JP2005193646A - Optical element and mold for molding optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a difficulty in obtaining a satisfied bonding strength for fixing an optical element with a small diameter and thin thickness to a holder and in keeping an optical characteristics under a high-temperature environment in a lens, a prism or a mirror used for an optical instrument. <P>SOLUTION: The optical element 1 has an optically functional face 1a, 1b and the outer peripheral part 1c used for fixing the optical element 1 and by making a surface roughness of at least one of the face of the outer peripheral part 1c larger than the roughness of the optically functional face 1a, 1b, the surface area and the bonding strength are increased and also a heat radiating cooling effect is improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-precision optical element such as a lens, a prism, and a mirror used in an optical apparatus and an optical element molding die for molding the optical element.

  In general, an optical element used for recording / reproduction of an optical information signal is molded by heating, kneading and melting resin pellets and injection-filling them into a cavity of a mold as disclosed in, for example, Patent Document 1. As disclosed in Patent Document 2, it is molded by a compression molding method in which a plastic material pre-processed into a substantially final shape is supplied into a mold and then heated and pressurized.

  Hereinafter, a conventional method for molding an optical element will be described with reference to the drawings. 7A and 7B are schematic views of an optical element formed by a conventional compression molding method. FIG. 7A is a schematic top view, and FIG. 7B is a schematic side view. FIG. 8 is a schematic cross-sectional view of the mold for the conventional optical element.

  In these drawings, 40 is an optical element, 40a and 40b are optical functional surfaces having the optical function of the optical element 40, and 40c is an outer peripheral edge portion integrally formed in a bowl shape on the outer peripheral portion of the optical functional surfaces 40a and 40b. The outer peripheral edge 40c is used for fixing the optical element 40 to the holder. 41 is an upper mold, 42 is a lower mold, 43 is a trunk mold, 41a and 42a are optical function surface molding parts for molding the optical function surfaces 40a and 40b of the optical element 40 formed on the upper mold 41 and the lower mold 42, respectively. 43a is an outer peripheral edge forming portion for forming the outer peripheral edge portion 40c of the optical element 40 constituted by the upper die 41, the lower die 42 and the body die 43, and 44 is a press having a heating and pressing mechanism for the upper die 41. A head 45 is a press stage having a heating mechanism for the lower die 42.

The optical element 40 is molded by first using an optical material (polycarbonate) pre-processed into a final shape by injection molding or the like in a cavity formed by an upper mold 41, a lower mold 42, and a body mold 43 (in a molding mold). To supply. Thereafter, the upper die 41, the lower die 42, and the barrel die 43 are heated to desired temperatures near the glass transition point by the heating mechanism of the press head 44 and the press stage 45. When the optical material and the upper die 41, the lower die 42, and the barrel die 43 reach a desired temperature (for example, a glass transition temperature +15 to 40 ° C.), the press head 44 is lowered, and the upper die 41 is applied to the optical material. A pressure of 10 kgf / cm ² is applied to maintain the deformation, and cooling is performed until the temperature is below the deflection temperature under load. Thereafter, the upper mold 41 is removed and the molded optical material, that is, the optical element 40 is taken out.

In the optical element 40 molded as described above, the optical function surfaces 40a and 40b are transferred by the optical function surface molding portions 41a and 42a of the upper mold 41 and the lower mold 42 which are optical element molding dies, and the upper mold The outer peripheral edge portion 40 c is formed by the outer peripheral edge portion forming portion 43 a constituted by the lower mold 42, the lower mold 42, and the body mold 43.
JP-A-61-233520 JP-A-8-127077

  However, the conventional optical element is finished so that the surface roughness of the outer peripheral edge is substantially the same as that of the optical functional surface.

  Optical elements used for pickups such as digital video discs (DVDs) and Blu-ray discs (BDs) are becoming smaller, thinner, lighter, denser, and diversified in shape. For example, the outer diameter is required to be 5 mm or less and the thickness of the outer peripheral edge is less than 1.0 mm. Therefore, the area of the adhesive surface between the holder for holding the optical element and the outer peripheral edge of the optical element is very small, and the surface of the outer peripheral edge is molded to a surface roughness close to a mirror surface. It is extremely difficult to obtain sufficient adhesive strength, fixing to the holder becomes extremely difficult, and the productivity of the pickup is remarkably reduced, and stable adhesive fixing is always difficult, which is a cause of a decrease in yield.

