JPH05188775A - Developing device - Google Patents

Abstract

PURPOSE:To smooth reversely feed developer so as to flow, to keep the amount of the developer in a stirring part constant, to uniformize an electrostatically charged amount, and to obtain a stable image without the unevenness of density and the lowering of density by providing a driving means which makes a reversely feeding means for restoring the excess developer to a hopper part from the stirring part execute periodic motion. CONSTITUTION:By providing the driving means 31 which makes the developer reversely feeding means 1 execute the periodic motion, the developer smoothly circulates from the stirring part A to the hopper part B even in the case that the inclination of the means 1 is equal to or under an angle required for the natural drop of the developer. Namely, cylindrical projections 1-a are provided on both sides in the width direction of the leading edge of the member 1 on a developing sleeve 5 side. At such a time, the trailing edge projects to the hopper part B and is supported by the eccentric cam 31. The cam 31 is properly rotated by the driving source. Thus, the member 1 which abuts on the outer peripheral surface of the cam 31 rocks by following the rotation of the cam 31 with the projection 1-a of the leading edge as the center of rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus for forming an image by an electrophotographic method, in order to develop a latent image formed on a latent image carrier such as a photosensitive drum through a predetermined process,
A developing device as shown in FIG. 4 of the accompanying drawings was used. As seen in this conventional example, the developing device is mainly divided into a stirring section A and a hopper section B. The developer t is supplied from the hopper section B to the stirring section A, and the developer t
Was done by.

In this apparatus, the developer t is a one-component magnetic developer. A developing sleeve 5 as a developer carrying member is rotatably supported at both ends in the stirring section A and is connected to a driving member (not shown). The developing sleeve 5 is made of a non-magnetic material such as aluminum or stainless steel, and a magnet roller 6 having a plurality of magnetic poles is fixedly arranged in the internal space as a magnetic field generating member. The developing sleeve 5 is rotatable while being concentric with the non-rotating magnet roller 6. In the illustrated example, the magnet roller 6 has four magnetic poles 6a, 6b, 6c and 6d.
Reference numeral a designates a developing pole arranged at a position facing the photosensitive drum 30 which is a latent image carrier, and which includes the developing sleeve 5 and the photosensitive drum 3
The development is performed by applying the bias power supply E while it is zero. The magnetic pole 6b is a developer coating pole (cut pole) facing the blade member 7 that regulates the layer thickness of the developer t coated on the developing sleeve 5 so as to have a uniform predetermined thickness. Magnetic pole 6
Reference numerals c and 6d denote developer transporting electrodes, the positions of which are determined depending on the transporting state of the developer t in the stirring section A. The blade member 7 is attached to the blade base 8 and maintains a predetermined gap with the hanging developing sleeve 5. The blade member 7 may be a magnetic material or a non-magnetic material. A stirring rod 4 is arranged at a predetermined position of the stirring unit A as a stirring unit for stirring and transporting the developer t supplied from the hopper unit B to the vicinity of the developing sleeve 5. The stirring rod 4 is supported so as to be driven to rotate around the shaft portion 4a, and is opposite to the developing sleeve 5 that rotates in the arrow direction by a driving source (not shown) in the stirring portion A, that is, counterclockwise. The developer t is stirred by rotating in the clockwise direction. Further, the magnetic field formed by the fixed magnet roller 6 in the developing sleeve 5 behind the blade member 7 causes the developer t to circulate countercurrently, which also causes stirring. The developer t is imparted by stirring and rubbing so that a charge amount required to obtain a desired density is obtained.

On the other hand, at a predetermined position in the hopper portion B, the developer t accommodated therein is rotationally driven around the shaft portion 9a as a conveying means so as to sequentially move toward the stirring portion A. A crank-shaped carrier rod 9 supported by the carrier is disposed, and the carrier rod 9 is rotationally driven in the arrow (clockwise direction) by a drive system (not shown).

Further, a detecting means (not shown) for detecting the remaining amount of the developer t is arranged at a predetermined position in the hopper portion B, and the developer t in the hopper portion B is consumed for the development. When the need for replenishment arises, the replenishment display is turned on so as to replenish the developer t.

