JPH06130314A - Optical deflector - Google Patents

Abstract

PURPOSE:To provide the optical deflector which has high rotation precision and low vibration characteristics by preventing the rigidity of a dynamic pressure air bearing from decreasing. CONSTITUTION:A rotary polygon mirror 11 and a magnet yoke 5 which supports rotary magnets 6-1 and 6-2 are fixed and a rotary sleeve 3 which constitutes a fixed shaft 1 and the dynamic pressure air bearing are composed of a cylinder part 3-1 and a mirror flange 3-2 which is fixed to the outer periphery of the cylinder part 3-1 across a magnetic which has a smaller Young's modulus than the cylinder part 3-1. The centrifugal force based on the rotation of the rotary polygon mirror 1 operates only on an external cylinder part and the gap between the fixed shaft 1 and internal cylinder part does not expand, so the rigidity of the dynamic pressure air bearing does not decrease and a decrease in rotation precision and the generation of resulting vibration can be evaded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light for rotating a rotary polygonal mirror having a plurality of reflecting mirror surfaces on its outer periphery and reflecting a light beam incident on the reflecting mirror surfaces to deflect and scan the image carrier or a recording member. Regarding the deflector.

[0002]

2. Description of the Related Art Generally, an image reading device that scans an image carrier or the like with a light beam emitted from a light source such as a laser to read the image, or a recording medium with a light beam modulated by an image signal or a character signal. In the image recording apparatus for recording an image by using the rotary polygonal mirror having a plurality of reflecting mirror surfaces on its outer circumference, a means for scanning the light beam is used.

As an optical deflector of this type, a rotary bearing, which is preferably a dynamic pressure air bearing or the like, in which one of a sleeve and a shaft, which are inserted into each other, is a rotating member, and the other is a fixed member, is attached to the rotating member. A rotating torque generating function for generating a rotating torque by a magnetic circuit formed by winding an electromagnetic coil around a permanent magnet (magnet) and an annular iron core (stator core) installed on a fixed member, which constitutes a so-called scanner motor, and a rotating body in the axial direction. There is known an optical deflector having a magnetic circuit that also has the function of a magnetic bearing that holds the.

FIG. 5 is an explanatory view of a schematic structure of an image recording apparatus using this type of optical deflector, in which 30 is a laser and 31 is a laser.
Is a collimator lens, 32 is a condensing optical system, 33 is a photoconductor as a recording medium, 53 is a rotating polygon mirror, 53-1 is a plurality of reflecting mirror surfaces constituting a rotating polygon mirror, and 57 is a rotation driving mechanism (scanner motor). Reference numerals 58 and 58 denote dust-proof covers (hereinafter simply referred to as covers), and 58-1 denote openings (entrance / emission windows) through which light beams enter and exit.

In the figure, the rotary polygon mirror 53 is rotated in the direction of arrow A by a scanner motor 57. A light beam emitted from a laser 30 such as a semiconductor laser or a gas laser is modulated by an image signal or the like by a modulation means (not shown), and is incident on the reflecting mirror surface 53-1 of the rotary polygon mirror 53.
The light beam (reflected light beam) reflected by the reflecting mirror surface 53-1 of the rotating polygonal mirror 53 passes through the condensing optical system 32 and the photoconductor 3
3 is projected.

This reflected light beam is deflected in the direction of arrow B as the rotary polygon mirror 53 rotates in the direction of arrow A, and is reflected by the photosensitive member 3.
3. Main scanning is performed on the upper part. Along with this, sub-scanning is performed by rotation of the photoconductor 33 in the direction of arrow C, and a two-dimensional image is written on the photoconductor 33. A dustproof cover 58 having a light beam entrance / exit window 58-1 is attached to prevent dust from adhering to the reflecting mirror surface 53-1 of the rotary polygon mirror 53.

FIG. 6 is a sectional view for explaining the structure of an example of a conventional optical deflector, in which 1 is a fixed shaft, 1-1 is a groove for generating dynamic pressure, 2-1 is a housing, and 2-2 is A housing adapter, 3 is a rotary sleeve, 3-1 is a mirror flange, 5 is a magnet yoke, 6 is a magnet including an inner magnet 6-1 and an outer magnet 6-2, 7 is a stator core, and 8-1, 8- 2 is a stud, 9 is a circuit board, 10 is a magnetic detection element, 11 is a rotating polygon mirror, 11-1.
Is a reflecting mirror surface, 12 is a cap flange, 13, 16, 1
7, 18, 20 are screws, 15 is a gap, 21 is a collar, 2
2 is a damper, 23 is an air trap, and 24 is a fine hole. The cover shown in FIG. 5 is omitted.