  Also, the heat generated by the optical element due to the laser beam becomes very large, and in the optical element using a plastic material, the optical characteristics greatly change due to a temperature change and becomes practically unstable or cannot be used depending on the optical device. A state arises.

  In addition, in an optical element used for an imaging device in a small device such as a digital still camera or a mobile phone, a part of the light beam that has passed through the optical function surface is reflected on the inner surface of the outer peripheral edge portion and becomes stray light. In order to prevent it from entering and adversely affecting the optical characteristics, black coating is applied to the outer peripheral edge.

  An object of the present invention is to provide an optical element and an optical element molding die that can secure good optical characteristics and can reliably fix the optical element and can eliminate black paint.

  The present invention provides an optical element in which a molding material is supplied into a molding die of a molding apparatus, and an optical functional surface and an outer peripheral edge having a larger outer diameter than the optical functional surface are integrally molded. By a molding die in which the surface roughness of at least one surface of the outer peripheral portion molding portion of the molding die for molding the peripheral portion is larger than the surface roughness of the optical functional surface molding portion of the molding die for molding the optical functional surface of the optical element The optical element is characterized in that the surface roughness of at least one surface of the outer peripheral edge is formed to be larger than the surface roughness of the optical functional surface.

  Further, the present invention is an optical element characterized in that the surface roughness Ra of at least one surface of the outer peripheral edge is 0.1 μm or more.

  In the optical element according to the present invention, the surface roughness Ra of the optical functional surface is 0.03 μm or less, and the surface roughness Ra of at least one surface of the outer peripheral edge is 0.1 μm or more. It is.

  Further, the present invention is an optical element characterized in that one surface having a surface roughness Ra of 0.1 μm or more is an outer diameter side surface portion of an outer peripheral edge portion.

  Further, the present invention is an optical element characterized in that the molding material is made of a resin material, the outer diameter φ of the optical element is 5 mm or less, and the thickness of the outer diameter side surface part constituting the outer peripheral edge is less than 1.0 mm. It is.

  The present invention also provides an optical element molding die for molding an optical element from a molding material supplied into a molding die, comprising an optical functional surface molding part and an outer peripheral edge part for molding an optical functional surface on the optical element. An optical element molding die having an outer peripheral edge molding part to be molded, wherein the surface roughness of at least one surface of the outer peripheral edge molding part is larger than the surface roughness of the optical functional surface molding part .

  Further, the present invention is characterized in that one surface of the outer peripheral edge molding portion having a surface roughness larger than the surface roughness of the optical function surface molding portion is an outer diameter side surface molding portion of the outer peripheral edge molding portion. This is an optical element molding die.

  As described above, in the optical element of the present invention, the surface roughness of at least one surface of the outer peripheral edge is larger (rougher) than the surface roughness of the optical functional surface, so that the surface roughness of the outer peripheral edge is optical. Since the surface area of the outer peripheral edge used for fixing the optical element to the holder is increased compared to the functional surface having the same surface roughness, the fixed area such as adhesion is reduced even in a small and thin optical element. As a result, the fixing strength with the holder is increased, and a stable holding state can be obtained.

  Further, since the surface area of the outer peripheral edge of the optical element is increased, the effect of heat dissipation and cooling is also increased, and the effect of stabilizing the operation of the optical device at a high temperature can be obtained.

  Then, increasing the surface roughness of at least one surface of the outer peripheral edge portion of the optical element means that the surface roughness of at least one surface of the outer peripheral edge molding portion of the mold is the surface of the optical functional surface molding portion. By making it larger than the roughness, it can be easily and accurately molded simultaneously with the molding of the optical element.

  Furthermore, by increasing the surface roughness of the outer peripheral edge, there is almost no reflection of light at the outer peripheral edge, and there is no adverse effect such as stray light even if the outer peripheral edge is not smeared in the subsequent process. Therefore, the productivity of the optical element can be improved and the cost can be reduced.

