JPS6283779A - Developing device - Google Patents

Abstract

PURPOSE:To miniaturize a device by positioning the homopolar magnetic pole adjoining in the circumferential direction to the scope of 20 deg. or above 60 deg. or below at the upstream side from the horizontal surface and on the other hand, positioning to the scope of 20 deg. or above 60 deg. or below at the downstream side from the horizontal surface. CONSTITUTION:For the central position of magnetic poles S2 and S3 the angles to a horizontal surface H through the center of a magnetic roller 7 are respec tively theta1 and theta2, and then, these angles theta1 and theta2 are set in the scope of 20 deg. <=theta1 and theta2<=60 deg.. The angles theta1 and theta2 are 20 deg. or below, and then, the developing agent supplying characteristic is held on the surface of a developing sleeve 6 again, and when the angle theta2 is 60 deg. or above, the developing agent supplying characteristic to the surface of the developing sleeve 6 is reduced. When the angle theta1 is larger than 60 deg., developing agent pooling X is larger between the developing sleeve 6 and a casing 3 where the magnetic pole S2 is located, and the collecting efficiency of the developing agent to an agitating roller 11 side is reduced. Thus, it is not necessary to provide the scraper, etc., to scrape the developing agent, and the developing device can be miniaturized.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a developing device that visualizes an electrostatic latent image formed on the surface of an electrostatic latent image carrier in an electrophotographic copying process or the like. be.

(Prior Art) Conventionally, as a developing method, a magnetic roller is placed on the outer circumferential surface of a developing sleeve made of aluminum or the like that has a fixed built-in magnetic roller.
A rotatably driven developer agitation roller (for example, a packet roller or a screw roller) holds the supplied developer and conveys the developer to a development area facing the electrostatic latent image carrier, thereby distributing the electrostatic latent image. A method has been proposed in which an electrostatic latent image carried on the surface of a carrier is visualized.

By the way, in general, in a developing device, since the toner concentration of the developer that has passed through the development area, that is, the developer after development, has decreased, this developer is once removed from the outer circumferential surface of the development sleeve and a new one is removed. It is necessary to supply the developer to the outer peripheral surface of the developing sleeve, so to speak, to replace the developer.

Conventionally, therefore, a method has been taken in which a scraper is brought into pressure contact with the outer circumferential surface of the developing sleeve on the downstream side of the developing area to scrape off the developer after development.

(Problems to be Solved by the Invention) However, in many cases, minute irregularities are formed on the outer circumferential surface of the developing sleeve by sandblasting or the like in order to improve developer conveyance. ,
When the scraper is pressed against the outer peripheral surface of the developing sleeve,
The wear of the developing sleeve is significant, and the developer is buried in the minute recesses at the press-contact portion, which solidifies over time, resulting in uneven developer-carrying properties on the surface of the developing sleeve.

Therefore, in devices that use a developing sleeve with minute irregularities on the surface, the developer whose toner concentration has decreased on the surface of the developing sleeve cannot be scraped off with a scraper, resulting in insufficient replacement of the developer. However, there has been a problem in that density unevenness and density reduction occur in the copied image.

Furthermore, in the conventional apparatus, the provision of the scraper restricts the installation position of the agitation roller, etc., resulting in an increase in the size of the apparatus.

(Means for solving the problems) The present invention has been made to solve the problems mentioned above.
N and S extending in the axial direction are provided on the outer circumference of the magnetic roller built into the developing sleeve of the conventional sleeve rotation type developing device.
The poles are sequentially magnetized in the circumferential direction, and the magnetic pole located at the part facing the stirring roller is a magnetic pole of the same polarity adjacent to the said magnetic pole in the circumferential direction, and the magnetic pole is located upstream of the same polar magnetic pole in the developer transport direction. The center is located within a range of 20° or more and 60° or more upstream in the developer conveyance direction than the horizontal plane with respect to the axis of the developing sleeve, while the center of the magnetic pole located on the downstream side is located upstream of the brush height regulating member. It is provided so as to be located downstream of the horizontal plane within a range of 20° or more and 60° or less, centering on the axis of the developing sleeve. (Example) Hereinafter, an example of the present invention will be described based on the drawings.

In FIG. 1, (1) shows a photoreceptor drum, and (2) shows a developing device according to the present invention. A developing sleeve (6), an agitation roller (11), and a supply roller (I6) are arranged sequentially rearward from the drum (1) side.

The photoreceptor drum (1) is a cylindrical body having an organic photoreceptor layer on its surface, and the surface is irradiated with light from an unillustrated optical system to form an electrostatic latent image at a circumferential speed of 150 mm/sec.
It can be rotated in the direction of arrow a.

