JP2006133722A - Manufacturing method of optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a manufacturing method of optical element capable of easily manufacturing an optical element having an anti-reflection characteristic made by forming a fine structure on a flat surface or on a surface having a finite curvature. <P>SOLUTION: In the manufacturing method of optical element, the optical element having fine protruded shapes on the surface is manufactured by using a die in which a plurality of recessed parts of fine recessed shape are formed independently in the normal direction of the face on the flat surface or on the surface having a finite curvature, wherein the depth of the recessed part of the die is ≥1.5 times and ≤10 times for the height in design value of protruded parts of the optical element and the design value of lattice ratio of the die is made to be lower than the design value of the lattice ratio of the optical element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing an optical element having a function of suppressing the amount of light reflected from the interface at the light incident / exit surface. For example, the present invention relates to an imaging device such as a camera or video camera, a projection device such as a liquid crystal projector, and an electronic device. It is suitable for an optical system such as an optical scanning device for photographic equipment.

  In general, an optical element that needs to suppress the amount of reflected light on the surface obtains desired reflection characteristics by laminating a single layer or a plurality of layers with an optical film having a different refractive index on its surface to a thickness of several tens to several hundreds of nanometers. . In order to form these optical films, vacuum film formation methods such as vapor deposition and sputtering, and wet film formation methods such as dip coating and spin coating are used. Regardless of which film forming means is used, the optical element substrate must be processed and then formed into a film, which makes it difficult to manufacture and there are restrictions in reducing the cost.

  On the other hand, it is known that the amount of reflected light at the interface can be suppressed by forming a fine shape with a pitch equal to or less than the design wavelength on the surface of the optical element without using an optical film. If the fine shape can be formed on the mold by utilizing this principle and the optical element can be manufactured together with the formation of the mother shape (base), the manufacturing cost can be ultimately reduced.

  Conventionally, a semiconductor process has been widely used as a technique for forming a fine-shaped optical element (microstructure element) called SWS (SubWave-lengthStructure) (see Patent Document 1).

  Patent Document 1 proposes a fine-structure grating determined by a grating pitch, a grating depth, a grating ratio (lattice constant), and the like with respect to a corresponding wavelength.

  Note that the grating ratio referred to here means that the “volume occupied by the convex portion” is “the volume of the convex portion + the volume of the convex portion + This indicates how much the volume of the concave portion is. When actually measuring and calculating the lattice ratio, use a measuring device such as an atomic force microscope or an electron microscope for an area containing multiple irregularities, ideally an area containing several tens to hundreds of irregularities. It is desirable to measure using and calculate as an average ratio.

  On the other hand, as one of the methods for producing SWS simply (cheaply), a method of forming using fine particles has been proposed (see Patent Document 2).

  When using fine particles, it is possible to form SWS in a large area at once, but because the SWS is formed by continuously arranging the fine particles uniformly, the volume ratio of the substrate and the atmosphere that determines the reflection characteristics And the aspect ratio are difficult to control, and it is difficult to obtain an ideal antireflection effect.

On the other hand, an anodic oxidation method is known as a method for easily forming an SWS in a large area and arbitrarily controlling the aspect ratio. A fine hole (hole) is formed perpendicularly to the surface by energizing and oxidizing a metal such as aluminum as an anode in the acidic electrolyte. Utilizing this fact, a method of regularly arranging holes, a method of filling holes with different materials, and the like have been developed (see Patent Documents 3 and 4).
JP 2003-185955 A JP 2000-071290 A JP-A-2-254192 JP-A-10-121292

  An antireflection effect can be obtained by forming the fine hole on the optical surface of the mold by manufacturing the mold using the above method, and performing transfer simultaneously with the mother shape. As a result, the optical element can be more easily manufactured without forming the optical film, which has been conventionally performed, in the post-molding process.

