JP2957785B2 - Optical scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical scanning device, for example,
The present invention relates to an optical scanning device using a polygon scanner.

[0002]

2. Description of the Related Art A conventional optical scanning apparatus is disclosed in
FIGS. 3 and 4 described in JP-A-49725. The optical scanning device 1 shown in FIG. 3 is an exploded view of the optical scanning device 1. The optical scanning device 1 includes a flange 7 of an aluminum alloy motor casing 9 supporting the rotary polygon mirror 2, and an aluminum alloy or engineering plastic. Screw 15 directly with the optical housing 1A
It was attached with

On the optical housing 1A, an LD unit 3 and a first cylindrical lens 4 are arranged on an optical path for guiding the incident beam to the rotary polygon mirror 2, and fθ is provided on an optical path of the reflected light from the rotary polygon mirror 2. A lens 5 is arranged. Note that the LD unit 3 includes an LD and a collimator lens. The optical housing 1A is provided with a cylindrical portion 6 for forming a through hole at a position corresponding to the LD unit 3, the first cylindrical lens 4, and the fθ lens 5, and the cylindrical portion 6 is used for rotation of the rotary polygon mirror 2. It has a size that does not hinder.

[0004] The rotary polygon mirror 2 is driven by a motor 8 integrally formed with the rotary polygon mirror 2. The motor 8 is provided on the upper part of the casing 9 with the cylindrical portion 6 of the optical housing 1A.
The outer cylindrical portion 9a of the motor casing 9 is fitted and closely contacted with the lower inner peripheral surface 6a of the cylindrical portion 6 of the optical housing 1A. Flange 7 is optical housing 1A by screws 15,15
Is directly fixed to the bottom mounting hole.

A cylindrical portion 6 between the rotary polygon mirror 2 and the LD unit 3, the first cylindrical lens 4, and the fθ lens 5
A glass plate 10 is attached to the notch 6b by a means such as bonding to block the sound generated by the rotation of the rotary polygon mirror 2. On the upper surface of the cylindrical portion 6 having the through hole, a sound insulating plate 11 is attached with a screw 12.

Reference numeral 13 denotes a unit cover that covers the entire optical housing 1A, and is attached to the upper mounting hole on the optical housing 1 by screws 14. Briefly describing the optical scanning device 1, a laser beam turned on / off by an image output signal is converted into a parallel beam by an LD unit 3 and compressed in a sub-scanning direction by a first cylindrical lens 4.
Light passing through the sound insulating glass plate 10 and incident on one surface of the rotating polygon mirror 2 that is controlled to rotate at a constant speed, light beams scanned by the rotation of the rotating polygon mirror 2 pass through the sound insulating glass plate 10 again, and the fθ lens 5.
Forms an image on the surface of the photoreceptor 18 via the optical path changing mirror 16,
Further, the photosensitive member 18 is scanned at a constant speed. Therefore, a latent image as an aggregate of dots is formed on the photoreceptor 18 by the light beam sequentially scanned by each surface of the rotary polygon mirror 2.

At this time, the rotary polygon mirror 2 rotates at a rotation speed determined by the linear speed of the photosensitive member 18, the image density, the number of mirror surfaces, etc., and the rotation speed is several thousand to 40,000 rotations / minute. Therefore, the rotation of the polygonal rotating polygon mirror 2 generates noise such as wind noise and noise accompanied by high frequency of the bearing portion.
Vibration also occurs due to imbalance of the rotating body described later.

With the above configuration, the rotary polygon mirror is surrounded by a part of the optical housing 1A that supports the respective optical systems of the LD unit 3, the first cylindrical lens 4, and the fθ lens 5 located in front of the rotary polygon mirror 2. And a lower through hole of the cylindrical portion 6 is formed by the rotating polygon mirror 2.
Outer peripheral cylindrical portion 9a of the casing 9 of the motor 8 supporting the
Thus, the upper through-hole of the cylindrical portion 6 is formed by the sound insulating plate 11, and the cutout 6 b between the rotary polygon mirror 2 and the optical system is formed by the glass plate
Thereby, the surroundings of the rotary polygon mirror 2 are completely surrounded, whereby the sound generated from the rotary polygon mirror 2 can be completely cut off.

