Multi-layer formed lens

Abstract

The present invention provides a multilayer molded lens with excellent optical properties obtained by injecting and filling a molten resin with low pressure loss and no foreign matter evenly. The multilayer molded lens (5) having three or more layers (N layers) includes: a pair of lens surfaces (50) intersecting with the lens optical axis (L); and a lens side surface (30) provided between the pair of lens surfaces (50) on the side of the lens optical axis (L). At the central portion in the width direction of the lens side surface (30), a gate mark group is formed by integrating the traces of side gates of each layer from the first layer to the Nth layer, that is, N gate marks (11t to 14t).

Description

Technical Field

[0001] The present disclosure relates to a multi-layer molded lens that is multi-layer molded by injection molding. Background Art

[0002] In multi-layer molding, for example, as disclosed in Patent Document 1, an intermediate molded product of a first layer molded in a mold cavity having the smallest volume among a plurality of mold cavities having different volumes is transferred to a mold cavity having a larger volume and laminated to mold a second layer, and then the intermediate molded product is sequentially transferred to each mold cavity up to the Nth layer and laminated to mold each layer. Moreover, the gates of the first layer and the Nth layer are provided on the outer peripheral end surface of the lens, and the gates of each layer from the second layer to the (N - 1)th layer are provided on the lens surface.

[0003] Patent Document 1: Japanese Patent Laid-Open No. 2013 - 107229

[0004] However, since the gates of each layer from the second layer to the (N - 1)th layer are provided on the lens surface, irregular changes in the viscosity of the molten resin due to molding defects such as cold material, flow marks, and radiating streaks are not completely melted by the molding of the next layer, and sometimes remain as colloidal foreign substances that deteriorate the optical properties. In addition, there is also a case where foreign substances directly flow from the hot runner into the cavity because there is no runner or runner.

[0005] In addition, according to the molding process of the technique of Patent Document 1, the cumulative cooling time of each layer is shorter for the upper layer. That is, the cooling time of the Nth layer is shorter than that of any other layer. Furthermore, since the cooling of the Nth layer, which is the outer surface of the lens, cannot be sufficiently performed, the surface of the Nth layer, which is optically important, shrinks and minute recesses remain. Therefore, the optical properties of the lens deteriorate. In order to eliminate this problem, it is necessary to extend the cooling time of the Nth layer, and it is inevitable to delay the molding time. Summary of the Invention

[0006] The present disclosure has been made in view of the above problems, and an object thereof is to provide a multi-layer molded lens having excellent optical properties obtained by uniformly injecting and filling a molten resin with low pressure loss without foreign matter mixing.

[0007] In order to achieve the above object, according to one aspect of the present disclosure, a multi-layer molded lens is a multi-layer molded lens of three or more layers (N layers), and includes: a pair of lens surfaces that intersect the lens optical axis; and a lens side surface that is provided between the pair of lens surfaces on the side of the lens optical axis, and in the central portion in the width direction of the lens side surface, a gate mark group is formed by integrating N gate marks that are traces of side gates of each layer from the first layer to the Nth layer.

[0008] According to the present disclosure, the multi-layer molded lens is molded by injecting molten resin into a cavity for molding the first layer and the Nth layer that form a pair of lens surfaces respectively from a side gate, and a cavity for molding the second layer to the (N - 1)th layer that form the inside of the lens. Traces of the side gates of each layer from the first layer to the Nth layer, that is, N gate marks, are formed at the center of the width direction of the lens side surface. Thus, the multi-layer molded lens is filled by the molten resin with low pressure loss and no foreign matter mixed therein flowing evenly to each corner of its cavity, and the viscosity of the molten resin in the cavity becomes uniform for molding, so that an excellent effect of having excellent optical characteristics is achieved. In addition, gate cutting is performed in a state where the side gates of each layer from the first layer to the Nth layer are integrated, and a gate mark group formed by integrating the N gate marks is formed. Thus, the cutting of the N side gates from the first layer to the Nth layer becomes extremely easy, and an excellent effect of reducing the manufacturing cost can be achieved.

