JP2011033754A - Polygon mirror, optical deflector, optical scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polygon mirror capable of preventing the contamination of the reflection face of the polygon mirror due to the adsorption of environmental dust and partial reduction in reflectance by a transparent protection film having excellent antistatic characteristics, and also capable of being used to be recycled. <P>SOLUTION: The polygon mirror 101 is made of aluminum or an alloy including aluminum as a base material, a plurality of reflection faces 105a, 105b which reflect light from a light source are formed on the base material by a cutting work, and the transparent protection film is formed on the reflection faces. The transparent protection film has electric resistance of 1×10<SP>10</SP>Ωm or smaller and hydrophilic property reduced to the contact angle with water of 10° or smaller. Thus, the transparent protection film works as a conductive body or a semiconductor for static electricity, and the adsorption of dust due to charging and the contamination of the reflection faces are prevented. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polygon mirror used for an optical deflector of an optical scanning type digital writing optical system, and more specifically, an optical deflector using the polygon mirror, an optical scanning device using the optical deflector, and The present invention relates to an image forming apparatus such as a digital copying machine, a printer, a plotter, a facsimile, or a complex machine using the optical scanning device as a writing optical system.

Various proposals have heretofore been made regarding polygon mirrors, optical deflectors using the same, optical scanning devices, and image forming apparatuses. For example, the following are known.
Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-125890) states that “a reflectance adjusting film made of SiO ₂ is formed on the surface of a reflecting surface made of aluminum or an alloy containing aluminum, and the thickness of the reflectance adjusting film is A “polyhedral reflector having a thickness of 40 to 80 nm” is disclosed.
Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-131682) describes “a polygon mirror in which an amorphous fluororesin film is formed on a reflective surface by a wet film forming method, an optical scanning device including the polygon mirror, and an electrophotographic apparatus. The configuration is disclosed.
In Patent Document 3 (Japanese Patent Laid-Open No. 2008-33135), “a polygon scanner 140 serving as a deflection scanning unit is directly attached to a housing, and a heat radiating device 170 is attached to a portion facing the polygon scanner on the outer peripheral surface of the housing”. Further, it is disclosed that “the air flow path is formed by providing wall portions 91 a and 91 b extending in the air flow direction by the intake fan as the air blowing means and facing each other with the heat radiation means 170 interposed therebetween”.
Patent Document 4 (Japanese Patent Application Laid-Open No. 1-196018) states that “the upper portion of the cover 30 (the position corresponding to the extending direction of the rotary shaft 36) is provided with an air inflow hole 42 and the lower portion of the peripheral surface of the cover. Is provided with an air outflow groove 44 over substantially the entire circumference (a position corresponding to the radial direction of the base of the rotating shaft 36), "the filter 46 is attached to the air inflow hole 42, “It prevents the inflow of dust and dust into the cover”.
In Patent Document 5 (Japanese Patent No. 3192271), “having an optical box containing a polygon mirror rotated by a motor and having an air inlet with an exhaust port and a filter, and while the rotation of the polygon mirror is stopped, A configuration is disclosed in which a flexible seat valve that opens and closes the exhaust port by being closed by the air pressure in the optical box while the exhaust port is closed is attached to the exhaust port.

Patent Document 1 and Patent Document 2 described above disclose that a protective film is formed on the reflection surface of a polygon mirror. However, conventional protective films made of SiO, SiO _2, or amorphous fluororesin are There is a problem that the dust adsorbs and becomes extremely dirty.
On the other hand, in the optical scanning device used in the image forming apparatus, the temperature rises around the optical deflector due to heat generated by the rotation of the polygon mirror, and a temperature distribution (temperature difference) occurs in the optical box. The temperature rise and temperature distribution in the optical box becomes a variation factor of the shape or the fixed position of optical parts such as a scanning lens and a mirror, and causes an image position shift of the light beam on the photosensitive member and image deterioration.

An optical deflector and an optical scanning device provided with a cooling means against heat generated by rotation of a polygon mirror are disclosed.
For example, Patent Documents 4 and 5 described above disclose a configuration in which an air inlet with a filter is provided above a polygon mirror and an exhaust port is provided below.
However, in the above prior art, as shown in FIG. 10 or FIG. 11, a circulating flow is generated around the polygon mirror (27 or 15), and sufficient inflow of outside air cannot be obtained, and the pressure in the optical box is not obtained. Therefore, the air discharge and the accompanying cooling effect could not be sufficiently obtained. In addition, fine dust that has flowed into the optical box through the gap between the cover and gaseous contaminants that could not be removed by the filter are attached to the polygon mirror in the circulating flow generated around the polygon mirror, and the polygon mirror surface. There was a problem of clouding.

In recent image forming apparatuses, in order to reduce the environmental load, many toners are fixed at a low temperature. However, wax particles dispersed in the toner are also soluble at a low temperature. It may stay inside and become a causative substance of the polygon mirror. In the conventional polygon mirror, an inorganic film such as SiO or SiO ₂ is formed as a protective film, but the wax may adhere to the reflecting surface and cause a decrease in reflectance.

  The present invention has been made in view of the above-described problems of the prior art. A transparent protective film having excellent antistatic properties prevents contamination of the polygon mirror reflecting surface due to adsorption of surrounding dust and partial reduction in reflectance. An object of the present invention is to provide a polygon mirror that can be recycled and used, and furthermore, an optical deflector using the polygon mirror, an optical scanning device using the optical deflector, and an optical scanning device therefor An object of the present invention is to provide an image forming apparatus using the above in a writing optical system.

In order to achieve the above object, the present invention employs the following solutions.
According to a first solution of the present invention, aluminum or an alloy containing aluminum is used as a base material, and a plurality of reflective surfaces that reflect light from a light source are formed by cutting on the base material, and the reflective surface is transparent. In the polygon mirror in which the protective film is formed, the transparent protective film has an electrical resistivity of 1 × 10 ¹⁰ Ωm or less and has a hydrophilicity of 10 ° or less in terms of a contact angle with water. (Claim 1).
According to a second solving means of the present invention, in the polygon mirror of the first solving means, the transparent protective film is a transparent protective film in which conductive fine particles are dispersedly arranged in silicon dioxide (SiO ₂ ). It is characterized (claim 2).

According to a third solving means of the present invention, in the polygon mirror of the second solving means, the conductive fine particles are an oxide-based transparent conductive material.
According to a fourth solving means of the present invention, in the polygon mirror of the second solving means, the conductive fine particles are a carbon nanomaterial.

