JP6595178B2 - Polygon mirror, scanner unit, and image forming apparatus - Google Patents

Description

  The present invention relates to a polygon mirror used in an optical scanning device such as a laser beam printer, a scanner unit including the polygon mirror, and an image forming apparatus including the scanner unit.

  Conventionally, an optical scanning device such as a laser beam printer is equipped with a scanner unit that scans a laser beam with a polygon mirror that is a rotating polygon mirror (see Patent Document 1).

JP 2005-172930 A

  In the conventional polygon mirror described above, for example, the reflectance may change depending on the incident angle of the laser beam, and it is difficult to realize high-precision optical scanning.

  The present invention provides a polygon mirror, a scanner unit, and an image forming apparatus that can cope with a wide range of incident angles.

The polygon mirror of the present invention comprises a light reflecting surface formed by laminating a plurality of resin layers,
Only the outermost resin layer forming the plurality of light reflecting surfaces is an amorphous fluororesin layer,
The resin layer that is the base of the amorphous fluororesin layer is a fluorene resin layer.
In such an aspect of the present invention, the amount of amorphous fluororesin used can be reduced by using the fluorene resin layer as a base, and a polygon mirror corresponding to a wide incident angle range can be realized at low cost.

The present invention is also widely applied to the scanner unit including the polygon mirror described above or an image forming apparatus including the scanner unit.
According to such an aspect of the present invention, it is possible to realize a scanner unit and an image forming apparatus that can realize small and highly accurate optical scanning.

  According to the present invention, it is possible to realize a polygon mirror, a scanner unit, and an image forming apparatus that can cope with a wide incident angle range.

Schematic which shows the principal part structural example of an optical scanning device. The figure explaining the rotary wet film-forming method. The schematic diagram showing the liquid pool of the reflective surface by the rotating wet film-forming method. The schematic diagram showing the reflective surface which formed the two-layer optical film concerning this invention by reverse rotation. FIG. 3 is a comparison diagram of Examples 1 and 2 and Comparative Examples 1 and 2 according to the present invention.

Hereinafter, the present invention will be described in detail based on embodiments.
The present invention is a polygon mirror that reflects light, and includes a light reflecting surface formed by laminating a plurality of resin layers. Such a polygon mirror has a light reflection surface formed by laminating a plurality of resin layers, so that the film thickness distribution can be suppressed and a wide incident angle range can be handled.

  Here, in the polygon mirror of the present invention, the laminated interfaces in the plurality of resin layers are inclined with respect to the light reflecting surface. This is because each of the plurality of resin layers forms an inclined surface inclined with respect to the base surface of the main body of the polygon mirror, and this is alternately combined to average the film thickness distribution of each resin film and It becomes possible to form a simple light reflecting surface.

  For example, a polygon mirror forms a resin layer on each surface while rotating a polygonal rotating body having a rotation center. At this time, the resin layer is formed to be inclined in the rotation direction. However, by rotating the rotation direction in the reverse direction and stacking a plurality of resin layers, the resin layer is formed on the lower ground of the rotating body as a result. The reflecting surface is a substantially parallel surface. At this time, the laminated interface of the plurality of resin layers is an inclined surface.

  In the polygon mirror of the present invention, it is preferable that only the outermost resin layer forming the plurality of light reflecting surfaces is an amorphous fluororesin layer. Thereby, since the usage-amount of a comparatively expensive amorphous fluororesin can be reduced, the polygon mirror corresponding to a wide incident angle range is realizable at low cost.

  In the polygon mirror of the present invention, it is preferable that the resin layer serving as the base of the amorphous fluororesin layer is a fluorene resin layer. By using the fluorene resin layer as a base, it is excellent in durability and the amount of amorphous fluororesin used can be reduced, and a polygon mirror corresponding to a wide incident angle range can be realized at low cost.

  The present invention can be applied to a scanner unit including the polygon mirror described above, or an image forming apparatus including the scanner unit, more specifically, a laser beam printer. Since the polygon mirror of the present invention can cope with a wide incident angle range, it is advantageous for miniaturization and can realize high-precision optical scanning.

  Hereinafter, embodiments of the present invention will be specifically described.