[0009] In addition, according to another aspect of the present disclosure, the gate mark of the first layer of the multi-layer molded lens has the largest cross-sectional area among the N gate marks.

[0010] According to the present disclosure, the cavity for the first layer with a relatively large volume and forming the lens surface is filled and molded evenly by the molten resin with extremely low pressure loss, so that an excellent effect of further improving the optical characteristics of the lens is achieved.

[0011] In addition, according to another aspect of the present disclosure, the gate marks of a specified multi-layer among the first layer to the Nth layer of the multi-layer molded lens are arranged side by side along the width direction of the lens side surface.

[0012] According to the present disclosure, since the gate marks of the specified multi-layer are arranged side by side along the width direction of the lens side surface, the thickness of the entire gate mark group can be suppressed to be small, the cutting of the side gate group becomes easy, and an excellent effect of reducing the manufacturing cost can be achieved.

[0013] In addition, according to another aspect of the present disclosure, the gate marks of the specified multi-layer arranged side by side of the multi-layer molded lens are the gate marks of any multi-layer from the second layer to the (N - 1)th layer.

[0014] According to the present disclosure, since the gate marks of any multi-layer from the second layer to the (N - 1)th layer that form the inside of the lens are arranged side by side along the width direction of the lens side surface, the side gates of the cavities for the first layer and the Nth layer that directly affect the appearance quality and optical characteristics of the lens can be arranged at the center position of the lens side surface as much as possible, and an excellent effect of improving the appearance quality and optical characteristics of the lens is achieved.

[0015] In addition, according to another aspect of the present disclosure, the total thickness of the gates stacked along the optical axis direction of the multi-layer molded lens is 3 to 10 mm.

[0016] According to the present disclosure, the side gate of the cavity for forming the first layer and the Nth layer that directly affects the appearance quality and optical characteristics of the lens is arranged at the center position as much as possible on the side surface of the lens, and the cutting of the side gate group becomes easy, achieving an excellent effect of reducing the manufacturing cost.

[0017] In addition, according to another aspect of the present disclosure, the maximum thickness of the Nth layer of the multi-layer molded lens is smaller than the maximum thickness of the (N - 1)th layer.

[0018] According to the present disclosure, since the maximum thickness of the Nth layer of the multi-layer molded lens is smaller than the maximum thickness of the (N - 1)th layer, problems such as sink marks caused by insufficient cooling of the Nth layer, which has the shortest cooling time compared to other layers in the molding cycle, are alleviated, achieving an excellent effect of improving the optical characteristics of the lens.

[0019] In addition, according to another aspect of the present disclosure, the maximum thickness of the Nth layer of the multi-layer molded lens is 2 to 4 mm.

[0020] According to the present disclosure, since the maximum thickness of the Nth layer is 2 to 4 mm and the molten resin easily flows in the cavity to mold the Nth layer, an excellent effect of improving the optical characteristics of the lens is achieved.

[0021] In addition, according to another aspect of the present disclosure, the multi-layer molded lens has a micro uneven shape on the outer surface of the Nth layer.

[0022] According to the present disclosure, by forming only on the cavity surface of the Nth layer in the cavity used from the first layer to the Nth layer, a micro uneven shape can be formed on the lens surface, achieving an excellent effect of being able to manufacture a multi-layer molded lens with desired optical effects such as a blurring effect at a relatively low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is through Figure 5 The I-I arrow of shows a perspective view of the multi-layer molded lens of the embodiment.

[0024] Figure 2 is a perspective view showing the first layer of the multi-layer molded lens as an intermediate molded body.

[0025] Figure 3 is a perspective view showing the second layer of the multi-layer molded lens together with the intermediate molded body of the first layer as an intermediate molded body for the third layer.

[0026] Figure 4It is a perspective view showing the third layer in the multi-layer formed lens together with the intermediate formed body including the first layer and the second layer as the intermediate formed body for the fourth layer.

