JP4514931B2 - Dynamic pressure air bearing type optical deflector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrodynamic air bearing type optical deflector mounted on information equipment, imaging equipment, measuring equipment, etc., and in particular, includes a pump mechanism that can evacuate the inside of a case, and achieves low power consumption and low noise. The present invention relates to a high-performance hydrodynamic air bearing type optical deflector that can be made into a simple structure.
[0002]
[Prior art]
The present applicant is provided with a pump mechanism capable of discharging the air in the case sealed by the case and the cover member to the outside of the case by rotating the rotor portion, and reducing or evacuating the inside of the case. Japanese Patent Application Laid-Open No. 09-061742, Japanese Patent Application Laid-Open No. 10-206780, Japanese Patent No. 2645768, Japanese Patent No. 2645773, Japanese Patent Application No. 11-159539, and the like have been proposed.
A hydrodynamic air bearing type optical deflector including this pump mechanism will be described with reference to FIGS.
[0003]
15 is a longitudinal sectional view showing an example of a hydrodynamic air bearing type optical deflector having a pump mechanism, and FIG. 16 is a half sectional view showing a peripheral portion of the pump mechanism of the hydrodynamic air bearing type optical deflector of FIG. is there.
[0004]
Reference numeral 11h denotes a base having a fixed shaft 21h standing substantially at the center, and a housing 13h to which a stator coil 63 is fixed. A case 15h is formed by surrounding the periphery of the housing 13h.
A rotating shaft 23h rotatably supported by a radial dynamic pressure air bearing 31h is engaged with the outer periphery of the fixed shaft 21h, and a rotary polygon mirror 61, a rotor yoke 65, and the like are attached to the rotating shaft 23h. The part is composed.
By housing this rotor portion in a case sealed by a case 15h comprising a base 11h and a housing 13h and a cover member 17h formed with a laser light transmission window (not shown), the rotor portion is substantially sealed. In the mirror chamber 19h, the rotor portion including the rotary polygon mirror 61 rotates at a high speed.
[0005]
Here, in the dynamic pressure air bearing type optical deflector provided with the pump mechanism, as shown in FIG. 16, the rotor portion rotates to generate dynamic pressure in the radial dynamic pressure air bearing 31h. As shown by the arrows in the figure, the air in the case (mirror chamber 19h) is fixed by the upper and lower pump mechanisms 41h and 43h formed by herringbone grooves carved at both ends of the radial dynamic pressure air bearing 31h. The air is sucked from the atmospheric communication passages 49j and 49k formed toward the substantially central portion of the shaft 21h, and discharged to the outside of the case through the atmospheric communication passage 49i and the filter 53h formed in the approximate central portion of the fixed shaft 21h. As the time elapses, the inside of the case can be decompressed to a substantially vacuum state.
[0006]
Thus, by reducing or evacuating the pressure in the case (mirror chamber 19h), it is possible to greatly reduce the air resistance when the rotor portion rotates, so that it is possible to suppress the loss of the motor, Wind noise generated when the rotating polygonal mirror 61 rotates at high speed can be greatly suppressed.
[0007]
17 to 23 show another configuration example of a dynamic pressure air bearing type optical deflector including a pump mechanism. The dynamic pressure air bearing type optical deflector of FIGS. 17 to 18 is a radial dynamic pressure air. By separately forming a herringbone groove for suction at both ends of the bearing 31i, the bearing rigidity of the radial dynamic pressure air bearing 31i can be increased. The dynamic pressure air bearing type light shown in FIGS. The deflector can suppress the axial dimension by providing the thrust bearings 33j and 33i with a pump function.
Further, FIG. 21 shows that the pump mechanism 43g is provided only at one end of the radial dynamic pressure air bearing 31g, so that the axial dimension can be similarly suppressed. FIG. 23 shows that the hollow sleeve is fixed to the fixed shaft. Although it is 21e, basically the same effect as the dynamic pressure air bearing type optical deflector shown in FIGS. 13 to 14 can be obtained.