Next, a so-called high-speed polygon scanner 20 including a motor 8 that supports the rotary polygon mirror 2 and rotates the rotary polygon mirror 2 at high speed will be described with reference to FIG. The bearing of the polygon scanner 20 includes a fixed shaft 22 having a herringbone groove 22a shrink-fitted on a fixed shaft pedestal 21 as an air dynamic pressure radial bearing portion, a cylindrical hollow rotating shaft 23 outside the fixed shaft 22, and a thrust. The magnetic bearing 24 is composed of three magnets 24a, 24b, 24c. Hollow rotating shaft 23
The polygon mirror 2, which is a rotating polygon mirror, is mounted on the mirror receiver 23a on the upper side by mounting screws 28 via a mirror retainer 26. The motor unit of the rotary drive source includes a rotor magnet 29 fixed to the hollow rotary shaft 23 and a stator 30 fixed to the casing 9. The polygon mirror 2 is rotated at a constant speed by a driver (not shown).
The hollow rotary shaft 23, the rotary polygon mirror 2, and the mirror retainer 26 form a rotary body 27. Other main components are a motor casing 9, a cylindrical portion 6 of the optical scanning device 1, which is an optical housing for covering the polygon mirror 2, an upper lid 32 also having a function of holding the magnetic bearing magnet 24 c, Window 3
3, balance ring 34 to balance the rotating body,
Adjuster for mirror holder 26 with balance ring function
26a, an orifice 35 provided at the center of rotation of the mirror retainer 26 which also has a function of holding the magnetic bearing magnet 24b to provide high damping characteristics in the axial direction, a Hall element 36 for detecting the position of the rotor magnet in the motor section, and a motor section. This is a wiring substrate 38.

[0010]

However, in such a conventional optical scanning device 1, a polygon scanner is used.
When the rotor 20 is rotating at high speed, if there is a slight imbalance in the rotating body 27, the occurrence of the imbalance and the vibration and noise resulting from the imbalance increase rapidly and cannot be ignored. Less than,
FIG. 4B shows the relationship between the unbalance and the vibration of the rotating body 27.
This will be described below.

Assuming that the mass of the rotating body 27 is M, if the position of the center of gravity of the rotating body 27 rotates with eccentricity by ε with respect to the rotation axis OO, an imbalance of Mε will occur .
The balance class G at this time is represented by the peripheral speed at the position of the center of gravity, and is expressed by the following equation: G [mm / s] = ε · ω. Here, ω is the angular velocity of rotation.

When the rotating body 27 rotates at high speed several thousands to tens of thousands of times per minute, the angular velocity ω becomes very large,
In order to keep the eccentricity small, it is necessary to keep the eccentricity ε small. In general, in order to measure the amount of eccentricity ε, an inverse calculation can be performed from the relationship of Mε = mγ by measuring the unbalanced mass m of γ on an arbitrary radius.

The centrifugal force f when rotating the unbalanced rotating body 27 at an angular velocity ω is expressed by the following equation: f = Mεω ² = mγω ² That is, an exciting force corresponding to the centrifugal force f is generated for each rotation of the rotating body 27, and vibration is generated. This centrifugal force f is proportional to the unbalance amount Mε, and the angular velocity ω is 2
It is proportional to the power. Therefore, the rotation of the rotating body 27 is 14,0 per minute.
When the rotation becomes 00 or more, the exciting force also rapidly increases. In order to suppress this vibration, it is necessary to produce a rotating body 27 having a very small unbalance amount Mε. In other words, it is necessary to perform a precise and time-consuming precision balance correction operation, which increases the assembly cost. Also, as can be seen from the above equation, the centrifugal force increases with the square of the rotation speed (angular velocity) , so that the rotation speed becomes 14,000 times / min or more.
Then, there is a problem that the balance correction becomes extremely difficult .

As described above, the vibration of the rotating body 27 is caused by the fact that the flange 7 of the motor 8 is directly connected to the optical housing 1A, that is, the lower part of the cylindrical portion 6 of the optical housing 1A by the screw 15. Since it is mounted, the vibration generated by the imbalance of the high-speed rotating body 27 including the rotary polygon mirror 2 is transmitted as it is to the optical housing 1A and the base plate 17 supporting the optical housing 1A,
There is a drawback in that it hinders precise optical positioning and that the output image dot positions are not aligned. Further, there is a secondary disadvantage that the level of noise generated by vibrating various structures fixed around the base and the base plate 17 is increased.

