JP6269372B2 - Polygon mirror manufacturing method, polygon mirror, and image forming apparatus - Google Patents

Description

  The present invention relates to a polygon mirror having a plurality of mirror surfaces, a manufacturing method thereof, and an image forming apparatus including the polygon mirror.

  Conventionally, a polygon mirror having a base material of a polygon mirror formed of resin and a reflective film made of metal or the like formed on the surface of the base material is known (see Patent Document 1).

JP-A-5-323224

  However, in the conventional polygon mirror, when the heat or centrifugal force of the motor is applied to the polygon mirror, the resin base material may be deformed, and the reflective film may be peeled off from the base material.

  Therefore, an object of the present invention is to suppress peeling of a reflective film from a base material of a resin polygon mirror.

  In order to solve the above-mentioned problem, a polygon mirror manufacturing method according to the present invention is a polygon mirror manufacturing method having a plurality of mirror surfaces arranged so as to surround a predetermined rotation axis, and includes a plurality of mirror surfaces. A first step of performing a surface treatment by ion bombardment on at least the mirror-corresponding surface of a resin base material having a plurality of corresponding mirror-corresponding surfaces; and after the first step, at least the base material And a second step of forming a reflective film on the mirror corresponding surface.

  According to this, since the mirror-corresponding surface of the base material can be roughened at the molecular level by ion bombardment before forming the reflective film, the adhesion between the reflective film and the base material can be improved. Therefore, even when the heat or centrifugal force of the motor is applied to the polygon mirror, it is possible to prevent the reflective film from peeling off from the base material.

  In the first step, the ion bombardment may be performed by high-frequency plasma.

  In the second step, the reflective film may be formed by sputtering.

  According to this, the adhesion between the reflective film and the substrate can be increased.

  Further, after the second step, a third step of forming a dielectric protective film on the reflective film may be performed.

  According to this, it is possible to suppress oxidation of the reflective film and damage to the reflective film by the protective film.

  The protective film may be silicon dioxide, for example.

  The protective film may have a thickness of 35 nm or more and 235 nm or less.

  In this way, by setting the thickness of the protective film to 35 nm or more, oxidation of the reflective film can be suppressed. Further, by setting the thickness of the protective film to 235 nm or less, the deformation amount of the mirror corresponding surface before and after the formation of the protective film can be set to λ / 2 or less. Here, λ is the wavelength of light reflected by the polygon mirror, for example, 788 nm.

  In the second step, after forming an adhesion layer on the mirror-corresponding surface for enhancing adhesion between the base material and the reflection film, the reflection film may be formed on the adhesion layer. .

  According to this, for example, when the reflective film is formed by vapor deposition, the adhesion between the substrate and the reflective film can be improved by the adhesion layer.

  The adhesion layer may be, for example, silicon dioxide.

  According to this, for example, when forming a protective film of silicon dioxide on the reflective film, the adhesion layer can be formed with the same material as the protective film, so the same target in the manufacturing apparatus can be used and produced. Can be improved.

  Further, the thickness of the adhesion layer may be equal to or less than the thickness of the protective film.

  Moreover, the said base material may be formed from cyclic olefin resin.

  According to this, compared with the base material formed, for example from PMMA (Polymethyl Methacrylate) etc., the adhesiveness of a base material and a reflecting film can be improved.

  Further, the base material may have a Young's modulus of 2500 MPa or more.

  According to this, the deformation of the polygon mirror during rotation of the polygon mirror can be suppressed.

  The substrate may have a Poisson's ratio of 0.34 or more and 0.38 or less.

  The reflective film may contain aluminum as a main component.

  The thickness of the reflective film may be 45 nm or more and 105 nm or less.

  Thus, by setting the thickness of the reflective film to 45 nm or more, it is possible to suppress light from being transmitted through the reflective film. Moreover, the reflective film formation time can be shortened by setting the thickness of the reflective film to 105 nm or less.

  Further, at least in the first step and the second step, a plurality of the base materials may be arranged in the direction of the rotation axis, and surface treatment and formation of a reflective film may be simultaneously performed on the plurality of base materials.

  According to this, since a plurality of base materials can be processed together, productivity can be improved.

  Further, an interval may be provided between the plurality of mirror corresponding surfaces arranged in the rotation axis direction.

  According to this, since the reflection film or the like can be caused to wrap around each end face of the base material, it is possible to suppress the reflection film or the like from being peeled off from the mirror corresponding surface.

  The base material may have a protruding portion that protrudes in the direction of the rotation axis.

  According to this, since it is possible to form an interval between a plurality of mirror-corresponding surfaces simply by arranging a plurality of substrates so that the protruding portion of the substrate contacts an adjacent substrate, for example, each substrate The productivity can be improved as compared with the case where a spacer or the like is separately inserted between the spacers to leave a gap.

The polygon mirror according to the present invention includes a plurality of mirror corresponding surfaces arranged so as to surround a predetermined rotation axis, and a first end surface connecting the plurality of mirror corresponding surfaces on one side and the other side in the rotation axis direction. And a base material having a second end face, and a reflective film provided on the plurality of mirror corresponding faces.
The reflective film is formed over the first end surface, the mirror corresponding surface, and the second end surface.

  According to this, since the reflective film is formed over the first end surface, the mirror corresponding surface, and the second end surface, the adhesion between the reflective film and the substrate can be improved. For example, when the reflective film is formed only on the mirror-corresponding surface, the edge of the reflective film located at the boundary between the mirror-corresponding surface and the first end surface or the second end surface is easy to peel off. According to this, such peeling can be suppressed.

  The reflective film may be provided only on the outer peripheral portion at the first end face, and may be provided only on the outer peripheral portion at the second end face.

  According to this, the productivity of the polygon mirror can be improved as compared with the form in which the reflective film is formed on the entire surface of the first end face and the second end face.

