JPS63257716A - Polygon mirror - Google Patents

Abstract

PURPOSE:To make the assembly and arrangement durable, and to facilitate the balance adjustment by inserting and holding a rotor by a thrust receiving member from both its sides, and providing a groove for generating dynamic pressure, on the sliding surface opposed to the receiving member of this rotor. CONSTITUTION:In the outside periphery of a fixed axis 5 provided on a supporting body 4 by passing through a through-hole 1 of a plate-like rotor 3 having plural specular surfaces 2, in which the through-hole 1 is formed in the center, and whose outside peripheral edges are a regular polygon, a polygon rotor is provided so as to be freely rotatable on a bush 51 which forms a dynamic pressure generating groove 111 on the outside peripheral surface, a stator coil 6 which is separated in the axial direction from the plate-like rotor 3 and fixed to the supporting body 4, and rotates the polygon rotor is provided on the supporting body 4 or a cover body 12, and by a permanent magnet provided on the rotor 3 or a magnet of a secondary conductor, and the stator coil 6, the rotor 3 is rotated. A motor unit is constituted, the dynamic pressure generating groove 11, namely, a spiral groove is formed on both sides of the rotor 3, a thrust receiving member 10 is interposed and arranged so as to be opposed to sad groove and pressed, and inserted and held by both ends of the bush 51, and a thrust dynamic pressure bearing is formed.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a laser scanning optical system used in laser printers, barcode readers, laser copying machines, etc., in which laser light is reflected and irradiated onto the surface of a photoreceptor. This relates to a polygon mirror for

[Conventional technology]

As shown in Figure 7, a conventional polygon mirror is a known example of a sealed structure suitable for high-definition image processing.In a laser printer, a polygon mirror is rotated by laser light from a laser unit consisting of a semiconductor laser, gas laser, etc. The light is reflected by a mirror b of the rotor a and irradiated onto the surface of the photoreceptor, and the polygon rotor a is configured to be rotated by a drive motor C on a fixed shaft d via a sleeve e.

A large number of grooves for generating dynamic pressure are formed on the outer peripheral surface of the fixed shaft d, so that dynamic pressure for supporting thrust loads and radial loads is generated by rotation of the rotating sleeve e. That is, this groove for generating dynamic pressure is functionally configured to generate dynamic pressure by the lower groove f having a herringbone shape, the middle groove ``2'' forming the herringbone shape, and the upper groove f3 to apply a radial load. Air is sent to the upper surface of the fixed shaft d through the support and central groove f2, thereby increasing the air pressure between the fixed shaft d and the thrust bearing g at the upper end to support the thrust load.

A polygon rotor a is screwed to the upper part of the rotating sleeve e, and a rotor magnet C1 is fixed to the lower part.
A stator coil C2 for driving the rotor magnet c is fixed so as to surround the rotor magnet c1 to form a drive morph C, and a laser beam is irradiated from the outside onto the mirror b of the polygon rotor a. and a polygon rotor which is formed on a part of the upper circumferential surface of the outer tube i, and is rotated at high speed by a drive motor C. Not only is it necessary to maintain high rotational accuracy, but also the surface runout of the reflecting surface must be reduced, so the gap between the fixed shaft and the rotating sleeve is extremely narrow.

[Problem that the invention seeks to solve]

However, since such laser printers reproduce clear characters and images at high speed, the polygon mirror must be rotated at high speed and with minimal tilting of the reflective surface. It is manufactured by diamond-cutting a flat plate of aluminum alloy, which is easy to cut and has a high reflectivity, but in order to maintain its shape, it was over 10 fins thick. However, when a polygon mirror rotates at high speed, most of the load is due to air resistance at the outer edge of the polygon, and the area that reflects the laser beam is
Considering that the polygon mirror is narrow enough to be smaller than a crane, the power loss caused by the disturbance of the surrounding air by the polygon mirror becomes extremely large.

For these reasons, the sliding part between the fixed shaft and the rotating sleeve is machined with extreme precision to effectively generate dynamic pressure from the air, and the rotating sleeve, polygon rotor,
Rotating parts such as the mirror and rotor magnets must be precisely machined, and at the same time the mass balance must be suitably adjusted.

However, the inclination of the reflective surface of the polygon mirror is ±1.
In order to achieve a diameter of 5 μm or less, the fixed shaft with a length of 50 f1 or more must be precisely machined and the distance between it and the rotating sleeve must be 3 μm or less, which makes mass production difficult, and requires even higher speed image processing. When performing this, it is desirable to increase the rotation speed of the polygon mirror to 30,000 rpm or more, but in the case of such high-speed rotation, the radial load on the fixed shaft increases, and support by an air film is extremely difficult. There were many problems such as difficulty.

