JP4105813B2 - Dynamic pressure air bearing type optical deflector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a hydrodynamic air bearing type optical deflector used for a laser printer or the like, and in particular, a small and highly precise dynamic pressure used for a device requiring high precision and high speed rotation such as a color laser printer. The present invention relates to an air bearing type optical deflector.
[0002]
[Prior art]
A conventional hydrodynamic air bearing type optical deflector will be described with reference to FIGS.
[0003]
FIG. 8 is a longitudinal sectional view of a conventional sleeve rotation type dynamic pressure air bearing type optical deflector. A fixed shaft 63 in which a dynamic pressure groove (not shown) is engraved is press-fitted substantially in the center of the case 61. A hollow sleeve 69 is rotatably supported on the outer periphery of the fixed shaft 63 by a radial dynamic pressure bearing generated by the dynamic pressure groove. A flange portion for mounting the mirror 71 is formed on the sleeve 69. The mirror 71 is fixed to the flange portion by a method such as screwing, and a rotor magnet is fixed below the flange portion. ing. A stator coil is fixed to the case 61 at a position facing the rotor magnet. By appropriately energizing the stator coil, the rotor portion such as the sleeve 69, the mirror 71, the rotor magnet, etc. Rotate at high speed.
[0004]
On the other hand, FIG. 9 is a longitudinal sectional view of a conventional axial rotation type hydrodynamic air bearing type optical deflector. A hollow sleeve 33 is inserted from below into a substantially central portion of the case 35 and fixed through a bottom plate 41. It is fixed by a screw 43. A cylindrical rotating shaft 31 is disposed on the inner periphery of the sleeve 33, and the rotating shaft 31 is rotatable by a dynamic pressure groove (not shown) formed on the inner periphery of the sleeve 33 or the outer periphery of the rotating shaft 31. It is supported by. A hub 45 having a mirror mounting surface is fixed to the rotary shaft 31, and a mirror 51, a rotor magnet, etc., together with the rotary shaft 31, a sleeve 33, similar to the sleeve rotating type hydrodynamic air bearing type optical deflector. Rotates the inner circumference of the high speed.
[0005]
Here, in the sleeve rotation type dynamic pressure air bearing type optical deflector, since the rotational moment is large, the sleeve 69 is likely to be deformed. When the sleeve 69 is deformed, the rigidity of the dynamic pressure air bearing is lowered. Therefore, when a mirror to be mounted is large, a shaft rotation type hydrodynamic air bearing type optical deflector as shown in FIG. 9 is advantageous.
[0006]
[Problems to be solved by the invention]
However, in such a conventional shaft rotation type hydrodynamic air bearing type optical deflector, as the demand for high precision, high speed rotation, and downsizing increases, it is in the direction of downsizing and weight reduction including the bearing part, It is necessary to keep the wall thickness to the minimum with respect to the inner diameter of the sleeve. As a result, when the sleeve is fixed to the case with a screw, the stress acts on the sleeve, so that the sleeve is slightly deformed. Was confirmed by experiments.
[0007]
Further, it was confirmed by experiments that a stress due to a difference in linear expansion coefficient was generated between the case and the sleeve due to a change in environmental temperature, and the sleeve was slightly deformed by this stress.
[0008]
The slight deformation of this sleeve is a level that does not cause a problem in the specification that does not particularly require accuracy, so it seems that it has been overlooked so far, but it tries to achieve high speed rotation such as 50,000 rotations again. In this case, these problems were recognized for the first time, and it was further confirmed by experiments that this slight deformation of the sleeve would cause deterioration of surface accuracy (jitter, etc.) and noise.
[0009]
The present invention has been made in order to eliminate these drawbacks in view of the above-described conventional drawbacks. In response to the growing demand for miniaturization, the present invention aims to reduce the size and weight of bearings. Another object of the present invention is to obtain a hydrodynamic air bearing type optical deflector that suppresses the deformation of the sleeve to a minimum amount, has high surface accuracy and is low in noise.
