JP3402897B2 - Deflection scanning device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection scanning device used in an image forming apparatus such as a laser beam printer or a laser facsimile.

[0002]

2. Description of the Related Art FIG. 6 illustrates a general deflection scanning device used in an image forming apparatus such as a laser beam printer or a laser facsimile, which comprises a light source unit 50 for generating a laser beam and the laser beam. Rotating polygon mirror 1
01 has a cylindrical lens 51 for linearly condensing on the reflecting surface 101a of No. 01.
The image is deflected and scanned by the rotation of 1, and the image is reflected on the image forming lens system 52 and passed through the mirror 53 to form an image on a photoconductor on a rotating drum (not shown). The imaging lens system 52 is a spherical lens 52.
a, a toric lens 52b, etc., and has a function of correcting the distortion of the point image formed on the photoconductor. Also,
A part of the deflected and scanned laser light is introduced into the light receiving end of the optical fiber by a reflection mirror (not shown), converted into a scanning start signal, and then the semiconductor laser 50a of the light source unit 50.
Sent to.

Around the photoconductor, a corona discharger for uniformly charging the surface of the photoconductor, and a visualization device for visualizing an electrostatic latent image formed on the surface of the photoconductor into a toner image. A transfer corona discharger (not shown) for transferring the toner image to the recording paper is arranged, and by these functions, recording information corresponding to the modulation of the semiconductor laser 50a is printed on the recording paper.

Further, the irradiation position of the deflection scanning device is adjusted by positioning pins 55 and 56 provided outside the optical box 54.
It is done by. That is, the positioning pin 5
Reference numerals 5 and 56 engage with the respective guide holes 55a and 56a, and the irradiation position of the optical box 54 in the X direction (optical axis direction) is adjusted by moving both the positioning pins 55 and 56 in the same direction in the X direction. The adjustment of the θ direction (rotation angle) of the optical box 54 is performed by moving the positioning pin 55 and the positioning pin 56 in opposite directions in the X direction.

In recent years, the speed of the deflection scanning device has been increased, and a rotary polygon mirror 101 whose rotational speed exceeds 10,000 rpm has been developed.

The drive unit for rotating the rotary polygon mirror 101 is
As shown in FIG. 5, a rotating shaft 103 supported by the optical box 54 via a ball bearing 102 and a yoke 105a integrally connected to a washer 104 which is integral with the rotating shaft 103.
And the rotor magnet 105 and the bearing housing 1
02a has a stator coil 107 fixed to a motor substrate 106, and the rotary polygon mirror 101 is pressed against a washer 104 by an elastic pressing mechanism 108 including a pressing spring 108a, a spring presser 108b, etc.
It is integrated with the rotor magnet 105.

When the stator coil 107 is excited by the drive current supplied from the drive circuit on the motor board 106, the rotor magnet 105 rotates at a high speed together with the rotary polygon mirror 101, and as described above, the rotary polygon mirror 101.
The laser light applied to the laser is deflected and scanned.

When the rotary polygon mirror 101 is rotated at a high speed, a dynamic imbalance due to the unbalance of the mass of the entire rotary body including the rotary polygon mirror 101, the rotor magnet 105, the yoke 105a, the washer 104 and the elastic pressing mechanism 108 is generated. Whirling vibration or the like is generated due to the balance, which may deteriorate the image quality of the image forming apparatus. Therefore, an annular balance groove 109 is provided in the yoke 105a of the rotor magnet 105, and a weight 110 is bonded to the annular balance groove 109 to eliminate the unbalance of the mass of the rotating body.

The weight 110 is a mixture of metal particles, glass beads and the like in a photo-curable adhesive such as an ultraviolet curable adhesive, and an appropriate amount of the weight 110 is placed on an appropriate portion of the balance groove 109. It is cured by being irradiated with light such as ultraviolet rays and adhered to the balance groove 109.

[0010]

However, according to the above-mentioned conventional technique, when the outer diameter of the rotary polygon mirror is larger than the outer diameter of the yoke of the rotor magnet, the rotary polygon mirror becomes an obstacle. It is extremely difficult to attach a weight to the balance groove of the rotor magnet yoke, and even if a weight can be attached to the balance groove of the rotor magnet yoke, it will still rotate when irradiated with light such as ultraviolet rays. The polygon mirror becomes an obstacle, light does not reach the bottom of the balance groove sufficiently, the adhesive is insufficiently cured, and the curing time becomes long.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and provides a deflection scanning device in which a weight for preventing vibration of a rotary polygon mirror is extremely easy to attach. The purpose is.

