Optical element molding dies

Abstract

The mold for optical element molding is provided with: an upper mold equipped with a neck; an upper surface molding surface provided on the neck of the upper mold, the upper surface molding surface molding the upper surface of an optical element; a lower mold equipped with a neck; a lower surface molding surface provided on the neck of the lower mold, the lower surface molding surface molding the lower surface of the optical element; a side mold into which the necks of the upper mold and lower mold are inserted; and a sleeve for housing the upper mold and the lower mold. The size relationship between a first clearance showing the clearance of a hole in the side mold and the neck of the lower mold and a second clearance showing the clearance of a hole in the side mold and the neck of the upper mold is decided according to the size relationship between a first distance showing the distance between the center of curvature of the lower surface molding surface and the outer diameter height of the optical element and a second distance showing the distance between the center of curvature of the upper surface molding surface and the outer diameter height of the optical element.

Description

[Technical field]

[0001] The present invention relates to a mold for molding optical elements. [Background technology]

[0002] In molding optical elements made of glass, a processing method has been proposed in which the outer diameter portion of the optical element is molded in addition to the upper and lower optical surfaces, eliminating the need for centering after molding (eg, Patent Document 1).

[0003] In the method proposed in Patent Document 1, in order to make the upper and lower dies coaxial, a sleeve that holds the dies has an inner circumference formed in a straight line (without steps), and the side dies that mold the outer diameter part of the optical element are constructed separately from the upper and lower dies. The side dies are positioned by fitting with the sleeve, and a clearance (gap) is provided between the inner circumference of the side dies and the necks of the upper and lower dies. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4549820 Summary of the Invention [Problem to be solved by the invention]

[0005] In the mold configuration proposed in Patent Document 1, when molding an optical element with a short distance between the centers of curvature of the upper and lower surfaces, the following problem occurs. For example, as shown in FIG. 2, if the optical axis Ax is tilted during molding of the optical element, the outer diameter height H of the optical element 13 In this case, the outer diameter runout R of the optical element relative to the optical axis Ax becomes large.

[0006] The "optical axis Ax" is the center of curvature C of the upper molding surface 112 of the upper mold 11 that molds the upper surface of the optical element. U and the center of curvature C of the lower molding surface 122 of the lower mold 12 that molds the lower surface of the optical element. LThe straight line connecting the outer diameter and height of the optical element H 13 " indicates the center of the height of the outer diameter part of the optical element after molding, and the center of the height of the side mold. In addition, "outer diameter runout R" is, in other words, the distance between the optical axis Ax and the central axis Ax of the side mold. 13 This indicates the distance between the

[0007] The present invention has been made in consideration of the above, and has an object to provide a die for molding optical elements that can reduce the outer diameter runout of an optical element relative to the optical axis when molding the optical element. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the optical element molding die of the present invention comprises an upper mold having a neck, an upper surface molding surface provided on the neck of the upper mold for molding the upper surface of an optical element, a lower mold having a neck, a lower surface molding surface provided on the neck of the lower mold for molding the lower surface of the optical element, a side mold into which the necks of the upper mold and the lower mold are inserted, and a sleeve in which the upper mold and the lower mold are housed, and the magnitude relationship between a first clearance indicating the clearance between a hole in the side mold and the neck of the lower mold and a second clearance indicating the clearance between a hole in the side mold and the neck of the upper mold is determined according to the magnitude relationship between a first distance indicating the distance between the center of curvature of the lower surface molding surface and the outer diameter height of the optical element, and a second distance indicating the distance between the center of curvature of the upper surface molding surface and the outer diameter height of the optical element.

[0009] In the optical element molding die according to the present invention, in the above invention, the magnitude relationship between the first clearance and the second clearance is the same as the magnitude relationship between the first distance and the second distance.

[0010] In the optical element molding die according to the present invention, in the above invention, the clearance between the inner surface of the sleeve and the upper and lower dies is smaller than the clearance between the inner surface of the sleeve and the side die. Effect of the Invention

[0011] According to the optical element molding die of the present invention, it is possible to reduce the deviation of the outer diameter of the optical element relative to the optical axis when molding the optical element. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of an optical element molding die according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram for explaining the outer diameter runout of an optical element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the optical element molding die according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiment, and the components in the following embodiment include those that are replaceable and easy for a person skilled in the art, or those that are substantially the same.

