JP4737293B2 - Optical element, resin mold and optical element manufacturing method - Google Patents

Description

  The present invention relates to an optical element and a resin molding die for forming the optical element.

  Conventionally, a resin-molded plastic lens is used as an objective lens which is an optical element for an optical pickup device for recording or reproducing on an optical information recording medium such as a CD or a DVD.

  A plastic lens has a smaller specific gravity than a glass mold lens, and thus can be reduced in weight. For this reason, the load on the actuator for driving the lens can be reduced and the moment of inertia is small, so that there is an advantage that it is easy to improve the response.

  As an objective lens for an optical pickup device by such resin molding, a flange portion is provided on the outer periphery of the lens, and a mounting reference surface and a lens surface (optical functional surface) that come into contact with the lens frame or bobbin when being attached to the lens frame or bobbin. There is known a plastic lens provided with a recess between the two (for example, see Patent Document 1).

  FIG. 12 is a schematic cross-sectional view when the objective lens 30 formed by the mold described in the prior art (Patent Document 1) is attached to the lens frame 31 of the optical pickup device.

  The plastic lens disclosed in Patent Document 1 has a problem that tilting of the optical function surface with respect to the attachment reference surface occurs because the reference surface for attachment to the lens frame and the optical function surface are formed by different molds. Here, the tilt is an inclination with respect to the ideal optical axis O. Further, when the plastic lens is released from the mold, distortion occurs in the recess, and the flatness of the attachment reference surface is deteriorated, so that the lens attachment stability to the lens frame is deteriorated. As a result, there has been a problem that the initial performance and stability of coma are liable to deteriorate.

  Also, in recent years, a high-capacity pit such as a Blu-ray disc (BD) having a higher density pit than a conventional DVD and using a blue-violet laser near 400 nm and an NA of the objective lens is about 0.85. A disk and an optical pickup device using the disk have also been put into practical use. An objective lens used for recording or reproducing on a high storage capacity disk using such a blue-violet laser requires a higher NA value than an objective lens compatible with a CD or a conventional DVD.

The amount of coma generated by tilt increases as the NA value increases, and it is more important to suppress this coma in the case of an objective lens corresponding to a disk with a high storage capacity using the above-described blue-violet laser. Become.
Japanese Patent Laid-Open No. 2002-200654

  In view of the above problems, the present invention reduces the tilt of the optical function surface with respect to the mounting reference surface during molding of a plastic lens and ensures the flatness of the mounting reference surface, thereby improving the initial performance and stability of coma aberration. It is an object of the present invention to provide a mold that can be used, and an optical element having stable optical performance despite a high NA value that is molded thereby.

  Furthermore, in order to reduce the difficulty of mold processing, when the mold is divided into a central member (core) and a peripheral member (cavity) that are the nesting parts, both of them are required to incorporate the central member into the peripheral member. It is necessary to provide a gap (clearance) at the boundary between the members. For this reason, at the time of lens molding, there is a possibility that the resin enters the gap and a burr in the optical axis direction is generated on the mounting reference surface side. When attaching the lens to the bobbin or lens frame of the actuator, this burr comes into contact with the bobbin or lens frame, and the lens is tilted and attached to the lens frame. It is thought to get.

  Therefore, in view of the above problems, the present invention molds an optical element that can improve the mounting accuracy without tilting when the lens is mounted even if the mold is divided into the central member and the peripheral member, and the optical element. It is also intended to provide a mold.

  The above object is achieved by the invention described below.

1. An optical function part and a flange part around the optical function part, wherein the optical function part has an NA value of 0.7 or more, and the optical function part includes a first optical function surface and a second optical function surface facing each other. The first optical functional surface has a smaller curvature than the second optical functional surface, and the surface of the flange portion on the second optical functional surface side is separated from the optical axis. There are provided at least two steps having a height that decreases with distance from each other, and the second optical functional surface and the surface of the flange portion on the second optical functional surface side include a central member and a peripheral member. Formed by a second mold part, the two steps are a first step and a second step, and the second step is located outside the first step, The boundary between the central member and the peripheral member is positioned on the boundary between the first step and the second step. Optical element characterized by being formed by.

  2. 2. The optical element according to 1, wherein a surface on the second optical function surface side of the flange portion serves as a reference surface when mounted on a lens frame.

  3. The optical element according to 1 or 2, wherein the following conditional expression is satisfied:

0.4 <L _f1 / L _fA <1.0
However, L _f1 represents the length (mm) in the direction perpendicular to the optical axis of the surface adjacent to the second optical functional surface among the surfaces of the flange portion on the second optical functional surface side, and L _fA represents the length (mm) in the direction perpendicular to the optical axis of the entire flange portion.

  4). The surface adjacent to the second optical function surface of the flange portion is a surface having the highest height on the second optical function surface side in the flange portion. An optical element according to 1.

  5. The optical element according to any one of claims 1 to 4, wherein a plurality of concave portions or convex portions are provided on a surface of the flange portion on the first optical function surface side.

  6). The optical system according to any one of 1 to 5, wherein a height of the first optical function surface on the optical axis protrudes from a surface of the flange portion on the first optical function surface side. element.

7. Any one of 1 to 6, wherein a surface having a surface roughness Ry of 0.3 μm or less is provided on a surface orthogonal to the optical axis formed on the flange portion on the second optical function surface side. An optical element according to 1.
8). The surface adjacent to the second optical function surface of the flange portion and the surface connecting the first step are formed to be inclined with respect to the optical axis, and the first step and the second step are formed. The optical element according to any one of 1 to 7, wherein a surface to be connected is formed in parallel to the optical axis .
9. The first optical functional surface and the surface of the flange portion on the first optical functional surface side are formed by a first mold portion including a central member and a peripheral member. An optical element according to any one of the above .
10. 10. The optical element according to 9, wherein the central member of the first mold part forms both the first optical functional surface of the optical element and at least a part of the flange part .
11. The surface of the flange portion on the first optical function surface side is closer to the second optical function surface by a distance of 0.005 mm to 0.5 mm in the optical axis direction than the apex of the first optical function surface. It is located, The optical element in any one of 1-10 characterized by the above-mentioned .
12 The surface of the flange portion on the first optical function surface side has a plane portion orthogonal to the optical axis, and the surface roughness Ry of the plane portion is 0.1 μm or less. The optical element in any one .