  The image forming apparatus according to the present invention includes a first step of performing surface treatment by ion bombardment on at least the mirror-corresponding surface of a resin base material having a plurality of mirror-corresponding surfaces corresponding to the plurality of mirror surfaces. And a polygon mirror manufactured by a manufacturing method including, after the first step, a second step of forming a reflective film on at least the mirror corresponding surface of the base material.

  According to this, even when the heat or centrifugal force of the motor is applied to the polygon mirror, it is possible to prevent the reflective film from being peeled off from the resin base material.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a reflecting film peels from the base material of a resin-made polygon motor.

It is sectional drawing of the laser printer which concerns on one Embodiment. It is a top view of a scanner. It is sectional drawing (a) which shows a polygon mirror, and the enlarged view (b) which expands and shows a reflecting film and a protective film. It is sectional drawing which shows the process of shape | molding a base material with a metal mold | die. It is sectional drawing which cut the sputtering device by the plane orthogonal to the rotating shaft of a self-revolution apparatus. It is sectional drawing (a) which cut | disconnected the sputtering device by the plane along a rotating shaft, and the figure (b) which expands and shows the base material arranged up and down. It is sectional drawing which shows the modification which provided the contact | adherence layer between the mirror corresponding | compatible surface and the reflecting film. It is a figure which shows the experimental result in Example 1. FIG. It is a figure which shows the experimental result in Example 2. FIG. It is a figure which shows the experimental result in Example 3. FIG.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, the overall configuration of the laser printer 1 as an example of an image forming apparatus according to an embodiment of the present invention will be described, and then the features of the present invention will be described in detail.

  In the following description, the direction will be described with reference to the user when using the laser printer 1. That is, in FIG. 1, the left side toward the paper surface is “front side”, the right side toward the paper surface is “rear side”, the rear side toward the paper surface is “left side”, and the front side toward the paper surface is “right side”. To do. In addition, the vertical direction toward the page is defined as the “vertical direction”.

  As shown in FIG. 1, the laser printer 1 mainly includes a main body housing 2, a feeder unit 3, a scanner 4, a process cartridge 5, and a fixing device 8.

  The main body housing 2 includes a front cover 23 that can rotate with respect to the main body housing 2. By opening the front cover 23 to the front side and opening the insertion port 21B, the paper 33 can be inserted into the main body housing 2 from the insertion port 21B.

  The feeder unit 3 is located at the lower part of the main body housing 2 and includes a paper feed tray 31 for placing the paper 33 and a paper feed mechanism 32 for feeding the paper 33 on the paper feed tray 31. .

  The paper feed tray 31 includes a mounting table 31 </ b> A disposed at the lower part of the main body housing 2 and the above-described front cover 23. The paper feed mechanism 32 mainly includes a paper feed roller 32A, a separation roller 32B, and a separation pad 32C.

  In the feeder unit 3, the paper 33 placed on the paper feed tray 31 is sent out by the paper feed roller 32 </ b> A, and is separated one by one between the separation roller 32 </ b> B and the separation pad 32 </ b> C and directed toward the process cartridge 5. Are transported.

  The scanner 4 is provided on the front side in the main body housing 2 and scans laser light on the surface of a photosensitive drum 61 described later. Details of the configuration of the scanner 4 will be described later.

  The process cartridge 5 is located near the center of the rear side of the main body housing 2 and is provided above the paper feed mechanism 32. The process cartridge 5 is configured to be attachable to and detachable from the main body housing 2 toward the upper front side through an opening 21A formed when the top cover 24 rotatably provided on the main body housing 2 is opened. A drum unit 6 and a developing cartridge 7 are provided.

  The drum unit 6 includes a photosensitive drum 61, a charger 62 and a transfer roller 63. The developing cartridge 7 includes a developing roller 71 and a supply roller 72.

  In the developing cartridge 7, the toner stored in the toner storage chamber is supplied to the developing roller 71 by the supply roller 72, is frictionally charged, and is carried on the developing roller 71. In the drum unit 6, the surface of the rotating photosensitive drum 61 is uniformly charged by the charger 62 and then exposed by high-speed scanning of the laser light from the scanner 4. As a result, an electrostatic latent image based on the image data is formed on the surface of the photosensitive drum 61.

  Next, toner from the developing cartridge 7 is supplied to the electrostatic latent image, and a toner image is formed on the surface of the photosensitive drum 61. Thereafter, the sheet 33 is transported between the photosensitive drum 61 and the transfer roller 63, whereby the toner image carried on the surface of the photosensitive drum 61 is transferred onto the sheet 33.

  The fixing device 8 is located at the upper rear of the main body housing 2 and is disposed above the process cartridge 5. The fixing device 8 mainly includes a heating roller 81 and a pressure roller 82.

  In the fixing device 8 configured as described above, the toner transferred onto the paper 33 is thermally fixed while the paper 33 passes between the heating roller 81 and the pressure roller 82. The sheet 33 thermally fixed by the fixing device 8 is conveyed to a discharge roller 9 disposed on the downstream side of the fixing device 8 and is discharged from the discharge roller 9 onto the top cover 24.

  As shown in FIGS. 1 and 2, the scanner 4 includes a semiconductor laser 41, a coupling lens 42, an aperture stop 43, a cylindrical lens 44, an optical deflecting device 100, a scanning lens 45, and the like. The semiconductor laser 41 and the coupling lens 42 are light sources that emit a light beam, and each of these elements is supported by the housing 4A. The laser light emitted from the semiconductor laser 41 passes through the coupling lens 42, the aperture stop 43, the cylindrical lens 44, the optical deflecting device 100, and the scanning lens 45 in this order, as shown by the chain line, and forms an image on the photosensitive drum 61. The

  As shown in FIG. 2, the semiconductor laser 41 is a device that emits a diffusing laser beam. The light emitting element of the semiconductor laser 41 is blinked corresponding to the image to be exposed on the surface of the photosensitive drum 61 by a control device (not shown).