[0010]
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.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a case, a hollow sleeve fixed to the case, a rotation shaft rotatably supported on the inner periphery of the sleeve, and a rotation shaft integrally rotating with the rotation shaft. In the hydrodynamic air bearing type optical deflector that rotationally drives the rotor part by appropriately energizing a stator part provided on the outer periphery of the sleeve, the sleeve and the case face each other. Three or more convex portions are formed on one or both of them, and a dynamic pressure air bearing type optical deflector is configured by fixing a sleeve to the case with screws through the three convex portions.
[0012]
A sleeve, a hollow sleeve fixed to the case, a rotating shaft rotatably supported on the inner periphery of the sleeve, and a rotor portion that rotates integrally with the rotating shaft; In a hydrodynamic air bearing type optical deflector that rotationally drives the rotor portion by appropriately energizing the stator portion provided on the outer periphery, the sleeve is fixed to the case with screws through three space members having a substantially uniform thickness. By doing so, a dynamic pressure air bearing type optical deflector is configured.
[0013]
Furthermore, the dynamic pressure air bearing type optical deflector is configured by forming the case and the sleeve by members having substantially the same linear expansion coefficient.
[0014]
Embodiment
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0015]
FIG. 1 is a longitudinal sectional view of a hydrodynamic air bearing type optical deflector according to a first embodiment of the present invention, and FIG. 2 is a bottom view of the hydrodynamic air bearing type optical deflector.
[0016]
Reference numeral 5 denotes a case, which has a hole portion into which a sleeve 33 (described later) is inserted in a substantially central lower portion, and a stator coil for rotating the rotor portion and a rotor portion in the thrust direction are supported on the side wall thereof. And a circuit board on which a detection element such as a Hall element is mounted is fixed. And in the location which fixes the below-mentioned sleeve 33 with the fixing screw 43, three convex parts 5a are formed on the same circumference at intervals of about 120 degrees.
[0017]
Reference numeral 33 denotes a hollow sleeve having a flange portion at the lower portion. The flange portion is inserted into a hole provided at a substantially lower center portion of the case 5 so that the upper surface of the flange portion is in contact with the convex portion 5a of the case 5, With the bottom plate 41 covered with a bottom plate 41 having an air circulation hole, it is fastened and fixed to the case 5 together with the bottom plate 41 by a fixing screw 43.
[0018]
A hub 45 having a mirror mounting surface is fixed to the outer periphery of the upper end of the rotation shaft 31 and is inserted into the inner periphery of the sleeve 33 from the upper portion of the sleeve 33. A mirror 51 is mounted on the mirror mounting surface of the hub 45 and is pressed and fixed by a mirror locking member 53. Further, a rotor yoke and a rotor magnet are fixed to a portion of the outer periphery of the lower end portion of the hub 45 facing the stator coil.
[0019]
The dynamic pressure air bearings formed on the inner peripheral surface of the sleeve 33 and the outer peripheral surface of the rotary shaft 31 support the rotor portion such as the sleeve 33 that is a fixed shaft, the rotary shaft 31, the hub 45, and the like. By appropriately energizing the stator coil, the rotor portion can be rotated at high speed.
[0020]
By the way, when the sleeve 33 is fastened and fixed to the case 5 with a fixing screw, in the conventional hydrodynamic air bearing type optical deflector 93 (see FIG. 9), the entire upper surface of the flange portion of the sleeve 33 contacts the bottom surface of the case 35. As shown in FIGS. 6 (A) and 6 (B), the sleeve 33 is slightly deformed due to being fixed with the fixing screw 43 in the contact state. confirmed. (A) and (B) schematically represent the sleeve cross-sectional shapes at locations corresponding to the central portion and the lower portion of FIG. Note that the alternate long and short dash line in the figure schematically represents the cross-sectional shape of the sleeve in an ideal state.
[0021]
This is a level that does not cause any problems when used at about 20,000 revolutions, and until now there was no recognition, but high accuracy, high speed rotation, and miniaturization. As demand increases, it is in the direction of miniaturization and weight reduction including the bearing part, and it is necessary to minimize the wall thickness with respect to the inner diameter of the sleeve. It has been confirmed by experiments that the slight deformation of the sleeve causes deterioration of surface accuracy (jitter and the like) and noise.
