JPS63125963A - Developing device - Google Patents

Abstract

PURPOSE:To efficiently convey toner and carriers and to uniformly supply a developer onto a developing sleeve by fixing an end part of a blade in a developer conveying direction to a rotary shaft and allowing the opposite end part to move in a peripheral direction. CONSTITUTION:A 1st screw blade 3 and 2nd screw blade 4 are constituted of plural spiral members 32 and 42 respectively and fitted to conveyance paths 83 and 84 through rotary shafts 31 and 41 so that they can be driven by a casing 8, and the developer is mixed and agitated while conveyed as shown by arrows D and E according to rotations in directions shown by arrows (a) and (b). The downstream ends (e) of the blade members 32 and 42 in the developer conveying direction are fixed through fixing members 33 and 34 at 90 deg. to the rotary shafts 31 and 41. Parts except the downstream ends (e) are slidably in the peripheral direction while a fine gap (g) is left to the rotary shafts 31 and 41, and the free ends (f) is provided slidably to positions where they abut on the closest blade member. Consequently, the developer is not one-sided and a copy image never becomes uneven.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device used for developing electrostatic latent images in electrophotographic copying machines, microreader printers, and the like.

2. Description of the Related Art In general, a developing device conveys developer held on the outer peripheral surface of a developing sleeve in the circumferential direction, and transfers the developer held on the outer circumferential surface of a developing sleeve to the electrostatic latent image carrier in a developing area where the developing sleeve and the electrostatic latent image carrier face each other. The electrostatic latent image formed on the surface is developed.

In this case, the developer is supplied to the back side of the developing area of the developing sleeve, but at the time of this supply, the developer must be sufficiently mixed and stirred, and the toner must be sufficiently triboelectrically charged. There is.

Particularly in today's world where high-speed copying machines are required, the amount of toner consumed per unit time increases, so it is necessary to rapidly replenish toner and thoroughly mix and stir the developer in a short period of time. The amount of charge of the toner must be increased to a level suitable for development.

Furthermore, when toner is transported, it is necessary to uniformly supply the toner to the surface of the developing sleeve without causing any unevenness or accumulation of toner.

Therefore, in order to efficiently mix and stir the developer, a developer conveyance path is formed on the back side of the developing sleeve, and a screw roller having a spiral blade is provided as a conveyance means in the conveyance path. However, it has also been proposed that a roller is provided between the conveying path and the developing sleeve, and the toner and carrier are conveyed while being mixed and stirred using two rollers.

Problems to be Solved by the Invention However, in the proposed device, if too much toner is replenished, or if the conveying forces of the screw roller and the packet roller are unbalanced, the developer may shift or accumulate. There was a problem that unevenness occurred in the copied image.

An object of the present invention is to solve the above-mentioned problems and to efficiently transport toner and carrier, and a means for solving the problems. In a developing device in which developer conveying blades are arranged to circulate and convey the developer while mixing and agitating the developer, an end of the blade in the developer conveying direction is fixed to the rotating shaft, and an opposite end is fixed in the circumferential direction. It was made possible to move to.

Function: If the developer is to shift or accumulate at one point on the developer transport blade, the downstream end of the blade (the part of the blade located in the developer transport direction) is fixed; Since the other end is movable in the circumferential direction of the rotating shaft, the free end of the blade moves in the circumferential direction depending on the amount of developer at one point of the blade, and the amount of conveyance is constant. The distribution of the agent in the transport direction is made uniform. Therefore, the developer does not become uneven or accumulate.

Example An embodiment of the developing device according to the present invention will be described below.

In Fig. Φ, (1) shows a photosensitive drum, and (2) shows a developing device according to the present invention, and this developing device (2) generally includes a developing section (5) equipped with a developing sleeve (51). , the first screw blade (3), and the second screw blade (4)
and a packet roller (7) that can be rotated integrally with the roller, and these are housed in a space made up of a casing (8) and a cover (9).

The developing sleeve (51) is made of a non-magnetic conductive material (for example, aluminum) formed into a cylindrical shape, and has minute irregularities formed on its outer peripheral surface by sandblasting, and is rotatably driven in the direction of the arrow (C). 8) is supported by
A magnetic roller (52) is fixedly housed inside and faces the surface of the photosensitive drum (1) in the developing area (A).