  However, when trying to transfer the protrusion shape by molding into the fine hole shape manufactured by the process such as anodization, the mother shape can satisfy the desired accuracy due to problems such as air retention and resin fluidity. Even in this case, only the fine hole-shaped portion is unfilled, and it is difficult to obtain a desired shape.

As a method for transferring such a hole shape, there is a heat cycle molding method using a cartridge type heater or the like. It is possible to fill the fine hole-shaped portion with resin using this heat cycle molding method .

  However, compared with the conventional molding method, the heat cycle molding method requires a heating time of the mold temperature and requires a cooling time longer than the conventional one, as compared with the conventional optical element having no SWS surface. One of the objects of the present invention is that the manufacturing cycle increases because the molding cycle is extended, and the manufacturing cost (cost) is not superior because it requires equipment investment. There is a problem that it becomes impossible to provide an optical element having a SWS surface in a simple (inexpensive) manner.

  Furthermore, with regard to the lattice ratio, when a mold was manufactured with the desired lattice ratio of the molded product, when the molding was examined using a normal molding method and heat cycle molding, the protrusion shape caused expansion due to overpacking, and the desired lattice ratio was obtained. The optical performance cannot be satisfied and the optical performance is degraded.

  An object of the present invention is to provide a method of manufacturing an optical element that can easily manufacture an optical element having antireflection characteristics in which a fine structure is formed on a plane or a surface having a finite curvature.

  Another object of the present invention is to provide an optical element manufacturing method capable of easily manufacturing an optical element having a simple and stable antireflection characteristic by molding.

  Another object of the present invention is to mount an optical element obtained by the above method in an optical system to obtain an optical system having good optical characteristics.

  The method of manufacturing an optical element according to the first aspect of the present invention uses a mold in which a plurality of concave recesses are formed independently on a plane or a plane having a finite curvature independently of the normal direction of the plane. In the optical element manufacturing method for manufacturing an optical element having a convex microstructure lattice corresponding to the concave portion, the depth of the concave portion of the mold is the height of the design value of the convex portion of the optical element. On the other hand, it is characterized by being 1.5 times or more and 10 times or less.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the lattice ratio of the mold is lower than the lattice ratio of the molded product.

  The invention of claim 3 is characterized in that, in the invention of claim 1, it includes a step of injection molding using the mold.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the mold is manufactured by anodization.

  A fifth aspect of the present invention is characterized in that, in the first or second aspect of the present invention, the mold has a shape in which a lattice ratio of the optical element is 30% to 70%.

  A scanning lens according to a sixth aspect of the invention is manufactured using the method for manufacturing an optical element according to any one of the first to fourth aspects.

  According to the present invention, an optical element having antireflection characteristics in which a fine structure is formed on a plane or a plane having a finite curvature can be easily manufactured.

  In addition, according to the present invention, an optical surface is provided by using an optical element provided with a plurality of projections having a fine projection shape (convex shape or concave shape) having an antireflection function on a plane or a surface having a finite curvature. Therefore, it is possible to achieve an optical system that can eliminate the problems caused by ghosts.

  In addition, according to the present invention, it is possible to obtain an optical element in which a projection having a fine shape that satisfies a predetermined design shape is formed on a mother shape.

  In addition, according to the present invention, by mounting the optical element on an optical device, it is possible to eliminate problems caused by reflected light on the surface of the optical element, and to realize high brightness and energy saving by increasing the amount of transmitted light. An optical instrument capable of achieving the above can be achieved.

  Embodiments of the present invention will be described below with reference to the drawings.

The definition of SWS (SubWave-lengthStructure) used in this embodiment is shown below.
As the fine structured lattice (SubWave-lengthStructure) used in this embodiment, a lattice pitch P that satisfies a condition as a so-called zero-order lattice is selected. The microstructure grating is called SWS (SubWave-length Structure) and has a grating pitch smaller by one to two digits than a normal diffraction grating, and is intended for use of zero-order light having no diffraction action.