22A to 22C show other configuration examples of the radial dynamic pressure air bearing, but not limited to the herringbone groove, various types of dynamic pressure air bearings can be applied. It is.
[0008]
As described above, the dynamic pressure air bearing type optical deflector including the pump mechanism reduces or evacuates the pressure in the case sealed by the case and the cover member to a considerably lower pressure than the atmospheric pressure at the rotation speed of use. Therefore, it is possible to greatly reduce windage loss and wind noise caused by a rotating polygon mirror, and to reduce power consumption.
[0009]
[Problems to be solved by the invention]
However, when air is present in the case, the heat generated by the fluid friction in the radial dynamic pressure air bearing or the like is not conducted to the case or the cover member via the fixed shaft or the like. The temperature around the bearing is almost uniform because it is transmitted (convection) to the case and the cover member as a medium, but almost no convection occurs in the case when the case is depressurized or evacuated. In particular, in a hydrodynamic air bearing type optical deflector equipped with a pump mechanism, a discharge hole is provided in at least a part of the fixed shaft in order to discharge the air in the case to the outside. Since it is exposed to the outside of the case or comes into contact with the outside air, it is easier to radiate heat than other parts.
For this reason, the temperature around the bearing part including the pump mechanism varies, and the difference in temperature appears as a difference in thermal expansion amount. Therefore, the rotary shaft of the radial dynamic pressure air bearing or pump mechanism as the heat generating part The gap between the fixed shaft and the fixed shaft is not uniform throughout the entire bearing portion, and the clearance cannot be ensured, resulting in a decrease in bearing performance, and in the worst case, seizure of the rotating shaft occurs.
[0010]
The present invention provides a dynamic pressure that does not cause a decrease in bearing performance even when a temperature difference occurs across the entire bearing portion, or that makes it difficult to cause a temperature difference throughout the bearing portion, thereby obtaining a stable rotational state. The object is to obtain an air bearing type optical deflector.
[0011]
The objects and novel features of the present invention will become more fully apparent when the following description is read in conjunction with the accompanying drawings. However, the drawings are for explanation only and do not limit the technical scope of the present invention.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is capable of rotating freely with a hollow fixed shaft standing on a case and a radial dynamic pressure air bearing comprising an outer periphery or an inner periphery of the fixed shaft including a herringbone groove and other dynamic pressure generating portions. A rotary polygon mirror or other rotor part that rotates integrally with the rotary shaft, and accommodates the rotor part in a case sealed by a case and a cover member, and the rotor part is rotated by rotating the rotor part. A dynamic pressure air bearing type optical deflector having a pump mechanism for discharging air in a case to the outside of the case and reducing or evacuating the inside of the case, a pump provided in the vicinity of the fixed shaft exposed to the outside of the case The gap between the fixed shaft and rotating shaft of the mechanism is almost constant before and after driving the motor. , Near the exposed part of the fixed shaft In order to change the thickness of the fixed shaft facing the pump mechanism, a notch is provided in which the gap increases toward the lower side of the rotating shaft. Thus, a dynamic pressure air bearing type optical deflector is configured.
[0013]
[0014]
[0015]
[0016]
[0017]
[0018]
Embodiment
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the hydrodynamic air bearing type optical deflector and the present invention, which the present inventors have considered, will be described below in detail with reference to the accompanying drawings.
[0019]
FIG. 1 is a longitudinal sectional view of a first hydrodynamic air bearing type optical deflector considered by the present inventor, and FIG. 2 is an enlarged half section of a main part of the hydrodynamic air bearing type optical deflector of FIG. FIG.
[0020]
Reference numeral 15a denotes a case in which a hollow fixed shaft 21a is erected at a substantially central portion, and a stator coil 63 is fixed to an inner surface thereof.