  Hereinafter, embodiments of the present invention will be described.

(Example 1)
1A and 1B are schematic views of an optical element according to Example 1 of the present invention, in which FIG. 1A is a schematic top view, FIG. 1B is a schematic side view, and FIG. 2 is a molding of the optical element of Example 1. It is a schematic sectional drawing of an apparatus.

  1 is an optical element, 1a and 1b are optical functional surfaces having the optical function of the optical element 1, and 1c is an outer diameter of the optical functional surfaces 1a and 1b integrally formed on the outer peripheral portion of the optical functional surfaces 1a and 1b. The outer peripheral edge portion 1d having a large outer diameter is an outer diameter side surface portion of the outer peripheral edge portion 1c, and the outer peripheral edge portion 1c is used for fixing the optical element 1 to the holder. 2 is an upper mold, 3 is a lower mold, 4 is a body mold, 2a and 3a are optical function surface molding portions for molding the optical function surfaces 1a and 1b of the optical element 1 formed on the upper mold 2 and the lower mold 3. Reference numeral 4a denotes an outer peripheral edge molding having an inner diameter larger than the inner diameter of the optical function surface molding parts 2a and 3a for molding the outer peripheral edge 1c of the optical element 1 constituted by the upper mold 2, the lower mold 3 and the body mold 4. 4d is an outer diameter side surface forming portion of the inner peripheral portion of the body mold 4 for forming the outer diameter side surface portion 1d of the outer peripheral edge portion 1c of the optical element 1, and 5 is a press having a heating and pressing mechanism for the upper die 2. A head 6 is a press stage having a heating mechanism for the lower mold 3.

  Here, the optical function surface is a surface including an optical action surface necessary for producing the optical characteristics required for the optical element 1, and is a surface that becomes a path of light rays.

  In Example 1, the surface roughness of each part of the optical element 1 shown in FIG. 1, that is, the surface roughness of the optical functional surfaces 1a and 1b of the optical element is different from the surface roughness of the outer diameter side surface part 1d. For this reason, in the molding die of the optical element 1, the surface roughness of the outer-diameter side surface molding portion 4d is made different from the surface roughness of the optical function surface molding portions 2a and 3a of the upper die 2 and the lower die 3. .

  Next, the optical element of Example 1 and its molding apparatus will be specifically described.

  As a molding material for the optical element, an amorphous polyolefin resin (manufactured by Nippon Zeon Co., Ltd., trade name ZEONEEX, glass transition point Tg = 150 ° C., heat distortion temperature Tt = 125 ° C.) was used.

  First, a molding material (not shown) of the optical element 1 is supplied into a molding die composed of an upper die 2, a lower die 3, and a barrel die 4, and this molding die is arranged between the press head 5 and the press stage 6. To do. As the molding material, a polyolefin resin (glass transition point Tg = 140 ° C., deflection temperature under load Tt = 123 ° C.) molded into an approximate shape of the optical element 1 by injection molding was used.

  The upper mold 2, the lower mold 3, and the body mold 4 constituting the mold are made of cemented carbide, and the optical function surface molding portions 2a and 3a are processed into desired shapes so as to obtain an optical function. It is. The upper mold 2, the lower mold 3, and the body mold 4 may be made of other materials as long as they can be used for molding other than the above-described materials. For example, as the material of the upper die 2 and the lower die 3, the optical functional surface molding portions 2a and 3a may be formed by using, for example, electroless nickel plating on the surface of stainless steel (STAVAX) as a base material. However, when the strength is considered, it is preferable to use a cemented carbide as a base material. In addition, a protective film or the like may be applied to the surface of the molding surface in order to improve mold release properties and prevent mold oxidation and corrosion.