According to a fifth solving means of the present invention, in the optical deflector in which the rotating body to which the polygon mirror is fixed is supported by the bearing, the polygon mirror is the polygon mirror of any one of the first to fourth solving means. (Claim 5).
According to a sixth solving means of the present invention, in the optical deflector of the fifth solving means, the main part of the rotating body to which the polygon mirror is fixed is composed of a conductive member made of metal, and the bearing is And a fluid dynamic pressure bearing supported in the radial direction and a thrust bearing supported in the axial direction, wherein the electrical resistivity of the fixed side member of the thrust bearing is 1 × 10 ¹⁰ Ωm or less. Item 6).
According to a seventh solving means of the present invention, in the optical deflector of the fifth solving means, the main part of the rotating body to which the polygon mirror is fixed is composed of a conductive member made of metal, and the bearing is The fluid dynamic pressure bearing supported in the radial direction and the thrust bearing supported in the axial direction are characterized in that the electrical resistivity of the lubricating oil of the fluid dynamic pressure bearing is 1 × 10 ¹⁰ Ωm or less ( Claim 7).

  According to an eighth aspect of the present invention, a light beam from a light source is guided to a surface to be scanned via an optical system including an optical deflector to form a light spot on the surface to be scanned. In the optical scanning device which scans the scanning line by the light spot on the surface to be scanned by deflecting the light beam, the optical deflector is an optical deflector of any one of the fifth to seventh solving means. (Claim 8).

According to a ninth solving means of the present invention, a latent image is formed on a photosensitive surface of an image carrier made of a photosensitive medium by optical scanning with an optical scanning device, and the latent image is visualized with toner of a developing means. In the obtained image forming apparatus, the optical scanning device according to claim 8 is used as an optical scanning device for optically scanning the photosensitive surface of the image carrier (claim 9).
According to a tenth solving means of the present invention, in the image forming apparatus according to the ninth solving means, the toner used in the developing means is a toner in which wax fine particles are dispersed. 10).
The eleventh solving means of the present invention is the image forming apparatus according to the ninth or tenth solving means, wherein the toner image visualized on the image carrier is transferred to a recording material directly or via an intermediate transfer member. The toner image transferred to the recording material is fixed by a heat fixing unit to form an image, and a duct or a flow path connected from the vicinity of the heat fixing unit to the optical deflector is provided ( Claim 11).

In the polygon mirror of the present invention, the transparent protective film formed on the reflecting surface has an electrical resistivity of 1 × 10 ¹⁰ Ωm or less and has a hydrophilicity of 10 ° or less in terms of a contact angle with water. The transparent protective film acts as a static electricity conductor or semiconductor, and can prevent dust adsorption and contamination of the reflecting surface due to charging.
That is, in the polygon mirror of the present invention, the transparent protective film having excellent antistatic properties can prevent the polygon mirror reflecting surface from being soiled and partially reduced in reflectance due to the adsorption of surrounding dust. In addition, by providing hydrophilicity, the surface of the protective film is covered with water molecules to enhance the antistatic effect, and it is easy to remove dirt by water washing after aged use, and the polygon mirror can be reused. .

  In the optical deflector of the present invention, by using the polygon mirror described above, it is possible to provide an optical deflector with little contamination and fogging of the polygon mirror and a small decrease in reflectance over a long period of time. Further, by imparting hydrophilicity to the transparent protective film of the polygon mirror, it is possible to easily remove the dirt adhering to the reflecting surface, and it is possible to recycle the rotating body including the polygon mirror.

  In the optical scanning device of the present invention, by using the above optical deflector, there is provided an optical scanning device in which the decrease in the reflectivity of the polygon mirror is small and the difference in light utilization efficiency due to the difference in image height position is small over a long period of time. can do.

  In the image forming apparatus of the present invention, the above-described optical scanning device is used to prevent fogging and contamination of the polygon mirror surface, and there is no reduction or variation in the reflectance of the polygon mirror reflecting surface, and the image height position over a long period of time. Therefore, it is possible to provide a high-quality image forming apparatus that does not cause unevenness in image density due to the difference.

It is sectional drawing of the optical deflector using the polygon mirror which shows the 1st Example of this invention. FIG. 5 is an explanatory diagram illustrating a configuration of an optical scanning device according to a second embodiment of the present invention. It is a perspective view which shows the external air induction rectification member and polygon mirror of the optical scanning device shown in FIG. It is a schematic sectional drawing of the optical scanning device which shows the 3rd Example of this invention. FIG. 5 is a perspective view showing an outside air induction rectifying member and a polygon mirror of the optical scanning device shown in FIG. 4. It is an enlarged view of the filter of the external air induction rectification member shown in FIG. It is a principal part perspective view of the filter shape-processed by the honeycomb form. It is a schematic block diagram of the image forming apparatus which shows the 4th Example of this invention. It is a schematic block diagram which shows the example which changed the duct shape of the image forming apparatus shown in FIG. It is a figure which shows an example of a prior art, Comprising: It is a schematic sectional drawing of an optical deflector. It is a figure which shows another example of a prior art, Comprising: It is a schematic principal part sectional drawing of an optical deflector. It is explanatory drawing of the generation | occurrence | production part of the cloudiness of a polygon mirror, and dirt. It is explanatory drawing of the negative pressure part of the reflective surface of a polygon mirror.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the cause of contamination of the polygon mirror will be considered.
As shown in FIG. 12, the polygon mirror is fogged or dirty, as shown in FIG. 12, when two or three sides of the polygon mirror rotate to one side, the back side of the surface that cuts the wind (for example, the left side of one side) The present inventors have confirmed through experiments that fogging and smearing occur around a portion (for example, the right side portion of two surfaces).
Further, in the process of elucidating the cause of cloudiness and dirt, as shown in FIG. 13, when the polygon mirror rotates, air is pushed out to the outside on the surface that cuts the wind (for example, the left side of one surface), and the back side ( The air flow analysis simulation around the polygon mirror revealed that the pressure on the right side of the two surfaces was negative and air was supplied from above and below the polygon mirror.
In other words, dust and gaseous contaminants contained in the air above and below the polygon mirror gather at the negative pressure part of the polygon mirror, adhere to the reflective surface, and solidify (sublimation from gas to solid). The result that can be presumed to be the cause was obtained.

In the deposition of suspended particles (particle size of 10 μm or less) on the surface of an object, three main forces are involved: electrostatic force (Coulomb force), gravity, and Brownian diffusion. In the case of a polygon mirror that rotates at high speed, collisions between the wind-cut surface and pollutants can be considered, but rather the dirt on the reflective surface on the back side of the wind-cut surface is significant, and the influence of electrostatic force generated by friction with pollutants or air. Is the largest.
In an experiment using paraffin wax having a high electrical resistivity of 1 × 10 ¹⁴ to 10 ¹⁷ Ωm as dust, the amorphous fluororesin film having a high electrical resistivity of 1 × 10 ¹⁶ Ωm is contaminated and cloudy on the reflective surface. As a result, the reflectance decrease rapidly progressed.

In the same experiment, SiO or SiO ₂ protective film, which has been conventionally used as a transparent protective film and has an electrical resistivity of 1 × 10 ¹² Ωm, is more dirty and cloudy on the reflective surface than the amorphous fluororesin film. Although the reflectivity was small, the antifouling performance was not sufficient.
In other words, the reflective surface of the polygon mirror has the greatest effect of static electricity, and the conventional protective film has a high electrical resistivity. Therefore, it acts as a non-conductor on the static electricity and causes friction with contaminants or air at high speed. As a result, it was possible to estimate that dust around the polygon mirror was adsorbed due to static electricity.

