JPS6238488A - Dry type developing device - Google Patents

Abstract

PURPOSE:To improve the efficiency of agitation of a developer by arranging a developer leakage preventing plate opposed to a developing sleeve on the slightly upstream side of a magnetic pole and a developer agitating plate opposed to the developing sleeve at the almost center between two magnetic poles on the downstream side of a toner feeding part. CONSTITUTION:In the agitating operation of the developer, the developer pushed up sharply by the main developer agitating plate 7 is again returned to the surface of the developing sleeve 5 by the magnetic pole of which the center of magnetic force is positioned on the slightly downstream side of the leakage preventing plate 8 and prevented from being dropped to the feeding roller 11 side. The developer of which nap height is regulated through a gap between the agitation plate 7 and the developing sleeve 5 forms a magnetic brush on the surface of the sleeve 5 and the magnetic brush slides the surface of a photosensitive drum 1 at the opposite part between the sleeve 5 and the drum 1 to develop an electrostatic latent image formed on the surface of the drum 1 in the exposing process.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a dry developing device used in an electrophotographic copying process, etc. (Prior art and its problems) Conventionally, there have been various types of developing devices. A two-component developer consisting of a magnetic carrier and an insulating toner is generally conveyed along the circumferential surface of a developing sleeve. In this type of dry developing device,
A magnetic roller with an N pole and an S pole magnetized sequentially in the circumferential direction on the outer circumference is built into the developing sleeve, and the magnetic force of this magnetic roller attracts the developer in a brush-like manner to the circumferential surface of the developing sleeve.
The brush-shaped developer is stirred and conveyed in one direction by the movement of the magnetic field caused by the rotation of the magnetic roller.

However, when trying to convey the developer based on the rotation of the magnetic roller, the magnetic roller needs to be rotated at a fairly high speed, which increases the load on the drive system of the developing device.
This goes against the recent trend of making copying machines smaller, lighter, and more compact.

Therefore, the magnetic roller is fixed, a toner supply roller is attached to a toner storage tank attached to the side of the developing sleeve, and the toner supply roller directly supplies the toner in the toner storage tank onto the circumferential surface of the developing sleeve. , the carrier magnetically attracted on the developing sleeve and the toner are mixed based on the rotation of the developing sleeve to prepare a magnetic developer, and this developer is used to develop an electrostatic latent image. An electrolatent image developing device is provided.

By the way, in this method, how can insulating toner be efficiently mixed and stirred with magnetic carrier on a small circumferential surface of the developing sleeve from the toner supply section to the developing area, and in a short time to be suitable for development? The challenge was how to improve the charging potential to this level.

For this reason, it may be possible to install a developer regulating plate between the toner supply section and the development area to improve the agitation efficiency of the developer. This may cause the toner to flow backwards, causing toner to accumulate in the toner supply section, or toner containing a carrier to be mixed into the toner replenishment tank, and the location of its installation has been a problem.

(Means for solving problems) Is the present invention 1i? This was done to solve the problem mentioned above. A magnet with rU number of magnetic poles formed in the circumferential direction is fixed inside the developing sleeve, and only the developing sleeve is rotated. A dry type developing device in which insulating toner is directly supplied to a carrier, and the magnetic carrier and insulating toner are mixed and conveyed on a developing sleeve, between a toner supply section and a developing area,
and ifj, on the downstream side of the toner supply section, a developing agent spill prevention plate facing the developing sleeve on the slightly -L flow side of the magnetic poles, and a developing agent spill prevention plate facing the developing sleeve approximately in the center between two adjacent magnetic poles; This is equipped with a single developer stirring plate.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, (1) represents a photoreceptor drum, (2) represents a dry developing device according to the present invention, and the photoreceptor drum (1) represents a dry developing device according to the present invention.
) can be rotated in the direction of arrow (a) at a constant speed.

The developing device (2) coaxially accommodates a magnetic roller (6) having multiple poles on the outer periphery within a cylindrical developing sleeve (5) made of a conductive non-magnetic material. It is installed in the opening (3a) of the developer tank (3) so as to be close to the surface of the photoreceptor drum (1), and the toner storage I! (4,
), and the magnetic developer consisting of insulating toner and magnetic carrier is rotated in the direction of rotation of the developing sleeve (arrow (b)
) direction) at the same speed as its rotational speed. A main developer stirring plate (7) and a spill prevention plate (8) are installed around the developing sleeve (5).