  The molding material placed in the mold is heated by the press head 5 and the press stage 6 to a predetermined temperature of 170 ° C. for 5 minutes. When the molding material reaches a predetermined temperature, the press head 5 is lowered at a desired speed of 0.1 mm / sec, and the molding material is deformed via the upper mold 2. When the body mold 4 and the upper mold 2 come into contact with each other, the descent, that is, pressurization is stopped. After maintaining in this state for 2 minutes at a predetermined temperature, the press head 5 is cooled down to a deflection temperature under load of 123 ° C. in 7 minutes. Then, the pressing by the press head 5 is released, the upper mold 2 is opened, and the molded optical element 1 is taken out.

  The schematic shape of the optical element 1 molded as described above is such that the curvature radius R1 of one optical functional surface 1a is 1.25 mm, the curvature radius R2 of the other optical functional surface 1b is 4.18 mm, and the center thickness t = 0.98 mm, outer diameter (diameter of outer peripheral edge portion) = 3.5 mm, and thickness of outer diameter side surface portion = 0.29 mm.

  In Example 1, in order to make the surface roughness of the outer diameter side surface portion 1d of the optical element 1 larger than the surface roughness of the optical function surfaces 1a and 1b, the surface roughness of the optical function surface molding portions 2a and 3a of the mold is increased. The surface roughness of the outer diameter side surface molding portion 4d is formed to be rougher (larger) than the surface roughness.

  Here, with reference to Table 1, verification of an optical element in which the surface roughness of the optical functional surfaces 1a and 1b and the surface roughness of the outer-diameter side surface portion 1d are variously changed will be described. As the surface roughness Ra of the optical functional surfaces 1a and 1b (both are the same roughness) Ra, five types of 0.001 μm to 0.05 μm are used, and as the surface roughness Ra of the outer diameter side surface portion 1d, 0.001 μm to An optical element in which 8 types of 0.5 μm were combined was molded. For optical elements that require high-precision optical characteristics, such as optical elements for digital video discs (DVD) and Blu-ray discs (BD), the surface roughness of the optical functional surfaces 1a and 1b is preferably 0.03 μm or less. It was confirmed by this verification that sufficient optical characteristics cannot be obtained with a surface roughness of .05 μm.

  The optical element 1 shown in Table 1 was adhered to the optical element holding holder with an adhesive with at least the outer diameter side surface portion 1d, and the adhesive strength was evaluated. An ultraviolet curable resin was used as the adhesive. As an evaluation of the adhesive strength, a peeling test is performed by attaching an adhesive tape and then removing it, that is, repeating this operation alternately for a predetermined time and a predetermined number of times in a low temperature (−20 ° C.) environment and a high temperature (90 ° C.) environment. Tests such as heat cycle were conducted.

  Table 1 shows the experimental evaluation results of the adhesive strength of each optical element 1. In the table, ◯ indicates that the desired adhesive strength is sufficiently obtained and good, and X indicates that it is insufficient.

  From Table 1, it can be seen that sufficient adhesive strength can be obtained if the surface roughness Ra of the outer-diameter side surface portion 1d is 0.1 μm or more.

  In addition, as a result of confirming the adhesive strength in the same manner as described above, the optical material obtained by molding a molding material with a glass material having the same size and the same surface roughness as described above was obtained. When the surface roughness Ra of the outer diameter side surface portion 1d is 0.1 μm or more, good adhesive strength is obtained.

  Here, the optical element 1 used for the verification described above has a surface roughness of the optical function surface molding parts 2a and 3a and the outer diameter side surface molding part 4d in the molding die for molding the optical element 1 having the above-described dimensions. The optical function surfaces 1a and 1b and the outer diameter side surface portion 1d of the verification optical element 1 are prepared to have substantially the same surface roughness as the surface roughness, and each optical element 1 is molded with these molds. It has been verified. Accordingly, in the mold, the surface roughness Ra of the outer diameter side surface molding portion 4d is made larger than the surface roughness of the optical function surface molding portions 2a and 3a, and the surface roughness Ra of the outer diameter side surface portion 1d is 0.1 μm. If it is above, the optical element 1 with sufficient adhesive strength can be shape | molded.

(Example 2)
Next, Example 2 will be described with reference to FIG. FIG. 3A is a schematic top view of the optical element, and FIG. 3B is a schematic side view thereof. In this figure, the same components as those of the optical element of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and only different points from the first embodiment will be described.

