JP2000184653A - Motor with hydrodynamic air bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor with a hydrodynamic air bearing wherein no life is shortened or resistance, etc., occurs at start-up even when the orientation of a rotation shaft is other than vertical direction. SOLUTION: A shaft 14 on fixed side and a sleeve 40 on rotation side constitute a hydrodynamic air bearing. A plurality of straight grooves 24 extending in axial direction are formed on the shaft 14 provided horizontally while no straight groove 24 is provided at the top part of the shaft 14. While the sleeve 40 is not rotated, the inside surface of the sleeve 40 contacts the top part of the shaft 14, not contacting the edge of the straight groove 24. The shaft 14 contacts the sleeve 40 for a short period between stopped state and low-speed rotation, however, the inside surface of the sleeve 40 does not contact the edge of the straight groove 24 of the shaft 14 so a rotational resistance is less, getting to a specified rotation in a short time. Since the inside surface of the sleeve 40 does not contact the edge of the straight groove 24, the inside surface of the sleeve 40 does not wear in an early stage, resulting in long life.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure air bearing motor, and more particularly, to a method of supporting a rotating body in a non-contact manner by the pressure of air generated between a shaft and a sleeve which rotate relative to each other. TECHNICAL FIELD The present invention relates to a dynamic pressure air bearing motor provided with a dynamic pressure air bearing that can be used.

[0002]

2. Description of the Related Art In a digital image forming apparatus, generally,
An image is read by scanning an image carrier with a light beam such as a laser from a light source and reading the image, or by scanning a recording medium with a light beam modulated by an image signal or a character signal to record an image.

Among them, as a means for scanning the light beam, an optical deflector comprising a rotary polygon mirror having a plurality of reflection surfaces on its outer periphery and a drive motor for rotating the polygon mirror is used. ing.

[0004] As this type of optical deflector, there is provided a rotating bearing which is preferably a dynamic pressure air bearing or a ball bearing having one of a sleeve and a shaft fitted to each other as a rotating member and the other as a fixed member, and a rotating bearing. A drive motor that generates rotational torque by a magnetic circuit formed by winding an electromagnetic coil around a permanent magnet mounted on a member and an annular core disposed on a fixed member, and a magnetic bearing that holds a rotating body in an axial direction. Things are known.

FIG. 9 is a view for explaining a schematic configuration of an optical deflector and image recording in the image forming apparatus.
0 is a drive motor, 102 is a rotary polygon mirror, 104 is a laser oscillator, 106 is a colletor lens, 108 is a condensing optical system, and 110 is a recording member.

In FIG. 9, a rotary polygon mirror 102 is rotated in the direction of arrow A by a drive motor 100.

[0007] A light beam emitted from a laser oscillator 104 such as a semiconductor laser or a gas laser is modulated by an image signal or the like by a modulator (not shown), and is incident on a reflection surface of a rotary polygon mirror 102.

The light beam reflected by the reflecting surface is projected on a recording member 110 through a condensing optical system 108.

The reflected light beam is deflected in the direction of arrow B as the rotary polygon mirror 102 rotates in the direction of arrow A, and scans the recording member 110 in the main direction. At the same time, the recording member 110
The sub-scanning is performed by the rotation in the direction of arrow C of FIG.
Two-dimensional image writing is performed on 10.

FIG. 10 shows a schematic configuration of a conventional optical deflector.

In FIG. 10, 14 is a shaft, 23 is a groove for generating dynamic pressure (so-called herringbone groove), 40 is a sleeve, 42 is a pedestal, 48 is a rotary polygon mirror, 22 is a rotary driving permanent magnet, and 58 is a rotary driving permanent magnet. Rotating-side permanent magnet, 38 is a fixed-side permanent magnet, 50 is a spring, 57 is a rotation-speed detecting permanent magnet, 18 is a circuit board, 20 is a driving coil, 21 is a magnetic pole detecting element,
8 is a yoke.

The shaft 14 has a permanent magnet 22 for rotational drive, a permanent magnet 57 for detecting the number of revolutions, a pedestal 42, a polygon mirror 48,
A rotating body composed of the rotating side permanent magnet 58 and the like is freely inserted through a sleeve 40 at a bearing interval (a slight gap between the shaft 14 and the sleeve 40).

