JPS61166569A - Developing device - Google Patents

Abstract

PURPOSE:To facilitate controlling supply and stop of a developer by constituting a part of magnetic pole parts of the first and the second developing bodies with an electromagnet at least. CONSTITUTION:The fourth magnetic pole part 34b consists of the electromagnet and is controlled by a control part 35a so that power is supplied to it at the development time and power supply to it is stopped at the development stop time. The fifth magnetic pole part 45f consists of the electromagnet and is controlled by a control part 35b so that power is supplied to it at the development time and power supply to it is stopped at the development stop time. When development of an electrostatic latent image is completed, power supply to the fourth magnetic pole part (electromagnet) 34b of the first developing roll 20 is stopped, and a developer magnetic brush Da' is not formed to stop supply of a developer Da. Then, power supply to the fifth magnetic pole part (electromagnet) 45f of the second developing roll 21 is stopped, and the developer magnetic brush Da' is not formed, and supply of a developer Db is 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 that integrate a developing device and a photoreceptor have been prepared and selectively replaced, which has caused the problem that the operation is extremely troublesome. .

Therefore, by selectively driving the first developing body and the second developing body by switching operation of the oiler, etc., a two-color color development system is developed in which the electrostatic image on the photoreceptor can be developed. Development of the device is currently underway by the present inventors.

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

During development, the rotating sleeve is rotated, and a developer brush held on the surface of the rotating sleeve comes into sliding contact with the photoreceptor to develop the electrostatic latent image.

Then, when the development is completed, the supply of developer is stopped.

However, conventionally, when stopping the supply of developer, the rotary sleeve is rotated in the opposite direction to that during development, and the developer on the rotary sleeve is scraped off by a scraping means, and the supply of developer is stopped. Measures were taken to stop it. For this reason, there are disadvantages in that the structure becomes complicated and control becomes troublesome.

[Purpose of the invention]

The present invention has been made in view of the above report, and an object thereof is to provide a developing device that can stop the supply of developer with a simple configuration.

[Summary of the invention]

In order to achieve the above object, the present invention eliminates the need for operations such as rotating the rotating sleeve in reverse by configuring at least some of the plurality of magnetic pole parts of the first and second developing bodies with electromagnets. This allows the supply of developer to be stopped.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to an embodiment shown in the drawings. FIG. 1 shows the configuration of the main parts of a color copying machine incorporating the developing device of the present invention, and in the figure, 1 is a drum-shaped photoreceptor as an image carrier provided approximately at the center of the main body of the copying machine. This photoreceptor I has a drum diameter of 78 mm and is surrounded by a charging device 2, an exposure device 3, a two-color developing device 4 (described later), a transfer device 5, a peeling device 6, a cleaning device 7, and an afterimage. Erasing devices 8 are sequentially arranged.

Further, in the lower part of the copying machine main body, paper P1 automatically taken out from a paper feed cassette (not shown) and manually fed paper P are transferred through an image transfer section 9 between the photoreceptor 1 and the transfer device 5. A paper transport path lO leading to a paper discharge tray (not shown) is formed.

A pair of aligning rollers 11 are arranged on the upstream side of the image transfer section 9 of the paper transport path 10, and a fixing device and a pair of paper ejection rollers (not shown) are arranged on the downstream side.

Further, the photoreceptor I is connected to a drive mechanism (not shown):
It is driven in the direction of the arrow (clockwise in the state of FIG. 1) in synchronization with a document table (not shown). First, the charging device 2 charges the document uniformly, and the exposure device 3 forms an image of the document set on the document table υ on the photoreceptor l, forming an electrostatic latent image. . Next, the electrostatic latent image on the photoreceptor 1 is sent by the developing device 4 to the transfer device 5 as a developing image.

A sheet P fed automatically or manually is fed by a pair of aligning rollers 1, and a developer image previously formed on a photoreceptor I is transferred to the sheet PK by a transfer device 5. moreover,
The peeling device 6 using AC corona discharge is peeled off from the photoconductor L, passes through the conveyance path 10, and is transferred to the fixing device.The developed side image is melted and fixed on the paper P, and the paper is ejected by the paper ejection roller pair. It is ejected onto the tray.

