JP2020019227A - Multilayer molded lens - Google Patents

Abstract

To provide a multilayer molded lens with excellent optical properties obtained by uniformly injecting and filling a low-pressure-loss molten resin free of foreign matter.SOLUTION: A multilayer molded lens 5 having three or more layers (N layers) has a pair of lens faces 50 intersecting a lens optical axis L and a lens side face 30 provided between the pair of lens face 50 on the side of the lens optical axis L. At a center in a width direction of the lens side face 30, a gate trace group in which N gate traces 11t to 14t, which are traces of the side gates of a first to N-th layers, is formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a multilayer molded lens formed by injection molding.

  Multi-layer molding is, for example, as disclosed in Patent Document 1, in which an intermediate molded product as a first layer molded by a mold cavity having a minimum volume among a plurality of mold cavities having mutually different volumes has a larger volume. The second layer is transferred to the mold cavity to form the second layer, and then the intermediate molded product is sequentially transferred to each mold cavity up to the Nth layer to form the layers. 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 the respective layers from the second layer to the (N-1) th layer are provided on the lens surface.

JP 2013-107229 A

  However, since the gates of the respective layers 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 slugs, flow marks, and jetting. May not be completely melted in the formation of the next layer, and may remain as haze-like foreign matters that deteriorate optical characteristics. Further, since there is no sprue or runner, foreign matter may flow directly into the cavity from the hot runner.

  Further, according to the molding process according to the technique of Patent Document 1, the integrated cooling time of each layer is shorter for higher layers. That is, the cooling time of the N-th layer is shorter than the cooling time of any other layers. Since the N-th layer, which is the outer surface of the lens, cannot be sufficiently cooled, the surface of the N-th layer, which is optically important, sinks, leaving a minute concave portion. As a result, the optical characteristics of the lens deteriorate. To solve this problem, the cooling time of the N-th layer had to be extended, and a delay in the molding time was inevitable.

  The present invention has been made in view of the above-described problems, and has as its object to provide a multilayer molded lens having excellent optical characteristics obtained by uniformly injecting and filling a low-pressure-loss molten resin without inclusion of foreign matter. And

  The invention according to claim 1, which has been made to achieve the above object, is a multilayer molded lens having three or more layers (N layers), wherein a pair of lens surfaces intersecting a lens optical axis, A lens side surface provided between the pair of lens surfaces on the side, and N number of traces of side gates of each layer from the first layer to the Nth layer are provided at the center in the width direction of the lens side surface. That is, a gate mark group in which the gate marks are integrated is formed.

  According to this configuration, the multilayer molded lens forms the (N-1) th layer from the cavity forming the first layer and the Nth layer forming the pair of lens surfaces and the second layer forming the inside of the lens. The molding is performed by injecting molten resin from the side gates into the cavities, and N gate marks, which are marks of the side gates of the first to Nth layers, are formed at the center in the width direction of the lens side surface. Have been. Therefore, the multilayer molded lens is excellent in that the molten resin with low pressure loss without foreign matter is uniformly flowed and filled into the corners of the cavity, and the molten resin in the cavity is molded with uniform viscosity. An excellent effect of having excellent optical characteristics is exhibited. In addition, the gate cut is performed in a state where the side gates of the respective layers from the first layer to the N-th layer are integrated, and a gate mark group in which N gate marks are integrated is formed. Therefore, it is very easy to cut the N side gates from the first layer to the Nth layer, and it is possible to reduce the manufacturing cost.

  The invention according to claim 2 is that the gate mark of the first layer has the largest cross-sectional area among the N gate marks.

  According to this configuration, since the cavity for the first layer, which has a relatively large volume and forms the lens surface, is evenly filled and molded with the molten resin having a very low pressure loss, the optical characteristics of the lens are further improved. The effect is excellent.

  According to a third aspect of the present invention, gate marks of predetermined plural layers among the first layer to the Nth layer are arranged in parallel in a width direction of the lens side surface.