A pedestal 42 is fixed to the outer periphery of the soub 40, and a rotary polygon mirror 48 is fitted into the pedestal 42 and a spring 50
Has been fixed by.

A search coil (not shown) for detecting the number of rotations is formed on the upper surface of the circuit board 18 opposite to the permanent magnet 57 for detecting the number of rotations, and a plurality of drive coils 20 and a plurality of magnetic pole detection elements 21 are arranged. Have been.

The shaft 14 having the groove 23 for generating dynamic pressure and the sleeve 40 constitute a dynamic pressure bearing. The rotating body is supported radially on the shaft 14 by the groove for generating dynamic pressure. It is performed in a non-contact manner by a dynamic pressure action of air generated in a bearing interval between the rotating sleeve 23 and the rotating sleeve 40.

The magnetic circuit required for rotation is formed between the rotation driving permanent magnet 22 and the yoke 28.

The rotation can be obtained by detecting a plurality of magnetic poles of the rotation driving permanent magnet 22 with the magnetic pole detecting element 21 and energizing the drive coil 20 by predetermined timing logic.

At this time, as the rotation speed, a fluctuation component of the frequency of the voltage induced in the fixed-side rotation speed detection search coil (not shown) by the rotation speed detection permanent magnet 57 is used as a detection signal. Is controlled to be constant.

The rotating body is supported axially between the rotating permanent magnet 58 which is magnetized in the axial direction and the fixed permanent magnet 38 which is magnetized in the opposite direction to the rotating permanent magnet 58. This is done by a suction force. In addition, there are a method of using a magnet and a magnetic material, and a method of floating by a dynamic pressure action of air.

In these conventional dynamic pressure air bearings using a herringbone groove, the shaft 14 is vertical (the direction of gravitational action; the direction of arrow E in FIG. 10) as shown in FIG. Used in posture.

However, as the size and cost of the machine have been reduced, there has been a demand for further reducing the cost of the optical deflector and for using the optical deflector in a horizontal posture (the axis 14 is in the horizontal direction).

As one method for realizing cost reduction, a dynamic pressure bearing having a linear groove, which can reduce the processing cost of the bearing, has been said to be suitable.

Conventional hydrodynamic bearings having a straight groove as a shaft include:
JP-A-8-338960 and the like.

[0024]

However, FIG.
As shown in FIG. 5, when the dynamic pressure bearing composed of the fixed shaft 14 having the linear groove 24 and the rotating sleeve 40 is used in a lateral posture, that is, when the rotating shaft is directed in a direction other than the vertical direction, the linear groove 24 14 in the antigravity direction (arrow D direction).

In this case, unlike the conventional herringbone groove, the life of the bearing and the start-up time are reduced due to the line contact between the edge portion 24A of the linear groove 24 and the sleeve 40 by the rotating body and the pressure of the groove portion. There was a problem.

For example, when the motor is stopped, as shown in FIG.
Is on the top of the shaft 14 on which is formed.

Further, when the motor is started and stopped, the dynamic pressure is low during low-speed rotation, so that the sleeve 40 slides at the edge portion 24A of the linear groove 24 and becomes a resistance. In addition, the sliding of the sleeve 40 at the edge portion 24A of the linear groove 24 leads to the sleeve 40 being worn early.

The present invention has been made to solve the above-mentioned problems, and has a simple structure. Even when the rotating shaft is used in a direction other than the vertical direction, the life is shortened and the resistance at the time of starting is reduced. It is an object of the present invention to provide a hydrodynamic air bearing motor that does not cause the occurrence.

[0029]

According to a first aspect of the present invention, there is provided a hydrodynamic air bearing comprising a sleeve, and a shaft having a plurality of axially extending linear grooves on an outer peripheral surface and inserted into the sleeve. A rotation drive magnet attached to the sleeve side, a drive coil attached to the shaft side,
A dynamic pressure air bearing motor that fixes the shaft and rotates the sleeve, wherein the axial direction of the dynamic pressure air bearing is other than the vertical direction, and the top of the shaft in the antigravity direction includes the It is characterized in that no straight grooves are arranged.

