JPS61170762A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a color mixture of a developer by providing a diamagnetic material so as to be freely movable on the first and the second developing bodies, respectively, and positioning the diamagnetic material between plural magnetic pole parts, when stopping development. CONSTITUTION:Brass 10 functioning as a diamagnetic material is attached so as to be freely turnable to a revolving shaft 7a of a magnetic roll 7. When ending development by the first developing device 3, the diamagnetic material 10 provided on the magnetic roll 7 is positioned between the first magnetic pole part 9a and the fifth magnetic pole part 9e, and when ending development by the second developing device 4, a diamagnetic material 17 provided on a magnetic roll 15 is positioned between the third magnetic pole part 16c and the fourth magnetic part 16d. In this way, a magnetic field formed between the first and the fifth magnetic pole parts 9a, 9e, and between the third and the fourth magnetic pole parts 16d, 16d is cut and a developer magnetic brush annihilates, and it can be prevented exactly that unnecessary developers 23, 24 adhere to a photosensitive drum 1 from developing rollers 6, 14 of the developing devices 3, 4 being in a state that the development has been stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developing device that can be applied to, for example, a two-color color copying machine.

[Technical background of the invention and its problems]

Conventionally, in this type of two-color color copying machine, a plurality of cartridges, each of which has an integrated copying device and a photoreceptor, have been prepared and selectively replaced, which has had the problem of being extremely troublesome to operate. there were.

Therefore, it is preferable to selectively drive the first developing body and the second developing body by an operator's button switching operation, etc., to develop a two-color color developing system that can develop an electrostatic image on a photoreceptor. Development of the device is underway by the present inventors.

The first and second developing bodies used include, for example, a magnetic roll having a plurality of magnetic pole parts and a rotating sleeve that is fitted around the magnetic roll and rotates.

The first and second developing bodies generate a developer magnetic brush by the magnetic force formed between the magnetic poles of the magnetic rolls, and develop the electrostatic latent image by sliding it into contact with the electrostatic latent image on the photoreceptor. It looks like this.

However, in the past, due to the influence of the magnetic force between the magnetic poles of the magnetic roll, for example, even if the drive of the first developer is stopped, developer remains on the rotating sleeper, and this is transferred to the second developer. There was an inconvenience that it adhered to the photoreceptor and mixed colors when the body was driven.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a developing device that has a simple configuration and is capable of preventing color mixing of developers.

[Summary of the invention]

In order to achieve the above object, the present invention provides a movable diamagnetic material in each of the first and second developing bodies, and when development is stopped, the diamagnetic material is positioned between a plurality of magnetic pole parts. It is designed to eliminate the developer magnetic brush by blocking the magnetic force generated by the developer.

[Embodiments of the invention]

Hereinafter, the present invention will be described with reference to an embodiment shown in the drawings. In the figure, reference numeral 1 denotes a photosensitive drum as an image carrier, and a developing device 2 is provided adjacent to the photosensitive drum 1. The developing device 2 has first and second developing devices located above and below.
The developing device 3.4 is composed of a developing device 3.4. The first developing device 3 includes a first developing roller 6 serving as a first developing body within a casing 5 thereof. The first developing roller 6 is constituted by a magnetic roll 7 and a rotating sleeve 8 that rotates with the magnetic roll 7 fitted onto the outside. The magnetic roll 7 includes first to fifth magnetic pole parts 9&~9. The first, third, and fourth magnetic pole parts 9*, 9c, and 9d are N poles,
The second and fourth magnetic pole portions 9b and 9* are S poles.Furthermore, a brass 10 as a diamagnetic material is rotatably attached to the rotating shaft 7m of the magnetic roll 7. This brass 1
As shown in FIGS. 2 and 3, a lever 11 is connected to one end of the lever 1), a solenoid 12 is connected to one end of the lever 1), and a spring 13 is connected to the other end. There is. The brass 10 is a solenoid 12.
It is turned on and off.

When it is on (during development), it faces the fifth magnetic pole part 9e as shown by the broken line in FIG. The trap is positioned between the magnetic pole part 9 and the magnetic pole part 9. Above brass (diamagnetic material) 1
0 is the S pole of the magnet 11 and the ON of the magnet 12 as shown in FIG.
When placed between the magnets 11 and 12, it has the property of reducing the magnetic field formed between the magnets 11 and 12.

- 10,000, the second developing device 4 is provided with a second developing roller 14 as a second developing body within its casing 41. This second developing roller 14 is also constituted by a magnetic roll 15 and a rotating sleeve 16 which fits around this magnetic roll 15 and rotates. The magnetic roll 15 has first to sixth magnetic pole parts 161 to 161, and the first, third, and fifth magnetic pole parts 16m, 16e, and 16m are S poles, and the second, fourth, and sixth magnetic pole parts are S poles. Sections 16b, 16d.

161 is the north pole. Further, the magnetic roll 15
A brass 17 as a diamagnetic material is rotatably attached to the 0-rotation shaft 15h in the same manner as shown in FIGS. 2 and 3. A lever 18 is connected to one end of this brass 17, and a solenoid 19 is connected to one end of this lever 18.
A sedge ring 20 is connected to the other end.

The brass 17 turns on the solenoid 19.

When it is turned off, it is rotated once, and when it is turned on (during development), it faces the fourth magnetic pole part 16d, as shown in FIG. 1, and when it is turned off (when development is stopped), it faces the third magnetic pole part 16e. Fourth magnetic pole part 1g&
It is now located between. When the brass (diamagnetic material) 17 is located between the S pole of the magnet B and the N pole of the magnet B as shown in FIG. are doing.