  The grating pitch is less than the submicron order smaller than the design wavelength.

  The zero-order grating is a grating that does not generate diffracted light other than the zero-order grating in the microstructure grating.

  FIG. 1 is a cross-sectional view of an essential part of an optical element (molded product) and a mold in a molding process of Example 1 of the present invention, and FIG. 1 (A) is a photograph of the mold before molding with an electron microscope or an atomic force microscope. FIG. 2 (B) is a schematic diagram of a plan view of an optical element molded by the mold taken with an electron microscope or an atomic force microscope, and FIG. 3 is a mold after molding. It is a principal part perspective view (schematic diagram) at the time of image | photographing the protrusion part (lattice part) of the optical element taken out from the type | mold with an atomic force microscope or an electron microscope.

  In the figure, 9 is a base shape (base) of an optical element (fine structure element) having a flat surface or a finite curvature, and is formed on the surface independently in the normal direction of the surface, and has an antireflection function. A plurality of fine protrusion-shaped protrusions (lattice parts) 8 are formed.

  In this embodiment, an antireflection function is provided on the surface of the mother shape 9 of the optical element by using the mold 10 provided with a plurality of concave portions having a predetermined depth on a plane or a surface having a curvature. A plurality of fine protrusion-shaped protrusions 8 are simultaneously formed to manufacture an optical element having a simple antireflection structure.

  Reference numeral 10 denotes a mother shape (base) of a mold for molding the optical element. In this embodiment, the hole depth (lattice height) h1 of the mold is set to be 1.5 times or more and 10 times or less than the projection height h2 of the design value of the optical element. As a result, this embodiment solves the problem that the projection height of the finely shaped portion (projection portion) 8 of the optical element cannot achieve the design value due to problems such as air retention and resin fluidity.

  Reference numeral 11 denotes a hole of the mold 10 so that the lattice ratio of the mold 10 is lower than the desired (design value) lattice ratio of the molded product. That is, the diameter is set so that the volume occupied by the hole 11 is smaller than the volume of the design value. As a result, in this embodiment, it is possible to prevent the projection-shaped diameter of the projection 8 from being bulged and becoming a desired lattice ratio.

  FIG. 2A shows a state where the diameter of the protrusion 8 of the optical element taken out from the mold 10 is larger than the diameter of the hole 11 of the mold 10.

  The shape of the protrusion 8 may be a columnar shape, a conical shape, a polygonal column shape, or a polygonal pyramid shape.

  More preferably, the hole depth h1 of the mold is set to be not less than 3 times and not more than 8 times the projection height h2 of the design value of the optical element.

  Here, an optimal method for calculating the lattice shape of the optical element will be described with reference to FIG.

  When the oscillation wavelength of the laser light source to be used is 780 nm, as shown in the above-mentioned Patent Document 1, it is assumed that the protrusion pitch is a protrusion having a grating pitch P of 300 nm and a grating depth of 160 nm because of the requirement of the zero-order grating. Also, the result of optical simulation when the refractive index of the lens material is n = 1.524 and the grating ratio is changed is shown.

  From the simulation results shown in FIG. 4, having the protrusions 8 with a lattice ratio of 49% on the base shape 9 was the optimum design value for carrying out this example.

  As can be seen from the simulation results of FIG. 4, when the reflectance target value is 1.0%, the target value can be achieved if the grating ratio is between 25% and 64%. The optimum lattice ratio is not limited to the above-described lattice ratio. Furthermore, when the reflectance target value is 2.0% or less, the target value can be achieved if the grating ratio is between 16% and 81%.

  In this embodiment, it is preferable to use a mold having a lattice ratio of 30% to 70%. More preferably, a mold having a lattice ratio of 40% to 60% is used.

  In this embodiment, the holes (projections) may be arranged in a regular arrangement or a random arrangement as long as the lattice ratio is satisfied.

  Next, the manufacturing method 1 of the optical element of a present Example is demonstrated.