A supply port for supplying the developer t is provided on the upper part of the hopper B, and the supply port is provided with a lid 11 for preventing the developer t from scattering and a soft material such as a sponge. A seal member 10 made of an elastic member is provided.

A regulating member 2 for regulating the movement amount of the developer t is provided between the stirring section A and the hopper section B. The regulation member 2 has a substantially crank-like shape that overhangs the stirring portion A at the opening C through which the developer t passes.
This is because the developer t scraped up by the blade sheet 12 made of a soft elastic material attached to the tip of the conveying rod 9 of the hopper part B is forced to the stirring part A by the wedge effect at the curved opening part C. This is intended for the effect of being pushed in, and a constant amount always moves regardless of the remaining amount of the developer t stored in the hopper portion B. Also, the opening C
If the shielding member 3 made of a movable mylar sheet or the like covering the opening C is attached to the edge of the above, the backflow of the pushed developer t can be prevented, and thus the effect of more quantitative supply can be obtained.

The developer t supplied from the hopper B is developed by the stirring rod 4 as shown by p in the drawing.
After being conveyed to the vicinity, it is attracted to the developing sleeve 5 by the attraction force of the magnetic pole 6c (conveying pole) of the magnet roller 6 in the developing sleeve 5. Since the developing sleeve 5 rotates counterclockwise, the adsorbed developer t is conveyed in the same direction and swallowed by the developer pool D ₁ formed behind the blade member 7. The developer pool D ₁ is formed by being regulated by the magnetic pole 6b (cut pole) of the non-rotating magnet roller 6 and the blade member 7, and is a portion where electric charges are applied to the developer by rubbing. When the amount consumed in association with the amount is smaller than the amount supplied from the hopper B, the growth gradually increases. One end of the developer back-feeding member 1 is located behind the blade member 7, that is, in the developer reservoir D ₁ , and the other end is brought out into the hopper portion B and fixed to the inner wall of the hopper portion B. That is, as the developer pool D ₁ accumulates and grows the developer of the difference between the supply amount and the consumption amount, when the developer pool D ₁ reaches a predetermined amount or more, the developer flow D ₂
Occurs and is conveyed onto the developer back-feeding member 1, so that the developer pool D ₁ always keeps a constant amount, so that the charge amount of the developer t is also kept constant.

[0009]

However, in the above-mentioned conventional example, since the fluidity of the developer charged by rubbing with the developing sleeve and the blade member is remarkably lowered, a preferable reverse feeding state cannot be obtained, and the developer pool is not obtained. Has grown to a predetermined amount or more, and the circulating flow of the developer pool has been regulated, resulting in density unevenness and the like caused by charging failure.

As a means for solving this problem, a method in which the mounting angle of the reverse feeding member is made steeper than the own weight drop angle (anthropic angle) of the developer is conceivable, but from the constraint conditions of the constitution of other stirring means and the like. It is hard to say the preferred method.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to a developer carrier for carrying a developer for developing a latent image on a latent image carrier to the latent image carrier, and a developer carrier of the developer carrier. A stirring section having a stirring means for stirring the developer on the back, a hopper section having a conveying means for storing the developer and conveying the developer to the stirring section, the hopper section, and the stirring section A developing device having a regulating means located between the agitating means and a developer supplying means for supplying the developer to the stirring section according to the movement of the conveying means, and a reverse feeding means for feeding the developer from the stirring section to the hopper section. Even if the inclination of the reverse feeding means is equal to or less than the angle (anthropic angle) required for the natural drop of the developer, the smooth movement of the developer from the stirring section to the hopper section is provided by having the driving means for periodically moving the reverse feeding means. The amount of developer in the agitating section becomes possible because circulation is possible. It becomes possible to maintain a constant, it is always a stable image quality was set to be obtained.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 is a longitudinal sectional view of a developing device embodying the present invention, and FIG. 2 is a perspective view of the developing device from which some components are removed so that the internal structure can be seen. The description of the components described in the conventional example will be briefly described.

