JP2846685B2 - Rotating body balance adjustment structure - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating body balance adjusting structure, and more particularly to a rotating body balance adjusting structure in a scanner motor used in a laser printer, a digital copying machine, or the like.

(Prior Art) Recently, laser printers and the like have been spurred to operate at higher speeds. For example, it has been required to increase the printing speed to that of a general copying machine. For this reason, a scanner motor capable of rotating a rotating polygon mirror (polygon mirror) several thousands per minute is required, and the structure for adjusting the balance of the rotating body is extremely important.

As a conventional balance adjusting structure of this kind of rotating body, for example, a structure in which a hole is formed in the rotating body to remove the weight, or a rotating body as described in Japanese Utility Model Application Laid-Open No. 62-61165. There is a method in which holes and grooves are processed in advance, and an adhesive balance adjuster is embedded in the holes and grooves to add weight. Further, Japanese Patent Application Laid-Open No. 1-174243 discloses a configuration in which tapped holes are formed at predetermined angular intervals in an outer peripheral portion of a rotating body, and a screw member for balance adjustment is attached to the tapped holes.

(Problems to be Solved by the Invention) However, in such a conventional rotating body balancing adjustment structure, it takes time and effort to machine a hole, a groove, or a tapped hole in the rotating body, and it is necessary to separately provide a screw part. However, there is a problem that the cost is increased due to the presence of the surface, and the mirror surface of the rotary polygon mirror is easily stained by chips or the like generated during this processing.

(Object of the Invention) Accordingly, an object of the present invention is to provide a low-cost balance adjustment structure of a rotating body that does not require drilling or grooving of the rotating body.

(Constitution of the Invention) In order to achieve the above-mentioned object, the present invention provides an image forming apparatus, comprising: a rotating body including a rotating polygon mirror provided in a scanner motor;
Forming a magnet portion having an annular wall formed substantially at the same position as the center of gravity of the rotating body in the rotation axis direction of the rotating body, and attaching an adhesive balance adjusting agent to an inner peripheral wall surface of the annular wall of the magnet portion; In this case, the balance of the rotating body is adjusted.

 Hereinafter, the present invention will be described based on examples.

1 and 2 show an embodiment of the present invention, in which the present invention is applied to a scanner motor for a laser printer.

 First, the configuration will be described.

1 and 2, reference numeral 1 denotes a cylindrical housing, 2 denotes a rotating shaft which is supported by the housing 1 via bearings 3A and 3B, 4
Is a flange member fixed coaxially to the rotary shaft 2 and 5 is a rotary polygon mirror fitted to the flange member 4 and fixed to the wave washer 6 and the washer presser 7. A yoke 8 is bonded or caulked to the flange member 4, and the yoke 8 is connected to the magnet member 11 at the outer periphery. The magnet member 11 has a motor magnet part 12 and an FG magnet part 13 formed integrally from a magnetic material. The motor magnet part 12 faces the motor coil 15 on the iron substrate 14 supported by the housing 1. , FG magnet section 13 faces a tooth-shaped pattern coil (not shown) provided on iron substrate 14. The motor magnet part 12 and the motor coil 15 are for driving the magnet member 11 to rotate the rotary polygon mirror 5, and the FG magnet part 13 is magnetized so that the N pole and the S pole are alternately arranged in the circumferential direction. ,
The FG magnet section 13 and the pattern coil constitute a frequency generator for detecting the rotation speed of the magnet member 11. These rotating shaft 2, flange member 4, rotating polygon mirror 5,
The wave washer 6, the washer presser 7, the yoke 8, and the magnet member 11 are combined to form a rotating body 16 as a whole.
Is composed.

On the other hand, an annular wall 18 having an inner peripheral wall surface 17 is integrally formed on the outermost peripheral portion of the magnet member 11 and near the position of the center of gravity in the axial direction. (E.g., known as the trade name "Dreamweight"). The adhesive balance adjuster 19 is used to reduce the amount of unbalance (the amount of unbalance = unbalance mass m × corrected surface radius r) of the rotating body 16 so as to reduce the annular wall.
For example, several mg to several hundred mg are adhered to the inner peripheral wall 17 of 18.

