JP6925083B2 - Molding mold for resin lens plate - Google Patents

Description

The present invention is a molding die for a resin lens plate, and in particular, a molding die for a resin lens plate for forming a resin lens plate having a thin wall shape and having a plurality of lenses molded in high definition by injection molding. Regarding.

As a conventional method for manufacturing the resin lens plate 100, the manufacturing methods shown in FIGS. 8 (A) and 8 (B) are known. FIG. 8A is a top view illustrating a conventional method for manufacturing the resin lens plate 100. FIG. 8B is a side view illustrating a conventional method for manufacturing the resin lens plate 100.

As shown in FIG. 8A, the resin lens plate 100 is formed by compression-injecting a fluidized resin in a high temperature state into a cavity (not shown) of a molding die. The resin lens plate 100 has a lens forming region 102 in which a plurality of lenses 101 are arranged in a matrix, and a lens assembling region 103 formed in an annular shape around the lens forming region 102.

At this time, since the cavity is filled with resin through a resin injection gate (not shown), an injection gate mark 105 is formed on the side surface 104 of the resin lens plate 100. The resin injection gate is within the arrangement region of the lens forming region 102, and is arranged so as to cover the central portion of the cavity.

As shown in FIG. 8B, the resin injection gate is arranged so as to cover the central portion of the cavity even in the thickness direction of the resin lens plate 100, and has a thickness of about 1/3 of that of the resin lens plate 100. It is formed.

Japanese Patent No. 4236418

In the resin lens plate 100, the thickness T3 of the thickest lens forming region is, for example, about 1.5 mm, and the resin injected into the thin cavity becomes difficult to flow in the cavity. Then, as shown in FIGS. 8A and 8B, when the notch property of the injection gate mark 105 is prioritized and the resin injection gate is made thin and small, the corner of the cavity shown by the circle 106 is formed. In the part, there is a problem that an unfilled region is likely to occur.

Further, in the resin injection gate structure, since the resin is filled in advance from the center side of the cavity near the resin injection gate, the resin is filled in both ends of the cavity such as the region indicated by the circle 106. I will be late. Then, in the region near the resin injection gate in the cavity, a large holding pressure at the time of resin filling is applied for a long time until the filling of the resin in the entire cavity is completed.

As a result, the difference in internal stress distribution applied to the resin becomes large between the central portion side and the both end portions side of the cavity, and the resin lens plate 100 may be warped or uneven thickness may occur. In particular, when the warp or the like occurs in the lens forming region 102, there is a problem that the image is disturbed due to birefringence.

Further, FIG. 9A is a top view illustrating the resin lens plate 110 formed by the narrow resin injection gate 111. FIG. 9B is an enlarged explanatory view of the lens forming region of the resin lens plate 110 shown in FIG. 9A.

As shown in FIG. 9A, the resin lens plate 110 has a resin injection gate 111 on the left side of the paper surface, and the resin flows in the cavity (not shown) in the direction indicated by the arrow 114 and is filled. Then, the resin lens plate 110 is formed. The region surrounded by the dotted line is the lens forming region 112, and the lens assembly region 113 is formed around the lens forming region 112.

The resin injection gate 111 is within the arrangement region of the lens forming region 112, and is arranged at the center of the cavity. As described above, depending on the position of the resin injection gate 111, the resin is filled in advance from the central portion side of the cavity as shown by the alternate long and short dash line. As a result, there is a problem that in the region on both ends of the cavity with respect to the filling direction of the resin, the resin wraps around from the center of the cavity and easily becomes a region where the resins merge, and welds are likely to occur.

Further, in the shape in which adjacent lenses 115 of the lens forming region 112 are continuous with each other, there is a problem that the resin easily entrains air in the cavity in the hemispherical recess of the mold surface, and weld is likely to occur. Further, in the continuous region between the individual lenses 115, there is a problem that turbulence is likely to occur on the rear end side in the flow direction of the resin indicated by the arrow 114, and the weld 116 is likely to be generated on the individual lenses 115. be.

FIG. 9B illustrates a situation in which the weld 116 is generated in the lens 115 in the lens forming region 112. The generation of welds 116 on the individual lenses 115 adversely affects the floating image. Then, it is considered that the weld 116 can avoid the occurrence by uniformly flowing the resin in the cavity and filling it, but there is a problem that it is difficult with the current shape of the molding die.

The present invention has been made in view of the above problems, and provides a molding die for a resin lens plate for forming a resin lens plate having a thin wall shape and having a plurality of lenses molded in high definition by injection molding. To do.