This optical deflector has its axis 1 fixed, and this axis 1
The sleeve inserted into the shaft is of a fixed shaft type that rotates. Here, the shaft 1 will be described as a fixed shaft, and the sleeve 3 will be described as a rotating sleeve. In FIG. 6, one end of the fixed shaft 1 is fixed to the housing 2-1 and the housing 2-1 is fixed to the housing adapter 2-2 with screws 16 and 20.

On the peripheral surface of the fixed shaft 1, a dynamic pressure generating groove 1-1 which functions as a radial bearing is provided. This radial bearing is a bearing for preventing the center of rotation from deviating from a predetermined position even when a force acts in a direction perpendicular to the axial direction. The rotor portion constituting the scanner motor is a portion inserted into the fixed shaft 1 with a gap 15 therebetween, and is fixed to the rotary sleeve 3 and the magnet yoke 5 fixed to the rotary sleeve 3 by press fitting or adhesion. It is composed of magnets 6-1 and 6-2.

A rotary polygon mirror 11 is attached to this rotor portion. The rotary polygon mirror 11 is attached by the polygon mirror 11
The center hole is attached to the rotary sleeve 3, the cap flange 12 is applied from above, and the screw 13 is fixed to the mirror flange 3-1 of the rotary sleeve 3. Between the upper end of the fixed shaft 1 and the cap flange 12,
An air pocket 23 that suppresses damping in the thrust direction (axial direction) is formed. The fine holes 24 communicate the air pocket 23 with the outside air to stabilize the damping effect of the air pocket 23. It should be noted that the damper 22 and the housing 2 are connected to each other when the rotor portion is stopped.
This is to prevent direct contact with 1.

On the other hand, the stator portion constituting the scanner motor is a housing 2-1 and a shaft housing adapter 2-fixed to the housing 2-1 with screws 16 and 20.
2. A fixed shaft 1 and an electromagnetic coil, which is preferably a toroidal coil, are wound around the housing 2-1 and a screw 2 is provided via a collar 21.
A stator core 7 fixed by 0, a circuit board 9 supported by studs 8 attached to the stator core 7, a magnetic detection element (sensor) 10 suitable for a hall element installed on the circuit board 9, and the like. Has been done.

The magnets 6 (inner magnets 6-1 and outer magnets 6-2) constituting a so-called scanner motor portion for rotating the rotary polygon mirror 11 are permanent magnets, and are magnetized between the opposing stator cores 7. Attractive force is working. This attractive force acts so that the opposing positions of the magnet 6 and the stator core 7 are not displaced in the axial direction (thrust direction) of the motor.

That is, when the magnet 6 moves to the right, a component that pulls back to the left appears in the attraction force and is pulled back, and when it moves to the left, a component that pulls back to the right appears and pulls back. Thus, the magnet 6 and the stator core 7 are made to face each other at a predetermined axial position by the magnetic attraction force. That is, the magnet 6 and the stator core 7 form a magnetic thrust bearing.

As the magnetic detection element 10, for example, a Hall element is used. This detects the leakage magnetic flux of the magnet 6 and detects whether the N pole or the S pole has passed when the magnet 6 rotates. The detection signal of the magnetic detection element 10 is sent to a control circuit unit (not shown) through the wiring printed on the circuit board 9. The control circuit section determines the direction of the current flowing through the electromagnetic coil wound around each part of the stator core 7 based on this detection signal. As a result, the interaction with the magnet 6 generates a force in the direction of continuing the rotation. The magnetic poles of the outer magnet 6-2 facing the magnetic poles of the inner magnet 6-1 are arranged so as to have the same poles.

When the rotary sleeve 3 rotates, the dynamic pressure generating groove 1-1 produces an air layer of high pressure around the shaft 1 (the gap 15). This pressure forms a dynamic air bearing in which the rotary sleeve 3 is supported in a state of floating above the shaft 1. In the figure, the dynamic pressure generating groove 1-
Although 1 is provided on the outer periphery of the fixed shaft 1, a dynamic pressure generating groove 1-1 may be provided on the inner wall of the rotating sleeve 3 instead of this.

