CN114786907A - Multilayer molded lens - Google Patents

Abstract

The invention provides a multilayer molded lens with excellent optical characteristics, which is obtained by uniformly injecting and filling a low-pressure-loss molten resin without mixing foreign matters. A multilayer molded lens (5) having three or more layers (N layers) is provided with: a pair of lens surfaces (50) intersecting 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), wherein a gate mark group formed by integrating N gate marks (11 t-14 t), which are marks of side gates of the layers from the first layer to the Nth layer, is formed at the central part of the lens side surface (30) in the width direction.

Description

Multilayer molded lens

Technical Field

The present disclosure relates to a multilayer molded lens which is multilayer molded by injection molding.

Background

As disclosed in patent document 1, for example, in multilayer molding, an intermediate molded product of a first layer molded in a minimum volume of a plurality of mold cavities having different volumes is transferred to a mold cavity having a larger volume to laminate and mold a second layer, and then the intermediate molded product is sequentially transferred to the mold cavities up to the nth layer to laminate and mold the layers. The gates of the first and nth layers are provided on the outer peripheral end surface of the lens, and the gates of the layers from the second layer to the (N-1) th layer are provided on the lens surface.

Patent document 1: japanese patent laid-open publication No. 2013-107229

However, since the gate of each of the second to (N-1) th layers is provided on the lens surface, an irregular change in the viscosity of the molten resin due to molding failure such as cold material, wave flow mark, and radiation pattern is not completely melted by the molding of the next layer, and may remain as a colloidal foreign substance that deteriorates the optical characteristics. Further, since there is no runner or flow channel, foreign matter may flow directly from the hot runner into the cavity.

In addition, according to the molding step of the technique of patent document 1, the cumulative cooling time of each layer becomes shorter as the layer goes to the upper layer. I.e. the cooling time of the nth layer is shorter than the cooling time of any of the other layers. Further, the nth layer, which is the outer surface of the lens, cannot be sufficiently cooled, and thus the surface of the optically important nth layer shrinks to leave minute recesses. The optical characteristics of the lens are degraded. In order to solve this problem, the cooling time of the nth layer has to be extended, and a delay in the molding time cannot be avoided.

Disclosure of Invention

The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a multilayer molded lens having excellent optical characteristics, which is obtained by uniformly injecting and filling a low-pressure-loss molten resin without mixing foreign substances.

In order to achieve the above object, according to one aspect of the present disclosure, a multilayer molded lens is a multilayer molded lens having three or more layers (N layers), including: a pair of lens surfaces intersecting the lens optical axis; and a lens side surface provided between the pair of lens surfaces on a side of the optical axis of the lens, wherein a gate mark group in which N gate marks, which are marks of side gates in respective layers from the first layer to the N-th layer, are integrated is formed in a central portion in the width direction of the lens side surface.

According to the present disclosure, a multilayer molded lens is molded by injecting molten resin from a side gate into a cavity for molding a first layer and an N-th layer forming a pair of lens surfaces, and a cavity for molding from a second layer to an (N-1) -th layer in the lens, and N gate marks, which are marks of the side gate of each of the first layer to the N-th layer, are formed in a central portion in a width direction of a side surface of the lens. Thus, the multilayer molded lens has an excellent effect of having excellent optical characteristics, because the molten resin having a low pressure loss and no foreign matter mixed therein flows uniformly to each corner of the cavity and is filled therein, and the viscosity of the molten resin in the cavity is uniform and the lens is molded. Further, gate cutting is performed in a state where the side gates of the first to nth layers are integrated, and a gate mark group in which N gate marks are integrated is formed. This makes it extremely easy to cut the N side gates from the first layer to the nth layer, thereby achieving an excellent effect of reducing the manufacturing cost.

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

According to the present disclosure, since the cavity for the first layer having a relatively large volume and forming the lens surface is uniformly filled with the molten resin having an extremely low pressure loss and is molded, the excellent effect of further improving the optical characteristics of the lens is obtained.

In addition, according to another aspect of the present disclosure, the gate marks of a predetermined plurality of layers from the first layer to the nth layer of the multilayer molded lens are arranged in parallel in the width direction of the lens side surface.

According to the present disclosure, since the gate marks of the predetermined plurality of layers are arranged side by side in the width direction of the lens side surface, the thickness of the entire gate mark group can be suppressed to be small, the side gate group can be easily cut, and the excellent effect of reducing the manufacturing cost can be achieved.

