JPH11249059A - Optical deflecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the high-performance, inexpensive optical deflecting device capable of easily correcting the balance of a rotary polygon mirror with the reduced number of processes and evading trouble such as variance in precision in such a case that a balance weight, etc., is added. SOLUTION: The rotary polygon mirror 1 is supported on the top surface of a flange member 4 and rotates together with a rotary shaft 3. On the reverse surface of the flange member 4, the rotor 5 of a motor is fixed and faces the stator 7. The flange member 4 is formed of a metallic material which contains A1, brass, etc., and has good machinability and its outer peripheral part projects radially from the circumscribed circle of the rotary polygon mirror 1. The surface, etc., of this projection part 4a is ground to correct the balance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light deflecting device used for an image forming apparatus such as a laser beam printer and a laser facsimile.

[0002]

2. Description of the Related Art A light deflecting device used in an image forming apparatus such as a laser beam printer or a laser facsimile machine uses a rotating polygon mirror which rotates at a high speed to form a laser beam (laser light).
And the like, and deflects and scans the light beam to form an electrostatic latent image by forming the obtained scanning light on a photosensitive member on a rotating drum. Next, the electrostatic latent image on the photoreceptor is visualized into a toner image by a developing device, transferred to a recording medium such as recording paper, sent to a fixing device, and printed by heating and fixing the toner on the recording medium ( Print) is performed.

In recent years, the speed of an optical deflector has been increased, and it has been desired to further increase the speed and improve the rotational performance of a rotary polygon mirror.

FIG. 5 shows a main part of an optical deflector according to a conventional example disclosed in Japanese Patent Application Laid-Open No. 8-182287, which is rotatably supported in a non-contact manner by a sleeve 102 constituting a fluid bearing. The rotating shaft 103, the rotor frame 105a and the rotor magnet 105b coupled to the flange member (mirror mounting member) 104 integrated with the rotating shaft 103, and the stator fixed to the base plate 106 integrated with the sleeve 102 Coil 107
Having. The rotating polygon mirror 101 is pressed against the flange member 104 by a holding plate 108 or the like, and
4 and is integrated with the rotating shaft 103 and the rotor magnet 105b.

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

When the rotating polygon mirror 101 is rotated at a high speed, a dynamic imbalance occurs due to an imbalance in the mass of the entire rotating body _R0 including the rotating polygon mirror 101, the flange member 104, the rotor frame 105a, the rotor magnet 105b, and the like. The image quality of the image forming apparatus may be degraded due to the generated whirling vibration and the like. Therefore, a weight mounting portion (recess) 1 is provided on the outer peripheral portion of the rotor frame 105a.
05c and a weight (balance weight) 109
Are bonded to reduce the imbalance of the mass of the rotating body _R0 .

The weight 109 is made by mixing metal particles, glass beads, or the like with a light-curing adhesive such as an ultraviolet-curing type, and an appropriate amount of the weight 109 is applied to an appropriate portion of the weight mounting portion 105c of the rotor frame 105a. And cured by irradiating light such as ultraviolet rays.

[0008] Weight mounting portion 10 of rotor frame 105a
5c is opposed to a retaining member 110 erected on the base plate 106, and the rotating body _R0 is
Together with the axial direction, the retaining member 110 engages with the outer peripheral edge of the weight mounting portion 105c of the rotor frame 105a to suppress the movement of the rotating body _R0 , thereby causing an accident such as the rotating shaft 103 coming out of the sleeve 102. It is configured to prevent.

[0009]

However, according to the above prior art, a weight mounting portion (recess) is provided on the rotor frame.
And the balance weight is adhered to this, so that there are the following unsolved problems.

(1) Since the adhesive strength of the balance weight changes depending on the surface roughness of the rotor frame, the strength of the balance weight varies.

(2) When the amount of the balance weight increases, there is a possibility that the balance weight may interfere with the retaining member.

(3) Since the balance weight is mainly composed of an adhesive, a balance correction step is required, for example, the weight applied to the weight mounting portion varies, and a step of curing the adhesive is required. It is complicated and has many steps.

