JP3383187B2 - Optical deflector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflector having a rotary polygon mirror. More specifically, it relates to a structure for stabilizing the rotation balance in this optical deflector.

[0002]

2. Description of the Related Art An optical deflector used in a laser printer or the like faces a rotor 104 to which a drive magnet 144 is mounted and a drive magnet 144, as disclosed in, for example, Japanese Patent Laid-Open No. 6-284666. The rotary polygon mirror 107 is mounted on a motor main body having an armature core 152 arranged. Rotating polygon mirror 1
A fitting hole 170 is formed at the center of 07, and the cylindrical portion 141 of the rotor 104 is fitted into the fitting hole 17 and is placed on the rotor 104. Further, the rotary polygon mirror 107 has elasticity due to the mirror pressing spring 108 and the spring pressing plate 109.
It is pressed and fixed toward 4. Here, the cylindrical portion 1 of the rotor 104 is inserted into the fitting hole 170 of the rotary polygon mirror 107.
If excessive stress is applied to the rotary polygon mirror 107 when the rotary polygon mirror 107 is fitted, distortion occurs in the rotary polygon mirror 107. Therefore, there is an appropriate distance between the fitting hole 170 of the rotary polygon mirror 107 and the cylindrical portion 141 of the rotor 104. Clear clearance is secured.

In the optical deflector configured as described above, if the weight balance of the entire rotor 104 having the rotary polygon mirror 107 is disturbed, the rotary characteristic of the rotary polygon mirror 107 deteriorates, and accurate optical scanning can be performed. It's gone. Therefore, in the example shown in FIG. 3, the balance correction flange 102 is formed on the rotary polygon mirror 107, and the balance weight 103 is fixed thereto.

[0004]

However, if the balance weight 103 on the balance correction flange 102 is used to correct the weight balance of the entire rotor 104 equipped with the rotary polygon mirror 107, the rotor 104 will rotate at a high speed. In addition, there is a problem that the rotary polygon mirror 107 is displaced on the rotor 104 and the rotational balance is deteriorated. That is, the rotor 1 including the rotary polygon mirror 107
Even if the weight balance of the whole 04 is corrected, if the weight balance of the rotating polygon mirror 107 alone is broken, there is a clearance between the fitting hole 170 of the rotating polygon mirror 104 and the cylindrical portion 141 of the rotor 104. Rotating polygon mirror 1
07 is displaced laterally against the pressing force of the mirror pressing spring 108 on the rotor 104.

In view of the above problems, the object of the present invention is to
By preventing the displacement of the polygon mirror on the rotor,
An object of the present invention is to provide an optical deflector capable of obtaining stable rotation balance.

[0006]

In order to solve the above-mentioned problems, according to the present invention, a rotor having a drive magnet mounted thereon, an armature arranged so as to face the drive magnet, and the rotor is mounted on the rotor. In an optical deflector having a rotating polygon mirror and a clamp means for elastically pressing and fixing the rotating polygon mirror toward the rotor, the rotor comprises:
A rotor balance correction unit for correcting the weight balance as a single said rotor, said rotary polygon mirror has a mirror balance correction unit for correcting the weight balance as a single of the rotary polygon mirror, the mirror balance correction Department is
Formed at a predetermined position in the circumferential direction of the rotary polygon mirror
It is characterized by consisting of holes .

That is, in the present invention, not only the weight balance of the entire rotor having the rotating polygon mirror mounted therein is corrected, but the weight balance of the rotor alone and the weight balance of the rotating polygon mirror alone are individually corrected. It is characterized by being present. Therefore, since the individual weight balances of the rotor and the rotary polygon mirror have been corrected, the weight balance of the entire rotor equipped with the rotary polygon mirror has also been corrected, so that the rotational balance is good. Further, in the present invention, the weight balance of the rotating polygon mirror as a single body is also corrected, so that the rotating polygon mirror does not shift on the rotor even when rotated at high speed. Therefore, the optical deflector to which the present invention is applied can obtain stable rotation balance.

In the present invention, a rotor balance correction unit and
Then, a hole or a balance weight can be used. On the other hand, a hole is formed as the mirror balance correction portion . In this case, it is preferable to form a plurality of the holes on the diagonal line of the upper end surface of the rotary polygon mirror. As described above, when holes are formed on the diagonal line of the rotary polygon mirror, the weight balance of the rotary polygon mirror can be corrected by combining the effect of reducing the weight of each of these holes. Moreover, since it is possible to form a hole at a position away from the outer peripheral surface (mirror surface) of the rotary polygon mirror, there is an advantage that the mirror surface of the rotary polygon mirror is not distorted during the drilling process.

[0009]

DETAILED DESCRIPTION OF THE INVENTION An optical deflector to which the present invention is applied will be described below with reference to the drawings.

