JPH01321459A - Developing device - Google Patents

Abstract

PURPOSE:To stably supply a prescribed amount of developer to a developing region by making the polarities of magnetic poles provided inside developing sleeves arrayed continuously different and making magnetic poles in a developer receiving region ferromagnetic and opposite to those in a developer delivery region. CONSTITUTION:The two regions are inside the adjacent developing sleeves 37 and 39 so as to face them: one is the developer receiving region (region where the magnetic poles N3 and N5 locate) and the other is the developer delivery region (region where the magnetic poles S3 and S5 locate). The magnetic poles N3 and N5 provided in the former region are opposite to those S3 and S5 provided in the later region. Namely, the magnetic poles N3 and N5 in the developer receiving region are ferromagnetic and opposite to the magnetic poles S3 and S5 in the facing developer delivery region incorporated inside the adjacent developing sleeve. Thus, developer which is conveyed to the develop ing region can be stably supplied.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a method for developing an electrostatic latent image formed on the surface of an electrostatic latent image carrier using a two-component developer consisting of a toner and a carrier. The present invention relates to a developing device.

(Prior art and its problems) Conventionally, a developing device in which a developing sleeve containing a plurality of fixed magnets is continuously arranged on the side of an electrostatic latent image carrier is disclosed in Japanese Patent Laid-Open No. 52-17829 and other publications. Proposed.

According to the above-mentioned developing device, 2 particles consisting of toner and carrier
The component developer is held in the form of a magnetic brush on the outer periphery of the developing sleeve along lines of magnetic force generated from the magnet. Also,
The developer is circulated and conveyed around the developing sleeves based on the rotation of the developing sleeves, and during the conveyance process, the developer comes into contact with the surface of the electrostatic latent image carrier in a plurality of development areas,
The electrostatic latent image formed on the surface of the electrostatic latent image carrier is visualized.

By the way, in the developing device, as shown in FIG. 3, if the arrangement of the magnetic poles or the magnetic force balance is poor in the area where the developing sleeves (51) and (52) face each other, the developing sleeve (51)
, (52), that is, through the area (55), various problems occur.

Specifically, when the developer passes through the area (55), the amount of developer conveyed to the development area (53) is reduced to the upstream development area (
54), which causes inconveniences such as the toner adhering to the surface of the electrostatic latent image carrier (200) being scraped off, degrading the image quality, and causing carrier adhesion to the electrostatic latent image carrier (200). .

Furthermore, since the developer is subjected to conveying forces in different directions at the opposing portions of the area (55), the developer may become clogged there and an unreasonable load may be applied to the drive system of the developing sleeves (51) and (52). , the developer may stop flowing and leak outside.

Furthermore, it is difficult to quantitatively grasp the amount of developer conveyed through the area (55), and the design of the developing device, especially the development between the developing sleeves (51), (52) and the electrostatic latent image carrier (200), is difficult. It becomes very difficult to design the gap and the gap between the developing sleeves.

Furthermore, the toner is supplied directly to the developer circulating flow surrounding the developing sleeves (51) and (52), and the toner and carrier are mixed in the flow to charge the toner.
The toner is supplied to the electrostatic latent image carrier in an uncharged state, causing fogging on the image and resulting in poor image quality.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems, and will be described with reference to FIG. 1 showing one embodiment. Multiple developing sleeves (3
7) and (39) are arranged continuously, and these developing sleeves (37) and (39) are rotated to transfer the developer between adjacent developing sleeves, and the developing sleeve (37)
), (39), a developing device that forms a circulating flow of developer surrounding the developing sleeves (37), (39) includes a region facing the adjacent developing sleeves (39), (37) inside the developing sleeves (37), (39). and the developer receiving area [magnetic pole (N3), (
area where the magnetic pole (s
3), (S
(SS)), and these magnetic poles have different polarities, and the magnetic poles (N3) and (SS) of the developer receiving area are provided.
N6) is ferromagnetic and has opposite polarity to the magnetic poles (S5) and (S3) of opposing developer receiving areas built in adjacent developing sleeves.

(Function) According to the developing device (1), as shown in FIG. 2, the two-component developer consisting of toner and carrier has a flow of
The developing sleeve (37
), (39).

Then, in the opposing area (F) between the developing sleeves (37) and (39), the developer that has flowed over the developing sleeve (37) and has been conveyed along (N,) and transferred to the developing sleeve (39). Here, the magnetic pole (N,) provided in the developer receiving area is more ferromagnetic than the opposing magnetic pole (S,) in the developer delivery area, and the magnetic pole (N3) is provided in the opposing area (F). (N5), the magnetic poles (N3), and (N5) form a repulsive magnetic field, so the developer transfers to the developing sleeve (39) without passing through the facing area (F).