As described above, the conventional protective film has high electrical resistivity (silicon dioxide (SiO ₂ ): 1 × 10 ¹² Ωm, fluororesin: 1 × 10 ¹⁶ Ωm), and acts as a non-electrostatic conductor, around the polygon mirror Of dust is adsorbed. Further, in the fluororesin film having a high electrical resistivity, the reflecting surface is soiled, clouded, and the reflectance is significantly reduced.

Therefore, in the present invention, in view of the above points, the transparent protective film formed on the reflective surface of the polygon mirror has an electric resistivity of 1 × 10 ¹⁰ Ωm or less and is 10 ° or less in terms of a contact angle with water. It is set as the structure which has the hydrophilic property of. Thereby, the transparent protective film works as a static electricity conductor or semiconductor, and it is possible to prevent dust from being adsorbed and contamination of the reflecting surface due to charging.

Further, the polygon mirror of the present invention, the transparent protective film by the conductive fine particles to silicon dioxide (SiO ₂₎ is a transparent protective film which is distributed, silicon dioxide (SiO ₂₎ is of aluminum or an alloy thereof The electrical resistivity can be reduced to 1 × 10 ¹⁰ Ωm or less by dispersing and arranging the conductive fine particles with high adhesion.

Furthermore, in the polygon mirror of the present invention, an oxide-based transparent conductive material such as InO ₃ , SnO ₂ , ZnO or the like has high electrical conductivity (electric resistivity) by using an oxide-based transparent conductive material for the conductive fine particles. 1 × 10 ⁻¹ Ωm or less) and high transparency can prevent the transparent protective film from being charged, and can ensure transparency and prevent a decrease in light quantity.
In the polygon mirror of the present invention, since the carbon nanomaterial is highly conductive by using a carbon nanomaterial for the conductive fine particles, the electrical resistivity is reduced in a small amount, and the transparent protective film is prevented from being charged. Therefore, it is possible to minimize the decrease in the transmittance, ensure the transparency of the protective film, and prevent the light amount from decreasing.

  In the optical deflector according to the present invention, by using the polygon mirror as described above, it is possible to realize an optical deflector with little contamination and fogging of the polygon mirror and a small decrease in reflectance over a long period of time. Further, by imparting hydrophilicity to the transparent protective film of the polygon mirror, it is possible to easily remove the dirt adhering to the reflecting surface, and it is possible to recycle the rotating body including the polygon mirror.

Furthermore, in the optical deflector of the present invention, the main part of the rotating body to which the polygon mirror is fixed is composed of a conductive member made of metal, and the bearing is supported in the radial direction and the fluid dynamic pressure bearing is supported in the axial direction. By configuring the thrust bearing so that the electrical resistivity of the fixed member of the thrust bearing is 1 × 10 ¹⁰ Ωm or less, the static electricity of the transparent protective film generated due to friction with contaminants or air is prevented. Through this, the optical deflector is grounded to the fixed member side of the optical deflector, and the optical deflector can be realized over a long period of time with less contamination and fogging of the polygon mirror and a small decrease in reflectance.

Further, in the optical deflector according to the present invention, the main part of the rotating body to which the polygon mirror is fixed is composed of a conductive member made of metal, and the bearing is supported in the radial direction and the fluid dynamic pressure bearing is supported in the axial direction. And the static resistance of the transparent protective film generated by friction with pollutants or air can be reduced by making the fluid dynamic pressure bearing lubricating oil have an electrical resistivity of 1 × 10 ¹⁰ Ωm or less. The optical deflector is grounded and discharged to the fixing member side of the optical deflector through the lubricating oil, and the optical deflector can be realized over a long period of time with less contamination and fogging of the polygon mirror and a small decrease in reflectance.

  In the optical scanning device of the present invention, by using the optical deflector as described above, the decrease in the reflectance of the polygon mirror is small over a long period of time, and the difference in light utilization efficiency due to the difference in image height position is small. Can be realized.

In the image forming apparatus of the present invention, by using the optical scanning device as described above, fogging and contamination of the polygon mirror surface are prevented, the reflectance of the polygon mirror reflecting surface does not decrease and does not vary, and the image is formed over a long period of time. It is possible to provide a high-quality image forming apparatus in which unevenness in image density due to a difference in high position does not occur.
In the image forming apparatus of the present invention, the toner used for the developing means is a toner in which wax fine particles are dispersed. However, the polygon mirror used in the optical deflector of the optical scanning device has an antistatic property on the reflection surface. Since it has an excellent transparent protective film, even if it is dispersed in the toner and vaporized by heating during fixing and the wax stays in the device, the staying wax adheres to the reflective surface of the polygon mirror. It is possible to prevent the reflectance from partially decreasing, and it is possible to realize a high-quality image forming apparatus that does not cause uneven image density due to the image height position over a long period of time. The paraffin wax dispersed in the toner has a large electric resistivity of 1 × 10 ¹⁴ to 10 ¹⁷ Ωm and is easily charged and adsorbed by friction with a polygon mirror that rotates at high speed. The effect of preventing the charging of the reflecting surface is great, and the contamination of the polygon mirror reflecting surface due to the adsorption of wax and the partial decrease in reflectance can be prevented.

  Further, in the image forming apparatus of the present invention, the toner image visualized on the image carrier is transferred directly to the recording material or via the intermediate transfer member, and the toner image transferred to the recording material is fixed by the heat fixing unit. It is configured to form, but by providing a duct or flow path from the vicinity of the heat fixing unit to the optical deflector, water vapor released from the recording material (for example, recording paper) at the time of heat fixing is recovered, and hydrophilicity is imparted. By continuously supplying appropriate water vapor to the transparent protective film, the antistatic effect is enhanced, and the polygon mirror is prevented from becoming dirty, clouded, and the reflectance is reduced. Therefore, it is possible to realize a high-quality image forming apparatus that does not generate the image.

  Hereinafter, specific examples of the present invention will be described in detail.

[Example 1]
FIG. 1 is a sectional view of an optical deflector using a polygon mirror showing a first embodiment of the present invention.
The optical deflector 100 includes a polygon mirror 101 as a rotating body and a motor below the polygon mirror 101. The polygon mirror 101 includes a bearing shaft 102 that is a rotating shaft, a mirror rotor 105 that is fixed around the bearing shaft 102, and a rotor magnet 106 that is also a part of the motor. The mirror rotor 105 is formed by integrating two reflecting surfaces (polyhedral mirrors) 105a and 105b and a connecting portion 105c. That is, the optical deflector 100 uses the shaft-integrated polygon mirror 101 in which the bearing shaft 102 that is the shaft of the bearing member is shrink-fitted on the polygon mirror 101. The interior of the mirror rotor 105 is cut into a concave shape so that the bearing housing 108 can be easily arranged.

