JP3000339B2 - Rotating polygon mirror - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material and a structure of a rotary polygon mirror (a so-called polycon mirror) used for an optical deflector or the like.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a conventional example of an optical deflector to which a rotary polygon mirror is attached. In the figure, reference numeral 2 is
For example, a frame attached to a main body chassis of a laser beam printer has a fixed shaft 3 provided at the center thereof. The fixed shaft 3 is provided with ball bearings 4a and 4b each fitted with an inner ring at appropriate intervals. A stator core 8 having a plurality of salient poles projecting radially is fixed to the frame 2, and a coil 11 is wound around each of the salient poles. The frame 2, the stator core 8, and the coil 11 constitute a fixed portion of the optical deflector.

On the other hand, the outer rings of the ball bearings 4a and 4b are fitted and fixed in inner holes of the hub 5. Therefore, the hub 5 is rotatably supported on the fixed shaft 3 by the ball bearings 4a and 4b. The hub 5 has a step 5a on which the rotary polygon mirror 1 is placed, and a flange 5b extending outward from the step 5a.
A drive magnet 7 having a cylindrical shape is mounted on the inner peripheral surface of b through a yoke 6 made of a magnetic material. The driving magnet 7 faces the salient pole of the stator core 8 at a predetermined interval. The hub 5, the yoke 6, and the driving magnet 7 constitute a rotating part of the optical deflector.

The rotary polygon mirror 1 has a through hole at the center thereof for engaging with a hub 5 which is a rotating member. The through hole is fitted into the hub 5, and a part of the bottom surface is fitted to a step 5 a of the hub 5. In the abutting state, it is fixed to the hub 5 by the clamper 9 and the fastening member 10.

When the coil 11 wound around the stator core 8 is energized, the drive magnet 7 and the stator core 8
The rotating member is rotated by the electromagnetic action of the above, and the rotating polygon mirror 1 is also rotated at the same time.

If the optical deflector having such a configuration does not rotate stably and smoothly for a long period of time, there is a possibility that defects such as the impossibility of incidence and reflection of a laser beam on a mirror surface at an accurate position may occur. There is. That is, if rotation unevenness or distortion occurs on the reflection surface, the jitter deteriorates, and the laser beam cannot enter or reflect on the mirror surface at an accurate position, which adversely affects the image quality. For this reason, the rotary polygon mirror 1 as well as the rotary member of the optical deflector must be manufactured with high accuracy and economically.

For this reason, the conventional rotary polygon mirror 1 is generally formed by cutting a solid material such as a rolled plate, strip, or extruded rod of A6061 or A5066-based aluminum alloy having high corrosion resistance. there were. And, as the processing method, the primary processing of processing a solid material into a shape close to the final shape to obtain a blank material, and the secondary processing of finishing the blank material and obtaining a finished product of a rotating polygon mirror It is common to take. For example, in the primary processing, using a milling machine or a lathe, etc., after processing the solid material into a disc shape, while drilling a through hole in the center, cutting the outer peripheral surface into a regular polygonal shape, if necessary The blank is formed by chamfering the corner. In the secondary processing, after the inner peripheral surface of the through hole engaging with the hub, the mounting reference surface, and the reflection surface are cut, the reflection surface is further finished with a diamond tool.

As is well known, the shape of the rotary polygon mirror 1 is such that the outer shape from above in the rotation direction is a substantially regular polygon, has a through hole at the center thereof, and has a laser on the side surface. A reflecting surface for reflecting light is formed.

