Lens manufacturing method

Abstract

To provide a manufacturing method for a lens capable of forming a lens having excellent optical performance without being limited by the number of gates.SOLUTION: A first mold 50 that forms one side of a lens and a plurality of second molds 51,52 that form the other side of the lens are prepared. A flow path forming part corresponding to a second gate G2 is provided at an abutting position between the first mold 50 and the one mold 51 selected from the plurality of the second molds. By filling a first cavity C1 with a resin through a first gate G1, a flow path corresponding to the flow path forming part is formed on an outer peripheral part of an intermediate body of the lens. By matching the first mold 50 in which the intermediate is located with the other mold 52 selected from the plurality of second molds 51,52, the flow path and the second gate G2 are put into a state of communicating with each other, and a second cavity C2 is filled with the resin from the second gate G2 through the flow path.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a lens. [Background technology]

[0002] For example, transparent resin lenses are formed by injection molding using a metal mold. Furthermore, among such lenses, lenses with a large thickness are formed into multiple layers by repeating injection molding while changing the metal mold (for example, see Patent Document 1 below).

[0003] Patent Document 1 listed below discloses a multi-layer molded product having three or more layers (N layers) which is formed by transferring an intermediate molded product as a first layer molded in a mold cavity with the smallest volume among a plurality of mold cavities having different volumes to a mold cavity with a larger volume and stack-molding a second layer, and then transferring the intermediate molded product sequentially to each mold cavity up to the Nth layer and stack-molding the same, wherein the flange of the multi-layer molded product is formed in two layers around its entire circumference, and a main portion of the multi-layer molded product, excluding the flange, is formed in the N layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-107229 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the lens described in the above-mentioned Patent Document 1, since two layers are formed over the entire circumference, the thickness of the gate must be half that of the outer periphery (brim portion), making the gate narrow.

[0006] In this case, the resin filling the cavity through the narrow gate may concentrate residual stress in the lens, which may adversely affect the optical performance of the lens. In particular, when the lens becomes thicker, the number of gates increases as the number of N layers increases. Therefore, the more the number of gates increases, the smaller the gate thickness becomes, which may adversely affect the optical performance of the lens as described above.

[0007] The present invention has been proposed in view of the above-mentioned conventional circumstances, and has an object to provide a lens manufacturing method capable of forming a lens with excellent optical performance without being limited by the number of gates. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides the following means. [1] A method for manufacturing a lens formed by injection molding using a mold, comprising the steps of: a first step of preparing a first mold for forming a flange portion that protrudes in a radially expanding direction from one surface side of the lens and an outer periphery of the lens over the entire circumference, and a plurality of second molds for forming the other surface side of the lens; a second step of forming a first cavity and a first gate by butting the first mold against one mold selected from the plurality of second molds; a third step of forming an intermediate lens by filling the first cavity with resin through the first gate; The first die in which the intermediate body is located is butted against another die selected from the plurality of second dies, so that the first gate is located in the second cavity and the flange portion in the circumferential direction. In succession a fourth step of forming adjacent second gates; and a fifth step of forming the lens intermediate or the lens by filling the second cavity with resin through the second gate, In the first step, a first cutout portion for forming the first gate and a second cutout portion for forming the second gate are provided at a position where the first mold butts against the first mold, and a flow path forming portion corresponding to the second gate is provided at a position where the first mold butts against the first mold; In the second step, at a position where the first mold and the first mold are butted against each other, the second cutout portion is closed by the flow path forming portion, and the first gate formed by the first cutout portion is in an open state; In the third step, a flow path having a thickness equivalent to that of the flange portion corresponding to the flow path forming portion is formed in the outer periphery of the intermediate body corresponding to the flange portion by cutting out a part of the flange portion in a thickness direction; In the fourth step, at a position where the first mold and the other mold are butted against each other, the second gate formed by the second cutout portion is opened and the flow path and the second gate are in communication with each other; A method for manufacturing a lens, wherein in the fifth step, resin is filled into the second cavity from the second gate through the flow path. [2] When forming the lens by sequentially repeating the fourth step and the fifth step while sequentially selecting another mold from the plurality of second molds, In the first step, a plurality of second notches are provided at a butting position of the first mold with the one mold, the number of which corresponds to the number of the other molds, and a plurality of flow path forming portions are provided at a butting position of the one mold with the first mold, the number of which corresponds to the number of the other molds; In the second step, the plurality of second cutout portions are closed by the plurality of flow path forming portions at a butting position of the first mold and the one mold, In the third step, a plurality of flow paths having a thickness equivalent to that of the flange portion corresponding to each of the plurality of flow path forming portions are formed in the outer peripheral portion of the intermediate body corresponding to the flange portion by cutting out a part of the flange portion in a thickness direction; In the fourth step, one of the plurality of flow paths is connected to the second gate; 2. The method for manufacturing a lens according to claim 1, wherein in the fifth step, a resin is filled into the second cavity through the second gate and the selected flow path. 。 Effect of the Invention