  The rotor magnet 106 is fixed to the lower inner surface of the mirror rotor 105, and constitutes an outer rotor type brushless motor together with a stator core 109 (winding coil 109a) fixed to the bearing housing 108. The bearing housing 108 is fixed to the circuit board 112, and the hall element 113, the driving IC 114, the connector 115, and the like are provided on the circuit board 112.

  The rotor magnet 106 fixed to the lower inner surface of the mirror rotor 105 is preferably a bonded magnet using a resin as a binder, so that the outer diameter portion of the rotor magnet 106 does not break down due to centrifugal force during high-speed rotation. Is held by the holding portion 105g of the mirror rotor 105. The rotor magnet 106 may be fixed to the holding portion 105g with an adhesive. However, the rotor magnet 106 is press-fitted and fixed to the holding portion 105g of the mirror rotor 105 using a material having a linear expansion coefficient substantially equal to that of the mirror rotor 105. It is possible to maintain the rotating body balance with high accuracy without causing a slight movement of the fixed portion even in a higher speed rotation and in a high temperature environment.

The shaft-integrated polygon mirror 101 includes an aluminum alloy as a base material, and upper and lower two-level reflecting surfaces (polyhedral mirrors) 105a and 105b in which a phase difference is provided on the base material by ultra-precision cutting. A transparent protective film is formed on the surfaces 105a and 105b.
The transparent protective film is a conductive transparent protective film in which conductive fine particles are dispersedly disposed in silicon dioxide (SiO ₂ ) and the electrical resistivity is 1 × 10 ¹⁰ Ωm or less. Furthermore, the electrical resistivity of the transparent protective film is desirably 1 × 10 ⁹ Ωm or less.
As the conductive fine particles, an oxide-based transparent conductive material containing an element such as indium (In), tin (Sn), or zinc (Zn) that has high transparency and a low electrical resistivity of 1 × 10 ⁻¹ Ωm or less. Is preferred. As an oxide-based transparent conductive material that can ensure transparency, for example, In ₂ O ₃ , SnO ₂ , ZnO, In ₂ O ₃ doped with Sn (tin) ITO, SnO ₂ doped with Sb (antimony) ATO Etc. are suitable.

Moreover, the transparent protective film of Example 1 has a hydrophilicity of 10 ° or less in terms of a contact angle with water. Furthermore, if it is 7 degrees or less desirably, it does not generate | occur | produce cloudiness on a reflective surface, and is suitable.
Usually, an inorganic material such as glass has a contact angle of 20 to 30 °, a general resin has a contact angle of 70 to 90 °, and a water-repellent silicone or fluororesin has a contact angle of 90 ° to 110 °.

As described above, in the experiments conducted by the present inventors, the amorphous fluororesin film having a contact angle of around 110 ° rapidly deteriorates in the reflection surface, becomes cloudy, and decreases in reflectance. Conventionally used as a transparent protective film, SiO or SiO ₂ film having a contact angle of 20 to 30 ° is less contaminated, cloudy, and has a lower reflectance than the amorphous fluororesin film. The result which is not enough as dirty performance is obtained. For the antifouling performance of the reflective surface of the polygon mirror, a transparent protective film having a hydrophilicity of 10 ° or less in terms of the contact angle with water is required.

The main part of the rotating body to which the polygon mirror 101 is fixed is composed of a conductive member made of metal. The mirror rotor 105 is an aluminum-based metal material, and the bearing shaft 102 is made of martensitic stainless steel (for example, SUS420J2).
An oil-impregnated dynamic pressure bearing is configured as a fluid dynamic pressure bearing that is supported in the radial direction, and a pivot bearing mechanism is provided as the thrust bearing that is supported in the axial direction. Thrust receiving member 110 is made of resin material to improve lubricity, or martensite stainless steel, ceramics, or metal member surface is subjected to hardening treatment such as DLC (diamond-like carbon) treatment to generate wear powder. Is suppressed. The fixed sleeve 107 and the thrust receiving member 110 are housed in the bearing housing 108, and the fluid seal 111 prevents oil from flowing out.

In the configuration of the present invention, the thrust receiving member 110 constituting the pivot bearing mechanism together with the convex curved surface (tip R shape) 102a formed on the lower end surface of the bearing shaft 102 is made of a material having an electrical resistivity of 1 × 10 ¹⁰ Ωm or less. It consists of Furthermore, it is desirable to use a material having a size of 1 × 10 ⁹ Ωm or less.
For example, when a resin material is used for the thrust receiving member 110, the electrical resistivity can be reduced to 1 × 10 ¹⁰ Ωm or less by using a material mixed with a conductive member such as metal or carbon.

By constituting the thrust receiving member 110 with a material having an electrical resistivity of 1 × 10 ¹⁰ Ωm or less, the static electricity generated by friction between the reflective surface of the polygon mirror 101 and contaminants or air can be discharged efficiently, and the reflective surface Adsorption of dirt on 105a and 105b can be prevented. As a discharge path, static electricity charged on the transparent protective film of the reflective surfaces 105a and 105b of the polygon mirror is transferred from the mirror rotor 105 and the bearing shaft 102 to the thrust receiving member 110, the brass bearing housing 108, and the metal-based circuit board 112. Through and discharged to ground.

The lubricating oil of the oil-impregnated dynamic pressure bearing is preferably composed of a lubricating oil having an electrical resistivity of 1 × 10 ¹⁰ Ωm or less. Further, a lubricating oil of 1 × 10 ⁹ Ωm or less is desirable.
The electrical resistivity (Ωm) of conventionally used lubricating oil is as high as mineral oil> 10 ¹⁶ , diester oil 10 ¹³ to 10 ¹⁴ , polyol ester oil 7 × 10 ¹⁴ , polyalkylene glycol oil 1.2 × 10 ^11. Categorized as static non-conductor.
For example, a neutralized salt of an alkylaryl sulfonic acid and an alkylamine as an antistatic agent in an ester base oil disclosed in Patent Document 6 (Japanese Patent Laid-Open No. 2001-115180) is a proportion of 0.1 to 5% by weight. It is preferable to use the lubricating oil contained in

  Static electricity charged on the transparent protective film of the reflecting surface 105a of the mirror rotor 105 of the polygon mirror 101 is efficiently transferred from the mirror rotor 105 and the bearing shaft 102 to the main body through the fixed sleeve 107, the bearing housing 108, and the circuit board 112. It discharges well.

In the present invention, the electrical resistivity of either the thrust receiving member 110 or the lubricating oil may be 1 × 10 ¹⁰ Ωm or less, or both electrical resistivity may be 1 × 10 ¹⁰ Ωm or less.

  In the shaft-integrated polygon mirror 101, a bearing shaft 102 having a diameter of 2 to 3 mm is fixed to a hole formed in the mirror rotor 105 by shrink fitting. Since the shrink-fitting hole is formed to be several μm to 10 μm smaller than the shaft diameter, the mirror rotor 105 is heated to 200 to 300 ° C. so that the bearing shaft 102 can be inserted with a margin. Make a shrink fit. The shrinkage allowance when cooled to room temperature is about 3 to 10 μm, and when reheated to about 120 ° C to 160 ° C, the shrinkage allowance becomes zero, and the shaft and the hole are loosely fixed. It will end up.