The present invention aims to accurately eliminate these conventional drawbacks by creating a compact polygon mirror that significantly improves the perpendicularity and parallelism of the polygon rotor, has less air resistance during rotation, and is capable of high-speed rotation. In addition, the reflective surface is less likely to fall (it is safe for safety because it can receive thrust loads in both forward and reverse rotations, and is also capable of stable high-speed rotation, making it a polygon mirror that can accurately reflect laser beams, etc.) The purpose is to provide it in a simple, easy-to-manufacture, and inexpensive form.

[Means for solving problems]

The present invention provides a polygon mirror in which a rotating body with a mirror surface is rotatably provided on a fixed shaft provided on a support body to form a polygon rotor, a magnet is provided on the rotating body, and a stator coil is provided corresponding to the magnet. , a bushing is fitted and arranged on the fixed shaft, the rotating body is rotatably fitted to the bushing, and a groove for generating dynamic pressure is provided on either the outer peripheral surface of the bushing or the sliding surface on the rotating body side facing the bushing. The rotating body is held between thrust receiving members on both sides thereof, and the fixing member is fitted together with the bushing onto the fixed shaft, and the rotating body and the receiving member are moved to either side of the opposing sliding surfaces. This is a polygon mirror characterized by being provided with pressure generating grooves.

〔Example〕

Embodiments of the present invention will be described with reference to FIGS. 1 and 2. In the example shown in FIG. 1, a plate-shaped rotating body is formed with a through hole 1 in the center and has a plurality of mirror surfaces 2 whose outer periphery is a regular polygon. 3 is rotatably provided on the bush 5°, which is located on the outer periphery of the fixed shaft 5 provided on the support body 4 through the through hole 1, and has a dynamic pressure generating p 11 + formed on the outer periphery surface. A stator coil 6 is provided on the support body 4 or the cover integral 12, and is fixed to the support body 4 at a distance from the flat rotary body 3 in the axial direction, and rotates the polygon rotor. The magnet 7, which is a permanent magnet or a secondary conductor, and the stator coil 6 constitute a moke unit that rotates the rotating body 3, and generates dynamic pressure on both sides of the rotating body 3. g1! That is, a spiral groove is formed, and a receiving member 10 serving as a thrust receiving plate is interposed and disposed opposite to the spiral groove, and is pressed and clamped to both ends of the bushing 5° to form a thrust dynamic pressure bearing.

The rotating body 3 has a sliding surface with dynamic pressure generating grooves 11 facing the receiving member 1'O, and has dynamic pressure generating grooves 11 on both surfaces of the sliding surface of the opposing surface. For example, a hard ceramic material in which spiral grooves with opposite twisting directions are formed leaving a land portion, such as a SiC sintered body, an α-5iC sintered body containing BeO, or a 5iJa sintered body, is used. The bearing member 10 may also be formed as a thrust bearing plate by using a flat plate made of a hard ceramic material. The clearance between the rotating body 3 and the receiving member 10 of the thrust receiving plate is 5 to 15
When the rotating body 3 is started, it comes into close contact with the lower support member 10 side, dynamic pressure is generated after rotation, and after floating, it can operate close to the upper support member 10 side.

The magnet 7 is embedded in the insertion hole 8 of the rotating body 3.
Then, the upper surfaces may be flatly aligned, or the magnet 7 may be placed in a recessed or protruding state from the upper surface of the insertion hole 8, and a back amplifier plate (not shown) may be applied to hold it. Good too. In the example shown in FIG. 1, the magnets 7.7 are held on both sides of the rotating body 3 in order to increase the power.

A plurality of insertion holes 8 are formed and arranged in a ring shape in the rotating body 3, and are arranged in a ring shape so as to form a disc-shaped rotor core, and are arranged in a ring shape along a plane perpendicular to the fixed shaft 5. It is also possible to have a plurality of magnetic poles magnetized, and furthermore, the mirror surface 2 can be made of aluminum foil (0.1 to 0.0.
It is convenient to form part of the mirror with a coating layer with high reflectance, such as a vapor-deposited film or other coating layer with high reflectivity.

In the figure, reference numeral 111 denotes a herringbone-shaped dynamic pressure generating groove, which is provided in large numbers on either the outer peripheral surface of the bushing 51 fitted to the fixed shaft 5 or the corresponding side surface of the rotating body to form a radial bearing. are doing.

Reference numeral 12 is an integrated cover, which is fitted onto the support 4 to provide a sealed structure for laser printers, etc., and can be omitted when high clarity is not required, such as for bar code leagues. Reference numeral 13 is a light projection window, and reference numeral 14 is a fastening pad to prevent loosening due to temperature expansion over time.

