JP2002365913A - Development machine, process cartridge, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a development machine that easily controls dimensions by a simple structure and obtains high quality images, a process cartridge using the developing device, and an imaging device. SOLUTION: In the development machine that supplies developer by means of a development sleeve 3 incorporating a magnet 4, strike members 5 and 6 are disposed between the magnet 4 and the development sleeve 3. The magnet 4 is pressed, so as to strike the development sleeve 3 via the strike members 5 and 6.

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 a printer, a copying machine, a facsimile, and the like, a process cartridge using the developing device, and an image forming apparatus.

[0002]

2. Description of the Related Art As a developing structure of an electrophotographic image forming apparatus, a photosensitive drum and a non-magnetic developing sleeve are respectively held in separate frames rotatably supported around one rotation axis. A configuration using a process cartridge in which a photosensitive drum and a developing sleeve are opposed to each other and are pressed in a direction in which they are approached is known.

In a developing device of such a process cartridge, a magnet is arranged inside a developing sleeve, and attracts toner in a developing chamber to the developing sleeve by its magnetic force, and develops a latent image on a photosensitive drum. In this case, the magnetic force prevents the toner from moving from the developing sleeve to the photosensitive drum by the voltage applied between the photosensitive drum and the developing sleeve.

The magnetic force of the magnet at the developing position (in a narrow sense, a gap where the distance between the photosensitive drum and the developing sleeve is minimum, in a broad sense, near the gap) changes depending on the distance between the magnet and the developing position. When the distance changes, the change appears in the density on the image. Therefore, usually, the accuracy and configuration of individual parts are determined so that the change in the distance becomes small.

Conventionally, the magnet is fixed and held by another member different from the frame for fixing and holding the bearing portion of the developing sleeve, and the dimensions of the positioning portion between them are accurately maintained.

[0006]

However, in the above-mentioned prior art, the components involved in determining the magnetic force at the developing position include a bearing of the developing sleeve, a frame body for fixing and supporting the bearing, between the developing sleeve and the magnet. A frame coupled to the frame and supporting the magnet, and three.
Therefore, the configuration is complicated, and strict dimensional control is required for each part, and its manufacture is not always easy.

The present invention has been made to solve the above problems, and
An object of the present invention is to provide a developing device capable of easily performing dimensional management with a simple configuration and obtaining a high-quality image, a process cartridge using the developing device, and an image forming apparatus.

[0008]

A typical configuration according to the present invention for achieving the above object is a developing device for supplying a developer by a developing sleeve having a built-in magnet. A striking member is interposed therebetween, and the magnet is biased so as to strike the developing sleeve via the striking member.

In the above configuration, the gap between the magnet and the developing sleeve is ensured with high precision by the abutting member, so that the fluctuation of the magnetic force at the developing position can be suppressed small, and a high-quality image can be obtained. Become like

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIGS. FIG. 1 is an explanatory cross-sectional view showing a configuration of a photosensitive drum and a developing device in a longitudinal direction, FIG. 2 is an explanatory side sectional view M of the photoconductive drum and a developing device, and FIG. 3 is an image forming apparatus equipped with a process cartridge. It is a schematic explanatory view.

(Overall Configuration) First, an outline of the configuration of the process cartridge will be described with reference to FIG. The process cartridge 20 includes a photosensitive drum 1 and a charging roller
21 and the cleaning means 22 are attached, and the other second
A developing device 23 is attached to the frame 15, and both frames 14 and 15 are
It is configured to be rotatably connected by the

When the process cartridge 20 is mounted on the main body of the image forming apparatus and image formation is started, the surface of the photosensitive drum 1 is uniformly charged by the charging roller 21 and is exposed by an exposure means (not shown) according to an image signal. Is performed, a latent image is formed, and the latent image is developed into a visible image by developing with a developing device 23.

A recording sheet is conveyed from a cassette (not shown) by a pickup roller and a conveying roller pair 30 so as to synchronize with the image formation.
When a transfer bias is applied when the toner image is conveyed between the transfer roller 31 and the transfer roller 31, the toner image formed on the photosensitive drum 1 is transferred to a recording sheet, and is directly heated and fixed by a fixing unit 32 and discharged out of the apparatus.

On the other hand, the toner remaining on the photosensitive drum 1 after the transfer of the toner image is removed by the cleaning means 22.

As shown in FIG. 3, the photosensitive drum 1 and the developing roller 2 constituting the developing device are supported by frames 14 and 15 which are rotatably connected by a shaft 16. The photosensitive drum 1 and the developing roller 2 are urged by the pressure in a direction in which the photosensitive drum 1 and the developing roller 2 come into contact with each other.

As shown in FIG. 1, the photosensitive drum 1 has a drum gear 1 at one end in the longitudinal direction of a drum-shaped photosensitive member 1b.
a is fixed. The drum gear 1a meshes with a gear (not shown) of the image forming apparatus main body to rotate the photosensitive drum 1 in the direction of arrow A1 in FIG. Rotate. Also, a transfer roller (not shown)
In the configuration of the image forming apparatus main body for driving the
As shown in FIG.
c is provided.

(Developing Apparatus) The developing apparatus includes a developing roller 2 for supplying toner to the photosensitive drum 1, a stirring member (not shown), a toner container and the like. Developing roller 2
Are roughly divided into a portion for supporting the developing sleeve 3 and a portion inside the developing sleeve 3 for supporting the magnet 4.