  In the shaft-integrated polygon mirror 101, after the bearing shaft 102 is fixed to the mirror rotor 105 by shrink fitting, the reflecting surfaces 105a and 105b are arranged so that the inclination (surface tilt) of the reflecting surfaces 105a and 105b with respect to the rotation axis becomes uniform. Forming. If the bearing shaft 102 is loosened, the surface tilt becomes large and the optical characteristics cannot be satisfied. Therefore, as in the above-mentioned Patent Document 2, the film is formed by a wet film forming method in which heating is performed at 170 to 180 ° C. I can't.

The transparent protective film in which conductive fine particles are dispersedly disposed in silicon dioxide (SiO ₂ ) can be coated by a wet film forming method such as spray coating, spin coating, dip coating or the like.
Specifically, the protective film can be formed with a film thickness of about 0.1 to 0.2 μm by applying methanol, ethanol or the like to the reflective surface and volatilizing the solvent. Although the transparent protective film can be cured at room temperature, the curing time can be shortened by heating to about 80 ° C. within a range where the shrink-fitted portion does not loosen.
Further, in the case of a single polygon mirror that does not have a shaft-integrated structure, this is not a limitation, and heating may be performed at a high temperature.

In Example 1 of the present invention, by lowering the electrical resistivity of the transparent protective film to 1 × 10 ¹⁰ Ωm or less, it works as an electrostatic conductor or semiconductor, preventing and reducing contamination of the reflecting surface due to charging and dust adsorption. can do.
A transparent protective film having excellent antistatic properties can prevent contamination of the reflecting surfaces 105a and 105b of the polygon mirror 101 and partial reduction in reflectance due to adsorption of surrounding dust.
Further, by imparting hydrophilicity of 10 ° or less in terms of contact angle with water to the transparent protective film, water molecules in the air are adsorbed to increase the durability of the antistatic effect, and for a long period, the polygon mirror 101 There is little dirt and fogging, and the decrease in reflectance is small.
Furthermore, the polygon mirror 101 in which a hydrophilic transparent protective film is formed of an inorganic material has no deterioration of the transparent protective film due to aging, and dirt after aging can be easily removed by washing with water. The mirror 101 can be recycled.

In Example 1 of the present invention, carbon nanomaterials may be dispersed and arranged as the conductive fine particles of the transparent protective film.
Furthermore, a mixture of an oxide-based conductive material and a carbon nanomaterial may be dispersed as conductive fine particles.
Examples of the carbon nanomaterial include carbon nanotubes (hereinafter referred to as CNT), fullerenes such as C60 and C70, carbon nanohorns, and carbon nanocapsules.
Carbon nanomaterials such as CNT and fullerene are disclosed in, for example, Patent Document 7 (Japanese Patent Publication No. 2006-509703), Patent Document 8 (Japanese Patent Laid-Open No. 2001-104771), Patent Document 9 (WO 2007/083681), and the like. By solubilizing in a hydrophilic solvent such as water or alcohol by a method such as chemical modification or physical adsorption, applying to the reflective surface using water, methanol, ethanol or the like as a solvent, and evaporating the solvent, 0.1 A transparent protective film can be formed with a film thickness of about 0.2 μm.
Since the carbon nanomaterial has very high conductivity, the electrical resistivity can be lowered in a very small amount, the transparency of the transparent protective film can be ensured, and the reduction of the light amount can be prevented.

[Example 2]
Next, FIG. 2 is an explanatory view of the configuration of an optical scanning device showing a second embodiment of the present invention.
2A and 2B, a light beam (laser beam) L emitted from a laser generator 201 as a light source is reflected by a polygon mirror 202 of an optical deflector and passes through an imaging lens group 203. An image is formed on the photosensitive drum 204. At this time, the polygon mirror 202 is rotated by the motor 205, and a part of the laser beam L is guided to the detector 207 by the reflection mirror 206, and the writing timing of each laser beam L is detected.
The motor 205 of the optical deflector includes a rotor 208, a rotating shaft 209, a motor board 210, a housing 211, and the like, and a driving IC 212 is disposed on the motor board 210. In the example of FIG. 2, the polygon mirror 202 is fixed to the rotor 208 by a presser spring 213, but may be a shaft-integrated polygon mirror as in the configuration of the first embodiment (FIG. 1).

The motor 205 is accommodated in the optical box 214, and a cover 215 is fixed to the optical box 214 by a claw 215a so that dust or the like outside the optical box 214 does not enter the inside.
Above the polygon mirror 202, a substantially cylindrical outside air induction rectifying member 220 is provided in close proximity. The outside air induction rectifying member 220 has an outside air inlet side fixed to the cover 215 and another end arranged close to the polygon mirror 202. The surface where the outside air rectifying member 220 faces the polygon mirror 202 is formed as a substantially ring-shaped plane.

As shown in the perspective view of FIG. 3, the outside diameter D1 of the outside air rectifying member 220 is formed to be larger than the inscribed circle diameter D2 formed on each reflecting surface of the polygon mirror 202. The outside air induction rectifying member 220 is provided with a filter 221.
The filter 221 is attached so as to be replaceable using a double-sided tape, a screw or the like. In order to facilitate replacement, the filter 221 may be elastically fixed using a spring member or the like.

  In FIG. 2B, the flow of air generated when the polygon mirror 202 rotates is schematically indicated by arrows. As the polygon mirror 202 rotates, air flows from above and below the polygon mirror 202 so as to supplement the air pushed out by the reflecting surface of the polygon mirror 202. Then, negative pressure is sequentially transmitted from above the polygon mirror 202 to the inside of the outside air rectifying member 220 that is the outside air guiding channel, and outside air is guided to the inside of the optical box 214. At this time, the outside air passes through the filter 221, so that contaminants are adsorbed, and purified air is supplied around the polygon mirror 202.

  The outside air induction rectifying member 220 prevents a circulation flow around the polygon mirror 202, supplies purified air around the polygon mirror 202, forms an air curtain by the air flow, and reflects the polygon mirror 202. Prevent cloudiness and contamination. In order to enhance the outside air guiding effect and prevent the circulation flow around the polygon mirror 202, the outside diameter D1 of the outside air rectifying member 220 is equal to the inscribed circle diameter D2 formed on each reflecting surface of the polygon mirror 202. Or larger than that. It is more preferable to make the outer diameter D1 larger than the circumscribed circle diameter D3 formed by the vertexes of the polygon mirror (hexagonal apex in the case of 6 faces).

  Further, the gap G with the end face of the outside air induction rectifying member 220 provided close to the polygon mirror 202 is preferably 3 to 5 mm or less. As the gap G is reduced, the effect of inducing outside air increases, but an appropriate gap G is set within a range of about 1 to 5 mm so that noise is not generated by the airflow caused by the rotation of the polygon mirror 202.

