JPH05134203A - Dynamic pressure air bearing type optical deflector - Google Patents

Abstract

PURPOSE:To maintain the bearing rigidity while decreasing the windage loss of a rotary polygon mirror or rotary single-surface mirror in its rotation by sucking air at the outer periphery of a motor rotation part through a hole constituting a dynamic pressure bearing part when the motor rotation part rotates to lower the atmospheric pressure in the optical deflector. CONSTITUTION:A dynamic pressure shaft 1 and a cover member 4 are fixed through an O ring 20 and the cover member 4 and a motor case 3 are fixed through an O ring 21 without any gap. The space in the motor rotation part and the outside are linked to each other through a lengthwise hole (g) formed in the dynamic pressure shaft 1 through the gap between the dynamic pressure shaft 1 and a sleeve 2 and holes (b) and (c) communicating with the hole (g). When a motor part consisting of a yoke 16, a coil 15, a Hall element 18, and a magnet 22 is driven, the sleeve 2 fixed to the magnet 22 rotates and the rotary polygon mirror 5 fixed to a hub 6, fixed to the sleeve 2, with a screw 9 further rotates. At this time, dynamic pressure is generated between the dynamic pressure shaft 1 and sleeve 2 and the bearing rigidity is generated with the dynamic pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to information equipment, image equipment,
The present invention relates to a dynamic pressure air bearing type optical deflector used in a measuring instrument.

[0002]

2. Description of the Related Art The structure and operation of an example of a conventional dynamic pressure air bearing type optical deflector will be described with reference to FIGS.
FIG. 8 is a sectional view of a conventional dynamic air bearing type optical deflector. The dynamic pressure shaft 1a is fixed to the motor case 3 by shrink fitting or the like without any gap. The dynamic pressure shaft 1a and the cover member 4 are fixed to each other via an O-ring 20, and the cover member 4 and the motor case 3 are fixed to each other via an O-ring 21 without any gap.
The Hall element 18 is provided on the support plate 17 that is installed over the opening of the motor case 3. A cylindrical sleeve 2 is fitted and fitted on the outer circumference of the dynamic pressure shaft 1a, and a magnet 22 is fitted and fixed on the outer circumference of the sleeve 2. The magnet 22 is provided in the vertical side wall of the motor case 3 so as to face the sleeve 2. The coil 15 is wound around the yoke 16. A thrust dynamic pressure bearing 12 is provided on the inner wall of the motor case 3 so as to extend over the outer circumference of the dynamic pressure shaft 1 a, and a washer 13 is disposed on the thrust dynamic pressure bearing 12. Reference numeral 14 is provided at the lower end of the magnet 22,
It is a spacer fixed to the washer 13. Cover member 4
A hub 6 fixed to the outer circumference of the sleeve 2 and a rotary polygon mirror 5 horizontally fixed to the hub 6 with screws 9 are housed therein together with the sleeve 2 so that the outer circumference of the dynamic pressure shaft 1a can be rotated.
A pair of thrust suppressing magnets 10 and 11 having different polarities are provided on the upper end of the sleeve 2 and the inner surface of the cover member 4 facing the upper end of the sleeve 2. The space inside the motor rotating portion and the outside communicate with a longitudinal center hole Hg having an inlet K provided in the dynamic pressure shaft 1a, which will be described later, through a gap between the dynamic pressure shaft 1a and the sleeve 2, and to communicate therewith. It circulates through the openings of the holes Hb and Hc. When the coil 15 is energized, the yoke 1
6, the motor drive unit composed of the Hall element 18 and the magnet 22 operates, and the cylindrical sleeve 2 in which the magnet 22 is fitted and fixed is supported by the thrust dynamic pressure bearing 12 on the outer periphery thereof, and the dynamic pressure shaft 1a is used as the core. Rotate. At the same time, together with the hub 6 provided on the outer circumference of the sleeve 2, the rotary polygon mirror 5
Rotates. At this time, a dynamic pressure is generated between the dynamic pressure shaft 1a and the sleeve 2, and this dynamic pressure causes bearing rigidity. An appropriate gap is maintained between the magnets 10 and 11 by the repulsive force of the magnets. The pressure distribution of the air in the gap between the dynamic pressure shaft 1a and the sleeve 2 will be described with reference to FIGS. 9 to 12. FIG. 9 is a plan view of the dynamic pressure shaft 1a, showing a dynamic pressure bearing portion. The dynamic pressure shaft 1a is provided with a pair of dynamic pressure bearing portions Ma including herringbone grooves Hd and He having suction angles β opposite to each other and a groove non-machined portion Hf. FIG. 10 is a cross-sectional view of the upper half of the dynamic pressure shaft 1a. In the longitudinal direction of the central portion of the dynamic pressure shaft 1a, a central hole Hg having an inlet K communicating with the atmosphere and a central hole Hg communicating with the central hole Hg. Hole H that opens in the direction of sleeve 2
b and Hc are drilled. Filter 2 near the entrance K
3 is provided (FIG. 8). The openings of the holes Hb and Hc are located at the centers of the herringbone grooves Hd and He, and the dynamic pressure bearing portion M of the conventional dynamic pressure air bearing type optical deflector shown in FIG.
The boundary condition of a is that the pressure of the air at the openings of the holes Hb and Hc is equal to the atmospheric pressure. Further, in the stable rotation state, as shown in FIG. 11, the mass flow rate in the axial direction becomes 0 at the air suction port, so the pressure distribution in the dynamic pressure bearing portion Ma becomes the state shown in FIG. In FIG. 12, the vertical axis is the dimensionless pressure P with the representative value being atmospheric pressure, and P =
A value of 1 indicates that air pressure is equal to atmospheric pressure. In this conventional example, as shown in FIG. 12, the air intake ports at both ends of the dynamic pressure bearing portion Ma have a pressure lower than the atmospheric pressure. Therefore, the air pressure in the dynamic pressure air bearing type optical deflector shown in FIG. 8 is large. Although it is lower than the atmospheric pressure to reduce the wind loss, the maximum air pressure inside the dynamic pressure bearing portion Ma is the atmospheric pressure as described above.