Next, the operation of the hydrodynamic air bearing motor according to the first aspect will be described.

When the sleeve is not rotating, the sleeve is supported by the shaft with the upper portion of the inner peripheral surface in contact with the top of the shaft where the straight groove is not formed.

When a voltage is applied to the drive coil and a current flows, the magnetic field of the rotary drive magnet facing the drive coil and the above current act on the electromagnetic induction to generate a rotary drive force on the rotary drive magnet. With this rotational driving force, the sleeve starts rotating with respect to the shaft.

When the sleeve starts rotating, a dynamic pressure is generated between the shaft and the sleeve, and the dynamic pressure increases as the rotation increases, and the sleeve is eventually supported by the shaft in a non-contact manner.

At the time of start-up, that is, at the time of low-speed rotation from the stop, the shaft and the sleeve are in contact with each other for a short time, but the inner surface of the sleeve does not contact the linear groove formed on the shaft. The rotation resistance is small, and the predetermined rotation can be reached in a short time.

Further, since the inner surface of the sleeve does not come into contact with the linear groove formed on the shaft, the inner surface of the sleeve does not wear out early and has a long life.

According to a second aspect of the present invention, in the dynamic air bearing motor according to the first aspect, the number of the linear grooves arranged on one side with respect to a vertical line passing through the axis of the shaft and the other are provided. The linear grooves are arranged so that the number of the linear grooves arranged in the linear groove is the same or one difference.

Next, the operation of the dynamic air bearing motor according to the second aspect will be described.

Since the dynamic pressure is reduced in the linear groove portion, the number of the linear grooves arranged on one side and the number of the linear grooves arranged on the other side are the same with respect to the vertical line passing through the axis of the shaft. Alternatively, when the linear grooves are arranged so as to have one difference, the distribution of the dynamic pressure does not become uneven. It is more preferable to arrange the straight grooves symmetrically with respect to a vertical line passing through the axis of the shaft.

According to a third aspect of the present invention, in the hydrodynamic air bearing motor according to the first aspect, when the total number of the linear grooves is an even number, the linear groove is positioned above a horizontal line passing through the axis of the shaft. The linear grooves are arranged so that the number of linear grooves arranged and the number of linear grooves arranged on the lower side are the same, and when the total number of linear grooves is odd, one linear groove is The straight line is arranged below the axis and on a vertical line passing through the axis, and the number arranged above and the number arranged below the horizontal line passing through the axis become one difference. It is characterized in that grooves are arranged.

Next, the operation of the hydrodynamic air bearing motor according to the third aspect will be described.

Since the dynamic pressure is reduced in the linear groove portion, when the total number of the linear grooves is even, the number of the linear grooves arranged above and below the horizontal line passing through the axis of the shaft is arranged. By arranging the linear grooves so that the number of the linear grooves is the same as that of the linear grooves, the distribution of the dynamic pressure is not biased.

On the other hand, when the total number of linear grooves is an odd number, one linear groove is arranged below the axis of the shaft and on the vertical line, and the number of linear grooves arranged above the horizontal line passing through the axis and the lower When the linear grooves are arranged so that the number of the grooves is one, the distribution of the dynamic pressure is not biased.

It is more preferable to arrange the straight grooves symmetrically with respect to a vertical line passing through the axis of the shaft.

According to a fourth aspect of the present invention, there is provided a hydrodynamic air bearing including a sleeve having a plurality of axially extending linear grooves on an inner peripheral surface, a shaft inserted into the sleeve, A dynamic pressure air bearing motor, comprising: a rotation driving magnet to be mounted; and a drive coil to be mounted on the sleeve side, the dynamic pressure air bearing motor fixing the sleeve and rotating the shaft, wherein the axial direction of the dynamic pressure air bearing is vertical. It is characterized in that the straight groove is not arranged below the sleeve in the direction of gravity other than the direction.

Next, the operation of the dynamic pressure air bearing motor according to the fourth aspect will be described.