Further, in order to suppress the vibration and noise around the optical housing 1A and the base plate 17 below the specification values, it is necessary to build a precision rotating body 27 having a very small unbalanced amount. However, there is a problem in that the precision balance correction work which takes a long time must be performed, and the assembly cost increases. The present invention has been made against such a background art, and supports an optical housing and an optical housing by interposing an elastic member between the motor and the housing to generate vibration generated by the motor of the polygon scanner. Hard to reach around the base plate,
In addition to reducing the vibration of the optical scanning device, reducing the noise generated, and relaxing the balance of the rotating body of the motor including the polygon mirror of the polygon scanner, the time required for the balance correction work is reduced. To reduce the cost of work, and especially, the number of revolutions of the rotating body is 14,000 times /
By applying to a polygon mirror using a rotating polygon mirror of more than one minute, the balance correction work can be simplified and shortened,
It is possible to reduce the cost, furthermore, it is possible to block the inside from dust and moisture from the outside by using a rubber with good sealing performance, and furthermore, by using a rubber of appropriate hardness, without impairing the sealing performance It is another object of the present invention to provide an optical scanning device capable of easily performing optical positioning.

[0016]

According to a first aspect of the present invention, there is provided an optical scanning device for mounting a motor for rotating a rotary polygon mirror on a housing and scanning a light beam by the rotary polygon mirror. An elastic member is provided between them. According to a second aspect of the present invention, in addition to the configuration of the first aspect, the number of rotations of the rotary polygon mirror per minute is 14,000 or more.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the elastic member is made of rubber. According to a fourth aspect of the present invention, in addition to the configuration of the first, second or third aspect, the elastic member has a rubber hardness Hs of 50 or more. Claim
The invention described in claim 5 provides the configuration according to claim 1 or 2,
The elastic member is not balanced by the motor that drives the rotating polygon mirror.
It is characterized by being an elastic member that attenuates vibration.

[0018]

According to the first aspect of the present invention, since the elastic member is provided between the housing and the motor, vibration and noise of the motor are absorbed and cut off as internal loss of the elastic member . Particularly, the motor according to the fifth aspect of the present invention
The use of an elastic member that attenuates the unbalanced vibration of
It is. In the second aspect of the present invention, the rotation region in which the rotational speed of the rotating polygon mirror is 14,000 times / per minute or more, i.e., in order Do increase with the square of the excitation force rotational speed (angular velocity), General
By applying to the rotation speed region where vibration is large and balance correction work becomes difficult , balance correction work becomes easier.
Work time can be reduced.

According to the third aspect of the present invention, since the elastic member is made of rubber and has sealing properties, dust and moisture from the outside hardly enter. According to the fourth aspect of the present invention, since the rubber has a hardness of Hs50 or more, the motor is fixed to the housing with an appropriate hardness, and optical positioning becomes easy.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a first embodiment of an optical scanning device according to claims 1 to 4 of the present invention. The same components as those of the conventional optical scanning device shown in FIG. . First, the configuration will be described. In FIG. 1, reference numeral 41 denotes a large-sized optical scanning device. The optical scanning device 41 has a motor 8 for driving the rotary polygon mirror 2 to rotate. The optical housing 1A containing the rotary polygon mirror 2 and the optical path changing mirror 16 are provided. Frame supporting
This is a case in which the present invention is applied to a large optical system in which 19 and 19 are configured separately. This has the advantage that the optical housing 1A can be small. 19A is dustproof glass. Also, the optical scanning device 41 has a rotating polygon mirror 2 with a rotation speed of 14,000 times or more per minute,
For example, it scans a light beam having a high rotation speed of 16,000 times per minute and entering the rotary polygon mirror 2. In the optical scanning device 41, a sheet-like fluoro rubber rubber ring 43 as an elastic member is provided between the flange 7 of the casing 9 supporting the motor 8 and the optical housing 1A. It is attached to the optical housing 1A via the optical housing 1A. The hardness Hs of the rubber of the rubber ring 43 is 50 degrees or more of JISA, for example, 55 degrees.

Next, the operation will be described. According to the present invention, the optical scanning device 41 has a rotational speed of the rotary polygon mirror 2 of 16,0 / min.
Since it has 00 high-speed rotations, the centrifugal force f applied to the rotating body 27 that supports the rotating polygon mirror 2 becomes an extremely large value compared to the square of the angular velocity ω as shown in the equation, and the excitation force However, the balance correction work requires a long time, but the optical scanning device 41 of the present invention includes the flange 7 of the casing 9 and the optical housing 1.
A rubber ring 43 which is an elastic member is provided between the rubber ring 43 and the rubber ring 43, so that vibration and noise of the motor 8 are absorbed by the rubber ring 43 and cut off by the rubber ring 43. By the action, transmission of vibration and noise to the optical housing 1A side is greatly reduced.

