JPS6255681A - Magnetic brush developing device - Google Patents

Abstract

PURPOSE:To reduce the rotational load torque of a rotary sleeve, and to equalize the height of a magnetic brush of a developer by providing a developer control member for controlling the developer in a part where the magnetic flux density is low, and a movable developer forming member for pressing the developer by a prescribed force and making it even at this side of an electrostatic latent image development use magnetic pole. CONSTITUTION:If a developer tuft tip forming blade 31 is pressed against a sleeve 1 too strongly, or the blade 31 is fixed, a leveling action of the blade 31 becomes a scraping action, and a developer 7 collects little by little between the developer tuft tip forming blade 31 and a developer tuft tip controlling blade 8. As a result of its action, a rotational load torque of the sleeve 1 increases, but the pressing force of the developer tuft tip forming blade 31 is selected to a moderate pressing force which exceeds a force required for leveling the developer but does not scrape it down, and also a structure of the device is freely rotatable, therefore, a magnetic brush 13 which is uniform in the width direction is formed without increasing a load torque of the sleeve 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic brush developing device used in a printer employing a dry electrophotographic method.

[Conventional technology]

Figures 2 and 3 show a conventional magnetic brush developing device as shown in, for example, Japanese Patent Publication No. 59-29870. In Figure 2, 1 is a cylindrical rotatable sleeve made of non-magnetic material. There is a main pole 2 made of a fixed permanent magnet inside.
A sub-pole 3.4.5 is arranged. Opposed to the main pole 2, a drum-shaped electrostatic latent image support 6 is rotating in the direction of the arrow. 7 is a two-component dry developer that is a mixture of a carrier made of iron powder and a toner made of carbon and resin powder; 8 is a blade for regulating the tip of the developer; The sub-pole 3 is attached to the housing 9 on an extension of a line connecting approximately the middle of the sub-pole 3 with its tip spaced from the outer peripheral surface of the sleeve 1 by about 4 mm.

10 is a scraper whose one end is attached to the sleeve 1 with a slight gap; 11 is an impeller mounted rotatably;
12 is a toner tank containing toner, and 13 is a magnetic brush for developer formed on the main pole 2.

In addition, in FIG. 3, the same reference numerals as in FIG. 2 indicate the same parts, and 31 is a triangular prism-shaped nonmagnetic body that faces the sub-poles 3a and 3b and whose tip is attached with a distance of about 5 mm from the sleeve 1. This is a developer regulating member consisting of:

Next, the operation will be explained. In FIG. 2, as the impeller 11 rotates, the toner replenished from the toner tank 12 is transferred to the developer 7 that has accumulated at the bottom of the housing 9.
and stirred. The developer is transported from the sub-pole 5°3 to the main pole 2 as the sleeve 1 rotates in the direction of arrow F.
On the way, more than a certain amount of the developer is scraped off by the developer tip regulating blade 8, and a magnetic brush 13 with tips of the same height is formed at the position of the main pole 2. The tip of the toner comes into contact with the electrostatic latent image support 6, and the toner in the developer 7 adheres to the electrostatic latent image support 6, thereby performing development. The developer 7 that has completed development is conveyed to the sub-pole 4 as the sleeve 1 rotates, is scraped off from the sleeve 1 by a scraper 10, and falls onto an impeller 11.

Also, in Fig. 3, the operation is the same as in the second time, but
In Fig. 2, the developer tip regulating blade 8 is installed between the sub-pole 3 and the main pole 2, which have a considerably high magnetic flux density, but in Fig. 3, the blade 8 for regulating the developer tip is installed near the sub-pole 3b, where the magnetic flux density is relatively low. What is different is that they are arranged in different ways.

[Problem that the invention seeks to solve]

Since the conventional magnetic brush developing device is constructed as described above, in the magnetic brush developing device shown in FIG. Since the developer is conveyed while aligning the height of the tips, the frictional force between the developer, the developer tip regulating blade 8, and the sleeve 1 increases, and the rotational load torque of the sleeve 1 becomes large. A large torque motor was required as the drive motor. In addition, in FIG. 3, in order to solve the above-mentioned problem in FIG.
Although the blade 31 for regulating the developer tip is placed near b.
The transport distance from to the main pole 2 is long, and there is a sub-pole 3a on the way.
Because of this, the magnetic flux density in the axial direction is uneven (especially high at both ends).
Although the developer moves in the axial direction during conveyance due to the tendency to This causes problems such as uneven development and background smearing.

This invention was made to solve the above-mentioned problems, and it is possible to reduce the rotational load torque of the sleeve, reduce the size and weight of the sleeve drive motor, and
It is an object of the present invention to provide a magnetic brush developing device capable of making high-quality development by making the height of the magnetic brush uniform.

[Means for solving problems]

The magnetic brush developing device according to the present invention includes a developer regulating member that regulates the developer at a position facing the developer conveying magnetic pole having a relatively low magnetic flux density, and a developer regulating member that regulates the developer. A movable developer forming member is disposed at a position opposite to the intermediate position of the conveying magnetic pole to press and level the developer with a predetermined pressing force.