In addition, according to another aspect of the present disclosure, the gate mark of the predetermined plurality of layers arranged in parallel in the multilayer molded lens is a gate mark of any of the second layer to the (N-1) th layer.

According to the present disclosure, since the gate marks forming any of the plurality of layers from the second layer to the (N-1) th layer in the lens are arranged in parallel in the width direction of the lens side surface, the side gates of the cavities for the first layer and the N-th layer, which directly affect the appearance quality and the optical characteristics of the lens, can be arranged at the most central positions of the lens side surface, which is an excellent effect of improving the appearance quality and the optical characteristics of the lens.

In addition, according to another aspect of the present disclosure, the sum total of the thicknesses of the gates stacked in the optical axis direction of the lens in the multilayer molded lens is 3 to 10 mm.

According to the present disclosure, the side gates of the cavities for forming the first and N-th layers of the lens surface, which directly affect the appearance quality and optical characteristics of the lens, are disposed at the most central positions of the lens side surfaces, and the side gate group is easily cut, thereby achieving an excellent effect of reducing the manufacturing cost.

In addition, according to another aspect of the present disclosure, the maximum thickness of the above-mentioned nth layer of the multilayer molded lens is smaller than the maximum thickness of the (N-1) th layer.

According to the present disclosure, since the maximum thickness of the nth layer is smaller than the maximum thickness of the (N-1) th layer, the multilayer molded lens reduces the problem of sink marks and the like due to insufficient cooling of the nth layer having the shortest cooling time compared to other layers in the molding cycle, thereby achieving an excellent effect of improving the optical characteristics of the lens.

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.

According to the present disclosure, the maximum thickness of the nth layer is 2 to 4mm, and the molten resin is easily flowed in the cavity to mold the nth layer, thereby achieving an excellent effect of improving the optical characteristics of the lens.

In addition, according to another aspect of the present disclosure, the multilayer molded lens has a minute uneven shape on the outer surface of the nth layer.

According to the present disclosure, the minute irregularities can be formed on the lens surface by forming the minute irregularities only on the cavity surface for the N-th layer among the cavities from the first layer to the N-th layer, and thus the excellent effect of manufacturing a multilayer molded lens having a desired optical effect such as a blur effect can be achieved at a relatively low cost.

Drawings

Fig. 1 is a perspective view illustrating a multi-layered molded lens of an embodiment by an I-I arrow of fig. 5.

Fig. 2 is a perspective view showing a first layer of a multilayer molded lens as an intermediate molded body.

Fig. 3 is a perspective view showing the second layer of the multilayer molded lens together with the intermediate molded body of the first layer as an intermediate molded body for the third layer.

Fig. 4 is a perspective view showing a third layer of the multilayer molded lens together with an intermediate molded body including the first layer and the second layer as an intermediate molded body for a fourth layer.

Fig. 5 is a perspective view showing a fourth layer of the multilayer molded lens together with an intermediate molded body including the first layer, the second layer, and the third layer as a completed molded body.

Fig. 6 is a side view, partially in cross section, showing a molding apparatus and a mold apparatus for simultaneously producing a multilayer molded lens including first to fourth layers, by arrows VI to VI in fig. 7 and 8.

Fig. 7 is a front view showing a mating face of a second cavity block in the mold apparatus.

Fig. 8 is a front view showing a mating surface of the first cavity block in the mold apparatus.

Fig. 9 is a cross-sectional side view showing a second layer molding cavity of the mold apparatus by an IX-IX arrow in fig. 7 and 8.

Fig. 10 is a cross-sectional side view showing a third layer molding cavity of the mold apparatus by an X-X arrow in fig. 7 and 8.

Fig. 11 is a cross-sectional side view showing a fourth layer molding cavity of the mold apparatus by arrows XI-XI in fig. 7 and 8.

Fig. 12 is a partially enlarged cross-sectional view of a cavity surface showing a shape of a minute unevenness.

Fig. 13 is a partially enlarged cross-sectional view of a cavity surface having another shape showing fine irregularities.

Fig. 14 is a side view of a multilayer molded lens according to a modification.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In all the drawings in the present specification, the same reference numerals are given to mutually corresponding portions or portions having the same functions, and the description thereof will be appropriately omitted in the overlapping portions.