The molding mold for the resin lens plate of the present invention includes a first mold and a second mold, and the communication space between the first mold and the second mold is formed with a runner. A molding mold for a resin lens plate having a resin injection gate communicating with the runner and a cavity communicating with the resin injection gate to form a resin lens plate, wherein the cavity is at least the first main body. A lens-forming region in which a plurality of lenses are formed in a matrix on a surface or a second main surface opposite to the first main surface, and a lens assembly region formed in an annular shape around the lens-forming region. It is a space of a substantially hexahedron for molding the resin lens plate having the above, and the resin injection gate has a mold surface of the first mold for forming the first main surface and the second main surface. The resin injection gate and the cavity communicate with the first side surface, which is between the mold surface of the second mold to be molded and is one of the four side surfaces of the substantially hexahedron. In the opening of the resin injection gate in the boundary cross section of the above, the opening width in the thickness direction between the mold surface of the first mold and the mold surface of the second mold of the opening is the above. It extends from the center of the cavity toward both ends of the cavity, and the opening width in the direction perpendicular to the thickness direction of the resin injection gate is the same as the width of the lens forming region or wider than the lens forming region. The runner communicates with the resin injection gate on an extension line of the center of the cavity.

Further, in the molding die of the resin lens plate of the present invention, the communication space communicates with the second side surface of the substantially hexahedron arranged so as to face the first side surface, and is inside the cavity. It has a discard tab for discharging a part of the resin filled in the cavity to the outside of the cavity, and the discard tab is at least a part of the lens forming region with the center of the cavity as the center of the opening region. It is characterized in that it is arranged over.

Further, in the molding die of the resin lens plate of the present invention, at least the mold surface of the first mold or the mold surface of the second mold is formed in the cavity for molding the lens assembly region. A pair of resin flow paths recessed linearly from the resin injection gate side to the discard tab side are provided, and the resin flow path is provided wider than the lens forming region and communicates with the resin injection gate. It is characterized by doing.

Further, in the molding mold for the resin lens plate of the present invention, the lens is molded on at least the mold surface of the first mold or the mold surface of the second mold in the lens forming region. A plurality of hemispherical recesses are formed, and a flat region continuous to the lens assembly region is formed between the recesses.

Further, the molding die for the resin lens plate of the present invention is characterized in that the flat region is roughened and the concave portion is mirrored.

Further, in the molding die of the resin lens plate of the present invention, the opening width in the thickness direction between the mold surface of the first mold and the mold surface of the second mold in the cavity is the above. It is characterized in that it extends from the center of the cavity toward both ends of the cavity.

The molding mold for the resin lens plate of the present invention includes a first mold and a second mold, and the communication space between the first mold and the second mold is a runner and a runner. It has a resin injection gate that communicates with the resin injection gate and a cavity that communicates with the resin injection gate and forms a resin lens plate. The tree resin injection gate communicates with the first side surface, which is one of the four side surfaces of the substantially hexahedral cavity, and is an opening of the resin injection gate in the boundary cross section between the resin injection gate and the cavity. The opening width in the thickness direction of the opening widens from the center of the cavity toward both ends of the cavity, and the opening width in the thickness direction and the direction perpendicular to the thickness direction of the resin injection gate is the same width as the lens forming region or the lens forming region. Wider than. With this structure, the amount of resin injected from the resin injection gate into the cavity is made as uniform as possible, and the difference in internal stress distribution to the resin causes warpage of the resin lens plate and uneven thickness. It is prevented from occurring. Then, the resin lens plate can maintain high quality as an optical product.

Further, in the molding die of the resin lens plate of the present invention, the communication space has a discard tab for discharging a part of the resin filled in the cavity to the outside of the cavity. With this structure, it is possible to easily entrain the air in the cavity by injecting it into the cavity first, and to discharge the resin to which weld is likely to occur to the outside of the cavity due to a temperature drop or the like.

Further, in the molding die of the resin lens plate of the present invention, a pair of resin flow paths recessed linearly from the resin injection gate side to the discard tab side are provided in the cavity region for molding the lens assembly region. ing. Due to this structure, the holding pressure is weaker at both ends of the cavity than at the center side of the cavity, but by increasing the fluidity of the resin, the entire cavity can be filled with the resin as uniformly as possible.