! As shown in FIG.
The two are separated by a partition plate (81) rising from the bottom of the casing (8), and communicate with each other through openings (12) and (13) at both ends. 83) and (84) have a gentle slope, one downstream end ('K), and (N) the other upstream end ('K).
It is located higher than L) and (M).

Moreover, the conveyance path (84) is formed parallel to the developing sleeve (51).

In FIG. 3, on the left side of the conveyance path (83) is a toner replenishment unit (11) that replenishes toner from a toner replenishment tank (not shown).
) will be established.

? The first screw blade 0) and the second screw blade (4) are
As shown in FIGS. 3 and 4, a plurality of helical members (32) and (42) are fitted in each, and a rotating shaft (31),
It is rotatably attached to the casing (8) via (41) and conveys the developer in the directions of arrows (D) and (E) based on the rotation in the directions of arrows (a) and φ. Mix/stir. Further, the packet roller (7) is configured to supply developer to the surface of the developing sleeve (51).

The blade members (32) and (42) are integrally molded products made of resin, and for example, as shown in FIG.
, has a length of 15 times around the outer circumference of (41).

The downstream ends (e) of the blade members (32), (42) in the developer conveying direction are attached to the fixing members (33), (42) so that the angle with respect to the rotating shaft (31), (41) is 90°.
43) Fixed via t1''.

On the other hand, the parts other than the downstream end (e) are the rotating shaft (31),
(41) with a small gap (g) in between, and the free end (f) is provided so as to be slidable up to a position where it comes into contact with the maximum/neighboring blade member. ing.

FIG. 6 is a diagram showing a state in which the free end (f) is in contact with a neighboring blade.

Bucket roller (as shown in Fig. 4, it holds the second screw roller (4) inside, and has grooved blades on the outer periphery for supplying the developer onto the developing sleeve (51). A portion (71) is formed.

In addition, a height regulating plate (91) is attached to the cover (9) to face the developing sleeve (51), and the developing sleeve (51)
1) to adjust the amount of developer transported (Fig. Φ).

Next, the operation of this embodiment will be explained using FIGS. 1 and 2.

First, when the drive device (not shown) is driven, the developing sleeve (51) and the first screw are moved in the conveying path ( While being mixed and stirred with the developer in 83), it is conveyed in the direction of arrow 0, and is moved to the conveyance path (84) through the opening (12).

At this time, since the blades (32) of the first screen roller (3) are elastic and the downstream end (e) is fixed to the rotating shaft (31) by the fixing part (33), the toner is distributed evenly. They are transported, mixed and stirred (Figure 5).

Next, the developer is applied to the second screw roller (4) by the arrow (
b) Based on the rotation in the direction, the arrow (
E) While being conveyed in the direction, the adjacent packet roller (7
] The developer is supplied to the surface of the developing sleeve (51) by the grooved blade portion (71) of the second screw roller (
4) Transported by

When a developer is about to accumulate at the - point of the blade members (32) and (42), the downstream end (e) is fixed, while the free end (f) is connected to the rotating shaft (31). )
, (41), the blades (32) are movable in the circumferential direction.
) and (42), the free end (fl) of the blade moves in the circumferential direction, the amount of conveyance becomes a dog, and the distribution of the developer in the conveyance direction is made uniform. Therefore, there is no unevenness in the developer supplied to the surface of the developing sleeve (51) (FIG. 5).

The developer that has reached the downstream end (N) of the transport path (84) passes through the opening (13) and moves to the transport path (83).

In this way, the developer is transferred to the conveyance path (83) by the first screw roller G) and the second screw roller (4).

(84).

The developer held on the outer circumferential portion of the developing sleeve (51) is conveyed on the outer circumferential surface of the developing sleeve (51) in the arrow (E) direction based on the rotation of the developing sleeve (51) in the arrow (C) direction.
The developer cut into ears by the height regulating plate (91) develops an electrostatic latent image formed on the surface of the photoreceptor drum (1) in a development area (A) facing the photoreceptor drum (1).

Furthermore, new toner is replenished from the toner replenishing section (11) to the upstream side of the conveyance path (34)'p, and is conveyed along with the existing developer in the direction of arrow (D) within the conveyance path (83).
Mixed and stirred and sufficiently charged.

FIG. 7 is a graph showing the experimental results of the example related to this example, in which the amount of developer in the standard state is set to the standard value I.
By taking the relative value of the amount of developer on the screw roller as O and taking the pitch (P) between the blades of the screw roller as the vertical axis, we can calculate the amount of developer and the pitch (p ).