[0009]

As described above, the conventional rotary polygon mirror 1 is formed by first processing a solid material to form a blank material, and then performing a secondary process (finishing process). Therefore, there are the following issues to be solved. Since the rotating polygon mirror 1 is made from solid material, a large amount of offcuts are generated when creating a blank material by primary processing,
Material is wasted. The number of processing steps from primary processing material to secondary processing is very large, and productivity is very low. Solid material does not have good machinability and requires a lot of know-how in cutting conditions such as the shape of the tool edge, cutting depth during cutting, feed speed, etc. to create a reflective surface, and therefore low yield and low cost Is difficult to supply. Since the cutting is performed by applying a cutting tool while turning the solid material, a helical long continuous chip is generated, and the cutting chip is entangled with the cutting edge of the cutting tool, thereby deteriorating the cutting ability. In addition, chips are deposited on the cutting edge of the cutting tool, causing a phenomenon of a constituent cutting edge, which also deteriorates cutting accuracy. Furthermore, since the cutting tool may be missing, it is necessary to constantly monitor the cutting, and it is difficult to make the machining unmanned. In order to reduce the cutting resistance of the cutting tool against the solid material to be cut and to suppress the heat generated during cutting, it is common to pour cutting oil into the machined part during machining. Cleaning is performed using a cleaning agent to remove cutting oil adhering to the surface. For this reason, the manufacturing process becomes longer and cleaning equipment is required.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art. By forming a rotary polygon mirror with a sintered material, material waste can be reduced and material cost can be reduced. While simplifying the processing process,
Further, it is an object of the present invention to provide a rotary polygon mirror capable of improving the machinability at the time of the cutting process and improving the productivity.

[0011]

In order to achieve the above object, in the rotary polygon mirror according to the first aspect of the present invention, the rotary polygon mirror is fixed to a rotating member and rotates integrally with the rotating member. Is made of a sintered material obtained by firing a metal mixed powder obtained by adding at least one of silicon, copper, and magnesium as an additive to aluminum powder as a main component, and having a volume density of 95%. That is all.

According to the second aspect of the present invention, there is provided the first aspect.
In the rotating polygon mirror described, the rotating polygon mirror, in addition to the additives, chromium, iron, manganese, zinc, and baked metal mixed powder obtained by adding at least one or more of each powder of titanium to aluminum powder It is a sintered material.

Further, in the invention according to claim 3, in the rotary polygon mirror according to claim 1 or 2, the rotary polygon mirror is:
The blank material formed into a shape close to the final shape is finished, and this blank material is used as a sintered material. According to a fourth aspect of the present invention, in the rotary polygon mirror according to the first or second aspect, the rotary polygon mirror has a through-hole at the center for engaging with the rotating member, and the inner peripheral surface of the through-hole is non-conductive. It is a cutting surface.

In addition, according to the fifth aspect of the present invention, in the rotary polygon mirror according to the third aspect, a through hole is formed in the blank material so as to be fixed to the rotating member with a fastening member. In the invention according to claim 6, in the rotary polygon mirror according to claim 5, the through hole has a large diameter portion and a small diameter portion concentrically, and the depth of the large diameter portion is greater than the depth of the small diameter portion. Is also deep.

The rotary polygon mirror of the present invention is made of a sintered material of a metal mixed powder. For this reason, this rotary polygon mirror can be sintered in a form close to the final form, and only a small portion requiring precision needs to be finished by cutting or the like. The sintered material is easily cut for finishing, and requires less cutting oil. Further, the chips are powdery, and the chips do not become entangled with the cutting edge of the cutting tool. The density of the sintered material mainly composed of aluminum is high, and the generation of dust and gas caused by the porous material is small, and the strength and hardness are improved and the corrosion resistance is improved by using aluminum as a main component.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a rotary polygon mirror according to the present invention will be described with reference to FIGS. Since there is no characteristic difference between the optical deflector in the conventional example already described and the optical deflector for rotating and driving the rotary polygon mirror of the present invention, the material and structure of the rotary polygon mirror will be mainly described here. .

