JPH0210540Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a magnetic brush device in an electronic copying machine that performs copying using a developer.

Generally, in an electronic copying machine, a developer made of a mixture of a magnetic carrier and toner is attached to a magnetic roller to form a magnetic brush, and the toner in the developer is applied to the surface of a photosensitive drum by this magnetic brush. Some types include a developing section or a cleaning section for removing toner remaining on the surface of the photosensitive drum after transfer using a magnetic brush as described above.

In the developing section or cleaning section of such an electronic copying machine, in order to uniformly apply developer toner to the surface of the photosensitive drum and to effectively remove residual toner from the surface of the photosensitive drum, , equipped with a developer stirring device.

However, since conventional developer stirring devices simply stir the developer within the case of the developing section or cleaning section, they cannot scrape off the developer adhering to the surface of the magnetic roller. For this reason, a scraping plate is required to scrape off the developer from the surface of the magnetic roller, which not only complicates the device but also poses a risk of developer becoming clogged between the scraping plate and the case. Since it is necessary to prevent the developer from clogging, there is also the drawback that the entire device becomes larger.

In addition, although the developer stirring device described above can move the developer in the axial direction (longitudinal direction) of the magnetic roller, it cannot move much in the rotational direction of the magnetic roller. The developer cannot be sufficiently attached to the surface of the machine, and therefore it is necessary to use an impeller or the like to stir the developer in the circumferential direction, which has disadvantages such as complicating the equipment and increasing costs. Ta.

This invention was made in consideration of the above points, and its purpose is to be able to effectively scrape off the developer from the surface of the magnetic roller without using any scraping plate. Moreover, it is an object of the present invention to provide a magnetic brush device equipped with a developer stirring device that can satisfactorily stir scraped developer in the axial and rotational directions.

An embodiment of this invention will be described below with reference to FIGS. 1 and 2. FIG. 1 shows a developing section of an electronic copying machine, and in this figure, reference numeral 1 denotes a photosensitive drum. The photosensitive drum 1 performs charging, exposure, development, and transfer while rotating in the direction of arrow X. A developing section 2 is provided near the photosensitive drum 1. The developing section 2 includes a magnetic roller 5 that adsorbs a developer 4 made of a mixture of a magnetic carrier and toner and applies the toner to the photosensitive drum 1 in a case body 3, and a magnetic roller 5 that attaches the developer 4 to the magnetic roller 5. The structure includes a regulating member 6 that regulates the amount of developer that is adsorbed, and an agitation roller 7 that agitates the developer 4 in the case body 3.

The magnetic roller 5 is disposed close to the photosensitive drum 1, and is provided with a sleeve 5a on its circumferential surface that rotates in the direction of arrow Y. A potential having a polarity different from the charging polarity of the toner in the developer 4 is supplied to the sleeve 5a. Further, the magnetic roller 5 is magnetized at predetermined locations as follows. That is, the N ₁ and N ₂ poles are formed at a location close to the photosensitive drum 1 and at a location almost opposite thereto, and the N ₁ and N ₂ poles are formed below between these N 1 and N ₂ poles. The S ₁ pole is formed at a location forming a predetermined angle (θ degree, approximately 1/3 of the angle between the N ₁ and N ₂ poles), and the N ₁ ,
N On the upper side between _{the two} poles, there is a
S ₂ poles are formed. In this case, the above S ₁ pole and
The intermediate location between the N ₂ pole, that is, the location θ degrees away from the S ₁ pole toward the N ₂ pole, is where the developer adsorbed to the sleeve 5a is located.
The magnetic force is so weak (approximately 100G to 500G) that it is almost shaken off by the centrifugal force. Therefore, the magnetic roller 5, due to its magnetic force, pushes the sleeve 5a
The developer 4 is adsorbed onto the magnetic brush 5 in the form of a brush.
b, and this magnetic brush 5b constitutes the sleeve 5a.
As the sleeve 5a rotates, it comes into sliding contact with the surface of the photosensitive drum 1 and applies toner to the surface of the photosensitive drum 1, and the developer 4 adsorbed onto the sleeve 5a is moved by the centrifugal force caused by the rotation of the sleeve 5a. ₁ pole and
It is designed to be shaken off at a point approximately in the middle of the _N2 pole (that is, at a point θ degrees away from the _S1 pole).

Further, the regulating member 6 is configured to reduce the N ₂ of the magnetic roller 5.
A doctor part 6a is arranged approximately between the pole and the _S2 pole, and regulates the adsorption amount of the developer 4 on the sleeve 5a of the magnetic roller 5 to a constant amount. and a guide plate 6b that sends excess developer 4 to the lower part of the case body 3.

Further, the stirring roller 7 is arranged at the lower part of the case body 3 and at a location approximately halfway between the N ₂ pole and the S ₁ pole of the magnetic roller 5, that is, at a location away from the S ₁ pole by θ degrees toward the N ₂ pole side. Moreover, this stirring roller 7 is configured to rotate in the direction of arrow Z. That is,
A rotating shaft 8 is arranged parallel to the magnetic roller 5, and a large number of blades 9 are attached to this rotating shaft 8. As shown in FIG. 2, the blade 9 is connected to the developer 4
An elliptical disc 9a that stirs the water in the axial direction is attached to the rotating shaft 8.
bosses 9b, 9b are formed in the center of this disc 9a along the rotation axis 8, and fins 9c, which stir the developer 4 in the rotational direction, are attached to the bosses 9b, 9b in the rotational direction. 9c. In this case, the fins 9c, 9c
The tip of the magnetic roller 5 in the circumferential direction rotates very close to the surface of the magnetic roller 5. The blade 9 is made of a non-magnetic material, for example, if the toner is used for development with negative polarity, it may be made of a material that has a higher triboelectrification series than the toner material, or if the toner is used for development with positive polarity. If this is the case, a material with a triboelectrification level lower than that of the toner material is used, and it is preferable to use a material integrally molded with plastic.