A shaft of a rotary shaft 23a rotatably supported by a radial dynamic pressure air bearing 31a is engaged with the inner periphery of the hollow fixed shaft 21a. The hub is formed integrally with the shaft to fix the fixed shaft 21a. The rotor portion is configured by covering the open end above the shaft 21a and attaching the rotary polygon mirror 61, the rotor yoke 65, and the like to the outer periphery of the hub.
The rotor portion is housed in a case sealed by a cover member 17a formed with a case 15a and a laser light transmission window (not shown), with the thrust bearing 33a being supported in the thrust direction. Thus, the inside of the mirror chamber 19a sealed at a high speed is rotated at high speed.
[0021]
Here, referring to FIG. 1, the pump mechanism for reducing the pressure in the case (mirror chamber 19a) or making it substantially vacuum will be described in detail. A predetermined clearance is provided between the outer periphery of the rotating shaft 23a and the inner periphery of the fixed shaft 21a. The rotor portion is rotatably supported by a radial dynamic pressure air bearing 31a provided substantially at the center thereof.
Pump mechanisms 41a and 43a, such as herringbone grooves, are provided at both ends of the radial dynamic pressure air bearing 31a, and the inner diameter of the hub of the rotating shaft 23a and the outer diameter of the fixed shaft 21a are opposed to each other. The air in the mirror chamber 19a is sucked in accordance with the rotation of the rotor portion through a communication path 51a that communicates between the gap and the lower end portion of the fixed shaft 21a and the inside of the case formed in the flange portion of the fixed shaft 21a. .
As shown by the arrows in the figure, the sucked air in the mirror chamber 19a is connected to the atmospheric communication passages 49a, 49b, 49c formed in the shaft of the rotary shaft 23a, the lower pump mechanism 43a, and the radial dynamic pressure air bearing. 31a is discharged to the outside of the case through a discharge port 45a formed in the flange portion of the fixed shaft 21a and the filter 53a, which communicates the vicinity of the boundary with the outside, and the interior of the mirror chamber 19a as time passes. The pressure can be reduced or substantially evacuated.
On the other hand, both ends of the radial dynamic pressure air bearing 31a communicate with the outside of the case through the atmosphere communication passages 49a, 49b, 49c, the discharge port 45a, and the like, and these both ends are at atmospheric pressure. Regardless of the pressure inside 19a, a stable bearing rigidity can always be obtained.
[0022]
However, the problem here is that since the inside of the mirror chamber 19a is substantially evacuated, the heat generated by the radial dynamic pressure air bearing can hardly be expected to be radiated by convection, and the fixed shaft 21a and the rotation are exclusively used. The heat is transferred to the outside of the case by the heat conduction of the shaft 23a.
[0023]
This will be described in detail with reference to FIG. 13. Since the flange portion of the fixed shaft 21e is exposed to the outside, heat dissipation is good, and a temperature difference is generated between the vicinity of the exposed portion and the other portions. Thus, a difference in the amount of thermal expansion occurs.
That is, due to thermal expansion caused by fluid friction of the radial dynamic pressure air bearing 31a, the rotary shaft 23a and the fixed shaft 21e are deformed as indicated by broken lines, and the rotary shaft 23a and the fixed shaft 21e face each other. Thus, the initial gap CL1 changes like CL2 and CL3, respectively.
When the temperature of the rotating shaft 23a and the fixed shaft 21e is substantially the same, the gap is almost the same as CL1 and CL2, but when there is a temperature difference between them, the gap is CL3. Is narrower than CL1 and it becomes impossible to secure a predetermined clearance.
It will cause burn-in.
[0024]
On the other hand, in the first hydrodynamic air bearing type optical deflector considered by the present inventor, as shown in FIG. 2, a pump provided near the flange portion of the fixed shaft 21a exposed to the outside. Since the gap between the fixed shaft 21a of the mechanism 43a and the rotary shaft 23a is set to be larger by G than the gap between the fixed shaft 21a and the rotary shaft 23a of the radial dynamic pressure air bearing 31a, the entire bearing portion is used. Even when a temperature difference occurs, it is possible to obtain a stable rotation state without causing deterioration in bearing performance or seizure of the rotating shaft.