On the other hand, the developer flowing on the developing sleeve (39) and being transported along the magnetic pole (N
, ) and transferred to the developing sleeve (37). Here, as described above, the magnetic pole (N,) in the developer receiving area is more ferromagnetic than the magnetic pole (S,) in the developer delivery area, and due to the repulsive magnetic field formed in the opposing area (F),
The developer is transferred to the developing sleeve (37) without passing through the facing area (F).

(Example) The present invention will be described below with reference to the accompanying drawings.

(2) Structure of developing device [1] Schematic structure FIG. 1 shows a developing device (1) according to the present invention, and this developing device (1) roughly consists of a toner replenishing device (2) and a developing device (3). It consists of

[Mu] Toner replenishing device (2) In the toner replenishing device (2), the cartridge accommodating section (4)
A toner cartridge (15) is installed in the.

The cartridge accommodating portion (4) has a rear wall (7), a support member (6a), ( 6b), (6C
) is passed over the rack, and a substantially semicircular bottom plate (9) is supported by the supporting members (6a), . . . , (6c). In addition, the bottom plate (9)
The tip of the arm (11) is fixed to the arm (l l), and the arm (11) is attached to the side plate (5), (5) with a shaft (to), (10
) It is rotatably attached via the. In addition, the bottom plate (9
One end of a spring (12) is locked to the bottom of the toner cartridge ( ) and biased in the direction of arrow (a).
15) is not installed. It moves in the direction of arrow (a) by the biasing force of the spring (12) to close the toner supply port (27) of the developing device (3), which will be described later.

The toner cartridge (15) has a stirring blade (18) inside a cylindrical body (16) with both ends closed through a support shaft (17).
The main body (16) has an opening (19) formed along the axial direction.

The toner cartridge (15) has side plates (5), (5)
), the support shaft (17) is lowered along the guide portions (13), (13) formed in Mouth (2
7).

When the toner cartridge (15) is installed, the bottom plate (9)
) moves in the direction of the arrow (a'') about the axis (lO) against the biasing force of the spring (12), and the toner supply port (27) is opened.

Note that the toner cartridge (15) is prevented from falling off by a lock portion (8) provided on the rear wall (7).

Further, when the toner cartridge (15) is installed, the handle (60) located in the cartridge accommodating portion (4) is rotated in the direction of arrow (h) and placed out of the way.

(iii) Developing device (3) The developing device (3) is roughly composed of a toner supply section (20), a developing section (35), and a developer stirring section (45).

(a) Toner supply section (20) The toner supply section (20) receives the toner supplied to the developing device (2) from the toner cartridge (15) of the toner supply device (2), and supplies the toner to the developing section (35). It is intended to supply

In the toner supply section (20), between the bottom frame (21) constituting the developing device (3) and the partition walls (49) and (50) that partition the developer stirring section (45), A toner supply roller (22) is arranged at the front, and a toner hopper (25) having a stirring blade (26) is formed at the rear.

The toner supply roller (22) has minute irregularities formed on its outer circumference, and partition walls (
50), the blade (2) attached to the bottom frame (21)
3) The tips of the toner outflow prevention plates (24) are pressed into contact with each other.

Note that the toner supply roller (22) is connected to an AC power source (31).
) and the recovery bias voltage (Vs) (
=Vrms+Vss) is applied.

The toner hopper (25) has a slope (28) going diagonally upward.
is connected to the toner supply port (27) via the ramp (
28) is rotatably provided with a toner empty detection device (30). In addition, a toner spill prevention cant (29) is attached to the lower edge of the toner supply port (27).
The tip contacts the outer periphery of the toner cartridge (15) to prevent toner from spilling out from the gap between the developing device (3) and the toner cartridge (15).

(b) Developing section (35) The developing section (35) receives the toner supplied from the toner supply section (20), and also transfers the toner and carrier to the photosensitive drum (100), which is an electrostatic latent image carrier. Toner is supplied to the electrostatic latent image formed on the surface.

In the developing section (35), the space formed between the bottom frame (21) and the sleeve cover (36) includes a developing sleeve (37) at the bottom and another developing sleeve (39) at the top.
), the lower developing sleeve (37) faces the toner supply roller (22) with a predetermined minute gap, and the upper developing sleeve (39) has a sleeve cover (36) on the top. The height regulation plate attached to the rear (
The tips of 41) are opposed to each other with a predetermined height regulating gap.

