JPH11258537A - Light deflection scanning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dust from entering into a rolling bearing which rotates/ supports a rotary polygon mirror. SOLUTION: A rotary polygon mirror 1 is rotationally driven by a motor constituted of a rotor magnet 4 and a stator coil 6. A rolling bearing 2 which supports a rotary shaft 3 so that it can freely turn holds a ball string 23 in a bearing gap between an outer ring 22 which is integrated with a sleeve 21 and the rotary shaft 3. A sealing member 27 for preventing dust from entering into the bearing gap is integrally provided with the rotary shaft 3. Thus, abrasion powder dropping along the rotary shaft 3 is prevented from entering into the bearing gap at the time of fixing the rotor magnet 4 to the rotary shaft 3 by force-fitting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light deflection scanning 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 deflection scanning device used in an image forming apparatus such as a laser beam printer or a laser facsimile is
A light beam such as a laser beam is deflected and scanned by a rotating polygon mirror that rotates at a high speed, and the obtained scanning light is focused on a photosensitive member on a rotating drum to form an electrostatic latent image. 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 deflection scanning device has been increased,
A rotating polygon mirror whose rotation speed exceeds 10,000 rpm has also been developed.

FIG. 6 shows a main part of an optical deflection scanning apparatus according to a conventional example.
The rotor magnet 1 includes a rotating shaft 103 supported via a shaft, a rotor magnet 104 coupled to the rotating shaft 103, and a stator coil 106 fixed to a motor substrate 105 integrated with a housing 120 of the bearing 102.
Numeral 04 is disposed opposite to the stator coil 106, and both constitute a motor for driving the rotary polygon mirror 101 to rotate. The rotary polygon mirror 101 is pressed against the boss of the rotor magnet 104 by a pressing spring 107, and is integrated with this.

When the stator coil 106 is excited by a drive current supplied from a drive circuit 105a on the motor board 105, the rotor magnet 104 is rotated by the polygon mirror 1.
01, rotates at a high speed together with 01, and deflects and scans the light beam applied to the rotating polygon mirror 101 as described above.

The upper opening of the optical box 110 is
After the optical components such as the rotary polygon mirror 101 are incorporated therein, the lid 111 is closed.

[0007] As shown in FIG. 6B, the bearing 102 has a sleeve 12 held inside a housing 120.
1 and a rolling bearing having a pair of upper and lower ball rows 123 held on the inner side thereof via an outer ring 122. The sleeve 121 and the outer ring 122, and the sleeve 121 and the housing 120 are fixed to each other by a method such as adhesion. Have been.

[0008] Each ball row 123 is disposed between an inner ring 124 and an outer ring 122 formed by a groove of the rotating shaft 103, and the balls 123a of each ball row 123 are rotated by a retainer 125 as shown in FIG. It is held at equal intervals in the direction. The aforementioned motor is driven to rotate the rotating shaft 103.
Rotates, each ball 123a revolves around the rotating shaft 103 while rotating between the outer ring 122 and the inner ring 124, and supports the rotating shaft 103 for rotation. Grease 126 as a lubricant is dropped between the outer ring 122 and the retainer 125.

The fitting of each ball 123a of the ball row 123 with the outer ring 122 and the inner ring 124 is highly accurate, and the contact pressure of each ball 123a is extremely high. If such foreign matter is caught, troubles such as generation of loud noise, deterioration of accuracy due to damage of parts, and shortening of the life of the bearing occur. Therefore, a seal member 127 made of metal or plastic is attached to the outer ring 122 to close the bearing gap and to prevent dust and the like from entering the inside of the bearing.

[0010]

However, according to the above prior art, even if a seal member is attached to the outer ring in order to prevent dust or the like from entering the bearing gap, a slight gap is provided between the seal member and the rotating shaft. Since A ₀ is left, as shown in FIG. 8, in the step of integrating the rotor magnet 104 with the rotating shaft 103 by, for example, press-fitting, small wear caused by friction between the rotor magnet 104 and the rotating shaft 103. When powder X like falls along the rotation shaft 103, through the seal member 127 the gap a ₀ between the rotary shaft 103 easily penetrate into the bearing, the deterioration of the noise and bearing performance, that leads to short life, etc. There are unresolved issues.