[Overall Structure] FIG. 1 is a half sectional view of an optical deflector. Explaining with reference to this figure, the optical deflector 1 of this example
Is a motor frame 2, a fixed shaft 3 mounted on the surface of the motor frame 2 in an upright state, and the fixed shaft 3
The rotor 4 is rotatably supported by the dynamic pressure bearing 6 on the outer periphery of the rotor 4, and the stator 5 is arranged to face the rotor 4. The dynamic pressure bearing 6 is an outer peripheral side surface 3 of the fixed shaft 3.
1 and the first and second dynamic pressure generating grooves 61 and 62 between the shaft hole 411 formed in the rotor 4 and the first hole in the present example.
The second dynamic pressure generating grooves 61 and 62 are formed as herringbone-shaped grooves on the outer peripheral side surface 31 of the fixed shaft 3.

[Structure of Rotor] The rotor 4 has a holder 40 made of aluminum or the like. The holder 40 has a cylindrical portion 41 having the shaft hole 411, and a substantially middle portion of the outer peripheral side surface of the cylindrical portion 41. From the position of the radial direction to the outside in the radial direction, and an annular protruding portion 42, and from the outer peripheral edge of the protruding portion 42 toward the motor frame 2, the axis 1
a cylindrical side surface portion 43 bent perpendicular to the direction of a,
An outer peripheral end portion 46 protruding from the side surface portion 40 to the outer peripheral side is provided.

The projecting portion 42 of the holder 40 is a mounting portion of the rotary polygon mirror 7, in which a cylindrical portion 41 of the holder 40 is fitted into a fitting hole 70 formed at the center of the rotary polygon mirror 7.
And the rotary polygon mirror 7 is placed on the overhanging portion 42. In this state, the rotary polygon mirror 7 has the mirror pressing spring 8
It is elastically pressed and fixed toward the overhanging portion 42 by the clamping means including the cap 9. Here, if excessive stress is applied to the rotary polygon mirror 7 when the cylindrical portion 41 of the rotor 40 is fitted into the fitting hole 70 of the rotary polygon mirror 7, the rotary polygon mirror 7 is distorted. An appropriate clearance is provided between the fitting hole 70 and the cylindrical portion 41 of the rotor 40, and the positional displacement of the rotary polygon mirror 7 caused by such clearance is suppressed by the mirror pressing spring 8.

[Arrangement of Armature and Its Surroundings] Holder 4
On the outer peripheral side of the cylindrical portion 41 of 0, the stator 5 is provided below the protruding portion 42 so as to concentrically surround the cylindrical portion 41. The stator 5 includes a substantially cylindrical core holder 51, and the lower end of the core holder 51 is fixed to the upper surface of the motor frame 2. The stator core 52 is attached to the outer peripheral side surface on the upper end side of the hole holder 51 by utilizing the step portion. This stator core 5
In FIG. 2, the stator coil 53 is wound around a plurality of salient poles formed at regular intervals in the radial direction to form the armature 50. On the other hand, the rotor 4 is
An annular drive magnet 44 is arranged so as to concentrically surround the outer circumference of the stator core 52, and the drive magnet 44 is formed on the holder 40 of the rotor 4 by the side surface portion 4.
3 is fixed to the inner peripheral side surface of the magnet yoke 45 fixed to the inner peripheral side surface. The motor board 12 is arranged on the upper surface of the motor frame 2 below the stator core 52 and the drive magnet 44, and electronic parts such as the connector 13 are mounted on the upper and lower surfaces of the board 12.

On the tip side of the fixed shaft 3, a circular concave portion 32 is formed at the tip portion thereof, and an annular stator magnet 14 is fixed to the inner peripheral side surface of the concave portion 32.
Inside the stator magnet 14, an annular rotor magnet 15 fixed to the cap 9 is arranged. Here, the magnetic center in the direction of the axis 1a of the rotor magnet 15 is the axis 1a of the stator magnet 14.
The magnetic center is slightly deviated from the magnetic center in the direction of the axis 1a toward the fixed shaft 3 side. Further, since the same poles of the stator magnet 14 and the rotor magnet 15 face each other, the thrust bearing is constituted by the magnetic repulsive force generated between them, and there is rattling in the direction of the motor axis 1a. The occurrence is suppressed.

[Structure for Correcting Weight Balance] In the optical deflector 1 of this example, the rotor 4 equipped with the rotary polygon mirror 7 is mounted.
It is characterized in that not only the entire weight balance is corrected, but also the weight balance of the rotor 4 as a single body and the weight balance of the rotating polygon mirror 7 as a single body are individually corrected.

That is, in this example, first, the rotary polygon mirror 7
Of the rotating polygon mirror 7 as shown in FIG. 1 and FIG. 2 based on the inspection result.
The weight balance of the rotary polygon mirror 7 is corrected by forming a hole 79 (mirror balance correction portion) in the upper end surface of the and reducing the weight.

In correcting the weight balance of the rotary polygon mirror 7 in this way, as shown by the dotted line in FIG.
One hole 79 may be formed at an optimum position of the rotary polygon mirror 7. However, when the position where the hole 79 is formed is near the outer peripheral surface (mirror surface 71) of the rotary polygonal mirror 7, the mirror surface 71 of the rotary polygonal mirror 7 may be distorted during the drilling process.