Note that when the spiral direction of the dynamic pressure generation groove 11 is provided on both sides, it will not burn out even if it is provided in the opposite direction (same direction on the projection plane) and accidentally rotated in the opposite direction when rotating the polygon rotor. In other words, the dynamic pressure effect is generated during both forward and reverse rotation, and the thrust load is received to be effective for safety reasons. One of them may be provided with a clutch action. In this case, it is considered that an intermediate member is interposed and utilized, and furthermore, the mirror surface 2 on the outer periphery of the rotating body 3 can also be balanced with aluminum foil.

In this specific example, a sleeve-shaped bushing 51 made of a ceramic material having a herringbone-shaped groove on the outer periphery is provided on the metal fixed shaft 5 as the fixed shaft 5, but as a means for restraining the flying height of the rotating body 3. The upper receiving member 10 provided on the fixed shaft 5 at a position above the rotary body 3 is fixed to the washer 15 and the fixing naso 16, and other stoppers are selected, but the receiving member 10 is fixed with a coil spring 17 or A configuration may also be adopted in which a spring washer or other elastic member is attached, or another elastic structure is provided on the fixed shaft 5 above the rotating body 3 as a pressing member.

Further, the support body 4 is made of an aluminum material and is used to prevent the sliding member from rotating, but the fixed shaft 5 and the support body 4 are also made of a ceramic material mainly composed of SiC. Furthermore, the support body 4 is made of a magnetic material so that an attractive force is always exerted between it and the magnet 7 to prevent the rotating body 3 from falling, and this attractive force allows for stable rotation. You may consider obtaining it. Furthermore, the fixed shaft 5 is a sleeve-shaped bushing 5. which is precisely machined to ensure parallelism between the shaft end surfaces and perpendicularity to the herringbone groove surface. 5. Fit and deploy the bushings. may be used as a stepped shaft to correspond to each member. In addition, a flat stator coil 6 is provided on the support body 4 and the cover unit 12, respectively, in response to the magnet 7 provided on the rotating body 3, and serves as a motor to rotate the rotating body 3 of the polygon rotor.

Therefore, the rotating body 3 with the mirror surface 2 is smoothly rotated with good mass balance, fluid balance, and magnetic balance on the sleeve-shaped bushing 51 of the fixed shaft 5 on the support 4, and the air resistance during rotation is It is also small and easy to drive.

In this case, a dynamic pressure generating groove 11 is provided on the corresponding surface of the receiving member 10 interposed between the supporting body 4 and the rotary body 3, and the opposite side thereof is a smooth flat surface that serves as a thrust bearing portion. In addition, the radial bearing part has a herringbone-shaped dynamic pressure generating groove 111 formed on either the outer circumferential surface of the sleeve-shaped bushing 5I on the fixed shaft 5 or the cylindrical surface of the through hole l, and In this embodiment, a11 for generating dynamic pressure to support the thrust load and fR11+ for generating the dynamic pressure to support the radial load each have a diameter of about 3 to 50 μm. This is the groove depth. The dynamic pressure generating grooves 11 may be formed on both sides of the rotating body 3 to improve balance and eliminate deformation.

The rotating body 3 and/or the receiving member 10 have zero waviness over the entire surface.
．． After making the land surface a smooth plane with a surface roughness of 3 μm or less and a maximum surface roughness of 0.1 μm, it was
It is preferable to use a material with a spiral groove machined to a depth of ~50 μm.

Note that when manufacturing a radial bearing that utilizes the hydrodynamic effect, the above-mentioned shot blasting can be used to form grooves. In any case, is the bearing part used to generate the dynamic pressure with high precision? It is possible to process fl 11 and iL, and the shape of the sliding part suitable for generating dynamic pressure is maintained even when dynamic pressure is generated, and moreover, it is resistant to solid sliding that occurs when starting and stopping. However, if the load is to a certain extent, it is durable and can be used effectively.

In the example shown in FIG. 2, the bush 5I is held between the receiving members 10 and 10 by a fixing nut 16 provided on the fixed shaft 5 and a coil spring 17, and the stator coil 6 is attached to the cover 1.
It is provided in 2. Note that the support member 4 may also serve as the receiving member 10 between the rotating body 3 and the support member 4, and in this case, the support member 4 may be formed of a ceramic material.

In the embodiment shown in FIGS. 3 to 5, a fixing bolt screwed into the support body 4 is used as the fixing shaft 5, and an upper support member 10 and a lower support member 10 are sandwiched between the end faces of the bunonyu 5, which facilitates assembly. It's Toshide.

In addition, in this embodiment, the bushing 5. A through hole 2 is formed in the receiving member 10 for the dynamic pressure bearing portion between the rotating body 3 and the rotating body 3.
This is so that outside air can easily flow from 0. The back amplifier ring 18, which is a ring-shaped piece of iron, is attached to the magnet 7.
This is to improve the magnetic circuit and to maintain mass balance, and the balance can be corrected without damaging the strength of the rotating body 3 made of ceramics.