Note that 21 and 22 in Figure 1 are the first and second developing units 3.
, 4 is an agitation conveyance mechanism provided in the casing 5.13 of the casing 5.
, 13 so that the developer: 23.24 is agitated and conveyed to the first and second developing rolls 6°14.

Further, the developer 2 in the casing 5 of the first developing device 3
The developer 24 in the casing 13 of the second developing device 4 is black and consists of toner and carrier.
1 Also, the rotation speed IJ of the first developing roller 6
- The sleeve 8 is rotated clockwise by a drive mechanism (not shown), and the rotary sleeve 16 of the second developing roller 14 is rotated counterclockwise.

For example, when making a red copy using the first developing device 3, the solenoid 12 is turned on and the lever I is rotated against the biasing force of the spring 13.
The diamagnetic material (brass) 10 is the fifth magnetic pole part 9 of the magnetic roll 7
The first magnetic pole part (main pole) 9m and the fifth magnetic pole part (
A magnetic field is generated between the transport pole 9e and a developer magnetic brush. From this state, the first developing roller 6
The rotating sleeve 8 is rotated clockwise, and the developer magnetic brush comes into sliding contact with the electrostatic latent image formed on the photosensitive drum 1, thereby copying the image in red.

When the red color development by the first developing device 3 is completed, the rotation of the rotating sleeve 8 is stopped, the solenoid 12 is turned off, and the developer 11 is rotated by the biasing force of the spring 13. ) is rotated clockwise and positioned between the first magnetic pole part 9a and the fifth magnetic pole part 9e. As a result, the magnetic force generated between the first magnetic pole part 9a and the fifth magnetic pole part 98 is cut off.

The developer magnetic brush disappears and the supply of developer 23 is stopped.

On the other hand, when making a black copy using the second developing device 4, the solenoid 19 is turned on and the lever 18 is rotated against the biasing force of the spring 13.
7 faces the fourth magnetic pole part 16d of the magnetic roll 15, and the third
magnetic pole part (main pole) 16C and fourth magnetic pole part (carrying pole) 16
A magnetic field is generated between the developer and the developer magnetic brush. From this state, the rotating sleeve 16 of the developing roller 14 is rotated clockwise, and the developer magnetic brush comes into sliding contact with the electrostatic latent image formed on the photosensitive drum 1, thereby copying it in black. .

When the black color development by the second developing unit 4 is completed, the rotation of the rotating sleeve 160 is stopped, the solenoid 19 is turned off, and the sillper 18 is rotated by the biasing force of the spring 20, and the diamagnetic material (brass) is rotated. 17 is rotated clockwise to form the third magnetic pole part 16a and the fourth magnetic pole part 16.
It is located between d. Accordingly, the third magnetic pole portion 16c
The magnetic field generated between and the fourth magnetic pole portion 16d is cut,
The developer magnetic brush disappears and the supply of developer is stopped.

As described above, according to this embodiment, the first developing device 3
When the development by the second developer 4 is completed, the diamagnetic material (brass) 10 provided on the magnetic roll 7 is placed between the first magnetic pole part 9a and the fifth magnetic pole part 9e, and when the development by the second developer 4 is completed, the diamagnetic material (brass) 10 provided on the magnetic roll 7 is placed between the magnetic roll 15. The provided diamagnetic material (brass) 17 is connected to the third magnetic pole part 16
c and the fourth magnetic pole part 16d.
The magnetic field formed between the fifth magnetic pole portions 9m and 9e and between the third and fourth magnetic pole portions 16c and 16d is applied so that the developer magnetic brush disappears, and the developer 3 is in a state where development is stopped. Alternatively, it is possible to reliably prevent unnecessary developer 23 or 24 from adhering to photosensitive drum 1 from developing roller 6 or 14 of 4.

Note that the present invention is not limited to the above embodiment,
Of course, various modifications can be made within the scope of the gist.

〔Effect of the invention〕

As explained above, in the present invention, a diamagnetic material is movably provided in each of the first and second developing bodies, and when development is stopped, the diamagnetic material is positioned between a plurality of magnetic pole parts. Since it blocks the generated magnetic force, there is no risk of unnecessary developer adhering to the image bearing member, and it has the effect of preventing color mixing and making it possible to obtain high-quality multicolor images.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a schematic configuration diagram showing a developing device, FIG. 2 is a perspective view showing its internal structure and drive mechanism, and FIG. 3 is a longitudinal sectional view thereof; FIG. 4 is an explanatory diagram showing the characteristics of diamagnetic material. DESCRIPTION OF SYMBOLS 1... Image bearing member (photosensitive drum), 6... First developing body (first developing roller), 14... Second developing body (second developing roller), 91-9e. ...Magnetic pole part, 161~
J6f...Magnetic pole part, 10.17...Diamagnetic material (brass). Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (2)

[Claims] (1) First and second developing bodies are disposed adjacent to each other facing the image carrier, and the first and second developing bodies are arranged in a plurality of blocks for conveying and supplying developer to the image carrier. In the device having magnetic pole portions, an antireflector is movably provided on each of the first and second developing bodies and moves between the plurality of magnetic pole portions when development is stopped to block the magnetic force formed between the magnetic pole portions. A developing device characterized by being equipped with a magnetic material. (2) The developing device according to claim 1, wherein the diamagnetic material is brass.