JP3161074B2 - Developing unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device having a stirring mechanism for uniformly stirring a two-component developer used in an electrostatic printing apparatus.

Generally, in an electrostatic printing apparatus, a two-component developer (hereinafter simply referred to as a developer) composed of a toner and a carrier for visualizing an electrostatic latent image formed on a photoreceptor or copy paper. ) Is widely used. The developing device requires a charging mechanism for the replenishment toner and a horizontal stirring mechanism for the developer to make the toner concentration distribution in the width direction uniform in the developing device. There is a demand for a function that can generate uniform heat efficiently with little heat generation.

[0003]

2. Description of the Related Art FIG. 4 is a schematic sectional view of a conventional developing device, and FIG.
Is a diagram for explaining the disadvantages of the conventional stirring mechanism,
This corresponds to a top view of both paddle screws in FIG.
FIG. 4 will be described below with reference to FIG. In order to make the description of the configuration and operation easy to understand, the same parts are denoted by the same reference numerals throughout the drawings, and the duplicate description thereof will be omitted.

In FIG. 4, 1 is a developing device, 2 is a developer,
Reference numeral 3 denotes a photosensitive drum. The main configuration of the developing device 1 includes a developing container 11, a hopper 12, a first paddle screw 13, a second paddle screw 14, a partition plate 15, an auxiliary paddle screw 1
6, consisting of a mag roller 17, a doctor blade 18, a scraper 19 with a guide mechanism, and the like. In FIG. 5, 15a and 15b
Denotes communication ports penetrating the partition plate 15, respectively.

[0005] A developing container 11 is disposed in proximity to the photosensitive drum 3 and maintains the developer 2 at a required concentration in the container.
A mechanism for supplying 2a to the photosensitive drum 3 is incorporated. The hopper 12 stores the toner 2a for replenishment, and controls the toner supply roller 12a so that the required amount of the toner 2a is
Supplied within 11.

[0006] The first paddle screw 13 and the second paddle screw 14 are screw shafts for feeding toner, or a plurality of independent blades, which are arranged in parallel in a developing device.
13a, 14a are spirally mounted screws, and a partition plate 15 is fixed to the bottom of the developing container 11 between the first and second paddle screws 13, 14 laid in parallel. A stirring mechanism is configured with both paddle screws. The developer 2 is provided in such a manner that the directions of transport of the developer 2 are opposite to each other with the partition plate 15 as a boundary.

The toner 2a replenished from the hopper 12 is stirred with the carrier (not shown) present in the developing container 11 while being conveyed in the direction toward the far end of the paper by rotating the first paddle screw 13 in the direction of arrow A. Partition plate 15 at transfer end
At the second paddle screw 14 side across the communication port 15b provided at the second position.

By rotating the second paddle screw 14 in the direction of arrow B, the developer 2 is stirred while being conveyed in the reverse direction, and the developer 2 is again transferred to the partition plate 15 on the near side of the paper as shown in FIG. The structure moves to the first paddle screw 13 side across the communication port 15a provided, and circulates the developer 2 while stirring it in an endless manner.

The auxiliary paddle screw 16 has a function of discharging the developer 2 to the second paddle screw 14 while rotating in the direction of arrow C. The auxiliary paddle screw 16 has passed over the upper part of the auxiliary paddle screw 16 in the direction opposite to the arrow C. Stir-mixed developer 2
Is magnetically attracted to the surface of the mag roller 17 rotating in the direction of the arrow D, and the mag roller is fixed to the cylindrical surface of the mag roller 17 by a doctor blade 18 fixed at a certain gap.
The extra developer 2 sucked on the surface of the cylinder 17 is scraped off,
A predetermined amount is conveyed in the direction of the opposing photosensitive drum 3.

As the mag roller 17 rotates in the direction of arrow D, the toner 2a attached to the cylindrical surface of the mag roller 17 in the form of a magnetic brush is electrostatically attracted to the latent image formed on the photosensitive drum 3. Form a visible image. The toner 2a that has not been sucked is peeled off by the scraper 19 with a guide mechanism and returned to the second paddle screw 14 side.

[0011]

The rotation speed of the conventional paddle screws 13, 14 is considerably high in order to increase the stirring efficiency. Thus, the uneven distribution and overflow of the developer 2 have been suppressed. However, when the screw pitch is set to a constant value, the developer 2 along both paddle screws 13 and 14 is removed.
Is almost constant.

However, in the case of the developer 2 having poor fluidity, the supplied toner is not mixed immediately due to the influence of the structure of the developing container 11 and may drift on the upper surface of the developer 2. The floating toner appears as raw toner on the mag roller 17 and causes the screen to be stained. Analysis of the problem that the toner was not mixed revealed the following.

In FIG. 5, the toner 2a supplied from the hopper 12 is transported in the direction of arrow E while being stirred and mixed with the carrier in the developing container by the rotation of the first paddle screw 13.

However, the toner 2a moving along the partition plate 15 does not get caught in the first paddle screw 13 and drifts from the point a to the point c via the point b as shown in the drawing. This is because an upwardly extending gap is formed between the vertical surface of the partition plate 15 and the outer peripheral edges of the paddle screws 13 and 14.

In order to improve the stirring ability, a method of increasing the rotation speed of both paddle screws 13 and 14 and a method of forming the gap small are considered. In either case, heat or stress is applied to the developer 2. This is not a good measure to alter the quality of the toner particles.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional disadvantages, and has as its object to provide a developer stirring function capable of improving the stirring ability without giving stress to the developer.