13 . In a resin molding mold for manufacturing an optical element having an optical function section and a flange section around the optical function section, and the NA value of the optical function section is 0.7 or more, the resin molding mold is a mold A first mold part in which the optical element remains in the opened state; and a second mold part in which the optical element does not remain in the opened state, wherein the optical function part is a first optical function facing each other. And the first optical functional surface has a smaller curvature than the second optical functional surface, and the first optical functional surface is formed by the first mold part. but the second optical functional surface by said second mold portion are formed respectively, before Symbol second mold part has a centering member containing at least the optical axis and the peripheral member around the The second optical functional surface of the optical element and the frame by the central member of the second mold part. At least part of di-section are formed together, the central member is formed at least a part of the plane perpendicular to the optical axis of said flange portion, said peripheral member, the surface of the flange portion perpendicular to the optical axis The surface of the flange portion formed by molding the other part and formed by the peripheral member is positioned closer to the first optical function surface side than the surface of the flange portion formed by the center member, and the center member The portion corresponding to the flange portion has a first step, the portion corresponding to the flange portion of the peripheral member has a second step, and the second step is more than the first step. A mold for resin molding, which is located on the first optical functional surface side .
14 14. The mold for resin molding according to 13, wherein the first mold part has a projecting part that projects the flange part to release the optical element from the first mold part .

15 . 15. The mold for resin molding according to 13 or 14 , wherein the following conditional expression is satisfied.

0.4 <L _f1 / L _fA <1.0
However, L _f1 represents the length (mm) in the direction perpendicular to the optical axis of the surface adjacent to the second optical functional surface among the surfaces of the flange portion on the second optical functional surface side, and L _fA represents the length (mm) in the direction perpendicular to the optical axis of the entire flange portion.

16 . The surface adjacent to the second optical functional surface of the flange portion is a surface having the highest height on the second optical functional surface side in the flange portion . Mold for resin molding as described in 2.
17. The mold for resin molding according to any one of 13 to 16, wherein the first mold part includes a central member and peripheral members around the central member .
18. 18. The mold for resin molding according to 17, wherein the central member of the first mold part forms both the first optical functional surface of the optical element and at least a part of the flange part. .

19 . An optical element manufacturing method for manufacturing an optical element having a flange part around the optical function part and an optical element having a NA value of 0.7 or more in the optical function part using a resin molding die,
The resin molding die has a first mold part in which the optical element remains in the mold open state and a second mold part in which the optical element does not remain in the mold open state, and the optical function part is The first optical functional surface has a first optical functional surface and a second optical functional surface, and the first optical functional surface has a smaller curvature than the second optical functional surface, and the first mold part The first optical functional surface is formed by the second mold part, and the second optical functional surface is formed by the second mold part, and the second mold part includes a central member including at least the optical axis and its periphery. And at least a part of the second optical functional surface of the optical element and the flange portion are formed together by the central member of the second mold portion.
The center member is formed at least part of a surface orthogonal to the optical axis of the flange portion,
The peripheral member forms another part of the surface of the flange portion orthogonal to the optical axis, and the surface of the flange portion formed by the peripheral member is more than the surface of the flange portion formed by the central member. Located on the first optical function surface side,
A portion corresponding to the flange portion of the central member has a first step, a portion corresponding to the flange portion of the peripheral member has a second step, and the second step is the first step. Located on the first optical function surface side of the step,
And characterized by comprising the steps of: said second mold portion, and pre-adjusting the position relation of the central member and said peripheral member, fixed at a desired relative positional relationship, and a step for molding the optical element An optical element manufacturing method.

20. The first mold part has a protruding part that protrudes the flange part to release the optical element from the first mold part, and after opening the mold, the flange part of the optical element is 20. The method for manufacturing an optical element according to 19, wherein the method includes a step of protruding by a protruding portion and releasing the mold.
21. 21. The optical element manufacturing method according to 19 or 20, wherein the following conditional expression is satisfied.
0.4 <L _f1 / L _fA <1.0
However, L _f1 represents the length (mm) in the direction perpendicular to the optical axis of the surface adjacent to the second optical functional surface among the surfaces of the flange portion on the second optical functional surface side, and L _fA represents the length (mm) in the direction perpendicular to the optical axis of the entire flange portion.
22. The optical element manufacturing method according to any one of 19 to 21, wherein the first mold part includes a central member and peripheral members around the central member.
23. 23. The optical element manufacturing method according to 22, wherein the central member of the first mold part forms both the first optical functional surface of the optical element and at least a part of the flange part.

  According to the present invention, the mounting reference surface can be accurately molded, the initial performance and stability of coma aberration can be improved, the mold with reduced processing difficulty, and the stable performance molded thereby. It is possible to provide an optical element having the same (even if the NA value is high).

  Moreover, even if the mold is divided into a central member and a peripheral member, there is provided an optical element capable of improving the mounting accuracy without tilting when the lens is mounted on the lens frame, and a mold for molding the optical element. It becomes possible.

It is a side view which shows an example of the objective lens for optical pick-up apparatuses which is an optical element which concerns on this Embodiment. It is sectional drawing which shows schematic structure of the metal mold | die for resin molding for manufacturing the objective lens shown in FIG. 3 (a) and 3 (b) showing the mold opening state of the resin molding die shown in FIG. 2 and the operating state of the protruding portion. FIGS. 4A and 4B show the objective lens with the gate manufactured by the resin molding die shown in FIG. It is an expanded sectional view which shows the mold shape of a flange part periphery when a parting line is set between the thicknesses of a flange part with the metal mold | die shown in FIG. It is a side view which shows the other example of the objective lens for optical pick-up apparatuses which is an optical element which concerns on this Embodiment. It is sectional drawing which shows schematic structure of the metal mold | die for resin molding for manufacturing the objective lens shown in FIG. FIGS. 8A and 8B show the mold opening state and the protruding portion operating state of the resin molding die shown in FIG. FIGS. 9A and 9B show the objective lens with the gate manufactured by the resin molding die shown in FIG. FIG. 8 is an enlarged cross-sectional view showing the shape of the mold around the flange when the parting line is set between the thicknesses of the flange in the mold shown in FIG. 7. FIGS. 11A and 11B are schematic cross-sectional views when the objective lens molded by the resin molding die shown in FIG. 2 is attached to the lens frame of the pickup device. It is typical sectional drawing when the objective lens shape | molded with the metal mold | die described in the prior art is attached to the lens frame of the pick-up apparatus. It is an expanded sectional view which shows the mold shape of the flange part periphery of the other example of a setting of the parting line of the metal mold | die shown in FIG. It is an expanded sectional view which shows the mold shape of the flange part periphery of the other example of a setting of the parting line of the metal mold | die shown in FIG. FIGS. 15A and 15B are schematic cross-sectional views when the objective lens molded by the resin molding die shown in FIG. 7 is attached to the lens frame of the pickup device.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.

  FIG. 6 is a side view showing a first example of an objective lens for an optical pickup device that is an optical element according to the present embodiment.

  An optical pickup device objective lens 1 (hereinafter also referred to as an objective lens) shown in FIG. 6 includes an optical function surface 1a and an optical function surface 1b, which are optical function portions, and a flange portion 1f formed around the optical function surface. Have. In the following, description will be given with a circular optical functional surface and a circular flange portion, but the flange portion 1f may be partially formed or the outer shape may be rectangular. In addition, an optical path difference providing structure such as a diffractive surface having a ring-shaped step may be formed on at least one of the optical function surfaces 1a and 1b.