In addition, the developing sleeves (37) and (39) are connected to a DC power source (4).
2), development bias voltage (V b +) from (43),
(V b 2) is applied to each. Further, the developing sleeves (37) and (39) include the developing sleeves (37) and (39).
Magnet bodies (38), (40) independently from (37), (39)
) are housed in a fixed state.

The magnet body (38) has magnetic poles (N,), ~, (N,), (
S, ), ~.

(S, ), and the magnetic pole (Sl) is a photoreceptor drum (100
), the magnetic pole (N2) is the toner supply roller (22
) is located opposite the Moreover, the magnetic poles (S,) and (N,) are arranged in the opposing region (F) of the developing sleeves (37) and (39), and are The magnetic pole (S,) is located on the upstream side, and the magnetic pole (N,) is located on the downstream side. In addition, the magnetic pole (N
I) and (N2) are respectively magnetic poles (Sl) and (N2),
It is arranged between the magnetic pole (N2) and the magnetic pole (S,).

The other magnet (40) has magnetic poles (N a)+~, (N
a).

(N4), ~, (S7), the magnetic pole (N,) faces the photoreceptor drum (100), and the magnetic pole (N6) and (S7)
are adjacent to each other and face the developer stirring section (46). Further, the magnetic poles (s S) and (N 6) are arranged in the facing area (F), and are arranged in the rotation direction of the developing sleeve (39) [arrow (f)
direction], the magnetic pole (S, ) is on the upstream side, and the magnetic pole (S, ) is on the downstream side.
N, ) are arranged, with the magnetic pole (S,) facing the magnetic pole (N, ) and the magnetic pole (N5) facing the magnetic pole (N3). moreover,
The magnetic pole (N6) is located slightly upstream of the facing part of the height regulating plate (41), and the magnetic pole (N4)
) and (N6).

The magnetic pole in the opposing region (F) is the magnetic pole (N, )
is more ferromagnetic than the magnetic pole (s), (SS), and the magnetic pole (N
, ) are more ferromagnetic than the magnetic poles (SS).

Specifically, the magnetic poles (N 3) and (N 5) are about 600G [
G n Gauss] or more, the magnetic poles (S 3) and (S 5) are approximately 4
It is desirable to set the magnetic force to 00G and provide a magnetic force difference of about 200G or more between the magnetic poles (N 3), (N 5) and the magnetic poles (s 3), (S 5).

(c) Developer stirring section (45) The developer stirring section (45) mixes the toner supplied from the toner supply section (20) to the developing section (35) with the developer whose toner concentration has decreased. The developer is raised to a predetermined concentration and a developer suitable for development is prepared.

In the developer stirring section (45), a stirring tank (46) is formed behind the developing sleeve (39), with an upper frame (47) at the top and partition walls (49) and (5) at the back and bottom.
A packet roller (51) is housed therein, and the tip of the partition wall (5o) is covered with a developing sleeve (3o).
7) and (39) are opposed to each other.

In addition, the stirring tank (46) is equipped with a lid (4) of the upper frame (47).
8) is opened and a starter containing toner and carrier mixed in a predetermined ratio is loaded.

Further, a two-component developer containing a mixture of toner and carrier is held on the outer periphery of the developing sleeves (37) and (39).

(2) The developing device (1), which has a configuration above the operation of the developing device, is equipped with a stirring blade (18) when installed in an image forming apparatus such as a copying machine.

(26), toner supply roller (22), developing sleeve (
37), (39), and a packet roller (5I) are each drivingly connected to a drive system (not shown).

When the developing device (1) starts driving, the stirring blade (18) moves in the direction of the arrow (b) in the toner cartridge (15).
The toner rotates in the direction of the opening (
19), the toner is fed into the ramp (28) via the toner supply port (27).

The toner sent to the toner hopper (25) is transported by a stirring blade (
26) is mixed and conveyed forward while being mixed based on the rotation in the direction of arrow (d), and is held on the surface of the toner supply roller (22) in the area (A) near the outer circumference of the back surface of the toner supply roller (22). Based on the rotation, it is transported in the direction of arrow (c), and the amount of transport is regulated at the portion facing the blade (23). The toner scraped off from the outer periphery of the toner supply roller (22) by the tip contact portion of the blade (23) stays in the toner hopper (25). On the other hand, the blade (2
The toner that has passed through the tip contact part of 3) is transferred to the developing sleeve (
37) and the toner supply roller (22) are conveyed to the toner supply area (B) where they face each other, and here the developing sleeve (37)
) scraping action of the carrier and developer being conveyed in a magnetic brush state based on the rotation in the direction of arrow (e);
Development bias voltage (Vb+) and recovery bias voltage (Vs
s) (=Vrms+Vs s) (=Vrms+Vs s).