[0025]
By the way, the temperature around the radial dynamic pressure air bearing rises by about 55 ° C (when the room temperature is 25 ° C, it becomes about 80 ° C), and the temperature difference between the rotating shaft and the fixed shaft reaches about 20 ° C. When a temperature difference of 20 ° C. occurs when both the rotating shaft and the fixed shaft are formed of aluminum, the linear expansion coefficient of aluminum is 23 to 29E-6 / ° C. (here, “E-6”) Is the meaning of minus 6 to the power, that is, 0.000023 to 0.000029 / ° C., hereinafter the same notation). Therefore, since the gap is considered to change by about 3 μm, G here is 3 μm. Is set.
However, since these data are considered to vary depending on the motor specifications, operating environment, etc., it is desirable to set the G value according to the specifications.
Further, the maximum value of G may be set to such an extent that the pump function can be obtained when the gap between the fixed shaft and the rotating shaft of the pump mechanism is minimized due to the temperature difference.
[0026]
Next, another hydrodynamic air bearing type optical deflector considered by the present inventor will be described with reference to FIGS.
In addition, about the structure same as the 1st dynamic pressure air bearing type | mold optical deflector which this inventor considered, the description is abbreviate | omitted by providing the same code | symbol.
[0027]
FIG. 3 is an enlarged half-sectional view of the main part of the second hydrodynamic air bearing type optical deflector considered by the present inventor.
[0028]
The second hydrodynamic air bearing type optical deflection considered by the present inventor differs from the first hydrodynamic air bearing type optical deflector considered by the present inventor mainly in that the fixed shaft of the lower pump mechanism is The gap with the rotating shaft is not set to be G wider than the gap between the fixed shaft and the rotating shaft of the radial dynamic pressure air bearing, but as shown in Fig. 3, it corresponds to the gap change due to thermal expansion. In other words, it is set wide with a gradient in the range of 0 to G.
[0029]
In this way, by setting the gradient within the range from 0 to G, the optimum clearance can be obtained after the gap between the rotating shaft and the fixed shaft is changed due to thermal expansion. Therefore, more stable bearing performance and pump function can be obtained.
[0030]
4 to 5 are longitudinal sectional views of third and fourth dynamic pressure air bearing type optical deflectors considered by the present inventors.
[0031]
The third and fourth dynamic pressure air bearing type optical deflectors considered by the present inventor are mainly different from the first and second dynamic pressure air bearing type optical deflectors considered by the present inventor in the lower part. Rather than setting the gap between the fixed shaft and the rotary shaft of the pump mechanism wider than the gap between the fixed shaft and the rotary shaft of the radial dynamic pressure air bearing, axial flow generation that generates axial flow in the radial dynamic pressure air bearing The mechanism is provided in the vicinity of the radial dynamic pressure air bearing or integrally with the radial dynamic pressure air bearing, and the air supplied to the axial flow generating mechanism is cooled through a discharge port that discharges it to the outside of the case.
[0032]
4 shows an axial flow generating mechanism 67a provided near the lower end of the radial dynamic pressure air bearing 31b, and FIG. 5 shows an axial flow generating mechanism 67b provided integrally with the radial dynamic pressure air bearing 31c. However, the air supplied to these axial flow generation mechanisms 67a and 67b is cooled through the discharge port 45a formed in the flange portion of the fixed shaft 21e, and this cooled air is cooled by the radial dynamic pressure air bearing 31b, Since the temperature distribution throughout the radial dynamic pressure air bearings 31b and 31c can be equalized when flowing through the 31c, it is the same as the first and second dynamic pressure air bearing type optical deflectors considered by the present inventors. In addition, since the heat generation of the radial dynamic pressure air bearings 31b and 31c can be suppressed, the maximum rotation speed can be increased by about 10%.