[0014] The configuration of an optical element molding die 1 according to an embodiment of the present invention will be described with reference to Fig. 1. The optical element molding die 1 is a die for molding optical elements made of, for example, glass. This optical element molding die 1 includes an upper die 11, a lower die 12, a side die 13, and a sleeve 14.

[0015] The upper die 11 has a cylindrical neck 111 extending toward the lower die 12. This neck 111 is the part of the upper die 11 that is inserted into the hole 131 of the side die 13. An upper molding surface 112 for molding the upper optically functional surface of the optical element is provided at the end of the neck 111. The upper die 11 is placed on the upper end surface of the sleeve 14.

[0016] The lower die 12 has a cylindrical neck 121 extending toward the upper die 11. This neck 121 is the part of the lower die 12 that is inserted into a hole 131 of the side die 13. An end of the neck 121 is provided with a lower surface molding surface 122 for molding the lower optically functional surface of the optical element.

[0017] The side mold 13 is provided with a hole 131 that penetrates the side mold 13 from top to bottom. A part of the inner surface of the hole 131 constitutes a side molding surface for molding the side (outer diameter part) of the optical element. In this embodiment, the center of the height of the side mold 13 is referred to as the "outer diameter height H of the optical element." 13 " is defined as

[0018] The upper die 11 and the lower die 12 are disposed in positions where their molding surfaces face each other with the side die 13 in between. Furthermore, the upper die 11, the lower die 12 and the side die 13 are disposed inside a sleeve 14. Furthermore, the side die 13 is placed on a step portion 141 provided inside the sleeve 14.

[0019] The sleeve 14 is for accommodating the upper die 11, the lower die 12, and the side die 13 therein. The sleeve 14 is formed in a cylindrical shape. Furthermore, a step 141 for placing the sleeve 14 thereon is formed inside the side die 13. The clearances between the various parts constituting the optical element molding die 1 are all set to about several μm to several tens of μm.

[0020] When an optical element is molded using the optical element molding die 1, for example, as shown in FIG. 11 , the central axis Ax of the lower die 12 12 and the central axis Ax of the side mold 13 13 Ideally, these should coincide with each other. In an optical element molded under such ideal conditions, the outer diameter runout of the optical element with respect to the optical axis Ax is zero. Note that the optical axis Ax shown in the figure indicates a straight line connecting the center of curvature of the upper molding surface 112 and the center of curvature of the lower molding surface 122.

[0021] On the other hand, for example, as shown in FIG. 2, when an optical element is molded by the optical element molding die 1, the center of curvature C U and the center of curvature C of the lower molding surface 122 L When the optical axis Ax connecting the above is tilted, the outer diameter height H of the optical element 13 The outer diameter runout R of the optical element becomes large at the outer diameter height H 13 and the optical axis Ax intersect at position P1, and the outer diameter height H 13 and the central axis Ax of the side mold 13 13 This indicates the distance between the position P2 where

[0022] Therefore, in the optical element molding die 1 according to the embodiment, the center of curvature C of the lower molding surface 122 L and outer diameter height H 13 (hereinafter referred to as the “first distance”) L1, and the center of curvature C of the upper molding surface 112 U and outer diameter height H 13 We focused on the relationship between the distance L2 (hereinafter referred to as the "second distance") and

[0023] In the optical element molding die 1 according to the embodiment, the magnitude relationship between the clearance between the hole 131 of the side die 13 and the neck 121 of the lower die 12 (hereinafter referred to as the "first clearance") and the clearance between the hole 131 of the side die 13 and the neck 111 of the upper die 11 (hereinafter referred to as the "second clearance") is determined according to the magnitude relationship between the first distance L1 and the second distance L2. In other words, in the optical element molding die 1, the magnitude relationship between the first clearance and the second clearance is set according to the magnitude relationship between the first distance L1 and the second distance L2.

[0024] For example, as shown in Fig. 2, when the first distance L1 is smaller than the second distance L2, the first clearance is set to be smaller than the second clearance. In this case, for example, the outer peripheral tolerance of the neck portion 121 of the lower mold 12 is set to "-2μm to -1μm" and the inner peripheral tolerance of the hole portion 131 of the side mold 13 is set to "0μm to 1μm", thereby setting the first clearance to "maximum 1μm". Also, the second clearance is set to "several μm".