[0009] As described above, according to the present invention, it is possible to provide a lens manufacturing method capable of forming a lens with excellent optical performance without being limited by the number of gates. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional perspective view showing a configuration of a lens formed by a lens manufacturing method according to a first embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view showing a configuration of a manufacturing apparatus for the lens shown in FIG. [Diagram 3] FIG. 2 is a perspective view showing a configuration of a first mold. [Figure 4] FIG. 2 is a perspective view showing the configuration of a second mold for the first layer. [Diagram 5] FIG. 13 is a perspective view showing the configuration of a second mold for the second layer. [Figure 6] 2A to 2C are cross-sectional views illustrating a manufacturing process of the lens shown in FIG. [Figure 7] 2A to 2C are cross-sectional views illustrating a manufacturing process of the lens shown in FIG. [Figure 8] 2A to 2C are cross-sectional views illustrating a manufacturing process of the lens shown in FIG. [Figure 9] 2A to 2C are cross-sectional views illustrating a manufacturing process of the lens shown in FIG. [Figure 10] 7 is a side view showing a state in which a first mold and a second mold for a first layer are butted together in the step shown in FIG. 6. FIG. [Figure 11] 8 is a side view showing the configuration of an intermediate lens formed in the step shown in FIG. 7. [Figure 12] 9 is a side view showing a state in which the first mold and the second mold for the second layer are butted together in the step shown in FIG. 8. FIG. [Figure 13] 10A and 10B show the configuration of a lens formed in the process shown in FIG. 9, in which (A) is a perspective view seen from one side, and (B) is a perspective view seen from the other side. [Figure 14] 5A and 5B show the configuration of a lens formed by a lens manufacturing method according to a second embodiment of the present invention, where (A) is a plan view and (B) is a cross-sectional view. [Figure 15] 15 is a cross-sectional view showing the configuration of a manufacturing apparatus for the lens shown in FIG. 14. [Figure 16] FIG. 2 is a perspective view showing a configuration of a first mold. [Figure 17] FIG. 2 is a perspective view showing the configuration of a second mold for the first layer. [Figure 18] FIG. 13 is a perspective view showing the configuration of a second mold for the second layer. [Figure 19] FIG. 13 is a perspective view showing the configuration of a second mold for the third layer. [Figure 20] 15A to 15C are cross-sectional views illustrating a manufacturing process for the lens shown in FIG. 14. [Figure 21] 15A to 15C are cross-sectional views illustrating a manufacturing process for the lens shown in FIG. 14. [Figure 22] 15A to 15C are cross-sectional views illustrating a manufacturing process for the lens shown in FIG. 14. [Figure 23] 15A to 15C are cross-sectional views illustrating a manufacturing process for the lens shown in FIG. 14. [Figure 24] 15A to 15C are cross-sectional views illustrating a manufacturing process for the lens shown in FIG. 14. [Diagram 25] 15A to 15C are cross-sectional views illustrating a manufacturing process for the lens shown in FIG. 14. [Figure 26] 22 is a plan view showing the configuration of an intermediate lens formed in the step shown in FIG. 21. [Figure 27] 24 is a plan view showing the configuration of an intermediate lens formed in the step shown in FIG. 23. [Figure 28] 26 is a plan view showing the configuration of a lens formed in the process shown in FIG. 25. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, the dimensions of the components may be shown at different scales to make each component easier to see, and the dimensional ratios of each component may not necessarily be the same as in reality. Furthermore, the materials and the like exemplified in the following description are merely examples, and the present invention is not necessarily limited to them, and may be appropriately modified and implemented within the scope of the present invention.

[0012] [First embodiment] (lens) First, as a first embodiment of the present invention, a lens 1A shown in FIG. 1 will be described. FIG. 1 is a cross-sectional perspective view showing the configuration of the lens 1A.

[0013] As shown in Fig. 1, the lens 1A of this embodiment is a biconvex lens having one surface 2a that is a convex lens surface and the other surface 2b that is a convex lens surface. The lens 1A has a thick shape in which the one surface 2a protrudes more than the other surface 2b. A flange portion 2c is provided on the outer periphery of the lens 1A so as to protrude in the radial direction.

[0014] The lens 1A is made of a transparent thermoplastic resin such as polycarbonate, acrylic, etc. The lens 1A has a two-layer structure in which a first resin layer 3a forming one surface 2a of the lens 1A and a second resin layer 3b forming the other surface 2a of the lens 1A are laminated.

[0015] (Lens manufacturing equipment) Next, a manufacturing apparatus 100A for manufacturing the lens 1A shown in FIG. 2 will be described. FIG. 2 is a cross-sectional view showing the configuration of a manufacturing apparatus 100A for the lens 1A.

[0016] As shown in FIG. 2, the manufacturing apparatus 100A of this embodiment is an injection molding machine that uses a mold, and generally includes a movable side mounting portion 101, a fixed side mounting portion 102, a first injection unit 103, and a second injection unit 104.

[0017] The movable side attachment part 101 is provided so as to be movable in a direction approaching and separating from the fixed side attachment part 102 (front-rear direction in this embodiment) and in a direction perpendicular to the approaching and separating direction (up-down direction in this embodiment).

[0018] A first mold 50 for forming one surface 2a of the lens 1A is detachably attached to the side of the movable side attachment part 101 opposite to the movable side attachment part 102.

[0019] A plurality of first dies 50 (two in FIG. 2) are arranged radially and are connected to each other via runners R. The plurality of first dies 50 arranged radially are arranged vertically of the movable side mounting portion 101 in a row (two in this embodiment).

[0020] The fixed side mounting part 102 is connected to a first injection unit 103 located on the opposite side to the side facing the movable side mounting part 101 via a first sprue S1. The fixed side mounting part 102 is also connected to a second injection unit 104 located on the opposite side to the side facing the movable side mounting part 101 via a second sprue S2.

[0021] The first sprue S1 is located at the center of the fixed-side mounting part 102 and is provided branching out radially on the side facing the movable-side mounting part 101. The second sprue S2 is provided branching out via switching parts 104a on both the upper and lower sides of the first sprue S1.

[0022] On the side of the fixed side mounting part 102 facing the movable side mounting part 101, a plurality of (two in this embodiment) second molds 51, 52 for forming the other surface 2b of the lens 1A are detachably attached.

[0023] The multiple second molds 51, 52 are composed of a first layer second mold 51 for forming the first resin layer 3a of the lens 1A and a second layer second mold 52 for forming the second resin layer 3b of the lens 1A.