  According to this configuration, since the gate traces of the predetermined plural layers are arranged in parallel in the width direction of the lens side surface, the thickness of the entire gate trace group can be suppressed to be small, and the side gate group can be easily cut. As a result, there is an excellent effect that the manufacturing cost can be reduced.

  The invention according to claim 4 is that the gate traces of the predetermined plurality of layers arranged in parallel are gate traces of any of the second to (N-1) th layers. is there.

  According to this configuration, the gate traces of any of the second to (N-1) th layers forming the inside of the lens are arranged in parallel in the width direction of the side surface of the lens. The side gates of the cavities for the first layer and the N-th layer, which directly affect the quality and the optical characteristics, can be arranged at the center of the lens side surface as much as possible, and the appearance quality and the optical characteristics of the lens are improved. It works.

  According to a fifth aspect of the present invention, the total thickness of the gates stacked in the optical axis direction of the lens is 3 to 10 mm.

  According to this configuration, the side gates of the cavities for the first layer and the N-th layer which form the lens surface which directly affects the appearance quality and the optical characteristics of the lens are arranged at the center of the lens side surface as much as possible, There is an excellent effect that the cutting of the side gate group is facilitated and the manufacturing cost can be reduced.

  The invention according to claim 6 is that the maximum thickness of the N-th layer is smaller than the maximum thickness of the (N-1) -th layer.

  According to this configuration, in the multilayer molded lens, since the maximum thickness of the Nth layer is smaller than the maximum thickness of the (N-1) th layer, the cooling time is the shortest in the molding cycle as compared with the other layers. An excellent effect is obtained in that problems such as sink marks due to insufficient cooling of the N-th layer are reduced, and the optical characteristics of the lens are improved.

  According to a seventh aspect of the present invention, the maximum thickness of the N-th layer is 2 to 4 mm.

  According to this configuration, the maximum thickness of the N-th layer is 2 to 4 mm, and since the molten resin easily flows in the cavity to form the N-th layer, the optical characteristics of the lens are improved. It has the effect.

  An eighth aspect of the present invention is that the outer surface of the N-th layer has fine irregularities.

  According to this configuration, of the cavities for the first layer to the Nth layer, fine irregularities are formed only on the cavity surface for the Nth layer and molded, whereby a fine irregular shape can be formed on the lens surface. Therefore, there is an excellent effect that a multilayer molded lens having a desired optical effect such as a blurring effect can be manufactured at a relatively low cost.

It is a perspective view which shows the multilayer molded lens of this invention with the II arrow of FIG. It is a perspective view which shows the 1st layer in a multilayer molded lens as an intermediate molded object. It is a perspective view which shows the 2nd layer in a multilayer molded lens as an intermediate molded object for a 3rd layer with the intermediate molded object of a 1st layer. It is a perspective view which shows the 3rd layer in a multilayer molded lens with an intermediate molded object containing a 1st layer and a 2nd layer as an intermediate molded object for a 4th layer. It is a perspective view which shows a 4th layer in a multilayer molded lens as a completed molded object with the intermediate molded object containing a 1st layer, a 2nd layer, and a 3rd layer. FIG. 9 is a partial cross-sectional side view of a molding device and a mold device for simultaneously manufacturing each of the multilayer molded lenses including the first to fourth layers, as viewed from arrows VI-VI in FIGS. 7 and 8. It is a front view which shows the mold-matching surface of the 2nd cavity block in a metal mold | die apparatus. It is a front view which shows the mold-matching surface of the 1st cavity block in a metal mold | die apparatus. FIG. 9 is a cross-sectional side view showing a second-layer molding cavity of the mold apparatus as viewed in the direction of arrows IX-IX in FIGS. 7 and 8. FIG. 10 is a cross-sectional side view showing a third-layer molding cavity of the mold apparatus as viewed in the direction of arrows XX in FIGS. 7 and 8. FIG. 9 is a cross-sectional side view showing a fourth-layer molding cavity of the mold apparatus as viewed in the direction of arrows XI-XI in FIGS. 7 and 8. FIG. 4 is a partially enlarged sectional view of a cavity surface showing a shape of fine irregularities. It is a partial expanded sectional view of a cavity surface showing other shapes of fine unevenness. It is a side view which shows the multilayer molded lens of a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in all the drawings in this specification, parts that correspond to each other or parts that have similar functions are denoted by the same reference numerals, and descriptions of overlapping parts will be omitted as appropriate.

