JPH056098A - Two component developing device - Google Patents

Abstract

PURPOSE:To improve the fluidity of a developer on a developer stirring section, to stabilize the mixing of the developer and the chargeability of a toner by smoothing a stirring and to improve an image quality and the reliability of the device by restraining the scattering of the toner. CONSTITUTION:While restricting the carrying quantity of a developer X supplied from a developer supplying section 1 by a spear height restricting member 35, it is held on developing sleeves 33a and 33b which rotate around magnetic rollers 32a and 32b and carried to a developing area. A developer X1 whose carriage is stopped at the spear height restricting member 35 is accepted to a developer stirring section 4 and it is mixed and stirred with a toner supplied here and returned to a developer stirring section 1. Thus, the two component developing device A is constituded and the casing member 41 of the developer stirring section 4 is constituted of a magnetic material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art As a typical developing device in this type of image forming apparatus, a one-component developing device using a one-component developer mainly containing a developing toner and a two-component developing device mainly containing a toner and a carrier. There is a two-component developing device that uses a developer. Of these, the two-component developing device normally holds a developer supplied from a developer supply unit on a developing sleeve that rotates around a magnet body while controlling the amount of conveyance by a developer regulating member, and a photosensitive drum. And the like, and the electrostatic latent image on the latent image carrier is developed and visualized.

In such a two-component developing device, toner is consumed during development, and the toner concentration of the developer in the device is lowered. Therefore, a means for replenishing new toner is usually provided. The toner replenished from the toner replenishing means is mixed and stirred with the existing developer in the apparatus, charged by friction with the carrier, and then provided for development. This mixing and stirring is performed in various modes depending on the structure of the apparatus.
A developer stirring portion for receiving the developer whose conveyance is blocked by the developer regulating member is provided, and new toner is replenished to the stirring portion. Then, the mixture is agitated with new toner and returned to the developer supply section.

[0004]

However, in this type of developing device, the casing member of the developer stirring section is made of a non-magnetic material such as a synthetic resin for the purpose of facilitating the manufacture and suppressing the manufacturing cost. It is manufactured, and the developer regulating member generally faces the developing sleeve. Therefore, the developer stirring section is close to the developing sleeve so as to receive the developer from the regulating member, in other words, Since it is arranged close to the magnet body in the sleeve, the space inside the casing member of the stirring section is affected by the magnetic force of the magnet body.

That is, as a result of the developer in the stirring section being constrained by the inner wall of the stirring section casing member due to the influence of the magnetic field of the magnet body, the fluidity is poor, even when a ferrite-based carrier having good fluidity is adopted. In the case of a binder type carrier, it becomes an agglomerated state and the fluidity is extremely lowered. Therefore, there is a problem that the free movement of the developer in the developer stirring section is blocked, and the mixing and stirring with the new toner is not sufficiently performed. Even when the new toner is not replenished, the stirring of the developer expected in this stirring section becomes insufficient. If the stirring or the mixing and stirring becomes insufficient in this way, the chargeability of the toner becomes unstable, and it becomes difficult to provide a stable developer, which causes deterioration of image quality. Further, when toner charging failure occurs, toner is scattered to the surroundings in addition to development failure (image quality failure) such as background fogging.

Therefore, according to the present invention, the developer supplied from the developer supply section is held on the rotating developing sleeve around the magnet body while being controlled by the developer regulating member and conveyed to the developing area. On the other hand, in the two-component developing device in which the developer whose conveyance is blocked by the regulating member is received in the developer agitating section, mixed and agitated with the toner supplied thereto, and returned to the developer supplying section, Improves the fluidity of the developer in the agent agitator, thereby facilitating the mixing and agitation of the developer, stabilizing the chargeability of the toner, improving the image quality, suppressing toner scattering, and improving the reliability of the device. The purpose is to improve.

[0007]

According to the above-mentioned object, the present invention is provided on a developing sleeve which rotates around a magnet body while controlling the conveyance amount of a developer supplied from a developer supplying section by a developer restricting member. While being held and conveyed to the developing area, the developer whose conveyance has been blocked by the regulating member is received in the developer stirring section, mixed with the toner supplied thereto and stirred, and returned to the developer supplying section. In a two-component developing device, a casing member of the developer stirring section is made of a magnetic material, and a two-component developing device is provided.

Examples of the magnetic material of the casing member forming the stirring section include iron, nickel, and alloys such as stainless steel containing these.

[0009]

According to the developing device of the present invention, the developer supplied from the developer supply portion to the developing sleeve is held on the sleeve by the magnetic force of the magnet body inside the sleeve, and the developer is rotated as the sleeve rotates. The transport amount is regulated by the regulation member while being transported to the developing area, where it is used for developing the electrostatic latent image on the electrostatic latent image carrier. The remaining developer is returned to the developer supply unit again as the sleeve rotates.