  The coupling lens 42 is a lens that converts the laser light emitted from the semiconductor laser 41 into a light beam. The aperture stop 43 defines the diameter of the laser beam converted into a light beam by the coupling lens 42. The cylindrical lens 44 is a lens that forms an image of the laser light that has passed through the aperture stop 43 in the sub-scanning direction (direction perpendicular to the paper surface of FIG. 2) on the polygon mirror 110 described later.

  As shown in FIG. 1, the light deflection apparatus 100 includes a polygon mirror 110 for deflecting laser light that has passed through the cylindrical lens 44 in the main scanning direction, a motor 120 for rotating the polygon mirror 110, a polygon mirror, and the like. And a pressing member 130 for attaching 110 to the motor 120. Details of the polygon mirror 110 will be described later.

  As shown in FIG. 2, the scanning lens 45 is a lens that forms an image of the light beam deflected by being reflected by the polygon mirror 110 on the surface of the photosensitive drum 61. Further, the scanning lens 45 has an fθ characteristic that scans light deflected by the polygon mirror 110 at a constant angular velocity on the surface of the photosensitive drum 61 at a constant speed.

  Next, details of the polygon mirror 110 will be described. In the following description, the directions will be described in the directions shown in FIG.

  As shown in FIGS. 3A and 3B, the polygon mirror 110 is a polygon mirror having four mirror surfaces M1 to M4 (see FIG. 2) arranged so as to surround a predetermined rotation axis SL. It mainly includes a resin base 110A, and a reflective film C1 and a protective film C2 formed on a part of the base 110A (a mirror corresponding surface 111A described later).

  The base 110A is made of a cyclic olefin resin, has a Young's modulus of 2500 MPa to 3500 MPa, and a Poisson's ratio of 0.34 to 0.38. The base 110A includes a main body 111 having four mirror corresponding surfaces 111A corresponding to the four mirror surfaces M1 to M4, and a protrusion 112 protruding downward from the main body 111 (in the direction of the rotation axis SL). And a second projecting portion 113 projecting upward from the main body portion 111 (in the direction of the rotation axis SL).

  The main body 111 has a prismatic shape having a substantially square bottom, and mainly includes four mirror corresponding surfaces 111A, a first end surface 111B connecting the upper ends of the mirror corresponding surfaces 111A, and each mirror corresponding surface 111A. And a second end face 111C connecting the lower ends. Then, the reflective film C1 is formed on each mirror corresponding surface 111A, and the protective film C2 is formed on the reflective film C1, so that the surface of the reflective film C1 or the protective film C2 is the mirror surface M1.

  The reflective film C1 and the protective film C2 are formed across the first end surface 111B, the mirror corresponding surface 111A, and the second end surface 111C. Specifically, the reflective film C1 and the protective film C2 are not formed on the entire first end surface 111B and the second end surface 111C, but are formed only on the outer peripheral portion of the first end surface 111B and the second end surface 111C. Here, the outer peripheral portion refers to a region from a position away from the rotation axis SL in the first end surface 111B or the second end surface 111C in the radial direction to the periphery of the first end surface 111B or the second end surface 111C.

  The reflective film C1 is made of a material mainly composed of aluminum. Specifically, the material of the reflective film C1 can be, for example, Al, Al-2% Si, Al—Nd, Al—Cu—Si, or the like. Further, the thickness of the reflective film C1 is set to a value of 45 nm or more and 105 nm or less.

  The protective film C2 is made of silicon dioxide that is a dielectric. The material of the protective film C2 may be a dielectric, and may be, for example, magnesium fluoride, aluminum oxide, yttrium oxide, hafnium oxide, zirconium oxide, tantalum oxide, titanium oxide, or the like. The thickness of the protective film C2 is set to a value of 35 nm or more and 235 nm or less.

  At the center of the main body 111, a through hole 111D for passing the rotating shaft of the motor 120 is formed so as to penetrate in the vertical direction. An inner peripheral surface D1 of the through hole 111D is a cylindrical surface, and an annular rib 114 that protrudes radially inward from the inner peripheral surface D1 is integrally formed on the inner peripheral surface D1.

  On the lower side of the rib 114, an inclined portion 115 for smoothly connecting the inner side surface 114A of the rib 114 and the inner peripheral surface D1 is integrally formed. Specifically, the inclined portion 115 has an inclined surface that extends from the inner side surface 114A of the rib 114 to the inner peripheral surface D1 and is inclined with respect to the axial direction.

  The protrusion 112 is formed in an annular shape centering on the rotation axis SL, and protrudes from the second end surface 111 </ b> C of the main body 111. The protrusion 112 is provided around the periphery (edge) of the through hole 111D, and the inner surface 112B is formed to be flush with the inner peripheral surface D1 of the through hole 111D (same position in the radial direction). . In addition, the thickness T1 in the radial direction of the protruding portion 112 is smaller than the thickness T2 of the main body 111.

  The second protrusion 113 protrudes from the first end surface 111B of the main body 111 and is formed in an annular shape centering on the rotation axis SL. Specifically, the second projecting portion 113 is provided around the through hole 111D, and the inner surface 113B is formed so as to be substantially in the same radial position as the inner peripheral surface D1 of the through hole 111D. Further, the radial thickness T3 of the second protrusion 113 is larger than the thickness T1 of the protrusion 112 and smaller than the thickness T2 of the main body 111.

Next, a method for manufacturing the polygon mirror 110 will be described in detail.
As shown in FIG. 4, first, the base material 110A is molded by injecting resin into a mold 200 having a molding surface that is shaped like the surface shape of the base material 110A of the polygon mirror 110 (molding step). Thereafter, using a sputtering apparatus 300 as shown in FIGS. 5 and 6, a reflective film C1 and a protective film C2 are formed on the mirror corresponding surface 111A of the base 110A (sputtering process). In addition, before explaining this sputtering process in detail, the structure of the sputtering apparatus 300 is demonstrated below.

