JP2004093702A - Development apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a development apparatus in which a developing roller can be attached/detached to/from a housing by a simple operation and required positioning accuracy can be ensured. <P>SOLUTION: In the development apparatus, a developing roller 11 is detachably attached to the housing 10 via a bearing 30. When the annular groove 36 of the bearing 30 is fitted to the rib 20 of the housing 10, flat projections 36a formed in three parts of the internal face of the annular groove 36 engage the outer circumferential face of the rib 20. By rotating the bearing 30 in a first radial direction d while keeping the annular groove 36 fitted on the rib 20, a projection 32 slides over the engagement portion 22 and engages its end face 22c, and, also projections 31 and 33 engage engagement portions 21 and 23. Conversely, by rotating the bearing 30 in a second radial direction d' while keeping the projection 32 disengaged from the engagement portion 22 by its elasticity, the projections 31 and 33 disengage from the engagement portions 21 and 23. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a developing device, and more particularly to a developing device that visualizes an electrostatic latent image formed on a photoconductor in an electrophotographic process.
[0002]
[Prior art and problems]
In recent years, a developing device used in an electrophotographic process has been unitized so as to be detachable from a main body of a copying machine or a printer, and is designed so that it can be replaced when a toner is used up or a predetermined expiration date has passed. I have.
[0003]
Such a developing device is replaced and reused if there is any worn part. If the developing roller for supplying the toner to the photoreceptor reaches the end of its life due to abrasion or the like, it is also subject to replacement.
[0004]
By the way, conventionally, the developing roller generally has a structure in which a support shaft is rotatably mounted on a housing via a bearing, so that a dedicated jig or the like is required for attachment and detachment from the housing, and replacement work is extremely complicated. .
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing device capable of attaching and detaching a developing roller to and from a housing by a simple operation and securing necessary positional accuracy.
[0006]
Configuration, operation and effect of the present invention
In order to achieve the above object, a developing device according to the present invention includes a housing accommodating a developer, a developing roller rotatably installed in an opening of the housing, and a support shaft of the developing roller provided in the housing. A housing that rotatably supports the bearing, wherein the housing includes a rib that projects in a cylindrical shape in the axial direction of the developing roller, and a second rib that positions the bearing in the thrust direction and the first radial direction. A first engaging portion, a second engaging portion for positioning the bearing in a second radial direction opposite to the first direction, and a third engaging portion for positioning the bearing in the thrust direction. Wherein the bearing has an annular groove fitted into the cylindrical rib of the housing, and first, second and third engagement portions respectively engaged with the first, second and third engagement portions. An annular groove of the bearing Protrusions are formed on the inner peripheral surface of the housing so as to engage with the outer peripheral surface of the cylindrical rib at three locations at substantially equal intervals in the circumferential direction, and the annular groove is fitted to the cylindrical rib. When the bearing is rotated in the first radial direction in a state in which the second projection is over the second engagement portion and engages with the second engagement portion, the first and third projections are rotated. The bearing is rotated in the second radial direction in a state where the second projection is engaged with the first and third engagement portions and the second projection is disengaged from the second engagement portion by its elasticity. Then, the first and third projections release the engagement with the first and third engagement portions.
[0007]
In the developing device according to the present invention having the above configuration, the bearing is rotated in the first radial direction with the annular groove of the bearing fitted to the cylindrical rib of the housing by a simple operation. The bearing can be fixed to the housing, and the developing roller can be mounted on the housing. On the other hand, the bearing is free from the housing by a simple operation of rotating the bearing in the opposite second radial direction in a state where the second projection is disengaged from the second engaging portion by its elasticity. Then, the developing roller can be removed from the housing.
[0008]
The bearing fits into the cylindrical rib of the housing by its annular groove. At the time of this fitting, since the protrusions formed at three locations at substantially equal intervals in the circumferential direction on the inner peripheral surface of the annular groove engage with the outer peripheral surface of the cylindrical rib, the shaft center of the cylindrical rib and the bearing of the bearing are engaged. The shaft center (that is, the shaft center of the developing roller) matches with high precision, and fitting is performed with appropriate hardness.
[0009]
Further, the bearing is attached to the housing by the first, second, and third projections in a state where the bearing is engaged in the thrust direction and the radial direction. Therefore, the developing roller is rotatably held by the housing with high accuracy in accordance with the coincidence of the axes.
[0010]
In the developing device according to the present invention, it is preferable that the first engagement portion and the second engagement portion are disposed at substantially 180 ° intervals in the circumferential direction. The bearing is regulated in the thrust direction in a well-balanced manner at two opposing positions in the circumferential direction.
[0011]
Also, it is preferable to use a bearing integrally molded from a resin material, since it can be mass-produced at low cost.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a developing device according to the present invention will be described with reference to the accompanying drawings.
[0013]
As shown in FIG. 1, a developing device according to one embodiment of the present invention includes a housing 10 for housing a developer and a developing device for supplying toner to the surface of the photosensitive drum 1. The roller 11, a developer feeding member 12, a developer supply roller 13, a toner regulating / charging member 14, and a seal / static elimination member 15 for preventing leakage of toner.
