JPH05134536A - Developing device - Google Patents

Abstract

PURPOSE:To provide the developing device which can form an adequate developer thin film without receiving the adverse influence by the electric field generating on the outside surface of a developing sleeve by a blade and smoothly transfers the developer to an image carrying member. CONSTITUTION:This developing device has the developing sleeve 2 which has an insulating characteristic and is disposed in the aperture of a housing 1 facing the image carrying member 20, a blade 4 which triboelectrifies the developer between the blade and the developing sleeve 2 and forms the developer thin film on the surface of the developing sleeve 2, a 1st electric field generating means which generates the electric field for attracting the developer to the outside surface of the developing sleeve 2 in a rotating angle range of the developing sleeve 2, i.e., the region for supplying the developer to the image carrying member 20 side, and a 2nd electric field generating means which generates the electric field for absorbing the developer in the rotating angle range corresponding to the neighborhood of the proximity position between the image carrying member 20 and the developing sleeve 2. The blade 4 is in contact with the position where the blade hardly receives the influence of the electric field from the electric field generating means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device such as a printer or a copying machine, and more particularly to a developing device using a non-magnetic one-component developer.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional developing device. The developing device includes a housing 1 having an opening facing the photoconductor drum 20. Non-magnetic 1 in the housing 1
A component type developer is contained. A developing sleeve 2 for supplying the developer to the photosensitive drum 20 is rotatably arranged in the opening of the housing 1.

In the housing 1, a fur brush roller 3 for pressing the developer against the developing sleeve 2 to supply the developer to the developing sleeve 2 and to charge the developer.
Are rotatably arranged. A blade 4 is provided near the opening of the housing 1 for frictionally charging the developer with the developing sleeve 2 and for forming a uniform developer thin film on the surface of the developing sleeve 2.

[0004]

In the conventional developing device,
In order to transfer the developer attached to the surface of the developing sleeve 2 to the photosensitive drum 20, a voltage having the same polarity as that of the developer is applied to the shaft portion of the developing sleeve 2.
The developer is supplied to the fur brush roller 3 depending on the action thereof. Therefore, there is a problem that the developer is not sufficiently supplied to the developing sleeve 2.

Therefore, the present applicant has developed a developing device in which the developer is smoothly supplied to the developing sleeve 2 and the developer is smoothly transferred from the developing sleeve 2 to the photosensitive drum 20, We have already applied (Japanese Patent Application No. 3-1453)
74).

FIG. 3 shows a developing device already developed by the applicant. In this developing device, inside the developing sleeve 2, a first fixed conductor 5 having a substantially semi-circular cross section, a second fixed conductor 6 having a substantially semi-circular cross section, and a first fixed conductor. An insulator 7 that electrically insulates the fifth fixed conductor 6 from the second fixed conductor 6 is arranged. The first fixed conductor 5, the second fixed conductor 6, and the insulator 7 are fixed to the housing 1, and the developing sleeve 2 is surrounded by a drive mechanism (not shown) in the direction of arrow B. Rotate to.

The first fixed conductor 5 extends along the inner peripheral surface of the developing sleeve 2 in the rotation angle range of the developing sleeve 2 which is a region for supplying the developer from the inside of the housing 1 to the photosensitive drum 20 side. Are provided. The second fixed conductor 6 is provided along the inner peripheral surface of the developing sleeve 2 in the rotation angle range of the developing sleeve 2 corresponding to the vicinity of the proximity position between the photosensitive drum 20 and the developing sleeve 2. The developer shall be negatively charged.

A voltage (+) having a polarity opposite to that of the developer is applied to the first fixed conductor 5 by a power source 11, and a voltage having the same polarity as the developer is applied to the second fixed conductor 6 by a power source 12. (-) Is applied. The negatively charged developer in the housing 1 is effectively adsorbed on the surface of the developing sleeve 2 by the electric field generated from the first fixed conductor 5 and evenly spread on the surface of the developing sleeve 2 by the blade 4. A developer thin film is formed and supplied up to the vicinity of the position where the photosensitive drum 20 and the developing sleeve 2 are close to each other. Then, the developer carried to the vicinity of the proximity position between the photoconductor drum 20 and the developing sleeve 2 is separated from the developing sleeve 2 by the electric field generated from the second fixed conductor 6, and is transferred to the surface of the photoconductor drum 20. Move.

