JP2000147416A - Optical deflecting scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a rolling bearing rotatably supporting a rotary polygon mirror from getting in the faulty lubricant state. SOLUTION: The rolling bearing 2 rotatably supporting the rotary polygon mirror 1 holds a ball train 23 between an outer ring 22 and an inner ring 24. The slick of oil supplied from grease 26 is formed on the surface of the rolling groove 22a of the outer ring 22 or the rolling groove 24a of the inner ring 24. In order to prevent a situation that the slick is gradually thinned by centrifugal force and the faulty lubricant state is caused, a notch 29 is formed in the rolling groove 24a of the inner ring 24 and the oil is partially accumulated in the notch 29.

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. 4 shows a main part of an optical deflection scanning apparatus according to a conventional example.
, A rotating magnet 103 integrally supported by the rotating shaft 103, and a bearing 1
02 and the motor board 105 integrated with the housing 120
, And the rotor magnet 104 is disposed so as to face the stator coil 106, and both constitute a motor that drives 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. 4 (b), 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.
Is rotated, each ball 123a revolves around the rotating shaft 103 while rotating between the outer ring 122 and the inner ring 124, and rotatably supports the rotating shaft 103. The outer ring 1
Grease 1 which is a lubricant between the nozzle 22 and the retainer 125
26 have been dropped.

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.

As described above, the inner ring 124 is
However, similarly to the outer ring 122, the annular member serving as the inner ring 124 may be manufactured as a separate body and fixed to the rotating shaft 103.

The ball 123a of each ball row 123 has a pressurizing spring 12 for urging the upper and lower outer rings 122 in opposite directions.
8 presses against the inner race 124. That is, the pressurizing spring 128 is incorporated between the upper and lower outer rings 122 in a compressed state.
As shown by the arrow A, the ball row 123 is restrained between the rolling groove 124a of the inner ring 124 and the rolling groove 122a of the outer ring 122, and as a result, the ball 123a revolves on a fixed track. The retainer 125 is provided so that the ball 123a revolves while keeping a constant interval in the circumferential direction. The seal member 127 is made of metal or plastic material, and is fixed to the outer ring 122 by a known method such as press fitting.

When the rotating shaft 103 rotates, each ball 123a revolves around the rotating shaft 103 while rotating between the inner ring 124 and the outer ring 122, and rotatably supports the rotating shaft 103. As described above, the ball 123a and the inner race 12
4. At the contact portion of the outer ring 122, a compression force (pressurization) acts on the ball 123a as shown by an arrow A in FIG. That is, the pressurized spring 128
Due to the preload, the ball 123a freely rotates in the circumferential direction around the axis, but is restrained in other directions. Therefore, the rotation of the rotating shaft 103 is free, and furthermore, shaft runout and axial vibration can be suppressed to an extremely small level. As a result, a high-precision bearing function required as an optical deflection scanning device can be realized.

The ball 123a, the inner ring 124 and the outer ring 122
The contact area is very small and is in contact with high pressure. For this reason, if the contact portion is dry or bites into dust or the like, a very loud noise is generated, and the component is damaged, thereby deteriorating accuracy and life. Therefore, generally, as shown in FIG. 5, grease 126 is sealed for lubrication.
The oil contained therein constantly wets the surface of each part of the bearing. It is very important that this oil film, or oil film, be maintained throughout the operation of the bearing. FIG. 6 shows the state of the oil film.

FIG. 6A shows a state where the bearing is not rotating. In the figure, the ball 123a, the inner ring 12
4. Only a part of the contact portion of the outer ring 122 is shown. During the stop, the distribution and thickness of the oil film are uniform, and are uniformly formed on the belt-like portion including the rolling trajectory R as represented by the shadow. Although the oil film also exists on the surface of the ball 123a and the outer ring 122, only the oil film on the surface of the inner ring 124 is shown here.