[0027] Figure 5 It is a perspective view showing the fourth layer in the multi-layer formed lens together with the intermediate formed body including the first layer, the second layer, and the third layer as the completed formed body.

[0028] Figure 6 It is through Figure 7 and Figure 8 The side view of the partial cross-section of the molding device and the die device for simultaneously manufacturing the multi-layer formed lens including the first layer to the fourth layer is shown by the VI-VI arrow.

[0029] Figure 7 It is the front view showing the mold clamping surface of the second cavity block in the die device.

[0030] Figure 8 It is the front view showing the mold clamping surface of the first cavity block in the die device.

[0031] Figure 9 It is through Figure 7 and Figure 8 The cross-sectional side view of the cavity for forming the second layer in the die device is shown by the IX-IX arrow.

[0032] Figure 10 It is through Figure 7 and Figure 8 The cross-sectional side view of the cavity for forming the third layer in the die device is shown by the X-X arrow.

[0033] Figure 11 It is through Figure 7 and Figure 8 The cross-sectional side view of the cavity for forming the fourth layer in the die device is shown by the XI-XI arrow.

[0034] Figure 12 It is the partial enlarged cross-sectional view of the cavity surface showing the shape of the minute unevenness.

[0035] Figure 13 It is the partial enlarged cross-sectional view of the cavity surface showing another shape of the minute unevenness.

[0036] Figure 14 It is the side view of the multi-layer formed lens showing a modified example. Detailed implementation mode

[0037] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Among them, in all the drawings in this specification, the corresponding parts or the parts having the same function are labeled with the same reference numerals, and the following description is appropriately omitted in the repeated parts.

[0038] Figure 1 The multi-layer molded lens 5 shown is a thick-walled lens with a maximum wall thickness of 12 mm or more, which is suitably used in vehicle headlights and the like according to the required light condensing characteristics. When molding such a thick-walled plastic lens by a single layer as an existing molding method, the sink marks (minute recesses) generated in the maximum wall thickness portion have a great influence on the optical characteristics. Therefore, by introducing multi-layer molding, the maximum wall thickness can be divided and allocated to each layer. In addition to shortening the cooling time and improving the production efficiency due to the reduction of the wall thickness of each layer, the generation of sink marks is suppressed, and a thick-walled lens with good optical characteristics can be manufactured. The effect becomes significant in multi-layer molding of three layers (N = three) or more.

[0039] The multi-layer molded lens 5 exemplified as a four-layer lens is suitably manufactured by Figure 6 the molding device and the die device shown. The die device is composed of a first cavity block 7 and a second cavity block 8 that are clamped at the clamping surface 25, and laminar molding of the four-layer (N = four) multi-layer molded lens 5 is performed. The first cavity block 7 and the second cavity block 8 are respectively mounted on a fixed platen 6 and a movable platen 9 that are a clamping device via a template. The movable platen 9 moves forward and backward relative to the fixed platen 6, causing the first cavity block 7 to abut against the second cavity block 8 at the clamping surface 25 and cooperating with the fixed platen 6 to be clamped tightly. The nozzle 28 of the injection device 27 abuts against the end surface on the fixed platen 6 side of the first cavity block 7, and the molten resin generated in the injection device 27 is injected into the die device. The injection molding machine is constituted by the clamping device, the die device, and the injection device 27.

[0040] As Figures 6 - 11 shown, when the first cavity block 7 and the second cavity block 8 are respectively clamped through the clamping surface 25, at each vertex of the regular pentagon, five pairs of cavities are formed as two cavities in a radial pattern. Therefore, the reference numerals in the drawings only illustrate the outer cavities, and hereinafter, the description of the inner cavities is omitted.

[0041] As Figure 7 shown, the second cavity block 8 is arranged such that the center of the runner 11r connecting the two cavity surfaces 16 on its clamping surface 25 becomes each vertex of the regular pentagon. The second cavity block 8 is rotated 72 degrees in the direction of the arrow by a motor 26 and a belt 10 in each molding cycle. All the cavity surfaces 16 are engraved on the clamping surface 25 with the same shape and size.