  The sputtering apparatus 300 includes a self-revolution apparatus 310, a vacuum chamber 320, an environment change apparatus 330, an ion bombardment apparatus 340, a reflective film forming apparatus 350, and a protective film forming apparatus 360.

  The rotation / revolution device 310 is a device for rotating and revolving the plurality of base materials 110 </ b> A, and is mainly supported by a disk-shaped revolution stage 311 and a plurality of rotatably supported on the outer periphery of the revolution stage 311. The disk-shaped rotation stage 312 and the support shaft 313 fixed to the center of each rotation stage 312 are provided. The support shaft 313 is a rod-like member that passes through the through holes 111D of the plurality of base materials 110A and supports each base material 110A, and is formed with a diameter substantially the same as the inner side surface 114A of the rib 114. Thus, each base 110 </ b> A is mounted on the rotation stage 312 with the center aligned with the support shaft 313.

  In addition, the plurality of base materials 110A supported by the support shaft 313 are arranged so that the directions of the mirror corresponding surfaces 111A are aligned (so that the plurality of mirror corresponding surfaces 111A arranged in the vertical direction are located on substantially the same plane). It is desirable to set. According to this, the amount of wraparound to the end faces 111B and 111C of the reflective film C1 and the protective film C2 can be made substantially uniform. In addition, by aligning the orientations of the plurality of mirror corresponding surfaces 111A arranged in the vertical direction in this way, vapor deposition can be performed satisfactorily when film deposition is performed by vapor deposition.

  In addition, as a method of aligning the direction of the plurality of mirror corresponding surfaces 111A aligned vertically, for example, a method of measuring the angle of the mirror corresponding surface 111A by a robot and mounting it on the rotation stage 312, or the inner surface of the support shaft 313 and the rib 114 For example, a method of providing an engaging portion for aligning the angle of the mirror corresponding surface 111A with 114A can be used.

  The rotation stage 312 is a stage that supports the plurality of base materials 110 </ b> A, and is rotated about the axis of the support shaft 313 by a drive source and a drive mechanism (not shown). The revolution stage 311 has a rotation shaft 311A at the center thereof, and is configured to rotate around the rotation shaft 311A by a drive source and a drive mechanism (not shown). Here, the rotation stage 312 can be driven from the drive source and drive mechanism of the revolution stage 311 via a gear or the like.

  Further, atoms emitted from the reflective film forming apparatus 350 are attached to the protective film forming apparatus 360 or atoms emitted from the protective film forming apparatus 360 are closer to the center side than the respective rotating stages 312 on the revolution stage 311. A cylindrical shutter member 314 is provided to suppress adhesion to the reflective film forming apparatus 350.

  The vacuum chamber 320 is formed in a hollow columnar shape, and houses the autorevolution device 310 therein, and the environment changing device 330, the ion bombardment device 340, the reflection film forming device 350, and the protective film formation are formed on the side wall thereof. A device 360 is provided. Specifically, the environment change device 330, the ion bombardment device 340, the reflection film formation device 350, and the protection film formation device 360 are based on the environment change device 330 and the protection film in the rotation direction of the revolution stage 311. The forming device 360, the ion bombardment device 340, and the reflective film forming device 350 are arranged in this order.

  The environment changing device 330 is a device for changing the environment in the vacuum chamber 320, and supplies the gas necessary for operating the ion bombardment device 340, the reflective film forming device 350, and the protective film forming device 360 into the vacuum chamber 320. And a function of exhausting the gas in the vacuum chamber 320 to bring the vacuum chamber 320 into a vacuum state.

  The ion bombardment device 340 is a device for performing surface treatment by ion bombardment on each mirror corresponding surface 111A of the plurality of base materials 110A, and is opposed to the environment change device 330 in the radial direction of the vacuum chamber 320. Yes. The ion bombardment device 340 supplies electric power to the ion source 341 for applying an electromagnetic wave to the etching gas introduced into the vacuum by the environment changing device 330 to convert the etching gas into plasma, and supplying power to the ion source 341. An ion source power source 342 for applying a high frequency voltage to the device 310 (for example, the shutter member 314) is provided.

  In this ion bombardment device 340, ions are emitted from the ion source 341 toward each base material 110A, and ion etching (ion bombardment) is performed by the ions, so that each mirror corresponding surface 111A of each base material 110A has a molecular level. Fine irregularities are formed.

  The reflection film forming apparatus 350 is an apparatus for forming the reflection film C1 on each mirror-corresponding surface 111A subjected to surface treatment by ion bombardment. The reflection film forming apparatus 350 includes an environment change device 330 and an ion bombardment device 340 on the side wall of the vacuum chamber 320. It is provided in between. The reflective film forming apparatus 350 includes a first target 351 made of aluminum and a DC power supply 352 that ionizes the argon gas (rare gas) introduced into the vacuum by the environment changing apparatus 330 by applying a high voltage.

  In this reflective film forming apparatus 350, the argon gas ionized by the DC power source 352 collides with the first target 351, the atoms on the surface of the first target 351 are repelled and flew toward each substrate 110A, By being laminated on each mirror corresponding surface 111A, a reflective film C1 mainly composed of aluminum is formed on each mirror corresponding surface 111A.

  The protective film forming apparatus 360 is an apparatus for forming the protective film C2 on the reflective film C1, and faces the reflective film forming apparatus 350 in the radial direction of the vacuum chamber 320. The protective film forming apparatus 360 includes a second target 361 made of silicon dioxide, and an RF power source 362 (high frequency power source) that ionizes the argon gas introduced into the vacuum by the environment changing device 330 by applying a high voltage. . The frequency of the RF power source 362 can be set to 13.56 MHz, for example.

  In this protective film forming apparatus 360, the argon gas ionized by the RF power source 362 collides with the second target 361, so that atoms on the surface of the second target 361 are repelled and flew toward each substrate 110A. A protective film C2 made of silicon dioxide is formed on each reflective film C1 by being laminated on the reflective film C1 on each mirror corresponding surface 111A.