  The optical box 214 is not provided with an exhaust port in particular, but is not completely sealed. Therefore, when the pressure in the optical box increases due to the induction of outside air, the joint between the optical box 214 and the cover 215 is formed. Air flows out of the gap. At this time, the air in the optical box heated by the heat generated by the rotation of the polygon mirror 202 due to the rotation of the motor part and the bearing part and the frictional heat with the air of the polygon mirror itself is pushed to the outside. Guided around the polygon mirror 2. As a result, the cooling effect of the optical deflector (polygon scanner), which is a heat generation source, is enhanced, and the amount of heat transferred to the optical components such as the imaging lens group 203 arranged in the optical box is reduced. And the temperature deviation in an optical component becomes small.

The polygon mirror 202 used in the optical scanning device of the second embodiment has an electrical resistivity as small as 1 × 10 ¹⁰ Ωm or less on the reflecting surface as in the first embodiment, and is 10 ° or less in terms of a contact angle with water. A transparent protective film having hydrophilicity is formed.

With the above configuration, operation, and action, the temperature rise around the polygon mirror is suppressed, the temperature distribution (temperature difference) in the optical box 214 is reduced, and the surface of the photoconductor 204 that is the surface to be scanned is reduced. The displacement of the imaging position of the light beam and the image deterioration are reduced. In addition, by guiding the outside air from which contaminants have been removed by the filter 221 and always supplying purified air around the polygon mirror 202, the reflection surface of the polygon mirror 202 can be prevented from being clouded or contaminated. . Even if there are contaminants that could not be removed by the filter 221, a transparent protective film having a high hydrophilicity and a low electrical resistivity of 1 × 10 ¹⁰ Ωm or less is formed on the reflective surface of the polygon mirror 202. Therefore, the reflective surface will not be dirty or cloudy. Since the polygon mirror 202 of the second embodiment is excellent in the antifouling performance of the reflecting surface, it is not necessary to use a filter having a high dust collection effect, and a filter with a small pressure loss can be used as a filter characteristic. The cooling effect by induction can be enhanced.

[Example 3]
Next, FIG. 4 is a schematic sectional view of an optical scanning device showing a third embodiment of the present invention.
An optical deflector (polygon scanner) 140 in which a two-stage polygon mirror 140a is formed is housed in a core casing 700 in an optical box, and a cover 711 is fixed to a sub casing 710 to which the core casing 700 is attached. Thus, dust or the like outside the optical box is prevented from entering the inside.
In the optical box composed of the sub-housing 710 and the cover 711 shown in FIG. 4, an imaging lens group composed of a plurality of scanning lenses, a reflection mirror, and the like are arranged as in FIG. However, these illustrations are omitted.
The configuration of the optical deflector (polygon scanner) 140 is substantially the same as that of the optical deflector of the first embodiment (FIG. 1), but the shape of the polygon mirror is different.

  Above the polygon scanner 140, an outdoor air induction rectifying member 130 is provided in close proximity. The outside air induction rectifying member 130 has an outside air inlet side fixed to the cover 711, and another end is arranged close to the polygon mirror 140 a. The surface where the outside air induction rectifying member 130 faces the polygon mirror 140a is formed as a substantially ring-shaped plane. The inside of the outside air induction rectifying member 130 serving as an outside air guiding channel is formed in a substantially conical shape that extends from the outside air side toward the polygon mirror 140a. As shown in FIG. 5, the outside diameter D3 of the outside air induction rectifying member 130 from the outside side is formed with a diameter larger than the circumscribed circle diameter D4 formed at the apex of the polygon mirror 140a (hexagonal apex in the case of 6 faces). Has been. Further, the outside air induction rectifying member 130 is provided with a filter 131.

FIG. 6 shows an enlarged view of the filter 131. The filter 131 has a structure in which an activated carbon filter 131c is sandwiched between sheet-like electrostatic filters 131a and 131b. 131d is a structural material that holds the activated carbon filter 131c together with the sheet-like electrostatic filters 131a and 131b.
The activated carbon filter 131c is, for example, an activated carbon sheet that works as an adsorbent, such as Tomibo's Chemifi (registered trademark) series, or an electret filter that removes dust and an activated carbon sheet that removes gaseous chemical substances. A combination of these can be used.

When the polygon mirror 140a is small and the generated air volume is small, as shown in FIG. 7, as the filter 131, when activated carbon paper is processed into a honeycomb shape by a single-stage cardboard lamination method, the pressure loss of the filter is reduced. Small and suitable.
The filter 131 is attached to the outside air induction rectifying member 130 in a replaceable manner using a double-sided tape, a screw, or the like. In order to facilitate replacement, the filter 131 may be elastically fixed using a spring member or the like.

  FIG. 4 schematically shows the flow of air generated when the polygon mirror 140a rotates by arrows. As the polygon mirror 140a rotates, air flows from above and below the polygon mirror 140a so as to supplement the air pushed out by the reflecting surface of the polygon mirror 140a. Negative pressure is transmitted in the order above the polygon mirror 140a and inside the outside air guiding and rectifying member 130, and outside air is guided inside the sub-housing 710 that is an optical box. At this time, the outside air passes through the sheet-like electrostatic filters 131a and 131b and the activated carbon filter 131c, so that dust and gaseous contaminants are adsorbed, and purified air is supplied around the polygon mirror 140a. The Since the outside diameter D5 of the outside air rectifying member 130 is formed with a diameter larger than the circumscribed circle diameter D4 formed at the apex of the polygon mirror 140a, the circulation flow around the polygon mirror 140a is prevented, and the polygon mirror 140a. A clean air is always supplied to the periphery of the lens, and an air curtain is formed by an air flow, and the reflection surface of the polygon mirror 140a is prevented from being clouded or contaminated. Moreover, if the outside diameter D5 of the outside air induction rectifying member 130 is formed larger than the inscribed circle diameter (corresponding to D2 in FIG. 3) formed by each reflecting surface of the polygon mirror 140a, the reflecting surface of the polygon mirror 140a. The effect of preventing fogging and contamination can be obtained, but a greater effect can be obtained by forming the polygon mirror 140a with a diameter larger than the circumscribed circle diameter D4.

  The gap G with the end face of the outside air rectifying member 130 provided in the vicinity of the polygon mirror 140a is preferably 3 to 5 mm or less. As the gap G is reduced, the effect of inducing outside air increases. However, an appropriate gap G is set within a range of about 1 to 5 mm so that noise is not generated by the airflow generated by the rotation of the polygon mirror 140a.

  The sub casing 710, which is an optical box, is not provided with a special exhaust port, but is not completely sealed. Therefore, when the pressure inside the sub casing 710 increases, the sub casing 710 and the cover are covered. Air flows out from the gap of the joint 711 to the outside. At this time, the heat in the motor box and the bearing portion accompanying the rotation of the polygon mirror 140a, the air in the optical box heated by the frictional heat with the air of the polygon mirror 140a itself is pushed out, and the outside air having a relatively low temperature Is guided around the polygon mirror 140a. As a result, the cooling effect of the polygon scanner 140, which is a heat generation source, is enhanced, and the amount of heat transferred to the optical components such as the imaging lens group disposed in the optical box is reduced. Temperature deviation is reduced.