[0042] As Figure 8As shown, in order to close the mold with the cavity surfaces 16 of the first cavity block 7 and the second cavity block 8 facing each other, the cavity surfaces 17, 18, 18c, and 19 are sequentially engraved and arranged along the rotation direction of the second cavity block 8. Among them, the cavity surface of the first layer recorded at the top is not engraved because it is formed by the mold closing surface 25. In addition, the cavity surface 18c is engraved in the same shape and size as the cavity surface 18, and is for the cooling cavity and does not have the grooves for the runner 13r and the gate 13g.

[0043] The depths of the cavity surfaces 17, 18, and 19 from the mold closing surface 25 are engraved in a manner that gradually becomes deeper in sequence.

[0044] As Figure 6 shown, the cavity 21 for the first layer is formed by the cavity surface 16 and the mold closing surface 25. As Figures 7 - 9 shown, the cavity 22 for the second layer is formed by the mold closing surface 25 and the cavity surface 17. As Figure 7 , Figure 8 and Figure 10 shown, the cavity 23 for the third layer is formed by the cavity surface 17 and the cavity surface 18. As Figure 7 , Figure 8 and Figure 11 shown, the cavity 24 for the fourth layer is formed by the cavity surface 18 and the cavity surface 19.

[0045] In the cavity 21, the molten resin is injected and filled via the nozzle 28 of the injection device 27, the hot runner 29, the passage for the sprue 15, the passage for the runner 11r, and the passage for the gate 11g. As a result, Figure 2 shown, the intermediate molded body 31 as the first layer 1 (thick solid line) is molded by the mold device.

[0046] In the cavity 22 formed by the transfer of the intermediate molded body 31 by the rotation of the second cavity block 8, the molten resin is injected and filled via the nozzle 28 of the injection device 27, the hot runner 29, the passage for the sprue 15, the passage for the runner 12r, and the passage for the gate 12g. As a result, Figure 3 shown, the intermediate molded body 32 including the intermediate molded body 31 (thin solid line) and the second layer 2 (thick solid line) is integrally molded by the mold device.

[0047] In the cavity 23 formed by the transfer of the intermediate molded body 32 by the rotation of the second cavity block 8, the molten resin is injected and filled via the nozzle 28 of the injection device 27, the hot runner 29, the passage for the sprue 15, the passage for the runner 13r, and the passage for the gate 13g. As a result, Figure 4 shown, the intermediate molded body 33 including the intermediate molded body 32 (thin solid line) and the third layer 3 (thick solid line) is integrally molded by the mold device.

[0048] In the cavity 24 formed by transferring the intermediate molded body 33 through the rotation of the second cavity block 8, molten resin is injected and filled via the nozzle 28 of the injection device 27, the hot runner 29, the runner 15 passage, the runner 14r passage, and the gate 14g passage. As a result, Figure 5 The completed molded body 34 shown, which includes the intermediate molded body 33 (thin solid line) and the fourth layer 4 (thick solid line), is integrally molded by the mold device.

[0049] The hot runner 29 is a runner that maintains the molten resin existing therein in a molten state by heating with a heater (not shown). The hot runner 29 opens and closes the valve that mechanically or thermally operates the nozzle portions provided at their respective front ends and abutting against the runner 15 to allow the molten resin to flow or be cut off. In the method of mechanically opening and closing the nozzle portions, since there is a concern about foreign matter generated from the movable parts, the thermally opening and closing method is preferred in lens molding.

[0050] The injection and filling for the first layer 1 into the cavity 21, the injection and filling for the second layer 2 into the cavity 22, the injection and filling for the third layer 3 into the cavity 23, and the injection and filling for the fourth layer 4 into the cavity 24 are performed simultaneously. In addition, the transfer of the intermediate molded body 31, the intermediate molded body 32, and the intermediate molded body 33 is also performed simultaneously by the rotation of the second cavity block 8.