The multilayer molded lens 5 shown in fig. 1 is a thick lens which is suitably used for a vehicle headlamp or the like, and has a maximum thickness of 12mm or more depending on the required light condensing characteristics. When such a thick plastic lens is molded by one layer as in the conventional molding method, sink marks (minute recesses) generated in the maximum thickness portion largely affect the optical characteristics. Therefore, by introducing multilayer molding, the maximum thickness can be divided and distributed to each layer, and the thickness of each layer is reduced to shorten the cooling time and improve the production efficiency, and further, the generation of sink marks is suppressed and the production of a thick lens having excellent optical characteristics can be realized. This effect is remarkable in multilayer molding of three or more layers (N).

The multilayer molded lens 5 exemplified as a four-layer lens is appropriately manufactured by a molding apparatus and a mold apparatus shown in fig. 6. The mold apparatus is composed of a first cavity block 7 and a second cavity block 8 which are clamped at a clamping surface 25, and performs laminated molding of a multilayer molded lens 5 having four layers (N is four). The first cavity block 7 and the second cavity block 8 are attached to a fixed platen 6 and a movable platen 9, respectively, which are mold clamping devices, via mold plates. The movable platen 9 is movable forward and backward with respect to the fixed platen 6, and the first cavity block 7 and the second cavity block 8 are brought into contact with each other at the mold clamping surfaces 25 and pressed in cooperation with the fixed platen 6. The nozzle 28 of the injection device 27 abuts against the end surface of the first cavity block 7 on the side of the stationary platen 6, and the molten resin produced by the injection device 27 is injected into the mold device. The injection molding machine is constituted by the mold clamping device, the mold device, and the injection device 27.

As shown in fig. 6 to 11, when the first cavity block 7 and the second cavity block 8 are clamped by the clamping surfaces 25, five pairs of cavities are formed on a radial line as two cavities at each vertex of the regular pentagon. Therefore, reference numerals in the drawings only describe the outer cavities, and description of the inner cavities will be omitted below.

As shown in fig. 7, the second cavity block 8 is disposed such that the centers of the grooves for the flow channels 11r connecting the two cavity surfaces 16 are the respective vertexes of a regular pentagon at the mating surface 25. The second cavity block 8 is rotated 72 degrees in the direction of the arrow during each molding cycle by the motor 26 and belt 10. All the cavity surfaces 16 are engraved in the mold clamping surface 25 with the same shape and size.

As shown in fig. 8, in order to allow the first cavity block 7 and the cavity surfaces 16 of the second cavity block 8 to face each other and to be clamped, a cavity surface 17, a cavity surface 18c, and a cavity surface 19 are sequentially engraved and arranged in the rotation direction of the second cavity block 8. The first-layer cavity surface described in the uppermost portion is not engraved because it is formed by the mold clamping surface 25. The cavity surface 18c is engraved so as to have the same shape and size as the cavity surface 18, and is provided with a groove for cooling the cavity and not provided with the runner 13r and the gate 13 g.

The cavity surface 17, the cavity surface 18, and the cavity surface 19 are engraved so that the depths from the mating surface 25 are gradually increased.

As shown in fig. 6, the first layer cavity 21 is formed by the cavity surface 16 and the die surface 25. As shown in fig. 7 to 9, the second-layer cavity 22 is formed by the mold clamping surface 25 and the cavity surface 17. As shown in fig. 7, 8, and 10, the third-layer cavity 23 is formed by the cavity surface 17 and the cavity surface 18. As shown in fig. 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 filled with molten resin by injection through a nozzle 28 of an injection device 27, a hot runner 29, a passage for runner 15, a passage for runner 11r, and a passage for gate 11 g. As a result, the intermediate formed body 31 as the first layer 1 (thick solid line) shown in fig. 2 is formed by the mold apparatus.

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

The molten resin is injected and filled into the cavity 23 formed by the intermediate molded body 32 being transferred by the rotation of the second cavity block 8 through the nozzle 28, the hot runner 29, the passage for the runner 15, the passage for the runner 13r, and the passage for the gate 13g of the injection device 27. 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 the intermediate molding body 33 being transferred by the rotation of the second cavity block 8, the molten resin is injected and filled through the nozzle 28 of the injection device 27, the hot runner 29, the passage for the runner 15, the passage for the runner 14r, and the passage for the gate 14 g. As a result, the finished 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 flow path for keeping molten resin present therein in a molten state while keeping the molten resin warm by a heater, not shown. The hot runner 29 causes molten resin to flow or block by opening and closing a valve that mechanically or thermally operates a nozzle portion provided at each tip and in contact with the runner 15. In the method of mechanically opening and closing the nozzle portion, since there is a possibility that foreign matter is generated from the movable portion, the method of thermally opening and closing is preferable in lens molding.