[0033]
6 to 7 are longitudinal sectional views of fifth and sixth dynamic pressure air bearing type optical deflectors considered by the present inventors.
[0034]
The fifth and sixth dynamic pressure air bearing type optical deflections considered by the present inventors are mainly different from the third and fourth dynamic pressure air bearing type optical deflections considered by the present inventors. This is because the inlet for supplying air to the axial flow generating mechanism and the outlet for discharging the air to the outside of the case through the radial dynamic pressure air bearing are provided separately.
[0035]
FIG. 6 shows a radial dynamic pressure air bearing 31c in which, instead of providing a lower pump mechanism, a cylindrical end provided with an atmospheric communication passage 49a penetrating the inside is provided on the rotary shaft 23d, and an axial flow generating mechanism is provided integrally. As shown by the arrows in the figure, air is drawn from the outside of the case through the filter 53b of the suction port 47a provided at the substantially central portion of the bottom plate 57b provided at the lower end surface of the fixed shaft 21c. The air is sucked and discharged to the outside of the case through the air communication passage 49a, the radial dynamic pressure air bearing 31c, the discharge port 45a, and the filter 53a.
[0036]
In FIG. 7, the lower pump mechanism 43c and the like remain unchanged, and the flange portion of the fixed shaft 21d opens near the boundary between the suction port 47b and the discharge port 45b, and the upper end surface of the upper pump mechanism 41a and the radial dynamic pressure air bearing 31c. Provided with a second communication passage 51c that communicates with the discharge port 45b, and by the suction action of the radial dynamic pressure air bearing 31c integrally provided with the axial flow generation mechanism, As shown, air is sucked in from the outside of the case through the filter 53c and the suction port 47b, and is discharged to the outside of the case through the radial dynamic pressure air bearing 31c, the second communication passage 51c, the discharge port 45b, and the filter 53c. is doing.
[0037]
In this way, the air supplied to the radial dynamic pressure air bearing is sucked from the outside of the case through the suction port, and the warmed air after cooling the radial dynamic pressure air bearing is discharged to the outside of the case through the discharge port. Since the cooling efficiency of the radial dynamic pressure air bearing or the like can be increased by discharging the same, it is possible to obtain the same effect as the third and fourth dynamic pressure air bearing type optical deflector considered by the present inventor. In addition, it can be expected to further improve the rotational speed.
[0038]
8 to 9 are a longitudinal sectional view and an enlarged view of a main part of seventh and eighth dynamic pressure air bearing type optical deflectors considered by the present inventors.
[0039]
The seventh and eighth dynamic pressure air bearing type optical deflections considered by the present inventors are mainly different from the first to sixth dynamic pressure air bearing type optical deflections considered by the present inventor. The exposed part to the outside of the case is covered with a heat insulating member as long as the function of the pump mechanism is not hindered.
[0040]
In FIG. 8, the flange portion, which is the exposed portion of the fixed shaft 21e to the outside of the case, is covered with a heat insulating member such as foamed polystyrene, and the exhaust inside the mirror chamber 19a is discharged by the pump mechanisms 41a and 43d. By not completely blocking the opening of the outlet 45a, the functions of the pump mechanisms 41a and 43d are not impaired.
[0041]
In FIG. 9, the lower portion of the case 15a is covered with a heat insulating member together with the flange portion of the fixed shaft 21e, and the opening of the discharge port 45a is completely provided so as not to hinder the functions of the pump mechanisms 41a and 43d as in FIG. It is not closed.
[0042]
In this way, by covering the exposed portion of the fixed shaft to the outside of the case with the heat insulating member as long as the function of the pump mechanism is not hindered, a temperature difference is generated throughout the bearing portion such as the pump mechanism and the radial dynamic pressure air bearing. Therefore, a predetermined clearance can be obtained from the start-up to the steady rotation, and the same effect as the first hydrodynamic air bearing type optical deflector considered by the present inventor can be obtained. be able to.
