JPH01167866A - Developing device - Google Patents

Abstract

PURPOSE:To miniaturize the device by providing a carrying capacity reducing part on an area except both end parts of a developer carrying means. CONSTITUTION:A developer is allowed to circulate and carried through carrying paths 6, 7 and 8 in a developing device, and supplied to the surface of a developing sleeve. The developer carried to the carrying path being in the rear of the carrying path 7 being in the rear of the carrying path 6 being adjacent to the sleeve 17 passes through an area X1 and when it reaches an area X2 (developer carrying capacity reducing part), since a blade pitch delta2 is made narrower than the areas X1, X3, a carrying speed of the developer decreases and the developer is accumulated. In this state, the fluctuation quantity of the developer contained in the inside of the developing device is nearly absorbed as a fluctuation value of the developer accumulation quantity of the area X2, by which a developer level of other area becomes roughly constant. Also, the developer which passes through the area X2 and fed to the area X3 increases a speed and carried, and fed quickly into the carrying path 6 or 8. In such a way, since a variance of a place of the developer is reduced, a stable image can be obtained, a stable development can be executed by a small quantity of developer, 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 in which developer is circulated and conveyed through a plurality of conveyance paths formed behind a developing sleeve.

(Prior Art) Conventionally, as the developing device, a plurality of developer conveyance paths are formed behind a developing sleeve, and these conveyance paths are connected at the rear end and the front end, and developer is stored in each conveyance path. By conveying the developer from the back side to the front side and from the front side to the back side by the developer conveying means, the developer as a whole is conveyed in a circular manner, and during the conveyance process, some of the developer is transferred to the developing sleeve. A device is provided that is adapted to be applied to the surface of the

On the other hand, image forming apparatuses such as copying machines and printers are becoming increasingly smaller. A device that forms a multicolor image requires a low-volume, thin developing device.

For this reason, in conventional developing devices, a large-diameter packet roller is provided in the developer transport path behind and adjacent to the developing sleeve, and this is used to supply developer to the surface of the developing sleeve. Since the packet roller increases the bulk of the developing device, in recent years, small-diameter screws have been mainly used in place of the packet roller.

However, the packet roller is equipped with multiple packets on the outer periphery in addition to the feed blades that transport the developer in the axial direction, and the developer is scooped up with these and sprinkled onto the surface of the developing sleeve. While screws have excellent supply and recovery properties, they are inferior to packet rollers in these respects.

Therefore, in the conventional developing device using the packet roller, sufficient developer can be supplied to the developing sleeve regardless of the amount of developer contained in the conveyance path. In addition, in a developing device that peels off the developer that has passed through the developing area from the surface of the -H developing sleeve and replaces the developer on the developing sleeve, the developer that has been peeled off from the developing sleeve is transferred to the conveyance path in packets. The developer can be quickly collected, and thus the developer can be smoothly replaced on the developing sleeve.

On the other hand, screws have a low ability to supply developer to the developing sleeve, and if the screw diameter is made smaller, the ability to supply and collect developer will fluctuate significantly due to slight fluctuations in the amount of developer.
Further, even if the copying machine is slightly tilted, the ratio of variation in the developer level to the diameter of the screw is large, resulting in unstable image quality and problems such as white spots and the like.

For this reason, in a developing device using a screw, a certain amount or more of developer must always be contained in the developing device and this must be maintained stably, making control extremely complicated.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and will be described with reference to FIG. 1.2 showing one embodiment. At the back is a developer conveying means (21),
Developer transport paths (6) and (7) having (25) and (28)
), (8) in the developing device (1) in which the developer is supplied to the outer circumference of the developing sleeve (17) while being circulated and conveyed in the conveyance path, the conveyance paths (6) and (7) ,
Among (8'), the conveyance path (6) adjacent to the developing sleeve
In the area (x2) excluding both the rear and front ends of at least one of the developer conveyance means (25) and (28) accommodated in the conveyance paths (7) and (8) other than the above, In the developer conveyance capacity reducing section, in this embodiment, the pitch of the blades (27) provided on the conveyance means (25) is adjusted to
), (X 3) has a shorter part.

(Function) In the developing device (1), the developer in the transport path (6) is transported from the back side to the front side based on the rotation of the developer transport means (21), and the developer in the transport path (7) is Developer transport means (2
The developer in the conveying path (8) is conveyed from the rear side to the front side based on the rotation of the developer conveying means (28), and the developer is completely developed. The agent is circulated through the conveyance paths (6), (7), and (8) in the developing device (1), and is supplied to the surface of the developing sleeve (17) during the conveyance process.

Further, the developer transported to the transport path (7) located at the rear of the transport path (6) adjacent to the developing sleeve (17) passes through the region (Xυ) on the near side and reaches the region (XZ) [developer Since the blade pitch (δ2) there is narrower than the areas (XL) and (XS), the conveyance speed of the developer is significantly reduced and the developer is accumulated.

