JPS6055315A - Optical deflector - Google Patents

Abstract

PURPOSE:To constitute an optical deflector which is reducible in size and allows a spindle to rotate with high precision by bearing the thrust-directional load of the spindle by a rotor and a stator. CONSTITUTION:The spindle 6 is provided in a housing 1 while inserted into dynamic pressure air journal bearings 3 and 4. Further, a polygon mirror 10 in a plane regular polygonal shape is provided in the housing 1 coaxially with the spindle 6. The spindle 6 and polygon mirror 10 are made of aluminum in one body. Rotors 31 made of plane annular permanent magnets are provided to both end surfaces of the polygon mirror 10, and stators 32 made of permanent magnets in the same shape with the rotors 31 are provided on the surfaces facing the rotors so that the stators repulse the rotors 31. Consequently, the rotors 31 and stators 32 bear the thrust-directional load of the spindle 6, and the interaxis distance between the dynamic pressure air journal bearing 3 and 4 is reduced greatly. Consequently, the rotating performance of the spindle 6 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical deflector in which a polyhedral mirror mechanically rotates to deflect light.

[Technical background of the invention and its problems]

Recently, laser printers using semiconductor lasers have been developed. In this laser printer, an optical deflector using a polyhedral mirror is used to convert information such as a document into an electrical signal. This polyhedral mirror generally has the shape of a thin regular polygon, and has mirror-finished reflective surfaces on its side surfaces. The polyhedral mirror is installed coaxially with a rotatable spindle, and is rotated by the spindle to reflect incident light in different directions. At this time, in order to obtain high resolution in the above electrical signal conversion,
Set the spindle rotation speed to high speed (10'rpm or more),
It is necessary to increase the speed of light deflection. Furthermore, since an optical system is used as the conversion means, it is necessary to maintain the positional accuracy of the polygonal mirror at a very high level of accuracy, and for this purpose, the rotational accuracy of the spindle must be made tooth-accurate. In other words, the spindle is required to rotate at high speed and with high rotation accuracy. For this reason, a herringbone type or tilting pad type dynamic pressure gas journal bearing and a repulsion type magnetic thrust bearing are used as spindle bearings. By using these two bearings together, the above conditions are satisfied, and other advantages such as low frictional torque loss and no need for lubricating oil can be obtained.

Conventionally, when using the above-mentioned hydrodynamic gas journal bearing and magnetic thrust bearing, a motor for rotating the spindle between the hydrodynamic gas journal bearings provided at both ends of the spindle.

Many are equipped with polyhedral mirrors. It's a moat, some have a polyhedral sharp point at one end of the spindle. Note that the magnetic thrust bearing that supports the force in the thrust direction of the spindle is generally provided at the end of the spindle along with one of the hydrodynamic gas journal bearings. As described above, conventionally, a hydrodynamic gas journal bearing, a magnetic thrust bearing, a polyhedral mirror, a motor, etc. are arranged in series with the spindle. For this reason, the length of the spindle itself becomes long, resulting in a disadvantage that the entire optical deflector becomes large. In order for the spindle to rotate with high precision, it is advantageous for the span between the hydrodynamic gas journal bearings to be small. However, as mentioned above, when the spindle becomes longer, the span between the bearings also becomes longer, which is disadvantageous in terms of rotational accuracy.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical deflector that can be miniaturized and whose spindle can be rotated with high precision.

[Summary of the invention]

The present invention is an optical deflector that reflects incident light by a polyhedral sharp provided on a rotatable spindle, and that rotates the polyhedral sharp by the spindle to orient the reflected light in different directions. A light comprising a rotor made of permanent magnets provided on both end faces of the rotor, and a stator made of permanent magnets provided at a position facing the rotor and facing the rotor with the same polarity. This is a deflector, and the load in the thrust direction of the spindle is supported by the above-mentioned rotor and solid foot.

[Embodiments of the invention]

An embodiment of the invention will be described with reference to the drawings. FIG. 1 is a sectional front view showing this embodiment. Cylindrical housing (
A bearing mounting base (2) forming a disk-shaped lid is attached to the upper part of the bearing 1). Cylindrical dynamic pressure gas journal bearings (3) and (4) are provided at the bottom of the housing (1) and at the center of each of the bearing mounts (2). Further, a light source incident light (5) through which light from a light source enters is opened at the side of the housing (1). Furthermore, the housing (1
) is provided with a spindle (6) inserted into hydrodynamic gas journal bearings (3) and (4). Further, inside the housing (1), a flat regular polygonal polyhedral mirror (10) is provided coaxially with the spindle (6). In this embodiment, the spindle (6) and the polyhedral mirror 0@ are made of aluminum and are integrally constructed. Polyhedral mirror (10
) is a mirror-finished reflective surface (Lυ,...). This reflective surface (11) is processed to be parallel to the rotation axis of the spindle (6). ,
At the center of both ends of the polyhedral mirror α0), large diameter portions (12) having the same outer diameter as the hydrodynamic gas journal bearings f3) and (4) are provided. The sliding shaft portions (16) and (ty) have semicircular cross-sectional grooves α9 carved in the direction of the rotation axis at equal intervals at locations facing the bearings (3) and (4). The bearing clearance between the shaft part CL (9, (17+) and the dynamic pressure gas journal bearing (1, 51, (1) is several μm to several 1
It is formed to have a thickness of 0 μm. Furthermore, a motor holder is provided at the bottom of the housing (1) to rotate the spindle (6). At the lower end of this motor (inside the hot water, that is, the sliding shaft portion 05), the spindle (6) has a small diameter portion (21) with a small diameter. This small diameter part (
2υ is a motor (2()) that rotates the spindle (6).
It is attached by motor rotation -1 (2z is screw smooth). Further, this motor rotor (with a cylindrical motor stator C24 around the rotor) is supported and fixed by a support member C74 attached to the bottom of the housing (1).