  In the optical pickup device, the objective lens 1 shown in FIG. 6 is preferably arranged so that the optical function surface 1b faces the optical disc side and the optical function surface 1a faces the light source side. In the present embodiment, the optical functional surface 1b facing the optical disc corresponds to the first optical functional surface, and the optical functional surface 1a facing the light source corresponds to the second optical functional surface.

  As shown in FIG. 6, the second optical functional surface (optical functional surface 1a) has a larger curvature than the first optical functional surface (optical functional surface 1b) facing the optical disc side, and the effective diameter is the second. The optical functional surface (optical functional surface 1a) is preferably larger than the first optical functional surface (optical functional surface 1b). The effective diameter of the second optical function surface is preferably 0.3 mm or more and 7 mm or less, and more preferably 0.5 mm or more and 4 mm or less.

Further, as shown, the flange portion 1f, the most second optical functional surface (optical functional surface 1a) flange surface is a plane perpendicular to the optical axis O on the side 1f _0, further outside the flange surface 1f _0, A first step 1f ₁ having a step on the optical disc side is formed. This first step is preferably provided concentrically around the optical axis when the objective lens is viewed from the optical axis direction.

  FIGS. 15A and 15B are schematic cross-sectional views when the objective lens 1 shown in FIG. 6 is attached to the lens frame of the pickup device. FIG. 15A shows the whole, and FIG. 15B is an enlarged view showing the periphery of the flange portion 1f.

As shown in FIG. 15 (a), the objective lens 1 is fixed by abutting the flange surface 1f ₀ of the flange portion 1f in the lens frame 31. That is, the flange surface 1f ₀ formed by the mold 12 is a central member of the place depicted in cross-sectional view of a resin molding die shown in FIG. 7, a reference surface when mounting the lens barrel. Further, the first step 1f ₁ is not in contact with the lens frame 31 with a gap.

The width A in the radial direction of the flange surface 1f ₀ is mounting reference surface shown in FIG. 15 (b) is more preferably preferably 0.20~0.50mm about about 0.10～0.80Mm. Width B of the first radial direction of the step 1f ₁ is preferably about 0.01～0.20Mm, about 0.05~0.15mm is more preferable. Further, the step amount D in the optical axis direction of the first step 1f ₁ with respect to the flange surface 1f ₀ is preferably about 0.005 to 0.20 mm within a range not exceeding the thickness of the flange surface 1f0 in the optical axis direction. If it is 0.02-0.06 mm, it is more preferable. Optical axis direction of the thickness of the flange surface 1f ₀ is preferably about 0.2～1.50Mm, more preferably 0.2～1.00Mm. Further, it is preferable that the surface of connecting flange surface 1f ₀ and the first step 1f ₁ are formed in parallel to the optical axis.

Further, it is preferable to have a partial flange surface 1f ₀ is the surface roughness Ry on the side of the portion close to at least the optical axis formed by the mold 12 is at least the central member is 0.3μm or less. The flange surface 1f ₁ may have a surface roughness Ry of 0.3 μm or less, but this need not be the case. More preferably, it has a portion having a surface roughness Ry of 0.1 μm or less. The surface roughness Ry is the height from the lowest valley bottom to the highest mountain peak in the minute irregularities of the surface. Further, the surface or taper surface in the same direction as the optical axis between the steps may have a surface roughness Ry of 0.3 μm or more.

  Although described again, FIG. 7 is a cross-sectional view showing a schematic configuration of a resin molding die for manufacturing the objective lens 1 shown in FIG.

  In the resin mold shown in FIG. 7, the first mold part is composed of the mold 11 and the second mold part is composed of the mold 12 and the mold 14 with the parting line PL as a boundary. ing. The mold 11 as the first mold part corresponds to the movable side, and the mold 12 and the mold 14 as the second mold part correspond to the fixed side mold.

  A shape 11 b for forming the optical function surface 1 b of the objective lens 1 is formed on the mold 11. Furthermore, the protrusion part 13 is provided in the location of the flange part 1f of the objective lens 1, for example in four places on the periphery. The protruding portion 13 is movable relative to the mold 11 toward the flange portion 1f. The protruding portion 13 and the mold portion 11 are fitted with a clearance of a diameter of 0.001 to 0.06 mm. Further, as shown in the drawing, the protruding portion 13 and the mold portion 11 are located inside the mold portion 11. A large gap is formed between them.

The mold 12 constitutes a nesting part with respect to the mold 14. The mold 12 includes a shape 12a for forming an optical functional surface 1a (second optical functional surface) that is an optical functional surface having a larger effective diameter among the optical functional portions of the objective lens 1, and a first portion of the flange portion 1f. among the surfaces of the second optical functional surface side to form a flange surface 1f ₀ is mounting reference surface. Further, the mold 14, forming a step 1f _1. That is, the boundary of the mold 12 and the mold 14 is a flange surface 1f ₀ and the boundary line of the step 1f ₁ is a mounting reference surface. Further, without forming the recess between the second optical functional surface side surface of the flange surface 1f ₀ is the reference plane mounting an optically functional surface 1a (second optical functional surface), was connected to each of the extension It is formed into a shape. In other words, the surface 1f ₀ adjacent to the second optical functional surface 1a of the flange portion 1f is the highest on the second optical functional surface side of the flange portion 1f (1f ₀ , 1f ₁ ). It is preferably formed on a high surface. Here, “the height of 1f ₀ is high” means that the position on the second optical function surface side is high in the optical axis direction, and the position on the first optical function surface side is low. That's it. That is, it is preferable that the flange portion does not have a shape as shown in FIG. In addition, the shape which connected each extension line said in this specification is not restricted only to the above, The rounding (R) which touches each extension line in the vicinity of the intersection of each extension line The shape connected with is also included.

  Moreover, about the flange surface, it is preferable to satisfy | fill the following conditional expressions as another parameter | index.

0.4 <L _f1 / L _fA <1.0
L _f1 is the length (mm) in the direction perpendicular to the optical axis of the surface 1f ₀ adjacent to the second optical functional surface, out of the surfaces 1f ₀ and 1f ₁ on the second optical functional surface side of the flange portion. L _fA represents the length (mm) in the direction perpendicular to the optical axis of the entire flange portion 1f (a combination of 1f ₀ and 1f ₁ ). In other words, L _f1 is the length of the roller A in FIG. 15B, and L _fA is the length of A + B in the roller of FIG. 15B.