(4) Since the material of the rotor frame is generally an iron-based material, rust and the like are generated when the rotor frame is cut to correct the balance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and the balance of a rotary polygon mirror can be easily corrected and the number of processes can be reduced. In addition, a balance weight or the like is added. It is an object of the present invention to provide a high-performance and inexpensive optical deflecting device that can avoid troubles such as variation in accuracy as in the case of the above.

[0015]

In order to achieve the above object, an optical deflecting device according to the present invention comprises: a rotating polygon mirror for deflecting and scanning a light beam; a rotating polygon mirror supporting member for supporting the rotating polygon mirror; A motor comprising a rotor and a stator opposed thereto, which is integral with the rotary polygon mirror support member, wherein the rotary polygon mirror support member has a protrusion projecting radially outward from an outer diameter portion of the rotary polygon mirror. And at least a part of the protrusion is made of a material having excellent workability.

The entire rotary polygon mirror support member may be made of a material having excellent workability.

It is preferable that a protruding portion of the rotary polygon mirror support member is provided with a cutout for correcting the balance.

[0018]

The outer peripheral portion of a rotating polygon mirror supporting member such as a flange member for supporting the rotating polygon mirror is projected radially outward from the outer diameter portion of the rotating polygon mirror. A metal material containing Al, Zn, or brass, which has good laser workability, is used. Instead of adding a balance weight to the outer periphery of the rotor frame, etc., select the appropriate part of the protruding part of the rotating polygon mirror support member with excellent workability and cut off an appropriate amount to balance the rotating polygon mirror. Make corrections.

Compared with the case where a balance weight or the like is added, the process of correcting the balance is simpler, and problems such as variations in accuracy and interference of the balance weight with peripheral components can be avoided.

As a result, the manufacturing cost of the optical deflector can be significantly reduced, and the balance correction accuracy and the like can be greatly improved, thereby contributing to higher performance of the optical deflector.

[0021]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing a main part of an optical deflecting device according to a first embodiment, which is a rotary polygon mirror 1 having a plurality of reflecting surfaces 1a on a polygonal prism-shaped side surface and a later-described mirror. Sleeve 2, which is a fluid bearing supported by a bearing housing integral with an optical box 50, a rotating shaft 3 rotatably supported by the sleeve 2, and a rotating polygon mirror support member fixed to the rotating shaft 3. , A rotor frame 5a integrally joined to the lower surface thereof, and a stator coil 7a fixed to a base plate 6 integrated with the bearing housing. The stator coil 7a
It is wound around a stator core 7b on which magnetic steel sheets are laminated, and is disposed to face the rotor magnet 5b supported on the inner peripheral surface of the rotor frame 5a. The rotor 5 composed of the rotor frame 5a and the rotor magnet 5b constitutes a motor for rotatingly driving the rotary polygon mirror 1 together with the stator 7 composed of the stator coil 7a and the stator core 7b.

The rotary polygon mirror 1 is pressed against the flange member 4 by the holding plate 8, and is integrated with a rotating portion including the flange member 4, the rotor frame 5a, the rotor magnet 5b and the like.

When the stator coil 7a is excited by a drive current supplied through a drive circuit and a control circuit on the base plate 6, the rotor 5 rotates together with the rotating shaft 3 and the rotating polygon mirror 1, and the rotating polygon mirror 1 The light beam such as a laser beam applied to the reflection surface 1a is deflected and scanned.

The sleeve 2 is made of a material having excellent wear resistance, such as a ceramic material, and at least one of the sleeve 2 and the rotating shaft 3 is provided with a herringbone-shaped shallow groove. A dynamic pressure of the lubricating fluid is generated between the sleeve 2 and the rotating shaft 3 to rotate and support the rotating shaft 3 in a non-contact manner.

[0026] rotating the rotary polygon mirror 1 at a high speed, the rotary polygon mirror 1, the flange member 4, the rotor frame 5a, generating a whirling vibration by dynamic unbalance of the rotating body R ₁ consisting of the rotor magnet 5b etc. However, for this reason, the image quality of the image forming apparatus may be degraded.