[0017]

In order to achieve the above object, as shown in FIG. 1, a first paddle screw 13 and a second paddle screw rotatably arranged in parallel in a developing device 1.
14 and between the paddle screws 13, 14 ,
Developer 2 by the partition plate 15 and having a communication port on the end portion
In the stirring mechanism for 攪拌a communication of the partition plate 15
At the position corresponding to the mouth, the first paddle screw 13 and
Along the outer edge of the second paddle screw 14
With a predetermined gap, and the communication port 15 of the partition plate 15
b and a part of the developer 2
And a regulating block 4 having an end face for obstructing the operation.

[0018]

[0019]

[Action] at the other side of the first paddle screw 13, regulatory Breakfast
The lock 4 is formed so as to protrude on both sides of the partition plate 15.
The partition plate as shown in FIGS. 2 and 3.
The conventionally widened gap between the vertical surface of 15 and the outer peripheral edges of both paddle screws 13 and 14 is eliminated.

As a result , the upper layer portion of the developer 2 conveyed by the first paddle screw 13 along the partition plate 15 is restricted.
The raised developer 2 blocked by the lock 4 flows in a direction away from the partition plate 15 and generates a turbulent flow, and the drifting toner 2a is caught in the turbulent flow to increase the diffusion effect. Can be. In addition, since there is no gap extending upward along the partition plate 15, drifting of the toner 2a drifting along the partition plate 15 on the first paddle screw 13 side can be prevented.

Similarly, on the second paddle screw 14 side , the regulating block 4 is formed so as to protrude on both sides of the partition plate 15, so that there is no gap extending upward along the vertical plane of the partition plate 15. The drift of the toner 2a can be prevented. Further, the restriction block 4 is disposed so as to close and narrow a part of the communication port 15b shown in FIG. As a result, when the developer 2 moves from the first paddle screw 13 to the second paddle screw 14, the developer 2 is blocked to increase the pressure of the developer 2, and when the developer 2 flows through the communication port, the developer 2 In this case, the flow rate is increased by generating a contraction flow associated with the jet flow, and acts to diffuse the developer 2 in the second paddle screw 14 having a low pressure, thereby increasing the stirring effect with the supplied toner 2a.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a top view of a main part arrangement of the developing device of the present invention, FIG. 2 is a sectional view taken along line GG 'of FIG. 1, and FIG. 3 is a cutaway perspective view of the main part showing the structure of the regulating block and the partition plate of the present invention. . FIG. 1 will be described below with reference to FIG. 2 and FIG.

FIG. 1 differs from FIG. 5 in that the outer periphery of the first paddle screw 13 and the second paddle screw 14 is provided at the end of the first paddle screw 13 opposite to the hopper 12, as shown in FIG. The point is that the restricting block 4 is provided so as to cover the upper part with a predetermined gap therebetween, and the communicating port 15b is narrowed to form the communicating port 15c as shown in FIG.

The regulating block 4 is formed by using a wear-resistant member, and is, for example, planted on a partition plate 15 or a developing container 11.
Fixed to. The predetermined gap is formed to be the same as the gap provided between the first paddle screw 13 and the developing container 11.

The upper layer portion of the developer 2 conveyed along the partition plate 15 in the direction of arrow E by the first paddle screw 13 is obstructed by the end face 4a of the regulating block 4 shown in FIG. The bulges along, and overflows in a direction away from the partition plate 15 to be in a turbulent state. As a result, the drift of the toner is eliminated, and the toner is caught by the first paddle screw 13 at a position along the wall surface of the developing container 11 due to the diffusion effect.

Although the conventional communication ports 15a and 15b are U-shaped cutout holes having no upper side, the communication ports shown in FIG. As shown in FIG. 15c, the hole is narrowed and has a rectangular shape having an upper side. As a result, when the developer 2 moves from the first paddle screw 13 to the second paddle screw 14, a contraction occurs due to the jet of the fluid at the communication port 15c, and the flow velocity increases to increase the stirring effect. Will increase.

That is, there is an effect that the stirring can be performed at a high speed without giving a stress to the developer 2. Developer 2
However, since the regulating block 4 is covered with a predetermined gap from the upper part of the outer peripheral edge of the second paddle screw 14 even when the second paddle screw 14 is moved to the second paddle screw 14, an upwardly widening gap as in the related art is formed. Therefore, drifting of the toner 2a is prevented.

Further, the time lag of the toner concentration control, which was about 10 seconds in the past, can be greatly reduced to about 0.5 seconds, which has the effect of being inexpensive and sufficiently practical. .

[0029]

As is apparent from the above description, according to the present invention, the generation of floating toner is eliminated, the diffusion efficiency is improved without applying stress to the toner, and the speed of toner density control is increased. There is.

[Brief description of the drawings]

FIG. 1 is a top view of a main part arrangement of a developing device of the present invention.

FIG. 2 is a sectional view taken along line GG ′ of FIG. 1;

FIG. 3 is a fragmentary perspective view showing the structure of the restriction block and the partition plate of the present invention.

FIG. 4 is a schematic cross-sectional view of a conventional developing device.

FIG. 5 is a view for explaining a drawback of a conventional stirring mechanism.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Developing device 2 Developer 2a Toner 13 1st paddle screw 14 2nd paddle screw 15 Partition plate 15a communication port 15c communication port

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-13981 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08

Claims (1)

(57) [Claims] 1. A provided between the first paddle screw and the second paddle screw and the two paddle screw rotatably parallel lateral bridging in the developing device, and by a partition plate having a communication port in the end, the developing agent in the stirring mechanism 攪拌, at a position corresponding to the communication port of the partition plate, wherein the first paddle
Along the outer edges of the first and second paddle screws.
Cover the upper part with a predetermined gap.
A part of the communication port of the plate is closed and narrowed, and the developer
A regulating block having an end face for preventing the progress of the developing device.