The air layer in the gap 15 acts to keep the center of rotation of the rotor part constant. For example, if the rotary sleeve 3 is displaced to the left in the figure, the gap of the gap 15 on the right becomes large, and the pressure in the gap in this portion becomes smaller than that before the displacement. On the other hand, since the gap on the left side is small, the pressure in the gap in this part is larger than that before the gap. When the magnitude relation of the pressure is as described above, the rotary sleeve 3 is pushed rightward and finally returned to the original position.

FIG. 7 is an explanatory view of the optical deflector and its operation, and is a top view of FIG. 5 seen from the cap flange 12 side. In the figure, the rotary polygon mirror 11 has a regular polygonal shape when viewed from above in the axial direction, and has a large number of reflecting mirror surfaces 11-1 on its outer circumference (side surface). The incident light beam of the laser or the like is reflected by the reflecting mirror surface 11-1 of the rotary polygon mirror 11 and emitted toward the medium to be scanned such as the photoconductor drum.

When the light beam is incident on the reflecting mirror surface and the rotary polygon mirror 11 rotates, the direction of the reflected light beam of the light beam is gradually changed and deflected. As the rotation progresses,
As the next mirror surface rotates, the light beam in turn strikes it. With this reflecting mirror surface, deflection is performed in the same manner as the previous reflecting mirror surface. Therefore, the reflected light beam scans a certain angular range, and its scanning speed depends on the rotation speed of the rotary polygon mirror 11.

The above-mentioned optical deflector is a fixed shaft type in which the shaft 1 is fixed, but a rotating shaft type in which a sleeve is fixed to a housing and a rotary shaft is inserted into this is also known. A conventional technique relating to this type of optical deflector is disclosed in, for example, JP-A-62-23.
It is disclosed in Japanese Patent No. 1922.

[0020]

However, the rotary polygon mirror rotates at a high speed to deflect light, and a large centrifugal force is applied to the rotor portion by the high speed rotation. In the above prior art, the rotary sleeve 3 is locally deformed due to the shape and mass of the rotary flange 3 in which the mirror flange 3-1 for fixing the rotary polygon mirror 11 is integrated, which lowers the rigidity of the dynamic pressure air bearing. As a result, there is a problem in that the rotation accuracy is deteriorated, and vibration is caused, which deteriorates not only the optical deflector but also the performance of the entire optical system.

In other words, the rotation of this type of optical deflector must be highly accurate, and it is a major issue to increase its speed. To realize high-speed rotation, the rigidity of the dynamic pressure air bearing is required. Needs to be optimized. The rotating sleeve requires a mirror flange to securely hold the rotating polygon mirror. The mirror flange is required to have a required shape, size, and thickness so that it can be adapted to high-speed rotation, and it is also required to be a high-rigidity member having a hole for a screw to fix the rotating polygon mirror. It

However, when this mirror flange is integrated with the rotary sleeve, the inner wall of the rotary sleeve is distorted due to the shape and mass of the mirror flange due to high-speed rotation, and the rotary sleeve corresponding to the mirror flange portion is distorted. The inner diameter will increase. When the inner diameter of the rotary sleeve increases, the air layer that generates the dynamic pressure becomes wider in the radial direction, and the rigidity of the dynamic pressure air bearing decreases.

FIG. 8 is a sectional view of an optical deflector similar to FIG. 6 for schematically explaining the problems in the prior art. The same reference numerals as those in FIG. 6 correspond to the same parts, and 27 is an inner diameter deformation. It is a department. As shown in the figure, as the rotation of the rotary polygon mirror 11 increases, the inner wall of the rotary sleeve 3 in the mirror flange 3-1 portion is deformed in the radial direction, and the inner diameter deformed portion 27.
To form. That is, the inner diameter of the rotary sleeve 3 is enlarged, the air pressure in the gap 15 is reduced, the rigidity of the dynamic pressure air bearing is lowered, the rotation accuracy is lowered, and the vibration is caused. There is a problem that performance and reliability of peripheral devices such as lenses are deteriorated.