  In the present embodiment, a step of producing a mold having an inverted shape with respect to the mother shape of the optical element, and a depth h1 of a hole which is an inverted shape of a fine protrusion shape on the mirror surface portion of the mold are represented by the optical element. The step of manufacturing at a depth not less than 1.5 times and not more than 10 times the projection height h2 of the design value of the above, and the area of the hole which is the inverted shape of the fine projection shape on the raised surface portion of the mold The optical element is manufactured using a process of manufacturing the ratio at a ratio lower than a desired area ratio of the optical element and an injection molding process using the mold.

A hole diameter corresponding to the protrusion shape of the protrusion was produced on the mother shape of the mold using anodization, and the optical element was molded. At this time, the resin is a cycloolefin polymer (manufactured by ZEON: ZEONEX) and an injection molding machine (SS180) manufactured by Sumitomo Heavy Industries, Ltd. is used, the resin temperature is 270 ° C., the injection speed is 30 mm / s, and the holding pressure is 700 kgf / Molding was performed under the conditions of cm ² and the projection height h2 of the optical element was measured with an atomic force microscope. As a result, the projection had an average height of 90 nm and a projection having a desired height could not be molded. .

  The lattice ratio was also measured with an electron microscope. The mold ratio was 56%, but due to the expansion caused by overpacking, the desired lattice ratio could not be 70% and the spectroscopic ratio could be reduced. When the reflectance was measured using a photometer, the reflectance was 4.5% in the case of a normal optical surface was 4.0%, and the target could not be achieved.

  Here, the mold hole depth h1 corresponding to the projection height h2 of the optical element is changed to 800 nm, the mold lattice ratio is changed to 40%, and molding is performed under the above conditions. As a result of measuring the height h2, the projection height h2 was 160 nm, and the grating ratio was measured with an electron microscope. The grating ratio was 56%, and the reflectance was measured with a spectrophotometer, resulting in 0.8%. An optical element having a desired shape can be obtained (see FIGS. 1 and 2).

  The anodic oxidation means that aluminum is immersed in an electrolyte solution composed of sulfuric acid, oxalic acid, and phosphoric acid as a positive electrode, and a DC power source is connected to the negative electrode so that the aluminum is energized. This is a technique for forming submicron-order pores in a direction perpendicular to the surface by oxidation.

  Next, a second embodiment of the present invention will be described.

  The difference between the present embodiment and the first embodiment is that the laser light source used has an oscillation wavelength of 405 nm. Other configurations and optical actions are substantially the same as those in the first embodiment, and the same effects are obtained.

  That is, the oscillation wavelength of the laser light source used in this embodiment is 405 nm. Although no particular simulation results are shown here, projections having a projection shape with a grating pitch P of 156 nm and a grating depth of 82 nm are assumed by the same method as in the first embodiment. Further, by providing a projection having a refractive index of the lens material of n = 1.524 and a lattice ratio of 60% on the mother shape, an optimum design value was obtained in carrying out this embodiment.

  As in Example 1, when the reflectance target value is 1.0%, the target value can be achieved if the grating ratio is between 25% and 64%, but it is optimal. The lattice ratio is not limited to the above-described lattice ratio.

  Here, the area ratio was set for the purpose of increasing the area ratio among the values falling within the above range and improving the fluidity of the resin, which is considered to be one of the unfilled effects. Furthermore, when the reflectance target value is 2.0% or less, the target value can be achieved if the grating ratio is between 16% and 81%.

In this embodiment, the holes (projections) may be arranged in a regular arrangement or a random arrangement as long as the lattice ratio is satisfied. Next, the optical element manufacturing method 2 of this embodiment will be described. .