[0024] The first layer second mold 51 is located around the first sprue S1 and multiple molds (two molds in FIG. 2) are arranged radially. The second layer second mold 52 is located around the second sprue S2 and multiple molds (two molds in FIG. 2) are arranged radially. Therefore, the first layer second mold 51 is provided in the center of the fixed side mounting part 102. On the other hand, the second layer second mold 52 is provided on both the upper and lower sides of the fixed side mounting part 102 sandwiching the first layer second mold 51 therebetween.

[0025] The first injection unit 103 supplies molten resin to be the first resin layer 3a of the lens 1A through the first sprue S1. The second injection unit 104 supplies molten resin to be the second resin layer 3b of the lens 1A through the second sprue S2 while switching the second sprue S2 using the switching unit 104a.

[0026] In the manufacturing apparatus 100A of the present embodiment having the above-mentioned configuration, the first mold 50 and the first layer second mold 51 are butted together to form a first cavity C1 therebetween and a first gate G1 at the butted position. In this state, it is possible to fill the first cavity C1 with molten resin from the first gate G1 connected to the first sprue S1.

[0027] On the other hand, in the manufacturing apparatus 100A of this embodiment, the first mold 50 and the second mold 52 of the second layer are butted together to form a second cavity C2 therebetween and a second gate G2 at the butted position. In this state, it is possible to fill the second cavity C2 with molten resin from the second gate G2 connected to the second sprue S2 via the runner R.

[0028] (Lens manufacturing method) Next, a method for manufacturing the lens 1A using the manufacturing apparatus 100A shown in FIG. 2 will be described with reference to FIGS.

[0029] FIG. 3 is a perspective view showing the configuration of the first mold 50. FIG. 4 is a perspective view showing the configuration of the first layer second mold 51. FIG. 5 is a perspective view showing the configuration of the second layer second mold 52. FIG. 6 is a cross-sectional view for explaining the manufacturing process of the lens 1A. FIG. 7 is a cross-sectional view for explaining the manufacturing process of the lens 1A. FIG. 8 is a cross-sectional view for explaining the manufacturing process of the lens 1A. FIG. 9 is a cross-sectional view for explaining the manufacturing process of the lens 1A. FIG. 10 is a side view showing a state in which the first mold 50 and the first layer second mold 51 are butted together in the process shown in FIG. 6. FIG. 11 is a side view showing a configuration of the intermediate body M of the lens 1A formed in the process shown in FIG. 7. FIG. 12 is a side view showing a state in which the first mold and the second layer second mold are butted together in the process shown in FIG. 8. FIG. 13 shows the configuration of the lens 1A formed in the process shown in FIG. 9, where (A) is a perspective view seen from one surface 2a side, and (B) is a perspective view seen from the other surface 2b side.

[0030] When manufacturing the lens 1A of this embodiment, first, a first mold 50 for forming one surface 2a of the lens 1A shown in FIG. 3 and a plurality of second molds 51, 52 for forming the other surface 2b of the lens 1A shown in FIGS. 4 and 5 are prepared (hereinafter, this process is referred to as the "first process").

[0031] Of these, the first mold 50, as shown in Figure 3, has, on the side facing the second molds 51, 52, a concave surface 50a whose shape corresponds to one surface 2a (first resin layer 3a) of the lens 1A, and a step surface 50b whose shape corresponds to the flange portion 2c (first resin layer 3a) of the lens 1A.

[0032] The first mold 50 has a first cutout 50c for forming the first gate G1 and a second cutout 50d for forming the first gate G2 on the outer periphery on the side facing the second molds 51 and 52. The first cutout 50c and the second cutout 50d are adjacent to each other in the circumferential direction of the first mold 50, and are provided continuously therebetween.

[0033] On the other hand, the second mold 51 of the first layer is one mold selected from a plurality of second molds 51, 52, as shown in Figure 4, and has a convex surface 51a on the side facing the first mold 50, the shape of which corresponds to the first resin layer 3a.

[0034] Further, a flow path forming portion 53 corresponding to the second gate G2 is provided on the outer periphery of the convex surface 51a. The flow path forming portion 53 is configured by a protrusion that closes the second cutout portion 50d at the butt position of the first mold 50 and the second mold 51. Further, the shape of this protrusion has a shape that corresponds to the flow path T described later.

[0035] On the other hand, the second mold 52 of the second layer is another mold selected from a plurality of second molds 51, 52, as shown in Figure 5, and has a concave surface 52a on the side facing the first mold 50, the shape of which corresponds to the other surface 2b (second resin layer 3b) of the lens 1A.

[0036] Next, as shown in FIG. 6, the first mold 50 and the first layer second mold 51 are butted together to form the first cavity C1 and the first gate G1 (hereinafter, this step will be referred to as the "second step").

[0037] At this time, in the manufacturing apparatus 100A of this embodiment, the movable-side mounting part 101 is positioned above the fixed-side mounting part 102. As a result, the first mold 50 positioned below the movable-side mounting part 101 and the first layer second mold 51 positioned in the center of the fixed-side mounting part 102 are butted together.

[0038] In addition, in the manufacturing apparatus 100A of this embodiment, as shown in FIG. 10, at the butt position between the first mold 50 and the first layer second mold 51, the second cutout portion 50d is blocked by the flow path forming portion 53, and the first gate G1 formed by the first cutout portion 50c is in an open state.

[0039] Next, as shown in FIG. 7, molten resin L is filled into the first cavity G1 through the first gate G1 to form an intermediate body M of the lens 1A made of the first resin 3a (hereinafter, this step is referred to as the "third step").

[0040] 11, in the intermediate body M of the lens 1A, a first gate mark 2d made of the first resin layer 3a is formed at a position corresponding to the first gate portion G1, and a flow path T is formed at a position corresponding to the flow path forming portion 53. The flow path T is formed by cutting out a part of the flange portion 2c in the thickness direction.