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

As shown in fig. 5, the gates 11g, 12g, 13g, and 14g of the finished molded body 34 including the first layer 1, the second layer 2, the third layer 3, and the fourth layer 4 are cut at the lens side surface 30. The completed molded body 34 having the gates 11g, 12g, 13g, and 14g cut off is a multilayer molded lens 5 shown in fig. 1 as viewed from I-I of fig. 5. Gate marks 11t, 12t, 13t, and 14t, which are cut marks of the gates 11g, 12g, 13g, and 14g, appear on a lens side surface 30 provided on a side of the lens optical axis L of the multilayer molded lens 5. The outer surface of the lower surface of the first layer 1 and the outer surface of the upper surface of the fourth layer 4 are lens surfaces 50 intersecting the lens optical axis L and are connected to each other by a lens side surface 30. That is, as shown in fig. 1, the multilayer molded lens 5 is a plano-convex lens including a pair of lens surfaces 50 intersecting the lens optical axis L, in which the first layer 1 side forming the lower surface is a flat surface and the fourth layer 4 side forming the upper surface is 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-sectional shapes 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 gates 11g, 12g, 13g, and 14g are side gates perpendicular to the lens side surface 30.

The runners 11r, 12r, 13r, and 14r connected to the gates 11g, 12g, 13g, and 14g as side gates can leave foreign matter such as cold material flowing from the hot runner 29. Further, foreign matter such as cold material does not flow into the cavity 21, the cavity 22, the cavity 23, and the cavity 24 of the multilayer molded lens 5, and thus the multilayer molded lens 5 having excellent optical characteristics can be molded.

The runners 12r, 13r, gates 12g, 13g are for the second layer 2 and the third layer 3 as the inner surface layers of the lens, and are arranged side by side at the widthwise central portion of the lens side surface 30. The flow paths 12r and 13r arranged side by side and the gates 12g and 13g arranged side by side are adjacent to the flow paths 11r and 14r, and the gates 11g and 14g in the thickness direction of the lens side surface 30 and are stacked.

The gates 11g and 14g are used for the first layer 1 and the fourth layer 4 as the outer surface layers of the lens, and are arranged adjacent to the gates 12g and 13g arranged side by side at the center in the width direction of the lens side surface 30, and a gate group is formed by the four. That is, a gate mark group in which 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 is formed in the widthwise central portion of the lens side surface 30.

By providing the gate group in the widthwise central portion of the lens side surface 30 in this manner, the molten resin can be uniformly flowed and filled into each corner of each lens layer cavity, and thus the multilayer molded lens 5 having excellent optical characteristics can be obtained. In addition, by integrating the gate groups, the structure of the mold apparatus can be simplified and the gate cutting process can be simplified by performing the gate cutting at a time.

The gates arranged side by side in the width direction of the widthwise central portion of the lens side surface 30 are two gates 12g and 13g, but in order to arrange the gate group in the widthwise central portion of the lens side surface 30, it is preferable that the number of gates arranged side by side in this direction is within three. For example, in the case where the multilayer molded lens is composed of five layers of the first to fifth layers, two or three gates may be arranged in parallel in the gates of the second to fourth layers.

The gate mark 11t of the first layer 1 having the largest cross-sectional area among the four layers is disposed on the bottom side of the lens side surface 30 in the widthwise central portion of the lens side surface 30. Gate mark 12t of second layer 2 and gate mark 13t of third layer 3, which have a smaller cross-sectional area than gate mark 14t of fourth layer 4, are adjacent to each other by being arranged side by side at the upper edge of gate mark 11t in the thickness direction of lens side surface 30. Gate mark 14t of fourth layer 4 having a width smaller than the sum of the width of gate mark 12t of second layer 2 and the width of gate mark 13t of third layer 3 is disposed adjacent to the upper side in the thickness direction of lens side surface 30 of gate mark 12t of second layer 2 and gate mark 13t of third layer 3 disposed side by side. Thus, the gate mark formed by gate mark 11t, gate mark 12t, gate mark 13t, and gate mark 14t has a shape (for example, pyramid shape) corresponding to the shape of lens side surface 30. The sum Tg of the thicknesses of gate mark 11t, gate mark 12t (gate mark 13t) and gate mark 14t is preferably 3 to 10 mm. When the total Tg of the gate thicknesses is less than 3mm, the thickness necessary for the size of two gates for the lens outer surface layer disposed in the widthwise central portion of the lens side surface 30 cannot be secured, and injection and filling into the cavity become difficult. In addition, when the sum Tg of the gate thicknesses exceeds 10mm, a large force is required for gate cutting, and an excessively large gate cutting device is required.