The polygon mirror 140a used in the optical scanning device of the third embodiment has an electrical resistivity as small as 1 × 10 ¹⁰ Ωm or less on the reflecting surface as in the first embodiment, and is 10 ° or less in terms of a contact angle with water. A transparent protective film having hydrophilicity is formed.

With the above configuration, operation, and action, the temperature rise around the polygon mirror 140a is suppressed, the temperature distribution in the optical box (temperature difference) is reduced, and the surface of the photoconductor as the scanned surface is reduced. The displacement of the imaging position of the light beam and the image deterioration are reduced. In addition, outside air from which dust and gaseous contaminants have been removed is guided by the filter 131 (electrostatic filters 131a and 131b and activated carbon filter 131c) of the outside air rectifying member 130, and is always cleaned around the polygon mirror 140a. By supplying air, the reflection surface of the polygon mirror 140a can be prevented from being clouded or contaminated. Further, even if there is a contaminant that could not be removed by the filter 131, a transparent protective film having a small electrical resistivity of 1 × 10 ¹⁰ Ωm or less and high hydrophilicity is formed on the reflective surface of the polygon mirror 140a. Therefore, the reflecting surface is not soiled or clouded. Since the polygon mirror 140a of Example 3 is excellent in the antifouling performance of the reflecting surface, it is possible to use the filter 131 having a small pressure loss as a filter characteristic, and the cooling effect by the outside air induction can be enhanced.

[Example 4]
Next, as a fourth embodiment, an embodiment of an image forming apparatus incorporating a polygon mirror according to the present invention and an optical scanning device using the polygon mirror will be described with reference to FIG.
FIG. 8 is a schematic configuration diagram showing an example of an image forming apparatus using the optical scanning device described so far. The image forming apparatus shown in FIG. 8 is an example of a tandem color image forming apparatus in which a plurality of image carriers (photosensitive members) 53Y, 53M, 53C, and 53K are arranged in parallel. In this image forming apparatus, the optical scanning device 50, developing devices 56Y, 56M, 56C, and 56K as developing means, drum-shaped photoconductors 53Y, 53M, 53C, and 53K made of a photosensitive medium, and intermediate transfer are sequentially arranged from the top in the device. The intermediate transfer belt 52, the fixing device 57, and the paper feed cassette 51, which are the body, are laid out. Above the intermediate transfer belt 52 spanned between the pair of rollers 52a and 52b and the other roller 52c so that the upper surface is horizontal, the photoreceptors 53Y, 53M, 53C, and 53K corresponding to the respective colors. The belts 52 are arranged in order along the moving direction of the belt 52, and are arranged at equal intervals close to the upper surface of the belt 52. The photoconductors 53Y, 53M, 53C, and 53K are formed to have the same diameter, and process devices for sequentially executing the electrophotographic processes are sequentially arranged around the photoconductors in the rotation direction of each photoconductor. The photosensitive member 53Y will be described as an example. A charging charger (not shown), an exposure unit scanned with a laser beam L1 based on an image signal emitted from the optical scanning device 50, a developing device 56Y, and a transfer charger (not shown). A cleaning device (not shown) and the like are sequentially arranged. The same applies to the other photoconductors 53M, 53C, and 53K.
In the embodiment of the image forming apparatus shown in FIG. 8, the photoconductors 53Y, 53M, 53C, and 53K are to be scanned surfaces set for respective colors, and laser beams L1, L2, and L3 emitted from the optical scanning device 50 are used. , L4 are provided so as to scan the surface of each photoreceptor corresponding to each.

  The image forming process and color image forming process in each of the photoreceptors 53Y, 53M, 53C, and 53K are as follows. First, the image forming process in the yellow (Y) photoreceptor 53Y will be described as a representative of each photoreceptor. The photoconductor 53Y uniformly charged by a charging charger (not shown) is subjected to main scanning by scanning with the laser beam L1 from the optical scanning device 50, and sub-scanning is performed by rotating the photoconductor 53Y in the arrow direction. The electrostatic latent image is formed on the photoreceptor 53Y. Further, a developing device 56Y that supplies toner to the photoconductor 53Y is disposed downstream of the irradiation position of the laser beam L1 by the optical scanning device 50 in the rotation direction of the photoconductor 53Y, and yellow (Y) toner is supplied. Is done. The toner supplied from the developing device 56Y adheres to the portion where the electrostatic latent image is formed, and a toner image is formed. Similarly, magenta (M), cyan (C), and black (K) monochromatic toner images are formed on the other photoconductors 53M, 53C, and 53K, respectively.

  The upper surface of the intermediate transfer belt 52 is located further downstream of the photoconductors 53Y, 53M, 53C, and 53K in the rotation direction than the arrangement positions of the developing devices 56Y, 56M, 56C, and 56K of the photoconductors 53Y, 53M, 53C, and 53K. Is located. The intermediate transfer belt 52 is wound around a plurality of rollers 52a, 52b, and 52c, and is moved in the arrow B direction by driving a motor (not shown). The intermediate transfer belt 52 moves in the order of the photoconductors 53Y, 53M, 53C, and 53K, and transfers the single-color images developed on the photoconductors 53Y, 53M, 53C, and 53K in sequence by a primary transfer unit (not shown). In addition, a color image is formed on the intermediate transfer belt 52. Thereafter, the recording paper as the recording material is conveyed from the paper feed tray 51 in the direction of arrow C, and the color image on the intermediate transfer belt 52 is transferred to the recording paper. The recording paper on which the color image is formed is fixed by a fixing device 57 that is a heat fixing unit, and then discharged onto a paper discharge tray at the top of the device. Further, the residual toner on each of the photosensitive members 53Y, 53M, 53C, 53K and the intermediate transfer belt 52 after the image is transferred is removed by a cleaning device (not shown).

In the toner used in each of the developing devices 56Y, 56M, 56C, and 56K of the image forming apparatus, wax fine particles having a high electrical resistivity of 1 × 10 ¹⁴ to 10 ¹⁷ Ωm are dispersed.
In view of this, the image forming apparatus shown in FIG. 8 is provided with a duct 58 connected from the vicinity of the fixing device 57 to the optical deflector (polygon scanner) 50a in the optical scanning device 50, and is included in the recording paper and discharged during fixing. A part of the water is collected, and the air current flows in the direction of the arrow in the duct 58 to supply it to the optical deflector 50a. In FIG. 8, details of the optical scanning device such as a dustproof filter, an outside air induction rectifying member, an imaging lens group composed of a plurality of scanning lenses, and a reflection mirror are omitted, and only the polygon mirror portion of the optical deflector 50a is illustrated. Although shown, the air flow in the duct 58 may be the air flow generated by the rotation of the polygon mirror as in the third embodiment, or a separate fan may be provided. As shown in FIG. 8, if the fixing device 57 is disposed below the optical scanning device 50, airflow may be induced to the optical deflector using natural convection due to heat during fixing. . The duct 58 in FIG. 8 is configured to be completely connected from the vicinity of the fixing device 57 to the optical deflector 50a in the optical scanning device 50. However, as shown in FIG. By controlling the airflow, the duct 59 may be provided only in a part near the optical scanning device.