[0003]

In the conventional dynamic pressure air bearing type optical deflector, the rotary polygon mirror is rotated by the rotation of the motor rotating portion.
Since the atmospheric pressure in the gap between the dynamic pressure shaft and the sleeve is atmospheric pressure in order to reduce the air pressure in the outer periphery of the motor rotating portion including the rotating single-sided mirror and reduce the wind loss of the rotating polygonal mirror or the rotating single-sided mirror, There is a problem that the bearing rigidity becomes low.

[0004]

The present invention has been made to solve the above-mentioned problems, and the outer periphery of a dynamic pressure shaft 1 erected on a case 3 is rotatable together with a rotary polygon mirror 5 or a rotary single-sided mirror. In the optical deflector in which the motor rotating portion is housed in the case 3 and the cover member 4, the herringbone grooves q, d,
A central hole g communicating with the atmosphere is formed in the longitudinal direction of the central portion of the dynamic pressure shaft 1 in which e, d, e, and r are formed, and the herringbone grooves q and r located at both ends and Holes b and c, which communicate with the central hole g and are opened in the gap direction between the dynamic pressure shaft 1 and the sleeve 2, are formed at the center positions of the herringbone grooves d and e located on the inner side to rotate the motor. The pressure of the gap between the dynamic pressure shaft 1 and the sleeve 2 is kept higher than the atmospheric pressure while lowering the atmospheric pressure at the outer periphery of the rotating polygon mirror 5 and the rotating portion of the motor including the rotating single-sided mirror by the rotation of the rotary polygon mirror 5. Alternatively, the bearing rigidity is increased while reducing the windage loss of the rotating single-sided mirror.