In the prior art disclosed in Japanese Utility Model Laid-Open No. 1-172017, which is proposed in view of this problem, the position where the mirror flange of the rotary sleeve is formed is a portion of the shaft where there is no dynamic pressure air generating groove, for example, FIG. In the above, it corresponds to the boundary portion between the upper and lower two sets of dynamic pressure air bearing portions. However, if the mirror flange forming portion of the rotary flange is fixed at a specific position, there is a drawback that the degree of freedom in designing the optical deflector is narrowed.

An object of the present invention is to solve the above-mentioned problems of the prior art, prevent the deterioration of the rigidity of the dynamic pressure air bearing, and provide the light with high rotation accuracy and low vibration characteristics even in the high speed rotation state of the rotary polygon mirror. It is to provide a deflector.

[0026]

In order to achieve the above object, the present invention provides an optical deflector having a dynamic air bearing structure as a bearing of a scanner motor having a rotary polygon mirror.
Attach the rotating sleeve to the cylindrical inner cylinder and the outer peripheral surface of this inner cylinder via an elastic material such as an adhesive or a material having a lower rigidity than the rotating sleeve (a material with a smaller Young's modulus), and centrifuge at high speed. By absorbing the force with the elastic material or the intervening material, the deformation of the inner wall of the rotary sleeve inserted through the shaft is avoided, and the function of the dynamic pressure air bearing is maintained.

Further, according to the present invention, the rotary sleeve is composed of a cylindrical inner cylinder portion and an outer cylinder portion having a mirror flange portion so that the centrifugal force generated at high speed rotation does not reach the inner cylinder. Characterize. That is, the invention described in claim 1 is a rotation part having at least a housing portion 2-1, a stator core 7 around which an electromagnetic coil is wound, and a fixed shaft 1, and a plurality of reflecting mirror surfaces 11-1 formed on the outer periphery. The polygonal mirror 11 and the magnet yoke 5 supporting the rotary magnets 6-1 and 6-2 are fixed to a rotor portion having at least a rotating sleeve 3, and a fixed shaft 1 of the stator portion has a sleeve 3 of the rotor portion. In a light deflector in which the bearing is supported by a dynamic pressure air bearing, a cylindrical portion 3-1 in which the rotary sleeve 3 constituting the rotor portion is inserted into the fixed shaft 1
And a mirror flange 3-2 fixed to the outer periphery of the cylindrical portion 3-1 via a material having a Young's modulus smaller than that of the cylindrical portion 3-1.

As a material having a Young's modulus smaller than that of the cylindrical portion, it is preferable to use an adhesive containing a resin as a main component, but not limited to this, an appropriate material having an adhesive function can be used. . The invention according to claim 2 is the stator core 7 in which the housing 2-1 and the electromagnetic coil are wound.
And a rotary polygonal mirror 11 having a stator portion having at least the fixed shaft 1 and a plurality of reflecting mirror surfaces 11-1 formed on the outer circumference.
And a magnet yoke 5 for supporting the rotating magnets 6-1 and 6-2, and a rotor portion having at least a rotating sleeve 3 for fixing the rotor yoke. In an optical deflector supported by an air bearing, a rotating sleeve 3 forming the rotor portion is inserted into the fixed shaft 1, an inner cylindrical portion 3-3, and a mirror flange 3 for fixing the rotating polygon mirror 11 to the outer periphery. -4, and the outer cylinder part 3-5 having the outer cylinder part 3-5, and the outer cylinder part 3-5 is crimped and fixed to the outer circumference of the inner cylinder part 3-3.

According to the third aspect of the present invention, a stator portion having at least the housing 2-1 and the stator core 7 around which the electromagnetic coil is wound and the fixed shaft 1, and a plurality of reflecting mirror surfaces 11-1 are provided on the outer circumference. The rotor part includes at least a rotating sleeve 3 for fixing the formed rotating polygon mirror 11 and a magnet yoke 5 supporting the rotating magnets 6-1 and 6-2, and the rotor part is attached to the fixed shaft 1 of the stator part. In the optical deflector in which the sleeve 3 of FIG. 3 is supported by a dynamic pressure air bearing, the rotary sleeve 3 that constitutes the rotor section.
Is composed of an inner cylinder portion 3-3 which is inserted through the fixed shaft 1 and an outer cylinder portion 3-5 which has a mirror flange 3-4 which fixes the rotary polygon mirror 11 on the outer circumference. 5 is fixed only in the vicinity of both ends of the inner cylindrical portion 3-3 in the rotation axis direction.