By making the value of L _f1 / L _fA smaller than the upper limit value of the above conditional expression, it is possible to provide at least one step on the surface of the flange portion on the second optical function surface side. Meanwhile, with the terms of processing the portion corresponding to the surface 1f ₀ on the mold 12 but it is preferable the value of L _{f1 /} L _fA is smaller, to reduce the tilt of the optical functional surface with respect to the mounting reference surface, the mounting reference In order to ensure the flatness of the surface, it is preferable to make the value of L _f1 / L _fA larger than the lower limit value of the conditional expression.

More preferably, the following conditional expression is satisfied.
0.6 <L _f1 / L _fA <1.0
It is even more preferable that the following conditional expression is satisfied.

0.6 <L _f1 / L _fA <0.9
In the mold 12 as the central member, the second optical functional surface and the surface on the second optical functional surface side of the flange portion are integrally formed, so that the flange portion that is the reference mounting surface of the objective lens is formed. There is no room for deviation in the positional relationship between the second optical functional surface side and the second optical functional surface (optical functional surface 1a), and the second optical functional surface (optical functional surface 1a) is not relative to the attachment reference surface. The position can be accurately formed, and an objective lens for an optical pickup device having stable performance can be obtained.

  Further, the mold 12 is configured to be capable of fine adjustment of the position in the thickness direction of the objective lens with respect to the mold 14 and is fixed after fine adjustment of the position in the thickness direction is performed.

  The parting line PL is set at a position where the depth of the flange portion 1 f of the mold 11 is deeper than the depth of the flange portion of the mold 14. Further, 1 g is a gate from which a molten resin material is injected.

  8 (a) and 8 (b) are views showing the mold opening state and the operating state of the protruding portion of the resin molding die shown in FIG. FIG. 8A shows the mold opening state, and FIG. 8B shows the operating state of the protruding portion.

  Hereafter, the manufacturing process of the objective lens 1 is demonstrated using FIG.7 and FIG.8 (a), 8 (b).

  In the state shown in FIG. 7, a molten resin material is poured from the gate 1g. At this time, the gas inside the mold flows out from the clearance formed in the protruding portion 13 and the mold portion 11. With regard to the degassing inside the mold, a mold internal sealing mechanism using an air suction device such as a vacuum pump and an O-ring is provided and sucked before the molten resin material flows into the mold. The method of deaeration in the air, the method of performing deaeration by sucking while the molten resin material flows into the mold, the suction starts before the molten resin material flows into the mold, and the inflow It is more preferable to use a method of performing deaeration by performing suction. By doing so, the transfer property to the objective lens 1 having a mold shape is further improved, and the optical function surface 1a with higher accuracy is obtained. 1b can be formed.

  Next, as shown in FIG. 8A, the mold 11 moves so as to be separated from the mold 12 and the mold 14. At this time, the objective lens 1 remains in the mold 11 side.

  Thereafter, as shown in FIG. 8 (b), the projecting portion 13 arranged at a position corresponding to the flange portion 1f is projected from the mold 11 in the direction of the arrow to release the objective lens 1 to thereby release the gate. The objective lens 1 is attached with 1 g. The protrusions 13 are provided at a plurality of locations, and even if the operations of the protrusions 13 are the same or different, the difference in the protrusion timing is within 0.5 seconds so that all protrusions are completed. It is preferable to prevent the objective lens 1 from being deformed. The mold 11 corresponds to the first mold part, and the mold 12 and the mold 14 correspond to the second mold part.

  FIGS. 9A and 9B are diagrams showing the objective lens 1 manufactured with the resin molding die shown in FIG. 7 and having a gate 1g. FIG. 9A is a plan view of the objective lens 1 viewed from the protruding portion side, and FIG. 9B is a side view.

  FIG. 9A shows a case where the protruding portions are arranged at four positions indicated by 13n on the flange portion 1f at intervals of approximately 90 degrees. The protruding portion trace by the protruding portion serves as an index for discriminating between the optical function surfaces 1a and 1b when the optical head portion is subsequently assembled into the optical head portion, and has the effect of making the incorporation easier.

  Although the protruding portion trace by this protruding portion is preferably a concave portion, it may be a convex portion. In this case, the flange portion has a plurality of convex portions. Moreover, it is preferable that a recessed part or a convex part is circular as shown to Fig.9 (a) and 9 (b). Furthermore, the number of protrusions, that is, the number of recesses or protrusions is preferably about 2 to 4 from the viewpoint of releasing while maintaining good moldability.

  As shown in FIG. 9B, the surface on the side where the protruding portion of the flange portion 1f abuts is d = 0 .0 within a range not exceeding the thickness of the flange portion 1f from the position on the optical axis of the optical function surface 1b. It is desirable that it is located on the optical function surface 1a side by 005 mm to 0.5 mm, and more preferably, it is located on the optical function surface 1a side by d = 0.02 mm to 0.12 mm. By adopting such a shape, it becomes easy to form the surface roughness Ry of at least a part of the surface on the flange portion 1 f to be 0.1 μm or less, and this objective lens 1 is incorporated into the optical pickup device. For the adjustment, it becomes possible to use a portion having a surface roughness Ry of 0.1 μm or less. Further, even when a burr due to the fitting clearance between the protruding portion 13 and the mold portion 11 in FIG. 7 occurs in the protruding portion trace, the working is also performed when the objective lens is incorporated in the optical pickup device because of the above-described step d. The distance will not be shortened.

Furthermore, the surface with which the protruding portion abuts is the optical function surface side of the D ₁ side having the smaller effective diameter, that is, the optical function surface 1b (first optical surface) of the two optical function surfaces having the effective diameters D ₁ and D _2. It is desirable to be provided in the flange portion on the functional surface side. By doing in this way, a protrusion part can be formed large, keeping the objective lens external shape containing the flange part 1f small.

  The objective lens 1 is completed by removing the gate 1g from the objective lens 1 with the gate 1g shown in FIGS. 9 (a) and 9 (b).

  FIG. 10 is an enlarged cross-sectional view showing the mold shape around the flange portion 1f when the parting line PL is set between the thicknesses of the flange portion 1f in the mold shown in FIG.

Fig As shown in 10, the boundary of the parting line PL, the protrusion 13 is towards the mold 11 side of the depth and t ₁ of, t ₂ the other mold 14 and the mold 12 side depth In this case, t ₁ > t ₂ is preferable. Furthermore, when the angle of the taper taper on the side of the mold 11 having the protruding portion 13 is α and the angle of the taper taper on the other mold 12 and mold 14 side is β, α ≦ β may be satisfied. preferable. Further, the range of α is preferably 0 ° ≦ α ≦ 3 °. By forming the mold parts 11, 12, and 14 in this way, the objective lens is not brought to the molds 12 and 14 side when the mold is opened, and the mold 11 having the protrusions is surely provided. Can be left to the side.