  The multilayer molded lens 5 shown in FIG. 1 is suitably used for a headlight of a vehicle or the like, and becomes a thick lens having a maximum thickness of 12 mm or more depending on required light-collecting characteristics. When such a thick plastic lens is molded in a single layer as a conventional molding method, sink marks (micro concave portions) generated in the thickest portion greatly affect the optical characteristics. Therefore, by introducing multi-layer molding, the maximum thickness can be divided and distributed to each layer, which reduces the thickness of each layer, shortens cooling time, improves production efficiency, and suppresses sink marks. As a result, a thick lens with good optical characteristics can be manufactured. This effect is remarkable in multilayer molding of three or more layers (N = 3).

  The multilayer molded lens 5 exemplified as a four-layer one is suitably manufactured by a molding apparatus and a mold apparatus shown in FIG. The mold apparatus is composed of a first cavity block 7 and a second cavity block 8 to be mold-matched on a mold-matching surface 25, and laminate-molds a four-layer (N = 4) multilayer molded lens 5. The first cavity block 7 and the second cavity block 8 are respectively attached to a fixed platen 6 and a movable platen 9 which are mold clamping devices via a mold plate. The movable platen 9 moves forward and backward with respect to the fixed platen 6 so that the first cavity block 7 and the second cavity block 8 abut on the mold mating surface 25 and cooperate with the fixed platen 6 to crush. The nozzle 28 of the injection device 27 comes into contact with the end surface of the first cavity block 7 on the fixed platen 6 side, and the molten resin generated by the injection device 27 is injected into the mold device. An injection molding machine is constituted by the mold clamping device, the mold device, and the injection device 27.

  As shown in FIGS. 6 to 11, when each of the first cavity block 7 and the second cavity block 8 is mold-matched on the mold-matching surface 25, five pairs of cavities are formed at each apex of the regular pentagon as radiation. Formed on top. Therefore, the reference numerals in the drawings are given only to the outer cavity, and the description of the inner cavity will be omitted.

  As shown in FIG. 7, the second cavity block 8 is disposed on the mold matching surface 25 such that the center of the runner 11r groove connecting the two cavity surfaces 16 is each vertex of a regular pentagon. The second cavity block 8 is rotated by the motor 26 and the belt 10 in the direction of the arrow 72 degrees every molding cycle. All the cavity surfaces 16 are engraved on the mold matching surface 25 with the same shape and dimensions.

  As shown in FIG. 8, the cavity surface 17, the cavity surface 18, the cavity surface 18 c, and the cavity surface 19 are arranged such that the first cavity block 7 can be matched with the respective cavity surfaces 16 of the second cavity block 8 so as to be moldable. They are engraved and arranged in the rotation direction of the second cavity block 8 in this order. However, since the cavity surface for the first layer described at the top is formed by the mold matching surface 25, it is not engraved. The cavity surface 18c is engraved with the same shape and size as the cavity surface 18 and is for a cooling cavity and does not have a groove for the runner 13r and the gate 13g.

  The depths of the cavity surface 17, the cavity surface 18, and the cavity surface 19 from the mold matching surface 25 are engraved so as to gradually increase in this order.

  As shown in FIG. 6, the first layer cavity 21 is formed by the cavity surface 16 and the mold mating surface 25. As shown in FIGS. 7 to 9, the second layer cavity 22 is formed by the mold matching surface 25 and the cavity surface 17. As shown in FIGS. 7, 8 and 10, the third layer cavity 23 is formed by the cavity surface 17 and the cavity surface 18. As shown in FIGS. 7, 8 and 11, the fourth layer cavity 24 is formed by the cavity surface 18 and the cavity surface 19.