Further, in the molding die of the resin lens plate of the present invention, a plurality of hemispherical recesses for molding a lens are formed on the mold surface of the first mold or the mold surface of the second mold. At the same time, a flat region continuous to the lens assembly region is formed between the recesses. With this structure, when the resin is filled, turbulence is less likely to occur in the resin flow at the rear end of the lens in the resin flow direction, and welds are prevented from occurring in the individual lenses.

Further, in the molding die of the resin lens plate of the present invention, the flat region is roughened and the concave portion is mirrored. With this structure, a light-shielding portion having an aperture diaphragm function is formed in the lens-forming region of the resin lens plate, and a high-quality floating image can be realized.

Further, in the molding die of the resin lens plate of the present invention, the opening width in the thickness direction expands toward both ends of the cavity from the center of the cavity even in the cavity following the resin injection gate, so that the resin is injected. The amount of resin injected from the gate into the cavity can be as uniform as possible.

It is (A) plan view and (B) plan view explaining the molding die of the resin lens plate which concerns on one Embodiment of this invention. It is sectional drawing explaining the molding die of the resin lens plate which concerns on one Embodiment of this invention. It is sectional drawing explaining the molding die of the resin lens plate which concerns on one Embodiment of this invention. It is sectional drawing explaining the molding die of the resin lens plate which concerns on one Embodiment of this invention. It is (A) plan view, (B) plan view, (C) plan view, (D) sectional view explaining the filling state of the resin in the molding die of the resin lens plate which concerns on one Embodiment of this invention. It is (A) perspective view and (B) sectional view explaining the resin lens plate which concerns on other embodiment of this invention. It is (A) sectional view and (B) sectional view explaining the molding die of the resin lens plate which concerns on other embodiment of this invention. It is (A) top view and (B) side view explaining the manufacturing method of the conventional resin lens plate. It is (A) top view and (B) enlarged explanatory view explaining the conventional resin lens plate.

Hereinafter, the molding die 10 of the resin lens plate according to the embodiment of the present invention (hereinafter, referred to as “molding die 10”) will be described in detail with reference to the drawings. In the following description, in principle, the same code number will be used for the same member, and repeated description will be omitted.

FIG. 1A is a plan view illustrating the molding die 10 of the present embodiment. FIG. 1B is a plan view illustrating a mold surface 11A of the first mold 11 of the molding mold 10 of the present embodiment. The mold surface 12A of the second mold 12 in the cavity 13 of the molding mold 10 has the same shape as the mold surface 11A of the first mold 11, and the second mold 12 (see FIG. 2). ), The description of the mold surface 12A (see FIG. 2) refers to the description of the mold surface 11A of the first mold 11, and the description thereof will be omitted.

As shown in FIG. 1A, the molding die 10 is mainly composed of a first die 11 and a second die 12. When the first and second molds 11 and 12 come into contact with each other, the resin 31 (see FIG. 5 (A)) flows in the first and second molds 11 and 12, at the dotted line 21. The indicated communication space 22 is formed. The communication space 22 of the molding die 10 mainly contains a cavity 13 for molding a resin lens plate 41 (see FIG. 6A), a resin injection gate 14 for injecting resin 31 into the cavity 13, and a resin injection gate. A runner 15 communicating with the 14 and a discard tab 16 communicating with the cavity 13 are formed.

The cavity 13 of the molding die 10 is a space of a substantially hexahedron, a resin injection gate 14 is arranged on the side surface of the cavity 13 on the front side of the paper surface, and a discard tab 16 is arranged on the side surface of the cavity 13 on the rear side of the paper surface. It is installed. Then, the resin 31 injected from the resin injection gate 14 fills the inside of the cavity 13 while flowing in the lateral direction (front-back direction of the paper surface) of the cavity 13.

The resin injection gate 14 is arranged over the longitudinal direction (left-right direction of the paper surface) of the side surface of the cavity 13 on the front side of the paper surface. A communication point between the runner 15 and the resin injection gate 14 is arranged on an extension line of the center CL in the longitudinal direction (left-right direction of the paper surface) of the cavity 13.

As shown in FIG. 1 (B), the mold surface 11A of the first mold 11 surrounds the processed surface 11B forming the lens forming region 44 and the processed surface 11B, and forms the lens assembly region 45. And have. Then, on the processed surface 11B, recesses 11D for forming a hemispherical microlens are arranged in a matrix at a predetermined pitch. Although details will be described later, in the present embodiment, a flat region 11E is formed on the machined surface 11B so as to surround the periphery of each recess 11D. In the present embodiment, each minute lens 47 (see FIG. 6B) has a hemispherical shape, but may have an aspherical shape, for example, and in a plan view, for example, a circular shape or a hexagonal shape. It may be in the case of a shape.