A completely sealed structure has been developed in which the bearing gap between the rotating shaft and the outer ring is completely sealed with an elastic material such as rubber to prevent dust from entering the bearing. However, when a relatively lightweight component is rotationally supported with high precision, such as a rotary polygon mirror of an optical deflection scanning device, it is preferable because the load due to the contact of the elastic material hinders stable rotation. Absent.

In recent years, in particular, there has been a demand for an optical deflection scanning device having a quiet operation sound in addition to an increase in speed, and it is more important than ever to thoroughly prevent dust from entering a bearing portion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and effectively avoids entry of dust and the like into a rolling bearing that rotatably supports a rotary polygon mirror. It is another object of the present invention to provide an optical deflection scanning device capable of reducing noise generated from a bearing portion and greatly contributing to improvement in bearing performance and extension of life.

[0014]

In order to achieve the above object, an optical deflection scanning apparatus according to the present invention comprises: a rotary polygon mirror for deflecting and scanning a light beam; a rolling bearing for supporting the rotary polygon mirror;
A motor that rotationally drives the rotating polygon mirror; wherein the rolling bearing is a plurality of balls that are rollably held in a bearing gap between a rotating shaft and an outer ring; It is characterized by having a seal member configured to close the gap.

It is preferable that the seal member protrudes in the axial direction from the end surface of the outer race.

Preferably, a step is provided on the end surface of the outer race, and the seal member is arranged so as to overlap the step.

[0017]

The plurality of balls held in the bearing gap around the rotary shaft revolve while rotating on the rotation of the rotary shaft, thereby supporting the rotary shaft in rotation. When foreign matter such as dust enters the bearing gap, noise is generated or the bearing performance is deteriorated. Therefore, a seal member for closing the bearing gap is provided integrally with the rotating shaft. If the sealing member is integral with the rotating shaft, there is no gap between the sealing member and the rotating shaft. Therefore, abrasion powder or the like generated when the rotor magnet or the like is assembled to the rotating shaft by a method such as press-fitting is reduced. Even if you fall along
There is no danger that the above-mentioned troubles will be caused by entering the bearing gap.

[0018]

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

FIG. 1 shows an optical deflection scanning device according to an embodiment, which comprises a rotating shaft 3 supported by a rolling bearing 2 on an optical box 10 and a rotor coupled to the rotating shaft 3. Magnet 4 and housing 2 of rolling bearing 2
A stator magnet 6 is fixed to a motor substrate 5 which is integral with the motor 0. The rotor magnet 4 is disposed so as to face the stator coil 6, and constitutes a motor for rotatingly driving the rotary polygon mirror 1. The rotary polygon mirror 1 is pressed against the rotor magnet 4 by a holding spring 7 and is integrated with the rotor magnet 4.

When the stator coil 6 is excited by the drive current supplied from the drive circuit 5a on the motor board 5, the rotor magnet 4 rotates at a high speed together with the rotary polygon mirror 1, and as described above, the rotary polygon mirror The light beam irradiating 1 is deflected and scanned.

The upper opening of the optical box 10 is closed by the lid member 11 after incorporating optical components such as the rotary polygon mirror 1 into the optical box 10.

The rolling bearing 2 includes a sleeve 21 held inside a housing 20 and a pair of upper and lower ball rows 23 held further through an outer ring 22 inside the sleeve 21.
, The sleeve 21 and the outer ring 22, and the sleeve 21
The housing 20 and the housing 20 are fixed to each other by a method such as bonding.

