JP2618620B2 - Developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a developing device using a magnet roller applied to a developer conveyance of an image forming apparatus.

(Prior art) Conventionally, this type of magnet roll has a sheet magnet attached around a support shaft made of a non-magnetic material such as aluminum or a magnetic material such as iron, or the support shaft is fitted to a cylindrical magnet. It is configured in combination. However, in a developing device of a magnet roll fixed type, a supporting method of fixing a support shaft to a side wall of the developing device is adopted.

(Problems to be Solved by the Invention) However, in the case of such a conventional technique, the magnet roll requires a support shaft, and thus has the following problems. First, since the magnet roll has a support shaft made of a material having a different shape at the center of the magnet roll and having a different magnetic permeability and magnetic permeability from the magnet, magnetic design of the magnet is difficult. Secondly, since the support shaft requires a certain thickness in terms of strength, especially in the case of a small-diameter magnet roll having a diameter of 20 mm or less, the ratio of the volume of the magnet to the volume of the entire magnet roll is reduced. Magnetic force is difficult to obtain. Third, in the step of attaching the magnet to the support shaft or the step of fitting the support shaft to the magnet, it is difficult to obtain the positional accuracy between the support shaft and the magnet. Fourth, since a step of fixing the magnet to the support shaft is required, the manufacturing process of the magnet roll becomes complicated and the cost is increased, and the cost of the developing device is increased.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an inexpensive developing device by using a magnet roll that does not require a support shaft. It is in.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a rotating non-magnetic sleeve, a magnet roll included in the sleeve and having a plurality of magnetic poles, and a side wall of an apparatus main body. Wherein the magnet roll is provided by mixing a magnetic powder with a synthetic resin or rubber and forming a columnar magnet roll main body having a predetermined magnetic pole pattern in the circumferential direction, and integrally formed with the magnet roll main body at the same time. A regulating portion for regulating the rotation of the magnet roll,
The magnet roll is fixedly supported by engaging a regulating portion with an engaging portion provided on the side wall.

(Example) Hereinafter, the present invention will be described based on an illustrated example.

FIG. 1 is a perspective view showing a first embodiment of a magnet roll applied to a developing device according to a first embodiment of the present invention described later.

In the figure, reference numeral 1 denotes a cylindrical magnet roll main body, and magnetic poles 2, 2,..., Which are magnetized linearly in the axial direction, are surrounded by N · S in the circumferential direction around the magnet roll main body 1. The poles are arranged alternately. The magnet roll body 1 is made of a thermoplastic or thermosetting synthetic resin or rubber such as nylon resin, vinyl chloride, vinyl acetate, polyethylene chloride, nitrile rubber, or ferrite.
A magnetic material made of a powder such as a rare-earth magnet is mixed and molded into a desired shape having a regulation portion for regulating the rotation of the magnet roll at both ends of the main body by injection molding or the like (that is,
The main body and the regulating parts at both ends are integrally molded at the same time),
During or immediately after molding, a magnetic field is applied to orient the magnetic body in a certain direction, and then magnetized to a desired magnetic pole pattern. (A roll is formed by the same forming method in each embodiment.) The diameter of the magnet roll main body 1 of each embodiment is arbitrary, but for example, a magnet roll having a length of 5 to 30 mm is used, and the length of the magnet roll is 1 mm. Although it depends on the maximum width of the transfer paper such as a copying machine to be used, A4 size paper of 210 mm is used.

By the way, at both ends 3, 3 of the magnet roll main body, an engaging portion 4 as a restricting portion for restricting the rotation of the magnet roll relatively engaging with the engaging portion provided at the mounting location.
Is provided. In the illustrated embodiment, a flat portion 7 perpendicular to the end surface 6 is formed on the peripheral surface 5 side of both end portions 3 of the magnet roll over a length l in the axial direction, and the both end portions 3 are themselves engaged. The joint 4 is formed. The length l of the flat portion 7 is set within a range that does not adversely affect the magnetic characteristics of the magnet roll in development.