The main developer agitating plate (7) is made of a non-magnetic material, and extends toward the center of the image sleeve (5).
) with the developer flow facing upwards (
5), where the restraining force of the developer by the magnetic pole provided on the magnetic roller (6) is the smallest, that is,
The developing sleeve (5) is located approximately in the center between two adjacent magnetic poles.
The spill prevention 1J: plate (8
) and the spill prevention plate (8) forming the empty part 11j (9) is made of a non-magnetic material like the main developer stirring plate (7).
5), it is installed close to the developing sleeve (5) slightly upstream from the center of the magnetic pole of the magnetic roller (6).

On the other hand, in the side opening (4a) in the toner storage tank (4), a toner supply roller (I) is placed close to the circumference of the developing sleeve (5) and in synchronization with the rotation of the developing sleeve (5). It is installed so that it can be rotated in the direction of arrow (c). Note that this toner supply roller (11) is made of a conductive non-magnetic material,
For example, it is made of aluminum, and minute irregularities of about 50 μm are formed on its surface by blasting.

A blade (12) and a seal member (13) made of a non-magnetic material are in contact with the toner supply roller (ll) above and below the opening (4a) of the toner storage tank (4), respectively. ) are opposed to the rotation direction of the toner supply roller (11), and the seal member (13) is attached along the rotation direction of the toner supply roller (12). The blade (12) has a thickness of 2 to 3 mm and a rubber hardness of 7.
The toner supply roller (1
1) The elastic deflection claw at the contact part with 05~! , Omm.

The operation of the developing device having the above configuration will be described below.

First, a starter made of a mixture of magnetic carrier and insulating toner is held in the developing sleeve (5), and the starter is stored in the space (9).
) is loaded with insulating toner.

In this state, development can be performed by the developing device (4). Note that at this time, only a magnetic carrier may be loaded in the space (9) instead of the 11th starter.

Here, the toner supplied to the developing sleeve (5) based on the rotation of the toner supply roller (11) in the direction of arrow (C), together with the carrier held on the circumferential surface of the developing sleeve (5), Based on the rotation, it is conveyed in the direction of arrow (b) and reaches the space (9).

In the space (9), the developer consisting of carrier and toner is partially blocked by the main developer stirring plate (7), and is pushed by the magnetic developer conveyed later.
It warps up along the main developer stirring plate (7).

This developer then rotates counterclockwise due to the magnetic force of the magnetic roller (6) and the action of the heavy horns and falls onto the developing sleeve (5), and is again moved to the main developer stirring plate (7).
A part of the developer passes through the gap between the main developer stirring plate (7) and the phenomenon sleeve (5) and is carried downstream, and the remaining developer is transferred to the main developer stirring plate (7) again. It is blocked and stirring is performed continuously.

In addition, during the developer stirring operation, the developer pushed up by the main developer stirring plate (7) is returned to the developing sleeve ( 5) While being returned to the surface, the supply roller (11) is
This prevents it from falling to the side.

Next, the developer whose brush height is regulated through the gap between the main developer stirring plate (7) and the developing sleeve (5) forms a magnetic brush on the surface of the developing sleeve (5), and this magnetic brush Opposing part between the developing sleeve (5) and the photoreceptor drum (1) (
The surface of the photoreceptor drum (1) is rubbed in the development area (A)), and the electrostatic latent image formed on the surface in an exposure step (not shown) is developed and visualized.

After passing through the development area (A), the development sleeve (
The developer remaining on the circumferential surface of the toner supply roller (1)
1), where new toner is supplied, and then reaches the space (9) again where it is mixed and stirred and subjected to development.

Incidentally, the toner supply operation by the toner supply roller (11) is performed as follows.

First, the toner contained in the toner storage tank (4) enters a minute recess on the circumferential surface of the toner supply roller (11).
Based on the rotation of the roller (11) in the direction of arrow (C), it is transported in the same direction. Then, the blade (12) scrapes off the excess adhered toner, reaches a position facing the developing sleeve (5), and supplies a fixed amount of toner to the developing sleeve (5).

In addition, the developing sleeve (5) and the toner supply roller (11)
The toner in the magnetic developer on the developing sleeve (5) is electrostatically maintained at a constant value based on the potential difference between the developing sleeve (5) and the developing sleeve (5).

Further, the potential difference is determined by the correlation between the bias voltage applied to the toner supply roller (II) and the voltage value of the developing bias.