On the other hand, rotors (31) made of flat donut-shaped permanent magnets are provided at both ends of the polyhedral mirror 00).

The inner diameter of this rotor 61) is slightly larger than the diameter of the large diameter portion (12), and the rotor 01) is inserted into the large diameter portion (12). Furthermore, a rotor 61) is attached to both ends of the polyhedron sharp 00).
A structure with the same shape as the rotor is provided, and the rotor (3+i is fitted into this clearing).

The large diameter portion (12) and the rotor 01) are mounted so as to be flush with each other. In addition, the position facing this rotor 01), that is, the bottom of the housing (1) and the bearing mounting base (2
) is provided with an identifier I3 made of a permanent magnet having the same shape as the rotor Gl). This stator is 0, the rotor is 0.
It is installed so that it faces the same polarity as 1).

Therefore, the rotor 01) and the stator G2 repel each other. In addition, like the rotor (31), the stator 0 is inserted into the hydrodynamic gas journal bearings (3) and (4), respectively, and is attached to the bottom of the housing (1) and the bearing mounting base (2).
) into the groove carved in the Therefore, the stator (32
The bearings are also mounted so that their surfaces are flush with the hydrodynamic gas journal bearings (3) and (4).

Next, the operation of this embodiment having the above-described configuration will be explained. The spindle (6) has a rotor (31) and a stator 02
Because they repel each other, they float in the axial direction. At this time, the bottom of the housing (1) and the polyhedron 11 + to
) The rotor (31) and stator (
1 of the other rotor so that the repulsion force is greater towards the
).

A stator with a higher magnetic flux density than the three stators c is used. In this way, since the spindle (6) is floating,
When the spindle (6) is rotated by one layer of motor,
The initial starting torque at this time becomes very small. Furthermore, due to the hydrodynamic gas journal bearings (3), (4), rotor (3]1, and stator C32, the rotation of the spindle (6) becomes extremely smooth during rotation of the spindle (6). , achieving rotation with even more surface precision.

Here, when the laser light enters from the light source entrance port (5),
It hits the reflecting surface (11) of the polyhedral mirror (10), but since the spindle (6) and the multi-faceted mirror (10) are rotating at high speed, the reflecting mirror (1υ) does not move at high speed between the circumferential directions. The laser beam is reflected.Then, the reflected laser beam scans a predetermined location.

As described above, in this embodiment, a polyhedral screw (rotor 61 made of flat donut-shaped water magnets on both end faces of +ul) is provided, and a rotor C is provided on the face facing rotor C3+1.
i61 constantor (32), which has the same shape as 31) and is made of permanent stone.
Since the rotor 61) and the stator G4 support the load in the thrust direction of the spindle (6), the hydrodynamic gas journal bearing (3) supports the load in the thrust direction of the spindle (6). , (4), the distance between the axes can be made very small. Therefore, it is possible to improve the rotational performance of the spindle (6), and it is also possible to downsize the entire device.

In this embodiment, so-called full-circle type hydrodynamic gas journal bearings (3) and (4) were used as the gas bearings, but this is not the only option; for example, herringbone type or tailing band type bearings may be used. . Furthermore, the rotor 01) and the stator 621 do not necessarily have the same shape.

〔Effect of the invention〕

As explained above, the optical deflector of the present invention is compact overall, and furthermore, the spindle can be rotated at a high frequency. For this reason, for example, in a laser printer, the entire device can be made smaller, and it can also be a high-performance device, which has a very large effect.

[Brief explanation of drawings]

The drawing is a sectional front view showing one embodiment of the present invention. (6)...spindle, (10)...polyhedral mirror. t31)...Rotor, 04...Stator.

Claims (1)

[Claims] An optical deflector that reflects incident light by a polygonal mirror provided on a rotatable spindle, and deflects the reflected light in different directions by rotating the polygonal mirror with the spindle, provided on both end surfaces of the polygonal mirror. An optical deflector comprising: a rotor made of a permanent magnet, and a stator made of a permanent magnet, which is provided at a position facing the rotor and faces the rotor with the same polarity.