Further, in the lens assembly region 45, a pair of resin flow paths 17 (see FIG. 3) are formed wider in the lateral direction (front-back direction of the paper surface) of the cavity 13 than in the lens formation region 44. The resin flow path 17 is a region for improving the flow of the resin 31 in the cavity 13, and a linear recessed region 11F is formed on the processed surface 11C. One end side of the recessed region 11F communicates with the resin injection gate 14. On the other hand, the other end side of the recessed region 11F is located on the discard tab 16 side (rear side of the paper surface) of the processed surface 11B of the lens forming region 44.

FIG. 2 is a cross-sectional view of the molding die 10 shown in FIG. 1A in the AA line direction, and is a diagram for explaining the resin injection gate 14 of the molding die 10.

FIG. 2 shows the shape of the opening 14A of the resin injection gate 14 in the boundary cross section where the resin injection gate 14 communicates with the cavity 13 (see FIG. 1A). As shown in the figure, the opening width W1 of the opening 14A in the lateral direction (vertical direction on the paper surface) is formed so as to be wider at both ends of the cavity 13 than at the center CL of the cavity 13. Specifically, the mold surface 11A of the first mold 11 is formed as a flat surface, and the mold surface 12A of the second mold 12 is formed as an inclined surface with the central CL of the cavity 13 as the apex.

Further, the opening width W2 in the longitudinal direction (left-right direction of the paper surface) of the opening 14A is formed wider than the lens forming region 44. That is, the resin injection gate 14 is formed up to the outside of the lens forming region 44 in the longitudinal direction of the cavity 13 (left-right direction on the paper surface).

Here, as shown in FIG. 1B, the runner 15 communicates with the resin injection gate 14 on the extension line of the central CL of the cavity 13. Then, the resin injection gate 14 communicates with the cavity 13 from the communication point with the runner 15 while gradually expanding the opening cross-sectional area having the shape shown in FIG. With this structure, the central CL of the cavity 13, which is the shortest distance from the runner 15, has a strong holding pressure at the time of resin filling, and the holding pressure gradually weakens toward both ends of the cavity 13. As a result, the resin 31 (see FIG. 5 (A)) is vigorously injected into the cavity 13 toward the center CL of the cavity 13, and is preceded in the cavity 13 in the lateral direction (front-back direction of the paper surface) of the cavity 13. It becomes easy to flow.

However, in the present embodiment, as shown in FIG. 2, the opening width W1 of the opening 14A of the resin injection gate 14 is formed so that both ends of the cavity 13 are wider than the central CL of the cavity 13. .. Due to this structure, the flow cross-sectional area of the resin 31 (see FIG. 5 (A)) increases toward both ends of the cavity 13, and even if the holding pressure during resin filling is slightly weakened, the fluidity of the resin 31 increases. It is possible to supply the resin 31 to both ends of the cavity 13 as uniformly as possible with the central CL side.

Further, the resin injection gate 14 is formed up to the outside of the lens forming region 44 in the longitudinal direction of the cavity 13 (left-right direction on the paper surface). Due to this structure, when the cavity 13 is filled with resin, in the lens forming region 44, merging due to the resin 31 wrapping around from the center CL side of the cavity 13 is less likely to occur, and the resin lens plate 41 (see FIG. 6A). Weld lines are prevented from being formed in the lens forming region 44 of the above.

FIG. 3 is a cross-sectional view of the molding die 10 shown in FIG. 1A in the BB line direction, and is a diagram for explaining the resin flow path 17 of the molding die 10.

As shown in FIG. 3, the resin flow path 17 is formed in the lens assembly region 45 of the first and second molds 11 and 12. Then, the recessed regions 11F and 12F formed on the processed surfaces 11C and 12C of the first and second dies 11 and 12 coincide with each other. The space width W3 in the thickness direction (paper surface vertical direction) of the resin flow path 17 is, for example, 0.9 mm or more and 1.5 mm or less, which is equal to or wider than the space width W4 of the flat regions 11E and 12E of the lens forming region 44. , It is slightly narrower than the space width W5 of the recesses 11D and 12D for lens molding.