The present invention is not limited to the fixed shaft type in which the shaft of the bearing is fixed, but is a rotary shaft type dynamic pressure air in which the sleeve side is a fixed member and the rotary polygon mirror is fixed to the rotary shaft inserted and attached to this. It goes without saying that the same can be applied to an optical deflector having a bearing. Further, the present invention is not limited to a so-called inner rotor type scanner motor in which a rotating magnet is arranged on the inner circumference of a stator core, but an optical deflection having a so-called outer rotor type scanner motor in which a rotating magnet is arranged on the outer circumference of a stator core. Can also be applied to vessels,
Further, it can be similarly applied to a driving motor other than the optical deflector.

[0031]

According to the structure of the first aspect of the invention, the material interposed between the cylindrical portion 3-1 and the mirror flange 3-2 constituting the rotary sleeve 3 functions as an elastic cushioning material, and the rotary polygon mirror at high speed. It is possible to prevent the inner diameter of the cylindrical portion 3-1 from expanding due to the centrifugal force caused by the rotation, and to avoid a decrease in the rigidity of the dynamic pressure air bearing.

As a result, it is possible to eliminate the deterioration of the rotation accuracy at the time of high speed rotation and the occurrence of vibration due to the deterioration of the rotation accuracy. Further, according to the configuration of the invention of claim 2, the centrifugal force applied to the outer cylinder portion 3-5 having the mirror flange 3-4 does not reach the inner cylinder portion 3-3, and the rotary polygon mirror 11 is rotated at a high speed. It is possible to prevent the inner diameter of the inner cylindrical portion 3-3 from expanding, and to avoid a decrease in the rigidity of the dynamic pressure air bearing.

As a result, it is possible to prevent the deterioration of the rotation accuracy at the time of high speed rotation and the occurrence of vibration due to the deterioration of the rotation accuracy. Further, according to the configuration of the invention of claim 3, the centrifugal force applied to the outer tubular portion 3-6 having the mirror flange 3-4 is generated in the space between the door-attached outer tubular portion 3-6 and the inner tubular portion 3-5. Since it is buffered, it does not reach the inner cylindrical portion 3-5, and the rotary polygon mirror 1
At the time of high speed rotation of No. 1, the inner diameter of the inner cylindrical portion 3-5 is prevented from widening, and the reduction in rigidity of the dynamic pressure air bearing is avoided.

As a result, it is possible to eliminate the deterioration of the rotation accuracy at the time of high speed rotation and the occurrence of vibration due to the deterioration of the rotation accuracy.

[0035]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional view for explaining one embodiment of an optical deflector according to the present invention, in which 1 is a fixed shaft, 1-1 is a groove for generating dynamic pressure, 2-1 is a housing, and housing adapters 2-2 and 3 are shown. Is a rotary sleeve composed of a cylindrical portion 3-1 and a mirror flange 3-2, 5 is a magnet yoke, 6 is a magnet composed of an inner magnet 6-1 and an outer magnet 6-2, 7 is a stator core, 8-1, 8-2
Is a stud, 9 is a circuit board, 10 is a magnetic detection element, 11
Is a rotating polygon mirror, 11-1 is a reflecting mirror surface, 12 is a cap flange, 13, 16, 17, 18, and 20 are screws, 15 is a gap, 21 is a collar, 22 is a damper, 23 is an air pocket, and 24 is a fine hole. , 25 are adhesives.

This optical deflector has its axis 1 fixed, and this axis 1
The sleeve inserted into the rotary shaft is of a fixed shaft type. Here, the shaft 1 is a fixed shaft and the sleeve 3 is a rotary sleeve. The rotary polygon mirror 11 fixed to the rotary sleeve 3 and the magnet 6 held by the magnet yoke 5 are used. -1, 6-
The member consisting of 2 is used as the rotor portion. Note that FIG.
2 is a plan view of an essential part showing the positional relationship between the magnet and the rotary sleeve in FIG.
-2 are arranged concentrically inside and outside the rotary sleeve 7.

In FIGS. 1 and 2, one end of the fixed shaft 1 is fixed to the housing 2-1 and the housing 2-1 is fixed to the housing adapter 2-2 with the screw 16. On the peripheral surface of the fixed shaft 1, a dynamic pressure generating groove 1-1 that functions as a radial bearing is provided. This radial bearing is a bearing for preventing the center of rotation from deviating from a predetermined position even when a force acts in a direction perpendicular to the axial direction.