[0051] As Figure 5 shown, for the completed molded body 34 including the first layer 1, the second layer 2, the third layer 3, and the fourth layer 4, its gates 11g, 12g, 13g, and 14g are cut off on the lens side surface 30. The completed molded body 34 after the gates 11g, 12g, 13g, and 14g are cut off, when observed in the I-I direction view of Figure 5 , becomes Figure 1 the multi-layer molded lens 5 shown. Gate marks 11t, 12t, 13t, and 14t, which are the cut-off marks of the gates 11g, 12g, 13g, and 14g, appear on the lens side surface 30 provided on the side of the lens optical axis L of the multi-layer molded lens 5. The outer surface that is the lower surface of the first layer 1 and the outer surface that is the upper surface of the fourth layer 4 are lens surfaces 50 that intersect the lens optical axis L, and are connected by the lens side surface 30 respectively. That is, as Figure 1 shown, the multi-layer molded lens 5 is a plano-convex lens having a pair of lens surfaces 50 that intersect the lens optical axis L, with the first layer 1 side forming the lower surface being a flat surface and the fourth layer 4 side forming the upper surface being a curved surface. In addition, the lens side surface 30 provided between the pair of lens surfaces 50 on the side of the lens optical axis L is a flat surface parallel to the lens optical axis L.

[0052] The cross-sectional shapes of the runners 11r, 12r, 13r, and 14r, and the gates 11g, 12g, 13g, and 14g are square. The gates 11g, 12g, 13g, and 14g are side gates perpendicular to the lens side surface 30.

[0053] The runners 11r, 12r, 13r, and 14r connected to the gates 11g, 12g, 13g, and 14g, which are side gates, can leave foreign matters such as cold material flowing in from the hot runner 29. Furthermore, foreign matters such as cold material do not flow into the cavities 21, 22, 23, and 24 of the multi-layer molded lens 5, so that a multi-layer molded lens 5 with good optical characteristics can be molded.

[0054] The runners 12r and 13r, and the gates 12g and 13g for the second layer 2 and the third layer 3 which are the inner surface layers of the lens are arranged side by side in the central portion in the width direction of the lens side surface 30. In addition, the runners 12r and 13r arranged side by side, and the gates 12g and 13g arranged side by side are adjacent to the runners 11r and 14r, and the gates 11g and 14g in the thickness direction of the lens side surface 30 to form a stacked state.

[0055] The gates 11g and 14g for the first layer 1 and the fourth layer 4 which are the outer surface layers of the lens are arranged adjacent to the gates 12g and 13g arranged side by side in the central portion in the width direction of the lens side surface 30, and a gate group is formed by the four. That is, in the central portion in the width direction of the lens side surface 30, a gate mark group is formed by integrating the traces of the side gates 11g, 12g, 13g, and 14g of the first layer to the fourth layer, namely the gate marks 11t, 12t, 13t, and 14t.

[0056] In this way, by providing a gate group in the central portion in the width direction of the lens side surface 30, the molten resin can flow evenly to each corner of each lens layer cavity for filling, so that a multi-layer molded lens 5 with excellent optical characteristics can be obtained. In addition, by integrating the gate group, the structure of the mold device can be simplified and the gate cutting can be performed once, so that the gate cutting process can be simplified.

[0057] There are two gates, namely the gates 12g and 13g, arranged side by side in the width direction of the central portion in the width direction of the lens side surface 30. However, in order to arrange a gate group in the central portion in the width direction of the lens side surface 30, it is preferable that the number of gates arranged side by side in this direction is three or less. For example, when the multi-layer molded lens is composed of five layers from the first layer to the fifth layer, two or three gates can also be arranged side by side among the gates of the second layer to the fourth layer.