A hole diameter corresponding to the protrusion shape of the protrusion was produced on the mother shape of the mold using anodization, and the optical element was molded. At this time, the resin is a cycloolefin polymer (manufactured by ZEON: ZEONEX) and an injection molding machine (SS180) manufactured by Sumitomo Heavy Industries, Ltd. is used, the resin temperature is 270 ° C., the injection speed is 30 mm / s, and the holding pressure is 700 kgf / Molding was performed under the conditions of cm ² and the projection height of the optical element was measured with an atomic force microscope. As a result, the average projection height was 45 nm, and projections with a desired height could not be molded. Also, with respect to the lattice ratio, the mold lattice ratio is 60%, whereas the protrusions expand due to overpacking by molding, and when measured with an electron microscope, 70% cannot be obtained as the desired lattice ratio. When the reflectance was measured using a spectrophotometer, the reflectance was 4.5% in the case of a normal optical surface, which was 3.0%, and the target could not be achieved.

  Here, the hole depth h1 of the mold corresponding to the projection height h2 of the optical element is changed to 300 nm, the mold lattice ratio is changed to 40%, and molding is performed under the above conditions, and the projection is made with an atomic force microscope. As a result of measuring the height h2, the projection height h2 was 85 nm. When the grating ratio was measured with an electron microscope, the grating ratio was 60%, and the reflectance was measured with a spectrophotometer. The reflectance was 0.8. %, An optical element having a desired shape can be obtained.

[Optical equipment]
The optical element of the present invention can be applied to imaging devices such as cameras and video cameras, or projection devices such as liquid crystal projectors and displays, and optical scanning devices for electrophotographic devices. For example, in an optical scanning device of an electrophotographic apparatus, it is preferable to mount an fθ lens in which a plurality of protrusion-shaped protrusions (lattice portions) are formed on both the incident surface and the incident / exit surface of the fθ lens that constitutes the conjugating optical means Reflective characteristics are obtained.

[Optical scanning device]
FIG. 5 is a cross-sectional view of an essential part in the main scanning direction when an fθ lens including an optical element manufactured by any one of the manufacturing methods 1 and 2 is applied to scanning optical means of an optical scanning device such as an electrophotographic apparatus. FIG.

  Here, the main scanning direction is a direction perpendicular to the rotation axis of the deflecting means and the optical axis of the scanning optical element (the direction in which the light beam is reflected and deflected (deflected and scanned) by the deflecting means), and the sub-scanning direction is the deflecting means. The direction parallel to the rotation axis is shown. The main scanning section is a plane parallel to the main scanning direction and including the optical axis of the scanning optical means. The sub-scanning cross section indicates a cross section perpendicular to the main scanning cross section. The locus of the principal ray of the scanning light beam is called a deflection surface. In FIG. 4, the deflection surface coincides with the paper surface.

  In the figure, reference numeral 1 denotes light source means (semiconductor laser), which is composed of, for example, a single beam laser or a multi-beam laser. A collimator lens 2 converts the divergent light beam emitted from the light source means 1 into a substantially parallel light beam. Reference numeral 3 denotes an aperture stop which shapes the beam shape by limiting the passing light flux. A cylindrical lens 4 has a predetermined power only in the sub-scanning direction, and the light beam that has passed through the aperture stop 3 is substantially applied to a deflecting surface (reflection surface) 5a of an optical deflector 5 to be described later in the sub-scanning section. It is formed as a line image.

  An optical deflector 5 as a deflecting means is composed of, for example, a four-sided polygon mirror (rotating polygon mirror), and is rotated at a constant speed in the direction of arrow A in the figure by a driving means (not shown) such as a motor. ing.

  Reference numeral 6 denotes an fθ lens system as a scanning optical means having a condensing function and fθ characteristics. The first and second fθ lenses (scanning optics) manufactured by any one of the manufacturing methods 1 and 2 described above. Element) 6a, 6b, and a plurality of projection-shaped projections (lattice portions) 8 are formed on the entrance and exit surfaces 6a1, 6a2, 6b1, 6b2 of the first and second fθ lenses 6a, 6b. Thus, a light beam based on the image information reflected and deflected by the optical deflector 5 is imaged on the photosensitive drum surface 7 as the surface to be scanned, and the light deflecting surface 5a of the optical deflector 5 and the photosensitive surface in the sub-scan section. By having a conjugate relationship with the drum surface 7, it has a tilt correction function.