The amount of variation in the amount of developer stored inside the developing device (1) is almost absorbed as the amount of variation in the amount of developer accumulated in the area (X2), and as a result, the level of developer in other areas remains almost constant. do.

Furthermore, the developer that has passed through the area (X2) and is sent to the area (X,
Or sent to (8).

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

Fig. 1.2 shows a developing device (1) according to the present invention, and the developing tank (1) is composed of a casing (2) and a cover (3).
4) includes, from the front, a developing section (5) and first to third conveyance paths (
6), (7), and (8) are formed, and in particular, the third conveyance path (8) is widened toward the front side, and a toner supply path (9) is formed.

In addition, the first conveyance path (6) and the second conveyance path (7) are separated by a partition wall (
11), but there is a communication passageway (12) between the back side and the front side.
), (13), and the second conveyance path (7) and third conveyance path (8) are separated by a partition wall (14), but the communication paths (15), ( 16). In addition, in the communication passages (12) and (15), as shown in FIG.
15).

A developing sleeve (17) is arranged in the developing section (5), and a cover (
The tips of the height regulating members (18) attached to 3) are opposed to each other with a predetermined development gap.

Note that a magnet roll (19) including a plurality of magnets arranged circumferentially with magnetic poles extending in the axial direction is housed in a fixed state inside the developing sleeve (17), and in particular, a magnet roll (19) is fixedly housed in the developing sleeve (17). (6), a non-magnetic pole part (20) is formed with the same poles (S, S) adjacent to each other.

Further, in the first conveyance path (6), there are supply blades (21) in which blades (23) each having a defective part (24) formed by partially cutting out an elliptical plate are attached to the shaft (22) at equal intervals. It is a provision.

Further, a blade (27) is attached to the shaft (26) in the second conveyance path (7).
) is provided in a spiral manner, and the pitch of the blades (27) is (δ1) in the front region (X, ) and (δ1) in the rear region, as shown in FIG. region(
X,) (δ3), and the area located between these (X2)
and (δ,), and the relationship between each is δ, = δ, 〉
δ, Toshishita. That is, the pitch (δ
2) is made narrower than the pitches (δυ, (δ,)) of the regions (X1) and (X3) on both sides, thereby reducing the conveyance capacity there.

Furthermore, a support shaft (29) is arranged in the third conveyance path (8) and the supply path (9), and an elliptical blade ( 30) are attached at equal intervals to form a conveyor blade (28), and the supply path (
A replenishment vane (31) is constructed by attaching a vane (32) in a spiral shape to the part located at 9), and the transport vane (28) and the replenishment vane (31) are configured to rotate integrally. .

The developer conveying operation and the developing operation in the developing device having the above configuration will be explained.

First, the developer stored in the third transport path (8) is transported from the back side to the front side based on the rotation of the transport blade (28) in the direction of arrow (d). Further, the toner supplied from the supply position (10) to the supply path (9) is conveyed from the front side to the back side based on the rotation of the supply blade (31) in the direction of arrow (d), At the front end of the transport path (8
) is mixed into the developer conveyed from the back side.

In addition, in this way, the integrally formed conveyance blade (
28) and the replenishment blade (31) in the same direction, the transport path (8) and the replenishment path (9) can transport the developer in opposite directions, respectively, because the transport blade (28) Oval blade (3
This is because by shifting the position of the defective portion (31) in 0), the developer can be sent in opposite directions while rotating the support shaft (29) in one direction. That is, as shown in FIG.
) when rotating in the direction of the arrow, if the area (a) of the elliptical blade (41) is removed, the developer is conveyed in the direction of the arrow (β'), and if the area (β) is removed, The developer is transported in the direction of the arrow (β').

Next, the developer transported from the back side to the front side of the transport path (8) is mixed with the toner replenished from the replenishment path (9) at the front end, and then transported through the communication path (16). It is fed into the second conveyance path (7). Note that, at the same time, when the developer is carried into the second conveyance path (7) from the first conveyance path (6) via the communication passage (13), the developer sent into the second conveyance path (7) is transferred to the second conveyance path (7). is transported from the front side toward the back side based on the rotation of the transport blade (25).

However, the transport blade (
25), the near side and the far side areas (Xt).

The blade pitches (δ1) and (δ,) in (X,) are wider than the blade pitch (δ2) in the area (X) surrounded by these areas (XI) and (X3). According to the rotation of the blade (25), the areas (X I), (X
In 3), the developer is quickly transported in the direction of the arrow, but in region (X2) it is transported at a slower speed than in regions (x t) and (x 3).