Therefore, in the present embodiment, a plurality of holes 79 are formed on the diagonal line 72 (shown by the one-dot chain line in FIG. 2) of the rotary polygon mirror 7, and the effect of reducing the weight of each of the holes 79 is combined. The weight balance of the rotary polygon mirror 7 is corrected. As described above, if the hole 92 is formed on the diagonal 72 of the rotary polygon mirror 7, the hole can be formed at a position away from the outer peripheral surface (mirror surface 71) of the rotary polygon mirror 7. The mirror surface 71 of the polygon mirror 7 is not distorted.

Next, the weight balance of the rotor 4 as a single body is corrected. To make this correction, the rotor 4
The weight balance as a single body is inspected, and based on the inspection result, as shown in FIGS. 1 and 2, a hole 49 is made in the upper end surface of the outer peripheral end portion 46 of the holder 40 of the rotor 4 to reduce the weight of this portion. The weight balance of the rotor 4 is corrected by the conversion. Further, since the weight balance of the rotary polygon mirror 7 as a single body has already been corrected by the above method, the weight balance of the entire rotor 4 including the rotary polygon mirror 7 is inspected, and based on this inspection result, If a hole 49 is made in the upper end surface of the outer peripheral end portion 46 of the holder 40 of the rotor 4 to reduce the weight of this portion, the weight balance of the rotor 4 as a single body is corrected as a result.

In this way, if the weight balance of the rotor 4 alone and the weight balance of the rotary polygon mirror 7 are individually corrected, the weight balance of the entire rotor 4 having the rotary polygon mirror 7 mounted thereon can be improved. Since it has been corrected, the rotation balance of the optical deflector 1 is good. Moreover, since the weight balance of the rotary polygon mirror 7 as a single unit is also corrected, the rotary polygon mirror 7 has a good rotary balance as a single unit.
Therefore, even if the rotor 4 rotates at high speed, the rotary polygon mirror 7
A good rotational balance can be maintained without causing positional displacement on the rotor 4 due to vibration or centrifugal force at that time.

[Other Embodiments] In the above embodiment, in correcting the weight balance of the rotor 4 alone and the weight balance of the rotary polygon mirror 7 alone, the rotary polygon mirror 7 and the rotor 4 ( By opening holes 79 and 49 in the holder 40),
Although this part was lighter, the rotor 4 (holder 40) Nitsu
Then, by fixing a balance weight made of iron or the like, which is heavier than aluminum used to form the rotor 4, and making the portion to which the balance weight is fixed heavy,
Weight balance may be modified. Also, rotor balance
Of course , a hole and a balance weight may be used together as the correction portion . For example, if a balance weight is arranged in the hole so that useless unevenness is not formed on the rotor , the rotor will not use air. There is no resistance.

[0022]

As described above, the optical deflector according to the present invention is characterized in that the weight balance of the rotor alone and the weight balance of the rotary polygon mirror alone are individually corrected. Therefore, the weight balance of the entire rotor equipped with the rotary polygon mirror is corrected, and the rotation balance of the optical deflector is good. Moreover, since the weight balance of the rotating polygon mirror as a single unit is also corrected, the rotating polygon mirror has a good rotation balance as a single unit. Therefore,
Even if the rotor rotates at high speed, the rotating polygon mirror does not cause displacement on the rotor due to vibration or centrifugal force at that time.
Good rotation balance can be maintained.

[Brief description of drawings]

FIG. 1 is a half sectional view showing a schematic configuration of an optical deflector to which the present invention is applied.

FIG. 2 is a plan view of a rotary polygon mirror and a rotor in the optical deflector shown in FIG.

FIG. 3 is a half sectional view showing a schematic configuration of a conventional optical deflector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical deflector 3 Fixed shaft 4 Rotor 6 Dynamic pressure bearing 7 Rotating polygon mirror 8 Mirror holding spring 9 used for clamp means 9 Cap used for clamp means 11 Stator 40 Holder 41 Cylindrical part 49 Hole for weight balance correction (rotor balance Correction part 50 Armatures 61, 62 Dynamic pressure generation groove 70 Fitting hole 71 Mirror surface 72 Diagonal line 79 of rotary polygon mirror Weight correction hole (mirror balance correction part)

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Claims (2)

(57) [Claims] 1. A rotor on which a drive magnet is mounted,
In an optical deflector having an armature arranged opposite to the drive magnet, a rotary polygon mirror mounted on the rotor, and a clamp means for elastically pressing and fixing the rotary polygon mirror toward the rotor, The rotor includes a rotor balance correction unit that corrects the weight balance of the rotor alone, and the rotary polygon mirror includes a mirror balance correction unit that corrects the weight balance of the rotary polygon mirror alone . The mirror balance correction unit is arranged in the circumferential direction of the rotary polygon mirror.
An optical deflector characterized by comprising a hole formed at a predetermined position in . 2. The mirror balance according to claim 1,
The hole that constitutes the correction portion is formed on the upper end surface of the rotary polygon mirror.
An optical deflector characterized in that a plurality of them are formed on a diagonal line .