  In one embodiment of the present invention, for example, in a reflective polygon mirror mounted on an optical scanning device used in an electrophotographic apparatus or the like, the polygon mirror is a polygon mirror in which the light reflecting surface of the polygon mirror is formed by two layers of optical films. The polygon mirror of this embodiment is mounted as a rotating polygon mirror on an optical scanning device such as a laser beam printer. Specifically, the image carrier surface is optically scanned with a light-modulated light beam through a polygon mirror, and image information is written and read out. Here, FIG. 1 shows a schematic diagram of an optical scanning device. In FIG. 1, a light beam emitted from a light source unit 1 such as a semiconductor laser is converted into a parallel light beam by a collimator lens 2 and condensed by a cylindrical lens 83 having a refractive power only in the sub-scanning direction. The light is incident linearly on the deflecting / reflecting surface 4a. The collimator lens 2 and the cylindrical lens 83 constitute an imaging optical system. The light beam reflected and deflected by the deflecting / reflecting surface 4 a is guided onto the scanned surface 89 by the lens 87 b having a negative refractive power made up of a spherical surface constituting the scanning lens 87 to form a spot. Then, the deflector 4 is rotated in the direction of the arrow 86 by the motor 85 about the rotation shaft 82 to optically scan the deflection scanning surface on the surface to be scanned 89 in the direction of the arrow 90 (main scanning direction).

  The reflective polygon mirror of this embodiment mounted on such an optical scanning device can suppress variations in the thickness of the reflective surface by forming the light reflective surface with two optical films. The dependence of the reflectance on the incident angle / position of incident light can be suppressed. This eliminates the need for strict control during film formation. For the two-layer optical film, it is preferable to use a wet film formation method that can be suppressed at low cost.

  Here, the wet film forming method is a method in which a solution containing a desired film quality or a film quality precursor is applied to a substrate, and a solvent is removed from the solution or the precursor is reacted to form a desired film on the substrate. Alternatively, a desired film is formed by a reaction between a substrate and a substance in the solution in the solution.

  As the wet film forming method, for example, a solution wet film forming method typified by dip coating or spin coating, and particularly when the polygon mirror substrate is aluminum, an aluminum oxide film may be formed by using an anodic oxidation method. Although possible, it is desirable to use a solution wet film-forming method with particularly low equipment costs.

  The solution wet film forming method is a method in which a solution obtained by dissolving a substance that forms a film in a solvent is applied to a surface on which a film is to be formed, and dried or baked to obtain a film. The dip coating and spin coating described above are suitable for forming one surface or two parallel surfaces, but for film formation of a polyhedron seen in a polygon mirror, a rotating film forming method in which a reflecting surface is taken in the radial direction of rotation. Is most desirable. The meaning of taking the reflecting surface in the radial direction of rotation is that the normal line of the reflecting surface coincides with the rotating radial direction.

  The rotary wet film-forming method has a coating process for coating a coating liquid on the reflecting surface of a polygon mirror, and subsequently a film thickness control process for rotating the polygon mirror while controlling the number of rotations to obtain a desired film thickness. . There is also a baking step in which the solvent contained in the coating solution is removed to dry and fix the film. FIG. 2 shows a schematic diagram of a coating process in which the polygon mirror 4b is rotated while being in contact with the coating solution 5 to form a surface layer having a predetermined film thickness.

  In a polygon mirror in which a two-layer optical film is formed on a substrate, the first layer and the outermost layer are formed in order to form a uniform film in which the end of the reflecting surface does not accumulate a solution after rotation film formation with high productivity. It is most desirable that the coating direction is reverse rotation. By forming a film with this method, the variation in film thickness is reduced, and a high-quality film can be stably obtained. Therefore, the manufacturing defect loss is reduced, and the polygon mirror is manufactured with good productivity and at a low cost. Is possible. For example, after forming the coating film 5a on the surface layer of the polygon mirror 4b as shown in FIG. 3, the polygon mirror 4b is rotated in the reverse direction to form the coating film 5b on the coating film 5a as shown in FIG. . At this time, a laminated interface 5c inclined with respect to the light reflecting surface 4a is formed at the interface between the coating film 5a and the coating film 5b. Thereby, the light reflection surface 4a becomes a surface substantially parallel to the surface of the polygon mirror 4a main body.

  Here, if the film thickness does not cause multiple reflection in the film, the reflectance tends to decrease as the film thickness increases in the incident angle range narrower than the Brewster angle. On the other hand, in the incident angle range wider than the Brewster angle, the reflectance tends to increase as the film thickness increases.

  In other words, since the film thickness at which the reflectivity of the Brewster angle can be obtained is theoretically obtained for each incident angle, forming the film thickness faithfully on the reflection surface suppresses the angle dependency of the reflectivity. It is particularly desirable from the viewpoint of.