Next, the sputtering process will be described in detail.
In the sputtering process, first, the base materials 110A are sequentially stacked in the vertical direction (the direction of the rotation axis SL) on the rotation stages 312 so that the support shaft 313 passes through the through holes 111D of the base material 110A. At this time, the protrusion 112 provided below each base 110A is supported by the second protrusion 113 or the rotation stage 312 of the base 110A adjacent to the lower side, whereby two adjacent bases 110A. There is a gap between each of the four mirror corresponding surfaces 111A or between the four mirror corresponding surfaces 111A of the lowermost substrate 110A and the rotation stage 312. That is, spaces are formed above and below the mirror corresponding surfaces 111A arranged vertically.

  In this embodiment, since the upper surface of the rotation stage 312 is a flat surface, the distance between the mirror corresponding surface 111A of the lowermost substrate 110A and the rotation stage 312 corresponds to each mirror of the two adjacent substrates 110A. Although smaller than the interval between the surfaces 111A, the present invention is not limited to this. For example, by providing a protrusion having the same height as the second protrusion 113 of the base 110A on the upper surface of the rotation stage 312, all the intervals may be set to be the same. The interval is preferably set to 0.1 mm or more, preferably 0.3 mm or more, and more preferably 0.6 mm or more.

  Thereafter, after the inside of the vacuum chamber 320 is evacuated by the environment changing device 330, an etching gas is introduced into the vacuum chamber 320. Thereafter, by operating the revolution device 310, each base 110 </ b> A revolves around the rotation shaft 311 </ b> A of the revolution stage 311, and rotates around the support shaft 313. Thereafter, by operating the ion bombardment device 340, ions are emitted from the ion source 341 toward each mirror-corresponding surface 111A of each substrate 110A, and surface treatment is simultaneously performed on the plurality of substrates 110A. Fine irregularities at the molecular level are formed on the mirror corresponding surface 111A (first step).

  After the first step, the ion bombardment device 340 is stopped, the inside of the vacuum chamber 320 is evacuated by the environment changing device 330, and then argon gas is introduced into the vacuum chamber 320. Thereafter, by operating the reflective film forming apparatus 350, aluminum atoms are emitted from the first target 351 toward each mirror-corresponding surface 111A of each substrate 110A, and sputtering is simultaneously performed on the plurality of substrates 110A. Then, a reflective film C1 containing aluminum as a main component is formed on each mirror corresponding surface 111A (second step). At this time, even if aluminum atoms emitted from the first target 351 pass between the base materials 110 </ b> A, the atoms are prevented from reaching the protective film forming apparatus 360 by the shutter member 314.

  Further, since spaces are formed above and below the mirror corresponding surfaces 111A arranged in the vertical direction, when aluminum atoms are emitted to the mirror corresponding surface 111A, the atoms correspond to the mirror as shown in FIG. It goes around from the surface 111A to the first end surface 111B and the second end surface 111C and adheres to the end surfaces 111B and 111C. Thereby, the reflective film C1 is formed over the outer periphery of the first end surface 111B, the outer periphery of the mirror corresponding surface 111A, and the second end surface 111C.

  Thereafter, the reflective film forming apparatus 350 is stopped, and the protective film forming apparatus 360 is operated in the same argon gas environment as that in the second step, whereby silicon dioxide atoms are emitted from the second target 361, and a plurality of silicon dioxide atoms are emitted. Sputtering is simultaneously performed on the substrate 110A to form a protective film C2 made of silicon dioxide on the reflective film C1 of each mirror corresponding surface 111A (third step). At this time, even if the silicon dioxide atoms emitted from the second target 361 pass between the base materials 110 </ b> A, the atoms are prevented from reaching the reflective film forming apparatus 350 by the shutter member 314.

  Further, since spaces are formed above and below the mirror corresponding surfaces 111A arranged vertically, when atoms of silicon dioxide are emitted to the reflective film C1, the atoms are reflected in the reflective film as shown in FIG. It adheres so that C1 may be covered from the upper side, left-right direction outer side, and lower side. Thereby, the polygon mirror 110 is completed.

According to the above, the following effects can be obtained in the present embodiment.
Before forming the reflective film C1, the mirror-corresponding surface 111A of the base 110A is roughened at the molecular level by ion bombardment, so that the adhesion between the reflective film C1 and the base 110A can be improved. Therefore, even when the heat or centrifugal force of the motor 120 is applied to the polygon mirror 110, it is possible to prevent the reflective film C1 from peeling off from the base 110A.

  Since the reflective film C1 is formed by the sputtering method, the adhesion between the reflective film C1 and the substrate 110A can be improved as compared with the method of forming the reflective film by vapor deposition, for example.

  Since the protective film C2 is formed on the reflective film C1, the protective film C2 can suppress oxidation of the reflective film C1 and damage to the reflective film C1.

  Since the thickness of the protective film C2 is set to 35 nm or more, oxidation of the reflective film C1 and the like can be satisfactorily suppressed. Further, since the thickness of the protective film C2 is set to 235 nm or less, as will be described later, the deformation amount of the mirror corresponding surface 111A before and after the formation of the protective film C2 can be set to λ / 2 or less. Here, λ is the wavelength of light reflected by the polygon mirror 110, for example, 788 nm.

  Since the base material 110A is formed of a cyclic olefin-based resin, the adhesion between the base material 110A and the reflective film C1 can be improved as compared with a base material formed of, for example, PMMA (Polymethyl Methacrylate).

  Since the Young's modulus of the base material 110A is 2500 MPa or more, deformation of the polygon mirror 110 during rotation of the polygon mirror 110 can be suppressed.