  The cavity 21 is injected and filled with the molten resin 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, the intermediate molded body 31 as the first layer 1 (thick solid line) shown in FIG. 2 is molded by the mold device.

  In the cavity 22 formed by transferring the intermediate molded body 31 by the rotation of the second cavity block 8, 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 are provided. The molten resin is injected and filled via the resin. As a result, the intermediate molded body 32 including the intermediate molded body 31 (thin solid line) and the second layer 2 (thick solid line) shown in FIG. 3 is integrally molded by the mold device.

  The nozzle 23 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 are provided in the cavity 23 formed by transferring the intermediate molded body 32 by the rotation of the second cavity block 8. The molten resin is injected and filled via the resin. As a result, the intermediate molded body 33 including the intermediate molded body 32 (thin solid line) and the third layer 3 (thick solid line) shown in FIG. 4 is integrally molded by the mold device.

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

  The hot runner 29 is a runner that keeps the molten resin existing therein in a molten state by keeping the temperature of the molten resin by a heater (not shown). The hot runners 29 open and close the nozzles provided at the respective ends, which are in contact with the sprues 15, by a valve that operates mechanically or thermally to flow or shut off the molten resin. In the method of mechanically opening and closing the nozzle portion, there is a possibility that foreign matter may be generated from the movable portion. Therefore, in the lens molding, the method of thermally opening and closing the nozzle is preferable.

  Injection and filling of cavity 21 for first layer 1, injection and filling of cavity 22 for second layer 2, injection and filling of cavity 23 for third layer 3, and fourth layer for cavity 24 The injection and filling for 4 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 simultaneously executed by the rotation of the second cavity block 8.

  As shown in FIG. 5, the completed molded body 34 including the first layer 1, the second layer 2, the third layer 3, and the fourth layer 4 has the gates 11g, 12g, 13g, and 14g cut at the lens side surface 30. You. The completed molded body 34 from which the gates 11g, 12g, 13g, and 14g have been cut becomes the multilayer molded lens 5 shown in FIG. Gate marks 11t, 12t, 13t, and 14t, which are cut 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 multilayer molded lens 5. The outer surface as the lower surface of the first layer 1 and the outer surface as the upper surface of the fourth layer 4 are lens surfaces 50 that intersect the lens optical axis L, and are connected by lens side surfaces 30, respectively. That is, as shown in FIG. 1, the multilayer molded lens 5 includes a pair of lens surfaces 50 intersecting with the lens optical axis L, the lower surface of the first layer 1 being a flat surface, and the upper surface of the fourth layer 4 being an upper surface. The side is a plano-convex lens having a curved surface. 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.

  The cross sections of the runner 11r, the runner 12r, the runner 13r and the runner 14r, and the gate 11g, the gate 12g, the gate 13g and the gate 14g are square. The gate 11g, the gate 12g, the gate 13g, and the gate 14g are side gates perpendicular to the lens side surface 30.

  The runner 11r, the runner 12r, the runner 13r and the runner 14r connected to the gate 11g, the gate 12g, the gate 13g and the gate 14g, which are side gates, can keep foreign substances such as cold slug flowing from the hot runner 29 therein. it can. Since foreign matter such as cold slug does not flow into the cavities 21, 22, 23 and 24 of the multilayer molded lens 5, the multilayer molded lens 5 having good optical characteristics can be molded.

  The runners 12r and 13r, and the gates 12g and 13g are for the second layer 3 and the third layer 3, which are the inner surface layers of the lens, and are arranged in parallel in the widthwise center of the lens side surface 30. The runners 12r and 13r arranged in parallel and the gates 12g and 13g arranged in parallel are adjacent to the runners 11r and 14r and the gates 11g and 14g in the thickness direction of the lens side surface 30. It is in a laminated state.