When the amount of developer is below the standard value of 1.0, the pitch (P) of the blades of the screw roller remains at 20 nods. When it exceeds the standard value of 1.0, the pitch becomes longer in proportion to the amount of developer.

However, when the amount of developer becomes twice the standard value of 1.0, the blade comes into contact with the adjacent blade, so even if the amount of developer increases beyond this, the pitch (P) increases to 40W or more. do not.

In addition, in the above embodiment, the blades (32), (42)
Although the fixing portions (33) and (43) are provided at one end, the fixing portion may be provided near the end, or at the end.

[Modified example]

Next, the blade members (32) and (4
2), as shown in Figure 8, the length of the rotating shaft (311).
The downstream end (h) of the blade (34) is fixed, and the parts other than the fixed end are connected to the rotating shaft (311), (4
11), and the downstream end (h) is the rotating shaft (311).

(411) by moving the circumferential surface of the blade (34).
The angle with respect to the axes (311) and (411) may be variable.

With this configuration, the length of the blades can be shorter than in the above method, and the blades can be easily molded integrally with the rotating shaft, thereby reducing manufacturing costs.

[Other Examples] On the other hand, the blades (36) are formed using a piece of metal such as aluminum, and the rotating shafts (312), (412) are connected by the support shaft (37).
), and one end is attached to a spring holder (3
8), and the other end may be provided with a helical spring (38) which urges in the direction of the arrow (X) by contacting the blade (36) (FIGS. 9 and 10).

With this structure, when the blade (36) comes to a part where developer is accumulated, the blade (36) resists the biasing force of the spiral splash (35) and removes the developer. The rotation axis (312), (412) of the blade (36) is proportional to the resistance force.
As the angle (θ) to the free end (36
a) moves in the direction of arrow (γ).

In addition, the support shaft (37) of the blade (36) is the rotation shaft (312),
It does not need to be fixed relative to (412) and may be movable within a predetermined range.

With this configuration, when there is a lot of developer at one point on the screw roller, the blade (36) is pushed by the resistance of the developer and moves against the urging force of the splash (35). and the rotation axis (312) of the blade (36).

The angle (θ) with respect to (412) becomes smaller, and the conveyance amount increases.

In addition, although the present invention was applied to both the first screw roller (3) and the second screw (4) on each side, uneven development occurs particularly when the developer is supplied to the developing sleeve (51). Since this is likely to occur, apply it only to the second screw roller (4) included in the packet roller (7), and apply it only to the second screw roller (4) included in the packet roller (7).
Even if a screw roller (3) having a conventional shape j) is used, uneven development can be reduced.

Effects of the Invention With the above-described configuration, the developing device according to the present invention changes the amount of conveyance proportionally to the increase or decrease of developer. The developer is not biased as a result of an unbalanced nut, and the copy image is not uneven.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the developing device, Figure 2 is xx' in Figure 1.
3 is a Y-Y' sectional view of FIG. 2, FIG. 4 is a z-z' sectional view of FIG. 2, and FIG. 5 is a sectional view of the first embodiment when there is less developer. A diagram showing the state of the blades of the screw roller, FIG. 6 is a diagram showing a modification of the current screw roller, FIG. 9 is a side view of the retaining part when metal blades are used, and FIG. 10 is the same. FIG. 31 , 41 , 311 , 312 , 411 , 41
2...Rotating shafts 32, 42, 34, 36...Spiral blades (developing, agent transporting blades) e...Downstream end (end in developer transport direction) f...Free end (opposite end) ) 37... Support shaft 35... Hanging spring (biasing means) Applicant: Minolta Camera Co., Ltd. Figure 2 Figure 3 Figure 5, E Figure 6 Figure 3 Figure 07ε Figure q

Claims (1)

[Scope of Claims] 1. In a developing device in which a plurality of developer transport blades are arranged on a rotating shaft and the developer is mixed and stirred while being circulated and transported, the ends of the blades in the developer transport direction is fixed to the rotating shaft, and the opposite end is movable in the circumferential direction. 2. The developing device according to claim 1, wherein the blade is made of an elastic member. 3. An end of the blade in the developer transport direction is provided to be swingable about a support shaft provided on the rotating shaft, and the blade is pivoted in the developer transport direction around the support shaft. The developing device according to claim 1, wherein the developing device is biased in a direction along the developing device.