  For example, when the incident angle of p-polarized light is limited to a range narrower than the Brewster angle, it is easy to achieve uniform reflectance with a uniform film thickness. At this time, the reflectance rapidly increases on the wide angle side from the Brewster angle. Therefore, an ideal film shape can be approximated by forming films having different refractive indexes by the above-described method.

  Here, the base material on which the two-layer optical film is formed is not particularly limited by the present invention as long as it can be used for a polygon mirror, such as aluminum, plastic, and glass.

  In addition, the film material to be deposited on the reflective surface of the polygon mirror can be appropriately determined in consideration of the durability under the use conditions. For example, thermosetting resins such as amorphous fluororesins and resins having a fluorene skeleton, and photocuring Resin or the like can be used. Among these, it is particularly desirable that the outermost layer be an amorphous fluororesin that is inert to ozone and water and does not show corrosion due to the influence of moisture or corrosion of the substrate.

  Furthermore, since a resin having a fluorene skeleton (fluorene resin) has a structure in which four aromatic rings are bonded to one carbon atom (cardo structure), that is, the aromatic rings in the cardo structure are directed to different surfaces. The entire polymer cancels the optical anisotropy, and the amorphous nature is improved, so that high refraction and low birefringence are exhibited. Since the film thickness can be reduced with high refraction, the total film thickness can be reduced by using a fluorene resin, and the film thickness can be easily controlled.

  In the film formation process, it is desirable that the solvent evaporation rate is slow. For example, since the evaporation rate of the solvent is slower as the boiling point of the solvent is higher, the boiling point of the solvent is particularly preferably 180 ° C. or higher. A solvent that evaporates at a temperature that does not deform the substrate is desirable. For example, when an aluminum substrate is used, the boiling point of the solvent is preferably 280 ° C. or lower. As other physical properties relating to the solvent, it is preferable that there is little change in structure due to the environment and that it is odorless in the working environment.

  The form of the optical deflector in the present invention is not particularly limited by the present invention except that it has the polygon mirror of the present invention, and any form can be adopted as long as it is an optical scanning apparatus that can be used in an electrophotographic apparatus. obtain.

  The form of the optical scanning device of the present invention is not particularly limited by the present invention except that it includes an optical deflector, and can take any form as long as it can be used in electrophotographic equipment.

  For example, an optical scanning device includes a light source, an imaging optical system that focuses light emitted from the light source and forms an image, an optical deflector that reflects and deflects the imaged light, and the deflected light. A scanning lens that leads to the scanning surface is provided. In the optical scanning device of the present invention, the optical deflector includes the above-described polygon mirror in such a configuration.

  The electrophotographic apparatus of the present invention is not particularly limited by the present invention except that it includes the above-described optical scanning device. For example, the electrophotographic apparatus of the present invention includes an electrophotographic apparatus, and the configuration thereof includes a photoconductor. Charging means, exposure means for exposing a charged photoreceptor to form a latent image, toner image forming means for supplying toner to the latent image to form a toner image, and transfer for transferring the toner image to a transfer material And a cleaning means for removing residues and foreign matters on the surface of the photoreceptor, and the optical scanning device is provided as the exposure means.

  Hereinafter, the present invention will be described in detail based on examples.

  In the present embodiment, a resin film having a fluorene skeleton as the first layer is formed on an aluminum polygon mirror having reflecting surfaces on two opposite surfaces (see FIG. 2), and amorphous fluorine is formed as the outermost layer. It is shown that the resin film is formed by rotating the coating direction in the reverse direction, and the uniformity of the reflectance depending on the incident angle and position, which is a required characteristic of the polygon mirror, is obtained. As the solvent in the rotary wet film formation method, PGMEA is used as a resin having a fluorene skeleton, and THF is used as an amorphous fluororesin.

Example 1
A polygon mirror made of aluminum having four reflecting surfaces is passed through 10 axes as shown in FIG. Next, plasma treatment was performed for 10 seconds in order to improve the adhesion to the substrate. Subsequently, after reflecting the reflective surface of the polygon mirror for 10 seconds at 40 rpm in a liquid tank filled with a resin liquid having a fluorene skeleton of 1.5 wt% (EG-200: manufactured by Osaka Gas Chemical Co., Ltd.) A thin liquid film was formed by rotating in one direction at 4000 rpm for 70 seconds, and baking was performed at 180 ° C. for 30 minutes.