[0014]
The developing roller 11 is a metal roller whose outer peripheral surface is covered with a resistor layer made of rubber. The developing roller 11 faces the photosensitive drum 1 rotating in the direction of arrow a via the developing area 2 at a minute interval. It is driven to rotate in the direction.
[0015]
This developing device is based on a one-component developing method including only toner containing no carrier, and the toner in the first chamber 10a of the housing 10 is sent to the second chamber 10b by the feeding member 12, and further supplied to the supply roller. 13, is supplied to the outer peripheral surface of the developing roller 11, and is charged to a predetermined potential by passing through the regulating / charging member 14. When a developing bias voltage in which a DC voltage and an AC voltage are superimposed is applied to the developing roller 11 from a power supply unit (not shown), the toner on the developing roller 11 flies onto the photosensitive drum 1 in the developing area 2. And visualizes the electrostatic latent image. The behavior (developing action) of the toner in such non-contact one-component development is well known in the art, and a detailed description thereof will be omitted.
[0016]
Next, the structure of the bearing portion that rotatably supports the developing roller 11 and the operation of attaching and detaching the bearing portion will be described.
[0017]
As shown in FIG. 2, a rib 20 protruding in a cylindrical shape in the axial direction of the developing roller 11 and first, second and third engaging portions 21 for positioning the bearing 30 are provided on a side wall of the housing 10. , 22, and 23 are formed.
[0018]
The bearing 30 is integrally formed of a suitable resin material, and has first, second and third protrusions 31, 32, and 33 formed on the outer peripheral surface thereof, and the developing roller 11 is formed on the axial center thereof. A cylindrical portion 35 for rotatably holding the end of the support shaft 11a is formed, and an annular groove 36 for fitting into the cylindrical rib 20 is formed around the cylindrical portion 35.
[0019]
Further, on the inner peripheral surface of the annular groove portion 36, as shown in FIG. 3, flat protrusions 36a are formed which are engaged with the outer peripheral surface of the cylindrical rib 20 at three positions at equal intervals in the circumferential direction. ing. That is, the diameter of one inner peripheral surface 36b (also the outer peripheral surface of the cylindrical portion 35) of the annular groove 36 is equal to the diameter of the inner peripheral surface of the cylindrical rib 20, and the inscribed circle of the three flat protrusions 36a. Is equal to the diameter of the outer peripheral surface of the cylindrical rib 20.
[0020]
The annular groove 36 of the bearing 30 is fitted into the cylindrical rib 20 by inserting the cylindrical portion 35 into the cylindrical rib 20 in the first thrust direction indicated by the arrow c. At the time of this fitting, the inner peripheral surface of the annular groove portion 36 engages with the outer peripheral surface of the cylindrical rib 20 at three equally spaced protrusions 36 a, so that the axial center of the cylindrical rib 20 and the shaft of the bearing 30 are engaged. The center (that is, the axis of the developing roller 11) is accurately matched with the core, and the fitting is performed with an appropriate hardness.
[0021]
The first, second, and third projections 31, 32, and 33 formed on the bearing 30 are respectively engaged with the first, second, and third engagement portions 21, 22, and 23 formed on the housing 10. It is removable.
[0022]
More specifically, the first engagement portion 21 positions the bearing 30 in the first thrust direction c and the second thrust direction c ′ opposite thereto by engaging the first projection 31, and the first engagement portion 21 engages with the first projection 31. In the radial direction d. The first projection 31 includes a projecting piece 31a having an opening 31b and a projecting piece 31c having an opening 31d (see FIG. 2B). The opening 31b is a mold for forming the projecting piece 31c during resin molding. This is a portion formed for stamping out a portion. When the bearing 30 rotates in the radial direction d, the first engagement portion 21 protrudes into the opening 31d, and the first projection 31 is positioned in the thrust directions c and c '. At the same time, the projection 31c abuts on the end face 21a, whereby the first projection 31 is positioned in the radial direction d.
[0023]
The second engaging portion 22 is for positioning the bearing 30 in the second radial direction d ′ opposite to the first radial direction d by engaging the second protrusion 32. The second projection 32 is a plate-like body having an appropriate elasticity in the thickness direction, and the second engaging portion 22 includes inclined surfaces 22a and 22b and an end surface 22c. When the bearing 30 rotates in the radial direction d, the second protrusion 32 climbs over the inclined surfaces 22a and 22b and engages with the end surface 22c to be positioned in the radial direction d '.
[0024]
The third engaging portion 23 is for positioning the bearing 30 in the thrust directions c and c ′ by engaging the third protrusion 33. The third projection 33 is a rigid plate-like body, and the third engagement portion 23 is formed in a groove shape. When the bearing 30 rotates in the radial direction d, the third protrusion 33 enters the third engagement portion 23 and engages with the opposing inner surface of the engagement portion 23 to position in the thrust direction c, c ′. Is done.