[0041] Next, as shown in FIG. 8, the first mold 50 in which the intermediate body M is located is butted against the second mold 52 of the second layer to form a second cavity C2 and a second gate G2 (hereinafter, this step will be referred to as the "fourth step").

[0042] At this time, in the manufacturing apparatus 100A of this embodiment, the movable-side mounting part 101 is positioned below the fixed-side mounting part 102. That is, after the above-mentioned third step, the movable-side mounting part 101 moves downward, so that the first mold 50 positioned below the movable-side mounting part 101 and the second mold 52 of the second layer positioned below the fixed-side mounting part 102 are butted together.

[0043] Furthermore, in the manufacturing apparatus 100A of this embodiment, as shown in FIG. 12, at the butt position between the first mold 50 and the second mold 51 of the second layer, the second gate G2 formed by the second cutout portion 50d is opened, and this second gate G2 is connected to the flow path T.

[0044] 9, the second cavity C2 is filled with molten resin through the flow path T from the second gate G2 to form the second resin layer 3b (hereinafter, this step is referred to as the "fifth step"). This makes it possible to mold the lens 1A having a two-layer structure in which the first resin layer 3a and the second resin layer 3b are laminated.

[0045] 13, the molded lens 1A has a first gate mark 2d, a second gate mark 2e made of the second resin layer 3b at a position corresponding to the second gate portion G2, and a part of the flange portion 2c made of the second resin 3b at a position corresponding to the flow path T. Note that the first gate mark 2d and the second gate mark 2e are unnecessary parts of the lens 1A, and are therefore cut and removed after molding.

[0046] 8, when the movable-side mounting part 101 is positioned below the fixed-side mounting part 102, the first mold 50 positioned below the movable-side mounting part 101 and the second mold 52 of the second layer positioned below the fixed-side mounting part 102 are butted together. At the same time, the first mold 50 positioned above the movable-side mounting part 101 and the second mold 51 of the first layer positioned at the center of the fixed-side mounting part 102 are butted together.

[0047] Therefore, in this manufacturing apparatus 100A, in the state shown in Figure 9, it is possible to simultaneously perform the third step above the movable side mounting portion 101, in addition to the fifth step performed below the movable side mounting portion 101 described above.

[0048] Thereafter, in the manufacturing apparatus 100A of this embodiment, after the lens 1A formed in the fifth step is released from the mold, the movable side mounting portion 101 moves upward, so that the movable side mounting portion 101 is positioned downward relative to the fixed side mounting portion 102, as shown in Figure 6 described above.

[0049] At this time, the first mold 50 located above the movable mounting part 101 and the second mold 52 of the second layer located above the fixed mounting part 102 are in abutted state. At the same time, the first mold 50 located below the movable mounting part 101 and the second mold 51 of the first layer located in the center of the fixed mounting part 102 are in abutted state.

[0050] Therefore, in this manufacturing apparatus 100A, in the state shown in Figure 7, it is possible to simultaneously perform the third step below the movable side mounting portion 101, in addition to the fifth step performed above the movable side mounting portion 101 described above.

[0051] As described above, in the manufacturing apparatus 100A of this embodiment, while the third step is being performed below the movable mounting part 101, the fifth step can be performed above the movable mounting part 101. Also, in the manufacturing apparatus 100A of this embodiment, while the fifth step is being performed below the movable mounting part 101, the third step can be performed above the movable mounting part 101.

[0052] As a result, the manufacturing method of this embodiment makes it possible to efficiently manufacture the lens 1A.

[0053] As described above, in the manufacturing method of the lens 1A of the present embodiment, in the second step described above, a flow path forming portion 53 corresponding to the second gate G2 is provided at the butt position of the first mold 50 and the first layer first mold 51, and in the third step, a flow path T corresponding to the flow path forming portion 53 is formed in the outer periphery (flange portion 2c) of the preform M. Thereafter, in the fourth step, the flow path T and the second gate G2 are brought into communication with each other, and in the fifth step, resin is filled into the second cavity C2 from the second gate G2 through the flow path T.

[0054] This makes it possible to form a flow path T that is equivalent to the thickness of the flange portion 2c, thereby improving the fluidity of the resin that is filled into the second cavity C2 from the second gate G2 through this flow path T, and keeping the residual stress in the lens 1A low.

[0055] Therefore, according to the manufacturing method of this embodiment, it is possible to form a lens 1A with excellent optical performance without being limited by the number of gates.

[0056] [Second embodiment] (lens) Next, as a second embodiment of the present invention, for example, a lens 1B shown in FIG. 14 will be described.

[0057] 14 is a cross-sectional view showing the configuration of lens 1B. In the following description, the same parts as those in lens 1A will not be described and will be denoted by the same reference numerals in the drawings.

[0058] As shown in Fig. 14, the lens 1B of this embodiment has a three-layer structure in which the lens 1A has a first resin layer 3a forming one surface 2a of the lens 1A, a second resin layer 3b forming the other surface 2a of the lens 1A, and a third resin layer 3c formed between the first resin layer 3a and the second resin layer 3b. Otherwise, the lens 1B has basically the same structure as the lens 1A.

[0059] (Lens manufacturing equipment) Next, a manufacturing apparatus 100B for the lens 1B shown in FIG. 15 will be described. FIG. 15 is a cross-sectional view showing the configuration of a manufacturing apparatus 100B for the lens 1B.

[0060] As shown in FIG. 15, the manufacturing apparatus 100B of this embodiment includes a third injection unit 105 in addition to the configuration of the manufacturing apparatus 100A described above.

[0061] The fixed-side mounting part 102 is connected via a third sprue S3 to a third injection unit 105 located on the opposite side to the side facing the movable-side mounting part 101. The third sprue S3 is provided branching off via a switching part 105a on both the upper and lower sides of the first sprue S1. The second sprue S2 and the third sprue S3 are arranged in the reverse order in the vertical direction on the upper and lower sides of the first sprue S1.