The rotor portion constituting the scanner motor is a portion inserted into the fixed shaft 1 with a gap 15 therebetween, and the rotary sleeve 3 and the magnet yoke 5 and the magnet yoke fixed to the rotary sleeve 3 by adhesion or shrink fitting. It is composed of magnets 6-1, 6-2 fixed to 5, a rotary polygon mirror 11 fixed to a mirror flange 3-1 constituting the rotary sleeve 3, and a cap flange 12.

On the other hand, the stator portion constituting the scanner motor has a housing 2-1, a fixed shaft 1 fixed to the housing 2-1, and screws 1 for the studs 8-1, 8-2.
7. Magnetic detection suitable for a stator core 7 fixed to the housing 2 with a screw 18 and a hall element installed on the circuit board 9 by winding an electromagnetic coil suitable for the toroidal type together with the circuit board 9 held by 7. It is composed of the element 10 and the like.

Magnets 6-1 and 6-2 forming a so-called scanner motor section for rotating the rotary polygon mirror 11 are permanent magnets. As shown in FIG. 2, a quadrupole magnetized annular magnet is used as a stator core. A magnetic attraction force is exerted between the stator core 7 and the stator core 7, which are arranged on the inner circumference and the outer circumference of the stator 7. This attraction force is generated by the magnets 6-1 and 6-2.
And the opposing position of the stator core 7 do not shift in the axial direction (thrust direction) of the motor. That is, when the magnets 6-1 and 6-2 move to the right, a component that pulls back to the left appears in the attraction force and is pulled back, and when the magnets 6-1 and 6-2 move to the left, a component that pulls back to the right appears and pulls back. Be done. Thus, the magnet 6-
1, 6-2 and the stator core 7 are made to oppose at a predetermined axial position by the magnetic attraction force. That is, the magnets 6-1 and 6-2 and the stator core 7 constitute a magnetic thrust bearing.

As the magnetic detecting element 10, for example, a Hall element is used. This is a magnet 6-
By detecting the leakage magnetic flux of No. 2, it is detected whether the N pole or the S pole has passed when the magnet 6-2 rotates. The detection signal of the magnetic detection element 10 is sent to a control circuit unit (not shown) through the wiring printed on the circuit board 9. The control circuit section determines the direction of the current flowing through the electromagnetic coil wound around each part of the stator core 7 based on this detection signal. As a result, the interaction between the magnets 6-1 and 6-2 and the stator core 7 generates a force in the direction of continuing the rotation.

When the rotary sleeve 3 rotates, the dynamic pressure generating groove 1-1 creates a high-pressure air layer around the shaft 1 (the gap 15). This pressure forms a dynamic air bearing in which the rotary sleeve 3 is supported in a state of floating above the shaft 1. In the figure, the dynamic pressure generating groove 1-
Although 1 is provided on the outer circumference of the fixed shaft 1, a dynamic pressure generating groove 1-1 may be provided on the inner wall of the rotary sleeve 3 instead of this.

The air layer in the gap 15 functions to keep the center of rotation of the rotor part constant. For example, if the rotary sleeve 3 is displaced to the left in the figure, the gap of the gap 15 on the right becomes large, and the pressure in the gap in this portion becomes smaller than that before the displacement. On the other hand, since the gap on the left side is small, the pressure in the gap in this part is larger than that before the gap. When the magnitude relation of the pressure is as described above, the rotary sleeve 3 is pushed rightward and finally returned to the original position.

The rotary sleeve 3 is composed of a cylindrical portion 3-1 which is inserted into the shaft 1 and a mirror flange 3-2 fixed to the cylindrical portion with an adhesive 25. In addition, this cylindrical portion 3-
A yoke 5 is fixed to 1 by fixing with an adhesive, press fitting, shrink fitting, or the like. In such a configuration, when the rotary polygon mirror 11 rotates and the number of rotations increases, the centrifugal force causes the mirror flange 3-2 to expand and deform in the radial direction due to its mass to expand the inner diameter. As a result, tensile stress acts on the adhesive 25 interposed between the inner cylindrical portion of the rotary sleeve 3 and the mirror flange 3-2.