FIGS. 4 to 8 show different shapes of the engaging portions 4 formed by forming the flat portions 7 perpendicular to the end surfaces 6 at both end portions 3 of the magnet roll main body 1 as described above. It is. In this case, as in FIG. 1, when the flat portion 7 is provided asymmetrically with respect to the axis of the magnet roll main body 1 as shown in FIGS. The mounting position in the direction can be specified.

FIG. 2 shows a developing device according to a first embodiment of the present invention using the magnet roll configured as described above.

In the figure, reference numeral 8 denotes a non-magnetic sleeve which rotates in the direction of the arrow, and 9 denotes a magnet roll which is included in the non-magnetic sleeve 8 and formed as shown in FIG. Reference numeral 10 denotes a blade serving as a magnetic material applying means, which is disposed so as to maintain a small gap from the surface of the sleeve 8 and applies the magnetic toner 12 in the hopper 11 onto the sleeve with a magnetic force while regulating the thickness. . Reference numeral 13 denotes a latent image holding member such as an electrostatic image, which moves in the direction of the arrow, and undergoes development at a development position T by a uniform toner layer.

FIG. 3 shows a mounting portion between the developing device and the magnet roll. In the drawing, reference numeral 14 denotes a side wall of the apparatus main body. The lower end of the side wall 14 is formed to be thick, and the lower end inner surface of the side wall 14 is provided at both ends 3 of the magnet roll main body 1. An engaging portion 15 that relatively engages with the engaging portion 4 is provided. That is, on the inner surface of the lower end portion of the side wall 14 of the developing device, there is provided an engaging portion 15 having a recess having the same shape as the engaging portion 4 of the magnet roll main body 1. A flat portion 16 is formed at a position corresponding to the flat portion 7 of the engaging portion on the side. In the figure, reference numeral 17 denotes a bearing for rotatably supporting the sleeve 8 on the side wall 14 of the developing device, and the sleeve 8 is rotationally driven by driving means (not shown).

Thus, the magnet roll 9 engages the engaging portions 4 provided at both ends 3 of the magnet roll main body 1 with the engaging portions 15 provided on the side wall 14 of the developing device. It can be accurately mounted at a desired setting position without being twisted in the circumferential direction.

FIG. 9 shows a second embodiment of the magnet roll applied to the developing device according to the second embodiment to be described later, and the same parts as those in the first embodiment are denoted by the same reference numerals. Then, in this embodiment, the engaging portions 4 provided at the both end portions 3 of the magnet roll main body 1 are formed by the concave portions 18 provided in the end surface 6. In the illustrated embodiment, a square recess 18 is provided on the end face 6 of the magnet roll body symmetrically with respect to the axis, and the depth of the recess 18 is:
The range is set so as not to adversely affect the magnetic characteristics in development.

FIGS. 10 to 13 show different shapes of the recesses 18, and the recesses 18 are provided with asymmetrical portions 19. FIG.

FIG. 14 shows a second embodiment of the developing device using the magnet roll according to the second embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals and described. In this embodiment, an engaging portion 15 having the same shape as the engaging portion 4 of the magnet roll main body is provided on the side wall 14 of the developing device. Both ends 3 of the magnet roll main body are fitted in recesses 20 provided in the side wall 14.

FIG. 15 shows a third embodiment of a magnet roll applied to a developing device according to a third embodiment of the present invention to be described later, and the same parts as those in the first embodiment are denoted by the same reference numerals. In this embodiment, the engaging portions 4 provided at both ends 3 of the magnet roll main body 1 are formed by grooves 21 provided on the peripheral surface 5 of the both ends 3. In the illustrated embodiment, a small rectangular groove 21 is provided at both end portions 3 of the magnet roll body so that one of the grooves 3 is open to the end face 6, and the size of the groove 21 is inconvenient for development due to magnetic characteristics. It is set within the range that does not affect.

16 to 20 show different shapes of the groove 21. FIG.