Moreover, it is preferable to form a plane part orthogonal to the optical axis on the surface of the flange part 1f on the first optical function surface side. In particular, as in the example shown in FIG. 14, it is preferable to form a planar portion 1 k perpendicular to the optical axis in a part near the optical axis on the surface of the flange portion 1 f on the first optical functional surface side. Preferably, it is preferable to form a flat portion 1k orthogonal to the optical axis just outside the end of the first optical function surface. In addition, it is preferable that the surface roughness Ry of the said plane part 1k is 0.1 micrometer or less. Moreover, it is preferable that the width W (direction orthogonal to the optical axis) of the flat portion 1k is 0.1 mm or more and 0.5 mm or less. More preferably, it is 0.2 mm or more and 0.4 mm or less. By irradiating the plane portion 1k with parallel light and using the reflected light, it is possible to detect an inclination or the like when the objective lens 1 is attached to the lens frame. Note that, by setting t ₁ > t ₂ , the force that the objective lens 1 is brought to the mold part 12 at the time of mold opening becomes small, so that there is also an effect that the flat part is hardly distorted. .

  Further, as shown in FIG. 14, the mold on the first optical functional surface 1b side is formed by the central member 15 forming the first optical functional surface 1b and the above-described flat portion 1k, and the periphery forming the periphery thereof. You may divide | segment into a member. As a result, there is a merit that the processing difficulty of the mold is reduced.

  Further, the boundary between the mold 12 and the mold 14 is preferably parallel to the optical axis, and by forming in this way, the mold 12 and the mold 14 are fitted with a very small gap (clearance). It is possible to suppress the generation of burrs.

  Next, a second example of the optical pickup objective lens according to the present embodiment will be described. This example shows an example in which even if burrs are generated due to the clearance between the mold 12 and the mold 14, tilting does not occur during lens mounting, and mounting accuracy can be improved.

  FIG. 1 is a side view showing a second example of an objective lens for an optical pickup device that is an optical element according to the present embodiment.

  An optical pickup device objective lens 1 (hereinafter also referred to as an objective lens) shown in FIG. 1 includes an optical function surface 1a and an optical function surface 1b, which are optical function portions, and a flange portion 1f formed around the optical function surface. Have. In the following, description will be given with a circular optical functional surface and a circular flange portion, but the flange portion 1f may be partially formed or the outer shape may be rectangular. In addition, an optical path difference providing structure such as a diffractive surface having a ring-shaped step may be formed on at least one of the optical function surfaces 1a and 1b.

  In the optical pickup device, the objective lens 1 shown in FIG. 1 is preferably arranged so that the optical function surface 1b faces the optical disc side and the optical function surface 1a faces the light source side. In the present embodiment, the optical functional surface 1b facing the optical disc corresponds to the first optical functional surface, and the optical functional surface 1a facing the light source corresponds to the second optical functional surface.

  As shown in FIG. 1, the second optical functional surface (optical functional surface 1a) has a larger curvature than the first optical functional surface (optical functional surface 1b) facing the optical disc, and the effective diameter is the second. The optical functional surface (optical functional surface 1a) is preferably larger than the first optical functional surface (optical functional surface 1b). The effective diameter of the second optical function surface is preferably 0.3 mm or more and 7 mm or less, and more preferably 0.5 mm or more and 4 mm or less.

Further, as shown, the flange portion 1f, the most second optical functional surface (optical functional surface 1a) flange surface is a plane perpendicular to the optical axis O on the side 1f _0, further outside the flange surface 1f _0, A first step 1f ₁ and a second step 1f ₂ having a step on the optical disc side are formed. The first step and the second step are preferably provided concentrically around the optical axis when the objective lens is viewed from the optical axis direction.

  11A and 11B are schematic cross-sectional views when the objective lens 1 shown in FIG. 1 is attached to the lens frame of the pickup device. FIG. 11A shows the whole, and FIG. 11B is an enlarged view showing the periphery of the flange portion 1f.

As shown in FIG. 11 (a), the objective lens 1 is fixed by abutting the flange surface 1f ₀ of the flange portion 1f in the lens frame 31. That is, the flange surface 1f ₀ formed by the mold 12 is a central member of the place depicted in cross-sectional view of a resin molding die shown in FIG. 2, a reference surface when mounting the lens barrel. Further, the first step 1f ₁ is not in contact with the lens frame 31 with a gap.

The width A in the radial direction of the flange surface 1f ₀ is mounting reference surface shown in FIG. 11 (b) is more preferably preferably 0.20~0.50mm about about 0.10～0.80Mm. The radial width B ′ of the first step 1f ₁ is preferably about 0.01 to 0.25 mm, more preferably about 0.08 to 0.15 mm. Width C of the second radial step 1f ₂ is preferably about 0.01～0.20Mm, about 0.05~0.15mm is more preferable. Furthermore, the first step 1f ₁ relative to the flange surface 1f ₀ optical axis direction of the step amount D and step amount of the second stepped 1f ₂ optical axis directions with the first reference a step 1f ₁ E Is preferably about 0.005 to 0.20 mm within a range not exceeding the thickness of the flange surface 1f _{0 in} the optical axis direction, and more preferably 0.02 to 0.06 mm. Optical axis direction of the thickness of the flange surface 1f ₀ is preferably about 0.20～1.50Mm, more preferably 0.20～1.00Mm. Further, the surface connecting the flange surface 1f ₀ and the first step 1f ₁ is preferably formed with a taper in the range of 1 ° to 60 ° when viewed in a cross-sectional view, and the first step 1f ₁ And the second step 1f ₂ are preferably formed in parallel to the optical axis.

The flange surface 1f ₀ preferably has a portion where the side portions on the surface roughness Ry of at least close to the optical axis is 0.3μm or less. The flange surface 1f ₁ may have a surface roughness Ry of 0.3 μm or less, but this need not be the case. More preferably, it has a portion having a surface roughness Ry of 0.1 μm or less. The surface roughness Ry is the height from the lowest valley bottom to the highest mountain peak in the minute irregularities of the surface. Further, the second step 1f ₂ may have a surface roughness Ry of 0.3 μm or more. Further, the surface or taper surface in the same direction as the optical axis between the steps may have a surface roughness Ry of 0.3 μm or more.

  FIG. 2 is a sectional view showing a schematic configuration of a resin molding die for manufacturing the objective lens 1 shown in FIG.

  In addition, in the following figures, in order to avoid duplication of description, the same functional member will be given the same reference numeral.

  In the resin molding die shown in FIG. 2, the first mold part is composed of the mold 11 with the parting line PL as a boundary, and the second mold part is composed of the mold 12 and the mold 14. ing. The mold 11 as the first mold part corresponds to the movable side, and the mold 12 and the mold 14 as the second mold part correspond to the fixed side mold.

  A shape 11 b for forming the optical function surface 1 b of the objective lens 1 is formed on the mold 11. Furthermore, the protrusion part 13 is provided in the location of the flange part 1f of the objective lens 1, for example in four places on the periphery. The protruding portion 13 is movable relative to the mold 11 toward the flange portion 1f. The protruding portion 13 and the mold portion 11 are fitted with a clearance of a diameter of 0.001 to 0.06 mm. Further, as shown in the drawing, the protruding portion 13 and the mold portion 11 are located inside the mold portion 11. A large gap is formed between them.

