diagram showing a state in which carrier and toner stand in spikes on the sleeve of a conventional developing device. It is a diagram. 8...Sleeve, 9...Main pole magnet
10...Carrier, 1]... Toner. Patent applicant Casio Computer Co., Ltd. Same as above
Casio Electronic Industries Co., Ltd. Patent Attorney Dai
Yoshiyuki Suga Figure 1 Figure 2 Figure 3 Figure 4

Claims (4)

[Claims] (1) A rotatable multi-magnetic pole sleeve in which N poles and S poles are arranged alternately in the circumferential direction and the circumference is surrounded by magnetic powder; A developing device characterized by having a developing magnetic pole. (2) The circumferential width of each magnetic pole of the multi-pole sleeve is:
2. The developing device according to claim 1, wherein the width in the circumferential direction of the developing magnetic pole is narrower than that of the developing magnetic pole. (3) The developing device according to claim 1 or 2, wherein magnetic toner is used as the developing toner of the developing device. (4) A non-magnetic toner is used as the developing toner of the developing device; or
Developing device according to item 2.