In the developing device developed by the applicant of the present invention, the electric field from the first fixed conductor 5 and the second fixed conductor 6 inside develops depending on the contact position between the blade 4 and the developing sleeve 2. It was found to have an adverse effect on the formation of the agent thin film.

The present invention relates to the improvement of the developing device developed by the applicant of the present invention, and when forming a developer thin film on the surface of the developing sleeve with a blade, the adverse effect of the electric field generated on the outer surface of the developing sleeve is exerted. An object of the present invention is to provide a developing device in which a suitable developer thin film can be formed without receiving the developer, and the developer can be smoothly transferred from the developing sleeve to the image carrier.

[0011]

A developing device according to the present invention has a housing having an opening facing the image carrier and containing a developer therein, and an insulating member disposed in the opening of the housing. A blade for frictionally charging the developer between the developing sleeve and the developing sleeve and for forming a thin film of the developer on the surface of the developing sleeve; and for supplying the developer from the inside of the housing to the image carrier side. In the rotation angle range of the developing sleeve, which is a region of the above, the first electric field generating means for generating an electric field for adsorbing the developer on the outer surface of the developing sleeve, and the proximity of the image carrier and the developing sleeve. A second electric field for generating an electric field for separating the developer from the outer surface of the developing sleeve in the rotation angle range of the developing sleeve corresponding to the vicinity of the position. And a raw device, the blade is equal to or in contact with the receiving position hardly the influence of an electric field from the first field generating means and the second field generating means in the developing sleeve surface. The image bearing member includes a photosensitive drum, a photosensitive belt and the like.

The first electric field generating means is, for example, provided inside the developing sleeve in the rotation angle range of the developing sleeve which is a region for supplying the developer from the housing to the image carrier side. A first fixed conductor to which a voltage having a polarity opposite to that of the developer is applied is used.

As the second electric field generating means, for example, the first fixing is made inside the developing sleeve in the rotation angle range of the developing sleeve corresponding to the vicinity of the proximity of the image carrier and the developing sleeve. A second device which is provided separately from the conductor and to which a voltage having the same polarity as that of the developer is applied
Fixed conductor is used.

When the first fixed conductor is used as the first electric field generating means and the second fixed conductor is used as the second electric field generating means, the blade is the developing sleeve. The surface is brought into contact with a position corresponding to a separated portion between the first fixed conductor and the second fixed conductor.

[0015]

The electric field for adsorbing the developer to the outer surface of the developing sleeve is within the rotation angle range of the developing sleeve, which is a region for supplying the developer from the inside of the housing to the image carrier side by the first electric field generating means. Occurs.

Further, the second electric field generating means generates an electric field for separating the developer from the outer surface of the developing sleeve in the rotation angle range of the developing sleeve corresponding to the vicinity of the proximity of the image carrier and the developing sleeve. Occur.

Therefore, the developer is effectively adsorbed and supplied to the developing sleeve in the rotation angle range of the developing sleeve which is a region for supplying the developer from the inside of the housing to the image carrier side. Then, in the vicinity of the proximity position between the image carrier and the developing sleeve, the developer adhering to the developing sleeve is released from the developing sleeve and is transferred to the image carrier.

Since the blade is in contact with a position on the surface of the developing sleeve which is less susceptible to the electric field from the first electric field generating means and the second electric field generating means, the developing formed on the surface of the developing sleeve by the blade. The developer having a negative polarity and the developer having a positive polarity are mixed in the agent thin film without being separated. Therefore, the developer is easily transferred to the image carrier, and the developer is less likely to be scattered in the process of being carried to the vicinity of the proximity position between the developing sleeve and the image carrier photosensitive drum. Therefore, the developer can be smoothly transferred from the developing sleeve to the image carrier.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG.

The developing device comprises a housing 1 having an opening facing the photosensitive drum 20. Photoconductor drum 2
0 is rotationally driven in the direction of arrow A.

The housing 1 contains a non-magnetic one-component developer. The developer is assumed to be negatively charged. An insulating developing sleeve 2 for supplying a developer to the photosensitive drum 20 is rotatably arranged in the opening of the housing 1. As the material of the developing sleeve 2, urethane rubber, silicon rubber, synthetic resin or the like is used.