  Since the reflective film C1 is made of a material mainly composed of aluminum, the reflectance in the region (near infrared) necessary for exposing the photosensitive drum 61 of the laser printer 1 can be increased. The reflection characteristics can be equivalent to those of a general aluminum polygon mirror. Further, since the reflective film C1 mainly composed of aluminum is formed on the resin base 110A, the material cost can be reduced as compared with a conventional general aluminum polygon mirror.

  Since the thickness of the reflective film C1 is set to 45 nm or more, it is possible to prevent light from being transmitted through the reflective film C1. Moreover, since the thickness of the reflective film C1 is set to 105 nm or less, the formation time of the reflective film C1 can be shortened.

  Since a plurality of the base materials 110A are arranged in the vertical direction and the surface treatment and the sputtering treatment are simultaneously performed on the plurality of base materials 110A, the plurality of base materials 110A can be collectively processed, thereby improving productivity. it can.

  By forming a space above and below the plurality of mirror-corresponding surfaces 111A arranged in the vertical direction, the reflective film C1 and the protective film C2 can wrap around the end surfaces 111B and 111C of the base 110A. It is possible to prevent the protective film C2 from being peeled off from the mirror corresponding surface 111A.

  Since the protrusions 112 and 113 protruding in the vertical direction are provided on the base material 110A, the base material 110A can be moved up and down simply by arranging a plurality of base materials 110A so that the protrusions 112 and 113 of the base material 110A are in contact with the adjacent base material 110A. A space can be formed above and below the plurality of mirror-corresponding surfaces 111A. Therefore, productivity can be improved as compared with, for example, inserting a spacer or the like between each base material or between the base material and the rotation stage to form a space.

  Since the reflective film C1 is formed over the first end surface 111B, the mirror corresponding surface 111A, and the second end surface 111C, the adhesion between the reflective film C1 and the substrate 110A can be improved. For example, when the reflective film is formed only on the mirror-corresponding surface, the edge of the reflective film located at the boundary between the mirror-corresponding surface and the first end surface or the second end surface is easy to peel off. According to this, such peeling can be suppressed.

  Since the reflective film C1 is provided only on the outer peripheral portion of each of the end faces 111B and 111C, the productivity of the polygon mirror 110 is improved as compared with, for example, a form in which the reflective film is formed on the entire first end face and second end face. be able to. Specifically, in the form in which the reflective film is formed on the entire surface of the first end face and the second end face, the base material must be rearranged so that the first end face and the second end face face the target. Such work can be omitted.

  Since the first to third steps are performed in one sputtering apparatus 300, the productivity is higher than, for example, a method in which an apparatus is provided for each process and the substrate is attached to and detached from the apparatus each time the process changes. Can be improved.

  Since the second step and the third step are performed in the same environment (in an argon gas atmosphere), productivity can be improved as compared with, for example, a mode in which the second step and the third step are performed in different environments. .

  In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below. In the following description, the same reference numerals are given to members having substantially the same structure as in the above embodiment, and the description thereof is omitted.

  In the embodiment, the reflective film C1 and the protective film C2 are formed on the mirror corresponding surface 111A. However, the present invention is not limited to this, and for example, as shown in FIG. 7, the mirror corresponding surface 111A (base material 110A) and the reflective surface are reflected. An adhesion layer C3 for enhancing the adhesion between the base 110A and the reflective film C1 may be provided between the film C1. In other words, in the second step, after the adhesion layer C3 is formed on the mirror corresponding surface 111A, the reflective film C1 may be formed on the adhesion layer C3.

  According to this, for example, when the reflective film C1 is formed by vapor deposition, the adhesion between the base 110A and the reflective film C1 can be improved by the adhesion layer C3.

  The material of the adhesion layer C3 can be, for example, silicon dioxide. According to this, when the silicon dioxide protective film C2 is formed on the reflective film C1 as in the above-described embodiment, the adhesion layer C3 can be formed of the same material as the protective film C2. The same target (second target 361) can be used, and productivity can be improved.

  Note that the thickness of the adhesion layer C3 may be equal to or less than the thickness of the protective film C2.

  In the above embodiment, ion bombardment is performed by high-frequency plasma, but the present invention is not limited to this, and ion bombardment may be performed by other methods.

  In the above embodiment, the reflective film C1 and the protective film C2 are formed by the sputtering method, but the present invention is not limited to this, and the reflective film and the protective film may be formed by, for example, vapor deposition.

  In the embodiment, the reflective film C1 and the protective film C2 are formed over the outer peripheral portion of the first end surface 111B and the outer peripheral portions of the mirror corresponding surface 111A and the second end surface 111C. However, the present invention is not limited to this, and the reflective film The protective film may be formed over the entire surface of the substrate. In this case, surface treatment by ion bombardment may be performed on the entire surface of the substrate.

  The materials of the reflective film C1, the protective film C2, the adhesion layer C3, and the base material 110A are not limited to the materials described above, and can be changed as appropriate.

  In the above embodiment, the polygon mirror 110 has a prismatic shape having a substantially square bottom surface. However, the present invention is not limited to this, and the polygon mirror is a prism having a polygonal bottom surface such as a regular pentagon or a regular hexagon. It may be a shape.

  In the above embodiment, the present invention is applied to the laser printer 1. However, the present invention is not limited to this, and the present invention may be applied to other image forming apparatuses such as a copying machine and a multifunction machine.

Below, Examples 1-4 about above-mentioned embodiment are described.
[Example 1]
In the experiment in Example 1, the first to third steps were performed using the same equipment (sputtering apparatus manufactured by Shibaura Mechatronics) as in the above embodiment. Various conditions of the experiment are as follows.