FIG. 21 shows a third embodiment of the developing device using the magnet roll according to the third embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals and described. In this embodiment, a recess 22 is provided in the side wall 14 of the developing device for fitting both ends 3 of the magnet roll main body, and the side wall 14 has the same protrusion as the groove 21 of the magnet roll main body. Is provided.

FIG. 22 shows a fourth embodiment of a magnet roll applied to a developing device according to a fourth embodiment of the present invention to be described later, and the same parts as those in the first embodiment are denoted by the same reference numerals. To explain, in this embodiment, the engaging portions 4 provided on both ends 3 of the magnet roll main body 1 are composed of protrusions 23 provided on the end surfaces 6 of the both ends 3. In the illustrated embodiment, a quadrangular prism-shaped projection 23 is provided vertically at the center of the end face 6 of the magnet roll main body. In addition,
The projection 23 is not limited to a quadrangular columnar shape, but may be a columnar or triangular columnar shape, and may be provided at a position other than the center of the end surface 6 of the magnet roll main body.

FIG. 23 shows a fourth embodiment of the developing device using the magnet roll according to the fourth embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals and described. In this embodiment, an engaging portion 15 having a through hole having the same shape as the projection 23 of the magnet roll main body is provided on the side wall 14 of the developing device.

The magnet roll according to the embodiment may be formed in a polygonal column shape other than the column shape.

(Effects of the Invention) The present invention has the above-described configuration and operation. The present invention relates to a mechanism in which a regulating portion for regulating rotation of a magnet roll provided integrally with a magnet roll body is provided on a side wall of the developing device body. Since the magnet roll is fixedly supported by engaging the regulation portion with the joint portion, the support shaft of the magnet roll is not required, and only the engagement portion with which the regulation portion engages is provided on the side wall of the developing device main body. An inexpensive developing device can be provided very easily with a small number of components.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a magnet roll applied to a developing device according to a first embodiment of the present invention.
The figure is a longitudinal sectional view showing one embodiment of the developing device according to the present invention,
FIG. 3 is a partial longitudinal sectional view showing a developing device according to a first embodiment of the present invention using the magnet roll shown in FIG.
8 are perspective views showing a modification of the magnet roll shown in FIG. 1, and FIG. 9 is a perspective view showing a second embodiment of the magnet roll applied to the developing device according to the second embodiment of the present invention. FIGS. 10 to 13 are perspective views showing a modification of the magnet roll shown in FIG. 9, and FIG. 14 is a developing device according to a second embodiment of the present invention using the magnet roll shown in FIG. FIG. 15 is a perspective view showing a third embodiment of a magnet roll applied to the developing device according to the third embodiment of the present invention, and FIGS. 16 to 20 are shown in FIG. FIG. 21 is a perspective view showing a modification of the magnet roll shown in FIG. 21, FIG. 21 is a partial longitudinal sectional view showing a developing device according to a third embodiment of the present invention using the magnet roll shown in FIG. 15, and FIG. A perspective view showing a fourth embodiment of the magnet roll applied to the developing device according to the fourth embodiment. , FIG. 23 is a partial longitudinal sectional view showing a developing device according to a fourth embodiment of the present invention using a magnet roll as shown in Figure 22. DESCRIPTION OF SYMBOLS 1 ... Magnet roll main body 2 ... Magnetic pole 3 ... End 4 ... Engaging part (restricting part), 8 ... Sleeve 9 ... Magnet roll, 14 ... Side wall 15 ... Engaging part

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-195261 (JP, A) JP-A-61-206204 (JP, A)

Claims (1)

(57) [Claims] 1. A developing device having a rotating non-magnetic sleeve, a magnet roll included in the sleeve and having a plurality of magnetic poles, and a side wall of an apparatus body, wherein the magnet roll is made of synthetic resin or magnetic resin powder. A columnar magnet roll main body having a predetermined magnetic pole pattern in the circumferential direction mixed with rubber, and a restricting portion for restricting rotation of the magnet roll provided by integral molding with the magnet roll main body, A developing device, wherein a magnet roll is fixedly supported by engaging a regulating portion with an engaging portion provided on a side wall.