On the other hand, after the developer image is transferred onto the paper P, residual toner remaining on the photoconductor 1 is cleaned by a cleaning device 7, and an afterimage erasing device 8 partially levels the potential on the photoconductor 1. Drop it to the following to make it ready for the next copy operation.

The developing device 4 includes a developing roller 2 as a first developing body.
0. It also has a developing roller 2I as a second developing member, and these developing rollers 220.degree. 21 are selectively driven so that, for example, black or red color can be developed.

Further, the developing device 4 includes a first developing unit 22 including a first developing roller 20, and a second developing unit 22 including a second developing roller 2I.
The first developing unit 22 in the upper stage uses a red developer Da, which is rarely used, and the second developing unit 23 in the lower stage uses a black developer Db, which is frequently used. is now used.

Note that the developers Da and Db are two-component developers consisting of toner and carrier.

Further, as shown in FIGS. 2 and 3, the first developing unit 22 that uses the red developer Da has a developing mechanism section 2.
4 and a developer agitating section 25, a first developing roller 20 as a first developing body, and a photoreceptor l of a developer magnetic brush Da' formed on the surface of the first developing roller 20. That is, a sliding contact portion 27 is provided on the upstream side of the developing position 26 and regulates the thickness of the developer magnetic brush Da', and a surface of the developing roller 2Q is provided on the downstream side of the developing position 26. A casing 31 houses a scraper 29 that scrapes off a certain developer magnetic brush Da' and guides it to the developer storage section 28, and a developer stirring body 30, 30 accommodated in the developer storage section 28. .

Further, the first developing roller 2Q includes a magnetic roll 32,
It consists of a rotating sleeve 33 that is fitted onto the magnetic roll 32 and rotates clockwise in the figure.

Moreover, the magnetic roll 32 has five magnetic pole parts 34a to 34e. Third. Fifth magnetic pole portions 34th, 34e
, 34e are N poles, the second . Fourth magnetic pole portions 34b, 34d
is the S pole, and each magnetic pole part 34a to 34e is about 50
The third one is placed at an angle of 70° and opposite the development position.
The magnetic pole part 34c is 700-10007! ? the other magnetic pole part 34a.

34b, 34d, and 34e have a magnetic force distribution of 3oO to 600 Gauss.

The fourth magnetic pole section 34b is constituted by an electromagnet, and is controlled by the control section 35m so that it is energized during development and de-energized when development is stopped. ing.

Therefore, in the first developing unit 22, the rotary sleeve 33 is rotated clockwise in the figure to develop the image, which is the so-called advanced mode. The electrostatic latent image formed on the photoreceptor 1 is developed by sliding a developer brush Da' held on the surface thereof in the direction of the photoreceptor 1.

Further, as shown in FIGS. 4 and 5, the second developing unit 23 that uses the black developer Db has a developing mechanism section 3.
6 and the developer agitating section 37, a second developing row 221 as a second developing body, a developing roller 1.11 formed on the surface of this developing roller 2I, a photoreceptor I of the image side magnetic brush Db', sliding contact area
:.

That is, there is a doctor 39 which is provided upstream of the development position 38 and regulates the thickness of the developer magnetic brush Db', and the developer Db scraped off by this doctor 39 is transferred to the developer storage section 40.
A casing 43 houses the developer agitating body 42 accommodated in the developer accommodating portion 40 and the developer accommodating portion 40 .

The developing roller 21 is composed of a magnetic roll 44 and a rotating sleeve 45 that is fitted around the magnetic roll 44VC and rotates counterclockwise in the figure.

In the second developing unit 23, the developing roller 23 is made larger than the first developing roller 20 in order to enable high-speed development, and the rotating sleeve 45 is rotated counterclockwise in the figure to perform development. In the so-called with mode, by sliding the developer brush Da' held on the surface of the photoconductor in a direction that follows the flow of the image on the photoconductor, sufficient development time is secured, and the photoconductor The electrostatic latent image formed on the image is developed into a high-quality image.