[0043]
10 to 11 are longitudinal sectional views of ninth and tenth hydrodynamic air bearing type optical deflectors considered by the present inventors.
[0044]
The ninth and tenth hydrodynamic air bearing type optical deflections considered by the present inventor are mainly different from the first to eighth dynamic pressure air bearing type optical deflections considered by the present inventor. The linear expansion coefficient of the fixed shaft or the rotating shaft is optimized so that the gap between the fixed shaft and the rotating shaft of the pump mechanism provided near the exposed fixed shaft is substantially constant before and after the motor is driven. .
[0045]
When the linear expansion coefficient of aluminum is 23 to 29E-6 / ° C., and the temperature difference between the fixed shaft and the rotating shaft is 20 ° C., the linear expansion coefficient of the rotating shaft whose thermal expansion amount varies depending on the temperature difference. Is set in the range of 15 to 18E-6 / ° C., the thermal expansion amounts of the fixed shaft and the rotating shaft become substantially equal.
Therefore, using an alloy material such as an Al—Cu—Zn alloy (aluminum bronze), Cu—Ni alloy (constantan), Fe—Cr—Ni alloy (stainless steel) having such a linear expansion coefficient, FIG. As shown in FIG. 11, by forming the alloy portions 73a and 73b integrally on the rotating shaft, the gap between the fixed shaft and the rotating shaft of the pump mechanism can be made substantially constant before and after driving the motor. Therefore, stable bearing performance can be obtained from startup to steady rotation.
[0046]
On the other hand, the same effect can be obtained by setting the linear expansion coefficient of the fixed shaft having a different amount of thermal expansion depending on the temperature difference in the range of 36 to 44E-6 / ° C.
[0047]
FIG. 12 is a longitudinal sectional view of the hydrodynamic air bearing type optical deflector according to the first embodiment of the present invention.
[0048]
The main difference between the dynamic pressure air bearing type optical deflection of the first embodiment of the present invention and the first to tenth dynamic pressure air bearing type optical deflection considered by the present inventor is that it is exposed to the outside of the case. This is because the shape near the exposed portion of the fixed shaft is optimized so that the gap between the fixed shaft and the rotating shaft of the pump mechanism provided in the vicinity of the fixed shaft is substantially constant before and after the motor is driven.
[0049]
A notch 69a is formed in the vicinity of the exposed portion of the fixed shaft 21f where the lower pump mechanism 43d is formed so that only the pump mechanism 43d remains. By forming the notch 69a, the outer periphery of the flange, which is an exposed portion of the fixed shaft 21f, and the inner periphery of the flange, where the pump mechanism 43d and the like are provided, conduct heat through a slight connection 71. Therefore, depending on the cross-sectional area of the connection portion, etc., the heat conduction characteristics are deteriorated, and the heat conduction of the temperature is deteriorated at the flange portion inner periphery and the flange portion outer periphery.
For this reason, the temperature around the lower pump mechanism 43d is almost the same as the temperature of the radial dynamic pressure air bearing 31a, and no temperature difference occurs throughout the bearings of the pump mechanism and the radial dynamic pressure air bearing. Stable bearing performance can be obtained over rotation.
[0050]
The shaft rotation type hydrodynamic air bearing type optical deflector as shown in FIG. 13 has been described so far, but the sleeve rotation type hydrodynamic air bearing type optical deflector is also shown in FIG. As described above, the gap between the fixed shaft and the rotating shaft changes due to the temperature difference. In the case of the shaft rotation type, the gap is narrowed as shown by CL3 in FIG. 13, and in the worst case, there is a risk of the seizure of the rotation shaft, but in the case of the sleeve rotation type, in FIG. As shown by CL6, there is a risk that the bearing performance is lowered due to the wide gap.