When the shaft is not rotating, the shaft is supported by the shaft with the lower portion of the inner peripheral surface contacting the bottom of the sleeve where the straight groove is not formed.

When a voltage is applied to the drive coil and a current flows, the magnetic field of the rotary drive magnet facing the drive coil and the above-mentioned current act on the electromagnetic induction to generate a rotary drive force on the rotary drive magnet. The shaft starts rotating with respect to the sleeve by this rotational driving force.

When the shaft starts rotating, a dynamic pressure is generated between the shaft and the sleeve, and the dynamic pressure increases as the rotation increases, and the shaft is supported by the sleeve in a non-contact manner.

At the time of start-up, that is, at the time of low-speed rotation from the stop, the shaft and the sleeve are in contact with each other for a short time, but the outer peripheral surface of the shaft does not contact the linear groove formed in the sleeve. In addition, the rotation resistance is small, and a predetermined rotation can be reached in a short time.

Further, since the outer peripheral surface of the shaft does not come into contact with the linear groove formed in the sleeve, the outer peripheral surface of the shaft does not wear out at an early stage, and the life is extended.

According to a fifth aspect of the present invention, in the dynamic air bearing motor according to the fourth aspect, the number of linear grooves arranged on one side with respect to a vertical line passing through the axis of the sleeve shaft is determined. The linear grooves are arranged so that the number of linear grooves arranged on the other side is the same or one difference.

Next, the operation of the hydrodynamic air bearing motor according to the fifth aspect will be described.

Since the dynamic pressure is reduced in the linear groove portion, the number of linear grooves arranged on one side and the number of linear grooves arranged on the other side of the vertical line passing through the axis of the sleeve are the same. Alternatively, when the linear grooves are arranged so as to have one difference, the distribution of the dynamic pressure does not become uneven. It is more preferable to arrange the straight grooves symmetrically with respect to a vertical line passing through the axis of the sleeve.

According to a sixth aspect of the present invention, in the dynamic air bearing motor according to the fourth aspect, when the total number of the linear grooves is an even number, the dynamic groove is positioned above a horizontal line passing through the axis of the sleeve. The linear grooves are arranged so that the number of linear grooves arranged and the number of linear grooves arranged on the lower side are the same, and when the total number of linear grooves is odd, one linear groove is The straight line is arranged above the axis and on a vertical line passing through the axis, and the number arranged above and the number arranged below the horizontal line passing through the axis become one difference. It is characterized in that grooves are arranged.

Next, the operation of the dynamic air bearing motor according to claim 6 will be described.

Since the dynamic pressure is reduced in the linear groove portion, when the total number of the linear grooves is even, the number of the linear grooves arranged above and below the horizontal line passing through the axis of the sleeve is arranged. By arranging the linear grooves so that the number of the linear grooves is the same as that of the linear grooves, the distribution of the dynamic pressure is not biased.

On the other hand, when the total number of the linear grooves is an odd number, one linear groove is arranged below the axis of the sleeve and on the vertical line, and the number arranged above the horizontal line passing through the axis and the lower When the linear grooves are arranged so that the number of the grooves is one, the distribution of the dynamic pressure is not biased.

It is more preferable to arrange the straight grooves symmetrically with respect to a vertical line passing through the axis of the sleeve.

[0059]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the dynamic air bearing motor of the present invention will be described with reference to FIGS.

FIG. 1 is a sectional view showing an optical deflector 8 using a hydrodynamic air bearing motor 6 according to one embodiment of the present invention.

In this dynamic pressure air bearing motor 6, a shaft 14 is erected substantially at the center of the housing 12, and the shaft 1
As shown in FIG. 2A, a plurality of linear grooves 24 extending in the axial direction (three in the present embodiment) are provided on the outer peripheral surface portion 4 of FIG.
Is formed.

A circuit board 18 is provided on a flat surface of the housing 12 on the side where the shaft 14 is erected. On the circuit board 18, a plurality of drive coils 20 are arranged at predetermined positions. In addition, a control circuit (not shown) for the drive coil 20 is provided.