As a result, developer is gradually accumulated in the area (X2),
the amount of developer flowing from the area (xl) to the area (x2);
At the time when the amount of developer flowing out from the area (X,) to the area (x,) is balanced, the level of the developer in other conveyance paths and the like becomes constant. At that time, the stable developer level varies slightly depending on the total amount of developer built into the developing device (1), but the amount of variation in the total amount of developer is approximately within the range (the amount of developer accumulated in Other areas (X+) absorbed by varying amounts of drug.

The developer level in (X,) and the transport path (6) remains approximately constant despite changes in the total developer amount.

Next, the developer that has passed through the area (X2) and is conveyed to the back side of the area (X, 8) and transported separately. Note that in the communication passages (12) and (15), as mentioned above, the bottom of the passage (12) is lower than that of the passage (15). The amount of developer transported is larger, and only the developer that is too large to be sent to the first transport path (6) is sent to the third transport path (8). That is, the third conveyance path (8) functions as a developer storage tank.

The developer sent into the third conveyance path (8) is conveyed from the back side to the front side based on the rotation of the conveyance blade (29).

The developer sent into the first conveyance path (6) is transported by the supply blade (
Based on the rotation in the direction of arrow (b) of 21), it is conveyed from the back side to the front side, and sent into the second conveyance path (7) via the communication path (13) at the front end.

Note that when the developer is transported through the first transport path (6),
As shown by the arrow (e) in FIG.
It is held on the outer periphery of the developing sleeve (17) based on the magnetic force of the developing sleeve (19).

The developer held on the outer periphery of the developing sleeve (17) is
It is transported in the direction of arrow (a) based on the rotation of the developing sleeve (17), and the amount of transport is regulated at the portion facing the height regulating member (18).

The height-regulated developer is applied to the development area (
Y), where it comes into contact with the surface of the photoreceptor drum (100), which is an electrostatic latent image carrier, and supplies toner to the electrostatic latent image formed there, thereby making it visible.

The developer that has passed through the development area (Y) is transferred to the development sleeve (17
) is conveyed to the part opposite to the first conveyance path (6), the same pole is detached from the surface of the developing sleeve (17) by the non-magnetic pole part (20) formed adjacent to it, and the bottom surface of the casing is removed. is conveyed in the direction of arrow (f) along the first conveyance path (6
) is taken into the developer being transported.

Note that the developer level in the first conveyance path (6) is high;
When the density of the developer there becomes high, there is no place for the developer that has passed through the development area (Y) and separated from the surface of the development sleeve (17) at the non-magnetic pole part (20) to escape, and the development sleeve (17) and Area between casing (2) (P2)
The developer is clogged with the developer, and the developer spills out from the area (Pl) between the tip of the casing (2) and the photoreceptor drum (100).

Also, if the developer level in the first conveyance path (6) is too low,
The developing sleeve (17) is placed on the upstream side of the height regulating member (18).
The amount of developer adsorbed to the surface of the printer is small, resulting in poor image quality due to thinner images and white spots.

However, in the developing device (1) according to the present invention, as described above, the amount of variation in the total amount of developer in the developing device (1) is absorbed by the area (X2) of the second conveyance path (7), and area (x2)
, (Xs) and the first transport path (6) are maintained almost constant, the developing sleeve (1
7) The amount of developer adsorbed to and conveyed to the development area (Y) is constant.

In addition, since the developer density in the first conveyance path (6) is approximately constant at a predetermined value, the developing sleeve (17)
) The developer released from the surface of the conveyor blade (21) quickly
Since the developer is taken into the area (P2), the developer does not clog the area (P2), and the developer does not leak out from the area (Pl).

Next, in the developing device (1), even if the copying machine or the like that accommodates the developing device is tilted toward the back or the front due to the tilt of the floor or the installation stand, the second conveyance path (7) caused by this tilts. Since the flow of the developer is obstructed by the area (x2), the amount of uneven developer level between the back and front sides is small, resulting in developer spilling on one side and insufficient developer on the other side. This does not result in poor image quality.

Hereinafter, as shown in FIG. 1, as a conveying blade (25),
Blade pitch (δ1) in region (x +), (X 3)
).

As shown in FIG. (7
), the blade pitch (δ2) in the area (X2) of the conveying blade (25) shown in Fig. 1 is set to be the same (1, 0 am) as the area (Xυ, (Xl)). The results of a study on the replaceability of the developer on the developing sleeve (17) and the change in development characteristics with respect to the inclination using a developing device (1') that employs the following are shown below.
In the conveyor blade (25), the blade (27) has an outer diameter of 1'1
It has a diameter of 8 mm and is attached at an angle of 30° to the support shaft (26).

First, in order to study the agitation and charging of the developer on the developing sleeve (17), after putting a predetermined amount of developer into the developer tank (4) and copying 2,000 A4 size originals, Of the developer that spilled from area (Y) in the form of powder smoke, the amount of developer that spilled into area (P,) shown in Figure 2 and the amount of developer that spilled and accumulated in area (P2) were measured. The results shown in Table 1 below were obtained.