  The optical element 1 includes an outer diameter side surface portion 1d, an outer diameter side surface portion 1d1 having a surface roughness Ra of 0.1 μm or more, and a surface roughness other than the surface roughness, for example, the same surface as the optical functional surfaces 1a and 1b. The outer diameter side surface portion 1d2 having roughness is formed. This is obtained by roughening the surface roughness of only the outer-diameter side surface portion 1d1, which is the main bonding portion for fixing the optical element 1.

  And also in the shaping | molding of this optical element 1, the shaping | molding apparatus shown in FIG. 2 is used as the example, The surface roughness of only the outer diameter side surface molding part of the shaping | molding die which shape | molds the outer diameter side part 1d1 of the optical element 1 is carried out. The optical function surface molding portions 2a and 3a and the outer diameter side surface portion 1d2 are formed to be rougher than the surface roughness of the surfaces to be molded. In this example, the outer diameter side surface portion 1d1 of the optical element 1 is molded. The surface roughness Ra of the outer diameter side surface molding portion is formed to be 0.1 μm or more.

(Example 3)
Next, verification from the optical characteristic surface of the optical element will be described. The optical element of Example 3 is an optical element in which the optical function surfaces 1a and 1b and the outer peripheral edge 1c having an outer diameter larger than that of the optical function surface are integrally formed in the same manner as the optical element 1 in Example 1. Since the molding can be performed by the molding apparatus shown in FIG. 2, the description will be made with reference to FIGS. In the optical element 1 according to Example 3, the optical functional surfaces 1a and 1b have a surface roughness Ra of 0.03 μm, the outer diameter φ is 1 to 8 mm, and the surface roughness Ra of the entire outer diameter side surface portion 1d. A sample in which the thickness of the outer side surface portion 1d was changed to 0.1 to 1.6 mm was molded by the same resin material and molding apparatus as in Example 1, that is, each It is formed using a forming die formed to have a dimensional shape and surface roughness corresponding to the sample value. These optical elements 1 are fixed to a holder with an adhesive made of an ultraviolet curable resin on the outer diameter side surface 1d in the same manner as in Example 1, and mounted on an optical device to optically operate in a high temperature environment (90 ° C.). The characteristics were evaluated. In addition, the evaluation of the optical characteristics was performed by the transmitted wavefront.

  Table 2 shows the results of optical characteristics of the optical element 1 of these samples under the above high temperature environment. In the table, ◯ indicates that the usable optical characteristics are maintained even at high temperatures, and x indicates that the optical characteristics are greatly deteriorated due to high temperatures and cannot be used.

  From Table 2 above, an optical element that has conventionally been unusable due to deterioration of optical characteristics under a high temperature environment when the surface roughness Ra of the outer diameter side surface portion 1d is 0.05 μm or less, for example, outer diameter An optical element having a φ of 3 mm and an outer diameter side surface portion of 0.3 mm has a surface roughness Ra of 0.1 μm or more on the outer diameter side surface portion 1d, thereby increasing the adhesive force with the adhesive. It has been found that the heat dissipation effect is increased and the optical characteristics that can be used even in a high temperature environment are maintained. Further, when the outer diameter φ is 5 mm or more and the thickness of the outer diameter side surface portion 1d is 1.0 mm or more, the optical characteristics that can be used even if the surface roughness Ra of the outer diameter side surface portion 1d is 0.1 μm or less. It was found to maintain. If the surface roughness Ra of the outer diameter side surface portion 1d is 0.1 μm or more, all the optical elements of this sample maintain optical characteristics that can be used even at high temperatures.

  As described above, even in the case of an optical element having a particularly small diameter, the heat radiation effect of the optical element 1 itself is increased by making the surface roughness of at least the outer diameter side surface portion 1d greater than the surface roughness of the optical functional surface. This is because the temperature does not rise to a high temperature at which it cannot be used, and the optical characteristics that can be used in a high temperature environment are maintained.