The Young's modulus of the adhesive 25 depends on the mirror flange 3
Since it is smaller than that of -2, it is accompanied by elongation and becomes an elastic buffer, so that only the volume is largely deformed. The deformation of the adhesive 25 reduces the stress applied to the adhesive 25. As a result, a tensile stress to the extent that the inner diameter of the rotary sleeve 3 is widened is less likely to be generated in the cylindrical portion 3-1, and expansion of the gap 15 with the fixed shaft 1 is prevented.

Therefore, it is possible to suppress the deterioration of the rigidity of the dynamic pressure air bearing, maintain a highly accurate rotation, and prevent vibration from occurring. 3 is a cross-sectional view for explaining another embodiment of the optical deflector according to the present invention, the same reference numerals as those in FIG. 1 correspond to the same parts, 3-3 is an inner cylindrical portion, 3-4 is a mirror flange, 3-
5 is an outer cylinder part.

In the figure, the rotor portion is a cylindrical inner cylindrical portion 3-3 and an outer cylindrical portion 3-5 having a mirror flange 3-4.
Rotating sleeve 3 consisting of, rotating polygon mirror 11 fixed to the mirror flange 3-4 with screws 13, magnets 6-1 and 6
-2 attached to the magnet yoke 5.
The outer cylinder portion 3-5, to which the rotary polygon mirror 11 and the yoke 5 are fixed,
It is fixed to the outer periphery of the inner cylindrical portion 3-3 by a fixing means such as press fitting or shrink fitting.

In the above structure, when the rotary sleeve rotates, centrifugal force is generated by the mass of the rotary polygon mirror 11 and the like. Due to this centrifugal force, the outer cylinder portion 3-5 expands and deforms in the radial direction. However, since the inner tubular portion 3-3 is a separate component from the outer tubular portion 3-5, this deformation does not occur. Therefore, there is no change in the gap 15 between the inner cylindrical portion 3-3 and the fixed shaft 1,
Since the inner diameter does not increase, the decrease in rigidity of the dynamic pressure air bearing is suppressed.

Therefore, it is possible to suppress the decrease in rigidity of the dynamic pressure air bearing, maintain highly accurate rotation, and prevent vibration. FIG. 4 is a cross-sectional view for explaining still another embodiment of the optical deflector according to the present invention. The same reference numerals as those in FIGS. 1 and 2 correspond to the same parts, and 3-3 is an inner cylindrical part, 3-4. Is a mirror flange, 3-5 is an outer cylinder portion, and 3-6 and 3-7 are fixed portions.

In the figure, the inner cylinder portion 3-3 and the outer cylinder portion 3-
5 is fixed at both ends of the inner cylindrical portion 3-3 or at two locations in the vicinity thereof by fixing means such as press fitting, shrink fitting or adhesion, or welding, and the two are separated from each other in the intermediate portion. In this configuration, the outer cylinder portion 3-is generated by the centrifugal force generated by the rotation of the rotor portion.
Reference numeral 5 expands and deforms in the intermediate portions of the fixed portions 3-6 and 3-7 with the inner tubular portion 3-3, but does not reach the inner tubular portion 3-3. Therefore, the gap 15 between the inner cylindrical portion 3-3 and the fixed shaft 1 does not change and the inner diameter thereof does not increase, so that the reduction in rigidity of the dynamic pressure air bearing is suppressed.

Therefore, it is possible to suppress the decrease in rigidity of the dynamic pressure air bearing, maintain highly accurate rotation, and prevent vibration.

[0052]

As described above, according to the present invention,
It is possible to prevent the inner diameter of the rotating sleeve from expanding due to the centrifugal force due to the rotation of the rotor part, and to reduce the rigidity of the dynamic pressure air bearing.
It is possible to avoid deterioration of the rotation accuracy of the rotor portion at high speed rotation and generation of vibration due to the decrease.

Not only the optical deflector but also peripheral devices such as a laser oscillator and an optical lens are prevented from deteriorating in performance.
It is possible to provide an optical deflector which can maintain its performance and reliability and can be used in a wide range of rotation regions from low speed rotation to high speed rotation. Note that the present invention is not limited to the one in which the dynamic pressure air bearing described in the embodiment is adopted as the rotating shaft,
It goes without saying that the present invention can also be applied to an optical deflector adopting a static pressure air type or fluid type bearing mechanism.