The first layer 1 and the fourth layer 4, which are the outer surface layers of the lens, are molded by a side gate 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 first layer 1 and the fourth layer 4 as the outer surface layers can be molded by faithfully transferring the shapes of the cavity surfaces thereof, and thus a multilayer molded lens 5 having excellent 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.

The second layer 2 and the third layer 3, which are inner surface layers of the lens, have a relatively small cross-sectional area and are molded 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 outer surface layers of the lens at the center as much as possible in the width direction of the lens side surface 30. In the inner surface layer, the cross-sectional area of the gate is relatively small, and transfer failure and unevenness in viscosity of the molten resin, which are caused by slight deviation of the gate position from the widthwise central portion of the lens side surface 30, are melted in the molding of the next layer, and therefore, there is no problem.

As shown in fig. 11, the maximum thickness T4 of the cavity 24 for the fourth layer 4 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 (nth layer) is smaller than the maximum thickness of the third layer (N-1 th layer). With this configuration, it is possible to obtain a multilayer molded lens 5 having excellent optical characteristics by reducing the problem of sink marks and the like due to insufficient cooling of the fourth layer 4 having the shortest cooling time in the molding cycle compared to the other layers.

The maximum thickness T4 of the cavity 24 for the fourth layer 4 is preferably 2 to 4mm, which is as small as possible to make the molten resin easily flowable in the cavity 24.

In a headlamp of a vehicle or the like to which the multilayer molded lens 5 is applied, in order to improve color bleeding in the vicinity of a cutoff line in a predetermined light distribution pattern or to impart a blur effect, it is sometimes required to provide a fine uneven shape on the lens surface. At the time of molding the fourth layer 4, the minute irregularities 20 on the cavity surface 19 are transferred to the molten resin to form minute irregularities on the surface of the lens molded from the fourth layer 4.

As shown in fig. 12 and 13, the minute unevenness 20 is constituted by a myriad of unevenness of about several micrometers to several millimeters formed in a shape similar to a half-wave rectification wave shape or a sine wave shape in a cross section, for example. The minute unevenness 20, which is generally called a texture, is provided on the entire surface or a part of the cavity surface 19 for the fourth layer 4. Further, the minute unevenness 20 is provided on only one cavity surface 19 for the fourth layer 4, and the manufacturing cost needs millions of yen. On the other hand, according to the structure of the mold apparatus in which the minute irregularities are provided on the first layer, it is necessary to provide the minute irregularities on the cavity surface for all the layers including the cooling cavity, and therefore, the cost is 5 times of several millions of yens.

The cooling cavity is formed by cavity face 18c and cavity face 16. The cooling cavity is the same as the cavity formed by cavity surface 18 and cavity surface 16 that forms intermediate molded body 33. Therefore, the cooling cavity can cool the intermediate formed body 33.

The cooling cavity is arranged to be effective for cooling the fourth layer 4 for the shortest cooling time. However, when the fine uneven shape is formed on the fourth layer 4, the finished molded body 34 formed with the fine uneven shape is pressed again by the cooling cavity, and the fine uneven shape is deformed. To avoid this, it is preferable to provide a cooling cavity in the layer immediately preceding the final layer, i.e. the third layer 3. As a result, the third layer 3 is sufficiently cooled, and the layer shape is stabilized without deforming the fine uneven shape, whereby the optical characteristics of the lens are improved.

As described above in detail, 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 lens side surface 30 provided between the pair of lens surfaces 50 on the side of the lens optical axis L, wherein a gate mark group in which N gate marks 11t to 14t, which are traces of side gates in the respective layers from the first layer to the N-th layer, are integrated is formed in the central portion in the width direction of the lens side surface 30.

A multilayer molded lens is molded by injecting molten resin from a side gate into a cavity for molding a first layer and an N-th layer forming a pair of lens surfaces and a cavity for molding from a second layer to an (N & # 8722; 1) th layer forming the inside of the lens, and N gate marks, which are marks of the side gate of each layer from the first layer to the N-th layer, are formed at the center in the width direction of the side surface of the lens. Thus, the multilayer molded lens has an excellent effect of having excellent optical characteristics, because the molten resin having a low pressure loss and no foreign matter is mixed flows uniformly to each corner of the cavity and is filled therein, and the viscosity of the molten resin in the cavity is uniform and the molding is performed. Further, gate cutting is performed in a state where the side gates of the respective layers from the first layer to the nth layer are integrated, and a gate mark group in which N gate marks are integrated is formed. This makes it extremely easy to cut the N side gates from the first layer to the nth layer, thereby achieving an excellent effect of reducing the manufacturing cost.