  The verification of the optical element 1 by the above samples is performed when the surface roughness Ra of the optical function surfaces 1a and 1b is 0.03 μm. The surface roughness Ra of the optical function surfaces 1a and 1b is 0.02 μm and Set to 0.01 μm, the outer diameter φ and the surface roughness of the entire surface of the outer diameter side surface portion 1d, and the thickness of the outer diameter side surface portion 1d were set to the same values as described above, that is, the values shown in Table 2. Each sample optical element is molded, and these are fixed to the holder with an adhesive made of an ultraviolet curable resin in the same manner as described above, and these are mounted on an optical device to evaluate optical characteristics in a high temperature environment (90 ° C.). As a result, the same optical characteristic results as in Table 2 were obtained. This is because when the surface roughness Ra of the optical function surfaces 1a and 1b is 0.03 μm or less, the outer diameter φ is 5 mm or less, the outer diameter side surface portion 1d constituting the outer peripheral edge portion 1c is less than 1.0 mm, and the outer diameter It has been found that the optical element 1 in which the surface roughness Ra of the side surface portion 1d is larger than the surface roughness Ra of the optical functional surfaces 1a and 1b can be sufficiently used at least in a high temperature environment.

  In general, the molding resin material of this type of optical element has a small change in physical properties (for example, refractive index) due to temperature change, unlike glass materials. As described above, at least the surface roughness of the outer-diameter side surface portion 1d increases the heat dissipation effect of the optical element molded in step 1 and becomes usable. Therefore, although an optical device equipped with a recording mechanism with a high laser power generates a large amount of heat, it is effective as an optical element that can withstand it.

  Similarly, when an imaging optical element (not shown) used for a mobile phone camera was molded and the evaluation of the optical characteristics under adhesive strength and high temperature was confirmed, the same effect as described above was obtained. It was. Furthermore, the stray light required as the optical characteristics of the imaging system does not occur when the surface roughness Ra of the outer diameter side surface portion is 0.1 μm or more, and a blacking process in the subsequent process, which has been conventionally applied as a countermeasure against stray light, is also necessary. It was also possible to confirm the effect of disappearing.

  In the present invention, an optical element satisfying that the surface roughness Ra of the outer diameter side surface portion is 0.1 μm or more based on the experimental results described above has a small outer diameter (the outer diameter φ is 5 mm or less, Even if it is an optical element having a thickness of less than 1.0 mm, sufficient adhesive strength can be obtained by increasing the surface area due to irregularities on the outer diameter side surface, and even in use in severe high temperature environments The heat dissipation effect is increased and good optical characteristics are maintained. Thereby, it is possible to provide an optical element that can realize the reduction in diameter and thickness of the optical device, high functionality, and high speed.

  In the above-described embodiment, the optical element is molded using heat and pressure and compression molding. However, the present invention is not limited to this. For example, when the molding material is a resin material, the injection is more productive. You may shape | mold the optical element by the shaping | molding method in the thing similar to what was hung up in each said Example.

Example 4
FIG. 4 shows an optical element 1 molded by an injection molding method. 4A is a schematic top view of the optical element, and FIG. 4B is a schematic side view. In FIG. 4, the same components as those of the optical element 1 of the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted. In the optical element 1 molded by the injection molding method, a gate (shown by an imaginary line 1e in FIG. 4) is molded in order to injection-fill the molding material. After the molding is completed, the gate 1e is removed from the outer diameter side surface portion 1d of the optical element 1 by a method such as cutting. The gate removal trace 1f remains in a part of the outer diameter side surface portion 1d as a trace of the removal of the gate and polishing of the removed portion. Thus, the optical element 1 obtained by injection molding can obtain the same adhesive strength and heat dissipation effect as described above if the surface roughness Ra of the outer diameter side surface portion 1d other than the gate removal trace 1f is 0.1 μm or more. .

  FIG. 5 is a schematic cross-sectional view of a molding die of the optical element 1 according to the fourth embodiment. The molding die includes a movable die 10, a fixed die 11, and a body die 12. The movable die 10 and the fixed die 11 are optically connected. Optical function surface molding portions 10a and 11a for molding the optical function surfaces 1a and 1b of the element 1 are formed. Further, an outer peripheral edge forming portion 12a for forming the outer peripheral edge portion 1c of the optical element 1 is formed by the movable die 10, the fixed die 11, and the barrel die 12, and the barrel die 12 is provided in the forming die. A gate portion 13 for injecting resin is formed.