FIG. 2 shows another embodiment of the developing device according to the present invention,
In general, this developing device has developer uniformly extending in the axial direction of the developing sleeve (5) between the main developer stirring plate (7) and the spill prevention plate (8) of the first embodiment. An auxiliary developer stirring plate (1) has a slit-like opening (14a) through which it can pass.
4) was installed.

Note that the tips of the main and auxiliary developer stirring plates (7) and (14) are arranged so that they are located approximately in the center between two adjacent magnetic poles provided on the magnetic roller (6), and the spill prevention plate ( 8
) is attached so as to be located slightly upstream from the center of the magnetic pole of the magnetic roller (6), as in the first embodiment.

In addition, an auxiliary developer stirring plate (14) and a spill prevention plate (8) are also included.
The main developer stirring plate (7) and the auxiliary developer stirring plate (14) form a space (lO).

The movement of the developer in the space (9) is similar to the first embodiment, in which the magnetic developer rotates counterclockwise on the upstream side of the auxiliary developer stirring plate (14) in the conveying direction. While the developer is being stirred, the auxiliary developer stirring plate (
A part of the magnetic developer pushed up along the slit-shaped opening (14) provided in the auxiliary developer stirring plate (14)
4a) and reaches the downstream space (lO).

Further, a part of the magnetic developer stirred in the space (9) is transferred to the auxiliary developer stirring plate (
14) and the developing sleeve (5), and is transported to the space (lO).

The developer transported to the space (10) in this way is
On the upstream side of the main developer stirring plate (7), the developer is mixed and stirred by rotating counterclockwise similarly to the space (9).

The magnetic developer well stirred in the spaces (9) and (IO) passes through the gap between the main developer stirring plate (7) and the developing sleeve (5), and the height of the magnetic developer is regulated. A magnetic brush is formed, and this magnetic brush rubs the surface of the photoreceptor drum (1) in the development area (A) to develop and visualize the electrostatic latent image on the surface.

After being subjected to development, the developer remaining on the circumferential surface of the developing sleeve (5) reaches the part facing the toner supply roller (11), where new toner is replenished, and then it returns to the space (
9), (IO) is mixed and stirred and subjected to development.

(Effects of the Invention) As is clear from the above description, the dry developing device according to the present invention has a structure that is located between the toner supply section and the development area, and on the downstream side of the toner supply section, and slightly upstream of the magnetic pole. Since the structure is provided with a developer spill prevention plate facing the developing sleeve and at least one developer stirring plate facing the developing sleeve approximately in the center between two adjacent magnetic poles, the developer is not supplied from the toner supply section. In the short time it takes to reach the development area, it is sufficiently mixed with the carrier and agitated, increasing the charging potential until it is suitable for development. can be achieved.

In addition, the developer is well stirred by the developer stirring plate, and the developer pushed up along the developer stirring plate is prevented from falling into the toner supply section by the spill prevention plate. Because the magnetic force located on the downstream side of the spill prevention plate reliably returns the developer onto the developing sleeve, the developer does not accumulate in the toner supply section, and the developer enters the recess on the surface of the toner supply roller and stores the toner. There is no chance of it getting mixed into the tank.

Therefore, there is no possibility that the amount of magnetic developer on the developing sleeve will decrease or that the developer that has entered the toner storage tank will damage the toner regulating member (blade, sealing material), making it possible to supply toner stably. can.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of a dry developing device according to the present invention, and FIG. 2 is a sectional view showing another embodiment. 5...Developing sleeve, 6...Magnetic roller, 7...
Main developer stirring plate, 1. Spill prevention plate, 11. Toner supply roller, 14. Auxiliary developer stirring plate, A. Developing area.

Claims (1)

[Claims] (1) A magnetic carrier that has a developing sleeve and a magnet that is provided inside the developing sleeve and forms a plurality of magnetic poles in the circumferential direction of the developing sleeve, and is magnetically attracted to the circumferential surface of the developing sleeve. On the other hand, by supplying insulating toner from the toner supply section, a magnetic developer consisting of a mixture of magnetic carrier and insulating toner is prepared on the circumferential surface of the developing sleeve, and this magnetic developer is used to fill the developing area. The developing device is configured to develop an electrostatic latent image using a toner supply section, and between a toner supply section and a development area, and on the downstream side of the toner supply section, the development sleeve and the development sleeve are sequentially arranged slightly upstream of the magnetic pole. The opposing developer spill prevention plate and the adjacent two
1. A dry-type developing device comprising at least one developer stirring plate that faces the developing sleeve approximately at the center between the two magnetic poles.