[Brief description of drawings]

FIG. 1 is a sectional view illustrating an embodiment of an optical deflector according to the present invention.

FIG. 2 is a plan view showing essential parts of a magnet and a rotary sleeve portion in an embodiment of an optical deflector according to the present invention.

FIG. 3 is a sectional view illustrating another embodiment of the optical deflector according to the present invention.

FIG. 4 is a sectional view for explaining still another embodiment of the optical deflector according to the present invention.

FIG. 5 is an explanatory diagram of a schematic configuration of an image recording device using an optical deflector.

FIG. 6 is a cross-sectional view illustrating the structure of an example of a conventional optical deflector.

FIG. 7 is an explanatory diagram of an optical deflector and its operation.

FIG. 8 is a cross-sectional view of an optical deflector similar to FIG. 6 for schematically explaining the problems in the above-mentioned conventional technique.

[Explanation of symbols]

1 ... Fixed shaft, 1-1 ... Groove for dynamic pressure generation, 2-
1 ... Housing, 2-2 Housing adapter, 3
.... Rotating sleeve, 3-1 .... Cylindrical part, 3-2
・ ・ ・ Mirror flange, 3-3 ・ ・ ・ Inner cylinder part, 3-
4 ... Mirror flange, 3-5 ... Outer cylinder part, 3
-3 ... Inner cylinder part, 3-6, 3-7 ... Fixed part, 5 ... Yoke, 6 ... Magnet, 6-1
.... Inner magnet, 6-2 ... Outer magnet, 7 ... Stator core, 8-1, 8-2
.... Studs, 9 ... Circuit boards, 10 ...
Magnetic detection element, 11 ... Rotating polygon mirror, 11-1 ...
..Reflecting mirror surface, 12 ... Cap flanges, 13,
16, 17, 18, 20 ... ・ Screw, 15 ・ ・ ・ ・ ・ ・ Gap, 21 ・ ・ ・ ・ Collar, 22 ・ ・ ・ ・ Damper, 23
・ ・ ・ ・ Air pockets, 24 ・ ・ ・ ・ Micropores, 25 ・ ・ ・
·adhesive.

Claims (3)

[Claims] 1. A stator, which includes at least a housing, a stator core around which an electromagnetic coil is wound, and a fixed shaft, a rotary polygon mirror having a plurality of reflecting mirror surfaces formed on its outer periphery, and a magnet yoke for supporting a rotary magnet. An optical deflector comprising a rotor part having at least a rotating sleeve, wherein a fixed shaft of the stator part supports the rotating sleeve of the rotor part with a dynamic pressure air bearing, wherein the rotating sleeve constituting the rotor part is: An optical deflector comprising a cylindrical portion that is inserted through the fixed shaft and a mirror flange that is fixed to the outer periphery of the cylindrical portion through a material having a Young's modulus smaller than that of the cylindrical portion. 2. A stator, which comprises at least a housing, a stator core around which an electromagnetic coil is wound, and a fixed shaft, a rotary polygonal mirror having a plurality of reflecting mirror surfaces on its outer periphery, and a magnet yoke for supporting a rotary magnet. An optical deflector comprising a rotor part having at least a rotating sleeve, wherein a fixed shaft of the stator part supports the rotating sleeve of the rotor part with a dynamic pressure air bearing, wherein the rotating sleeve constituting the rotor part is: It is composed of an inner cylinder part that is inserted through the fixed shaft and an outer cylinder part that has a mirror flange that fixes the rotary polygon mirror on the outer periphery, and the outer cylinder part is crimped to the outer periphery of the inner cylinder part. And an optical deflector. 3. A stator, which comprises at least a housing, a stator core around which an electromagnetic coil is wound, and a fixed shaft, a rotary polygon mirror having a plurality of reflecting mirror surfaces formed on its outer periphery, and a magnet yoke for supporting a rotary magnet. An optical deflector comprising a rotor portion having at least a rotating sleeve, wherein a sleeve of the rotor portion is supported by a dynamic air bearing on a fixed shaft of the stator portion, wherein the rotating sleeve constituting the rotor portion is It is composed of an inner cylinder part that is inserted through the fixed shaft and an outer cylinder part that has a mirror flange that fixes the rotating polygon mirror on the outer periphery, and the outer cylinder part is fixed only near both ends of the inner cylinder part in the rotation axis direction. An optical deflector characterized in that