As described above with reference to FIG. 1 (B), the resin flow path 17 of the cavity 13 has a runner 15 (see FIG. 1 (B)) and a resin injection gate 14 (see FIG. 1 (B)) in the cavity 13. It is located at the position farthest from the communication point, and the holding pressure at the time of resin filling is weaker than the central CL of the cavity 13. However, since the linear resin flow path 17 is formed in the lateral direction (front-back direction of the paper surface) of the cavity 13, the filling speed in the lens assembly region 45 can be increased.

FIG. 4 is a cross-sectional view of the molding die 10 shown in FIG. 1A in the CC line direction, and is a diagram for explaining a discard tab 16 of the molding die 10.

First, as shown in FIG. 1A, the discard tab 16 is arranged on the side surface of the cavity 13 on the opposite side to the side surface of the cavity 13 in which the resin injection gate 14 is arranged. Then, in the boundary cross section with the cavity 13 through which the discard tab 16 communicates, the center of the opening region of the discard tab 16 coincides with the center CL of the cavity 13, and the discard tab 16 covers at least a part of the lens forming region 44. It is arranged so as to do so.

Next, as shown in FIG. 4, in the discard tab 16, for example, the mold surface 11A of the first mold 11 is formed as a flat surface continuous with the cavity 13, and the mold surface 12A of the second mold 12 is uneven. It is formed in a shape. Then, a part of the resin 31 (see FIG. 5 (A)) flowing through the lens forming region 44 of the cavity 13 flows into the discard tab 16, and the lens forming region 44 of the resin lens plate 41 (see FIG. 6 (A)) flows into the discard tab 16. Welds and the like that may occur in the cavity 13 can be discharged to the outside of the cavity 13. As a result, in particular, it is possible to prevent the lens forming region 44 of the resin lens plate 41 from being welded or warped, and to maintain the high quality of the resin lens plate 41 as an optical product.

5 (A) to 5 (C) are plan views for explaining the filling state of the resin 31 in the molding die 10 of the present embodiment, and FIG. 5 (D) is the molding die of the present embodiment. It is sectional drawing explaining the filling state of the resin 31 in a mold 10. In FIGS. 5 (A) to 5 (C), the molding die 10 is shown in a simplified manner for convenience of explanation.

At the time of resin filling, the liquid or semi-solid resin 31 melted in the pod (not shown) is injected into the cavity 13 from the resin injection gate 14 via the runner 15. Here, in the present embodiment, as the resin 31, a cycloolefin polymer resin, a polycarbonate resin, or an acrylic resin is used.

As the resin molding conditions, for example, the resin 31 is heated by the pod so that the temperature in the cavity 13 is 270 ° C. or higher and 290 ° C. or lower, and the injection speed into the cavity 13 is 20 mm / s or more and 50 mm / s or less, the holding pressure is adjusted to be 50 Mpa or more and 80 Mpa or less.

As shown in FIG. 5A, the resin 31 adjusted to the above resin molding conditions is injected into the cavity 13 from the resin injection gate 14. Then, as described with reference to FIGS. 1 and 2, the runner 15 communicates with the resin injection gate 14 at the center CL of the cavity 13. Further, the opening 14A of the resin injection gate 14 is formed so that the opening width W1 is wider at both ends of the cavity 13 than at the center CL of the cavity 13.

With this structure, the amount of the resin 31 injected from the resin injection gate 14 into the cavity 13 is slightly smaller than that on the central CL side of the cavity 13 even on both ends of the cavity 13. By providing a pair of resin flow paths 17 at both ends of the cavity 13, the fluidity of the resin 31 is also improved. As a result, the resin 31 injected into the central CL side of the cavity 13 flows slightly ahead of the other due to the holding pressure, but as shown in the figure, the resin 31 is discarded in the entire cavity 13. Flow as evenly as possible toward the tab 16 side.

Next, as shown in FIG. 5B, by continuously injecting the resin 31 into the cavity 13 from the resin injection gate 14, the inside of the cavity 13 is filled with the resin 31. As described above with reference to FIG. 3, resin flow paths 17 communicating with the resin injection gate 14 having a wide opening width W1 are arranged on both ends of the cavity 13.

With this structure, the injection amount of the resin 31 on both ends of the cavity 13 is increased, and the fluidity of the resin 31 is further improved. Then, the resin 31 flows as uniformly as possible toward the discard tab 16 side in the entire cavity 13. As a result, at least in the lens forming region 44, the resin 31 that flows in one direction (the front-back direction of the paper surface) is filled, so that merging due to the resin 31 wrapping around in the cavity 13 is less likely to occur, and the resin lens plate. Weld lines are prevented from being formed in the lens forming region 44 of 41 (see FIG. 6A).

