JPH08275443A - Motor and image forming apparatus utilizing the same - Google Patents

Abstract

PURPOSE: To assure good heat radiation of a heating generating part particularly of rotor and rotating shaft. CONSTITUTION: A motor comprises a hollow rotating shaft 1 having both ends fixed, a rotor 3 rotatably provided at the external circumference of this rotating shaft 1, a magnet 4 and a stator core 6 for rotating the rotor 3 and a bearing means for rotatably supporting the rotor 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is particularly applicable to laser printers,
The present invention relates to a motor used in an optical deflector used in a laser beam writing system of a digital copying machine and an image forming apparatus using the motor.

[0002]

2. Description of the Related Art Conventionally, a motor shown in FIG. 4 has been known. Reference numeral 41 in the drawing denotes a rotary shaft having one side (lower end side) fixed to the housing 42 and a spiral groove 41a formed on the peripheral surface. Here, the rotary shaft 41 is fixed to the housing 42 by press fitting or adhesion. The rotating shaft 41
A rotor 43 is provided on the outer peripheral portion of. This rotor
A magnet 44 is provided on the outer peripheral portion of 43. On the outside of the magnet 44, a stator core 46, around which a coil 45 is wound, is arranged so as to face the magnet 44 in a circumferentially fixed manner and fixed to the housing 42. A PC board having a position detecting element (Hall element or the like) 47 around the lower portion of the rotating shaft 41.
48 is fixedly arranged in the housing 42.

A polygon mirror 49 is arranged around the upper end of the rotor 41 by a pressing plate 50. A thrust bearing 51 (due to the magnetism of the magnet) is fixedly arranged in the housing 42 between the polygon mirror 49, the magnet 44, and the stator core 46.
Here, the thrust bearing 51 has a structure in which a magnet (not shown) different from the magnet 44 is sandwiched between upper and lower magnetic bodies, and the stator core 46 forms a magnetic path. A cover 53 is attached to the cover housing 42 so as to seal the pressing plate 50, the polygon mirror 49, the thrust bearing 51, etc. located on the upper end side of the rotary shaft 41. Here, a glass plate 53 that transmits laser light is attached to the cover 52 portion located at a part of the peripheral portion of the polygon mirror 49.

The operation of the motor having such a structure is as follows. The motor detects the position of the magnet 44 of the rotor 43 by the position detecting element 47 installed on the PC board 48 and energizes the coil 45 of the stator core 46 to rotate the rotor 43 by magnetic attraction. When the rotor 43 rotates, the rotation axis
A fluid (air) bearing is formed by the spiral groove 41a formed in 41 to form a radial bearing. Then, a magnetic path is formed by using the magnet 44, and the rotor 43 is rotated by suction to rotate the polygon mirror 49 and rotate the cover 52.
The laser light is scanned through the glass 53 provided on the optical axis to deflect the light.

[0005]

By the way, in the conventional motor, the rotor 43 and the rotary shaft 41 become hot when the motor is used. However, since the conventional motor has a structure in which the lower end of the solid rotating shaft 41 is fixed to the housing 42, there is a problem that the rotor 43 and the rotating shaft 41 cannot sufficiently dissipate heat.

The present invention has been made in consideration of such circumstances, and a motor capable of improving heat radiation of a heat generating portion, particularly a rotor and a rotary shaft by improving a rotary shaft as compared with a conventional motor, and this motor An object is to provide an image forming apparatus using the same.

[0007]

According to a first aspect of the present invention, a hollow rotary shaft having both ends fixed, a rotary body rotatably provided on an outer peripheral portion of the rotary shaft, and the rotary body are rotated. A motor comprising rotating means and bearing means for rotatably bearing the rotating body.

According to a second aspect of the present invention, a hollow rotary shaft having one side fixed, a rotary body rotatably provided on an outer peripheral portion of the rotary shaft, a rotating means for rotating the rotary body, and the rotary body. And a bearing means for rotatably bearing the body.

According to a third aspect of the present invention, a solid rotary shaft whose both ends are fixed, a rotary body rotatably provided on an outer peripheral portion of the rotary shaft, a rotating means for rotating the rotary body, and And a bearing means for rotatably bearing a rotating body.