[0022]
On the other hand, in the dynamic pressure air bearing type optical deflector according to the first embodiment of the present invention, only the three convex portions 5a formed on the case 5 abut on the upper surface of the flange portion of the sleeve 33. In this state, since it is fastened and fixed by the fixing screw 43, as shown in FIG. 5C (corresponding to the central portion of FIG. 6), the sleeve 33 hardly deforms and prevents an increase in noise level. It is possible to prevent deterioration of surface accuracy (such as jitter).
[0023]
It should be noted that the bottom plate 41 can be made unnecessary and, of course, a portion not directly related to the present invention, such as a thrust magnetic bearing and a mirror mounting method, may be arbitrarily configured. , Herringbone, wedge, multi-arc, etc.
[0024]
Next, another embodiment of the present invention will be described with reference to FIGS. In addition, about the structure same as the dynamic pressure air bearing type | mold optical deflector of the 1st Embodiment of this invention, the description is abbreviate | omitted by providing the same code | symbol.
[0025]
FIG. 3 is a longitudinal sectional view of the hydrodynamic air bearing type optical deflection according to the second embodiment of the present invention. The difference from the first embodiment of the present invention is that the three protrusions 3a are formed by the sleeve 3. This has the same effect as that of the first embodiment.
Further, the same effect can be obtained by forming the three convex portions at locations where both the case and the sleeve abut.
[0026]
FIG. 4 is a longitudinal sectional view of a hydrodynamic air bearing type optical deflection according to a third embodiment of the present invention. The difference from the first and second embodiments of the present invention is that the case or sleeve is Instead of providing three protrusions, the space member 7 having a substantially uniform thickness is inserted, which has substantially the same effect as the first and second embodiments, and that existing parts can be used as they are. Has an effect.
[0027]
Although illustration is omitted, the hydrodynamic air bearing type optical deflection of the fourth embodiment of the present invention is different from the first and second embodiments of the present invention in that the case and the sleeve are linearly expanded. The reason is that they are formed by members having substantially the same coefficient.
[0028]
Here, FIG. 7 is a diagram showing the correlation between the rotational speed and the noise level. The broken line in the figure is a conventional hydrodynamic air bearing type optical deflector, and the solid line is the fourth embodiment of the present invention. 1 shows a hydrodynamic air bearing type optical deflector.
As is apparent from this figure, in the hydrodynamic air bearing type optical deflector of the fourth embodiment, the noise level is slightly increased even in the ultrahigh speed rotation region of 40,000 rotations or more. It is not recognized, and it can be seen that a stable rotating state is maintained.
This is because the linear expansion coefficient of the case and the sleeve is almost the same even if the case or sleeve expands or contracts due to use in the ultra-high speed rotation region or changes in environmental temperature. Since the initial state can be maintained, deformation of the sleeve can be suppressed as much as possible, and an increase in noise level can be prevented. In particular, since the case and the sleeve are fixed by contacting only the three convex portions, the deformation of the initial sleeve can be suppressed to the minimum, so that it is stable from the low-speed rotation region to the ultra-high-speed rotation region. Can be obtained.
[0029]
Thus, in the dynamic pressure air bearing type optical deflector according to the fourth embodiment of the present invention,
In addition to minimizing the deformation of the sleeve at the time of initial fixing between the case and the sleeve, the fixed state between the case and the sleeve does not change even when the environmental temperature changes, and a stable rotational state can be obtained. The increase in noise level can be prevented.
[0030]
In addition, a member having substantially the same linear expansion coefficient means a member made of almost the same material, such as an aluminum material for an aluminum alloy material, and a member made of the same member, such as an aluminum alloy material for an aluminum alloy material. Including.
[0031]
【The invention's effect】
As described above in detail, in the present invention, the following effects can be obtained.