In the rotary polygon mirror according to the present invention, silicon, copper, magnesium,
It is made of a sintered material obtained by firing a metal mixed powder to which chromium, iron, manganese, zinc, and titanium powders are added. For example, by sintering using the same component as an aluminum alloy of type 6061 in Japanese Industrial Standards (JIS) name,
A sintered metal body having substantially the same properties as 6061 aluminum can be obtained. The 6061-based aluminum contains 0.4 to 0.8% by weight of silicon, 0.15 to 0.4% by weight of copper, and 0.1 to 0.4% by weight of magnesium in addition to aluminum as a main component.
8 to 1.2% by weight, 0.04 to 0.35% by weight of chromium, 0.7% by weight of iron, 0.15% by weight of manganese
An aluminum alloy containing about 0.25% by weight of zinc and about 0.15% by weight of titanium. On the other hand, the present invention is a sintered material obtained by mixing all of these metals with powder and sintering the mixed metal powder.

Not all of the above additive powders to be added to the aluminum powder are essential, and any one of silicon, copper and magnesium is an essential additive. Strength and hardness are improved by adding any of silicon, copper and magnesium. Addition of chromium in addition to these essential additives improves corrosion resistance and hardness. By adding iron, strength, malleability, and ductility are improved. When titanium is added, the weight can be reduced, and the corrosion resistance and hardness are improved. Manganese may be added as a deoxidizing material. Further, by adding zinc as a sintering material component, it is possible to enhance the bonding with a plurality of metals. Accordingly, the rotating polygon mirror may be any one of silicon powder, aluminum powder as a main component, and at least one of powders of any of magnesium, copper, and magnesium as additives, and chromium, iron, manganese, Any one or more of powders of zinc and titanium may be added.

Next, FIG. 1 shows an example of a manufacturing process for obtaining a rotating polygon mirror by sintering a metal mixed powder. First, a raw material powder such as silicon, copper, magnesium or the like is mixed with aluminum powder, and a mixed powder containing aluminum for sintering as a main component, for example, a metal equivalent to 6061-series aluminum in the JIS name consisting of the above-mentioned chemical components Create a mixed powder. Next, this is put into a molding die and pressure-molded into the same shape as a blank material described later, and then sintered in a vacuum to obtain a sintered body. This sintered body is further subjected to a heat treatment step called, for example, T6 treatment and quenched. Thereby, the hardness of the sintered body can be increased. Next, in the sizing step, the inner peripheral surface of the through hole provided at the center of the rotary polygon mirror is plastically worked. Thereby, the roundness of the through hole can be increased. Next, the rotating polygon mirror is subjected to a cleaning step using an ultrasonic cleaner or the like, and a blank material close to the final form as the rotating polygon mirror is manufactured.

FIG. 2 shows an example of the blank material of the rotary polygon mirror manufactured as described above. Since the blank 20 of the rotary polygon mirror is made of a sintered material, it is formed into a shape close to the final shape of the rotary polygon mirror as shown in FIG. That is,
The outer periphery is already formed in a regular polygon (a regular hexagon in the case of the drawing), and a desired roundness is secured on the inner peripheral surface of the central through hole 21 by the sizing process described above. Therefore, the final shape of the rotary polygon mirror can be easily obtained by finishing the outer peripheral surface 24 serving as a mirror surface using the blank material 20 as a workpiece. Therefore, as compared with the case where a final shape is cut out from a solid material as in the related art, the processing step is drastically simplified, and the number of cut end pieces is reduced, thereby eliminating waste of material cost.

Next, another embodiment according to the present invention is shown in FIG. FIG. 3 shows a blank 20 'of a rotary polygon mirror of another shape formed by sintering. In the case of this embodiment, as shown in FIG.
Is provided with a screw-through hole 22 for fixing to a hub at the stage of molding. FIG. 3B shows FIG.
(A) is a cross-sectional view taken along the line xx ′, and shows through holes 22 for screwing.
Has a large-diameter portion 22a and a small-diameter portion 22b concentrically and is provided with a step in the middle. At this time, the large diameter portion 22a
L1 and the depth L2 of the small diameter portion 22b are formed in a relationship of L1> L2. In addition, when t is the total thickness of the blank 20 ′ of the rotary polygon mirror, t = L1 + L
2.