  The gate 11g and the gate 14g are for the first layer 1 and the fourth layer 4 which are the outer surface layers of the lens, and are arranged at the center in the width direction of the lens side surface 30 adjacent to the gates 12g and 13g arranged in parallel. People form a gate group. That is, gate marks 11t, 12t, 13t, and 14t, which are marks of the side gates 11g, 12g, 13g, and 14g of each of the first to fourth layers, are integrated at the center of the lens side surface 30 in the width direction. Groups are formed.

  As described above, by providing the gate group at the center in the width direction on the lens side surface 30, the molten resin can be uniformly flowed and filled into the corners of each lens layer cavity, and the multilayer molded lens having excellent optical characteristics can be filled. 5 can be obtained. In addition, by integrating the gate group, the structure of the mold apparatus can be simplified, and the gate cut can be performed at one time, so that the gate cut processing can be simplified.

  The gates arranged in parallel in the width direction at the center in the width direction of the lens side surface 30 are the gate 12g and the gate 13g, but in order to arrange the gate group at the center in the width direction on the lens side surface 30, Preferably, no more than three gates are arranged in parallel in this direction. For example, when the multilayer molded lens is formed of five layers from the first layer to the fifth layer, two or three of the gates of the second to fourth layers may be arranged in parallel.

  At the center in the width direction of the lens side surface 30, a gate mark 11t of the first layer 1 having the largest cross-sectional area among the four layers is arranged at the bottom of the lens side surface 30. On the upper side in the thickness direction of the lens side surface 30 of the gate trace 11t, a gate trace 12t of the second layer 2 and a gate trace 13t of the third layer 3 having a smaller cross-sectional area than the gate trace 14t of the fourth layer 4 are arranged in parallel. Adjacent. On the upper side in the thickness direction of the lens side surface 30 of the gate trace 12t of the second layer 2 and the gate trace 13t of the third layer 3 arranged in parallel, the fourth layer 4 having a width smaller than the total width thereof is provided. Gate marks 14t are arranged adjacent to each other. As described above, 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 (for example, a pyramid shape) corresponding to the shape of the lens side surface 30. The total thickness Tg of the gate trace 11t, the gate trace 12t (gate trace 13t), and the gate trace 14t is preferably 3 to 10 mm. When the total gate thickness Tg is less than 3 mm, the thickness required for two gates for the lens outer surface layer to be disposed at the center in the width direction of the lens side surface 30 cannot be secured, so that injection into the cavity is not possible. Filling becomes difficult. If the total gate thickness Tg exceeds 10 mm, a large force is required for gate cutting, and an excessively large gate cutting device is required.

  By molding the first layer 1 and the fourth layer 4 serving as the lens outer surface layers with side gates having a relatively large cross-sectional area, the molding pressure of the molten resin can be uniformly transmitted to the cavity with low pressure loss. Therefore, since 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 layers, the multilayer molded lens 5 having good optical characteristics can be molded. Further, since the first layer 1 has a relatively large volume, the gate 11g having the largest sectional area among the four layers is effectively used.

  The second layer 3 and the third layer 3 serving as the lens inner surface layers have a relatively small cross-sectional area, and are formed by side gates arranged in parallel in the width direction at the center in the width direction on the lens side surface 30. The second layer 3 and the third layer 3 are arranged in parallel because the gates 11g and 14g of the first layer 1 and the fourth layer 4 serving as the lens outer surface layers are located at the center as much as possible in the width direction of the lens side surface 30. It is for arrangement. In the inner layer, poor transfer and uneven viscosity of the molten resin due to the relatively small cross-sectional area of the gate and the slight departure of the gate position from the center in the width direction of the lens side surface 30 are caused by the molding of the next layer. There is no problem because it is melted at

  As shown in FIG. 11, the maximum thickness T4 of the fourth layer 4 cavity 24 is smaller than the maximum thickness T3 of the third layer 3 cavity 23. Thereby, the maximum thickness of the fourth layer 4 (N-th layer) becomes smaller than the maximum thickness of the third layer ((N-1) -th layer). With this configuration, problems such as sink marks due to insufficient cooling of the fourth layer 4 in which the cooling time is the shortest in comparison with the other layers on the molding cycle are reduced, and the multilayer molded lens having excellent optical characteristics is reduced. 5 can be obtained.

