JPH05333691A - Developer circulation method for magnetic brush developing device - Google Patents

Abstract

PURPOSE:To cause developer in a magnetic brush developing device to smoothly circulate and to always form a stable magnetic brush having uniform toner concentration on a developer carrier. CONSTITUTION:Two augers 2 and 5 are arranged up and down so that their carrying directions are opposite to each other; the developer 9 is carried to circulate between a developer reservoir for stirring 6 and a developer reservoir for supplying 3 by the augers, and supplied to the developer carrier 7 provided with a fixed magnet adjacent to the auger 2 arranged in the developer reservoir for supplying, then it is peeled and moved to the auger 5 arranged in the developer reservoir for stirring in a developer circulating method for a magnetic brush developing device 1. In this method, the developer carrying ability(the amount of the developer carried per unit time) of the augers 2 and 5 is set higher than but lower than three times of that of the developer carrier 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer circulating method for a magnetic brush developing device used in an electrophotographic copying machine.

[0002]

2. Description of the Related Art A magnetic brush developing device used in an electrophotographic copying machine will be described with reference to the drawings. 1 is a cross-sectional view of the magnetic brush developing device, and FIG. 2 is a schematic front cross-sectional view taken along the line AA of FIG.

As shown in FIGS. 1 and 2, in a magnetic brush developing device 1 used in an electrophotographic copying machine, at least two main augers 2 and 5 of a plurality of augers are arranged vertically with a partition wall 4 interposed therebetween. However, each of them is configured to convey the developer 9 in opposite directions, and has a magnetic force in a predetermined distribution fixedly arranged adjacent to any one of the augers 2 so that its outer periphery rotates. Has a developer carrier 7 and supplies the developer 9 carried by the adjacent one auger 2 to the developer carrier 7, and the developer on the developer carrier develops the photoconductor 10. However, the remaining developer is configured to be returned to the other auger 5 described above. In such a magnetic brush developing apparatus 1, the developer 9 returned from the developer carrier 7 to the other auger 5 is circulated and conveyed to the one auger 2 described above, and is supplied to the developer carrier 7 again. Therefore, since the developer 9 is replaced with a new developer without remaining on the developer carrier, the toner concentration in the developer does not change, and a stable and uniform circulation of the developer is formed to form a uniform image. There was an advantage that can be obtained. (See Japanese Patent Publication No. 3-16026)

However, in the conventional magnetic brush developing device, the developer carrying capacity of the augers 2 and 5, that is, the ability to supply the developer to the supply side developer reservoir 3 is carried by the developer carrying member 7. Since the capacity, that is, the ability of the developer to be conveyed from the supply side developer reservoir to the stirring side developer reservoir via the agent carrier, is smaller than the supply side developer reservoir, Is supplied to the developer carrier more than the amount of the developer conveyed from the stirring side developer reservoir 6, and the remaining development is returned from the carrier 7 to the stirring side developer reservoir 6. Since the amount of the developer is larger than the amount of the developer conveyed and supplied to the supply side developer reservoir 3 by the lower auger 5, the developer 9 is deviated to the downstream side of the auger 5 in the stirring side developer reservoir 6. It is easy to accumulate and removes the residual developer as described above from the agent carrier. And by interfering with recirculating the toner density of the magnetic brush formed on the carrying member has occurred a problem that becomes uneven along the longitudinal direction.

Particularly in the case of a color copying machine, since a large area is often developed, the toner density of such a magnetic brush is likely to become non-uniform in the longitudinal direction, resulting in deterioration of image quality. It became a problem.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above problems and allows a developer in a magnetic brush developing device to be smoothly circulated, and a toner that is always stable on a developer carrier. An object is to provide a method for forming a magnetic brush having a uniform concentration.

[0007]

As shown in FIG. 1 and FIG. 2, the supply side developer reservoir 3 and the stirring side developer reservoir 6 are arranged one above the other by a partition wall 4, respectively, in opposite directions. In the magnetic brush developing device 1 having the upper auger 2 and the lower auger 5 that convey the developer 9, the developer 9 is agitated by the lower auger 5 and the developer pool 6 on the stirring side.
After being fed inside, it collides with the end portion 11 of the developer pool 6 on the stirring side, and is pushed up and replenished to the developer pool 3 on the supply side where the upper auger 2 is arranged as shown by an arrow d, and the upper auger 2 It is conveyed in the opposite direction to the lower auger 5. At this time, the developer 9 replenished in the supply-side developer reservoir 3 is carried by the trailing edge regulating member 8 supplied to the developer carrier 7 adjacent to the developer reservoir as shown by an arrow a. A magnetic brush regulated to have a predetermined spike is formed on the body, and the electrostatic latent image formed on the photoconductor 10 is visualized and developed. After that, the developer is peeled from the carrier as shown by the arrow b and returned to the developer pool 6 on the stirring side. The surplus developer 9 not supplied onto the developer carrier 7 naturally drops into the developer pool 6 on the stirring side at the position 12 on the opposite side to the above as shown by the arrow d, and the lower auger 6 It is returned to and recycled.