A screw (not shown) is inserted into the through hole 22.
A rotating polygon mirror whose reflection surface 24 is finished is fixed to a hub as a rotating member. Large diameter portion 22a and small diameter portion 22
The head of the screw is tightened against the step b. However, since L1> L2, even if the rotating polygon mirror is slightly deformed by tightening the screw, the reflecting surface 24 is hardly distorted. Images obtained by the scanning of the rotating polygon mirror according to the invention can also be kept at high quality.

The blank 20 shown in FIGS. 2 and 3
As described above, 20 'is formed by molding a metal mixed powder containing aluminum as a main component in a mold and sintering it, so that it is very close to the final shape of the rotary polygon mirror. However, since strict dimensional accuracy is not obtained, a portion requiring strict dimensional accuracy, for example, the reflection surface 24 requires finishing by cutting. However, as described above, since the inner peripheral surface of the center through hole 21 and the through hole 22 for screwing are provided in advance at the stage of forming the blank material, cutting is not required.

When the reflecting surface 24 and the like are finished by cutting, the aluminum-based sintered body according to the present invention has good machinability, and since the chips generated by the cutting are powdery or short, cutting is performed. The powder is not entangled with the cutting edge of the cutting tool, the cutting accuracy is good, and the cutting tool is not chipped. Therefore, there is no need to constantly monitor the processing machine, and the processing can be unmanned. In addition, since the sintered body has good cutting properties, the cutting resistance and heat generation are lower than when cutting a solid material, and the cutting can be performed without using a cutting oil at the time of cutting. For this reason, when washing off the chips adhered to the rotary polygon mirror after finishing, it is only necessary to wash with tap water or pure water, so the process is simplified as compared with using cutting oil, and the cleaning equipment is There is no cost.

The rotary polygon mirror used in the optical deflector is designed to process the laser beam incident / reflective surface with high precision in order to maintain good image quality and to ensure that the reflectivity is equal to or higher than a predetermined value. There must be. Therefore, in the case of a rotary polygon mirror made of a sintered material, a necessary reflectance cannot be obtained unless the average density of the whole is extremely high. In this regard, the rotating polygonal mirror according to the present invention, which is made of a sintered material of a metal containing aluminum as a main component, can have an average density of 95% or more by sintering with the above-mentioned additives. It becomes possible and the required reflectance can be obtained. Therefore, it is possible to obtain the same reflectance as that of a conventional rotary polygon mirror formed by cutting a solid material.

Even if only aluminum powder is sintered or another additive is added to aluminum powder for sintering, a sintered body having a desired density cannot be obtained. The reflectance is reduced, and it is no longer useful as a rotating polygon mirror. ADVANTAGE OF THE INVENTION According to this invention, the average density of the whole sintered material can be set to 95% or more, and by doing so, the reflectance of a reflective surface can be ensured more than predetermined. Also, by setting the average density to 95% or more,
The rigidity of the rotating polygon mirror itself is increased, and the weight balance and the rotating balance are also improved.

Although each of the above embodiments is an example of a preferred embodiment of the present invention, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. Needless to say, For example, in the above-described embodiment, a regular hexagonal rotating polygonal mirror has been described. However, the present invention is not limited to a regular hexagon, and any regular polygon such as a regular pentagon or regular octagon may be applied. Instead of a strictly geometric regular polygon, for example, a regular polygon in which each corner is chamfered may be used. Further, in the above embodiment, a ball bearing is used to support the rotating member of the optical deflector.
Other bearings, such as a dynamic pressure bearing and a plain bearing, may be used.