  Next, a primer (CT-P10: manufactured by Asahi Glass Co., Ltd.) is applied as a pretreatment for improving the adhesion with the resin film, and a 1 wt% amorphous fluororesin liquid (CTL-809A: manufactured by Asahi Glass Co., Ltd.) is used. The reflective surface of the polygon mirror was immersed in a filled liquid tank at 40 rpm for 10 seconds, pulled up from the liquid tank, rotated in the opposite direction at 4000 rpm for 70 seconds to form a thin liquid film, and baked at 180 ° C. for 30 minutes. .

  From the above, on the reflecting surface, a resin film having a fluorene skeleton with a film thickness of approximately 50 nm and an amorphous fluororesin film with a film thickness of approximately 30 nm are formed on four reflecting surfaces, and the reflectance at incident angles of 10 ° and 70 °. The change was within 2%. Further, as a result of the condensation durability test and the ozone durability test performed on the polygon mirror obtained in this way, no decrease in reflectance was observed. Therefore, the two-layer optical film was very useful as a coating film for the reflection surface of the polygon mirror. It is effective for.

(Example 2)
A polygon mirror made of aluminum having four reflecting surfaces is passed through 10 axes as shown in FIG. Next, plasma treatment was performed for 10 seconds in order to improve the adhesion with the substrate. Subsequently, after immersing the reflective surface of the polygon mirror in a liquid tank filled with a resin liquid having a fluorene skeleton of 1.8 wt% (EG-200: manufactured by Osaka Gas Chemical Co., Ltd.) at 40 rpm for 10 seconds, A thin liquid film was formed by rotating in one direction at 4000 rpm for 70 seconds, and baking was performed at 180 ° C. for 30 minutes.

  Next, a primer (CT-P10: manufactured by Asahi Glass Co., Ltd.) is applied as a pretreatment for improving the adhesion with the resin film, and a 0.2 wt% amorphous fluororesin liquid (CTL-809A: manufactured by Asahi Glass Co., Ltd.) is used. The reflective surface of the polygon mirror is immersed in a liquid tank filled with 10 seconds at 40 rpm, pulled up from the liquid tank, rotated in the opposite direction at 4000 rpm for 70 seconds to form a thin liquid film, and baked at 180 ° C. for 30 minutes It was.

  From the above, a resin film having a fluorene skeleton having a film thickness of about 60 nm and an amorphous fluororesin film having a film thickness of about 5 nm are formed on the four reflection surfaces on the reflection surface, and reflectivity at incident angles of 10 ° and 70 °. The change was within 2%. Further, as a result of the condensation durability test and the ozone durability test performed on the polygon mirror obtained in this way, no decrease in reflectance was observed. Therefore, the two-layer optical film was very useful as a coating film for the reflection surface of the polygon mirror. It is effective for.

  As a comparative example, the reflectance, film thickness distribution, cost, and quality according to the incident angle of a polygon mirror with a single layer of an amorphous fluororesin film in Comparative Example 1 and a polygon mirror with a single layer of an acrylic resin in Comparative Example 2 are as follows. evaluated. For the reflectance, the difference between the maximum value and the minimum value of the reflectance at an incident angle of 10 ° to 70 ° was compared. The film thickness distribution was compared for variations in the film thickness of the reflecting surface. The cost was compared with the total cost for manufacturing. The quality was compared with respect to poor reflectance related to film formation, for example, whether the absolute value is lower than the standard reflectance or the variation in reflectance due to the incident angle is within 2%. FIG. 5 shows Example 1, Example 2, Comparative Example 1, and Comparative Example 2.

  As can be seen from FIG. 5, in Examples 1 and 2, since the film thickness distribution is more uniform than in Comparative Examples 1 and 2, the difference between the maximum value and the minimum value of the reflectance depending on the incident angle can be controlled to be small. Reflectance variation due to the incident angle is suppressed, and the quality is stabilized. In addition, since the film thickness of the high-cost amorphous fluororesin can be reduced, the production cost can be reduced.

Claims (3)

A light reflecting surface formed by laminating a plurality of resin layers;
Only the outermost resin layer forming the plurality of light reflecting surfaces is an amorphous fluororesin layer,
The polygon mirror characterized in that the resin layer which is the base of the amorphous fluororesin layer is a fluorene resin layer. Scanner unit with polygon mirror according to claim 1. An image forming apparatus comprising the scanner unit according to claim 2 .

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