  The maximum thickness T4 of the cavity 24 for the fourth layer 4 is preferably 2 to 4 mm as a value as small as possible so that the molten resin can easily flow in the cavity 24.

  In a headlight of a vehicle or the like to which the multilayer molded lens 5 is applied, in order to improve color blur near a light / dark boundary line in a predetermined light distribution pattern or to impart a blurring effect, a fine uneven shape is provided on the lens surface. May be required. At the time of molding the fourth layer 4, the molten resin transfers the fine irregularities 20 on the cavity surface 19 to form fine irregularities on the lens surface molded by the fourth layer 4.

  As shown in FIGS. 12 and 13, the fine irregularities 20 are formed of, for example, innumerable irregularities of several micrometers to several millimeters having a shape similar to a half-wave rectified wave shape or a sine wave shape in a sectional view. It is. The fine unevenness 20 generally called a texture is provided on the entire surface of the cavity surface 19 for the fourth layer 4 or a part thereof. Further, the fine irregularities 20 are provided on only one cavity surface 19 for the fourth layer 4, and the production cost is several million yen. On the other hand, according to the configuration of the mold apparatus in which fine irregularities are provided on the first layer, it is necessary to provide fine irregularities on the cavity surfaces for all the layers including the cooling cavities. Will hang.

  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 molding the intermediate molded body 33 and by the cavity surface 18 and the cavity surface 16. Therefore, the cooling cavity can cool the intermediate molded body 33.

  It is effective to provide the cooling cavity for the fourth layer 4 having the shortest cooling time. However, when providing the fine irregularities on the fourth layer 4, the finished molded body 34 on which the fine irregularities are formed is pressed again in the cooling cavity, and the fine irregularities are deformed. In order to avoid this, it is preferable to provide a cooling cavity in the third layer 3 which is located just before the final layer. As a result, the third layer 3 is sufficiently cooled, and the layer shape is stabilized without deforming the fine irregularities, thereby improving the optical characteristics of the lens.

  As is clear from the above description, the multilayer molded lens 5 having three or more layers (N layers) includes a pair of lens surfaces 50 intersecting the lens optical axis L and a pair of lenses on the side of the lens optical axis L. And N lens traces 11t to 14t, which are traces of side gates of each of the first to Nth layers, at the center in the width direction of the lens side surface 30. Are formed to form a gate mark group.

  The multilayer molded lens has side gates formed in a cavity for molding the first layer and the N-th layer forming a pair of lens surfaces and a cavity for molding the (N-1) th layer from the second layer forming the inside of the lens. Are formed by injecting molten resin from each other, and N gate marks, which are marks of the side gates of the first to Nth layers, are formed at the center in the width direction of the lens side surface. Therefore, the multilayer molded lens is excellent in that the molten resin of low pressure loss without foreign matter is uniformly flowed and filled into every corner of the cavity, and the viscosity of the molten resin in the cavity is uniform, so that the multilayer molded lens is excellent. It has an excellent effect of having optical characteristics. In addition, the gate cut is performed in a state where the side gates of the respective layers from the first layer to the N-th layer are integrated, and a gate mark group in which N gate marks are integrated is formed. Therefore, it is extremely easy to cut the N side gates from the first layer to the N-th layer, and it is possible to reduce the manufacturing cost.

  It should be noted that the present invention includes those that can be implemented in modes in which various changes, modifications, improvements, and the like are made based on the knowledge of those skilled in the art. Further, it goes without saying that all the modified embodiments are included in the scope of the present invention unless they depart from the gist of the present invention.