  Reference numeral 7 denotes a photosensitive drum surface as a surface to be scanned.

  The light beam from the light source means 1 may be directly incident on the deflecting means 5 without using the optical elements 2, 3, 4.

  Each lens surface of the first and second scanning lenses 6a and 6b in the present embodiment has a spherical or aspherical curved surface shape in the main scanning section shown in FIG. The base shape is a known special aspherical shape whose curvature changes from on-axis (scanning center) to off-axis (scanning periphery). In the present embodiment, the projection surface 6a1 and the exit surface 6a2 of the first scanning lens 6a and the entrance surface 6b1 and the exit surface 6b2 of the second lens 6b are fine projections made of a transparent resin material or glass material on the entire surface. A plurality of portions 8 are formed.

  In this embodiment, the divergent light beam emitted from the semiconductor laser 1 is converted into a substantially parallel light beam by the collimator lens 2, the light beam (light quantity) is limited by the aperture stop 3, and is incident on the cylindrical lens 4. Of the substantially parallel light beam incident on the cylindrical lens 4, the light beam is emitted as it is in the main scanning section. In the sub-scan section, the light beam converges and forms a substantially linear image (a linear image long in the main scanning direction) on the deflecting surface 5a of the optical deflector 5. Then, the light beam reflected and deflected by the deflecting surface 5a of the optical deflector 5 is imaged in a spot shape on the photosensitive drum surface 7 via the first and second fθ lenses 6a and 6b, and the optical deflector 5 is moved to an arrow. By rotating in the A direction, the photosensitive drum surface 7 is optically scanned in the arrow B direction (main scanning direction) at a constant speed. As a result, an image is recorded on the photosensitive drum surface 7 as a recording medium.

  In this embodiment, the semiconductor laser 1 serving as the light source means is arranged so that the light beam incident on the scanning optical means 6 is incident with substantially P-polarized light. That is, the semiconductor laser 1 is arranged so that the horizontal transverse mode direction is substantially parallel to the scanned surface 7.

  In this embodiment, as described above, a special aspherical shape is used as the base shape for the entire incident surface 6a1 and exit surface 6a2 of the first scanning lens 6a of the scanning optical means 6 and the incident surface 6b1 and exit surface 6b2 of the second lens 6b. And a plurality of fine projections 8 shown in FIG. 2 are formed on the surface. As a result, the reflected light at each incident / exit surface is reduced, and the aim is to suppress the variation of the transmitted light amount due to the angle of view.

  In this embodiment, a plurality of protrusions 8 may be provided on one optical surface (such as a surface having the largest incident angle) that has the greatest influence on ghost light and flare light reaching the surface to be scanned 7. In addition, a plurality of protrusions 8 may be provided on one or a plurality of optical surfaces. The surface on which the protrusion 8 is provided may be a spherical surface, an aspherical surface, a rotationally asymmetric curved surface, a diffractive surface, or a flat surface.

  The protrusion 8 is formed in a fine substantially cylindrical shape as shown in FIG. However, the cylindrical shape may be an elliptical shape even if the cross section is not a perfect circle, or a distorted circular / elliptical shape. Further, the size of the cross section does not need to be completely the same in the vicinity of the base and the tip, and for example, there is no problem even if the size of the cross-sectional shape in the vicinity of the base is about 2-3 times thicker than that in the vicinity of the front. Further, the sizes of the protrusions 8 do not need to be completely matched, and may have a difference of about 2 to 3 times.