[0015]

However, the above conventional example has the following problems. FIG. 6B shows how the state changes from the state shown in FIG. 6A when the bearing continues to rotate. Rotating shaft 103
When but rotates, a centrifugal force in the oil acts, small rolling groove 124a of the oil as the rotation radius r ₁ is Yuki moves as indicated by an arrow turning radius to the shaft portion as large r _2, The oil film of the rolling groove 124a tends to be thin. Therefore, as the rotation of the rotating shaft 103 continues, the oil film near the rolling track R gradually becomes thinner, and finally becomes a state of poor lubrication, resulting in abnormal vibration noise and rapid wear of the bearing portion, and the bearing life. Cannot be achieved.

This phenomenon becomes more pronounced as the rotational speed of the bearing increases. In recent years, there has been an increasing demand for higher speed motors and lower operating noise of the apparatus, that is, quietness, and it has been desired to maintain and manage the lubrication state better than ever before.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and maintains a good lubricating state even when the rotation speed of a rolling bearing is high, and is quiet and accurate. It is an object of the present invention to provide a long-life, highly reliable light deflection scanning device.

[0018]

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 rotatably supporting the rotary polygon mirror; A motor for rotating the polygon mirror is provided, and at least one of the rolling grooves of the inner ring and the outer ring of the rolling bearing is provided with a notch in a circumferential direction for accumulating oil.

It is preferable that the notch of the rolling groove is provided in a region where the ball does not come into contact with the rolling groove.

[0020]

A circumferential cut is provided in the rolling groove of the inner ring or outer ring of the rolling bearing, or both the inner ring and the outer ring, so that a part of the oil for forming the oil film of the rolling groove is accumulated in the notch. To be configured.

When the rotation of the rotary polygon mirror continues, the oil film in the rolling groove tends to become thinner due to centrifugal force. However, the oil film accumulated in the cut in the rolling groove is gradually replenished, so that the oil film is interrupted. There is no risk of poor lubrication.

[0022]

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

FIG. 1 shows an optical deflection scanning apparatus according to an embodiment, which comprises a rotating shaft 3 supported on a optics box 10 via a rolling bearing 2 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 substrate 5, the rotor magnet 4 rotates at a high speed together with the rotary polygon mirror 1 and irradiates the rotary polygon mirror 1. The light beam is deflected and scanned.

The upper opening of the optical box 10 is closed by a 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 inside the housing 20 via outer rings 22.
, 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 between an inner ring 24 and an outer ring 22 formed by a groove of the rotating shaft 3. A plurality of balls 23 a of each ball row 23 are circumferentially spaced at equal intervals by a retainer 25. Is held. 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 rotatably supports the rotating shaft 3. 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 and lower ends of the rolling bearing 2, and seal the bearing gap between each outer ring 22 and the rotating shaft 3.

As described above, the inner race 24 is constituted by the rolling groove 24a formed directly on the outer peripheral surface of the rotating shaft 3. However, similarly to the outer race 22, the inner ring 24 is manufactured as a separate ring member. May be fixed to the rotating shaft 3.

The balls 23a of each ball row 23 are pressed against the inner ring 24 by a pressurizing spring 28 which urges the upper and lower outer rings 22 in opposite directions. That is, the pressurizing spring 28 is incorporated between the upper and lower outer rings 22 in a compressed state, and the ball row 23 is formed by the pressurizing of the pressurizing spring 28 so that the rolling groove 24a of the inner ring 24 and the rolling groove 22a of the outer ring 22 are formed.
As a result, the ball 23a revolves on a fixed trajectory (rolling trajectory R). As described above, the retainer 25 functions to keep the balls 23a at a constant interval in the circumferential direction. The seal member 27 is made of a metal or plastic material, and is fixed to the outer ring 22 by a known method such as press fitting.

In the rolling groove 24a of the inner race 24, an oil holding portion comprising a circumferential cut 29 is formed in the vicinity of the rolling track R. This is to stably maintain the oil film of the oil contained in the grease 26 so as not to be interrupted by the centrifugal force even during the rotation of the rotating shaft 3.