The developing sleeve (6) is made of a non-magnetic conductive material (for example, aluminum) formed into a cylindrical shape, and the surface has minute irregularities formed by sandblasting.
) are opposed to each other with a phenomenon gap: Ds = 0.6 mm, and can be rotated at a rotation speed of 143.64 rpm in the direction of the arrow.

Further, the developing sleeve (6) has a built-in magnetic roller (7) having a magnetic pole on its outer circumference, and the magnetic force of the magnetic roller (7) causes a developer (usually made of a mixture of carrier and toner) to be applied onto the outer circumferential surface. ) is held and conveyed to the phenomenon area (A) facing the photoreceptor drum (+), and the electrostatic latent image formed on the photoreceptor drum (1) is developed.

Note that the lower part of the developing sleeve (6) is the casing (3).
and gap D=1. A spacing of Omm is maintained.

The magnetic roller (7) has an outer diameter of 24.5 mm, has magnetic poles (N, ~N3) and (S, -9,) alternately on the outer periphery, and has magnetic poles (N, ~N3) and (S, -9,) on the back side of the development area (A). The stirring roller (11)
Above and below the part closest to, there are magnetic poles of the same polarity (S2),
(S3) are provided adjacent to each other, and the magnetic pole (N1) is 900.
G, and the other magnetic poles (N2.N3.S,..., S,) are 500 to 600G.

Therefore, the magnetic force between the magnetic poles (S, ) and (S3) becomes zero, and the developer cannot be held on the developing sleeve (6).

Furthermore, the center positions of the magnetic poles (St) and (S,) are determined by the following angles (θ1), where the angles with respect to the horizontal plane (H) passing through the center of the magnetic roller (7) are (θI) and (θ,), respectively. ,
From the experiment, (θ,) is 20°≦01. θ is set within the range of ≦60°.

That is, when the angles (θl) and (θ, ) are 20° or less, the developer that passes through the development area (A) and is conveyed to the stirring roller (11) side is absorbed by the surface of the development sleeve (6). Coupled with the minute irregularities formed on the developing sleeve (6
) may be retained on surfaces.

In addition, if the angle (θ,) is 60° or more, the stirring roller (
11) The ability of the packet (I4) to supply the developer to the surface of the developing sleeve (6) is reduced.

Furthermore, if the angle (θυ is larger than 60°, the magnetic pole (
The developing sleeve (6) and the casing (3
) becomes large, and the efficiency of recovering the developer to the stirring roller (11) side decreases.

Furthermore, if the angle (θ, -z9.)>606,
The supply and recovery of the developer can be performed even better.

From the above, in this embodiment, the angles are set to 01-40°, θ, and -50°, as shown in FIG.

The stirring roller (11) has a blade portion (13) on the spindle (12).
A brush roller fitted with a stirring member with an outer diameter of 3
4 mm, and the rotation speed is 179.55 rpm in the direction of arrow C in the developer stirring conveyance path (10) (hereinafter referred to as stirring path).
The developer in the stirring path (lO) is mixed and stirred by the blade (13) and conveyed to the back side in the figure, and a part of the developer is developed in the packet (14). It is intended to be supplied to the surface of the sleeve (6).

Note that this stirring roller (II) is connected to the developing sleeve (6).
) and is installed approximately horizontally.

The supply roller (16) is a screw roller provided in a developer supply and conveyance path (hereinafter referred to as "supply path" below +5X) formed by a partition plate (5) provided behind the agitation roller (11), and is a screw roller provided in a developer supply and conveyance path (hereinafter referred to as a "supply path" below +5X). The toner and developer supplied from the replenishment tank are mixed and stirred while being conveyed toward the front in the figure.

Note that the partition plate (5) is formed with a passage that communicates the stirring passage (lO) and the supply passage (15) on the plane side and the rear side in the figure, and the stirring passage (IO) is connected by the stirring roller (11). O)
The developer generally sent to the back side passes through the passage and is connected to the supply passage (I
5), and the supply path (15) is passed through the supply roller (16).
) to the front side, pass through the passage on the plane side, and be fed into the stirring path (I0) again.

In addition, a height regulating member (8) is attached to the upper part of the casing (3).
is formed, and this brush height regulating member (8) is connected to the developing sleeve (6) on the downstream side of the magnetic pole (S3) with a spacing of brush height regulating gap Db=0.5 mm from the developing sleeve (6).
), and the amount of developer conveyed is regulated by cutting the developer conveyed by the developing sleeve (6) into spikes.

Furthermore, (9) is mylar to prevent powder smoke, and this mylar to prevent powder smoke (9) is made of polyethylene film (thickness 01 mm) and is attached to the upper part of the casing (3) facing the photoreceptor drum (1). This is to prevent powder smoke toner generated from around the developing sleeve (6) from scattering upward.