Further, a magnetic pole detecting element 21 is fixed on the circuit board 18 substantially at the center of a predetermined drive coil 20, and a plurality of magnetic poles of a rotation driving permanent magnet 22 described later are fixed by the magnetic pole detecting element 21. Is detected, the position of the rotor 16 is detected.

A yoke 28 is formed on the housing 12 at a position corresponding to the surface of the circuit board 18 opposite to the surface on which the drive coil 20 is disposed (under the drive coil 20). It is placed and housed in the shallow groove 30.

Further, a holder 32 formed integrally with the housing 12 is provided on the housing 12, and a fixed permanent magnet formed in a ring shape having a rectangular cross section is provided on the upper portion of the holder 32. Reference numeral 38 is attached by a method such as bonding.

The sleeve 40 of the rotor 16 mounted on the stator 10 thus configured is formed in a hollow cylindrical shape, and the shaft 14 of the stator 10 is inserted through the hollow portion.

The shaft 14 and the sleeve 40 constitute a dynamic pressure bearing. When the sleeve 40 rotates at a high speed, a dynamic pressure is generated in a small gap between the shaft 14 and the sleeve 40.

The dynamic pressure generated between the shaft 14 and the sleeve 40 is, as shown in FIG.
And is lowest near the linear groove 24 (in FIG. 3, the longer the length of the arrow, the higher the pressure.) As shown in FIG. , A ring-shaped pedestal 42 is fixed by shrink fitting, press fitting or the like.

A mounting surface 46 is formed on the upper surface of the pedestal 42, and a rotating polygon mirror 48 is fixed on the mounting surface 46 by a fixing spring 50.

The mounting surface 46 is machined so as to be perpendicular to the axis of the sleeve 40 with high precision.

The rotary polygon mirror 48 is formed in a polygonal column shape.
The side surface is processed so as to be a mirror surface.

A notch 42A is formed in a portion of the pedestal 42 facing the drive coil 20 on the side of the stator 10. The notch 42A is provided in the notch 42A.
Are attached by a method such as bonding.

The rotation driving permanent magnet 22 has a ring shape as a whole, and a step opening peripheral portion 52 having an opening whose inner diameter is increased by one step is formed in the center hole near the stator 10.

The rotation driving permanent magnet 22 has a central angle of 4 degrees.
The N pole and the S pole are magnetized so that adjacent sections have different polarities in each section divided into eight equal parts every 5 degrees.

On the lower surface of the pedestal 42 on the side of the stator 10, there is formed a stepped portion 56 having a rectangular cross section and notched in an annular shape, and a ring-shaped rotation speed detecting permanent magnet 57 is fixed. Permanent magnet 57 for detecting rotation speed of substrate 18
The rotation speed of the rotor 16 is controlled to be constant by using the fluctuation component of the frequency of the voltage induced in the rotation speed detection search coil (not shown) formed on the upper surface portion opposite to the above as the detection signal.

A rotating permanent magnet 58 formed in a ring shape is attached to the upper part of the outer peripheral surface of the pedestal 42 by a method such as bonding.

The rotating permanent magnet 58 is concentric with the fixed permanent magnet 38 and is arranged adjacent to the fixed permanent magnet 38 at a predetermined interval.

The outer peripheral surface of the rotating permanent magnet 58 and the inner peripheral surface of the fixed permanent magnet 38 are mutually magnetized with different polarities so as to exert an attractive force, thereby forming a thrust magnetic bearing. .

In this thrust magnetic bearing, the attraction force acting between the fixed permanent magnet 38 and the rotating permanent magnet 58 causes the rotor 16 in the thrust direction in the sleeve 40 of the rotor 16 to rotate.
We support. (Operation) Next, the operation of the dynamic pressure air bearing motor 6 of the present embodiment will be described.

When the rotor 16 is not rotating, as shown in FIG. 2B, the sleeve 40 is in contact with the top of the shaft 14 and is not in contact with the edge 24A of the straight groove 24. In FIG. 2B, the gap between the sleeve 40 and the shaft 14 is shown large for easy understanding.