A fourth invention of the present application is an image forming apparatus characterized by comprising an apparatus main body, the motor, and a photosensitive medium for receiving light scanned by the motor. In the present invention, the term “rotating body” refers to a member that rotates together with the rotating shaft, such as the rotor 3 shown in FIG.

In the present invention, the rotating means means, for example, a stator core 6 and a magnet 4 around which the coil shown in FIG. 1 is wound.
A member for rotating the rotating body is shown. In the present invention, the bearing means means, for example, a spiral groove formed on the peripheral surface of the rotating shaft in FIG.

In the present invention, the rotating mirror may be, for example, a polygon mirror. In the present invention, the upper and lower sides of the rotary shaft are fixed by, for example, a housing, a cover, an upper part by a cover, and a lower part by a housing.

[0013]

The operation of the present invention is as follows. The motor is P
The position detecting element installed on the C plate detects the position of the magnet of the rotor and energizes the coil of the stator yoke to rotate the rotor by magnetic attraction. When the rotor rotates, a fluid (air) bearing is formed by the spiral groove formed on the rotating shaft to form a radial bearing. Then, a magnetic path is formed using a magnet, and the rotor is rotated by suction to rotate the polygon mirror, and the laser beam is scanned through the glass plate provided on the cover.
Performs light deflection.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 Reference is made to FIG. Reference numeral 1 in the drawing denotes a rotary shaft having a lower end side fixed to the housing 2 and an upper end portion fixed to a cover described later, and a spiral groove (not shown) formed on the outer peripheral surface. Here, the rotary shaft 1 is fixed to the housing 2 by press fitting or adhesion. The rotating shaft 1
A rotor 3 as a rotating body is provided on the outer peripheral portion of. A magnet 4 is provided on the outer peripheral portion of the rotor 3. Outside the magnet 4, the magnet 4
A stator core 6 around which a coil 5 is wound is fixedly arranged in the housing 2. Here, the stator core 6 constitutes a rotating means together with the magnet 4. A PC plate 8 having a position detecting element (Hall element or the like) 7 is fixed to the housing 2 and arranged around the lower portion of the rotary shaft 1.

A polygon mirror 9 as a rotating mirror is arranged around the upper end side of the rotor 3 by a pressing plate 10. A thrust bearing 11 (due to the magnetism of a magnet) is fixedly disposed in the housing 2 between the polygon mirror 9 and the stator core 6 and the coil 5. Here, the thrust bearing 11 includes a thrust bearing 11a closer to the rotor side and a thrust bearing 11b closer to the stator core 6 and the coil 5 side. The thrust bearings 11a and 11b have a structure in which a magnet (not shown) different from the magnet 4 is sandwiched between upper and lower magnetic bodies, and the stator core 6 forms a magnetic path. A cover 12 is attached to the housing 12 so as to seal the pressing plate 10, the polygon mirror 9, the thrust bearing 11 and the like located on the upper end side of the rotary shaft 1. Here, a glass plate 13 that transmits laser light is attached to the cover 12 portion located at a part of the peripheral portion of the polygon mirror 9.

The operation of the motor having such a structure is as follows. The motor detects the position of the magnet 4 of the rotor 2 by the position detecting element 7 installed on the PC board 8 and energizes the coil 5 of the stator core 6 to rotate the rotor 3 by magnetic attraction. When the rotor 3 rotates, the spiral (groove) groove formed in the rotary shaft 1 forms a fluid (air) bearing and becomes a radial bearing. And the magnet 4
To form a magnetic path, and the rotor 3 is rotated by suction to rotate the polygon mirror 9 to scan the laser light through the glass 13 provided on the cover 12 to perform optical deflection.

According to the motor of the first embodiment, the rotary shaft 1
Since the upper and lower ends are fixed to the cover 12 and the housing 2 and both end surfaces of the rotating shaft 1 are exposed, even if the heat generating portion of the motor, especially the rotor 3 and the rotating shaft 1 become hot when the motor is used. Since the hollow rotating shaft 1 has good air permeability, the heat from the rotor 3 and the rotating shaft 1 can be easily radiated to the outside, and the cooling time of the motor can be shortened as compared with the conventional motor. it can.