The number of rotations of the rotary polygon mirror 2 is 16,000 times /
Even at a high speed per minute, the vibration to the optical housing 1A and the base plate 17 is difficult to be transmitted, and the vibration can be reduced, and therefore, the level of noise caused by the vibration can be reduced. Therefore, the standard of the grade of the good balance of the high-speed rotating body 27 can be relaxed, the correction work can be simplified for the balance correction, the time can be shortened, and the operation cost can be greatly reduced.

Further, since the rubber ring 43 is made of fluoro rubber, it has excellent weather resistance and deterioration resistance, and also has excellent sealing properties, so that dust, humidity, etc., which the optical parts dislike, can be blocked. Further, wind noise generated by the rotary polygon mirror 2 can be shielded to the outside. Furthermore, since the rubber ring 43 has a hardness of about Hs55 °, it has an appropriate hardness, can easily perform optical positioning without deteriorating the sealing performance, and can perform assembly work in a short time. Can be.

Next, a second embodiment of the present invention will be described. FIG. 2 is a diagram showing a second embodiment of the optical scanning device according to the first to fourth aspects of the present invention. The same reference numerals are given to the same components as those in the first embodiment. The optical scanning device 51 shown in FIG. 2 is a case where an O-ring 53 having a circular cross section is used instead of the rubber ring 43 of the first embodiment. It is suitable for the system. In this case, in addition to the same functions and effects as those of the first embodiment, an O-shape having a circular cross section is used.
With the ring 53, the same vibration and noise shielding effect can be obtained at a lower cost.

[0025]

According to the first aspect of the present invention, the vibration caused by the unbalance of the rotating body of the motor including the rotary polygon mirror is reduced.
By interposing an elastic material between the polygon motor and the optical housing, it is difficult to transmit to the optical housing, and the vibration around the optical housing and the base supporting the optical housing can be reduced. The level of generated noise can also be reduced.

According to the second aspect of the present invention, since the grade of good balance of the high-speed rotating body can be relaxed, the higher the speed, the more difficult and time-consuming the work of correcting the balance, and the time is shortened. And work costs can be reduced. According to the third aspect of the present invention, since the sealing property is improved by the rubber, the optical components such as the lens and the rotary polygon mirror can be shielded from external dust and moisture. Furthermore, wind noise generated by the rotating polygon mirror can be shielded to the outside.

According to the fourth aspect of the present invention, since the elastic member has elasticity of an appropriate hardness, optical positioning can be easily performed without impairing the sealing performance. Claim 5
According to the described invention, a bullet that attenuates unbalanced vibration of a motor
The effect of claim 1 can be enhanced by using the conductive member.
Wear.

[Brief description of the drawings]

FIG. 1 shows a first example of an optical scanning device according to claims 1 to 4 of the present invention.
FIG. 3 is a view showing an embodiment, (a) is an exploded perspective view thereof, and (b) is
It is principal part sectional drawing including the optical path changing mirror .

FIG. 2 shows a second embodiment of the optical scanning device according to claims 1 to 4 of the present invention.
FIG. 4A is a view showing an embodiment, in which FIG.
It is principal part sectional drawing including the optical path changing mirror .

3A and 3B are views showing a conventional optical scanning device, in which FIG. 3A is an exploded perspective view, and FIG. 3B is a sectional view of a main part including an optical path changing mirror .

4A and 4B are diagrams showing a polygon scanner of the optical scanning device shown in FIG. 3, wherein FIG. 4A is an overall sectional view and FIG. 4B is an explanatory diagram showing an unbalanced state.

[Explanation of symbols]

 1A Optical housing (housing) 2 Rotating polygon mirror 8 Motor 41, 51 Optical scanning device 43 Rubber ring (elastic member) 53 O-ring (elastic member)

Claims (5)

(57) [Claims] 1. An optical scanning device for rotating a rotating polygon mirror for driving a rotating polygon mirror in a housing and scanning a light beam by the rotating polygon mirror, wherein an elastic member is provided between the housing and the motor. Optical scanning device. 2. The rotating polygon mirror has a rotation number of 1 per minute.
2. The optical scanning device according to claim 1, wherein the number is 4,000 or more. 3. An optical scanning device according to claim 1, wherein said elastic member is rubber. 4. The optical scanning device according to claim 1, wherein said elastic member has a rubber hardness Hs of 50 or more. 5. A motor for driving a rotary polygon mirror.
Characterized by an elastic member that dampens unbalanced vibration
The optical scanning device according to claim 1 or 2, wherein