[0062] A first mold 60 for forming one surface 2a of the lens 1B is detachably attached to the side of the movable-side attachment part 101 opposite to the movable-side attachment part .

[0063] A plurality of first dies 60 (two in FIG. 15) are arranged radially and are connected to each other via runners R. The plurality of first dies 60 arranged radially are arranged in a row in the up-down direction of the movable-side mounting portion 101 (three in this embodiment).

[0064] On the side of the fixed side mounting part 102 facing the movable side mounting part 101, a plurality of (three in this embodiment) second molds 61, 62, 63 for forming the other surface 2b of the lens 1B are detachably attached.

[0065] The multiple second molds 61, 62, 63 are composed of a first layer second mold 61 for forming the first resin layer 3a of the lens 1B, a second layer second mold 62 for forming the third resin layer 3c of the lens 1B, and a third layer second mold 63 for forming the second resin layer 3b of the lens 1B.

[0066] The first layer second mold 61 is located around the first sprue S1 and multiple molds (two molds in FIG. 15) are arranged radially. The second layer second mold 62 is located around the second sprue S2 and multiple molds (two molds in FIG. 15) are arranged radially. The third layer second mold 63 is located around the third sprue S3 and multiple molds (two molds in FIG. 15) are arranged radially.

[0067] Therefore, the first layer second mold 61 is provided in the center of the fixed side mounting portion 102. Meanwhile, the second layer second mold 62 is provided on both the upper and lower sides of the first layer second mold 61 of the fixed side mounting portion 102. Meanwhile, the third layer second mold 63 is provided on both the upper and lower sides of the first layer second mold 61 of the fixed side mounting portion 102. Also, the second layer second mold 62 and the third layer second mold 63 are arranged in the reverse order in the vertical direction on the upper and lower sides of the first layer second mold 61.

[0068] The first injection unit 103 supplies molten resin to become the first resin layer 3a of the lens 1A through the first sprue S1. The second injection unit 104 supplies molten resin to become the third resin layer 3c of the lens 1A through the second sprue S2 while switching the second sprue S2 with the switching unit 104a. The third injection unit 105 supplies molten resin to become the second resin layer 3b of the lens 1B through the third sprue S3 while switching the third sprue S3 with the switching unit 105a.

[0069] In the manufacturing apparatus 100B of the present embodiment having the above-mentioned configuration, the first mold 60 and the first layer second mold 61 are butted together to form a first cavity C1 therebetween and a first gate G1 at the butted position. In this state, it is possible to fill the first cavity C1 with molten resin from the first gate G1 connected to the first sprue S1.

[0070] On the other hand, in the manufacturing apparatus 100B of this embodiment, the first mold 60 and the second mold 62 of the second layer are butted together to form a second cavity C2A therebetween and a second gate G2A at the butted position. In this state, it is possible to fill the second cavity C2A with molten resin from the second gate G2A connected to the second sprue S2 via the runner R.

[0071] On the other hand, in the manufacturing apparatus 100B of this embodiment, the first mold 60 and the third mold 63 of the third layer are butted together to form a second cavity C2B therebetween and a second gate G2B at the butted position. In this state, it is possible to fill the second cavity C2B with molten resin from the second gate G2B connected to the third sprue S3 via the runner R.

[0072] (Lens manufacturing method) Next, a method for manufacturing the lens 1B using the manufacturing apparatus 100B shown in FIG. 15 will be described with reference to FIGS. FIG. 16 is a perspective view showing the configuration of the first mold 60. FIG. 17 is a perspective view showing the configuration of the first layer second mold 61. FIG. 18 is a perspective view showing the configuration of the second mold 62 of the second layer. FIG. 19 is a perspective view showing the configuration of the third layer second mold 63. FIG. 20 is a cross-sectional view for explaining the manufacturing process of the lens 1B. FIG. 21 is a cross-sectional view for explaining the manufacturing process of the lens 1B. FIG. 22 is a cross-sectional view for explaining the manufacturing process of the lens 1B. FIG. 23 is a cross-sectional view for explaining the manufacturing process of the lens 1B. FIG. 24 is a cross-sectional view for explaining the manufacturing process of the lens 1B. FIG. 25 is a cross-sectional view for explaining the manufacturing process of the lens 1B. FIG. 26 is a side view showing the configuration of the intermediate body M1 of the lens 1B formed in the process shown in FIG. 21. FIG. 27 is a side view showing the configuration of the intermediate body M2 of the lens 1B formed in the process shown in FIG. 23. FIG. 28 is a plan view showing the configuration of the lens 1B formed in the process shown in FIG. 25.

[0073] When manufacturing the lens 1B of this embodiment, first, in the first step, a first mold 60 for forming one surface 2a of the lens 1B shown in FIG. 16 and multiple (three in this embodiment) second molds 61, 62, 63 for forming the other surface 2b of the lens 1B shown in FIGS. 17 to 19 are prepared.

[0074] Of these, the first mold 60, as shown in Figure 16, has, on the side facing the second molds 61, 62, 63, a concave surface 60a whose shape corresponds to one surface 2a (first resin layer 3a) of the lens 1B, and a step surface 60b whose shape corresponds to the flange portion 2c (first resin layer 3a) of the lens 1B.

[0075] In addition, the first mold 60 has, on the outer periphery on the side facing the second molds 61, 62, 63, a first cutout 60c that forms the first gate G1, a second cutout 60d that forms the second gate G2A, and a third cutout 60e that forms the second gate G2B.