Table-1 (Unit: 119) As shown in this table-■, the developing device (119) according to the present invention
), it can be seen that the amount of developer spilled into the region (P2) is halved, and the amount of developer spilled into the region (Pυ) is reduced to about one-third.

The reason for this is that the developing device (1) has better mixing and agitating performance of the replenished toner and the circulating developer in the region (X2) of the transport path (7) and the charging property of the toner. This can be said to be superior to device (1').

Next, as shown in Fig. 5.6, the developing devices (1), (1') containing a predetermined amount of developer and the copying machine (50) containing them are installed with the front side facing away from the back side. Elevated state (A)
And, on the contrary, the back side is higher than the front side (B
), and after copying 1.2 million sheets of A4-sized originals, observations were made regarding developer spillage, image quality, etc., and the results shown in Table 2 below were obtained.

Table-2 In the developing device (1) according to (A), there is almost no problem even if the developing device (1) is tilted to θ-3°, and when the developer amount is 500 g, developer spillage was confirmed in the state (A). It was just that.

On the other hand, in the developing device (B) shown in FIG.
= Problems occurred in most cases even when tilted by just 1°.

Therefore, in the developing device (1) according to the present invention, there is little local variation in developer caused by tilting the developing device (1), and a substantially constant amount of developer is dispersed from the back side to the front side. It is judged that the amount of developer will not increase or decrease.

In addition, in the embodiment described above, the conveyance blades (
In other words, in the above embodiment, the pitch of the blades (27) in the transport blade (25) is changed, but the pitch of the blade (27) in the transport blade (25) is provided only in the area (x2) in the transport blade (25). 25) instead of the third conveyance path (8
) may be configured such that the blade pitch of the conveying blades (28) is narrowed in the portions excluding both ends, or the blade pitch of the conveying blades (25), (2
8) may also be provided with a mechanism for reducing the conveying capacity.

Further, in the above embodiment, the blade pitch is narrowed over the entire region (X2), but the pitch may be narrowed only in a part of the region.

Furthermore, in the above embodiment, the conveyance of the developer is reduced by narrowing the blade pitch of the conveyance blades (25), but the present invention is not limited to this. It is also possible to provide a section.

(Effects of the Invention) As is clear from the above description, in the developing device according to the present invention, in a developing device having a configuration in which developer is circulated and conveyed through a plurality of conveyance paths formed behind the developing sleeve, the developing device is adjacent to the developing sleeve. A developer conveyance capacity reducing section is provided in an area excluding both rear and front ends of the developer conveying means accommodated in a conveyance path other than the conveyance path to reduce the amount of developer accommodated in the developing device, This is intended to reduce local variations in the developer on the developing sleeve that occur due to the inclination of the developing device.

Therefore, it is possible to obtain a stable image even if the developing device is tilted, and in order to meet the demand for miniaturization of image forming devices and developing devices, even if a screw is used as a transport blade, the developer existing in the developing sleeve can be is the longitudinal direction (axial direction)
It is possible to obtain a clear image with no white spots or the like.

In addition, if the blade pitch is narrowed to form a developer transport capacity reducing part as in the above embodiment, the agitation of the developer there will be improved, and the developer will be sufficiently charged to produce images without background fog. can be obtained.

Furthermore, since the level of the developer in the conveying path adjacent to the developing sleeve is approximately constant, stable development is possible with as little developer as possible, which facilitates miniaturization of the developing device.

[Brief explanation of the drawing]

1.2 is a cross-sectional view and a vertical cross-sectional view of the developing device according to the present invention, FIG. 3 is a partial perspective view of the conveying blade of the third conveying path, and FIG. 4 is a cross-sectional view of the conventional developing device. , 5 and 6 are side views showing the copying machine in a tilted state. 1.1'...Developing device, 2...Casing, 5
...Development section, 6,7. Death...Transportation route, 9...
・Supply route, 11.14...Partition wall, 12.
13.15.16... Communication passage, 17... Developing sleeve, 21... Supply blade, 25.28... Conveyance blade, δ8. δ2. δ, ...Blade pitch. Patent applicant: Minolta Camera Co., Ltd. Agent: Patent attorney: Aohaku Ao, and 2 others.
Figure 6

Claims (1)

[Claims] (1) A developing device in which a plurality of developer conveying paths having developer conveying means are provided behind the developing sleeve, and the developer is supplied onto the developing sleeve while being circulated and conveyed in the conveying path,
A developer conveyance capacity reducing portion is provided in an area excluding both ends of at least one developer conveying means accommodated in a conveyance path other than the conveyance path adjacent to the developing sleeve among the conveyance paths. Characteristic developing device.