[0058] At the center in the width direction of the lens side surface 30, the gate mark 11t of the first layer 1 having the largest cross-sectional area among the four layers is disposed at the bottom edge of the lens side surface 30. At the upper edge in the thickness direction of the lens side surface 30 of the gate mark 11t, the gate mark 12t of the second layer 2 and the gate mark 13t of the third layer 3 having a smaller cross-sectional area than the gate mark 14t of the fourth layer 4 are adjacent by being arranged side by side. At the upper edge in the thickness direction of the lens side surface 30 of the gate mark 12t of the second layer 2 and the gate mark 13t of the third layer 3 arranged side by side, the gate mark 14t of the fourth layer 4 having a width smaller than the width obtained by summing the widths of the gate mark 12t of the second layer 2 and the gate mark 13t of the third layer 3 is adjacently arranged. Thus, the gate mark group formed by the gate mark 11t, the gate mark 12t, the gate mark 13t, and the gate mark 14t has a shape corresponding to the shape of the lens side surface 30 (for example, a pyramid shape). The total thickness Tg of the gate marks 11t, 12t (13t), and 14t is preferably 3 to 10 mm. When the total thickness Tg of the gate is less than 3 mm, the thickness required for the two gates for the lens outer surface layer disposed at the center in the width direction of the lens side surface 30 cannot be ensured, and injection and filling into the cavity become difficult. In addition, when the total thickness Tg of the gate exceeds 10 mm, a large force is required for gate cutting, and an overly large gate cutting device is needed.

[0059] The first layer 1 and the fourth layer 4 as the lens outer surface layer are formed by side gates having a relatively large cross-sectional area, whereby the molding pressure of the molten resin can be uniformly transmitted in the cavity with a low pressure loss. Therefore, the shape of the cavity surface can be faithfully transferred and molded in the first layer 1 and the fourth layer 4 as the outer surface layer, and thus a multi-layer molded lens 5 having good optical characteristics can be molded. In addition, since the volume of the first layer 1 is relatively large, the gate 11g having the largest cross-sectional area among the four layers is effectively used.

[0060] The second layer 2 and the third layer 3 as the lens inner surface layer have a relatively small cross-sectional area and are formed by side gates arranged side by side in the width direction at the center in the width direction of the lens side surface 30. The second layer 2 and the third layer 3 are arranged side by side in order to arrange the gates 11g and 14g of the first layer 1 and the fourth layer 4 as the lens outer surface layer as close to the center as possible in the width direction of the lens side surface 30. In the inner surface layer, since the cross-sectional area of its gate is relatively small, transfer defects caused by the gate position being slightly deviated from the center in the width direction of the lens side surface 30, unevenness of the viscosity of the molten resin, etc. are melted during the molding of the next layer, and thus do not become problems.

[0061] As Figure 11As shown, the fourth layer 4 is configured such that the maximum thickness T4 of the cavity 24 is smaller than the maximum thickness T3 of the cavity 23 for the third layer 3. Thus, the maximum thickness of the fourth layer 4 (the Nth layer) is smaller than the maximum thickness of the third layer (the (N - 1)th layer). By configuring in this way, problems such as sink marks caused by insufficient cooling of the fourth layer 4, which has the shortest cooling time compared to other layers in the molding cycle, can be alleviated, and a multilayer molded lens 5 with excellent optical characteristics can be obtained.

[0062] In addition, the maximum thickness T4 of the cavity 24 for the fourth layer 4 is set to the smallest possible value at which the molten resin can easily flow in the cavity 24, and is preferably 2 to 4 mm.

[0063] In a headlight of a vehicle or the like to which the multilayer molded lens 5 is applied, in order to improve color bleeding near the light and dark boundary line in a specified light distribution pattern or to impart a blurring effect, it is sometimes required to provide a micro uneven shape on the lens surface. When the fourth layer 4 is molded, the molten resin transfers the micro unevenness 20 on the cavity surface 19, and a micro uneven shape is formed on the lens surface formed by the fourth layer 4.