When a voltage is applied to each drive coil 20 under the control of a control circuit (not shown) on the circuit board 18, a current flows through each drive coil 20, and a current is applied to the rotation driving permanent magnet 22 facing each drive coil 20. The magnetic field and the current act on each other to generate an electromagnetic induction action, and a rotational driving force is generated for the rotational driving permanent magnet 22. This rotation driving force causes the rotor 16 to start rotating in a predetermined direction.

When the rotor 16 starts to rotate, a dynamic pressure is generated between the shaft 14 and the sleeve 40, and the dynamic pressure increases with an increase in the rotation.
The gap between 0 and the shaft 14 is substantially equally spaced in the circumferential direction. ) Is supported by the shaft 14. Therefore, the rotor 16
Can rotate at high speed.

Here, at the time of startup, that is, at the time of low-speed rotation from the stop, the shaft 14 and the sleeve 4
0, but the inner surface of the sleeve 40 is
Is not in contact with the edge 24A of the linear groove 24, the rotation resistance is small, and the predetermined rotation can be reached in a short time.

Further, since the inner surface of the sleeve 40 does not contact the edge 24A of the linear groove 24 of the shaft 14, the sleeve 4
The inner surface of No. 0 does not wear out early and has a long life.

In this embodiment, three straight grooves 24 are formed in the shaft 14, but the present invention is not limited to this, and four grooves may be formed as shown in FIG. 4, and as shown in FIG. May be formed.

Here, when forming an even number of straight grooves 24 on the shaft 14, the number of the straight grooves 24 arranged on one side with respect to the horizontal line HL passing through the axis of the shaft 14 and the other are arranged. Linear grooves 2 so that the number of linear grooves 24
4 is preferably arranged. If the number of the linear grooves 24 is different between the upper side and the lower side with respect to the horizontal line HL, the distribution of the dynamic pressure is undesirably generated.

When an odd number of straight grooves 24 are formed on the shaft 14, one straight groove 24 is disposed below the axis and on the vertical line VL, and is positioned above the horizontal line HL passing through the axis. It is preferable to arrange the linear grooves 24 so that the number arranged on the lower side and the number arranged on the lower side are one difference so as not to cause a bias in the distribution of dynamic pressure.

In this embodiment, three straight grooves 24 are formed in the shaft 14. However, the present invention is not limited to this, and four straight grooves 24 may be formed as shown in FIG. May be formed.

In the above embodiment, the shaft 14 is fixed and the sleeve 40 is rotated.
A configuration in which the sleeve 40 is fixed and the shaft 14 is rotated may be employed.

In the configuration in which the sleeve 40 is fixed and the shaft 14 is rotated, for example, as shown in FIGS. 6 to 8, a linear groove 25 extending in the axial direction is formed on the inner peripheral surface of the sleeve 40. In this configuration, though not shown, the shaft 14 can be rotated by fixing the sleeve 40 to the drive coil 20 and fixing the shaft 14 to the rotation driving permanent magnet 22.

The sleeve 40 has an even number of straight grooves 2
In the case of forming 5, the number of the linear grooves 25 arranged on the upper side and the number of the linear grooves 25 arranged on the lower side with respect to the horizontal line HL passing through the axis of the sleeve 40 are the same. It is preferable to arrange the straight grooves 24. If the number of the straight grooves 25 is different between the upper side and the lower side with respect to the horizontal line HL, the distribution of the dynamic pressure is undesirably generated.

The sleeve 40 has an odd number of straight grooves 25.
Is formed, one straight groove 25 is arranged above the axis and on the vertical line VL, and the number arranged above and below the horizontal line HL is one difference. This is a preferable mode in which the arrangement is such that the distribution of dynamic pressure is not biased.

[0093]

As described above, in the dynamic pressure air bearing motor of the present invention, since the inner surface of the sleeve does not come into contact with the linear groove formed on the shaft, the rotation resistance is small and the predetermined rotation can be reached in a short time. In addition, there is an excellent effect that the inner surface of the sleeve is not worn out early and has a long life.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an optical deflector using a dynamic pressure air bearing motor according to an embodiment of the present invention.

FIG. 2A is a perspective view of a shaft of a hydrodynamic air bearing motor according to an embodiment of the present invention, and FIG. 2B is a side view of the shaft and the sleeve as viewed from the axial direction.