In such a magnetic brush developing device,
The developer carrying capacity (W ₁ g / sec) of the agent carrier 7 is regulated by the regulating member 8 (Ag / cm ² ), the radius of the agent carrier (rcm), the rotation speed (Rrps) and the agent. When the product W ₁ = A × 2πr × R × l of the carrier length ( ₁ cm) is represented, the amount of the developer pushed up by the lower auger 5 in the end 11 region of the developer pool 6 on the stirring side,
That is, the developer conveying capacity (Wdg / se
By setting the auger diameter, the auger rotation number, and the auger pitch so that c) becomes W ₁ <Wd ≦ 3W ₁ , a magnetic brush having a stable and uniform concentration is always formed on the developer carrier 7. To do.

[0009]

EXAMPLES The structure of the present invention will be described below based on examples. In the configuration of the present invention, in measuring the developer carrying capacity Wd, the developer carrier 7 is stopped and only the upper and lower augers 2 and 5 are rotated to stabilize the circulation of the developer 9 in the developing device 1. As shown in FIG. 3, the result of measuring the flow C of the developer supplied from the supply-side developer reservoir 3 to the stirring-side developer reservoir 6 as the developer transport capacity Wd is shown in FIG.
Shown in. The type I auger has a diameter of 23.5 mm and a pitch of 18 mm, and is a spirally wound metal plate. The type II auger has a pitch of 30 mm for the type I auger.
It is what It can be understood that the developer carrying capacity of the auger is proportional to the rotation speed of the auger. 30g /
The broken line indicated by sec indicates the developer carrying capacity W ₁ of the developer carrier 7.

Here, the developing device using each of the above-mentioned augers is equipped with a developer carrying capacity (W ₁ g / s) of the developer carrying member 7.
Under the condition that ec) is 30 g / sec,
The toner was consumed by continuously developing it uniformly over the entire length of the agent carrier 7, and the toner concentration of the developer 9 on the agent carrier 7 was measured by dividing it into three regions. At this time, the agent carrier is divided into three equal parts, and each developer 9 is supplied from the supply side developer reservoir 3 with the upper auger to the stirring side developer reservoir 6 with the lower auger 5.
Area 1, area 2, and area 3 are sequentially arranged from the side 12 that falls into the area. Also, measure the weight of the toner being developed,
Assuming that the toner in the developing device was uniformly consumed, the decrease in toner concentration was calculated and compared with each measured value.

(Example 1) Type I auger (18 mm
When the pitch) was rotated at a rotation speed of 227 rpm, the developer transporting capacity Wd of the auger was 26.5 g / sec. That is, the developer transporting capacity Wd of the auger of this embodiment is the developer transporting capacity W _{1 of the} agent carrier W = 30 g / s
It was ec or less.

(Embodiment 2) Type II auger (30 mm
The developer carrying capacity Wd of the auger when the pitch) is rotated at a rotation speed of 227 rpm is 44 g / sec and exceeds the developer carrying capacity W ₁ = 30 g / sec of the developer carrier 7.

(Embodiment 3) Type I auger (18 mm
Pitch), the rotation speed was 400 rpm, and the developer transporting capacity Wd of the auger was 42 g / sec. The developer transport capacity Wd of the auger of this embodiment exceeds the developer transport capacity W ₁ of the agent carrier.

(Example 4) Using a type II auger, the number of revolutions was increased to 500 rpm, and the developer in the developing device was observed with the developer conveying ability of the auger being extremely large. The developer transport capacity Wd of the auger at this time is 90
Developer carrying capacity W ₁ = 30 g of the agent carrier 7 in g / sec
It was more than 3 times / sec.

[0015]

The effects of each embodiment are as follows.