[0064] As Figure 12 、 Figure 13 shown, the micro unevenness 20 is composed of countless unevennesses of several micrometers to several millimeters in a shape that is similar to a half-wave rectified wave shape or a sine wave shape in a cross-sectional view, for example. The micro unevenness 20, which is usually called a texture, is provided on the entire surface or a part of the cavity surface 19 for the fourth layer 4. In addition, when the micro unevenness 20 is provided only on one cavity surface 19 for the fourth layer 4, the manufacturing cost is several million yen. On the other hand, according to the structure of the mold device for providing the micro unevenness on the first layer, it is necessary to provide the micro unevenness on the cavity surfaces for all layers including the cooling cavity, so the cost is five times that of several million yen.

[0065] The cooling cavity is formed by the cavity surface 18c and the cavity surface 16. The cooling cavity is the same as the cavity formed by the cavity surfaces 18 and 16 for molding the intermediate molded body 33. Therefore, the cooling cavity can cool the intermediate molded body 33.

[0066] It is very effective to provide the cooling cavity for cooling the fourth layer 4 with the shortest cooling time. However, when a micro uneven shape is provided on the fourth layer 4, the cooling cavity presses the completed molded body 34 having the micro uneven shape again, and the micro uneven shape is deformed. To avoid this, it is preferable to provide the cooling cavity on the third layer 3, which is the layer immediately before the final layer. As a result, the cooling of the third layer 3 is sufficiently performed, the layer shape is stable without deforming the micro uneven shape, and thus the optical characteristics of the lens are improved.

[0067] As can be seen from the above description, the multi-layer molded lens 5 with three or more layers (N layers) includes: a pair of lens surfaces 50 that intersect the lens optical axis L, and a lens side surface 30 disposed between the pair of lens surfaces 50 on the side of the lens optical axis L. At the central portion in the width direction of the lens side surface 30, there is formed a gate mark group in which the side gate marks of each layer from the first layer to the Nth layer, that is, N gate marks 11t to 14t, are integrated.

[0068] The multi-layer molded lens is molded by injecting molten resin into the cavities for molding the first layer and the Nth layer that form a pair of lens surfaces respectively from the side gates, and the cavities for molding the second layer to the (N−1)th layer that form the inside of the lens. At the central portion in the width direction of the lens side surface, there are formed the side gate marks of each layer from the first layer to the Nth layer, that is, N gate marks. Thus, the multi-layer molded lens is filled by the molten resin with low pressure loss and no foreign matter mixed therein flowing evenly into every corner of the cavity, and the viscosity of the molten resin in the cavity becomes uniform for molding, so that it has the excellent effect of having excellent optical characteristics. In addition, the gate cutting is performed in a state where the side gates of each layer from the first layer to the Nth layer are integrated, and a gate mark group in which N gate marks are integrated is formed. Thus, the cutting of the N side gates from the first layer to the Nth layer becomes extremely easy, and it has the excellent effect of reducing the manufacturing cost.

[0069] In addition, the present disclosure includes contents that can be implemented in a manner in which various changes, corrections, improvements, etc. are added based on the knowledge of those skilled in the art. Needless to say, the embodiments with the above-mentioned changes, etc. are all included in the scope of the present disclosure as long as they do not deviate from the gist of the present disclosure.

[0070] For example, the case where the gates arranged side by side at the central portion in the width direction of the lens side surface 30 are for the inner surface layer of the lens, that is, the second layer 2 and the third layer 3 ((N−1)th layer), has been described, but it may also be configured to include the gates for the first layer 1 or the fourth layer 4 (Nth layer) that is the outer surface layer of the lens.

[0071] In addition, the case where there are two gates arranged side by side at the central portion in the width direction of the lens side surface 30 has been described, but the gates arranged side by side in a specified multi-layer may be one. For example, when the multi-layer molded lens is composed of five layers from the first layer to the fifth layer, two or three of the gates of the second layer to the fourth layer may also be arranged side by side.