On the other hand, the developer whose conveyance has been blocked by the developer regulating member is collected in the developer agitating section, and is agitated there, or after being agitated with new toner supplied thereto, and is again developed. It is returned to the agent supply section. Since the casing member of the stirring unit is made of a magnetic material, the magnetic force of the magnet body does not reach or hardly reaches the space inside the casing member. Therefore, the developer collected in the stirring unit is magnet body. Are mixed and stirred in a state of good fluidity without being affected by the magnetic force of.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a developing device of one embodiment, and FIG. 2 is an enlarged sectional view of a part thereof. The developing device A includes a developer supplying section 1, a toner concentration detecting section 2, a developing section 3, a developer stirring section 4, and a toner replenishing section 5.

The developer supply unit 1 is equipped with a bucket roller 12, which is shown in the drawing as only one of the left and right side plates 13 and the buckets installed in parallel with each other at a predetermined interval between the side plates. 14 and the transverse feed blade 15 arranged inside the bucket 14. This bucket roller is rotationally driven in the clockwise direction in the drawing by a driving means (not shown), scoops the two-component developer X containing toner and carrier by the bucket 14 and supplies it to the developing section 3, while the developer which has flowed into this roller is supplied. Is moved toward the left and right ends of the roller by the lateral feed blade 15.

The toner concentration detecting section 2 is provided with a developer conveying screw 21, which can convey the developer from the left and right end portions to the central portion, and passes through the central portion. An ATDC sensor 22 for detecting the toner concentration of the developer is provided. The developing unit 3 includes an upper developing unit 31a and a lower developing unit 31b below the upper developing unit 31a. The upper developing unit 31a includes a fixed magnet roll 32a and a developing sleeve 33a that rotates around the fixed magnet roll 32a, and the lower developing unit 31b includes a fixed magnet roll 32b and a developing sleeve 33b that rotates around the fixed magnet roll 32b. These developing sleeves 33a and 33b are rotationally driven in the clockwise direction in the drawing by a driving means (not shown).

Note that the upper developing sleeve 33a faces the spike height regulating member 35 which is a developer regulating member. The developer stirring section 4 is provided above the bucket roller 12 and at a position where the developer is collected from the spike height regulating member 35, and includes a casing member 41 and a stirring roller 45 housed in the casing member 41. The casing member 41 is entirely made of an iron material which is a magnetic material, one end portion 42 thereof faces the spike height regulating member 35, and the opposite end portion 43 thereof faces the bucket roller 12. The stirring roller 45 is provided with a stirring blade 44, and is rotationally driven in the clockwise direction in the drawing by a driving unit (not shown).

The end portion 43 of the casing member 41 faces the outermost movement locus circle C of the bucket 14 of the bucket roller 12 with a predetermined gap G. Toner supply section 5
Is a toner storage chamber 53 arranged above the stirring roller 45.
And a toner replenishing chamber 51 provided beside it, a brush roller 54 is provided in the toner reservoir chamber 53, and a toner conveying member 52 is provided in the toner replenishing chamber 51.
A toner replenishing port 55 is formed between the toner reservoir chamber 53 and the developer agitating section 4, and a perforated plate 56 such as a wire mesh is arranged at the replenishment port, and the brush roller 54 is the perforated plate. While being in contact with 56, they are rotationally driven in the clockwise direction in the drawing by a driving means (not shown). The toner conveying member 52 is rotationally driven in the counterclockwise direction in the drawing by a driving unit (not shown).

The developing device described above is incorporated in a copying machine so that the developing sleeves 33a and 33b of the developing section face the photosensitive drum B with a predetermined developing gap. According to this developing device, the developer X is supplied to the lower developing sleeve 33b in the developing unit 3 by the rotation of the bucket roller 12 in the developer supplying unit 1, and the developer thus supplied has the magnetic force of the magnet roll 32b. Based on the above, it is held on the sleeve, conveyed as the sleeve rotates, and comes to a position facing the upper developing sleeve 33a. Here, based on the magnetic forces of the lower magnet roll 32b and the upper magnet roll 32a, it moves onto the upper developing sleeve 33a and reaches the spike height regulating member 35 with the rotation of the sleeve, where the conveyance amount is regulated, The developer that has passed through the member 35 reaches the first developing area 34a as the upper sleeve 33a rotates, and develops the electrostatic latent image on the photosensitive drum B here. The developer that has passed through the developing area 34a is transferred to the upper sleeve 33.
a on the lower sleeve 33b, and the sleeve 33
The second developing region 34b is reached with the rotation of b, and the electrostatic latent image is surely developed there again, and the excess developer is conveyed to the developer supply unit side with the rotation of the sleeve. At the separation magnetic pole N5 of the magnet roll 32b, it separates from the sleeve 33b and flows into the developer supply unit 1.