[0012]

To achieve the above object, a deflection scanning device of the present invention comprises a rotary polygon mirror for deflecting and scanning a light beam, and a first magnetic member which is rotatable integrally with the rotary polygon mirror. And a second magnetic member that constitutes a drive unit that rotates the rotary polygon mirror together with the first magnetic member, and a balance groove is provided on an outer peripheral portion of the first magnetic member. It is characterized in that the outer peripheral wall of the groove is inclined radially outward by a predetermined inclination angle with respect to the central axis of the rotary polygon mirror.

[0013]

By attaching an appropriate amount of weight to an appropriate portion of the balance groove of the first magnetic member, whirling vibration of the rotary polygon mirror is prevented. Since the outer peripheral wall of the balance groove is inclined radially outward with respect to the central axis of the rotary polygon mirror, the outer diameter of the rotary polygon mirror is smaller than the outer diameter of the first magnetic member. Even if the weight is attached, it is easy. Also, when curing the adhesive contained in the weight by light,
Since the light can be sufficiently irradiated to the bottom of the balance groove, the adhesive can be sufficiently cured in a short time. As a result, the assembly process of the device can be greatly simplified.

As a result, downsizing and cost reduction of the deflection scanning device can be promoted.

When the inclination angle of the outer peripheral wall of the balance groove is 90 degrees, workability is further improved, and stress concentration due to centrifugal force applied to the outer peripheral wall when the rotary polygon mirror is rotated is prevented, and the centrifugal force is generated. It is possible to avoid damage to the magnetic member.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic partial sectional view showing the main part of the deflection scanning device according to the first embodiment, in which a laser beam, which is a light beam generated from a light source unit (not shown), is passed through an imaging lens system. A rotary polygonal mirror 1 having a polygonal prism-shaped reflecting surface that deflects and scans toward a direction, a rotary shaft 3 supported by a ball bearing 2 in an optical box (not shown), and a rotary shaft 3 through a washer 4 integrated with the rotary shaft 3. The rotary polygon mirror 1 includes a rotor 5 which is a first magnetic member integrally connected with the rotor 5 and a stator 7 which is a second magnetic member fixed to the motor substrate 6 and constitutes a drive unit together with the rotor 5. Presser spring 8
Is pressed by the washer 4 and integrated with the rotating shaft 3 and the rotor 5.

When the stator 7 is excited by the drive current supplied from the drive circuit on the motor board 6, the rotor 5
Rotates together with the rotary shaft 3 and the rotary polygon mirror 1, and deflects and scans the laser light emitted to the rotary polygon mirror 1 as described above.

When the rotary polygon mirror 1 is rotated at a high speed, whirling vibrations and the like are generated due to dynamic imbalance of the rotating body composed of the rotary polygon mirror 1, the washer 4, the rotor 5 and the like.
The image quality of the image forming apparatus may deteriorate. Therefore,
An annular balance groove 9 is provided on the outer peripheral portion of the rotor 5, and a weight 10 is adhered to the groove to reduce the unbalance of the mass of the rotating body. The weight 10 is obtained by mixing metal particles, glass beads, or the like into a photo-curing adhesive such as an ultraviolet curable adhesive, and rotating the rotary polygon mirror 1 to measure its whirling vibrations and the like, and measure the measured value. Based on this, the weight and the mounting position of the weight 10 are selected.

In this embodiment, the outer diameter of the rotor 5 is set smaller than the outer diameter of the rotary polygon mirror 1 in order to reduce the size of the deflection scanning apparatus as a whole.
It is difficult to add the weight 10 from above in the figure, and it is difficult to allow the light to reach the bottom of the balance groove 9 because the direction of irradiating the light for curing the adhesive of the weight 10 is limited. The agent cannot be cured sufficiently. Therefore, the balance groove 9 is opened toward the side of the rotor 5 by inclining the outer peripheral wall 9a of the balance groove 9 radially outward by a predetermined inclination angle θ.