Further, the rotary shaft 1 has a cover 12 and a housing 2.
Since it is fixed to, the heat of the rotating shaft can be transferred to both to dissipate heat, and the heat dissipation efficiency is improved. Further, the air is satisfactorily circulated in the upper region and the lower region with respect to the motor, and there is also an effect of preventing an excessively high temperature region from being generated in the incorporated device.

(Embodiment 2) Referring to FIG. However, in FIG.
The same members as and are denoted by the same reference numerals, and the description thereof will be omitted. Only the essential parts will be described. The motor of FIG. 2 is characterized by having a hollow rotary shaft 21 whose lower end is fixed to the housing 2 but whose upper end is not fixed and which is free as compared with that of FIG.

According to the motor of the second embodiment, since the lower end side is opened, even if the heat generating portion of the motor, especially the rotor 3 and the rotary shaft 1 become high in temperature when the motor is used, the hollow rotary shaft 1 does not move. Since the inside and the lower end side are communicated with each other, the heat from the rotor 3 and the rotating shaft 1 can be easily radiated to the outside, and the cooling time of the motor can be shortened as compared with the conventional motor.

(Embodiment 3) Referring to FIG. However, in FIG.
The same members as and are denoted by the same reference numerals, and the description thereof will be omitted. Only the essential parts will be described. The motor of FIG. 3 is characterized in that it has a solid rotary shaft 31 whose lower end is fixed to the housing 2 and whose upper end is fixed to the cover 12, as compared with that of FIG.

According to the motor of the third embodiment, the rotating shaft 31
Although it is solid, since both ends are fixed to the cover 12 or the housing 2, even if the rotating shaft 1 of the motor becomes hot during use of the motor, the heat of the rotating shaft 1 can be efficiently transferred. The heat can be radiated to the outside, and the cooling time of the motor can be shortened as compared with the conventional motor.

The motor of the present invention is not limited to the polygon mirror having the rotating mirror as in the above embodiments. Also,
If the motor 14 is incorporated in an image forming apparatus such as a copying machine as shown in FIG. 5, it is possible to reduce the local temperature rise in the equipment. In FIG. 5, reference numeral 54 is a scanner unit that houses the motor 14, the folding mirror 55 and a part of the light receiving portion 55, and reference numeral 55 is a photosensitive drum that receives the scanning light.

[0024]

As described above in detail, according to the present invention,
It is possible to provide a highly reliable motor that can improve heat radiation of a heat generating portion, particularly a rotor and a rotary shaft by improving a rotary shaft as compared with a conventional motor, and an image forming apparatus using the motor.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a motor according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a motor according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of a motor according to a third embodiment of the invention.

FIG. 4 is a schematic sectional view of a conventional motor.

5 is an explanatory view of a pixel forming device using the motor of FIG.

[Explanation of symbols]

1,21,31 ... Rotary shaft, 2 ... Housing, 3
... rotor, 4 ... magnet, 5 ... coil,
6 ... Stator core, 7 ... Position detection element,
8 ... PC plate, 9 ... Polygon mirror, 10 ... Pressing plate, 11 ... Thrust bearing, 12 ... Cover, 13 ... Glass plate.

Claims (6)

[Claims] 1. A hollow rotary shaft having both ends fixed, a rotary body rotatably provided on an outer peripheral portion of the rotary shaft, a rotating means for rotating the rotary body, and a rotatable rotary body. A motor comprising a bearing means for bearing. 2. A hollow rotary shaft having one side fixed, a rotary body rotatably provided on an outer peripheral portion of the rotary shaft, a rotating means for rotating the rotary body, and a rotatable rotary body. A motor comprising a bearing means for bearing. 3. A solid rotary shaft having both ends fixed, a rotary body rotatably provided on an outer peripheral portion of the rotary shaft, a rotating means for rotating the rotary body, and the rotary body being rotatable. And a bearing means for bearing on the motor. 4. The motor according to claim 1, wherein a rotary mirror is provided on one end side of the rotary shaft. 5. The motor according to claim 1, wherein the upper and lower sides of the rotary shaft are fixed by a housing and a cover. 6. An image forming apparatus comprising: an apparatus main body; a motor according to claim 4 or 5; and a photosensitive medium that receives light scanned by the motor.