  Then, the surface roughness Ra of the outer diameter side surface forming portion 12b of the body mold 12 for forming the outer diameter side surface portion 1d of the optical element 1 is formed to be 0.1 μm or more, and this roughness is the movable die 10 and the fixed die 11. The surface roughness of the optical function surface molding portions 10a, 11a, for example, the roughness Ra is 0.03 μm or less.

  FIG. 6 is a schematic cross-sectional view of a molding apparatus for molding the optical element 1 shown in FIG. 4 by an injection molding method using the molding die shown in FIG.

  In FIG. 6, 14 is a hopper, 15 is a resin molding material made of resin pellets, 16 is an injection cylinder, 17 is a heating cylinder, 18 is a screw, 19 is a nozzle, 20 is a fixed die plate, 21 is a moving die plate, and 22 is a moving die plate. The clamping cylinder, 23 is a fixed molding table, and 24 is a movable molding table. The fixed mold 11 and the body mold 12 constituting the molding mold are fixed to the fixed molding table 23 side, and the movable mold 10 is the movable molding table 24 side. It is fixed to. In this example, a plurality of optical elements are simultaneously molded by a plurality of molds. Reference numeral 25 denotes a sprue, and 26 denotes a runner portion connected to the gate portion 13.

  First, the resin molding material 15 is put into the hopper 14, and the molding material 15 moves in the direction of the nozzle 19 as the screw 18 rotates. The resin molding material 15 is heated and kneaded and melted by the screw 18 and the heating cylinder 17, passes through the sprue 25, the runner portion 26, and the gate portion 13 from the nozzle 19 and is inserted into the fixed molding table 23 and the movable molding table 24. It is injected into a mold and filled. Since the mold is set at a predetermined temperature, for example, near the deflection temperature under load of the resin molding material 15, the optical function surface molding portions of the movable mold 10 and the fixed mold 11 are transferred, and the movable mold 10 and the fixed mold 11 are transferred. The optical element 1 having the outer peripheral edge is molded by the body mold 13. Then, after this is cooled, the movable molding table 24 is retracted by the clamping cylinder 22 to open the molding die, the molded product is taken out, gate removal and polishing are performed, and the optical element 1 shown in FIG. 4B is obtained. .

  As described above, the optical element 1 having the outer side surface portion 1d having a larger surface roughness than the surface roughness of the optical functional surfaces 1a and 1b can be obtained by injection molding of the resin, and the optical functional surfaces 1a and 1b. By changing the surface roughness of the optical function surface molding portions 10a and 11a of the movable die 10 and the fixed die 11, the surface roughness of the outer side surface portion 1d is changed to the outer side surface molding of the barrel die 12. By changing the surface roughness of the portion 12b, the optical element 1 having a desired surface roughness can be molded.

  In each of the above embodiments, at the outer peripheral edge of the optical element, the two flat portions (two surfaces orthogonal to the optical axis) are formed to have the same surface roughness as the optical functional surface, and the outer diameter Although the surface roughness of the side surface portion is larger than the surface roughness of the optical functional surface, this is a case where the main fixing surface used for fixing the optical element to the holder is the outer diameter side surface portion, When both or one of the two flat portions (two surfaces orthogonal to the optical axis) of the outer peripheral edge is a main fixing surface, at least the surface roughness of the main fixing surface is an optical functional surface in accordance with the gist of the present invention. Obviously, it is clear that the main fixing surface is not specified by the shape of the holder or the like, and all the surface roughnesses constituting the outer peripheral edge are increased in accordance with the gist of the present invention. What is necessary is just to form. Then, the selection of the surface that makes the surface roughness of the outer peripheral edge portion of the optical element rougher than the surface roughness of the optical functional surface in this way is made by selecting the molding surface of the mold, for example, two flat surfaces of the outer peripheral edge portion. When making the surface roughness of the surface more rough than the surface roughness of the optical function surface, the surface roughness of the molding surface of the upper mold, lower mold, movable mold, and fixed mold that molds the flat portion of the outer peripheral edge is optical function. What is necessary is just to make it rougher than the surface roughness of a surface molding part, and it can select easily as needed.