[0051]
However, the axial flow generation mechanism generates an axial flow in the radial dynamic pressure air bearing, suppresses the temperature rise of the radial dynamic pressure air bearing, or covers the exposed portion of the fixed shaft outside the case with a heat insulating member, Optimized shape near the exposed part of the fixed shaft, configured to prevent temperature differences throughout the bearings such as the pump mechanism and radial dynamic pressure air bearing, and to optimize the linear expansion coefficient of the fixed shaft or rotating shaft Therefore, it is also applicable to a sleeve rotating type hydrodynamic air bearing type optical deflector so that the gap between the fixed shaft and the rotating shaft of the pump mechanism is substantially constant before and after the motor is driven. Since it is apparent, detailed description of the sleeve rotating type hydrodynamic air bearing type optical deflector is omitted.
[0052]
Further, the gap between the fixed shaft of the pump mechanism provided in the vicinity of the flange portion of the fixed shaft exposed to the outside and the rotating shaft is made G wider than the gap between the fixed shaft and the rotating shaft of the radial dynamic pressure air bearing. Or an axial flow generating mechanism for generating an axial flow in the radial dynamic pressure air bearing is provided in the vicinity of the radial dynamic pressure air bearing or integrally with the radial dynamic pressure air bearing, and the air supplied to this axial flow generation mechanism Have been individually described, such as cooling through a discharge port that discharges to the outside of the case, or covering the exposed portion of the fixed shaft to the outside of the case with a heat insulating member as long as it does not interfere with the function of the pump mechanism. Needless to say, these may be used in appropriate combination.
[0053]
【The invention's effect】
As described above in detail, in the present invention, the following effects can be obtained.
[0054]
(1) A hollow fixed shaft erected on the case, and a rotary shaft rotatably supported by a radial dynamic pressure air bearing comprising a herringbone groove and other dynamic pressure generating portions on the outer periphery or inner periphery of the fixed shaft. A rotary polygon mirror or other rotor part that rotates integrally with the rotating shaft is housed in a case sealed by a case and a cover member, and the air in the case is moved outside the case by rotating the rotor part. In the hydrodynamic air bearing type optical deflector having a pump mechanism for reducing or evacuating the inside of the case, a fixed shaft and a rotating shaft of the pump mechanism provided in the vicinity of the fixed shaft exposed to the outside of the case So that the thickness of the fixed shaft facing the pump mechanism changes in the vicinity of the exposed portion of the fixed shaft so that the gap of the fixed shaft is substantially constant before and after driving the motor. Since a dynamic pressure air bearing type optical deflector is configured by providing a notch part with a gap that increases downward, it is possible to prevent a temperature difference from occurring throughout the bearing part. A predetermined clearance can be obtained during rotation, and a stable rotation state can be obtained without causing deterioration in bearing performance and seizure of the rotating shaft.
[0055]
[0056]
[0057]
[0058]
[0059]
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a first dynamic pressure air bearing type optical deflector considered by the present inventors.
FIG. 2 is an enlarged half sectional view of the main part of the dynamic pressure air bearing type optical deflector of FIG. 1;
FIG. 3 is an enlarged half sectional view of a main part of a second dynamic pressure air bearing type optical deflector considered by the present inventor.
FIG. 4 is a longitudinal sectional view of a third hydrodynamic air bearing type optical deflector considered by the present inventors.
FIG. 5 is a longitudinal sectional view of a fourth dynamic pressure air bearing type optical deflector considered by the inventors.
FIG. 6 is a longitudinal sectional view of a fifth embodiment of a hydrodynamic air bearing type optical deflector considered by the present inventors.
FIG. 7 is a longitudinal sectional view of a sixth hydrodynamic air bearing type optical deflector considered by the inventors.
FIG. 8 is a longitudinal sectional view of a seventh hydrodynamic air bearing type optical deflector considered by the inventors.