FIG. 3 is an explanatory diagram showing a distribution of a dynamic pressure generated between a shaft and a sleeve.

FIG. 4 is a side view of a shaft and a sleeve of the dynamic air bearing motor according to another embodiment, as viewed from the axial direction.

FIG. 5 is a side view of a shaft and a sleeve of a hydrodynamic air bearing motor according to still another embodiment as viewed from the axial direction.

FIG. 6 is a side view of a shaft and a sleeve of a hydrodynamic air bearing motor according to still another embodiment viewed from the axial direction.

FIG. 7 is a side view of a shaft and a sleeve of a hydrodynamic air bearing motor according to still another embodiment viewed from the axial direction.

FIG. 8 is a side view of a shaft and a sleeve of a hydrodynamic air bearing motor according to still another embodiment viewed from the axial direction.

FIG. 9 is a perspective view illustrating a positional relationship between an optical deflector and a light condensing optical system in the image recording apparatus.

FIG. 10 is a sectional view showing a configuration of an optical deflector using a conventional dynamic pressure air bearing motor.

FIG. 11 is a side view of a shaft and a sleeve of a conventional dynamic pressure air bearing motor viewed from the axial direction.

[Description of Signs] 6 Dynamic pressure air bearing motor 14 Shaft 20 Drive coil 22 Permanent magnet for rotation drive 24 Linear groove 25 Linear groove 40 Sleeve

Claims (6)

[Claims] A dynamic pressure air bearing comprising a sleeve, a shaft having a plurality of linear grooves extending in the axial direction on an outer peripheral surface thereof, and a shaft inserted into the sleeve; and a rotation driving magnet attached to the sleeve. A drive coil attached to the shaft side, wherein the dynamic pressure air bearing motor for fixing the shaft and rotating the sleeve, wherein the axial direction of the dynamic pressure air bearing is other than a vertical direction, A dynamic air bearing motor, wherein the linear groove is not disposed at the top of the shaft in the antigravity direction. 2. The number of straight grooves arranged on one side and the number of straight grooves arranged on the other side of a vertical line passing through the axis of the shaft are the same or one difference. The dynamic pressure air bearing motor according to claim 1, wherein the linear groove is arranged. 3. When the total number of the linear grooves is an even number, the number of the linear grooves arranged above and the number of the linear grooves arranged below the horizontal line passing through the axis of the shaft are different. The straight grooves are arranged so as to have the same number, and when the total number of the straight grooves is an odd number, one straight groove is arranged below the axis and on a vertical line passing through the axis,
The said straight groove | channel is arrange | positioned so that the number arrange | positioned at the upper side and the number arrange | positioned at the lower side with respect to the horizontal line passing through the said axis may become one difference. Dynamic pressure air bearing motor. 4. A hydrodynamic air bearing comprising: a sleeve having a plurality of linear grooves extending in the axial direction on an inner peripheral surface; a shaft inserted into the sleeve; a rotary drive magnet mounted on the shaft side; A drive coil attached to the sleeve side, wherein the dynamic pressure air bearing motor for fixing the sleeve and rotating the shaft, wherein the axial direction of the dynamic pressure air bearing is other than the vertical direction, A dynamic pressure air bearing motor, wherein the linear groove is not arranged at a lower portion of the sleeve in the direction of gravity. 5. The number of linear grooves arranged on one side and the number of linear grooves arranged on the other side of the vertical line passing through the axis of the sleeve shaft are the same or one difference. 5. The linear groove is arranged in a groove.
2. A dynamic air bearing motor according to claim 1. 6. When the total number of the linear grooves is an even number, the number of the linear grooves arranged above and the number of the linear grooves arranged below the horizontal line passing through the axis of the sleeve are different. The straight grooves are arranged so as to have the same number, and when the total number of the straight grooves is an odd number, one straight groove is arranged above the axis and on a vertical line passing through the axis,
The linear groove is arranged so that the number arranged on the upper side and the number arranged on the lower side with respect to the horizontal line passing through the axis have one difference. Dynamic pressure air bearing motor.