[0076] Among these, the first cutout portion 60c and the third cutout portion 60e are adjacent to each other in the circumferential direction of the first mold 60, and are provided continuously therebetween. On the other hand, the second cutout portion 60d is provided at a position separated from the first cutout portion 60c and the third cutout portion 60e.

[0077] On the other hand, the second mold 61 for the first layer is one mold selected from a plurality of second molds 61, 62, 63, as shown in Figure 17, and has a convex surface 61a on the side facing the first mold 60, the shape of which corresponds to the first resin layer 3a.

[0078] Further, a flow path forming portion 53A corresponding to the second gate G2A, and a flow path forming portion 53B corresponding to the second gate G2B are provided on the outer periphery of the convex surface 61a.

[0079] The flow path forming portion 53A is configured by a protrusion that closes the second cutout portion 60d at the butt position of the first mold 60 and the second mold 61. The shape of this protrusion corresponds to the shape of the flow path T1 described later.

[0080] The flow path forming portion 53B is configured by a protrusion that closes the third cutout portion 60e at the butt position of the first mold 60 and the second mold 61. The shape of this protrusion corresponds to the shape of the flow path T2 described later.

[0081] On the other hand, the second mold 62 of the second layer is another mold selected from a plurality of second molds 61, 62, 63, as shown in Figure 18, and has a convex surface 62a on the side facing the first mold 60, the shape of which corresponds to the third resin layer 3c.

[0082] In addition, a flow path forming portion 53C corresponding to the second gate G2B is provided on the outer periphery of the convex surface 62a. The flow path forming portion 53C is configured by a protrusion that closes the third cutout portion 60e at the butt position of the first mold 60 and the second mold 62. In addition, the shape of this protrusion has a shape that corresponds to the flow path T2 described later.

[0083] On the other hand, the third layer second mold 63 is another mold selected from a plurality of second molds 61, 62, 63, as shown in Figure 19, and has a concave surface 63a on the side facing the first mold 60, the shape of which corresponds to the other surface 2b of the lens 1B (second resin layer 3b).

[0084] Next, in the second step, as shown in FIG. 20, a first mold 60 and a second mold 61 of the first layer are butted together to form a first cavity C1 and a first gate G1.

[0085] At this time, in the manufacturing apparatus 100B of this embodiment, the movable-side mounting part 101 is positioned above the fixed-side mounting part 102. As a result, the first mold 60 positioned below the movable-side mounting part 101 and the first layer second mold 61 positioned in the center of the fixed-side mounting part 102 are butted together.

[0086] Furthermore, in the manufacturing apparatus 100A of this embodiment, at the butt position between the first mold 60 and the first layer second mold 61, the second cutout portion 60d is blocked by the flow path forming portion 53A, the third cutout portion 60e is blocked by the flow path forming portion 53B, and the first gate G1 formed by the first cutout portion 60c is in an open state.

[0087] Next, in the third step, as shown in FIG. 21, molten resin L is filled into the first cavity G1 through the first gate G1 to form an intermediate body M1 of the lens 1B made of the first resin 3a.

[0088] 26, in the intermediate body M1 of the lens 1B, a first gate mark 2d made of the first resin layer 3a is formed at a position corresponding to the first gate portion G1, a flow path T1 is formed at a position corresponding to the flow path forming portion 53A, and a flow path T2 is formed at a position corresponding to the flow path forming portion 53B. The flow paths T1 and T2 are each formed by cutting out a part of the flange portion 2c in the thickness direction.

[0089] Next, as the fourth step of the first round, as shown in FIG. 22, the first mold 60 in which the intermediate body M1 is located is butted against the second mold 62 of the second layer to form the second cavity C2A and the second gate G2A.

[0090] At this time, in the manufacturing apparatus 100B of this embodiment, the movable-side mounting part 101 is located in the center relative to the fixed-side mounting part 102. That is, after the above-mentioned third step, the movable-side mounting part 101 moves downward relative to the fixed-side mounting part 102, so that the first mold 60 located below the movable-side mounting part 101 and the second mold 62 of the second layer located below the fixed-side mounting part 102 are butted together.

[0091] Furthermore, in the manufacturing apparatus 100B of this embodiment, at the butt position between the first mold 60 and the second mold 62 of the second layer, the third cutout portion 60e is blocked by the flow path forming portion 53C, and the second gate G2A formed by the second cutout portion 60d is opened, and this second gate G2A is connected to the flow path T1.

[0092] Next, as the first fifth step, as shown in FIG. 23, molten resin L is filled into the second cavity G2A through the flow path T1 from the second gate G2A to form an intermediate body M2 of the lens 1B made of the first resin 3a and the third resin 3c.

[0093] As shown in FIG. 27, the intermediate body M2 of the lens 1A is formed with a first gate mark 2d, a second gate mark 2e made of the third resin layer 3c at a position corresponding to the second gate portion G2A, a part of the flange portion 2c made of the second resin layer 3b at a position corresponding to the flow path T1, and a flow path T2 at a position corresponding to the flow path forming portion 53C.

[0094] Next, as the fourth step of the second round, as shown in FIG. 24, the first mold 60 in which the intermediate body M2 is located is butted against the second mold 63 of the third layer to form the second cavity C2B and the second gate G2B.

[0095] At this time, in the manufacturing apparatus 100B of this embodiment, the movable-side mounting part 101 is positioned below the fixed-side mounting part 102. That is, after the first fifth step described above, the movable-side mounting part 101 moves downward relative to the fixed-side mounting part 102, so that the first mold 60 positioned below the movable-side mounting part 101 and the third layer second mold 63 positioned below the fixed-side mounting part 102 are butted together.

[0096] Furthermore, in the manufacturing apparatus 100B of this embodiment, at the butt position between the first mold 60 and the second mold 63 of the third layer, the second gate G2B formed by the third cutout portion 60e is opened, and this second gate G2B is connected to the flow path T2.