In FIG. 1, a transport rod 9 for transporting the developer t is arranged at a predetermined position of the hopper portion B. A blade sheet 12 is attached to the tip of the conveying rod 9 so that the developer t can be conveyed without staying in the hopper portion B. Between the stirring section A and the hopper section B, a plate-shaped regulating member 2 for regulating the movement of the developer t and keeping the supply amount to the stirring section A constant is provided. The regulation member 2 is provided with an opening C at a portion that is substantially crank-shaped and overhangs toward the stirring unit A side, so that the developer t scraped up by the blade sheet 12 provided at the tip of the transport rod 9 is removed. , This crank-shaped opening C
It can be forced into.

Therefore, the blade sheet 12 is the developing container 2
First, since it is necessary to follow the step on the surface of the regulating member 2, it is made of a soft elastic material such as urethane.
Thus, the supply amount can be kept constant regardless of the amount of the developer t in the hopper portion B. Also, the opening C
If the shielding member 3 such as a mylar sheet is attached to the sheet, the backflow of the pushed developer t can be prevented, and the effect of the above configuration is further enhanced.

The supply amount of the developer t from the hopper B to the agitator A is determined by the opening area of the opening C of the regulating member 2 and the conveying rod 9.
Depends on the rotation speed of. That is, the supply amount increases by increasing the opening area and increasing the rotation speed, and decreases by decreasing the opening area and decreasing the rotation speed.

In the present embodiment, the developer t supplied from the hopper B as described above is agitated by the agitating rod 4 which is arranged at a predetermined position in the agitator A and rotates in the clockwise direction. After being conveyed to the vicinity of the developing sleeve 5 as indicated by p, the magnet roller 6 in the developing sleeve 5 is conveyed.
Of the developing sleeve 5 by the attraction force of the magnetic pole 6c (conveying pole) of
Is adsorbed on. Since the developing sleeve 5 rotates counterclockwise, the adsorbed developer t is also conveyed in the same direction, and the developer pool D ₁ formed in the range D on the back surface of the blade member 7
Will be swallowed by. The developer pool D ₁ is formed by the magnetic force of the magnetic pole 6b (cut pole) of the non-rotating magnet roller 6 and the developer t being regulated by the blade member 7, and the developer is charged by the developing sleeve 5. This is the part that is given most by rubbing. Further, the developer pool D ₁ causes counterflow in the direction indicated by an arrow q in the figure as the developing sleeve 5 rotates.

As shown in FIG. 2, cylindrical protrusions 1-a are formed on the same center line as shown in FIG. 2 on both sides in the width direction of the tip of the developer reversing member 1 on the side of the developing sleeve 5. -A
Is slidably attached to the hole 21-a of the developing container 21. At this time, the rear end projects to the hopper B and is supported by the eccentric cam 31. The eccentric cam 31 is appropriately rotated by a drive source (not shown). As a result, the developer reversing member 1 in contact with the outer peripheral surface of the eccentric cam 31 is
It swings following the rotation of the eccentric cam 31 with the protrusion 1-a at the tip as the center of rotation. At this time, when the upper limit is located, the angle θ with respect to the horizontal position of the reverse feeding member is smaller than the angle (anthropic angle) required for the developer to naturally fall. Therefore, the developer reversing member 1 is provided with the eccentric cam 3
The developer t oscillated according to the movement of No. 1 and pushed in by the countercurrent in the q direction in the developer pool D ₁ moves smoothly even though the angle θ of the developer reversing member 1 is small. Then, after passing through the area D ₂ , it falls to the hopper B and is used again.

The developer used for the development forms a developer pool D ₁ at a portion below the developer reversing member 1, and the developer t
As the amount of the developer increases, the developer pool D ₁ grows, and when it reaches a predetermined amount or more, the developer pool D ₁ is conveyed onto the reverse feeding member 1. On the other hand, in order to always provide a stable image without density unevenness and density reduction, it is necessary to keep the amount of developer pool D ₁ constant and stabilize the amount of rubbing charge given by the rotation of the developing sleeve 5. ..

Therefore, the blade member 7 of the developer reverse feeding member 1
Since it is necessary to keep the tip position on the side constant, in the case of adopting such a swinging configuration, the center of swing is made to coincide with the tip position, and the tip position is irrespective of the movement of the developer back-feeding member 1. Must be kept constant and the amount of developer pool D ₁ must be kept constant.