[0072] In addition, the shape of the multi-layer molded lens is not limited to the above-described shape and can be any shape. For example, in the above-described embodiment, an example of a plano-convex lens is shown, but it can also be a biconvex lens in which both lens surfaces 50 are formed as curved surfaces, or it can be a concave lens. Further, although the lens side surface 30 is illustrated as a flat surface, it can also be a curved surface.

[0073] In addition, the multi-layer molded lens may be provided with a flange portion that protrudes in a flange shape radially outward around the lens surface 50, and the outer peripheral surface of the flange portion may also be in the shape of the lens side surface 30. Figure 14 FIG. is a side view of a multi-layer molded lens 105 showing a modified example, and the same reference numerals are given to the same components as in the above-described embodiment. In the multi-layer molded lens 105 having a flange portion 40 in this modified example, at the center in the width direction of the lens side surface 30 that forms the outer peripheral surface of the flange portion 40, there is formed a gate mark group in which the traces of the side gates of each layer from the first layer to the Nth layer, that is, N gate marks (11t to 14t), are integrated.

[0074] In addition, although the gates 11g, 12g, 13g, and 14g are shown as gates perpendicular to the lens side surface 30, they may not be perpendicular depending on the shape of the lens side surface 30.

[0075] In addition, although the cross-sectional shape of the gate is shown as a square, the surface that does not adjoin other gates may not be a flat surface, but may be, for example, a curved surface or a trapezoidal surface.

[0076] Description of Reference Numerals

[0077] 1... first layer; 2... second layer; 3... third layer; 4... fourth layer; 5... multi-layer molded lens (embodiment); 7... first cavity block; 8... second cavity block; 11g, 12g, 13g, 14g... gates; 11r, 12r, 13r, 14r... runners; 11t, 12t, 13t, 14t... gate marks; 16, 17, 18, 19... cavity surfaces; 20... minute unevenness; 21, 22, 23, 24... cavities; 25... mold clamping surface, 30... lens side surface; 50... lens surface; L... optical axis; T3... maximum thickness of the cavity for the third layer; T4... maximum thickness of the cavity for the fourth layer; Tg... total thickness of the gates; 105... multi-layer molded lens (modified example).

Claims

1. A multi-layer molded lens, with N layers, N≥3, characterized in that Comprising: A pair of lens surfaces that intersect with the lens optical axis; and Lens side surfaces that are disposed between the pair of lens surfaces on the side of the lens optical axis, On the lens side surfaces, N gate marks are formed, and the N gate marks are traces of side gates of respective layers from the first layer to the Nth layer. The first layer to the Nth layer are arranged in sequence along the lens optical axis direction from one surface of the pair of lens surfaces to the other surface, and are arbitrarily assigned when they are at the same position in the lens optical axis direction, By performing gate cutting in a state where the side gates of respective layers from the first layer to the Nth layer are integrated, a gate mark group formed by integrating the N gate marks is formed.

2. The multi-layer molded lens according to claim 1, wherein The gate mark of the first layer has the largest cross-sectional area among the N gate marks.

3. The multi-layer molded lens according to claim 1 or 2, wherein The gate marks of a specified multi-layer among the first layer to the Nth layer are arranged side by side along the width direction of the lens side surface as a specified one direction that intersects with the lens optical axis.

4. The multi-layer molded lens according to claim 3, wherein The gate marks of the specified multi-layer arranged side by side are the gate marks of any multi-layer among the second layer to the N-1th layer.

5. The multi-layer molded lens according to any one of claims 1 to 4, wherein The thickness of the gate mark group in the lens optical axis direction is 3 to 10 mm.

6. The multi-layer molded lens according to any one of claims 1 to 5, wherein The maximum thickness of the Nth layer is smaller than the maximum thickness of the N-1th layer.

7. The multi-layer molded lens according to any one of claims 1 to 6, wherein The maximum thickness of the Nth layer is 2 to 4 mm.

8. The multi-layer molded lens according to any one of claims 1 to 7, wherein The outer surface of the Nth layer has a micro uneven shape.

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