Each ball row 23 is disposed in a bearing gap between the inner ring 24 and the outer ring 22 formed by the groove of the rotating shaft 3, and a plurality of balls 23 a of each ball row 23 are circumferentially moved by a retainer 25. It is held at equal intervals. When the motor is driven to rotate the rotating shaft 3 as described above, each ball 23a revolves around the rotating shaft 3 while rotating between the outer ring 22 and the inner ring 24, and supports the rotating shaft 3 for rotation.
Note that grease 26 as a lubricant is dropped between the outer ring 22 and the retainer 25.

Each ball 23a of the ball row 23 and the outer ring 22
And the inner ring 24 is fitted with high precision, and each ball 23a
Is extremely high. Therefore, if a foreign substance such as dust is caught between each ball 23a and the outer ring 22 or the inner ring 24, a loud noise is generated, the accuracy is deteriorated due to damage of parts, etc. Troubles such as shortening of bearing life are caused. In view of this, a method has been devised in which a seal member 27 is attached to the inner surface of the outer ring 22 to prevent dust and the like from entering the inside of the bearing.

The seal members 27 are provided one at each of the upper end and the lower end of the rolling bearing 2 to close a bearing gap between each outer ring 22 and the rotating shaft 3. 3 is integrated by a known method such as press fitting, and protrudes from the surface of the rotating shaft 3 toward the outer ring 22. Accordingly, the gap A ₁ is formed between the outer end and the outer ring 22 of the seal member 27.

Since the sealing member 27 is thus fixed to the surface of the rotating shaft 3, as shown in FIG. 2, wear powder X and the like generated when the rotor magnet 4 is pressed into the rotating shaft 3 are removed. Even if it falls along 3, it can be received by the seal member 27. Therefore, it is possible to prevent the wear powder X or the like from directly entering the inside of the rolling bearing 2 and, when the rotating shaft 3 rotates, the sealing member 2
Since the abrasion powder X and the like that have fallen on the surface 7 are blown off by the centrifugal force, the probability of dust entering the inside of the rolling bearing 2 is greatly reduced.

According to the present embodiment, by simply changing the mounting of the sealing member to the rotating shaft instead of the outer ring of the bearing, troubles such as noise due to dust entering the inside of the bearing, deterioration of the performance of the bearing, and shortening of life are extremely reduced. Can be avoided effectively.
As a result, it is possible to realize a high-performance and long-life optical deflection scanning device with quiet operation noise.

The shape of the motor for rotating the rotary polygon mirror is not limited to the radial gap type outer rotor type as shown in FIG. 1, but may be an axial gap type inner rotor type. Also, as the rolling bearing, any type of ball bearing of an inner ring rotating type can be applied.

FIG. 3 shows a first modification. This is shown in FIG.
The seal member 37 similar to the seal member 27 of FIG.
Are provided so as to protrude in the axial direction from the end face. The end face of the outer ring 32 is slightly (Δ
H) Since it is low, an advantage is added that when the abrasion powder X or the like is scattered by centrifugal force, it is surely discharged out of the bearing.

FIG. 4 shows a second modification. In this embodiment, a step portion 42 a is provided on the end surface of the outer ring 42, and the outer peripheral portion of the seal member 47 overlaps the step portion 42 a. Further, similarly to the first modification, the outer ring 4 is
2 is configured to be slightly (ΔH) lower. The abrasion powder X falls on the sealing member 47 and the outer ring 4
Even if it intrudes into the bearing, there is no possibility of intrusion into the bearing because it is received by the step portion 42a. An advantage is added that dust and the like can be more reliably prevented from entering the inside of the bearing.

FIG. 5 shows the entire light deflection scanning device.
It has a light source 51 that generates a light beam (light flux) such as laser light, and a cylindrical lens 51a that condenses the laser light linearly on the reflection surface 1a of the rotary polygon mirror 1.
The light beam is deflected and scanned by the rotation of the rotary polygon mirror 1 and passes through an imaging lens system 52 to a photosensitive drum 53 on a rotating drum.
Image. The imaging lens system 52 includes a spherical lens 52a,
It has a toric lens 52b and the like, and has a so-called fθ function for correcting the 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,
The angle between the optical path of the light beam condensed by the cylindrical lens 51a and the normal to the reflecting surface 1a of the rotating polygon mirror 1, that is, the angle of incidence of the light beam on the reflecting surface 1a, changes with time as the rotating polygon mirror 1 rotates. And the reflection angle also changes, so that the point image formed by condensing the light beam on the photoconductor 53 moves (scans) in the axial direction (main scanning direction) of the rotating drum.