  In FIGS. 8 and 9 of the fourth embodiment, the optical scanning device 50 using the optical deflector 50a composed of a two-stage polygon mirror is illustrated. However, as in the second embodiment, a single-stage polygon is used. An optical scanning device including a mirror can also be applied to the image forming apparatus according to the present invention. Further, the image forming apparatus according to the present application is configured by using the optical scanning device configured by the polygon mirror 101 having the two-stage reflecting surfaces 105a and 105b provided with the upper and lower phase differences as shown in the first embodiment. The present invention is also possible, and can be applied to all optical scanning devices and image forming devices configured using a polygon mirror.

According to the image forming apparatus of the present invention, the temperature rise around the polygon mirror is suppressed, the temperature distribution (temperature difference) in the optical box is reduced, and the light beam imaging position on the photoconductor Deviation and image degradation are reduced. Moreover, the air curtain is formed by the air flow cleaned by the filter, so that the reflection surface of the polygon mirror can be prevented from being clouded or contaminated. Even if there are contaminants that could not be removed by the filter, the polygon mirror's reflective surface has a transparent protective film with a low electrical resistivity of 1 × 10 ¹⁰ Ωm or less and high hydrophilicity. The reflective surface of the mirror will not become dirty or cloudy. Therefore, it is possible to provide an image forming apparatus that can obtain a high-quality image without deterioration and no variation in the reflectance of the polygon mirror reflecting surface and without image deterioration.

According to the image forming apparatus of the present invention, even a toner in which wax particles having a high electrical resistivity of 1 × 10 ¹⁴ to 10 ¹⁷ Ωm are dispersed is vaporized by the fixing device and is contained in the apparatus. It is possible to prevent the wax-dispersed fine particles in the staying toner from being adsorbed and fixed to the reflection surface of the polygon mirror by electrostatic force.
Also, some of the moisture contained in the recording paper and released during fixing is collected and supplied to the optical deflector, so that the surface of the transparent protective film of the polygon mirror having hydrophilicity is always covered with water molecules, The antistatic function can be maintained and contamination of the reflecting surface can be prevented.

50: Optical scanning device 50a: Optical deflector (polygon scanner)
51: Paper feed cassette 52: Intermediate transfer belt (intermediate transfer member)
53Y, 53M, 53C, 53K: photoconductor (image carrier (scanned surface))
56Y, 56M, 56C, 56K: Development device 57: Fixing device (heat fixing unit)
58, 59: Duct 100: Optical deflector (polygon scanner)
101: Shaft-integrated polygon mirror 102: Bearing shaft 105: Mirror rotor 105a, 105b: Reflecting surface (polyhedral mirror)
106: Rotor magnet 107: Fixed sleeve 108: Bearing housing 109: Stator core 109a: Winding coil 110: Thrust receiving member 111: Fluid seal 112: Circuit board 113: Hall element 114: Drive IC
115: Connector 130: Outside air induction rectifying member 131: Filter 131a, 131b: Electrostatic filter 131c: Activated carbon filter 140: Optical deflector (polygon scanner)
140a: Polygon mirror 201: Laser generator (light source)
202: Polygon mirror 203: Imaging lens group 204: Photosensitive drum (image carrier (scanned surface))
205: motor 206: reflection mirror 207: detector 208: rotor 209: rotating shaft 210: motor substrate 211: housing 212: driving IC
213: Presser spring 214: Optical box 215: Cover 220: Outside air induction rectifying member 221: Filter 700: Core casing 710: Sub casing (optical box)
711: Cover

JP 2004-125890 A JP 2002-131682 A JP 2008-33135 A Japanese Unexamined Patent Publication No. 1-196018 Japanese Patent No. 3192271 JP 2001-115180 A JP-T-2006-509703 JP 2001-104771 A WO 2007/083681

Claims (11)

In a polygon mirror in which a plurality of reflective surfaces that reflect light from a light source are formed by cutting on a base material made of aluminum or an alloy containing aluminum, and the transparent protective film is formed on the reflective surface,
The transparent protective film has a resistivity of 1 × 10 ¹⁰ Ωm or less, and has a hydrophilicity of 10 ° or less in terms of a contact angle with water. The polygon mirror according to claim 1,
The polygon mirror according to claim 1, wherein the transparent protective film is a transparent protective film in which conductive fine particles are dispersedly disposed in silicon dioxide (SiO ₂ ). The polygon mirror according to claim 2,
The polygonal mirror characterized in that the conductive fine particles are an oxide-based transparent conductive material. The polygon mirror according to claim 2,
The polygon mirror characterized in that the conductive fine particles are a carbon nanomaterial. In an optical deflector in which a rotating body to which a polygon mirror is fixed is supported by a bearing,
The optical deflector according to claim 1, wherein the polygon mirror is the polygon mirror according to claim 1. The optical deflector according to claim 5, wherein
The main part of the rotating body to which the polygon mirror is fixed is composed of a conductive member made of metal,
The bearing comprises a fluid dynamic pressure bearing that supports in the radial direction and a thrust bearing that supports in the axial direction,
An optical deflector characterized in that an electrical resistivity of a fixed side member of the thrust bearing is 1 × 10 ¹⁰ Ωm or less. The optical deflector according to claim 5, wherein
The main part of the rotating body to which the polygon mirror is fixed is composed of a conductive member made of metal,
The bearing comprises a fluid dynamic pressure bearing that supports in the radial direction and a thrust bearing that supports in the axial direction,
An optical deflector characterized in that an electrical resistivity of lubricating oil of the fluid dynamic pressure bearing is 1 × 10 ¹⁰ Ωm or less. A light beam from a light source is guided to a scanned surface through an optical system including a light deflector to form a light spot on the scanned surface, and the light beam is deflected by the light deflector. In an optical scanning device that scans a scanning line with a scanning line by the light spot on a surface to be scanned,
An optical scanning device, wherein the optical deflector is the optical deflector according to claim 5. In an image forming apparatus for forming a latent image by performing optical scanning with an optical scanning device on a photosensitive surface of an image carrier made of a photosensitive medium, and obtaining the image by visualizing the latent image with toner of a developing unit.
An image forming apparatus using the optical scanning device according to claim 8 as an optical scanning device for optically scanning the photosensitive surface of the image carrier. The image forming apparatus according to claim 9.
An image forming apparatus, wherein the toner used in the developing unit is a toner in which wax fine particles are dispersed. The image forming apparatus according to claim 9 or 10, wherein:
The toner image visualized on the image carrier is transferred to a recording material directly or via an intermediate transfer member, and the toner image transferred to the recording material is fixed by a heat fixing unit to form an image.
An image forming apparatus comprising a duct or a flow path connecting from the vicinity of the heat fixing unit to the optical deflector.

Images