The magnetic roll 44 has six magnetic pole parts 45a to 45f, which is one more than the first developing row 220, so as to be suitable for the with mode. 4th. Sixth magnetic pole part 4
5b, 45d, 45f are N poles, the 11th 3rd... Fifth magnetic pole portion 45h+45c.

45 is an S pole, each magnetic pole part 45h to 45f is arranged at an angle of about 50° to 60°, and the fourth magnetic pole part 45d facing the development position is 800 to 1001/us, and the other magnetic poles are arranged at an angle of about 50° to 60°. Part 45 ' * ' 5 b 145c T45・
, 45f has a magnetic force distribution of 400 to 600 fus.

The fifth magnetic pole section 45f is constituted by an electromagnet, and is controlled by the control section 35b so that it is energized during development and de-energized when development is stopped. There is.

When the first developing unit 22 side is designated to be operated, the rotating sleeve 33 of the first developing roller 20 rotates clockwise, and the fourth magnet (electromagnet) 34b is energized to generate a magnetic force. As a result, a developer magnetic brush Da' is formed on the surface of the rotating sleeve 33. Then, the electrostatic latent image formed in advance on the photoreceptor L is transferred to a red developer P.
It will be developed with a /.

When the development of this electrostatic latent image is completed, the power supply to the fourth magnet (electromagnet) 34b of the first developing roller 20 is stopped, and the developer magnetic brush Da' is not formed and the developer Da
supply will be stopped.

Further, when the second developing unit 23 side is designated to be operated, the rotating sleeve 45 of the second developing row 22I
rotates counterclockwise and the fifth magnet (electromagnet)
45f is energized, a magnetic force is generated, and a developer magnetic brush Da' is formed on the surface of the rotating sleeve 450. And, in order to cope with high-speed copying, the photoreceptor is rotated at a high speed during development by the first developing unit 22! The electrostatic latent image previously formed thereon is developed with black developer Db.

When the development of this electrostatic latent image is completed, the energization to the fifth magnet (electromagnet) 45f of the second developing roller 21 is stopped, and the developer magnetic brush Da' is not formed, and the developer D
The supply of b is stopped.

At this time, the rotating sleeve 33 of the first developing unit 22 is also not provided with the developer magnetic brush Da/, and even if any of the developing units 22 and 23 is designated next, the rate of color mixing etc. will be affected. is designed to prevent this from occurring.

In addition, the first developing unit 22 in the upper stage is used for red color development.
Although the second developing unit 23 at the lower stage has been described for developing black color, it is not limited thereto and may be for other colors.

In addition, it goes without saying that the present invention can be modified in various ways without departing from the gist of the invention.

〔Effect of the invention〕

As explained above, in the present invention, since at least a portion of the magnetic pole parts of the first and second developing bodies are constituted by electromagnets, the first and second developing bodies can be moved by simply turning on and off the electricity to the electromagnets. This has the advantage of being able to control the supply and stop of developer during busy periods, simplifying the structure, and facilitating control.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a schematic configuration diagram showing the main parts of a copying machine, FIG. 2 is a sectional view showing a first developing device, and FIG. FIG. 3 is a cross-sectional view showing a developing device. DESCRIPTION OF SYMBOLS 1... Image carrier (photoreceptor), 20... First developing body (first developing roller), 2I... Second developing body (second developing body)
developing roller), 34a to 346... magnetic pole portion, 45n
~45f...Magnetic pole part. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (1)

[Claims] A first and a second developing body are disposed adjacent to each other facing the image bearing member, and each of the first and second developing bodies has a plurality of rollers for conveying and supplying developer to the image bearing member. What is claimed is: 1. A developing device having magnetic pole portions, wherein at least a portion of the magnetic pole portions of the first and second developing bodies are constituted by electromagnets.