The mold 12 constitutes a nesting part with respect to the mold 14. The mold 12 includes a shape 12a for forming an optical functional surface 1a (second optical functional surface) that is an optical functional surface having a larger effective diameter among the optical functional portions of the objective lens 1, and a first portion of the flange portion 1f. Of the two optical function surface sides, the flange reference surface 1f ₀ and the first step 1f ₁ are formed. Further, the mold 14 forms a _second step 1f2. That is, the boundary of the mold 12 and the mold 14 is a first step 1f ₁ and the second boundary line of the step 1f _2. Further, without forming the recess between the second optical functional surface side surface of the flange surface 1f ₀ is the reference plane mounting an optically functional surface 1a (second optical functional surface), was connected to each of the extension It is formed into a shape. In other words, the surface 1f ₀ adjacent to the second optical functional surface 1a of the flange portion 1f is the most on the second optical functional surface side of the flange portion 1f (1f ₀ , 1f ₁ , 1f ₂ ). It is preferably formed on a high surface. That is, it is preferable that the flange portion is not shaped as shown in FIG. Here, “the height of 1f ₀ is high” means that the position on the second optical function surface side is high in the optical axis direction, and the position on the first optical function surface side is low. That's it. In addition, the shape connecting the respective extension lines as referred to in the present specification is not limited to the above, and rounded corners (R) that touch each extension line in the vicinity of the intersection of the respective extension lines. The shape connected with is also included.

  Moreover, about the flange surface, it is preferable to satisfy | fill the following conditional expressions as another parameter | index.

0.4 <L _f1 / L _fA <1.0
L _f1 is the length in the direction orthogonal to the optical axis of the surface 1f ₀ adjacent to the second optical functional surface among the surfaces 1f ₀ , 1f ₁ , 1f ₂ on the second optical functional surface side of the flange portion ( mm), and L _fA represents the length (mm) in the direction perpendicular to the optical axis of the entire flange portion 1f (1f ₀ , 1f ₁ , 1f ₂ combined). In other words, L _f1 is the length of the roller A in FIG. 11B, and L _fA is the length of A + B + C in the roller of FIG. 11B.

By making the value of L _f1 / L _fA smaller than the upper limit value of the conditional expression, it is possible to provide at least two steps on the surface of the flange portion on the second optical function surface side. Meanwhile, with the terms of processing the portion corresponding to the surface 1f ₀ on the mold 12 but it is preferable the value of L _{f1 /} L _fA is smaller, to reduce the tilt of the optical functional surface with respect to the mounting reference surface, the mounting reference In order to ensure the flatness of the surface, it is preferable to make the value of L _f1 / L _fA larger than the lower limit value of the conditional expression.

  More preferably, the following conditional expression is satisfied.

0.6 <L _f1 / L _fA <1.0
It is even more preferable that the following conditional expression is satisfied.
0.6 <L _f1 / L _fA <0.9
In the mold 12 as the central member, the second optical functional surface and the surface on the second optical functional surface side of the flange portion are integrally formed, so that the flange portion that is the reference mounting surface of the objective lens is formed. There is no room for deviation in the positional relationship between the second optical functional surface side and the second optical functional surface (optical functional surface 1a), and the second optical functional surface (optical functional surface 1a) is not relative to the attachment reference surface. The position can be accurately formed, and an objective lens for an optical pickup device having stable performance can be obtained.

  Further, the mold 12 is configured to be capable of fine adjustment of the position in the thickness direction of the objective lens with respect to the mold 14 and is fixed after fine adjustment of the position in the thickness direction is performed.

  The parting line PL is set at a position where the depth of the flange portion 1 f of the mold 11 is deeper than the depth of the flange portion of the mold 14. Further, 1 g is a gate from which a molten resin material is injected.

  FIGS. 3A and 3B are views showing the mold opening state and the operating state of the protruding portion of the resin molding die shown in FIG. FIG. 3A shows the mold open state, and FIG. 3B shows the operating state of the protruding portion.

  Hereafter, the manufacturing process of the objective lens 1 is demonstrated using FIG.2 and FIG.3 (a), 3 (b).

  In the state shown in FIG. 2, a molten resin material is poured from the gate 1g. At this time, the gas inside the mold flows out from the clearance formed in the protruding portion 13 and the mold portion 11. With regard to the degassing inside the mold, a mold internal sealing mechanism using an air suction device such as a vacuum pump and an O-ring is provided and sucked before the molten resin material flows into the mold. The method of deaeration in the air, the method of performing deaeration by sucking while the molten resin material flows into the mold, the suction starts before the molten resin material flows into the mold, and the inflow It is more preferable to use a method of performing deaeration by performing suction. By doing so, the transfer property to the objective lens 1 having a mold shape is further improved, and the optical function surface 1a with higher accuracy is obtained. 1b can be formed.

  Next, as shown in FIG. 3A, the mold 11 moves so as to be separated from the mold 12 and the mold 14. At this time, the objective lens 1 remains in the mold 11 side.

  Thereafter, as shown in FIG. 3 (b), the projecting portion 13 disposed at a position corresponding to the flange portion 1f is projected from the mold 11 in the direction of the arrow to release the objective lens 1 to thereby release the gate. The objective lens 1 is attached with 1 g. The protrusions 13 are provided at a plurality of locations, and even if the operations of the protrusions 13 are the same or different, the difference in the protrusion timing is within 0.5 seconds so that all protrusions are completed. It is preferable to prevent the objective lens 1 from being deformed. The mold 11 corresponds to the first mold part, and the mold 12 and the mold 14 correspond to the second mold part.

  4 (a) and 4 (b) are views showing the objective lens 1 with the gate 1g manufactured by the resin molding die shown in FIG. 4A is a plan view of the objective lens 1 viewed from the protruding portion side, and FIG. 4B is a side view.

  FIG. 4A shows a case where the protruding portions are arranged at four positions indicated by 13n on the flange portion 1f at intervals of approximately 90 degrees. The protruding portion trace by the protruding portion serves as an index for discriminating between the optical function surfaces 1a and 1b when the optical head portion is subsequently assembled into the optical head portion, and has the effect of making the incorporation easier.

  Although the protruding portion trace by this protruding portion is preferably a concave portion, it may be a convex portion. In this case, the flange portion has a plurality of convex portions. Moreover, it is preferable that a recessed part or a convex part is circular as shown to Fig.4 (a) and 4 (b). Furthermore, the number of protrusions, that is, the number of recesses or protrusions is preferably about 2 to 4 from the viewpoint of releasing while maintaining good moldability.