Next, as shown in FIG. 5C, by continuously injecting the resin 31 into the cavity 13 from the resin injection gate 14, the inside of the cavity 13 is completely filled with the resin 31, and the cavity is first filled. A part of the resin 31 injected into 13 flows into the discard tab 16. Here, the resin 31 first injected into the cavity 13 flows while entraining the air in the cavity 13, and the temperature tends to decrease, so that welds are likely to occur.

Then, by providing the discard tab 16, the resin 31 in the region where welds are likely to occur can be poured out to the outside of the cavity 13. Alternatively, the resin 31 in the region where welds are likely to occur can be driven into the lens assembly region 45. As a result, in particular, the occurrence of welds, warpage, etc. in the lens forming region 44 of the resin lens plate 41 is prevented, and the resin lens plate 41 (see FIG. 6A) maintains high quality as an optical product. Can be done.

Further, as described with reference to FIGS. 5 (A) to 5 (C), the resin 31 flows through the entire cavity 13 as uniformly as possible to form a lens located on the center CL side of the cavity 13. It is possible to prevent the region 44 from being filled first and then the regions on both ends of the cavity 13 being filled with a significant delay. This structure prevents a large holding pressure during resin filling from being applied for a long time to the region of the center CL of the cavity 13 near the resin injection gate 14. As a result, the difference in internal stress distribution to the resin 31 prevents the resin lens plate 41 from being warped and uneven thickness. The resin lens plate 41 can maintain high quality as an optical product.

Finally, as shown in FIG. 5 (D), in the lens forming region 44, the resin 31 flows through the thick portion of the resin lens plate 41 (see FIG. 6 (A)) as shown by the arrow 33. , The recesses 11D and 12D provided in the first and second molds 11 and 12 are also filled. As shown in the figure, flat regions 11E and 12E are formed in the first and second molds 11 and 12 so as to surround the recesses 11D and 12D, and the flat regions 11E and 12E are formed in the lens forming region 44. It is continuous in a mesh pattern, and its end portion is continuous to the lens assembly region 45 (see FIG. 1 (B)).

Here, the radius of curvature of the recesses 11D and 12D is formed, for example, at a pitch of 0.4 mm or more and 0.6 mm or less, and the recesses 11D and 12D are formed in a matrix at a pitch of 0.3 mm or more and 0.5 mm or less. ing. With this structure, as shown by the circle 34, in the flow direction of the resin 31 (in the front-rear direction of the paper surface), the protrusion shape of the boundary region between the recesses 11D and 12D and the flat regions 11E and 12E is eliminated, and the recesses 11D and 12D are eliminated. The depth of is shallow. As a result, turbulence is less likely to occur in the boundary region between the recesses 11D and 12D and the flat regions 11E and 12E, and the lens 47 (see FIG. 6 (A)) of the resin lens plate 41 shown by the circle 34 (see FIG. 6A). Weld 116 (see FIG. 9B) is less likely to occur on the rear end side (see FIG. 6B), and birefringence prevents adverse effects on the floating image.

Next, the resin lens plate 41 according to another embodiment of the present invention will be described in detail with reference to the drawings. Since the resin lens plate 41 is molded by using the molding die 10 described above with reference to FIGS. 1 to 5, the resin lens plate 41 will be described with reference to FIGS. 1 to 5 below. The description of the molding die 10 described above will be referred to as appropriate, and in principle, the same code number will be used for the same member, and the repeated description will be omitted.

FIG. 6A is a perspective view illustrating the resin lens plate 41 of the present embodiment. FIG. 6B is an enlarged cross-sectional view illustrating the resin lens plate 41 of the present embodiment.

FIG. 6A shows the resin lens plate 41 immediately after being released from the molding die 10. The resin lens plate 41 is a thin plate-shaped substantially hexahedron. Most of the first main surface 42 (see FIG. 6B) and the second main surface 43 of the resin lens plate 41 are formed as the lens forming region 44 and surrounds the periphery of the lens forming region 44. As described above, the lens assembly region 45 is formed in an annular shape. The lens assembly region 45 forms the outer peripheral end portion 46 of the resin lens plate 41.