[Effect]

In this invention, there is a developer regulating member that regulates the developer in an area with low magnetic flux density, and a movable developer molding that presses the developer with a constant force and smoothes it in front of the electrostatic latent image developing magnetic pole. Since the member is provided, it is possible to reduce the rotational load torque of the rotating sleeve and to make the height of the magnetic brush of the developer uniform.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a sectional view of a magnetic brush developing device according to an embodiment of the present invention. Rotationally driven in direction A. Inside this sleeve 1 is a main pole (magnetic pole for electrostatic latent image development) made of a fixed permanent magnet.
Subpole (magnetic pole for developer transport) 3.4. j is arranged. The main pole 2 is arranged to face the side surface of the electrostatic latent image support 6, and has a strength such that the magnetic flux density on the surface of the sleeve 1 is about 800 Gauss. 7 is a two-component dry developer, and the sub-electrode 3. 4. Reference numeral 5 denotes a magnetic pole for conveying and discharging the developer 7, and a magnetic pole whose magnetic flux density on the surface of the sleeve 1 is slightly weaker than that of the main pole 2 is used. 8
A developer tip regulating blade (developer regulating member) is fixed to the housing 9 with its tip facing the sub-pole 5 at a distance of about 3 mm from the outer peripheral surface of the sleeve 1. 1
0 is a scraper whose one end is attached to the sleeve 1 with a small gap, 11 is an impeller mounted rotatably,
It is rotationally driven by the same rotational drive source as the sleeve 1. 1
2 is a toner tank containing toner; 13 is a magnetic brush for developer 7 formed on main pole 2; Reference numeral 31 denotes a developer tip forming blade (developer forming member), one end of which is disposed at a position facing approximately midway between the main pole 2 and the sub-pole 3, and the other end is rotatable on the support block 32. It is attached to the sleeve 1 and is shaped so that the load toward the center of the sleeve at the tip facing the sleeve 1 is approximately 400 g.

Next, the operation will be explained.

The toner supplied from the toner tank 12 is agitated with the developer 7 accumulated at the bottom of the housing 9 by two impellers 11 . As the sleeve 1 rotates in the direction of arrow A, the developer is transported from the sub-pole 5 to the sub-pole 3 and then to the main pole 2. of developer will be transported.

While the developer 7 on the sleeve 1 is conveyed to the main pole 2 via the sub-pole 3, some of the developer moves slightly in the width direction due to variations in the magnetic flux density in the width direction of the sub-pole 3. 2, the developer 7 is non-uniform in the width direction. The uneven developer is leveled in the width direction by a developer tip shaping blade 31, and a magnetic brush 13 having a uniform height over the entire width is formed on the main pole 2. If the pressure of the developer tip shaping blade 31 on the sleeve 1 is too strong or if the blade 31 is fixed, the leveling action of the blade 31 becomes a scraping effect, and the developer 7 is removed from the developer tip shaping blade 31. The rotational load torque of the sleeve 1 increases accordingly, but the pressing force of the developer tip shaping blade 31 is reduced to the force necessary to level the developer 7. Since an appropriate pressing force is selected that does not cause scraping on the plate, and the structure is rotatable, a uniform magnetic brush 13 can be formed in the width direction without increasing the load torque of the sleeve 1. The developer 7 that has completed development is conveyed to the sub-pole 4 as the sleeve 1 rotates, is scraped off from the sleeve 1 by the scraper 10, and is moved to the impeller 11.
fall on top.

In this way, in this embodiment, the conveyance amount of the developer is regulated at the position opposite to the sub-pole, which has a relatively weak magnetic force, and the surface of the developer is pressed at a predetermined position at the position opposite to the position in front of the main pole. Since it is leveled by pressure, it is possible to reduce the load torque on the sleeve and form a magnetic brush with a uniform height in the width direction.

In the above embodiment, a structure is shown in which the pressing force of the developer tip forming blade 31 against the sleeve is obtained by the weight of the blade 31, but this also applies if a predetermined pressing force is obtained by a spring. good.

〔Effect of the invention〕

As described above, according to the magnetic brush developing device of the present invention, the developer spike regulating member is disposed at a position facing the developer transporting magnetic pole, and the electrostatic latent image developing magnetic pole and the transporting magnetic pole are arranged opposite to each other. Since the structure is such that a rotatable developer spike forming member is disposed at a position opposite to the intermediate position to press and level the developer with a predetermined pressing force, the torque required to rotate the rotating sleeve is reduced. The rotational drive motor of the sleeve can be made smaller and lighter, and a magnetic brush with a uniform height in the width direction is formed, which allows uniformly shaped developer to be conveyed to the main pole, reducing uneven image formation and background. It is possible to obtain the excellent effect of realizing high-quality development without stains.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view showing a magnetic brush developing device according to an embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional side views of a conventional magnetic brush developing device. In the figure, 1 is a sleeve, 2 is a main pole, 3 to 5 are sub poles,
6 is an electrostatic latent image support, 7 is a developer, 8 is a developer tip regulating blade, and 31 is a developer tip forming blade.

Claims (1)

[Claims] (1) The electrostatic image formed on the electrostatic latent image support is developed by sequentially transporting and circulating the developer using a transport device in which a magnetic pole for developing an electrostatic latent image and a magnetic pole for transporting the developer are built into a rotating sleeve. In the magnetic brush developing device, a developer regulating member is provided at a position facing the developer transporting magnetic pole of the rotary sleeve and regulates the amount of developer transported on the surface of the sleeve; and an electrostatic latent image development member of the rotary sleeve. and a developer forming member movably provided at a position facing the intermediate position between the magnetic pole for use and the magnetic pole for conveying the developer, and for pressing and leveling the developer on the surface of the rotating sleeve with a predetermined pressing force. Features a magnetic brush developing device.