  For example, the gates arranged in parallel at the center in the width direction of the lens side surface 30 have been described as being used for the second layer 2 and the third layer 3 ((N-1) th layer) which are the lens inner surface layers. It may be configured to include a gate for the first layer 1 or the fourth layer 4 (N-th layer) which is a layer.

  Also, although two gates are arranged in parallel at the center in the width direction of the lens side surface 30, one or a plurality of predetermined layers may be arranged in parallel. For example, when the multilayer molded lens is formed of five layers from the first layer to the fifth layer, two or three of the gates of the second to fourth layers may be arranged in parallel.

  Further, the shape of the multilayer molded lens is not limited to the one described above, and may be any shape. For example, in the above embodiment, an example of a plano-convex lens is shown, but a pair of lens surfaces 50 may be a biconvex lens having a curved surface or a concave lens. Further, the lens side surface 30 is illustrated as a flat surface, but may be a curved surface.

  Further, the multilayer molded lens may have a shape in which a flange portion is provided around the lens surface 50 so as to protrude radially outward in a flange shape, and the outer peripheral surface of the flange portion is the lens side surface 30. FIG. 14 is a side view showing a multilayer molded lens 105 of a modification, and the same members as those in the above embodiment are denoted by the same reference numerals. In the multilayer molded lens 105 having the flange portion 40 in this modified example, N marks, which are traces of the side gates of the first to Nth layers, are provided at the center in the width direction of the lens side surface 30 forming the outer peripheral surface of the flange portion 40. A gate mark group in which the gate marks (11t to 14t) are integrated is formed.

  Although the gate 11g, the gate 12g, the gate 13g, and the gate 14g are shown as being perpendicular to the lens side surface 30, they may not be vertical depending on the shape of the lens side surface 30.

  Further, although the cross-sectional shape of the gate is shown as a square, the surface that is not adjacent to other gates is not a plane but may be, for example, a curved surface or a trapezoidal surface.

DESCRIPTION OF SYMBOLS 1 1st layer 2 2nd layer 3 3rd layer 4 4th layer 5 Multilayer molded lens (embodiment)
7 First cavity block 8 Second cavity block 11g, 12g, 13g, 14g Gate 11r, 12r, 13r, 14r Runner 11t, 12t, 13t, 14t Gate mark 16, 17, 18, 19 Cavity surface 20 Fine irregularities 21, 22 , 23,24 Cavity 25 Mold matching surface 30 Lens side surface 50 Lens surface L Optical axis T3 Maximum thickness of third layer cavity T4 Maximum thickness of fourth layer cavity Tg Total gate thickness 105 Multilayer molded lens (deformation) Example)

Claims (8)

A multilayer molded lens having three or more layers (N layers),
A pair of lens surfaces intersecting the lens optical axis,
A lens side surface provided between the pair of lens surfaces on a side of the lens optical axis,
With
A multilayer molded lens in which a gate trace group in which N gate traces, which are traces of side gates in each of the first to Nth layers, are formed at the center in the width direction of the lens side surface.   The multilayer molded lens according to claim 1, wherein the gate trace of the first layer has a largest cross-sectional area among the N gate traces.   3. The multilayer molded lens according to claim 1, wherein a predetermined plurality of gate marks of the first to Nth layers are arranged in parallel in a width direction of the lens side surface. 4.   4. The multilayer molded lens according to claim 3, wherein the gate traces of the predetermined plurality of layers arranged in parallel are gate traces of any of the second to (N−1) th layers. 5.   The multilayer molded lens according to any one of claims 1 to 4, wherein the thickness of the gate mark group is 3 to 10 mm.   The multilayer molded lens according to any one of claims 1 to 5, wherein a maximum thickness of the Nth layer is smaller than a maximum thickness of the (N-1) th layer.   The multilayer molded lens according to any one of claims 1 to 6, wherein a maximum thickness of the N-th layer is 2 to 4 mm.   The multilayer molded lens according to any one of claims 1 to 7, wherein the outer surface of the N-th layer has fine irregularities.

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