As described above, the shape of the mold surface 11A (see FIG. 1 (B)) of the first mold 11 (see FIG. 1 (B)) is transferred to the first main surface 42, and the second main surface 42 is transferred. The shape of the mold surface 12A (see FIG. 2) of the second mold 12 (see FIG. 2) is transferred to the surface 43. A plurality of spherical lenses 47 are formed in a matrix on the first and second main surfaces 42 and 43.

As shown in the figure, immediately after the mold is released from the molding die 10, the resin lens plate 41 has a cured resin 48 and a runner 15 (FIG. 1) cured in the shape of the resin injection gate 14 (see FIG. 1 (A)). The cured resin 49 cured in the shape of (see (A)) and the cured resin 50 cured in the shape of the discard tab 16 (see FIG. 1 (A)) are integrally formed.

In FIG. 6B, a part of the lens forming region 44 is enlarged and shown. As described above, in the lens forming region 44 of the resin lens plate 41, a plurality of lenses 47 are formed in a matrix at a pitch of, for example, 0.3 mm or more and 0.5 mm or less. The space between the lenses 47 is formed as a flat region 51. Then, as shown by the alternate long and short dash line 52, a plurality of the first and second main surfaces 42 and 43 of the resin lens plate 41 are aligned so that the optical axes of the lenses 47 in the thickness direction (vertical direction of the paper surface) coincide with each other. Lens 47 is formed.

In the lens forming region 44, the thickness T1 of the forming region of the lens 47 is formed to be, for example, 1.2 mm ± 0.5 mm, and the thickness T2 of the forming region of the flat region 51 is formed to be, for example, 1.1 mm ± 0.5 mm. Is formed by. The radius of curvature of the lens 47 is formed to be, for example, 0.4 mm or more and 0.6 mm or less.

As shown in the figure, the flat region 51 is roughened as shown by a thick line, while the lens 47 is mirrored. Specifically, the regions corresponding to the flat regions 11E and 12E of the mold surfaces 11A and 12A of the first and second molds 11 and 12 are roughened by blasting, chemical etching and polishing. Is given.

Then, the two resin lens plates 41 are bonded together using the lens assembly region 45 in a state where the optical axes of the plurality of lenses 47 are aligned with each other, whereby a resin upright lens array (not shown). ). As described above, the flat region 51 that has been roughened is formed in the lens forming region 44, so that the transmitted light that has entered the resin lens plate 41 from other than the lens 47 region is transmitted in the flat region 51. It can be diffusely reflected. That is, the flat region 51 is used as a light-shielding portion as an aperture diaphragm function, so that a high-quality floating image can be realized.

Next, the molding die 60 according to another embodiment of the present invention will be described in detail with reference to the drawings. The molding die 60 has substantially the same structure as the molding die 10 described with reference to FIGS. 1 to 4 except that the shape of the cavity 62 is different. , The description of the molding die 10 and the resin lens plate 41 described with reference to FIGS. 1 to 6 will be appropriately referred to, and in principle, the same code number will be used for the same member, and the repeated description will be omitted.

FIG. 7A is a cross-sectional view illustrating the molding die 60 of the present embodiment, and shows a cross section of the molding die 10 shown in FIG. 1A in the DD line direction. FIG. 7B is an enlarged cross-sectional view illustrating the region indicated by the circle 63 of the molding die 60 of FIG. 7A.

As shown in FIG. 7A, the molding die 60 is mainly composed of the first mold 11 and the second mold 12, similarly to the molding die 10. When the first and second molds 11 and 12 come into contact with each other, the resin 31 (see FIG. 5 (A)) flows in the first and second molds 11 and 12, and the dotted line 21 (FIG. 5). The communication space 22 (see FIG. 1 (A)) shown in 1 (A)) is formed. The communication space 22 of the molding die 60 mainly has a cavity 62 for molding the resin lens plate 41 (see FIG. 6 (A)) and a resin injection gate 14 for injecting the resin 31 into the cavity 62 (FIG. 1 (A)). ), A runner 15 communicating with the resin injection gate 14 (see FIG. 1A), and a discard tab 16 communicating with the cavity 62 (see FIG. 1A).