The present disclosure includes various modifications, adaptations, improvements, and the like that can be implemented based on the knowledge of those skilled in the art. It is needless to say that the embodiments including the above modifications are included in the scope of the present disclosure as long as the embodiments do not depart from the gist of the present disclosure.

For example, although the description has been given of the case where the gates arranged side by side at the widthwise central portion of the lens side surface 30 are gates for the second layer 2 and the third layer 3 (N-1) which are lens inner surface layers, the gates may be configured to include gates for the first layer 1 or the fourth layer 4 (N-1) which are lens outer surface layers.

In addition, the description has been given of the case where two gates are arranged in parallel at the center portion in the width direction of the lens side surface 30, but one or more gates are arranged in parallel at predetermined multiple stages. For example, when the multilayer molded lens includes 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 be arranged side by side.

The shape of the multilayer molded lens is not limited to the above shape, and may be any shape. For example, although the above embodiment shows an example of a plano-convex lens, a biconvex lens in which both the pair of lens surfaces 50 are formed into a curved surface may be used, or a concave lens may be used. Further, the lens side surface 30 is illustrated as a flat surface, but may be a curved surface.

In the multilayer molded lens, a flange portion protruding radially outward in a flange shape is provided around the lens surface 50, and the outer peripheral surface of the flange portion may be in a shape of the lens side surface 30. Fig. 14 is a side view showing a multilayer molded lens 105 according to a modification, and the same members as those of the above embodiment are denoted by the same reference numerals. In the multilayer molded lens 105 having the flange portion 40 in this modification, a gate mark group in which N gate marks (11t to 14t), which are marks of side gates in each of the first to nth layers, are integrated is formed in the center portion in the width direction of the lens side surface 30 forming the outer peripheral surface of the flange portion 40.

The gates 11g, 12g, 13g, and 14g are shown as gates perpendicular to the lens side surface 30, but may not be perpendicular depending on the shape of the lens side surface 30.

The cross-sectional shape of the gate is shown as a square, but a surface not adjacent to another gate may be a curved surface or a trapezoidal surface, for example, instead of a flat surface.

Description of the reference numerals

1 … first layer; 2 … second layer; 3 … a third layer; 4 … fourth layer; 5 … multilayer molded lens (embodiment); 7 … first cavity block; 8 … second cavity block; 11g, 12g, 13g, 14g … gates; 11r, 12r, 13r and 14r … flow passages; 11t, 12t, 13t, 14t … gate mark; 16. 17, 18, 19 … cavity surfaces; 20 … micro concave-convex; 21. 22, 23, 24 … cavities; 25 … land, 30 … lens side; a 50 … lens face; an L … optical axis; maximum thickness of T3 … third layer cavity; t4 … maximum thickness of cavity for fourth layer; sum of Tg … gate thickness; 105 … multilayer molded lens (modified example).

Claims (8)

1. A multilayer molded lens is provided with N layers, wherein N is not less than 3, and the lens is characterized by comprising:

a pair of lens surfaces intersecting the lens optical axis; and

a lens side surface provided between the pair of lens surfaces on a side of the optical axis of the lens,

a gate mark group in which N gate marks, which are traces of side gates of respective layers from the first layer to the N-th layer, are integrated is formed in a widthwise central portion of the lens side surface.

2. The multi-layer molded lens of claim 1,

the gate mark of the first layer has a largest cross-sectional area of the N gate marks.

3. The multilayer molded lens of claim 1 or 2,

the gate marks of a predetermined plurality of layers from the first layer to the nth layer are arranged side by side in the width direction of the lens side surface.

4. The multi-layer molded lens of claim 3,

the gate marks of the predetermined plurality of layers arranged in parallel are gate marks of any one of the second layer to the (N-1) th layer.

5. The multilayer molded lens of any one of claims 1 to 4,

the thickness of the gate mark group is 3-10 mm.

6. The multilayer molded lens of any one of claims 1 to 5,

the maximum thickness of the nth layer is less than the maximum thickness of the (N-1) th layer.

7. The multilayer molded lens of any one of claims 1 to 6,

the maximum thickness of the Nth layer is 2-4 mm.

8. A multilayer molded lens as claimed in any one of claims 1 to 7,

the N-th layer has a fine uneven shape on an outer surface thereof.

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