FIG. 9 is an enlarged cross-sectional view of a main part of an eighth hydrodynamic air bearing type optical deflector considered by the inventors.
FIG. 10 is a longitudinal sectional view of a ninth hydrodynamic air bearing type optical deflector considered by the inventors.
FIG. 11 is a longitudinal sectional view of a tenth dynamic pressure air bearing type optical deflector considered by the inventors.
FIG. 12 is a longitudinal sectional view of the hydrodynamic air bearing type optical deflector according to the first embodiment of the present invention.
13 is an enlarged half-sectional view of a main part of the A part in FIG. 23. FIG.
14 is an enlarged half-sectional view of a main part of the B part in FIG. 21. FIG.
FIG. 15 is a longitudinal sectional view showing an example of a conventional hydrodynamic air bearing type optical deflector.
16 is a half sectional view showing the periphery of the pump mechanism of the dynamic pressure air bearing type optical deflector of FIG. 15;
FIG. 17 is a longitudinal sectional view showing another configuration example of a conventional dynamic pressure air bearing type optical deflector.
18 is a half sectional view showing the periphery of the pump mechanism of the dynamic pressure air bearing type optical deflector of FIG. 17;
FIG. 19 is a longitudinal sectional view showing another configuration example of a conventional dynamic pressure air bearing type optical deflector.
20 is a plan view showing the periphery of the pump mechanism of the dynamic pressure air bearing type optical deflector of FIG. 19;
FIG. 21 is a longitudinal sectional view showing another configuration example of a conventional dynamic pressure air bearing type optical deflector.
FIG. 22 is a cross-sectional view showing another configuration example of the radial dynamic pressure air bearing.
FIG. 23 is a longitudinal sectional view showing another configuration example of a conventional hydrodynamic air bearing type optical deflector.
[Explanation of symbols]
15a, 15g, 15h, 15i: case,
17a, 17h, 17i: cover member,
19a, 19b, 19h, 19i: mirror room,
21a to 21j, 21m, 21n, 21p: fixed shaft,
23a-23e, 23g-23i, 23m, 23n, 23p-23r: rotating shaft,
31a, 31b, 31c, 31g, 31h, 31i: radial dynamic pressure air bearings,
33a, 33h, 33i, 33j: thrust bearings,
41a, 41h, 41i, 43a to 43d, 43g to 43j: pump mechanism,
45a, 45b, 45i, 45j: outlet,
47a, 47b: inlet,
49a-49c, 49f-49k, 49m, 49n, 49p: atmospheric communication passage,
51a, 51b, 51c: communication path,
53a, 53b, 53c, 53g, 53h: filter,
55a, 55b: sealing member,
57a, 57b: bottom plate,
59a, 59b: heat insulating members,
61: Rotating polygon mirror,
63: stator coil,
65: Rotor yoke,
67a, 67b: axial flow generation mechanism,
69a: notch,
71: connection part,
73a, 73b: Alloy parts.

Claims (1)

A hollow fixed shaft erected on the case, and a rotating shaft rotatably supported by a radial dynamic pressure air bearing comprising a herringbone groove or other dynamic pressure generating portion on the outer periphery or inner periphery of the fixed shaft, The rotary polygon mirror and other rotor parts that rotate integrally with the rotary shaft are accommodated in a case sealed with a case and a cover member, and the air in the case is discharged to the outside of the case by rotating the rotor part. In the hydrodynamic air bearing type optical deflector provided with a pump mechanism for reducing or evacuating the inside of the case,
As the gap between the fixed shaft and the rotating shaft of the pump mechanism provided in the vicinity of the fixed shaft which is exposed to the outside of the case is substantially constant, even before and after the driving of the motor, and the pump mechanism at the exposed portion near the fixed shaft A hydrodynamic air bearing type optical deflector characterized in that a notch portion in which a gap increases toward the lower side of the rotating shaft is provided so that the thickness of the opposed fixed shaft changes .

Images