[0005]

In the dynamic pressure air bearing type optical deflector of the present invention,
When the motor rotating part rotates, the hole forming the dynamic pressure bearing part sucks air in the outer periphery of the motor rotating part to lower the air pressure inside the optical deflector and at the same time reduce the pressure in the gap between the dynamic pressure shaft and the sleeve from atmospheric pressure. By also increasing, the rigidity can be increased while reducing the windage loss due to the rotary polygon mirror or the rotary single mirror.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a dynamic pressure air bearing type optical deflector according to the present invention will be described below with reference to the accompanying drawings. In this embodiment, a dynamic pressure air bearing type optical deflector equipped with a rotary polygon mirror is described, but it goes without saying that a rotary single mirror may be installed. Among the reference numerals used in the description of the conventional dynamic air bearing type optical deflector, the same members as those in this embodiment indicate the same members. FIG. 1 is a sectional view of a dynamic pressure air bearing type optical deflector according to the present invention. The dynamic pressure shaft 1 is firmly fixed to the motor case 3 by shrink fitting or the like. or,
The dynamic pressure shaft 1 and the cover member 4 are fixed to each other via an O-ring 20, and the cover member 4 and the motor case 3 are fixed to each other via an O-ring 21 without any gap. A space in the motor rotating portion and the outside are passed through a gap between the dynamic pressure shaft 1 and the sleeve 2 and a longitudinal center hole g provided in the dynamic pressure shaft 1 described later and holes b and c communicating with the central hole g. Is distributed through the opening. Yoke 16, coil 15, ..., Hall element 18, magnet 2
When the motor unit composed of 2 is driven, the magnet 2
The hollow cylindrical sleeve 2 to which 2 is fixed rotates, and the rotary polygon mirror 5 fixed to the hub 6 fixed to the sleeve 2 with a screw 9 also rotates. At this time, a dynamic pressure is generated between the dynamic pressure shaft 1 and the sleeve 2, and this dynamic pressure causes bearing rigidity.

The pressure distribution of the air in the gap between the dynamic pressure shaft 1 and the sleeve 2 will be described with reference to FIGS. 2 to 7. FIG. 2 is a sectional view of the dynamic pressure shaft 1, showing a dynamic pressure bearing portion M. In the dynamic pressure shaft 1,
Herringbone groove d with suction angles β opposite to each other
And e and two pairs of hydrodynamic bearings M composed of a groove-unmachined portion f,
M and the suction angle β in the same direction as the herringbone grooves d and e that are located at both ends of the two pairs of dynamic pressure bearings M and M
There are provided herringbone grooves q and r. Further, as shown in FIG. 4, the hydrodynamic bearing M may have only the herringbone grooves d1 and e1 which have been subjected to the entire surface processing without the groove non-processed portion. FIG. 3 is a cross-sectional view of the upper half of the dynamic pressure shaft 1. In the longitudinal direction of the central portion of the dynamic pressure shaft 1, a central hole g having an inlet K communicating with the atmosphere and a central hole g communicating with the central hole g. Sleeve 2
Holes b and c that open in the direction of are formed. A filter 23 is provided near the entrance K. The openings of the holes b and c are
Dynamic bearings M, M and herringbone groove q provided on the outside thereof
And r, which are located at the respective centers, and the boundary condition of the dynamic pressure shaft 1 of the dynamic air bearing type optical deflector according to the present invention shown in FIG. 1 is that the air at the opening portions of the holes b and c is The pressure of is equal to the atmospheric pressure. When the rotation is stable,
As shown in FIG. 7, the mass flow rate in the axial direction is 0 at the air suction port, so the pressure distribution in the dynamic pressure shaft 1 becomes the state shown in FIG. In FIG. 7, the vertical axis represents the dimensionless pressure P whose representative value is atmospheric pressure, and when P = 1, the air pressure is equal to atmospheric pressure. In the present invention, as described above, since the air pressure at the opening portions of the holes b and c located at the centers of the dynamic bearing M and the herringbone grooves q and r becomes equal to the atmospheric pressure, as shown in FIG. The air pressure at the air suction port becomes lower than the atmospheric pressure, and the air pressure inside the dynamic pressure air bearing type optical deflector shown in FIG. 1 also becomes lower than the atmospheric pressure. However, in the gap between the dynamic pressure shaft 1 and the sleeve 2. The maximum air pressure is higher than the atmospheric pressure, and the bearing rigidity can be increased while reducing the wind loss.