  As shown in FIG. 4B, the surface on the side where the protruding portion of the flange portion 1f abuts is d = 0 .0 within a range not exceeding the thickness of the flange portion 1f from the position on the optical axis of the optical function surface 1b. It is desirable that it is positioned on the optical function surface 1a side by 005 mm to 0.5 mm, and more preferably d = 0.02 mm to 0.12 mm. By adopting such a shape, it becomes easy to form the surface roughness Ry of at least a part of the surface on the flange portion 1 f to be 0.1 μm or less, and adjustment when the objective lens 1 is incorporated in the optical pickup device. In addition, a portion having a surface roughness Ry of 0.1 μm or less can be used. Further, even if burrs occur on the protruding portion trace due to the fitting clearance between the protruding portion 13 and the mold portion 11 in FIG. 2, there is a difference in level d, so that the working is performed even when the objective lens is incorporated in the optical pickup device. The distance will not be shortened.

Furthermore, the surface with which the protruding portion abuts is the optical function surface side of the D ₁ side having the smaller effective diameter, that is, the optical function surface 1b (first optical surface) of the two optical function surfaces having the effective diameters D ₁ and D _2. It is desirable to be provided in the flange portion on the functional surface side. By doing in this way, a protrusion part can be formed large, keeping the objective lens external shape containing the flange part 1f small.

  The objective lens 1 is completed by removing the gate 1g from the objective lens 1 with the gate 1g shown in FIGS. 4 (a) and 4 (b).

  FIG. 5 is an enlarged cross-sectional view showing the mold shape around the flange portion 1f when the parting line PL is set between the thicknesses of the flange portion 1f in the mold shown in FIG.

As shown in FIG. 5, with the parting line PL as a boundary, the depth on the mold 11 side where the protruding portion 13 exists is t _1, and the depth on the other mold 14 and mold 12 side is t _2. In this case, t ₁ > t ₂ is preferable. Furthermore, it is preferable that α ≦ β, where α is the draft taper angle on the side of the mold 11 with the protruding portion 13 and β is the draft taper angle on the other mold 14 side. Moreover, when the angle of the taper taper of the mold 12 is γ, it is preferable that α ≦ γ. Further, the range of α is preferably 0 ° ≦ α ≦ 3 °. Note that, as in the example shown in FIG. 13, the parting line may be set at the position of the second step and α = 0 °. By forming the mold parts 11, 12, and 14 in this way, the objective lens is not brought to the molds 12 and 14 side when the mold is opened, and the mold 11 having the protrusions is surely provided. Can be left to the side.

  In addition, it is preferable to form a plane portion orthogonal to the optical axis on the surface of the flange portion 1f on the first optical function surface side. In particular, as in the example shown in FIG. 13, it is preferable to form a planar portion 1 k perpendicular to the optical axis in a part of the portion near the optical axis on the surface of the flange portion 1 f on the first optical function surface side. Preferably, it is preferable to form a flat portion 1k orthogonal to the optical axis just outside the end of the first optical function surface. The surface roughness Ry of the flat portion 1k is preferably 0.1 μm or less. In addition, it is preferable that the length of the width | variety W (direction orthogonal to an optical axis) of this plane part 1k is 0.1 mm or more and 0.5 mm or less. More preferably, it is 0.2 mm or more and 0.4 mm or less. The flat surface 1k is irradiated with parallel light, and the reflected light can be used to detect an inclination or the like when the lens 1 is attached to the lens frame. In addition, by setting t1> t2, since the force that the objective lens is brought to the mold part 12 side when the mold is opened is reduced, there is also an effect that the flat part is hardly distorted.

  Further, as shown in FIG. 13, the mold on the first optical functional surface side is formed with the central member 15 forming the first optical functional surface 1b and the above-described flat portion 1k, and the periphery thereof. It may be divided into peripheral members 11.

  Further, the boundary between the mold 12 and the mold 14 is preferably parallel to the optical axis, and by forming in this way, the mold 12 and the mold 14 are fitted with a very small gap (clearance). It is possible to suppress the generation of burrs. In addition, even if it occurs, there is a step, so that the attachment reference plane is not affected during attachment to the lens frame.

  As described above, by protruding a part of the flange portion formed on the outer periphery of the optical function surface when releasing the objective lens from the first mold portion on the movable side, the first die It is not necessary to move the mold for forming the first optical functional surface on the part 11 side for releasing the mold, so that the tilt amount and the shift amount of the mold for forming the first optical functional surface are different for each shot. It will not happen. Here, the shift is a displacement in the direction perpendicular to the ideal optical axis O of the mold. Further, the mold 12 and the mold 14 which are the second mold parts are divided into two molds, but the mounting reference surface and the optical function surface are integrally formed on the same mold 12. Therefore, the tilt amount of the second optical function surface (optical function surface 1a) with respect to the surface on the second optical function surface side of the flange portion, which is a reference surface for attaching the objective lens 1 to the lens frame, is different for each shot. This is no longer the case. For this reason, it is possible to obtain a resin molding die from which an objective lens for an optical pickup device having stable performance can be obtained.

  In addition, by performing deaeration using the clearance of the protruding portion, there is no need to separately form a deaeration portion, and a good optical function surface can be formed. Furthermore, the accuracy of the protruding portion may be relatively loose, and does not affect the formation of the optical function surface.

  Further, as described in the second embodiment, in the case of a form having a flange portion having two steps, even if burrs are generated due to the clearance between the mold 12 and the mold 14, the lens Tilt does not occur during installation, and the installation accuracy can be improved. Thereby, compared with the first embodiment, the mold of the second embodiment can be somewhat easier to mold because the clearance between the mold 12 and the mold 14 can be somewhat widened. There is an effect.

  In the objective lens shown in the present embodiment, the two optical function surfaces do not cause misalignment, and the position of the optical function surface from the attachment reference surface is stable. When applied to an objective lens used for recording or reproduction on a high storage capacity disk using a blue-violet laser with a wavelength of about 0.9 to about 400 nm, the effect is even greater.

  When the objective lens shown in the present embodiment is a compatible lens for recording / reproducing a plurality of optical discs, the NA value is the NA value of the optical disc having the highest NA among the optical discs applied for recording or reproduction. . For example, when the optical element according to the present invention is used as a compatible lens for BD and HD DVD, the NA value is about 0.85 which is the NA value of BD, and is used as a compatible lens for BD, DVD, and CD. In this case, the NA value is about 0.85 which is the NA value of BD.