A blade 4 is provided near the opening of the housing 1 to frictionally charge the developer with the developing sleeve 2 and to form a uniform thin developer film on the surface of the developing sleeve 2. ing.

Inside the developing sleeve 2, a first fixed conductor 5 extending in the longitudinal direction of the developing sleeve 2 and having a substantially semi-circular cross section, and a longitudinal fixed portion of the developing sleeve 2 extending in the transverse direction. Second arc-shaped second fixed conductor 6 and developing sleeve 2
An insulator 7 that extends in the lengthwise direction and electrically insulates the first fixed conductor 5 and the second fixed conductor 6 from each other is arranged.

The first fixed conductor 5, the second fixed conductor 6 and the insulator 7 are fixed to the housing 1,
The developing sleeve 2 rotates around these in the direction of arrow B by a drive mechanism (not shown).

The insulator 7 has a circular cross section, and a pair of protrusions 8 and 9 are formed on the surface of the insulator 7 at positions 180 degrees apart from each other. One protrusion 8 is the housing 1
It is located above the upper end of the inner opening, and the other protrusion 9 is located in the lower part of the housing 1.

The first fixed conductor 5 is fitted into and fixed to the inner side of the housing 1 between the protrusions 8 and 9 of the insulator 7. That is, the first fixed conductor 5 extends along the inner peripheral surface of the developing sleeve 2 in the rotation angle range of the developing sleeve 2 which is a region for supplying the developer from the housing 1 to the photosensitive drum 20 side. It is provided.

The second fixed conductor 6 is fitted and fixed to the outer side of the housing 1 between the two protrusions 8 and 9 of the insulator 7. That is, the second fixed conductor 6 is provided along the inner peripheral surface of the developing sleeve 2 in the rotation angle range of the developing sleeve 2 corresponding to the vicinity of the proximity of the photosensitive drum 20 and the developing sleeve 2. ..

A voltage (+) having a polarity opposite to that of the developer is applied to the first fixed conductor 5 by the power source 11, and a voltage having the same polarity as the developer is applied to the second fixed conductor 6 by the power source 12. (-) Is applied.

When a voltage (+) having a polarity opposite to that of the developer is applied to the first fixed conductor 5, the electric field thereof corresponds to the first fixed conductor 5 on the outer peripheral surface of the developing sleeve 2. An electric field for adsorbing the developer is generated on the outer surface of the rotation angle range.

When a voltage (-) having the same polarity as that of the developer is applied to the second fixed conductor 6, the electric field thereof causes the outer surface of the rotation angle range corresponding to the second fixed conductor 6. An electric field is generated to separate the developer from the.

Therefore, the developer in the housing 1 is
The electric field generated from the first fixed conductor 5 effectively attracts the surface of the developing sleeve 2 and the blade 4 forms a uniform developer thin film on the surface of the developing sleeve 2, thereby developing the photosensitive drum 20 and the developing drum 2. It is supplied to the vicinity of the position close to the sleeve 2. Then, the developer carried to the vicinity of the proximity position between the photosensitive drum 20 and the developing sleeve 2 is
The electric field generated from the second fixed conductor 6 separates the developing sleeve 2 from the developing sleeve 2, and transfers the developing conductor to the surface of the photosensitive drum 20.

As shown in FIGS. 1 and 2, the blade 4 is arranged so as to come into contact with the surface of the developing sleeve 2 within the rotation angle range where the protrusion 8 of the insulator 7 is located. That is, the blade 4 is in contact with the surface of the developing sleeve 2 at a position where it is unlikely to be affected by the electric field from the first fixed conductor 5 and the second fixed conductor 6.

The developer is charged in the housing 1 by mutual friction and in the friction between the developing sleeve 2 and the blade 4. In this example, the polarity with which the developer is charged is negative in principle, but there is also a developer that is partially charged with positive polarity.

Assuming that the blade 4 is in contact with the surface of the developing sleeve 2 at a position corresponding to the first fixed conductor 5, the blade 4 is affected by the electric field from the first fixed conductor 5. The negative-polarity developer gathers inside the formed developer thin film, and the positive-polarity developer gathers outside. When the positive-polarity developer gathers in the outer portion of the developer thin film, the developing sleeve 2 and the photosensitive drum 20
In the vicinity of the position close to, the negative polarity developer inside the developer thin film is less likely to be transferred to the photosensitive drum 20.