On the other hand, a part of the developer X which is moved by the rotation of the bucket roller 12 is supplied to both ends of the screw 21 in the toner concentration detecting section 2 and is moved from here to the center thereof as the screw 21 rotates. Then, after the toner concentration is detected by the toner concentration detection sensor 22, the toner flows again into the developer supply unit 1. The developer X _{1 which} has been prevented from being conveyed by the spike height regulating member 35 flows into the casing member 41 from the end portion 42 of the casing member 41 of the developer stirring unit 4 and is collected therein, and is agitated by rotation of a stirring roller 45 in the member. Then, the casing member end portion 43 side is returned to the developer supply unit 1 again.

The toner replenishing section 5 is a toner concentration detecting sensor 2
The operation is performed so as to replenish the required amount of toner according to the toner density detected by 2. When the toner replenishing unit 5 replenishes the new toner, the toner supplied to the toner reservoir chamber 53 by the rotation of the toner conveying member 52 in the toner replenishing chamber 51 is replenished by the rotation of the brush roller 54 in the chamber 43 and the toner replenishing chamber 53. It is supplied into the developer stirring section 4 through the port 55.

The new toner supplied to the developer stirring section flows into the developer X ₁ by the rotation of the stirring roller 45.
Is mixed and stirred, and is supplied to the developer supply unit 1. Since the casing member 41 in the developer stirring section is made of a magnetic material, as shown in FIG. 2, the magnetic forces of the upper and lower magnet rolls 32a and 32b in the developing section 3 are the magnetic force of this member 41.
Therefore, the developer X ₁ collected in the stirring section 4 after being prevented from being conveyed by the spike height regulating member 35 is stirred with good fluidity without being affected by the magnetic force. When the new toner is replenished from the toner replenishing section 5, the toner is sufficiently mixed and agitated, so that the chargeability of the toner is stabilized and the developer is supplied after the expected toner charge amount is obtained. And then supplied for development. As a result, the quality of the image obtained in the copying machine is improved, the toner scattering is suppressed, and the reliability of the entire apparatus is improved.

Further, the casing member end 43 of the stirring section 4
Is placed in a magnetic field by the magnet rolls 32a and 32b and magnetized, so that the magnetic brush 4 of the developer is attached to the tip of this magnet roll.
6 is formed, and the bucket roller 12 is formed by this magnetic brush.
There is also an advantage that the amount of the developer supplied to the developing unit 3 is regulated to a predetermined amount by the bucket 14. In other words,
The gap G between the member end portion 43 and the outermost peripheral movement locus circle C of the bucket roller 12 is set to a gap in which the amount of developer supplied to the developing unit 3 by the bucket 14 can be regulated by the magnetic brush formed here. ..

In order to enhance the effect of such a magnetic brush, as shown in FIG. 3, a magnet sheet MS or the like may be separately attached to the end portion of the casing member, and the magnetic brush thus formed may be used. ..

[0022]

According to the present invention, the developer supplied from the developer supply unit is held on the developing sleeve rotating around the magnet body while controlling the conveying amount by the developer restricting member to reach the developing area. In the two-component developing device configured to receive the developer whose conveyance is blocked by the regulating member into the developer agitating section while being conveyed, and mix and agitate the toner replenished therein, and to return the mixture to the developer supplying section, Improving the fluidity of the developer in the developer stirring section, thereby mixing the developer,
The stirring can be smoothed, the chargeability of the toner can be stabilized, the image quality can be improved, the toner scattering can be suppressed, and the reliability of the apparatus can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of the developing device shown in FIG.

FIG. 3 is a partial enlarged cross-sectional view of another embodiment of the present invention.

[Explanation of symbols]

 1 Developer Supply Section 12 Bucket Roller 3 Development Section 32a, 32b Magnet Roll 33a, 33b Development Sleeve 35 Ear Height Controlling Member 4 Developer Stirring Section 41 Casing Member 42, 43 End of Member 45 45 Stir Roller 46 Magnetic Ear 5 Toner Replenishment Part A developing device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Matsuura 2-3-13 Azuchi-cho, Chuo-ku, Osaka Within Osaka Kokusai Building Minolta Camera Co., Ltd. (72) Inventor Susumu Mikawa 2-chome, Azuchi-cho, Chuo-ku, Osaka No. 13 Osaka International Building Minolta Camera Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. A developing area in which a developer supplied from a developer supplying section is held on a developing sleeve that rotates around a magnet body while a conveyance amount is regulated by a developer regulating member. In the two-component developing device, the developer, which has been conveyed by the regulating member, is received in the developer stirring section, mixed and stirred with the toner replenished there, and returned to the developer supplying section. A two-component developing device, wherein the casing member of the developer stirring section is made of a magnetic material.