The inclination angle θ of the outer peripheral wall 9a of the balance groove 9
Is an angle θ formed by the inclined surface extending from the maximum outer diameter portion of the rotary polygon mirror 1 toward the bottom of the balance groove 9 and the central axis O of the rotary polygon mirror 1.
_It is desirable to be in the range of ₀ to 90 °.

By thus opening the balance groove 9 toward the side of the rotor 5, the rotary polygon mirror 1 becomes an obstacle in the work of adding the weight 10 by the injector T or the like, or the adhesive of the weight 10 is applied. It is possible to avoid the inconvenience that the light for curing the light is blocked by the rotary polygon mirror 1. That is, in the deflection scanning device having a smaller drive unit, the process of attaching the weight 10 to the balance groove 9 can be significantly simplified and speeded up, which can greatly contribute to the downsizing of the deflection scanning device and the reduction of the manufacturing cost.

FIG. 2 shows a case where the inclination angle θ of the outer peripheral wall 19a of the balance groove 19 is 90 °. This is the same as the one in which a flange portion outward in the radial direction is provided at the lower end of the rotor 15, and the corner portion 15a of the flange portion constitutes the balance groove 19. Thus, if the inclination angle θ of the outer peripheral wall 19a of the balance groove 19 is 90 °, (1) the outer shape of the rotor 15 can be made extremely simple and the manufacturing cost can be reduced. (2) The rotor 15 can be made of resin. in the case of,
Formability is improved because the wall thickness can be made uniform, (3) The degree of freedom in the direction of light for curing the weight 10 is increased, and workability is improved. (4) Rotation of the rotary polygon mirror 1 causes the rotor 15 There is an advantage that the stress that occurs can be reduced.
Explaining (4), as shown in FIG. 3, when the inclination angle θ of the outer peripheral wall 9a of the balance groove 9 is 90 ° or less, the outer peripheral wall 9a of the balance groove 9 is rotated when the rotor 5 rotates together with the rotary polygon mirror 1. The lower end of the rotor 5 is deformed as shown by the broken line due to the centrifugal force acting on, and a large stress is locally generated at the lower end of the inner diameter portion. However, as shown in FIG. 4, when the inclination angle θ of the outer peripheral wall 19a of the balance groove 19 is 90 °, the centrifugal force acting on the outer peripheral wall 19a becomes small, so that the above stress concentration does not occur.

[0024]

Since the present invention is configured as described above, it has the following effects.

It is easy to attach a weight to prevent whirling vibration of the rotary polygon mirror, and light for curing the adhesive contained in the weight reaches the bottom of the balance groove to shorten the adhesive. It can be cured sufficiently in time. This simplifies the assembly process of the deflection scanning device,
It is possible to promote downsizing and cost reduction of the deflection scanning device.

[Brief description of drawings]

FIG. 1 is a schematic partial sectional view showing a main part of a deflection scanning device according to an embodiment.

FIG. 2 is a schematic partial sectional view showing a main part of a deflection scanning device according to a modification.

FIG. 3 is a diagram for explaining the stress generated in the rotor in the device of FIG.

FIG. 4 is a diagram for explaining the stress generated in the rotor in the device of FIG.

FIG. 5 is a schematic partial cross-sectional view showing a main part of a deflection scanning device according to a conventional example.

FIG. 6 is a plan view showing the entire deflection scanning device of FIG.

[Explanation of symbols]

1 rotating polygon mirror 3 rotation axes 5,15 rotor 7 Stator 9,19 Balance groove 10 weights

Claims (4)

(57) [Claims] 1. A rotating polygon mirror for deflecting and scanning a light beam,
A first magnetic member that is rotatable integrally with the first magnetic member and a second magnetic member that constitutes a drive unit that rotates the rotary polygon mirror together with the first magnetic member, and the first magnetic member. A deflection groove is provided in an outer peripheral portion of the rotary groove, and an outer peripheral wall of the balance groove is inclined radially outward by a predetermined inclination angle with respect to a central axis of the rotary polygon mirror. apparatus. 2. The deflection scanning device according to claim 1, wherein the tilt angle is 90 degrees or less. 3. The deflection scanning device according to claim 1, wherein the tilt angle is 90 degrees. 4. The outer diameter of the first magnetic member is smaller than the outer diameter of the rotary polygon mirror.
The deflection scanning device according to claim 1.