In addition, in the toner supply area (B), in parallel with the toner supply operation, an operation is performed to collect excess toner on the developing sleeve (37) to the toner supply roller (22) by the electrostatic attraction force, and the developing sleeve (37) The toner concentration of the developer held above (the content ratio of toner to carrier) is maintained at a predetermined value.

Further, the toner collected by the toner supply roller (22) is conveyed in the direction of arrow (c), and the toner is transported to the toner outflow prevention plate (24).
) and are collected in the toner hopper (25).

As shown in FIG. 2, the toner supplied to the surface of the developing sleeve (37) is taken into the developer held in a magnetic brush state along the lines of magnetic force, and is mixed with the developer while being mixed with the developer. Based on the rotation of the developer, the developer is transported in the direction of arrow (e) along the flow (3), and in the transport process, the developer and toner are transported based on the rotational force of the developing sleeve (37) and the magnetic force of the magnet (38). They are mixed microscopically to improve their respective potentials.

The developer flowing on the developing sleeve (37) and being conveyed along the direction (■) reaches the front side of the opposing area (F) between the developing sleeves (37) and (39), and then reaches the magnetic pole ( S5) and transferred onto the developing sleeve (39).

Here, the magnetic pole (N,) of the developer receiving area that receives the developer from the developing sleeve (37) is connected to the developing sleeve (39).
Since the developer is more ferromagnetic than the magnetic pole (S,) in the developer transfer area where the developer is delivered, the developer transported to the area opposite the magnetic pole (S,) is attracted to the magnetic pole (N,). All are transferred onto the developing sleeve (39).

It should be noted that repulsive magnetic fields are formed between the developing sleeves (37) and (39) by the magnetic poles (N,) and (N,), and by the magnetic poles (S3) and (S,), respectively. As a result, all the developer is transferred to the upper developing sleeve (39) without passing through the facing area (F).

The developer transferred to the developing sleeve (39) is conveyed in the direction of the arrow (f) along the flow ■ based on the rotation of the developing sleeve (39), and is formed between the magnetic poles (S6) and (S7). The developing sleeve (39) is separated from the outer periphery of the developing sleeve (39) at the non-magnetic pole portion (C) and collected in the stirring tank (46).

Note that the developer conveyed from the direction of arrow (e) along the developing sleeve (37) suddenly changes direction in the facing area (F) and heads in the direction of arrow (f), so the developer is Mix and stir well.

In the stirring tank (46), as shown in FIG. 1, the developer is transported in the direction of arrow (g) based on the rotation of the packet roller (51), and the toner and carrier are macroscopically mixed and stirred while circulating. Ru.

As shown in FIG. 2, the developer being mixed and stirred in the stirring tank (46) is transported toward the developing sleeve (39) along the flow (2), and a portion of the developer is mixed and stirred by the magnetic pole (S7).

(S6) is held on the surface of the developing sleeve (39) again and conveyed in the direction of arrow (f), and the height regulating plate (
41), the conveyance amount is regulated at the opposite part.

The developer that has passed through the portion facing the height regulating plate (41) is conveyed in the direction of the arrow (f) in the state of a magnetic brush, and passes through the portion facing the magnetic pole (S,) along the flow ■ to the photoreceptor drum (100).
In the developing region (D) where the developing sleeve (39) and the developing sleeve (39) face each other, the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum (100) is rubbed and visualized as a toner image.

The developer that has passed through the development area (D) is transferred to the development sleeve (3).
9) is further conveyed in the direction of the arrow (f), and at the part facing the developing sleeve (37), it is pulled by the magnetic pole (N,) of the magnet body (38) along the flow ■, and the developing sleeve (37).

In addition, the developing sleeves (37) to (39) explained earlier
Similar to the transfer operation of the developer to
is more ferromagnetic, and magnetic poles (S, ) and (S3
), (N,) and (N,), the developer is smoothly transferred from the developing sleeve (39) to (37), and the opposite area ( F) will not be passed.