[Image forming apparatus]
FIG. 6 is a cross-sectional view of the principal part in the sub-scanning direction showing an embodiment of the image forming apparatus of the present invention using the optical scanning device having the configuration shown in FIG. In the figure, reference numeral 104 denotes an image forming apparatus. Code data Dc is input to the image forming apparatus 104 from an external device 117 such as a personal computer. The code data Dc is converted into image data (dot data) Di by a printer controller 111 in the apparatus. The image data Di is input to the optical scanning device 100 having the configuration shown in FIG. The light scanning device 100 emits a light beam 103 modulated in accordance with the image data Di, and the light beam 103 scans the photosensitive surface of the photosensitive drum 101 in the main scanning direction.

  The photosensitive drum 101 serving as an electrostatic latent image carrier (photoconductor) is rotated clockwise by a motor 115. With this rotation, the photosensitive surface of the photosensitive drum 101 moves in the sub-scanning direction perpendicular to the main scanning direction with respect to the light beam 103. Above the photosensitive drum 101, a charging roller 102 for uniformly charging the surface of the photosensitive drum 101 is provided so as to contact the surface. The surface of the photosensitive drum 101 charged by the charging roller 102 is irradiated with a light beam 103 scanned by the optical scanning device 100.

  As described above, the light beam 103 is modulated based on the image data Di, and by irradiating the light beam 103, an electrostatic latent image is formed on the surface of the photosensitive drum 101. The electrostatic latent image is developed as a toner image by a developing unit 107 disposed so as to contact the photosensitive drum 101 further downstream in the rotation direction of the photosensitive drum 101 than the irradiation position of the light beam 103.

  The toner image developed by the developing unit 107 is transferred onto a sheet 112 as a transfer material by a transfer roller 108 disposed below the photosensitive drum 101 so as to face the photosensitive drum 101. The paper 112 is stored in the paper cassette 109 in front of the photosensitive drum 101 (on the right side in FIG. 5), but can be fed manually. A paper feed roller 110 is provided at the end of the paper cassette 109, and feeds the paper 112 in the paper cassette 109 into the transport path.

  As described above, the sheet 112 on which the unfixed toner image has been transferred is further conveyed to a fixing device behind the photosensitive drum 101 (left side in FIG. 6). The fixing device includes a fixing roller 113 having a fixing heater (not shown) therein, and a pressure roller 114 disposed so as to be in pressure contact with the fixing roller 113, and the sheet conveyed from the transfer unit. The unfixed toner image on the paper 112 is fixed by heating 112 while applying pressure at the pressure contact portion between the fixing roller 113 and the pressure roller 114. Further, a paper discharge roller 116 is disposed behind the fixing roller 113, and the fixed paper 112 is discharged out of the image forming apparatus.

  Although not shown in FIG. 6, the print controller 111 controls not only the data conversion described above, but also controls each part in the image forming apparatus including the motor 115, a polygon motor in the optical scanning apparatus described later, and the like. I do.

  When this image forming apparatus was used to repeatedly output a pattern image and a photographic image, no ghost phenomenon occurred and there was no problem in durability.

[Color image forming apparatus]
FIG. 7 is a schematic view of a main part of a color image forming apparatus of an embodiment of the present invention using a plurality of optical scanning devices having the configuration shown in FIG. This embodiment is a tandem type color image forming apparatus in which four optical scanning devices are arranged in parallel and image information is recorded on a photosensitive drum surface as an image carrier. In FIG. 7, 60 is a color image forming apparatus, 61, 62, 63, and 64 are optical scanning devices each having the structure shown in FIG. 5, 21, 22, 23, and 24 are photosensitive drums as image carriers, respectively. , 32, 33 and 34 are developing units, and 51 is a conveyor belt.