[0097] Next, in the second fifth step, the second cavity C2B is filled with molten resin through the flow path T2 from the second gate G2B to form the second resin layer 3b, as shown in Fig. 25. This makes it possible to mold the lens 1B having a three-layer structure in which the first resin layer 3a, the third resin layer 3c, and the second resin layer 3b are laminated.

[0098] 28, the molded lens 1B has a first gate mark 2d, a second gate mark 2e, a third gate mark 2f made of the second resin layer 3b at a position corresponding to the second gate portion G2B, a part of the flange portion 2c made of the third resin layer 3c at a position corresponding to the flow path T1, and a part of the flange portion 2c made of the second resin layer 3b at a position corresponding to the flow path T2. Note that the first gate mark 2d, the second gate mark 2e, and the third gate mark 2f are unnecessary parts of the lens 1B, and are therefore cut and removed after molding.

[0099] 22, when the movable-side mounting part 101 is located at the center with respect to the fixed-side mounting part 102, the first mold 60 located below the movable-side mounting part 101 and the second mold 62 of the second layer located below the fixed-side mounting part 102 are in abutted state. At the same time, the first mold 60 located at the center of the movable-side mounting part 101 and the second mold 61 of the first layer located at the center of the fixed-side mounting part 102 are in abutted state.

[0100] Therefore, in this manufacturing apparatus 100B, in the state shown in Figure 23, it is possible to simultaneously perform the third step in the center of the movable side mounting portion 101, in addition to the first fifth step which is performed below the movable side mounting portion 101 described above.

[0101] Thereafter, in the manufacturing apparatus 100B of this embodiment, the movable side mounting portion 101 moves downward, so that the movable side mounting portion 101 is positioned downward relative to the fixed side mounting portion 102, as shown in Figure 24 described above.

[0102] At this time, the first mold 60 located below the movable side mounting portion 101 and the third layer second mold 63 located below the fixed side mounting portion 102 are in abutted state. At the same time, the first mold 60 located in the center of the movable side mounting portion 101 and the second layer second mold 62 located below the fixed side mounting portion 102 are in abutted state. At the same time, the first mold 60 located above the movable side mounting portion 101 and the first layer second mold 61 located in the center of the fixed side mounting portion 102 are in abutted state.

[0103] Therefore, in this manufacturing apparatus 100A, in the state shown in Figure 24, in addition to the second fifth step performed below the movable side mounting portion 101 described above, it is possible to simultaneously perform the first fifth step in the central part of the movable side mounting portion 101 and the third step above the movable side mounting portion 101.

[0104] Thereafter, in the manufacturing apparatus 100B of this embodiment, after the lens 1B formed in the second fifth step is released from the mold, the movable side mounting portion 101 moves upward, so that the movable side mounting portion 101 is positioned upward relative to the fixed side mounting portion 102, as shown in Figure 20 described above.

[0105] At this time, the first mold 60 located below the movable side mounting portion 101 and the first layer second mold 61 located at the center of the fixed side mounting portion 102 are in abutted state. At the same time, the first mold 60 located at the center of the movable side mounting portion 101 and the third layer second mold 63 located above the fixed side mounting portion 102 are in abutted state. At the same time, the first mold 60 located above the movable side mounting portion 101 and the second layer second mold 62 located above the fixed side mounting portion 102 are in abutted state.

[0106] Therefore, in this manufacturing apparatus 100A, in the state shown in Figure 21, in addition to the third step performed below the movable side mounting portion 101 described above, it is possible to simultaneously perform a second fifth step in the central portion of the movable side mounting portion 101 and a first fifth step above the movable side mounting portion 101.

[0107] Thereafter, in the manufacturing apparatus 100B of this embodiment, after the lens 1B formed in the second fifth step is released from the mold, the movable side mounting portion 101 moves downward, so that the movable side mounting portion 101 is positioned in the center relative to the fixed side mounting portion 102, as shown in Figure 22 above.

[0108] At this time, the first mold 60 located below the movable side mounting portion 101 and the second mold 62 of the second layer located below the fixed side mounting portion 102 are in abutted state. At the same time, the first mold 60 located at the center of the movable side mounting portion 101 and the second mold 61 of the first layer located at the center of the fixed side mounting portion 102 are in abutted state. At the same time, the first mold 60 located above the movable side mounting portion 101 and the second mold 63 of the third layer located above the fixed side mounting portion 102 are in abutted state.

[0109] Therefore, in this manufacturing apparatus 100B, in the state shown in Figure 23, in addition to the first fifth step performed below the movable side mounting portion 101 described above, it is possible to simultaneously perform a third step in the center of the movable side mounting portion 101 and a second fifth step above the movable side mounting portion 101.

[0110] In this manner, in the manufacturing apparatus 100B of this embodiment, while the third step is being performed below the movable side mounting portion 101, the second fifth step can be performed in the central portion of the movable side mounting portion 101, and the first fifth step can be performed above the movable side mounting portion 101.

[0111] In addition, in the manufacturing apparatus 100B of this embodiment, while the first fifth step is being performed below the movable side mounting portion 101, the third step can be performed in the central portion of the movable side mounting portion 101, and the second fifth step can be performed above the movable side mounting portion 101.

[0112] Furthermore, in the manufacturing apparatus 100B of this embodiment, while the second fifth step is being performed below the movable side mounting portion 101, the first fifth step can be performed in the central portion of the movable side mounting portion 101, and the third step can be performed above the movable side mounting portion 101.

[0113] As a result, the manufacturing method of this embodiment makes it possible to efficiently manufacture the lens 1B.