However, since it is not preferable that the amount of the main developer pool D ₁ is changed depending on the amount consumed for image formation, it is necessary to control the supply amount conveyed from the hopper section B to the stirring section A. I won't.

That is, by setting the supply of the developer, which is larger than the consumption amount in the case of solid black or the like having the largest amount of image information, to the agitating section A, in combination with the conveyance on the developer reverse feeding member 1, It is possible to maintain a certain amount of developer pool D ₁ .

The supply amount can be set inexpensively and reliably by the size of the area of the opening C of the regulating member 2 and the number of rotations of the conveying rod 9 described above.

In the above, the eccentric cam 31 does not have to rotate continuously, may rotate at intervals, or may have an indefinite period. The eccentric cam 31 may be separated from the developer reversing member in the vicinity of the lift O of the eccentric cam 31 so that the rear end of the developer reversing member 1 collides with the tip of the lowering regulating member 2.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. Further, the description of the common members as in the first embodiment will be omitted. The present invention relates to the developer back-feeding member 1
It is characterized in that the stirring rod 4 of the stirring section A is used as the vibrating means of.

That is, the developer reversing member 1 is constructed so as to swing around the tip projection 1-a on the back side of the blade member 7, and the developer reversing member 1 until the stirring rod 4 reaches the top dead center.
Is pushed up, and when further rotated, it is returned to the lower limit position so that swinging is given, and the flow of the developer on the developer reversing member 1 forms an angle with the horizontal direction of the developer reversing member 1. Even if θ is small, the operation is performed smoothly, falls on the hopper B, and is used again.

It goes without saying that the other conditions are the same as those in the first embodiment.

In the embodiment, the developer back-feeding member is movable so that the eccentric cam or the stirring rod causes periodical movement such as rocking or vibration. However, the developer back-feeding member is fixed or elastically supported to perform the development. The agent reversing member may be vibrated by a vibrating means, for example, an eccentric cam or a stirring rod of the embodiment, or another vibrating device.

[0029]

As described above, according to the present invention, the developer is supplied from the hopper section to the stirring section by the conveying means, and the excess developer is returned from the stirring section to the hopper section by the chute-like reverse feeding means. The developing device is provided with a driving means for giving a periodic movement to the reverse feeding means, which allows the smooth reverse conveying flow of the developer regardless of the inclination angle of the reverse feeding means and further consumes the developer. It is possible to provide a low-priced developing device that keeps the amount of the developer in the stirring section constant regardless of the amount, makes the charge amount uniform, and provides a stable image without image loss, density unevenness, and density decrease.

In the case where the swinging center is provided at the tip end portion of the reverse feeding means located on the developer carrying member side, the developer pool at the back of the blade member for regulating the developer supply amount to the latent image carrying member is provided. The effect that the amount of developer is constant can be enhanced.

If the stirring means also serves as the driving means, the apparatus becomes simple.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a first embodiment implementing the present invention.

FIG. 2 is a perspective view of a first embodiment implementing the present invention.

FIG. 3 is a vertical sectional view of a second embodiment implementing the present invention.

FIG. 4 is a vertical sectional view of a conventional example.

[Explanation of symbols]

 1 developer back-feeding member 2 regulating member 4 stirring member 5 developing sleeve 9 stirring rod 31 eccentric cam A stirring unit B hopper unit

Claims (4)

[Claims] 1. A developer carrier that carries and conveys a developer for developing a latent image on the latent image carrier, and agitates the developer on the back side of the developer carrier. Located between the agitating section equipped with an agitating means and a conveying means for accommodating the developer and delivering the developer to the agitating section, the hopper section and the agitating section, and In a developing device having a restricting means for supplying the developer to the stirring section according to the movement of the conveying means and a back-feeding means for back-feeding the developer from the stirring section to the hopper section, periodic movement is performed on the back-feeding means. A developing device having drive means for giving the developing device. 2. The developing device according to claim 1, wherein the back-feeding unit has a swing center at a tip end portion located on the developer carrying member side and swings. 3. The developing device according to claim 1, wherein the driving unit also serves as the stirring unit in the stirring unit. 4. The developing device according to claim 1, wherein the developer is a one-component magnetic developer.