Next, the operation of the developing section 2 of the electronic copying machine configured as described above will be explained. First, the developer 4 is attracted onto the sleeve 5a near the _N2 pole by the magnetic force of the magnetic roller 5. This adsorbed developer 4 is
As the sleeve 5a rotates, it moves in the direction of arrow Y, and is regulated to a constant amount by the doctor section 6a of the regulating member 6. In this case, the regulated excess developer 4 is guided to the lower part of the case body 3 by the guide member 6b. The developer 4 on the sleeve 5a regulated by the regulating member 6 moves in the direction of the arrow Y as a magnetic brush 5b and rubs against the surface of the photosensitive drum 1, thereby removing the toner in the developer 4 from the photosensitive drum. Apply to the surface of 1. After this, the magnetic brush 5b is attached to the sleeve 5.
It further moves in the direction of the arrow Y with the rotation of a, and after passing the S ₁ pole of the magnetic roller 5, the developer 4 on the sleeve 5a is gradually shaken off by the centrifugal force caused by the rotation of the sleeve 5a, and moves away from the S ₁ pole by θ degrees. The developer is almost 4
shake it off. In this case, since the fins 9c, 9c of the stirring roller 7 come very close to the surface of the magnetic roller 5 and rotate in the direction of arrow Z, the developer 4 that has not been shaken off is almost completely absorbed by the magnetic roller 5 by the fins 9c, 9c. scraped off from the surface of 5. The developer 4 thus scraped off and the developer 4 shaken off are stirred by the stirring roller 7. That is, as the rotating shaft 8 rotates, the blades 9 rotate in the direction of arrow Z, and as a result, the elliptical disk 9a of the blade 9 rotates irregularly in an obliquely inclined state, thereby stirring the developer 4 in the axial direction. At the same time, each fin 9c, 9c of the blade 9
rotates to agitate the developer 4 in the rotational direction. As a result, the developer 4 within the case body 3 is uniformly dispersed. The developer 4 thus dispersed is again adsorbed onto the sleeve 5a by the magnetic roller 5 as described above, and the above-described operation is repeated.

In this way, according to the developer stirring device, a large number of blades 9 are attached to the rotating shaft 8, and the blades 9 are connected to an elliptical disc 9a that is obliquely inclined with respect to the rotating shaft 8, and a magnetic roller 5. Since the fins 9c, 9c rotate very close to each other, the developer 4 can be stirred in the axial direction by the elliptical disk 9a, and the developer 4 can be stirred in the rotational direction by the fins 9c, 9c. As a result, the developer 4 can be uniformly dispersed within the case body 3, and the developer 4 can be uniformly adsorbed onto the sleeve 5a, so that the toner can be properly applied to the photosensitive drum 1. can. In addition, each fin 9c, 9 of the blade 9...
c... rotates very close to the magnetic roller 5, the developer 4 that has not been shaken off from the surface of the sleeve 5a can be scraped off by the fins 9c, 9c... Since there is no need to provide any drop plate or the like, the structure is not only simplified, but also the case body 3 can be manufactured compactly and at low cost.

In the above embodiment, the case where the stirring roller 7 was provided in the developing section 2 of the electronic copying machine was explained.
This invention is not limited to this, and can be applied to, for example, a cleaning section of an electronic copying machine.

As explained above, according to the developer stirring device of this invention, the developer adhering to the surface of the magnetic roller is scraped off, and the stirring roller for stirring the scraped off developer is placed close to the magnetic roller. Because of this arrangement, the developer can be effectively scraped off from the surface of the magnetic roller without using any scraping plate or the like, and the scraped developer can be stirred so as to be uniformly dispersed. There is an advantage. In addition, by using a material that easily imparts the polar charge that the toner should retain during development through frictional charging as the material constituting the stirring roller, the development characteristics of the stirred toner are improved, resulting in clearer images. There is also the advantage that it is possible to form images.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing the developing section of the electronic copying machine according to this invention, Fig. 2 shows its stirring roller, Fig. 2 A is a partially omitted front view, and Fig. 2 B shows its main parts. FIG. 4... Developer, 5... Magnetic roller, 7... Stirring roller.

Claims (1)

[Scope of utility model registration request] A rotating sleeve has a plurality of fixed magnetized parts disposed therein, and a magnetic roller that magnetically attracts toner to the surface of the sleeve and conveys the toner, and a rotating rotating sleeve that is pivoted at a position opposite to a non-magnetized part of the magnetic roller. a stirring roller having a fin whose tip approaches the sleeve surface to scrape off the toner and a disk that moves the toner scraped off by the fin in the axial direction; A magnetic brush device characterized in that the roller is made of a material that charges the toner with a polar charge that is to be retained during development by stirring and rubbing the toner.