More specifically, FIG. 2A shows a state where the bearing is not rotating. For convenience, only a part of the contact state between the ball 23a and the inner ring 24 and the outer ring 22 is shown. FIG.
In (a), the oil film covering the surface of the rolling groove 24a of the inner race 24 is formed in the contact portion between the ball 23a and the inner race 24, that is, in the vicinity of the rolling track R, and is represented by a shadow. A similar oil slick is the ball 23
a and also on the surface of the rolling groove 22a of the outer ring 22.

During the stop, the distribution and thickness of the oil film are uniform.
The oil film at the contact portion between the ball 23a and the inner ring 24 exists sufficiently and uniformly.

FIG. 2B shows how the state changes from the state shown in FIG. 2A when the rotation is continued. When the rotating shaft 3 rotates, a centrifugal force acts on the oil, and the oil in the rolling groove 24a having a small rotating radius moves as shown by an arrow to a shaft portion having a large rotating radius. For this reason, the oil film of the rolling groove 24a gradually becomes thin, and a state of poor lubrication occurs. In order to prevent this, a cut 29 for accumulating a part of the oil is provided. The oil is caught in the cut 29 by capillary action, and the supply of the oil to the rolling track R gradually continues from here.

As a result, the oil film does not become thin and does not completely disappear. Accordingly, the lubrication state of the ball 23a and the inner ring 24 is almost the same as that during stop, and the rolling bearing 2 can maintain a quiet and long-life rotation.

Note that the motor and the rolling bearing are not limited to the shapes described above. For example, in this embodiment, the motor is a radial gap type outer rotor type, but may be an axial gap type or an inner rotor type. The rolling bearing is not limited to the inner ring (shaft) rotating type rolling bearing, but may be an outer ring rotating type rolling bearing. The cut may be provided on the outer ring side in the case of an outer ring rotating type rolling bearing. Also, notches are provided on both the inner and outer rings,
The overall oil holding capacity may be improved.

With such a structure, the lubricating state of the rolling bearing can be maintained in a good condition, and a long life, quiet and high precision bearing can be realized even at a high speed rotation. Can greatly contribute to

FIG. 3 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 formed 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.

Around the photosensitive member 53, a charging device for uniformly charging the surface of the photosensitive member 53, and a charging device for visualizing an electrostatic latent image formed on the surface of the photosensitive member 53 into a toner image. A developing device, a transfer device for transferring the toner image to recording paper, and the like are arranged, 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 write start position of the recording information 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 the 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 to the light receiving element 55
Are transmitted in synchronization with the scanning start signal given by

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.

[0047]

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

The rolling bearing that rotatably supports the rotating polygon mirror is effectively prevented from being in a state of poor lubrication, the quietness of the bearing portion is maintained, and the bearing performance is greatly improved and the life is extended. Can contribute. 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 an oil film formed on a bearing portion indicated by an ellipse B in FIG.

FIG. 3 is a diagram illustrating the entire light deflection scanning device.

4 (a) is a schematic cross-sectional view showing a conventional example, and FIG. 4 (b) is an enlarged partial cross-sectional view showing only a rolling bearing of FIG.

5 is a partially enlarged perspective view showing a part of the apparatus of FIG. 4 in a further enlarged manner.

6 is a diagram illustrating an oil film formed on a bearing portion indicated by an ellipse B in FIG.

[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 Outer ring 22a, 24a Rolling groove 23 Ball row 23a Ball 24 Inner ring 25 Retainer 27 Sealing member 28 Pressing spring 29 Notch

Claims (2)

[Claims] A rotary polygon mirror for deflecting and scanning a light beam;
A rolling bearing that rotatably supports the rotating polygon mirror; and a motor that rotationally drives the rotating polygon mirror. A circumferential direction for accumulating oil in at least one rolling groove of an inner ring and an outer ring of the rolling bearing. An optical deflection scanning device characterized in that a notch is provided. 2. The optical deflection scanning device according to claim 1, wherein the notch of the rolling groove is provided in a region where the rolling groove does not contact the ball.