[0025]
The operation of attaching and detaching the bearing 30 having the above configuration is as follows. That is, when the bearing 30 is rotated in the first radial direction d as shown in FIG. 4 in a state where the annular groove portion 36 is fitted to the cylindrical rib 20 of the housing 10, the second projection 32 The first and third projections 31 and 33 engage with the first and third engagement portions 21 and 23, respectively, while engaging with the end surface 22c of the first engagement portion 22 (see FIG. 5). Thus, the bearing 30 is positioned and fixed to the housing 10 in the thrust direction c, c ′ and the radial direction d, d ′. At the same time, the developing roller 11 is also positioned in the housing 10 via the bearing 30, and is rotatably fixed. FIG. 6 shows this fixed state.
[0026]
On the other hand, when the bearing 30 is rotated in the radial direction d ′ in a state in which the second projection 32 is bent in the thrust direction c ′ by its elasticity and disengaged from the second engagement portion 22, The first and third projections 31, 33 release the engagement with the first and third engagement portions 21, 23. As a result, the bearing 30 is detached from the housing 10, and the developing roller 11 can be detached from the housing 10.
[0027]
In this embodiment, the bearing 30 can be fixed to the housing 10 and the developing roller 11 can be easily mounted on the housing 10 by a simple operation of rotating the bearing 30 in the first radial direction d. On the other hand, by a simple operation of rotating the bearing 30 in the second radial direction d ′ in a state where the second projection 32 is disengaged from the second engagement portion 22 by its elasticity, the bearing 30 is rotated. The developing roller 11 can be easily detached from the housing 10 by leaving the housing 10 free.
[0028]
Further, since the bearing 30 is attached to the housing 10 by the projections 31, 32, 33 in a state of being engaged in the thrust directions c, c 'and the radial directions d, d', the bearing 30 is misaligned with respect to the housing 10. It is fixed without. Further, as described above, the bearing 30 has the annular groove 36 having three flat protrusions 36a fitted to the cylindrical rib 20 and is attached to the rib 20 with their axes aligned. The shaft center accuracy is also good.
[0029]
Further, in the present embodiment, since the engaging portions 31 and 33 of the bearing 30 are disposed at intervals of 180 ° in the circumferential direction, the bearing 30 is balanced in the thrust direction c at two circumferentially opposed positions. , C ′.
[0030]
(Other embodiments)
The developing device according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the gist.
[0031]
In particular, as a basic system of the developing device, a non-contact system having a gap in a developing area, a system in which a developing roller and a photosensitive drum are in contact, or a two-component developer including a carrier and a toner is used. May be used.
[0032]
The shape of the three projections for fitting the bearing to the cylindrical ribs with their axes aligned, and the details of the three pairs of projections and the engagement portion that engage with each other are arbitrary.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a basic configuration of a developing device according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view of a bearing portion in the developing device.
FIG. 3 is a front view showing a bearing used in the developing device.
FIG. 4 is an explanatory diagram showing when the mounting of the bearing in the developing device is started.
FIG. 5 is an explanatory diagram showing when the mounting of the bearing in the developing device is completed.
FIG. 6 is a sectional view taken along line XX of FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum 10 ... Housing 11 ... Developing roller 20 ... Cylindrical ribs 21, 22, 23 ... First, second and third engaging parts 30 ... Bearings 31, 32, 33 ... First, second and third Third protrusion 36: annular groove 36a: protrusion

Claims (3)

A developing device comprising: a housing for accommodating a developer; a developing roller rotatably installed in an opening of the housing; and a bearing rotatably supporting a support shaft of the developing roller with respect to the housing.
The housing includes a rib protruding in a cylindrical shape in the axial direction of the developing roller, a first engagement portion for positioning the bearing in the thrust direction and the first radial direction, and a bearing opposite to the first direction. A second engaging portion for positioning the bearing in the second radial direction, and a third engaging portion for positioning the bearing in the thrust direction.
The bearing has an annular groove fitted into a cylindrical rib of a housing, and first, second and third projections respectively engaged with the first, second and third engagement portions. ,
Projections are formed on the inner peripheral surface of the annular groove portion of the bearing at three locations at substantially equal intervals in the circumferential direction with respect to the outer peripheral surface of the cylindrical rib of the housing,
When the bearing is rotated in the first radial direction in a state where the annular groove portion is fitted to the cylindrical rib, the second projection rides over the second engagement portion and engages with the second engagement portion. Engaging and the first and third projections engage with the first and third engaging portions,
When the bearing is rotated in the second radial direction in a state where the second projection is disengaged from the second engagement portion by its elasticity, the first and third projections become the first and third projections. Disengaging the third engagement portion;
A developing device characterized by the above-mentioned. 2. The developing device according to claim 1, wherein the first engagement portion and the second engagement portion are disposed at substantially 180 degrees in a circumferential direction from each other. The developing device according to claim 1, wherein the bearing is formed integrally from a resin material.

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