[0114] As described above, in the manufacturing method of the lens 1B of this embodiment, in the second step described above, a plurality of flow path forming portions 53A, 53B corresponding to the number (two in this embodiment) of the second layer second mold 62 and the third layer second mold 63 are provided at the butting position of the first mold 61 and the first layer second mold 61, and in the third step, a plurality (two in this embodiment) of flow paths T1, T2 corresponding to each of the plurality of flow path forming portions 53A, 53B are formed in the outer periphery (flange portion 2c) of the intermediate body M1.

[0115] Then, in the first fourth step, a flow path T1 selected from the multiple flow paths T1, T2 is connected to the second gate G2A, and in the first fifth step, resin is filled into the second cavity C2A from the second gate G2A through the flow path T1.

[0116] Furthermore, in the fourth process of the second round, a flow path T2 selected from the multiple flow paths T1, T2 is made to communicate with the second gate G2B, and in the fifth process of the second round, resin is filled into the second cavity C2B from the second gate G2B through the flow path T2.

[0117] This makes it possible to form flow paths T1, T2 having a thickness equivalent to that of the flange portion 2c, thereby improving the fluidity of the resin that is filled into the second cavities C2A, C2B from the second gates G2A, G2B through these flow paths T1, T2, and keeping the residual stress in the lens 1B low.

[0118] Therefore, according to the manufacturing method of this embodiment, it is possible to form a lens 1B with excellent optical performance without being limited by the number of gates.

[0119] The present invention is not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the above embodiments illustrate the case where a lens 1A having a two-layer structure and the case where a lens 1B having a three-layer structure are formed, but the number of resin layers constituting the lens is not particularly limited.

[0120] That is, in the lens manufacturing method to which the present invention is applied, a plurality of second dies corresponding to the number of resin layers constituting the lens are prepared, and a second die is sequentially selected from the plurality of second dies while the fourth and fifth steps are sequentially repeated, thereby making it possible to form a multi-layer lens.

[0121] Furthermore, although the lens manufacturing method to which the present invention is applied is suitably used when forming a biconvex lens having a large thickness, such as lenses 1A and 1B described above, the shape of the lens is not particularly limited.

[0122] In addition, in the manufacturing apparatuses 100A, 100B for the above-mentioned lenses 1A, 1B, the movable side mounting portion 100 is configured to move in the vertical direction relative to the fixed side mounting portion 102, but it is also possible to configure the alignment position between the first mold and multiple second molds to be changed by rotating the movable side mounting portion about an axis relative to the fixed side mounting portion. [Explanation of symbols]

[0123] Reference Signs List 1A, 1B... Lens 2a... One surface 2b... Other surface 2c... Flange portion 2d... First gate mark 2e... Second gate mark 2f... Third gate mark 3a... First resin layer 3b... Second resin layer 3c... Third resin layer 50... First mold 51... First layer second mold 52... Second layer second mold 53, 53A, 53B, 53C... Flow path forming portion 60... First mold 61... First layer second mold 62... Second layer second mold 63... Third layer second mold 100A, 100B... Manufacturing device 101... Movable side mounting portion 102... Fixed side mounting portion 103... First injection unit 104... Second injection unit 105... Third injection unit R... Runner S1... First sprue S2...Second sprue S3...Third sprue C1...First cavity C2, C2A, C2B...Second cavity G1...First gate G2, G2A, G2B...Second gate T, T1, T2...Flow path L...Resin M, M1, M2...Intermediate body

Claims

1. A method for manufacturing a lens formed by injection molding using a mold, comprising the steps of: a first step of preparing a first mold for forming a flange portion that protrudes in a radially expanding direction from one surface side of the lens and an outer periphery of the lens over the entire circumference, and a plurality of second molds for forming the other surface side of the lens; a second step of forming a first cavity and a first gate by butting the first mold against one mold selected from the plurality of second molds; a third step of forming an intermediate lens by filling the first cavity with resin through the first gate; a fourth step of butting the first die in which the intermediate body is located against another die selected from the plurality of second dies to form a second cavity and a second gate adjacent to the first gate in the circumferential direction in the flange portion; and a fifth step of forming the lens intermediate or the lens by filling the second cavity with resin through the second gate, In the first step, a first cutout portion for forming the first gate and a second cutout portion for forming the second gate are provided at a position where the first mold is butted against the first mold, and a flow path forming portion corresponding to the second gate is provided at a position where the first mold is butted against the first mold; In the second step, at a position where the first mold and the first mold are butted against each other, the second cutout portion is closed by the flow path forming portion, and the first gate formed by the first cutout portion is in an open state; In the third step, a flow path having a thickness equivalent to that of the flange portion corresponding to the flow path forming portion is formed in the outer periphery of the intermediate body corresponding to the flange portion by cutting out a part of the flange portion in a thickness direction; In the fourth step, at a position where the first mold and the other mold are butted against each other, the second gate formed by the second cutout portion is opened and the flow path and the second gate are in communication with each other; A method for manufacturing a lens, wherein in the fifth step, resin is filled into the second cavity from the second gate through the flow path.

2. When forming the lens by sequentially repeating the fourth step and the fifth step while sequentially selecting another mold from the plurality of second molds, In the first step, a plurality of second notches are provided at a butting position of the first mold with the one mold, the number of which corresponds to the number of the other molds, and a plurality of flow path forming portions are provided at a butting position of the one mold with the first mold, the number of which corresponds to the number of the other molds; In the second step, the plurality of second cutout portions are closed by the plurality of flow path forming portions at a butting position of the first mold and the one mold, In the third step, a plurality of flow paths having a thickness equivalent to that of the flange portion corresponding to each of the plurality of flow path forming portions are formed in the outer peripheral portion of the intermediate body corresponding to the flange portion by cutting out a part of the flange portion in a thickness direction; In the fourth step, one of the plurality of flow paths is connected to the second gate; 2. The method for manufacturing a lens according to claim 1, wherein in the fifth step, a resin is filled into the second cavity through the selected flow path from the second gate.

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