[0025] On the other hand, in contrast to FIG. 2, when the first distance L1 is greater than the second distance L2, the first clearance is set to be greater than the second clearance. In this case, for example, the first clearance is set to "several μm." Also, the second clearance is set to "maximum 1 μm." In this way, the magnitude relationship between the first clearance and the second clearance is the same as the magnitude relationship between the first distance L1 and the second distance L2.

[0026] In the optical element molding die 1, the clearance between the inner surface of the sleeve 14 and the upper die 11 and the lower die 12 (hereinafter referred to as the "third clearance") is set smaller than the clearance between the inner surface of the sleeve 14 and the side die 13 (hereinafter referred to as the "fourth clearance"). In this case, for example, the third clearance is set to "several μm" and the fourth clearance is set to "several tens of μm."

[0027] The magnitudes of the first and second clearances do not depend on the dimensions (e.g., outer diameter height) of the optical element to be molded. In other words, whether a large-sized optical element or a small-sized optical element is molded, the magnitudes of the first and second clearances are set according to the first and second distances. This makes it possible to minimize the outer diameter runout R of the optical element relative to the optical axis Ax.

[0028] However, when molding a minute optical element having a diameter of, for example, about 5 mm, the central axis Ax of the upper die 11 is smaller than that when molding a large optical element. 11 The central axis Ax of the lower die 12 12 The deviation of the outer shape R due to the misalignment of the upper and lower surfaces becomes large. Therefore, the method of this embodiment is particularly effective when molding a minute optical element. The method of this embodiment is also particularly effective when molding an optical element in which the distance between the centers of curvature of the upper and lower surfaces is short.

[0029] In the optical element molding die 1 according to the present embodiment as described above, the center of curvature C Land the center of curvature C of the upper molding surface 112 U and outer diameter height H 13 The clearances (first clearance, second clearance) between the hole 131 of the side mold 13 and the neck portion 121 of the lower mold 12 and the neck portion 111 of the upper mold 11 are set according to the distance (first distance L1, second distance L2) between the hole 131 of the side mold 13 and the neck portion 121 of the lower mold 12 and the neck portion 111 of the upper mold 11. This makes it possible to reduce the outer diameter runout R of the optical element relative to the optical axis Ax when molding the optical element.

[0030] Although the optical element molding die according to the present invention has been specifically described above by way of the embodiment of the invention, the gist of the present invention is not limited to these descriptions and should be broadly interpreted based on the claims. Furthermore, it goes without saying that various changes and modifications based on these descriptions are also included in the gist of the present invention. [Explanation of symbols]

[0031] 1 Optical element molding die 11 Upper mold 111 Neck 112 Top molding surface 12 Lower mold 121 Neck 122 Bottom molding surface 13 Side type 131 Hole 14 Sleeve 141 Stepped section Ax optical axis Ax 11 ,Ax 12 ,Ax 13 central axis C L ,C U center of curvature H 13 Outer diameter height R Outer diameter runout

Claims

1. An upper mold having a neck portion; an upper surface molding surface provided on a neck portion of the upper mold for molding an upper surface of an optical element; A lower die having a neck portion; a lower surface molding surface provided on a neck portion of the lower mold for molding a lower surface of the optical element; a side mold into which the neck portions of the upper mold and the lower mold are inserted; a sleeve in which the upper die and the lower die are housed; Equipped with a magnitude relationship between a first clearance indicating a clearance between the hole of the side mold and the neck portion of the lower mold and a second clearance indicating a clearance between the hole of the side mold and the neck portion of the upper mold is determined according to a magnitude relationship between a first distance indicating the distance between the center of curvature of the lower molding surface and the outer diameter height of the optical element and a second distance indicating the distance between the center of curvature of the upper molding surface and the outer diameter height of the optical element, A magnitude relationship between the first clearance and the second clearance is the same as a magnitude relationship between the first distance and the second distance. Mold for molding optical elements.

2. a clearance between the inner surface of the sleeve and the upper and lower dies is smaller than a clearance between the inner surface of the sleeve and the side die; The optical element molding die according to claim 1 .

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