  The optical element of the present invention described above, that is, the configuration in which the surface roughness of at least one surface of the outer peripheral edge of the optical element is larger than the surface roughness of the optical function surface is the optical function surface molding portion of the mold By setting at least one surface roughness of the outer peripheral edge molding part, it is possible to easily and accurately mold the optical element simultaneously with the molding of the optical element.

  According to the present invention, the surface roughness of at least one surface of the outer peripheral edge portion of the optical element is made larger than the surface roughness of the optical functional surface, thereby increasing the surface area of the outer peripheral edge portion and holding the optical element and the optical element. Therefore, it is useful as a small-diameter, thin-walled optical element that can withstand heat-resistant use due to high functionality and high speed of optical equipment.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic of the optical element in Example 1 of this invention, (a) is a schematic top view, (b) is a schematic side view 1 is a schematic cross-sectional view showing an optical element molding apparatus in Embodiment 1 of the present invention. It is the schematic of the optical element in Example 2 of this invention, (a) is a schematic top view, (b) is a schematic side view It is the schematic of the optical element in Example 4 of this invention, (a) is a schematic top view, (b) is a schematic side view Schematic sectional view of an optical element molding die in Example 4 of the present invention Schematic sectional view showing an optical element molding apparatus in Example 4 of the present invention. It is the schematic of the conventional optical element, (a) is a schematic top view, (b) is a schematic side view Schematic cross-sectional view showing a conventional optical element molding apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical element 1a, 1b Optical function surface 1c Outer peripheral edge part 1d Outer diameter side surface part 1f Gate removal trace 2 Upper mold | type 2a, 3a, 10a, 11a Optical functional surface shaping | molding part 3 Lower mold | type 4 trunk | die 4a, 12a Outer peripheral edge part shaping | molding Part 4d, 12b Outer diameter side surface molding part 10 Movable type 11 Fixed type 12 Body type

Claims (7)

An optical element in which a molding material is supplied into a molding die of a molding apparatus and an optical functional surface and an outer peripheral portion having an outer diameter larger than the optical functional surface are integrally molded, and the outer peripheral portion of the optical element is molded The outer peripheral edge portion is formed by a molding die in which the surface roughness of at least one surface of the outer peripheral edge molding portion of the molding die is larger than the surface roughness of the optical functional surface molding portion of the molding die for molding the optical functional surface of the optical element. An optical element, wherein the surface roughness of at least one of the surfaces is formed to be larger than the surface roughness of the optical functional surface. 2. The optical element according to claim 1, wherein a surface roughness Ra of at least one surface of the outer peripheral edge is 0.1 μm or more. 2. The optical element according to claim 1, wherein a surface roughness Ra of the optical functional surface is 0.03 [mu] m or less, and a surface roughness Ra of at least one surface of the outer peripheral edge is 0.1 [mu] m or more. . 4. The optical element according to claim 2, wherein the one surface having a surface roughness Ra of 0.1 μm or more is an outer-diameter side surface portion of the outer peripheral edge portion. 2. The optical element according to claim 1, wherein the molding material is made of a resin material, the outer diameter φ of the optical element is 5 mm or less, and the thickness of the outer diameter side surface part constituting the outer peripheral edge part is less than 1.0 mm. . An optical element molding die for molding an optical element from a molding material supplied into a molding die, an optical functional surface molding part for molding an optical functional surface on the optical element and an outer peripheral edge molding for molding an outer peripheral edge part An optical element molding die characterized in that the surface roughness of at least one surface of the outer peripheral edge molding part is larger than the surface roughness of the optical function surface molding part. The one surface of the outer peripheral part molding part whose surface roughness is larger than the surface roughness of the optical function surface molding part is an outer diameter side molding part of the outer peripheral part molding part. Optical element mold.

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