In this case, the bolt of the fixed shaft 5 is screwed into the screw hole 21, and the washer 15 and the gasket 19 are used together to enable the holding member 10° 10 to be held in place. A guide air passage 22 communicating with a through hole 20 provided in the lower receiving member 10 is formed. Furthermore, when the magnet 7 is embedded in the insertion hole 8 of the rotating body 3, it can be optionally covered with a synthetic resin coating agent.

Furthermore, in the example shown in FIG. 6, the rotating body 3 is made up of a cylindrical ceramic ring 3I to which a magnet 7 is fixed, and a metal collar 3□ fixed to the outer periphery of the ceramic ring 3I by shrink fit. The outer periphery of the brim 3□ is a polygon mirror 2.

〔Effect of the invention〕

The present invention provides a polygon mirror that includes a magnet provided on a rotating body and a stake coil that is opposed to the magnet and rotates the rotating body, in which the rotating body is rotatably mounted on a bushing fitted to the fixed shaft. At the same time, a groove for generating dynamic pressure is formed on either the outer circumferential surface of the bushing or the sliding surface on the rotating body side facing the bushing, and the rotating body is held between thrust receiving members from both sides, and the bushing is held by the fixing member. It is also fitted onto a fixed shaft, and grooves for generating dynamic pressure are provided on the sliding surface facing the receiving member of this rotating body, which greatly improves the perpendicularity and parallelism of the polygon rotor and prevents rotor center runout. In addition to being as compact as possible, it is easy to assemble and deploy, is robust, and balance adjustment is easy, allowing for stable rotational operation. Even if the thickness of the polygon rotor whose outer peripheral surface is a part of the mirror is thin, the amount of deformation can be reduced, and compared to conventional polygon mirrors, the dimension in the direction of the rotation axis on which the polygon mirror is attached is shorter, significantly reducing the It is possible to make it thinner, smaller, and lighter, and its air resistance can be significantly reduced. It also means that it can achieve the same rotational speed as the conventional model with less power, and it also uses the same amount of power as the conventional model. When inserted, it becomes a polygon mirror that can obtain higher rotational speeds, and because it generates a dynamic pressure effect on the polygon rotor and receives thrust loads well, maintenance and security are easy, and solid contact during startup and shutdown is avoided. Even if there is, it will not wear out,
In addition, the dynamic pressure generation effect when generated is well maintained and can support high thrust loads, so it always functions well as a polygon mirror that stably scans the light beam, and the ceramic sliding member Through the intervention of the present invention, a polygon mirror capable of accurately reflecting laser beams and the like can be obtained in a form that is simple in structure, easy to manufacture, and inexpensive.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIG. 2 is a cut side view of another embodiment, FIG. 3 is a longitudinal sectional view of a part of still another embodiment, and FIG. Figure 5 is the bottom view of the If line.
FIG. 6 is a longitudinal sectional view of a part of another embodiment, and FIG. 7 is a longitudinal sectional view of a conventional example. 1... Through hole, 2... Mirror surface, 3... Rotating body, 4...
...Support, 5...Fixed shaft, 5I...Bouch, 6
... Stator coil, 7... Magnet, 8...
Insertion hole, 1o...receiving member, 11.11. ...Groove for dynamic pressure generation, 12...Cover integrated, 15...Washer, 16.
...fixing nut, 17...spring.

Claims (6)

[Claims] (1) A polygon mirror in which a rotating body with a mirror surface is rotatably provided on a fixed shaft provided on a support body to form a polygon rotor, a magnet is provided on the rotating body, and a stator coil is provided corresponding to the magnet, The rotating body is rotatably fitted into a bush fitted and disposed on the fixed shaft, and a dynamic pressure generating groove is formed on either the outer circumferential surface of the bush or the sliding surface on the rotating body side facing the bush, and the The rotating body is held between thrust receiving members from both sides, the fixed member is fitted onto the fixed shaft together with the bushing, and a groove for generating dynamic pressure is provided on the sliding surface of the rotating body facing the receiving member. Polygon mirror. (2) The rotating body is interposed between receiving members provided on both sides thereof, and is made of a ceramic material with spiral grooves for generating dynamic pressure formed on both sides. The polygon mirror described in item 1. (3) The rotating body is a polygon rotor, which is a flat plate having a regular polygonal outer periphery, and has a mirror surface formed by fixing aluminum foil to the outer periphery. The polygon mirror according to item 1 or 2. (4) Any one of claims 1 to 3, wherein the rotating body is a polygon rotor that is a flat plate with a through hole in the center and has a plurality of annular magnets arranged concentrically with the through hole. Polygon mirror described in two sections. (5) The support body is made of an aluminum material and is used as a receiving member forming an axial dynamic pressure bearing of the rotating body.
The polygon mirror described in any one of item 4. (6) The bushing is pressed and held between the receiving member and a washer provided on the fixed shaft with a coil spring interposed therebetween. polygon mirror.