[0028]

As described above, the rotary polygon mirror according to the first aspect of the present invention is characterized in that one or more powders of silicon, copper, and magnesium are added to aluminum powder as a main component as an additive and fired. By using a sintered sintered material and having a density of 95% or more, waste of materials can be reduced and material costs can be reduced, and the processing steps can be simplified. In addition, since the sintered material has good machinability, the processing accuracy is stable, the yield is improved, and the rotary polygon mirror can be supplied inexpensively and in large quantities.

In the rotary polygon mirror according to the second aspect, the strength and hardness are improved by adding any of silicon, copper and magnesium as an additive. The addition of chromium improves corrosion resistance and hardness. On the other hand, the strength, malleability, and ductility are improved by adding iron. When titanium is added, the weight can be reduced, and the corrosion resistance and hardness are improved. Also, adding manganese has a deoxidizing effect,
Further, by adding zinc as a sintering material component, it is possible to enhance the bonding with a plurality of metals.

In addition, in the rotary polygon mirror according to the third aspect,
Since the rotating polygon mirror is formed by finishing the blank of the sintered material, the blank material can be obtained in a shape close to the final shape in advance by sintering, so that the working process is simplified and the productivity is increased.

Further, in the rotary polygon mirror according to the fourth aspect,
The through hole engaged with the rotating member can be formed integrally during sintering, and the processing step is simplified.

In the rotary polygon mirror according to the fifth aspect, since a through hole for screwing is also formed at the stage of forming the blank material, the step of forming the through hole can be omitted. Furthermore, in the rotary polygon mirror according to the sixth aspect, the through hole for screwing is constituted by a concentric large diameter portion and a small diameter portion, and the depth of the large diameter portion is longer than the depth of the small diameter portion. Even if the rotating polygon mirror is slightly deformed due to the tightening of the screw, the reflecting surface is hardly distorted, and therefore, the image obtained by scanning the mirror surface of the rotating polygon mirror according to the present invention can be maintained at high quality. As a result, an economical and highly reliable rotating polygon mirror can be provided.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a manufacturing process of a rotary polygon mirror according to the present invention.

FIG. 2 is a perspective view showing an example of a blank material serving as a rotary polygon mirror according to the present invention.

FIGS. 3A and 3B are views showing another embodiment of the rotary polygon mirror according to the present invention, wherein FIG. 3A is a perspective view and FIG. 3B is a cross-sectional view along xx '.

FIG. 4 is a sectional view of an embodiment of a conventional optical deflector.

[Explanation of symbols]

 20, 20 'Blank material 21 Through hole 22 Through hole 24 Outer peripheral surface (reflective surface)

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 26/10 102 G02B 5/08

Claims (6)

(57) [Claims] 1. A rotating polygonal mirror fixed to a rotating member and rotating integrally with the rotating member, the rotating polygonal mirror is composed of aluminum powder as a main component, silicon,
A rotary polygon mirror comprising a sintered material obtained by firing a metal mixed powder to which at least one powder of copper or magnesium is added as an additive, and having a volume density of 95% or more. 2. The rotating polygon mirror further comprises, in addition to the additive,
2. The rotating polygon mirror according to claim 1, wherein the rotating polygon mirror is made of a sintered material obtained by firing a metal mixed powder obtained by adding at least one of chromium, iron, manganese, zinc, and titanium powders to an aluminum powder. . 3. The rotating polygon mirror is obtained by finishing a blank material formed in a shape close to the final shape, and the blank material is made of a sintered material. The rotating polygon mirror according to claim 2. 4. The rotary polygon mirror according to claim 1, wherein the rotary polygon mirror has a through hole in the center thereof for engaging with the rotating member, and an inner peripheral surface of the through hole is a non-cut surface. 2. The rotary polygon mirror according to 2. 5. The rotary polygon mirror according to claim 3, wherein a through hole is formed in the blank material so as to be fixed to the rotating member with a fastening member. 6. The rotary polygonal surface according to claim 5, wherein the through hole has a large diameter portion and a small diameter portion concentrically, and the depth of the large diameter portion is greater than the depth of the small diameter portion. mirror.