 Next, the operation will be described.

When the motor coil 15 is excited, the magnet member 11 in which the motor magnet unit 12 faces the motor coil 15 rotates, and the rotating body 16 rotates. Further, an AC voltage having a frequency corresponding to the rotation speed of the magnet member 11 is generated between both ends of the pattern coil, and thereby the rotation speed of the rotating body 16 is detected.

On the other hand, when adjusting the balance of the rotating body 16,
The unbalance amount is measured, and the adhesion position and the adhesion amount of the adhesive balance adjusting agent 19 are determined so as to cancel them, and the adhesive balance adjusting agent 19 is adhered (adhered) to the inner peripheral wall surface 17 of the annular wall 18. . Therefore, it is not necessary to machine holes or grooves in order to achieve a dynamic balance of the rotating body 16, no chips are generated and the mirror surface of the rotary polygon mirror 5 is not stained, and the material cost of the magnet member 11 is reduced. Reduction and simple adjustment are possible. Further, since the annular wall 18 is provided on the outermost peripheral portion of the magnet member 11 and provided substantially on the same plane as the center of gravity of the rotating body 16, the radius of the adhesion position of the adhesive balance adjusting agent 19 is increased, and the adhesive balance is adjusted. The adhering portion of the adhesive balance adjusting agent 19 can be made small by minimizing the adhering portion of the agent 19, and the balance adjusting structure of the rotating body can be reduced in cost.

In the present embodiment, the annular wall 18 is provided so as to protrude from the outermost peripheral portion of the upper surface of the magnet member 11, but the annular wall of the present invention is not limited to this, and is shown in, for example, FIGS. It may be formed as follows. In FIG. 3, the yoke 8 and the magnet member 21 are integrated, and the yoke 8
The inner peripheral wall surface 27 of the annular wall 28 is located inward of the outer peripheral surface of the inner wall. In FIG. 4, an annular wall 38 formed on the outer peripheral portion of the magnet member 31 is located on the lower surface side of the magnet member 31 so as to be separated from the rotary polygon mirror 5. However, in this case as well, it is preferable that the position of the center of gravity of the rotating body 16 and the inner peripheral wall surface 37 of the annular wall 38 be substantially at the same position in the axial direction of the rotating body 16. In FIG. 5, the motor magnet unit 42
No recess is formed between the FG magnet portions 43, and the magnet member 41 is flattened to facilitate the formation.

(Effects) According to the present invention, it is possible to easily perform balance adjustment without performing hole processing or groove processing on the rotating body, and it is possible to reduce the material of the magnet part and the adhesive balance adjuster.
As a result, it is possible to provide a low-cost rotating body balance adjustment structure.

[Brief description of the drawings]

1 to 5 are views showing an embodiment of a balance adjusting structure for a rotating body according to the present invention. FIG. 1 is a sectional view of the scanner motor, FIG. 2 is an enlarged sectional view of the magnet part, and FIG. 3
5 to 5 are enlarged cross-sectional views showing other modes of the magnet part. 2 ... rotating shaft, 5 ... rotating polygon mirror, 12, 42 ... motor magnet part, 13, 43 ... FG magnet part, 16 ... rotating body, 17, 27, 37 ... inner peripheral wall surface, 18, 28, 38 …… annular wall,
19 ... Adhesive balance adjuster.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-177334 (JP, A) JP-A-62-164016 (JP, A) JP-A-63-294514 (JP, A) 153517 (JP, U) Japanese Utility Model 62-168771 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02K 15/16

Claims (1)

(57) [Claims] 1. A magnet section having an annular wall formed substantially at the same position as the center of gravity of the rotating body in the direction of the rotation axis of the rotating body on the outer peripheral portion of the rotating body including the rotating polygon mirror provided in the scanner motor. A balance adjustment structure for a rotating body, wherein the balance of the rotating body is adjusted by forming an adhesive balance adjuster on the inner peripheral wall surface of the annular wall of the magnet portion.