(Embodiment 1) As in Embodiment 1, the developer carrying capacity Wd of the auger is equal to the developer carrying capacity W _{1 of the} agent carrier.
When it is smaller than the above, the measurement result of the toner density at the time of toner consumption shows that the developing time becomes long in the regions 2 and 3 which are downstream of the lower auger 5 where the developer is likely to accumulate, that is, the continuous development, as shown in FIG. Then, as the toner is consumed, the toner concentration on the agent carrier is extremely reduced. From this, in the regions 2 and 3, on the downstream side of the stirring-side developer reservoir 6, the developed developer whose toner has been consumed by the accumulated developer is less likely to be peeled off from the developer carrier 7. It can be understood that the replacement of the developer on the agent carrier is not smoothly performed, and a part of the same developer is continuously accumulated on the agent carrier. This is the photoconductor 10.
Meaning that the density of the image developed above is not sufficient,
The inconvenience occurs that a uniform image cannot be obtained.

(Embodiment 2) As in Embodiment 2, when the developer carrying capacity Wd of the auger is sufficiently larger than the developer carrying capacity W ₁ of the developer carrier, the toner consumption test result is shown in FIG. As shown in the drawing, even if the toner is continuously consumed, the toner is uniformly consumed over time, a good toner concentration is exhibited in the entire area of the agent carrier 7, and the developer is smoothly circulated. It can be understood. According to this developing method, it is possible to obtain an image in which the density of the image developed on the photoreceptor is uniform over the longitudinal direction of the developer carrier.

(Embodiment 3) As in Embodiment 3, when the developer carrying capacity Wd of the auger is sufficiently larger than the developer carrying capacity W ₁ of the developer carrier, the same results as in Embodiment 2 are obtained. Was given.

(Embodiment 4) As shown in Embodiment 4,
When the developer carrying capacity Wd of the auger is significantly larger than the developer carrying capacity W ₁ of the developer carrier (Wd> 3W ₁ ), the developer 9 which has been pushed up and carried upstream of the upper auger 2 is first. It is observed that the developer is remarkably biased and accumulated in the region (region 3) supplied to the developer carrier 7, and the developer is packed at a high pressure in the upstream end portion 11 of the supply-side developer reservoir. In addition, the driving force of the developing device is increased. From this fact, considering the stress on the developer and the effects on the durability and reliability of the device such as pairing in the developing device, it is preferable that the auger has an extremely large developer transporting capacity (Wd). Absent. Excessive stress on the developer deteriorates the charging performance of the toner. Therefore, it is preferable that the driving force of the apparatus is small, and in this embodiment also, it is necessary to set the developer transporting capacity Wd of the auger to about 3 times or less the developer transporting capacity W ₁ of the agent carrier. As described above, according to the contents of the present invention, since the developer is constantly circulated smoothly, it is possible to form a stable and uniform magnetic brush on the agent carrier, and the electrophotographic apparatus according to the present invention. Then, a stable and uniform image quality is achieved.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic brush developing device.

2 is a schematic front sectional view showing the arrangement of an auger and the flow of developer in the magnetic brush developing device shown in FIG.

FIG. 3 is a developer transport capacity W with a predetermined auger configuration
The characteristic view which shows the measurement result of d.

FIG. 4 is a characteristic diagram showing changes in developing time and toner density on a developing roll.

FIG. 5 is a characteristic diagram showing changes in developing time and toner concentration on a developing roll.

[Sign code]

1. Magnetic brush developing device, 2. Upper auger, 3. Supply side developer reservoir, 4. Partition wall, 5. Lower auger, 6. Agitator side developer pool, 7. Developer carrier, 8. Regulating member, 9. Developer, 10. Photoreceptor, 11. 12. The downstream end of the agitating developer pool, 12. Downstream end of developer reservoir

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masanori Kato 2274 Hongo, Ebina, Ebina, Kanagawa Fuji Xerox Co., Ltd.Ebina business office (72) Shintaro Kaneko 2274, Hongo, Ebina, Kanagawa Fuji Xerox Co., Ltd. Ebina business (72) Inventor Yutaka Yakabe 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Works (72) Inventor Shinichi Kuramoto 2274 Hongo, Ebina City, Kanagawa Fuji Xerox Co., Ltd. Ebina Business Office (72) Invention Tatsuya Nitta 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (1)

[Claims] 1. Two augers are arranged one above the other so that the respective conveying directions are opposite to each other, and the developer is circulated and conveyed between the agitating developer reservoir and the supplying developer reservoir by the auger. , Is supplied to a developer carrier having a fixed magnet adjacent to one of the augers arranged in the supply developer reservoir, and then is peeled and moved to another auger disposed in the stirring developer reservoir. In the developer circulating method of the magnetic brush developing device configured as described above, the developer carrying capacity of the auger (the amount of developer carried per unit time) is higher than the developer carrying capacity of the developer carrier and is 3 times or less. And a method of circulating a developer in a magnetic brush developing device.