In the developing device (2) having the above configuration, the developer is supplied to the supply path (15) and the stirring path by the supply roller (16) and the stirring roller (II) while the toner is supplied from the toner supply tank (not shown). (10) is mixed and stirred while being conveyed, so that toner with improved charging potential is supplied to the surface of the developing sleeve (6) by the stirring roller (11).

Here, the transfer and reception of developer in the developing sleeve (6) will be explained based on FIG. 2.

Remaining on the surface of the developing sleeve (6) after passing through the phenomenon area (A) 4
- The developer with reduced toner content is in the development area (A).
The magnetic poles (S,
), it is released from the magnetic force and separates from the surface of the developing sleeve (6).

The developer separated from the developing sleeve (6) is collected on the stirring roller (11) side in the developer collection area (B), and mixed with the developer in the stirring path (10) by the stirring roller (11). be done.

At this time, the same polarity magnetic poles (S 2) and (S 3) are sufficiently opposed to each other, and the upstream magnetic pole (S2) is provided sufficiently below the horizontal plane, so that the toner concentration is The depleted developer is not retained on the surface of the developing sleeve (6) again.

On the other hand, the developer conveyed by the packet (14) of the stirring roller (11) is delivered to the developer sleeve (6) near the magnetic pole (S3) of the magnetic roller (7) in the developer supply area (C). The developing sleeve (6) transports the developing sleeve (6) in the direction of the arrow (b) and is subjected to development.

Note that since the magnetic pole (S3) is provided on the upstream side of the brush height regulating member (8), the developer supply performance is not impaired.

(Effects of the Invention) As is clear from the above description, the developing device according to the present invention sequentially attaches N and S poles extending in the axial direction on the outer circumference of the magnetic roller provided in the developing sleeve. The magnetic poles that are magnetized and located opposite the stirring roller are circumferentially adjacent magnetic poles of the same polarity, and the center of the magnetic pole located on the upstream side in the developer conveyance direction of the same polar magnetic poles is aligned with the axis of the developing sleeve. The center of the magnetic pole located on the downstream side is located on the upstream side of the height regulating member and centered on the axis of the developing sleeve. The structure is such that it is located downstream of the horizontal plane within a range of 20° or more and 60° or less.

Therefore, when the developed developer conveyed by the developing sleeve passes through the magnetic poles on the upstream side of the homopolar magnetized section, it easily separates from the developing sleeve surface, is collected by the stirring roller, and is mixed and stirred by the stirring roller. While being mixed with the existing developer, new developer is efficiently supplied to the developing sleeve by the stirring roller.

In addition, the spacing between the same-polarity magnetized parts is set to such an extent that the developer that has passed through the development area will not be retained on the development sleeve again, so it is possible to repeatedly use used developer with reduced toner concentration. do not have.

Therefore, it is possible to obtain a clear copy image without density unevenness or decrease in a degree.

Furthermore, since the magnetic poles of the homopolar magnetized part are oriented at an angle of 60 degrees or less with respect to the horizontal plane, there is no problem with the supply of developer to the developing sleeve, and the developer collection function to the stirring roller side is maintained. The developer can be recovered and supplied well without being damaged.

Moreover, since there is no need to provide a scraper or the like to scrape off the developer from the developing sleeve, it is possible to downsize the developing device and reduce manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a developing device according to the present invention, and FIG. 2 is a sectional view showing the magnetic pole arrangement of a magnetic roller and the flow of developer. 1. Photosensitive drum, 2. Developing device, 3. Casing, 4. Cover, 5. Partition plate,
6...Developing sleeve, 7...Magnetic roller,
11... Stirring roller, 6... Supply roller.

Claims (1)

[Claims] (1) A developing sleeve with a fixedly built-in magnetic roller and a developer stirring roller are housed in a substantially horizontal state, and
These are driven to rotate in the same direction, and the developer is supplied to the surface of the developing sleeve by the developer stirring roller, and the developer whose conveyance amount is regulated by the height regulating member is transferred to the developing device facing the electrostatic latent image carrier. The developing device is configured to cause the electrostatic latent image to be conveyed from above to below in a region to visualize the electrostatic latent image carried on the surface of the electrostatic latent image carrier, the developing device having an axial direction on the outer peripheral part of the magnetic roller. At the same time, the N and S poles extending in the area are sequentially magnetized in the circumferential direction, and the magnetic poles located at the portion facing the stirring roller are made to be circumferentially adjacent same-pole magnetic poles, and the developer conveyance of the same-polar magnetic poles is performed. The center of the magnetic pole located on the upstream side in the direction is located within a range of 20° or more and 60° or less upstream in the developer conveying direction from the horizontal plane, centering on the axis of the developing sleeve,
The center of the magnetic pole located on the downstream side is located on the upstream side of the brush height regulating member and within a range of 20° or more and 60° or less downstream of a horizontal plane about the axis of the developing sleeve. A developing device characterized by: