JPS6392915A - Rotary polygonal mirror - Google Patents

Abstract

PURPOSE:To attain rapid rotation and to improve abrasion resistance by forming at least one of upper and lower faces of a rotary polygonal mirror as a face supporting thrust load and forming at least a part of the supporting face with a ceramic. CONSTITUTION:The rotary polygonal mirror 10 is supported by at least one of its upper and lower faces without being supported only by a rotary shaft 12. In this case, at least a part of the face supporting the thrust load is formed with a ceramic 20. It is preferable to set up the porosity of the porous ceramic body to 10-60% by volume. On the other hand, the diameter of an opened pore is preferably set up to <=10mum. Consequently, an excellent property in the abrasion resistance of the ceramic 20 and high strength can be sufficiently displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rotating polygon mirror that is a reflecting mirror used in laser beam printers, optical instruments, and the like.

(Prior Art) This type of rotating polygon mirror (also called a polygon mirror) has recently attracted attention as a device that reflects laser beams, or it has a polygon mirror structure in which the circumference is divided into equal parts. In order to identify characters, defects, etc. by scanning the photosensitive drum of a laser beam printer with a laser beam, or by scanning a sheet of paper or a steel plate with a laser beam,
It is used by being rotated at a very high speed by a drive motor. (See Figure 7) In the conventional 4II structure of this type of rotating polygon mirror, the reflective mirror part is sometimes made of metal such as aluminum to ensure heat resistance and strength against high-speed rotation. In many cases, a rotating shaft is inserted and fixed in the center of the rotating shaft, and the rotating shaft is used to rotate at high speed. In other words, the rotating polygon mirror is designed so that its load is applied to the rotating shaft, and when the mirror is in use, the load is concentrated on the rotating shaft.

Unless the material and structure of the rotating shaft are considerably limited, it will not be able to withstand the necessary high-speed rotation.

In other words, in a rotating mirror that uses a rotating shaft,
Since the load of this rotating polygon mirror is supported by a single rotating shaft, it is necessary to devise measures to prevent friction from occurring at the bearing part of the rotating shaft, which makes the structure complex, and the high-speed rotation Due to the necessity of
For this reason, even if structural or material improvements are made, the maximum rotational speed of conventional rotating polygon mirrors of this type that supports the load using a rotating shaft is limited to a relatively low speed of about 16,000 rpm. It was something that existed. However, with recent technological developments, the rotational speed of the rotating polygon mirror has been required to be even faster, for example, 30,000 rpm or more.

In order to deal with this situation, the inventor of the present invention has conducted intensive research and has developed a support structure for this type of rotating polygon mirror, which supports the upper and lower surfaces of the rotating polygon mirror instead of the conventional support structure using bearings. By supporting the thrust load on at least one of the surfaces and by using ceramics with excellent wear resistance for the supporting part, the rotation speed of this type of rotating polygon mirror can be increased to the extremely high speed range that has been required in recent years. The present invention was completed based on the new finding that it is possible to obtain a rotating polygon that can be rotated easily.

(Problems to be solved by IJ'l) The present invention has been made in view of the above circumstances.

The problems to be solved are the limit of the rotational speed of the rotating polygon mirror, which is rotated at high speed, and the problem of its durability.

The purpose of the present invention is to
It can withstand rotations of more than m and is J9 resistant! To provide a rotating polygon mirror having an IPil shape and having excellent wear resistance and durability.

(Means for Solving the Problems) The means taken by the present invention to solve the following problems will be explained with reference to FIGS. 1 to 6 corresponding to the embodiments. In a rotating polygon mirror including a reflecting mirror (11) on its surface.

This rotating polygon mirror has at least one of its upper and lower surfaces supporting a thrust load, and at least a part of the surface supporting the thrust load is formed of ceramics (20). It is a polygon mirror (10) J.

That is, the rotating polygon mirror (10) according to the present invention is not supported only by the rotating shaft (12) as in the conventional case, but is supported by at least one of its upper and lower surfaces, as shown in FIG. is the surface that supports the thrust load, and the load of the rotating polygon mirror (10) is supported by at least one of the upper and lower surfaces of the rotating polygon mirror (]0). It is something. Note that the rotation axis (12) of the rotating polygon mirror (10) shown in FIG.
is not arranged to support a load, but is used to define the center of rotation of the rotating polygon mirror (10) itself, and this rotation axis (12) is actually a rotating polygon of π. It does not support the load of the chain (10) at all.

In addition, as shown in FIGS. 1 and 2, the surface supporting the thrust load on the rotating polygon m(10) is -
Although there are cases where only the surface is targeted, the rotating polygon mirror (1
0) is horizontal, for example, as shown in Figs. It may be implemented as follows.

In the present invention, part of the surface that supports this thrust load is formed of ceramics (20). The reason why at least a part of the surface that supports this thrust load is formed of ceramic (20) is that the ceramic (20) provides wear resistance during contact sliding and improves durability. This is because at least the portion on which the load is applied may be made of ceramics. Therefore, there are various possible structures for forming the ceramic (20) on the surface that supports the thrust load. Of course, when forming this ceramic (20) in :tS
As shown in 3 [¥1], the reflection m(11) and the center portion may be formed of metal aluminum, and the reflection may be formed partially on both surfaces.

In addition, as shown in 4I21 and FIG.
Of course, it is also possible to form the peripheral portion where II) is formed from metal aluminum and the central portion from ceramics (20).

In any of the above cases, the metal aluminum and each ceramic (20) may be joined by simple adhesion or by mechanical means such as screws or bottles. Furthermore, this rotating polygon mirror (10) can also be formed entirely of ceramics (20).

Various materials can be used for such ceramics (20), among which Al t Ox, 5iOz
, ZrO2, SiC, TiC, TaC1B4 C, Cr
z c2. Si3N4, BN, TiN, AfLN, T
iBz, CrB2. ZrB2. A material mainly containing at least one selected from cordierite, mullite, T i O2, or these compounds can be used.

These specifically listed ceramic materials are of this type with rotating polygons! (10) It has various advantages such as ensuring durability, processing, and easy availability of materials. In addition, as for the ceramic (20) formed of such a material, m=
Of course, if it is of high quality.

It is also possible to use a porous material (e).

When a porous ceramic is used as the ceramic (20), it is suitable that the pores are filled with a lubricant. 1t1. during contact sliding due to the lubricant filled in the open pores. This is because the generation of vibration force can be reduced. Therefore, when a porous ceramic is used as the ceramic (20), it is suitable to have open pores or a three-dimensional network structure so that lubricant can be easily filled.

Ceramics (2) used for the rotating polygon m (10)
The reason why a porous material with open pores filled with lubricant is suitable as 0) is that ceramics (20) generally have excellent wear resistance by themselves or have poor self-lubricating properties. However, porous ceramic νx (20), which has open pores filled with lubricant, has the disadvantage of a relatively large coefficient of friction.

This is because the lubricant filled in the open pores can provide self-lubricating properties.

In this case, the porosity of this ceramic porous body is lO~
It is preferable that the porosity is 60% by volume, because if the porosity is smaller than the IO volume%, even if the lubricant is filled, the ceramic (2
This is because the sliding area of 0) is larger, so the lubricant cannot fully exert its effect. On the other hand, the porosity of open pores is 6
If it is larger than 0.06% by weight, the lubricity effect is sufficient, but the strength of the ceramic porous body decreases and the load bearing capacity decreases. % is more preferable.

Further, it is preferable that the diameter of the open pores formed in this porous ceramic (20) is 10 pm or less. The reason is that when each pore diameter is greater than or equal to loJLm,
As described above, although the efficiency of filling the open pores with the lubricant is sufficient, the strength of the ceramic porous body itself decreases and the load bearing capacity decreases.

Note that ceramics, porous ceramics, metal, or the like can be used for the member constituting the surface opposite to the surface supporting the rotating polygon mirror (lO).

The lubricants to be filled into the open pores of the porous ceramic body as described above include fluorine oil, silicone oil, mineral oil, animal and vegetable oil, paraffin oil,
It is preferable that at least one selected from naphthenic oils is selected from the above-mentioned ceramics (2).
It is easily impregnated into the pores of 0), reacts sensitively to slight frictional heat during startup, has a low viscosity, and is supplied to the sliding surface between the # bearing and the journal by the pumping effect.

This is to significantly reduce the starting torque, and among other things,
It is more effective to use at least one selected from fluorine-based oil, silicone-based oil, paraffin-based oil, and naphthenic oil.

In addition, examples of the lubricant filled in the open pores of the above-mentioned porous ceramic body include polyacetal resin, polyamide resin, polyethylene resin, polycarbonate resin, polybutylene terephthalate resin, and styrene acrylonitrile resin.

The reason why these lubricants can be used is that they can use at least one selected from polypropylene resin, polyurethane resin, polyphenylene sulfide resin, silicone SL fat, or fluororesin. It is a lubricant that exhibits an excellent solid state, has extremely little loss in the pores of the ceramic porous body, and maintains excellent sliding properties over a long period of time. Among these lubricants, it is effective to use at least one selected from polyacetal resin, polyamide resin, polyethylene resin, polycarbonate 4J4 resin, or fluorine 4AIm. , ceramic (20) is used to increase the bonding strength between the resin and ceramic (20).
It goes without saying that the surface of 0) can be treated with a silane coupling agent or the like.

Furthermore, as lubricants other than those mentioned above, graphite, black iQ toxide, BN, and molybdenum disulfide are used.

Tungsten disulfide, lead oxide, phthalocyanine, CdC
9,2, tungsten selenide, molybdenum selenide,
Niobium selenide, graphite intercalation compound, CdfL2
, gold, silver, lead, tin, and indium. All of these lubricants have excellent lubricity under various harsh conditions, such as temperatures ranging from extremely low temperatures to oxidation and orphan atmospheres, and are highly effective against the corrosion, heat, and acid resistance of ceramics (20). It is effective in imparting load-bearing properties under harsh conditions without sacrificing excellent properties such as chemical resistance. Among these, it is more preferable that at least one selected from graphite, fluorinated graphite, graphite, BN, molybdenum disulfide, and tungsten disulfide is filled. In order to firmly fix this lubricant in the pores, there are methods using low-melting point glass, frit, or inorganic binders such as viscosity, thermosetting resins such as phenol resin, thermoplastic resins, or phenol resins. Carbonized amorphous carbon or the like may also be used.

Of course, any of the above lubricants can be used alone, but oil, resin, and solid lubricants can also be used simultaneously on ceramics (
20) may coexist in the pores.

It is preferable that the radial lubricant is filled in the pores of the ceramic (20) in an amount of at least IO volume %. The reason for this is that if the IO capacity increase is also small, it becomes difficult to fully demonstrate its lubrication effect, and among these, 3
It is more effective that the content is 0% by volume or more.

In addition, methods for filling the lubricant into the pores include a method of heating the lubricant to melt it and impregnating it, a method of dissolving it in a solvent and impregnating it, a method of impregnating it with a sulfur or a reaction raw material and then reacting it. There is a method in which the atomized lubricant is suspended or emulsified in a dispersion medium and then dried to remove the dispersion medium. Two or more methods can be used together, or the process can be carried out in several batches. It can also be filled.

Furthermore, as shown in FIG. 6, the surface supporting the thrust load has a spiral dynamic pressure group lI! at a depth of 3 to 50 JLm on its sliding surface. ￥ (21). In this way, this dynamic pressure group groove (21)
), the rotating polygon mirror (10) can be suspended using dynamic pressure, and during high-speed rotation there is a direct contact between the surface supporting the thrust load and the surface opposite to the surface supporting the thrust load. This is because it is possible to prevent chafing from occurring.

The reason why it is preferable that the depth of the dynamic pressure group groove on the sliding surface is 3 to 50 pm is that the spiral dynamic pressure group groove (
21) If the depth is less than 3 gm, the dynamic pressure effect may be weak, but
During use, the spiral grooves become clogged with abrasion particles, which deteriorates their performance.
) This is because 1N problems arise, such as uneconomical grinding of the material.

On the other hand, if the depth of the spiral dynamic pressure group groove (2I) exceeds 50 JLm, a sufficient dynamic pressure effect cannot be exerted.

(Actions of the Invention) The present invention has the following effects by adopting the above-described measures.

In other words, since this rotating polygon mirror (10) has at least one of its upper and lower surfaces supporting the thrust load, the load on the S + "J rotating polygon m (10) is the thrust load. It is supported on the support surface of and rotates &!!
It is not necessarily necessary to devise the strength of (12) and the materials and structures to ensure this.

In addition, in this rotating multifaceted ta (10), a part of the thrust load supporting surface, that is, the part that actually makes sliding contact, is formed of ceramics (20).
The excellent abrasion resistance and high strength of the ceramic (20) are fully exhibited without impairing the function of each reflecting mirror (1+) for reflecting the laser beam.

An example of a method for manufacturing a rotating polygon mirror (lO) according to the present invention will be explained in detail below according to examples.

(Example) A silicon carbide porous body serving as a ceramic (20) forming 4 g of a part of the rotating polygon mirror (lO) shown in FIG. 6 was manufactured in the following manner.

(1) Molding process After molding the entire silicon carbide powder (average particle size 0.15 m) into a disc shape, the resulting formed body is fired in a high-temperature oven at normal pressure to create a disc-shaped porous body. Then, the surface of this porous body (g
The area where the groove for generating J pressure should be machined was finished by lapping to make it a smooth flat surface with less waviness.

(2) Pre-treatment step The smooth silicon carbide porous holder disk obtained in the above molding step was washed with trichlene and degreased by immersing it in a 20% mold NaOH aqueous solution at 90 to 100° C. for 5 minutes.

The degreased vk was washed with warm water at 50°C for 5 minutes, then neutralized with an aqueous solution of 10% H, So4, and further washed with warm water at 60°C.

(C) Coating process A cinnamate ester resin (rOFRRJ manufactured by Tokyo Ohka Kogyo Co., Ltd.) is used as the liquid photosensitive resin, and an appropriate amount of toluene is added as a solvent to adjust the viscosity to create a clean disk surface. It was applied to. In addition, the viscosity when using pIi cloth is lO
5 ops, and 5 to 5 ops when dipping the disc.
A viscosity of 20 PS was suitable.

(4) Pre-curing process The disk coated with the liquid photosensitive resin was kept at 100°C for 15 minutes to cure it. The thickness of the photosensitive resin layer can be made to a desired thickness by repeating the coating process and the curing process. A pre-cured photosensitive resin was formed on the surface of the disc.

(5) Exposure process A disk covered with pre-cured photosensitive resin is set in an exposure jig, a pattern film is set on this disk, and an ultra-high pressure mercury lamp is used to expose it to 50 mJ/crn' light. 30
Exposure for seconds.

This pattern film has a spiral pattern formed in advance, so when exposed under an ultra-high pressure mercury lamp, the photosensitive resin layer under the transparent part of the pattern film will be irradiated with light.

(5) Pattern forming process After exposure, it is treated with a developer at 25°C for 2 minutes to react with the photosensitive resin in the exposed areas to develop a spiral pattern, and then the unexposed photosensitive resin layer is removed. did.

(7) Grooving process The surface of the ceramic disk after the pattern forming process in which the surface is combined with a spiral pattern resin layer has an f average grain size of 700.
The average depth is approximately 10 pm using mesh silicon carbide particles.
Shot blasting was performed so that

(8) Stripping process The resin layer is immersed in a special stripping solution of methylene chloride maintained at 25°C for 2 minutes, and the surface is washed with warm water to remove the surface on which the hydrodynamic pressure group grooves for generating dynamic pressure have been formed. did.

(9) Lubricant impregnation process The disk-shaped porous body formed as described above is immersed in oil (lubricant) whose viscosity has been reduced by heating under vacuum or pressure. The oil was impregnated into the open pores of the mass. The oil used in this case was a fluorine oil selected from fluoroethylene, fluoroester, fluorotriazine, perfluoropolyether, fluorosilicone, derivatives thereof, or polymers thereof.

(10) Joining process of ceramics and reflective mirror In order to integrally join the ceramic (20) formed as described above and the metal aluminum for forming the reflective mirror (11), the The ceramic (20) was fixed to a predetermined position on metal aluminum. In this step, the two may be mechanically fixed using screws, pins, or the like, or may be carried out by shrink fitting. In the case of a process that adopts this method, the two may be joined at the final stage, but in order to protect the lubricant impregnated into the open pores of the ceramic (20), it is necessary to ) The lubricant impregnation step may be carried out at a stage before the lubricant impregnation step.

Then, each reflecting mirror (11) was mirror-finished using a conventional method. As a method for forming the reflecting mirror (11), in addition to this mirror finishing, methods such as A-plating, plating, or adhesion of a metal that will become a mirror surface can also be adopted. Such methods such as vapor deposition, plating, or adhesion are effective when the rotating polygon mirror (10) is entirely formed of ceramics.

(Effects of the Invention) As detailed above, in the present invention, as exemplified in the above embodiments, [a rotating polygon mirror in which a reflecting mirror (II) is provided on the outer peripheral surface].

This rotating polygon mirror has at least one of its lower surfaces supporting a thrust load, and at least a portion of the surface supporting the thrust load is formed of ceramics (20). This feature makes it possible to rotate at speeds of 301° or higher, and also to provide a rotating polygon mirror with excellent abrasion resistance and durability with a simple structure. .

In other words, by making at least one of the upper and lower surfaces of the rotating polygon mirror a surface that supports the thrust load, it is possible to prevent the load from concentrating on the rotating polygon mirror, and also to prevent the load from concentrating on the surface that supports the thrust load. By using ceramics with excellent wear resistance, it is possible to provide a rotating polygon mirror with a simple structure that can be used for a long time and has excellent durability.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the rotating polygon mirror according to the present invention in a supported state, Fig. 2 is a perspective view of the rotating polygon mirror, and Figs. A sectional view corresponding to FIG. 1 showing examples in which the configuration of the ceramics is changed in various ways, and No. 61'4 is an example in which a dynamic pressure group groove is formed on the side of the ceramic that supports the thrust load. FIG. 7 is a perspective view showing an example of the configuration of a laser printer using this type of rotating polygon mirror. Explanation of symbols 10... Rotating polygon mirror, 11... Reflecting mirror, 12...
Rotating shaft, 20...Ceramics, 2T...Dynamic pressure croup groove.

Claims (1)

[Claims] 1) A rotating polygon mirror having a reflecting mirror on its outer peripheral surface, wherein at least one of the upper and lower surfaces of the rotating polygon mirror supports a thrust load. , and at least a part of the surface that supports this thrust load is formed of ceramics. 2), the ceramics are Al_2O_3, SiO_
2, ZrO_2, SiC, TiC, TaC, B_4C,
Cr_3C_2, Si_3N_4, BN, TiN, Al
The rotating polygon mirror according to claim 1, which mainly contains at least one selected from N, TiB_2, CrB_2, ZrB_2, cordierite, mullite, TiO_2, or compounds thereof. 3) The rotating polygon mirror according to claim 1 or 2, wherein the ceramic is a porous sintered body having open pores with a three-dimensional network structure. 4) The rotating polygon according to any one of claims 1 to 3, wherein the rotating polygon mirror has a dynamic pressure group groove with a depth of 3 to 50 μm on the surface that supports the thrust load. mirror.