The developing sleeve 3 has a hollow cylindrical shape made of a non-magnetic material (for example, aluminum), and has a central portion 3a which carries toner and is directly involved in forming a toner image, and other end portions 3b and 3c having a small diameter. Consists of

A developing blade 18 for regulating the thickness of the toner layer is in contact with the central portion 3a (see FIG. 2). The developing blade 18 has a contact portion 18 made of a non-magnetic member (for example, rubber).
a and a supporting portion that supports the contact portion 18a and is fixed to the frame body 15.
18b. Bearings 7 and 8 and sleeve rollers 9 and 10 are provided at both ends 3b and 3c, and a sleeve gear 11 is arranged at one end.

The sleeve rollers 9 and 10 abut against the photosensitive member 1b and the developing sleeve 3 by the force of the spring 17, thereby keeping the gap between the photosensitive member 1b and the developing sleeve 3 constant.
The bearings 7, 8 are supported by the frame 15, and rotatably support the developing sleeve 3.

As described above, the sleeve gear 11 meshes with the drum gear 1a to rotate the developing sleeve 3. When toner agitation is required, a drive train connected to the agitation member is provided, and the agitation member is driven to agitate.

The magnet 4 is made of a ferromagnetic material and has a plurality of magnetic poles. One of the magnetic poles is arranged so as to maximize the magnetic force at the developing position, and the other is arranged at a position where the toner inside the developing frame is attracted onto the developing sleeve 3. As shown in FIG. 1, the magnet 4 also has a central portion 4a having a large diameter and both end portions 4b and 4c having small diameters, similarly to the developing sleeve 3. Each diameter is smaller than the inner diameter of the developing sleeve 3 at the corresponding position. Both end portions 4b and 4c penetrate the developing sleeve 3 and protrude to the outside, and the portions are guided by the frame 15.

When the magnet 4 is mounted on the frame 15,
Although it is necessary to determine a plurality of magnetic poles at predetermined positions, as shown in FIG. 3, by making the shape of one end 4b in the longitudinal direction “D” shape, the posture (angle) thereof is not changed. I support it. Further, the projecting portion of the magnet 4 is
As shown in FIG. 3, it is pressed toward the developing position by springs 12 and 13.

Further, as shown in FIG.
Non-magnetic abutment members 5 and 6 are placed on both ends of the central portion 4a. The outer diameter of the abutting members 5 and 6 is
Is smaller than the inner diameter of the central portion 3a, and the inner diameter is larger than the outer diameter of the central portion 4a of the magnet 4. The thickness dimension is controlled to be within a certain small range.

Accordingly, as shown in FIG. 2, the urging forces of the springs 12 and 13 cause the abutting members 5 and 6 to abut against the outer peripheral surface of the magnet 4 and the inner peripheral surface of the developing sleeve 3. Thereby, the displacement between the magnet 4 and the developing sleeve 3 can be suppressed within the error range of the thickness of the abutting members 5 and 6 which is not more than a certain fixed value. Therefore, the fluctuation of the magnetic force at the developing position can be suppressed to a small error range over the entire area in the longitudinal direction.

In the above-described embodiment, the abutment members 5, 5
Although the case where 6 is on both sides of the magnet 4 is shown, the present invention is not limited to this, and only one may be used. For example, due to the force received by the sleeve gear 11, the sleeve support portion 18 is provided at the end where the sleeve gear 11 is arranged during driving.
b and the magnet support 18b move relative to each other, so that the sleeve support 11
In the case where the magnet 18b and the magnet support 18b hardly move relatively, the same effect as in the above-described embodiment can be expected even if the abutting member and the spring are provided only at the end where the gear is located.

[0027]

The present invention is constructed as described above.
Since the gap between the magnet and the developing sleeve is ensured with high accuracy by the abutting member, the fluctuation of the magnetic force at the developing position can be suppressed small, and a high-quality image without density unevenness can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view illustrating a configuration of a photosensitive drum and a developing device in a longitudinal direction.

FIG. 2 is an explanatory side sectional view of a photosensitive drum and a developing device.

FIG. 3 is a schematic explanatory view of an image forming apparatus equipped with a process cartridge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photoconductor drum 1a ... Drum gear 1b ... Photoconductor 1c ... Transfer drive gear 2 ... Developing roller 3 ... Development sleeve 3a ... Center part 3b, 3c ... End parts 4 ... Magnet 4a ... Center part 4b, 4c ... End parts 5, 6 ... abutting members 7, 8 ... bearings 9, 10 ... sleeve rollers 11 ... sleeve gears 12, 13 ... springs 14, 15 ... frame bodies 16 ... shafts 17 ... springs 18 ... developing blades 18a ... contact portions 18b ... support portions 20 ... Process cartridge 21 ... Charging roller 22 ... Cleaning means 23 ... Developing device 30 ... Transport roller pair 31 ... Transfer roller 32 ... Fixing means

Claims (4)

[Claims] 1. A developing device for supplying a developer by a developing sleeve having a built-in magnet, wherein a striking member is arranged between the magnet and the developing sleeve, and the magnet is connected to the developing member via the striking member. A developing device, wherein the developing device is urged to abut the sleeve. 2. The developing device according to claim 1, wherein the magnet is housed inside a cylindrical developing sleeve, and the abutting members are arranged at both ends in a longitudinal direction of the magnet. 3. A process cartridge detachable from a main body of an image forming apparatus, comprising: a photosensitive drum; and a developing device for developing a latent image formed on the photosensitive drum. A process cartridge using the developing device according to claim 2. 4. An image forming apparatus for forming an image by developing a latent image formed on a photosensitive drum by a developing device, wherein the developing device according to claim 1 or 2 is used as the developing device. Characteristic image forming apparatus.