If the blade 4 is in contact with the surface of the developing sleeve 2 at a position corresponding to the second fixed conductor 6, the blade 4 will be affected by the electric field from the second fixed conductor 6. The positive polarity developer gathers inside the formed developer thin film, and the negative polarity developer gathers outside. When the positive-polarity developer gathers inside the developer thin film, the negative-polarity developer is weakly attracted to the developing sleeve 2 and is carried to a position near the developing sleeve 2 and the photosensitive drum 20. In, the developer is easily scattered.

In this embodiment, the blade 4 is in contact with the surface of the developing sleeve 2 at a position where it is unlikely to be affected by the electric fields from the first fixed conductor 5 and the second fixed conductor 6, so that the blade 4 is in contact with the surface of the developing sleeve 2. Since the negative-polarity developer and the positive-polarity developer are mixed in the developer thin film formed by No. 4 without being separated, the developer is easily transferred to the photosensitive drum 20, and Is the developing sleeve 2
The developer is less likely to be scattered during the process of being carried to the vicinity of the position close to the photosensitive drum 20. Therefore, the developer can be smoothly transferred from the developing sleeve to the image carrier.

If the contact position between the blade 4 and the developing sleeve 2 is within the rotation angle range R where the protrusion 8 of the insulator 7 is located on the surface of the developing sleeve 2, the contact range between the blade 4 and the developing sleeve 2 (Nip width) can be set arbitrarily.

Although the fur brush roller is not provided in the above embodiment, the fur brush roller may be provided. The present invention can also be applied to a developing device in which a developer is positively charged. In that case, the first fixed conductor 5 and the second fixed conductor 6 are applied with a voltage having a polarity opposite to that of the above-described embodiment.

[0039]

According to the present invention, when a developer thin film is formed on the surface of the developing sleeve by the blade, a suitable developer thin film is formed without being adversely affected by the electric field generated on the outer surface of the developing sleeve. Thus, the developer can be formed and the developer can be smoothly transferred from the developing sleeve to the image carrier.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a developing device showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a developing device showing a conventional example.

FIG. 3 is a configuration diagram showing a developing device that the present applicant has already developed.

[Explanation of symbols]

 1 Housing 2 Developing Sleeve 4 Blade 5 First Fixed Conductor 6 Second Fixed Conductor 11 Power Supply 12 Power Supply

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masahiko Sakae 1-2-2 Tamatsukuri, Chuo-ku, Osaka City, Osaka Prefecture Mita Industry Co., Ltd. No. 28 within Mita Industry Co., Ltd.

Claims (2)

[Claims] 1. A housing having an opening facing the image carrier and containing a developer therein, an insulating developing sleeve arranged in the opening of the housing, and the developing sleeve. A blade for frictionally charging the developer and forming a developer thin film on the surface of the developing sleeve, and a rotation angle range of the developing sleeve which is a region for supplying the developer from the inside of the housing to the image carrier side. A first electric field generating means for generating an electric field for adsorbing a developer on the outer surface of the developing sleeve; and a rotation angle of the developing sleeve corresponding to the vicinity of the proximity of the image carrier and the developing sleeve. A second electric field generating means for generating an electric field for separating the developer from the outer surface of the developing sleeve, wherein the blade is the present one. Said the sleeve surface first
Of the electric field generating means and the second electric field generating means are in contact with a position that is less likely to be affected by the electric field. 2. The first electric field generating means is provided inside the developing sleeve in a rotation angle range of the developing sleeve which is a region for supplying the developer from the housing to the image carrier side. It is composed of a first fixed conductor to which a voltage having a polarity opposite to that of the developer is applied, and the second electric field generating means rotates the developing sleeve corresponding to a position near the image carrier and the developing sleeve. In the angular range, it comprises a second fixed conductor which is provided inside the developing sleeve separately from the first fixed conductor and to which a voltage having the same polarity as the developer is applied, and the blade is the surface of the developing sleeve. The first in
2. The developing device according to claim 1, wherein the fixed conductor and the second fixed conductor are in contact with each other at a position corresponding to the separated portion.