<Conditions for the first step>
・ Material of base material: Cyclic olefin resin ・ Etching gas: Argon gas ・ Flow rate of etching gas: 25 sccm (41.675 × 10 ⁻⁸ m ³ / s)
・ Power supply for ion source: 100W
・ Plasma time (time required for surface treatment): 30 seconds ・ Revolution speed of substrate: 20 rpm
・ Rotating speed of substrate: 60 rpm

<Conditions for the second step>
Back pressure (attainment pressure when evacuating the vacuum chamber): 5.0 × 10 ⁻³ Pa
・ Rare gas used: Argon gas ・ Flow rate of rare gas: 25 sccm (41.675 × 10 ⁻⁸ m ³ / s)
・ DC power supply power: 200W
・ Revolution speed of substrate: 20 rpm
・ Rotating speed of substrate: 60 rpm
-Gas pressure during film formation: 0.1 Pa
Reflective film material: Aluminum (Al)
Reflective film thickness: 50 nm

<Conditions for the third step>
・ Back pressure: 5.0 × 10 ⁻³ Pa
・ Rare gas used: Argon gas ・ Flow rate of rare gas: 25 sccm (41.675 × 10 ⁻⁸ m ³ / s)
・ Power of RF power supply: 500W
・ Revolution speed of substrate: 20 rpm
・ Rotating speed of substrate: 60 rpm
-Gas pressure during film formation: 0.1 Pa
・ Material of protective film: silicon dioxide (SiO ₂ )
・ Protective film thickness: 70 nm

  Under the conditions as described above, the polygon mirror according to Example 1 is manufactured by performing the first process to the third process, and the second process and the third process are performed without performing the first process. Such a polygon mirror was manufactured. Then, the following constant temperature and humidity test, thermal shock test, low temperature test and high temperature test were performed on the polygon mirror according to Example 1 and the comparative example.

<Constant temperature and humidity test>
After leaving the polygon mirror according to Example 1 and the comparative example for one week in an environment where the temperature is 60 ± 3 ° C. and the humidity is 90 ± 5% RH, a tape test (adhesive tape is attached to the mirror surface and peeled off). The state of peeling of the reflective film was examined by a test).

<Thermal shock test>
The temperature in the container containing the polygon mirror according to Example 1 and the comparative example was switched between −40 ° C. and 70 ° C. every other hour, and this operation was repeated 10 times. I investigated.

<Low temperature storage test>
The polygon mirror according to Example 1 and the comparative example was allowed to stand for 1 week in an environment where the temperature was −40 ° C., and then the peeling state of the reflective film was examined by a tape test.

<High temperature storage test>
The polygon mirror according to Example 1 and the comparative example was allowed to stand for 1 week in an environment where the temperature was 70 ° C., and then the state of peeling of the reflective film was examined by a tape test.

  The experimental results of each test are as shown in FIG. From each experiment, it was confirmed that the reflection film did not adhere to the adhesive tape in all the tests in the polygon mirror according to Example 1 (OK). Further, in the polygon mirror according to the comparative example, it was confirmed that the reflective film adhered to the adhesive tape and peeled off in the constant temperature and humidity leaving test and the thermal shock test (NG). In the low temperature standing test and the high temperature standing test, It was confirmed that the reflective film did not adhere to the adhesive tape (OK). As described above, in the polygon mirror according to Example 1, it was confirmed that the mirror-corresponding surface and the reflective film were in good contact.

  In Example 1, in addition to the above-described experiment, an experiment for confirming the wettability of the mirror corresponding surface was performed before and after the first step (ion etching). As a result, the contact angle (angle formed between the mirror support surface and the surface of the water droplet) is 80 ° or more on the mirror-corresponding surface that is not ion-etched, whereas the contact angle is on the mirror-corresponding surface that is ion-etched. It was confirmed that it decreased to 40 ° or less. That is, it was confirmed that the mirror-corresponding surface before forming the reflecting film in Example 1 has higher wettability (high adhesion) than the mirror-corresponding surface before forming the reflecting film in the comparative example.

[Example 2]
In Example 2, the deformation amount of the mirror corresponding surface before and after the formation of the reflective film on the mirror corresponding surface was examined. Specifically, the surface shape of the mirror corresponding surface was measured with a Fizeau interferometer, and the first step was performed under the same conditions as in Example 1. Then, after performing the 2nd process on the same conditions as Example 1, the surface shape of the surface of a reflective film was measured with the Fizeau interferometer. Then, the difference between the surface shape of the mirror corresponding surface before the formation of the reflective film and the surface shape of the surface of the reflective film was calculated as the deformation amount before and after the film formation. In Example 2, an experiment was performed in which the thickness of the reflective film was changed from 50 nm to 100 nm.

  The experimental results of these experiments are as shown in FIG. According to each experiment, the deformation amount before and after the deposition of the four mirror-corresponding surfaces (indicated by 1, 2, 3, and 4 on the horizontal axis) is 0 regardless of whether the thickness of the reflective film is 50 nm or 100 nm. It was confirmed that it can be suppressed to less than 1λ. Here, λ is 788 nm.

[Example 3]
In Example 3, the deformation amount of the mirror corresponding surface before and after the formation of the protective film was examined. Specifically, the surface shape of the mirror corresponding surface was measured with a Fizeau interferometer, and after performing the third step under the same conditions and in the same manner as in Example 1, the surface shape of the surface of the protective film was measured with a Fizeau interferometer. . Then, the difference between the surface shape of the mirror corresponding surface before the formation of the protective film and the surface shape of the surface of the protective film was calculated as a deformation amount before and after the film formation. In Example 3, an experiment was performed in which the thickness of the protective film was changed from 70 nm to 30 nm, 40 nm, 50 nm, 60 nm, 110 nm, 140 nm, 150 nm, and 235 nm.

The experimental results of these experiments are as shown in FIG. In addition, the line extended up and down from the point of the measurement result in FIG. 10 shows the range of variation, specifically, the range of 3σ (σ: standard deviation). Here, σ was calculated from the deformation amounts of the four mirror corresponding surfaces. Each experiment confirmed that the amount of deformation before and after film formation can be suppressed to 0.5λ or less when the thickness of the protective film (SiO ₂ film) is 235 nm or less. Here, λ is 788 nm.