Therefore, the outer diameter portion of the flange member 4 is projected radially outward from the circumscribed circle (outer peripheral portion) of the rotary polygon mirror 1,
As shown in FIG. 2, an annular protrusion 4a is formed, and the balance is corrected by locally shaving the upper surface or the like by a known method such as cutting. As the material of the flange member 4, a material such as a metal material containing Al or brass, which is easy to cut and has excellent workability which does not cause significant rust or the like even when cut, is selected. deep. When an iron-based material is used as in the conventional example, the cut portion (cut portion) is significantly rusted, the balance is fluctuated, and rust powder is scattered and adheres to the reflection surface 1a of the rotary polygon mirror 1. Causes trouble.

[0028] be previously based on the mass distribution of the flange member 4 and the like for data required cutting depth or the like of the flange member 4 for balance correction, based on the measured values or the like of the dynamic imbalance of the rotating body R ₁ The cutting amount of the flange member 4 and its position can be selected quickly and the balance correction with extremely high precision can be easily performed.

In the process of correcting the balance, it is only necessary to locally cut the upper surface and the like of the flange member 4 by a method such as cutting.
It is necessary to provide a process to cure the adhesive after attaching the balance weight, as in the case of using a balance weight mainly composed of adhesive, the amount of balance weight added varies, and the balance correction amount becomes inaccurate. There is no. Therefore, the accuracy of the balance correction is high, the operation is simple, and the number of steps is small, which greatly contributes to the reduction of the manufacturing cost and the high performance of the optical deflecting device.

In addition, since only the upper surface of the flange member 4 is slightly cut, a wind noise or the like is generated at the time of rotation as in the case where a balance weight is added, and other components such as the retaining member 10 are prevented. There is a remarkable advantage that projections that may interfere with the structure are not generated.

FIG. 3 is a schematic sectional view showing an optical deflecting device according to the second embodiment. This is obtained by integrating a ring member 14a for correcting the balance with an outer peripheral portion (projection) of the same flange member 14 as the flange member 4 of FIG. 1 by a known method such as shrink fitting. The ring member 14a is made of Al
Alternatively, it is made of a material that is easy to cut, such as a metal material containing brass, and whose cut portion is hard to rust. As in the first embodiment, the balance correction step is performed by selecting a part necessary for the balance correction and shaving the ring member 14a by a required amount.

The rotary polygon mirror 1, the sleeve 2, the rotary shaft 3, the rotor frame 5a, the rotor magnet 5b, the stator coil 7a, the stator core 7b and the like are the same as those in the first embodiment, and are represented by the same reference numerals. Omitted.

According to the present embodiment, the material of the remaining portion (base material) of the flange member is limited only by limiting the material of the ring member for correcting the balance to a material that is excellent in workability such as machinability and is resistant to rust. Has the advantage of being freely selectable.
In other words, by arbitrarily selecting the material of the ring member in accordance with the processing method for balance correction, simplification of the balance correction process can be further promoted.

For example, when the balance is corrected by laser processing, the ring member is made of a material that does not easily reflect laser light, for example, a metal material containing brass, Zn, or the like. Further, when a more precise and delicate balance correction is required, a material having a low specific gravity can be used as the material of the ring member. Conversely, when performing a rough balance correction with a large ballast correction amount, a ring member made of a heavy material can be used.

As described above, there is an advantage that the accuracy of balance correction can be freely set.

FIG. 4 shows the entire light deflecting device, which includes a light source 51 for generating a light beam L ₁ such as a laser beam, and the like.
And a cylindrical lens 51a for condensing the light beam L ₁ into a linear shape on the reflecting surface 1a of the rotary polygon mirror 1, the light beam L ₁ is deflected and scanned by the rotation of the rotary polygon mirror 1, the imaging lens system 52 And form an image on the photoreceptor 53 on the rotating drum. The imaging lens system 52 includes a spherical lens 52a, a toric lens 52b, and the like, and has a so-called fθ function of correcting a scanning speed and the like of a point image formed on the photoconductor 53.

When the rotary polygon mirror 1 is rotated by the motor, its reflection surface 1a rotates at a constant speed around the axis of the rotary polygon mirror 1. Generated from the light source 51 as described above,
Normal and the angle of the reflecting surface 1a of the cylindrical lens 51a optical path and the rotary polygon mirror 1 of the light beam L ₁ is condensed by, that the angle of incidence of the light beam L ₁ with respect to the reflecting surface 1a is the rotary polygon mirror 1 Changes over time with the rotation of
Similarly, since the reflection angle also changes, the point image formed by condensing the light beam on the photoconductor 53 moves in the main scanning direction.