The imaging lens system 52 focuses the light beam reflected by the rotary polygon mirror 1 on the photosensitive member 53 into a point image having a predetermined spot shape, and scans the point image in the main scanning direction. Is designed to keep the speed constant.

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 corona discharge device for uniformly charging the surface of the photosensitive member 53 is provided around the photosensitive member 53, and an electrostatic latent image formed on the surface of the photosensitive member 53 is visualized as a toner image. And a transfer corona discharger (both not shown) for transferring the toner image to recording paper, etc., and recording information by a light beam generated from the light source 51 is printed on recording paper or the like.

The detection mirror 54 reflects the light beam on the upstream side in the main scanning direction from the optical path of the light beam incident on the recording information write start position on the surface of the photoreceptor 53, and receives a light receiving element 55 having a photodiode or the like. To the light receiving surface of The light receiving element 55 outputs a scanning start signal for detecting a scanning 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 scanning start signal given from the light receiving element 55.

The rotary polygon mirror 1, the imaging lens system 52 and the like are housed in the optical box 10, and the light source 51 and the like are mounted on the side wall of the optical box 10. After the rotating polygon mirror 1, the imaging lens system 52, and the like are assembled in the optical box 10, the lid member 11 is attached to the upper opening of the optical box 10.

[0039]

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

It is possible to effectively prevent dust and the like from entering the inside of the rolling bearing that rotatably supports the rotating polygon mirror, reduce noise in the bearing portion, and greatly contribute to improving the bearing performance and extending the service life. . By mounting such a light deflection scanning device, it is possible to promote higher performance and longer life of the image forming apparatus.

[Brief description of the drawings]

FIG. 1 shows a main part of an optical deflection scanning apparatus according to an embodiment, (a) is a schematic sectional view thereof, and (b) is (a).
It is an expanded partial sectional view which expands and shows only a rolling bearing.

FIG. 2 is a diagram illustrating a state in which wear powder and the like fall on the rolling bearing of FIG. 1;

FIG. 3 is a partial sectional view showing a first modification.

FIG. 4 is a partial sectional view showing a second modification.

FIG. 5 is a diagram illustrating the entire light deflection scanning device.

6 (a) is a schematic cross-sectional view showing a conventional example, and FIG. 6 (b) is an enlarged partial cross-sectional view showing only the rolling bearing of FIG.

7 is a partially enlarged perspective view showing a part of the device of FIG. 6 in a further enlarged manner.

FIG. 8 is a diagram illustrating a state in which wear powder enters a bearing in the device of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating polygon mirror 2 Rolling bearing 3 Rotating shaft 4 Rotor magnet 6 Stator coil 21 Sleeve 22, 32, 42 Outer ring 23 Ball row 23a Ball 24 Inner ring 25 Retainer 27, 37, 47 Seal member

Claims (3)

[Claims] A rotary polygon mirror for deflecting and scanning a light beam;
A rolling bearing that rotatably supports this, a motor that rotationally drives the rotating polygon mirror, the rolling bearing is a plurality of balls rotatably held in a bearing gap between a rotating shaft and an outer ring, An optical deflection scanning device comprising a seal member integrated with a rotating shaft and configured to close the bearing gap. 2. The optical deflection scanning device according to claim 1, wherein the seal member protrudes axially from an end surface of the outer race. 3. A step portion is provided on an end surface of the outer ring,
The optical deflection scanning device according to claim 1, wherein a seal member is provided so as to overlap the step portion.