The developer transferred to the surface of the developing sleeve (37) is conveyed in the direction of arrow (e) based on its rotation, and is transferred to the developing area (37).
In step E), the toner comes into contact with the electrostatic latent image on the photoreceptor drum (100) again, and toner is again supplied to the toner image developed in the development area (D). Therefore, toner is replenished even in the developing area (D) where the toner supply was insufficient, and density unevenness and white spots due to insufficient toner supply do not occur.

The development in the development areas (D) and (E) is performed using the development bias voltages (V b 2) and (V b l) applied to the development sleeves (39) and (37) and the photoreceptor drum (1).
00) based on the potential difference with the surface potential.

The developer that has passed through the development area (E) is conveyed along the flow (2) to a portion facing the toner supply roller (22), where an amount of toner corresponding to the amount consumed by development is supplied.

The supplied toner is conveyed along the outer peripheral surfaces of the developing sleeves (37) and (39) as described above.

By repeatedly performing development as described above, the toner in the toner cartridge (15) is gradually consumed, and along with this, the toner hopper (25) and ramp (28) are consumed.
) decreases, the toner empty detection device (30) rotates in the direction of arrow (i) to detect that the toner cartridge (15) should be replaced, that is, the toner empty state. Ru.

Then, by installing a new toner cartridge (15) containing sufficient toner, the toner empty state is resolved.

In the above explanation, the developing device (1) was equipped with two developing sleeves (37) and (39), but the developing device (1) was equipped with two developing sleeves (37) and (39). The present invention is also applicable to devices.

Further, in the above embodiment, the developing sleeves (37), (39)
), the present invention is applied to a developing device that supplies toner into the flow of developer that is being conveyed on the surface of the sleeve. The present invention is also applicable to things.

Further, in the above embodiments, the case where a photoreceptor drum (+00) is used as an electrostatic latent image carrier is shown, but even if the image forming apparatus uses a belt type photoreceptor, a developing apparatus to which the present invention is applied may be used. can be used.

(Effects of the Invention) As is clear from the above description, in the developing device according to the present invention, there is provided a developer receiving area in the inside of the continuously arranged developing sleeves, the area facing the adjacent developing sleeves. A magnetic pole is provided in each of the developer transfer area and the developer transfer area, and these magnetic poles are of different polarity, and the magnetic pole of the developer receiving area is opposite to the magnetic pole of the opposing developer transfer area built in the adjacent developing sleeve. It has polar performance and is ferromagnetic.

Therefore, the developer conveyed to the opposing portion of the developing sleeve is attracted by the magnetic poles accommodated in the developer receiving area and transferred to the surface of the opposing developing sleeve.

In addition, since the same poles are diagonally opposed to each other in the developing sleeve opposing portion and a repulsive magnetic field is formed between them, the developer does not enter between the developing sleeves.

Therefore, a predetermined amount of developer can be stably supplied to the development area, and a smooth flow of the developer can be formed. Furthermore, since the amount of developer to be transported can be easily grasped, it becomes easier to design the development gap and the gap between sleeves. Furthermore, in a developing device that mixes toner and carrier at the outer periphery of the developing sleeve, as in the embodiment, uncharged toner is not immediately conveyed to the developing area through the sleeves, and the sleeve Since the materials are sufficiently mixed at the outer periphery before being subjected to development, a high-quality image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the developing device according to the present invention, FIG. 2 is a cross-sectional view showing the state of developer conveyance on the developing sleeve, and FIG.
The figure is a cross-sectional view showing the arrangement of magnetic poles in a conventional developing device. ■...Developing device, 2...Toner supply device, 3...
Developing device, 20... toner supply section, 35... developing section,
37.39...Developing sleeve, 38.40...Magnet, 45...Developer stirring section, +00...Photosensitive drum, N1. ~． N6, Sl, ~+S7...Magnetic pole. Patent applicant Minolta Camera Co., Ltd. Agent Patent attorney Haka Aoyama Figure 2

Claims (1)

[Claims] (1) A plurality of developing sleeves each having a built-in magnet are arranged in succession, these developing sleeves are rotated to transfer the developer between adjacent developing sleeves, and the developer is circulated around the developing sleeves. In the developing device that forms a flow, magnetic poles are provided inside the developing sleeve in a region facing an adjacent developing sleeve, a developer receiving region and a developer delivery region, and these magnetic poles have different polarities. In addition, a developing device characterized in that the magnetic pole of the developer receiving area is ferromagnetic and has a reverse polarity with respect to the magnetic pole of the opposing developer transfer area built in an adjacent developing sleeve.