The imaging lens system 52 condenses the light beam (scanning light) reflected by the rotary polygon mirror 1 on the photosensitive member 53 into a point image having a predetermined spot shape, and in the main scanning direction of the point image. It is designed to keep the scanning speed at constant speed.

The point image formed on the photoreceptor 53 is electrostatically generated by the main scanning by the rotation of the rotary polygon mirror 1 and the sub-scanning by the rotation of the rotating drum having the photoreceptor 53 around its axis. Form a latent image.

A charging device is provided around the photosensitive member 53 to uniformly charge the surface of the photosensitive member 53 and an electrostatic latent image formed on the surface of the photosensitive member 53 is visualized as a toner image. a developing device, the are arranged transfer device or the like onto a recording sheet or the like of the toner image, the recording information by the light beam L ₁ generated from the light source 51 is printed on the recording paper.

The detection mirror 54 reflects the light beam on the upstream side in the main scanning direction with respect to the optical path of the light beam incident on the photosensitive member 53 at the position where the recording information is started to be written. Into the light-receiving surface of the light-receiving element 56. The light receiving element 56 outputs a write start signal for controlling a write start position (write start position) when the light receiving surface is irradiated with the light beam.

The light source 51 generates a light beam corresponding to a signal given from a processing circuit for processing information from a host computer. The signal given to the light source 51 corresponds to information to be written on the photoconductor 53, and the processing circuit represents information corresponding to one scanning line which is a locus formed by a point image formed on the surface of the photoconductor 53. The signal is given to the light source 51 as one unit. This information signal is transmitted in synchronization with a write start signal given from the light receiving element 56.

The rotary polygon mirror 1, the imaging lens system 52 and the like are housed in an optical box 50, and the light source 51 and the like are mounted on the side wall of the optical box 50. After the rotating polygon mirror 1, the imaging lens 52 system, and the like are assembled in the optical box 50, a lid (not shown) is attached to the upper opening of the optical box 50.

[0044]

Since the present invention is configured as described above, the following effects can be obtained.

The balance of the rotary polygon mirror can be easily corrected and the number of processes can be reduced. In addition, there is no trouble such as variation in accuracy as in the case of adding a balance weight or the like. This can greatly contribute to higher performance and lower cost of the optical deflection device.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a main part of an optical deflecting device according to a first embodiment.

FIG. 2 is a plan view showing the apparatus of FIG.

FIG. 3 is a schematic sectional view showing a main part of an optical deflecting device according to a second embodiment.

FIG. 4 is a diagram illustrating the entire light deflection device.

FIG. 5 is a schematic cross-sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating polygon mirror 2 Sleeve 3 Rotating shaft 4, 14 Flange member 4a Projection part 5 Rotor 5a Rotor frame 5b Rotor magnet 7 Stator 7a Stator coil 7b Stator core 10 Retaining member 14a Ring member

Claims (5)

[Claims] A rotary polygon mirror for deflecting and scanning a light beam;
A rotating polygon mirror supporting member for supporting the rotating polygon mirror, a motor integrated with a rotor integrated with the rotating polygon mirror supporting member and a stator opposed thereto, wherein the rotating polygon mirror supporting member includes the rotating polygon mirror; An optical deflecting device comprising: a protruding portion that protrudes radially outward from an outer diameter portion of (a), wherein at least a part of the protruding portion is made of a material having excellent workability. 2. The optical deflecting device according to claim 1, wherein the entire rotary polygon mirror support member is made of a material having excellent workability. 3. The optical deflecting device according to claim 1, wherein at least a part of the projection of the rotary polygon mirror support member is made of a metal material containing Al or brass. 4. The optical deflecting device according to claim 1, wherein at least a part of the protrusion of the rotary polygon mirror support member is made of a metal material containing Zn. 5. An optical deflecting device according to claim 1, wherein a cutout portion for correcting the balance is provided on the projecting portion of the rotary polygon mirror supporting member.