[Example 4]
In Example 4, an experiment was conducted to examine the adhesion between the substrate and the reflective film depending on the presence or absence of the adhesion layer. In this experiment, after performing the first step under the same conditions as in Example 1, the second to third steps (formation of the adhesion layer, the reflective film, and the protective film) were performed by vapor deposition. Specifically, it is as follows.

<Conditions for the second step>
(1) Adhesion layer forming step / material / thickness of adhesion layer: silicon dioxide (SiO ₂ ) 50 nm
・ Back pressure: 5.0 × 10 ⁻⁵ Pa
・ Deposition time: 5 min
-Electron beam current: 100 mA
(2) Reflection film formation process / Reflection film material / thickness: aluminum (Al) / 50 nm
・ Back pressure: 5.0 × 10 ⁻⁵ Pa
・ Deposition time: 5 min
-Electron beam current: 80 mA

<Conditions for the third step>
-Material of protective film-Thickness: Silicon dioxide (SiO ₂ )-70 nm
・ Back pressure: 5.0 × 10 ⁻⁵ Pa
・ Deposition time: 10 min
-Electron beam current: 100 mA

  Under the conditions as described above, the polygon mirror with the adhesion layer according to Example 4 is manufactured by performing the first to third processes, and the adhesion layer forming process in the second process is not performed. A polygon mirror without such an adhesion layer was produced. And the tape test was done with respect to the polygon mirror concerning Example 4 and a comparative example.

  As a result, in Example 4 having the adhesion layer, it was confirmed that the reflection film was not peeled off even when the tape test was performed, and in the comparative example having no adhesion layer, it was confirmed that the reflection film was peeled off by the tape test. It was. Therefore, it was confirmed that when the reflective film is formed by vapor deposition, the reflective film can be better adhered to the mirror-corresponding surface when the adhesive layer is provided.

110 polygon mirror 110A base material 111A mirror corresponding surface C1 reflective film C2 protective film C3 adhesion layer M1 mirror surface SL rotation axis

Claims (18)

A method of manufacturing a polygon mirror having a plurality of mirror surfaces arranged so as to surround a predetermined rotation axis,
A surface treatment by ion bombardment is performed in a container on at least the mirror-corresponding surface of a resin base material having a plurality of mirror-corresponding surfaces corresponding to the plurality of mirror surfaces by an ion bombardment device that emits ions. 1 process,
After the first step , the environment in the container is changed to an environment different from the first step, and a sputtering method for emitting atoms forming the reflective film from the reflective film forming apparatus is used to at least the substrate. A second step of forming a reflective film on the mirror corresponding surface in the container ,
In the first step and the second step, the rotation stage for supporting the substrate, Rutotomoni to rotate the substrate about the axis of rotation, rotates around the rotation axis, the rotation stage the outer peripheral portion The substrate is revolved by a revolving stage that supports
The method of manufacturing a polygon mirror, wherein the ion bombardment device and the reflection film forming device are arranged outside the revolution stage and at different positions in the rotation direction of the revolution stage . The base material has a through-hole centered on the rotation axis,
The method for manufacturing a polygon mirror according to claim 1, wherein the rotation stage includes a support shaft that penetrates the through hole. 3. The polygon according to claim 1, wherein a shutter member that shields atoms emitted from the reflection film forming device is provided on a center side of the revolution stage with respect to the rotation stage. Mirror manufacturing method. In the first step, the ion bombardment method for manufacturing a polygon mirror as claimed in any one of claims 3, characterized in that performed by high-frequency plasma. After the second step, the polygon mirror according to any one of claims 1 to 4, characterized in that it comprises a third step of forming a protective film of dielectric on said reflective film Production method. The method for manufacturing a polygon mirror according to claim 5 , wherein the protective film is silicon dioxide. The method of manufacturing a polygon mirror according to claim 5 or 6 , wherein the thickness of the protective film is 35 nm or more and 235 nm or less. In the second step, after forming an adhesion layer on the mirror corresponding surface to enhance adhesion between the base material and the reflection film, the reflection film is formed on the adhesion layer,
8. The method of manufacturing a polygon mirror according to claim 5 , wherein a thickness of the adhesion layer is equal to or less than a thickness of the protective film. 9. The method for manufacturing a polygon mirror according to claim 8 , wherein the adhesion layer is silicon dioxide. The method for manufacturing a polygon mirror according to any one of claims 1 to 9 , wherein the base material is formed of a cyclic olefin-based resin. The method for manufacturing a polygon mirror according to claim 10 , wherein the base material has a Young's modulus of 2500 MPa or more. The polygon mirror manufacturing method according to claim 10 or 11 , wherein the substrate has a Poisson's ratio of 0.34 or more and 0.38 or less. The reflective film manufacturing method of the polygon mirror as claimed in any one of claims 12, characterized in that the main component of aluminum. The thickness of the reflective film, the manufacturing method of the polygon mirror as claimed in any one of claims 13, characterized in that at 45nm or more 105nm or less. At least in the first step and the second step, a plurality of the base materials are arranged in the rotation axis direction, and surface treatment and formation of a reflective film are simultaneously performed on the plurality of base materials. The manufacturing method of the polygon mirror of any one of Claim 14 . 16. The method for manufacturing a polygon mirror according to claim 15 , wherein an interval is provided between the plurality of mirror-corresponding surfaces arranged in the rotation axis direction. The method for manufacturing a polygon mirror according to claim 16 , wherein the base member has a protruding portion protruding in the rotation axis direction. The base material has a first end surface and a second end surface that connect the plurality of mirror-corresponding surfaces on one side and the other side in the rotation axis direction;
The said 2nd process WHEREIN: The said reflecting film is formed only in the range over the outer peripheral part of the said 1st end surface, the said mirror corresponding | compatible surface, and the outer peripheral part of the said 2nd end surface. Polygon mirror manufacturing method.

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