Claims (23)

An optical function part and a flange part around the optical function part, wherein the optical function part has an NA value of 0.7 or more, and the optical function part includes a first optical function surface and a second optical function surface facing each other. The first optical functional surface has a smaller curvature than the second optical functional surface, and the surface of the flange portion on the second optical functional surface side is separated from the optical axis. There are at least two steps that decrease in height as you move away .
The second optical functional surface and the surface of the flange portion on the second optical functional surface side are formed by a second mold portion including a central member and a peripheral member,
The two steps include a first step and a second step, and the second step is located outside the first step, and the first step and the second step An optical element , wherein a boundary between the central member and the peripheral member is located on a boundary between steps . 2. The optical element according to claim 1 , wherein a surface on the second optical function surface side of the flange portion serves as a reference surface when mounted on a lens frame. The optical element according to claim 1 or 2, characterized in that the following conditional expression is satisfied.
0.4 <L _f1 / L _fA <1.0
However, L _f1 represents the length (mm) in the direction perpendicular to the optical axis of the surface adjacent to the second optical functional surface among the surfaces of the flange portion on the second optical functional surface side, and L _fA represents the length (mm) in the direction perpendicular to the optical axis of the entire flange portion. The second optical functional surface and the adjacent surface of the flange portion, of claim 1 to 3, characterized in that the the most high high surface in the second optical function surface of the flange portion The optical element according to any one of the above. The surface of the first optical functional surface side of the flange portion, the optical element according to any one of claims 1-4, wherein a plurality of recesses or protrusions are provided. The height of the optical axis of the first optical functional surface is any one of claims 1 to 5, characterized in that protrudes from the surface of the first optical functional surface side of the flange portion An optical element according to 1. Said second plane perpendicular to the flange portion and the optical axis formed of the optical functional surface, the surface roughness Ry of claims 1-6, characterized in that it has a portion serving as 0.3μm or less The optical element according to any one of the above. The surface adjacent to the second optical function surface of the flange portion and the surface connecting the first step are formed to be inclined with respect to the optical axis, and the first step and the second step are formed. The optical element according to claim 1, wherein the connecting surface is formed in parallel with the optical axis . 2. The first optical functional surface and a surface of the flange portion on the first optical functional surface side are formed by a first mold portion including a central member and a peripheral member. The optical element of any one of -8 . The optical element according to claim 9, wherein the central member of the first mold part forms both the first optical functional surface of the optical element and at least a part of the flange part . The surface of the flange portion on the first optical function surface side is closer to the second optical function surface by a distance of 0.005 mm to 0.5 mm in the optical axis direction than the apex of the first optical function surface. It is located, The optical element of any one of Claims 1-10 characterized by the above-mentioned . The surface of the flange portion on the first optical function surface side has a plane portion orthogonal to the optical axis, and the surface roughness Ry of the plane portion is 0.1 μm or less. 11. The optical element according to any one of 11 above . In a resin molding mold for manufacturing an optical element having an optical function section and a flange section around the optical function section, and the NA value of the optical function section is 0.7 or more, the resin molding mold is a mold A first mold part in which the optical element remains in the opened state; and a second mold part in which the optical element does not remain in the opened state, wherein the optical function part is a first optical function facing each other. And the first optical functional surface has a smaller curvature than the second optical functional surface, and the first optical functional surface is formed by the first mold part. However, each of the second optical functional surfaces is formed by the second mold part, and the second mold part has a central member including at least an optical axis and a peripheral member around the central member. The central member of the second mold part causes the second optical functional surface of the optical element and the frame to be flat. At least part of di-section are formed together,
The center member is formed at least part of a surface orthogonal to the optical axis of the flange portion,
The peripheral member forms another part of the surface of the flange portion orthogonal to the optical axis, and the surface of the flange portion formed by the peripheral member is more than the surface of the flange portion formed by the central member. Located on the first optical function surface side,
A portion corresponding to the flange portion of the central member has a first step, a portion corresponding to the flange portion of the peripheral member has a second step, and the second step is the first step. tree butter mold shall be the being located in the first optical function surface than the step. The mold for resin molding according to claim 13, wherein the first mold part has a protruding part that protrudes the flange part to release the optical element from the first mold part. . The resin molding die according to claim 13 or 14, wherein the following conditional expression is satisfied .
0.4 <L _f1 / L _fA <1.0
However, L _f1 represents the length (mm) in the direction perpendicular to the optical axis of the surface adjacent to the second optical functional surface among the surfaces of the flange portion on the second optical functional surface side, and L _fA represents the length (mm) in the direction perpendicular to the optical axis of the entire flange portion. The surface adjacent to the second optical functional surface of the flange portion is a surface having the highest height on the second optical functional surface side in the flange portion. The mold for resin molding according to any one of the above . The mold for resin molding according to any one of claims 13 to 16, wherein the first mold part includes a center member and peripheral members around the center member . 18. The resin molding according to claim 17, wherein the central member of the first mold part forms both the first optical functional surface of the optical element and at least a part of the flange part. Mold. An optical element manufacturing method for manufacturing an optical element having a flange part around the optical function part and an optical element having a NA value of 0.7 or more in the optical function part using a resin molding die,
The resin molding die has a first mold part in which the optical element remains in the mold open state and a second mold part in which the optical element does not remain in the mold open state, and the optical function part is The first optical functional surface has a first optical functional surface and a second optical functional surface, and the first optical functional surface has a smaller curvature than the second optical functional surface, and the first mold part The first optical functional surface is formed by the second mold part, and the second optical functional surface is formed by the second mold part, and the second mold part includes a central member including at least the optical axis and its periphery. And at least a part of the second optical functional surface of the optical element and the flange portion are formed together by the central member of the second mold portion.
The center member is formed at least part of a surface orthogonal to the optical axis of the flange portion,
The peripheral member forms another part of the surface of the flange portion orthogonal to the optical axis, and the surface of the flange portion formed by the peripheral member is more than the surface of the flange portion formed by the central member. Located on the first optical function surface side,
A portion corresponding to the flange portion of the central member has a first step, a portion corresponding to the flange portion of the peripheral member has a second step, and the second step is the first step. Located on the first optical function surface side of the step,
The step of adjusting the positional relationship between the central member and the peripheral member of the second mold part in advance and fixing it in a desired relative positional relationship, and the step of molding the optical element, An optical element manufacturing method . The first mold part has a protruding part that protrudes the flange part to release the optical element from the first mold part, and after opening the mold, the flange part of the optical element is 20. The method of manufacturing an optical element according to claim 19, further comprising a step of projecting and releasing from the projecting portion . The optical element manufacturing method according to claim 19, wherein the following conditional expression is satisfied .
0.4 <L _f1 / L _fA <1.0
However, L _f1 represents the length (mm) in the direction perpendicular to the optical axis of the surface adjacent to the second optical functional surface among the surfaces of the flange portion on the second optical functional surface side, and L _fA represents the length (mm) in the direction perpendicular to the optical axis of the entire flange portion. The optical element manufacturing method according to any one of claims 19 to 21, wherein the first mold part includes a central member and peripheral members around the central member. 23. The optical element manufacturing according to claim 22, wherein the central member of the first mold part forms both the first optical functional surface of the optical element and at least a part of the flange part. Method.