[0008]

As described above in detail, according to the present invention,
Since the air pressure inside the dynamic pressure bearing, that is, the gap between the dynamic pressure shaft and the sleeve can be increased while reducing the ambient pressure of the rotating polygon mirror, the bearing rigidity is also reduced when the wind loss is reduced and the motor labor is saved. The performance of the motor can be maintained without causing it.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a dynamic pressure air bearing type optical deflector according to the present invention.

FIG. 2 is a plan view of an embodiment of a dynamic pressure bearing portion of a dynamic pressure air bearing type optical deflector according to the present invention.

3 is a sectional view of the upper half of the dynamic pressure bearing portion of FIG.

FIG. 4 is a plan view of another embodiment of the dynamic pressure bearing portion of the dynamic pressure air bearing type optical deflector according to the present invention.

5 is an upper half sectional view of the dynamic pressure bearing portion of FIG.

6 is a cross-sectional view of a dynamic pressure bearing portion including a sleeve having a herringbone groove illustrated in FIG.

7 is a diagram showing a pressure distribution around a dynamic pressure bearing portion of the dynamic pressure air bearing type optical deflector shown in FIG.

FIG. 8 is a cross-sectional view of a conventional dynamic pressure air bearing type optical deflector.

FIG. 9 is a plan view of a dynamic pressure bearing portion of a conventional dynamic pressure air bearing type optical deflector.

10 is a sectional view of the upper half of the dynamic pressure bearing portion of FIG.

11 is a cross-sectional view of a hydrodynamic bearing portion including a sleeve having a herringbone groove illustrated in FIG.

12 is a diagram showing a pressure distribution around a dynamic pressure bearing portion of the dynamic pressure air bearing type optical deflector shown in FIG.

[Explanation of symbols]

 1 dynamic pressure shaft 2 sleeve 3 motor case 5 rotating polygon mirror 10 thrust suppressing magnet 11 thrust suppressing magnet 12 thrust dynamic pressure bearing 13 washer 15 coil 16 yoke 20 O-ring 21 O-ring 22 magnet 23 filter b hole c hole d herring Bone groove e Herringbone groove d1 Herringbone groove e1 Herringbone groove q Herringbone groove r Herringbone groove f Groove unprocessed part g Central hole K Inlet M Dynamic air bearing part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Rie Wakashima 110-1 Shinkushita Nitta, Iruma City, Saitama Copal Electronics Co., Ltd.

Claims (2)

[Claims] 1. An optical deflector having a case and a cover member in which a motor rotating portion, which is rotatable together with a rotating polygon mirror or a rotating single-faced mirror, is housed on the outer circumference of a dynamic pressure shaft erected on the case, and a herringbone groove is formed on the outer circumference. In the longitudinal direction of the central part of the dynamic pressure shaft that was drilled, a central hole communicating with the atmosphere is drilled, and it is located at the center position of the herringbone groove located on both ends and the herringbone groove located inside it. , A hole communicating with this central hole and opened in the direction of the gap between the dynamic pressure shaft and the sleeve is formed, and the rotation of the motor rotating part causes the pressure on the outer periphery of the rotating part of the motor including the rotating polygon mirror and the rotating single-sided mirror. While maintaining the air pressure in the gap between the dynamic pressure shaft and the sleeve higher than atmospheric pressure while reducing the wind loss of the rotating polygon mirror or rotating single-sided mirror, and increasing the bearing rigidity. Type optical deflector. 2. A plurality of pairs of herringbone grooves having suction angles in directions different from each other are formed on the outer periphery of the dynamic pressure shaft, and further, one herringbone groove is formed on each side end of the plurality of pairs of herringbone grooves. 2. A hydrodynamic air bearing type optical deflector according to claim 1, wherein holes are opened at respective center positions of the herringbone grooves located at both ends of the herringbone grooves and the herringbone grooves which are adjacent to each other. vessel.