  In FIG. 7, the color image forming apparatus 60 receives R (red), G (green), and B (blue) color signals from an external device 52 such as a personal computer. These color signals are converted into C (cyan), M (magenta), Y (yellow), and B (black) image data (dot data) by a printer controller 53 in the apparatus. These image data are input to the optical scanning devices 61, 62, 63 and 64, respectively. From these optical scanning devices, light beams 41, 42, 43, and 44 modulated according to each image data are emitted, and the photosensitive surfaces of the photosensitive drums 21, 22, 23, and 24 are caused by these light beams. Scanned in the main scanning direction.

  The color image forming apparatus in this embodiment has four optical scanning devices (61, 62, 63, 64) arranged in each color of C (cyan), M (magenta), Y (yellow), and B (black). Correspondingly, image signals (image information) are recorded on the photosensitive drums 21, 22, 23, and 24 in parallel, and a color image is printed at high speed.

  As described above, the color image forming apparatus in this embodiment uses the light beams based on the respective image data by the four optical scanning devices 61, 62, 63 and 64, and the photosensitive drums 21 and 22 respectively corresponding the latent images of the respective colors. , 23, 24 on the surface. Thereafter, a single full color image is formed by multiple transfer onto a recording material.

  As the external device 52, for example, a color image reading device including a CCD sensor may be used. In this case, the color image reading apparatus and the color image forming apparatus 60 constitute a color digital copying machine.

Sectional drawing of the principal part of the optical element and metal mold | die in the shaping | molding process of Example 1 of this invention The top view of the protrusion part of the optical element taken out from the metal mold | die and metal mold | die of Example 1 of this invention The perspective view of the projection part of the optical element taken out from the metal mold | die after the shaping | molding of Example 1 of this invention Graph showing the simulation results of the lattice ratio when the pitch is 300 nm and the projection height is 160 nm Sectional drawing of the principal part of the optical scanning device carrying the optical element of this invention Cross-sectional view of essential parts of the image forming apparatus of the present invention Sectional drawing of the principal part of the color image forming apparatus of this invention

Explanation of symbols

1 Light source means (semiconductor laser)
DESCRIPTION OF SYMBOLS 2 Collimator lens 3 Aperture stop 4 Cylindrical lens 5 Optical deflector 5a Deflection surface 6 Scanning optical means 6a, 6b fθ lens 6a1, 6b1 Incident surface 6a2, 6b2 Outgoing surface 7 Scanned surface 8 Protrusion 9 Mother shape 10 Mold 11 Mold Mold hole h1 Lattice height h2 Projection height 100 Optical scanning device 101 Photosensitive drum 102 Charging roller 103 Light beam 104 Image forming device 107 Developing device 108 Transfer roller 109 Paper cassette 110 Paper feed roller 111 Printer controller 112 Transfer material (paper)
DESCRIPTION OF SYMBOLS 113 Fixing roller 114 Pressure roller 115 Motor 116 Paper discharge roller 117 External apparatus 61, 62, 63, 64 Optical scanning device 21, 22, 23, 24 Image carrier (photosensitive drum)
31, 32, 33, 34 Developer 41, 42, 43, 44 Light beam 51 Paper transport path 52 External device 53 Printer controller 60 Color image forming apparatus

Claims (6)

Using a mold in which a plurality of concave recesses are formed independently on a plane or a surface having a finite curvature independently of the normal direction of the surface, a convex microstructure lattice corresponding to the recesses on the surface In an optical element manufacturing method for manufacturing an optical element having
The depth of the concave portion of the mold is 1.5 times or more and 10 times or less the height of the design value of the convex portion of the optical element.   The optical element manufacturing method according to claim 1, wherein a design value of the grating ratio of the mold is lower than a design value of the grating ratio of the optical element.   The method of manufacturing an optical element according to claim 1, comprising a step of injection molding using the mold.   The method of manufacturing an optical element according to claim 1, wherein the mold is manufactured by anodization.   The method for manufacturing an optical element according to claim 1, wherein the mold has a shape in which a lattice ratio of the optical element is 30% to 70%.   A scanning lens manufactured using the method of manufacturing an optical element according to claim 1.