[0032]
(1) A sleeve comprising: a case; a hollow sleeve fixed to the case; a rotary shaft rotatably supported on the inner periphery of the sleeve; and a rotor portion that rotates integrally with the rotary shaft, In the hydrodynamic air bearing type optical deflector that rotationally drives the rotor portion by appropriately energizing the stator portion provided on the outer periphery of the sleeve, there are three protrusions on one or both of the surfaces facing the sleeve and the case. Formed in the dynamic pressure air bearing type optical deflector by fixing the sleeve to the case with the screws through the three convex portions, so that the sleeve is generated when the sleeve is fixed to the case. Therefore, the increase in the noise level can be prevented, and the deterioration of the surface accuracy (such as jitter) can be prevented.
[0033]
(2) a sleeve, a hollow sleeve fixed to the case, a rotating shaft rotatably supported on the inner periphery of the sleeve, and a rotor portion that rotates integrally with the rotating shaft; In the hydrodynamic air bearing type optical deflector that rotationally drives the rotor portion by appropriately energizing the stator portion provided on the outer periphery of the sleeve, the sleeve is screwed into the case via three space members having a substantially uniform thickness. Since the dynamic pressure air bearing type optical deflector is configured by fixing, it has substantially the same effect as the above (1) and also has the effect that the existing parts can be used as they are.
[0034]
(3) In addition to the above (1) and (2), since the case and the sleeve are formed of members having substantially the same linear expansion coefficient, a dynamic pressure air bearing type optical deflector is configured. While having the same effect as the above (1) and (2), the fixed state between the case and the sleeve does not change even when the environmental temperature changes, and a stable rotational state can be obtained and the noise level can be obtained. It is possible to prevent an increase in the amount.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a hydrodynamic air bearing type optical deflector according to a first embodiment of the present invention.
FIG. 2 is a bottom view of the hydrodynamic air bearing type optical deflector according to the first embodiment of the present invention.
FIG. 3 is a longitudinal sectional view of a hydrodynamic air bearing type optical deflector according to a second embodiment of the present invention.
FIG. 4 is a longitudinal sectional view of a hydrodynamic air bearing type optical deflector according to a third embodiment of the present invention.
FIG. 5 is a longitudinal sectional view showing a structure of a sleeve.
FIG. 6 is a schematic diagram showing a deformed state of a sleeve.
FIG. 7 is a diagram showing a correlation between the rotation speed and the noise level.
FIG. 8 is a longitudinal sectional view of a conventional hydrodynamic air bearing type optical deflector.
FIG. 9 is a longitudinal sectional view of another conventional hydrodynamic air bearing type optical deflector.
[Explanation of symbols]
1a, 1b, 1c, 91, 93: dynamic pressure air bearing type optical deflector,
5, 35, 61: Case, 3, 33, 69: Sleeve,
3a, 5a: convex part, 7: space member,
31: Rotating shaft, 63: Fixed shaft,
45: Hub, 51, 71: Mirror,
53: Mirror locking member, 41: Bottom plate,
43: fixing screw, 65: cover.

Claims (3)

A case, a hollow sleeve fixed to the case, a rotating shaft rotatably supported on the inner periphery of the sleeve, and a rotor portion that rotates integrally with the rotating shaft; In the dynamic pressure air bearing type optical deflector for rotating the rotor part by energizing the provided stator part as appropriate,
A hydrodynamic air bearing type characterized in that three convex portions are formed on one or both of the surfaces where the sleeve and the case face each other, and the sleeve is fixed to the case with screws through the three convex portions. Optical deflector. A case, a hollow sleeve fixed to the case, a rotating shaft rotatably supported on the inner periphery of the sleeve, and a rotor portion that rotates integrally with the rotating shaft; In the dynamic pressure air bearing type optical deflector for rotating the rotor part by energizing the provided stator part as appropriate,
A hydrodynamic air bearing type optical deflector characterized in that a sleeve is fixed to a case with screws through three space members having a substantially uniform thickness. 3. The hydrodynamic air bearing type optical deflector according to claim 1, wherein the case and the sleeve are formed of members having substantially the same linear expansion coefficient.

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