As shown in the figure, recesses 11D for forming a hemispherical microlens are arranged in a matrix at a predetermined pitch on the mold surface 11A of the first mold 11 and the mold surface 12A of the second mold 12. ing. The two-dot chain lines 64 and 65 indicate the inclined lines of the mold surface 12A of the second mold 12, and the mold surface 12A of the second mold 12 has the same structure as the resin injection gate 14 described above. , Both ends of the cavity 62 are formed to be wider than the central CL of the cavity 62. Specifically, the mold surface 12A of the second mold 12 is formed as an inclined surface with the central CL of the cavity 62 as the top. The present embodiment is not limited to the case where the mold surface 12A of the second mold 12 is formed as an inclined surface. For example, when the mold surface 11A of the first mold 11 is an inclined surface and the mold surface 12A of the second mold 12 is a flat surface (horizontal plane), or when the mold surface 11A and the second mold surface 11A of the first mold 11 are used. The mold surface 12A of the mold 12 may be an inclined surface.

In FIG. 7B, for convenience of explanation, the inclination of the mold surface 12A of the second mold 12 is shown to be larger than the actual inclination, but in the second mold 12, the center CL of the cavity 62 is shown. The depth of the recess 11D is deeper on the side than on the end side of the cavity 62. On the contrary, the space width W4 of the flat regions 11E and 12E between the recesses 11D of the cavity 62 is shorter on the center CL side of the cavity 62 than on the end side of the cavity 62. The mold surface 11A of the first mold 11 is formed as a flat surface.

Due to this structure, the flow cross-sectional area of the resin 31 (see FIG. 5 (A)) increases toward both ends of the cavity 62, and even if the holding pressure during resin filling is slightly weakened, the fluidity of the resin 31 increases. It is possible to supply the resin 31 to both ends of the cavity 62 as uniformly as possible with the central CL side.

Further, by inclining the inside of the cavity 62 continuously with the resin injection gate 14, when the cavity 62 is filled with resin, in the lens forming region 44 (see FIG. 2), the area around the resin 31 from the center CL side of the cavity 62. Convergence due to crowding is less likely to occur, and weld lines are prevented from being formed in the lens forming region 44 of the resin lens plate 41 (see FIG. 6A).

In this embodiment, since the plurality of lenses 47 are formed on the first and second main surfaces 42 and 43 of the resin lens plate 41, the mold surfaces 11A and 12A of the first and second molds 11 and 12 are formed. However, the case where a plurality of recesses 11D and 12D for forming a lens are formed has been described, but the present invention is not limited to this case. For example, in order to form a plurality of lenses 47 on at least one of the first main surface 42 and the second main surface 43 of the resin lens plate 41, the mold surfaces 11A of the first and second molds 11 and 12 are formed. The same effect can be obtained even when a plurality of lens forming recesses 11D and 12D are formed in either one of 12A and 12A.

Further, the case where the opening width W2 in the longitudinal direction (left-right direction of the paper surface) of the opening 14A of the resin injection gate 14 shown in FIG. 2 is formed wider than the lens forming region 44 has been described, but is limited to this case. It's not a thing. For example, the opening width W2 of the opening 14A may be the same width as or slightly narrower than the lens forming region 44. That is, in the lens forming region 44, the resin 31 on the center CL side of the cavity 13 wraps around to prevent the generation of weld lines, and the resin 31 is filled with the resin 31 as uniformly as possible in the entire cavity 13. It suffices if the occurrence of internal stress distribution difference is prevented. In addition, various modifications can be made without departing from the gist of the present invention.

10, 60 Resin lens plate molding mold 11 First mold 11A, 12A Mold surface 11B, 11C, 12C Processed surface 11D, 12D Recessed portion 11E, 12E Flat area 11F, 12F Recessed region 12 Second mold 13, 62 Cavity 14 Resin injection gate 14A Opening 15 Runner 16 Discard tab 17 Resin flow path 31 Resin 41 Resin lens plate 42 First main surface 43 Second main surface 44 Lens forming area 45 Lens assembly area 47 Lens 48, 49, 50 Hardened resin 51 Flat area

Claims (6)

A first mold and a second mold are provided, and the communication space between the first mold and the second mold includes a runner, a resin injection gate communicating with the runner, and the said. A molding die for a resin lens plate having a cavity for molding a resin lens plate, which communicates with a resin injection gate.
The cavity has a lens forming region in which a plurality of lenses are formed in a matrix on at least a first main surface or a second main surface opposite to the first main surface, and an annular shape around the lens forming region. a lens assembly region formed a between empty you molding the resin lens plate having,
The resin injection gate is between the mold surface of the first mold for molding the first main surface and the mold surface of the second mold for molding the second main surface. Communicating with the first side surface, which is the boundary cross section between the resin injection gate and the cavity,
At the opening of the resin injection gate on the first side surface,
The opening width in the thickness direction between the mold surface of the first mold and the mold surface of the second mold of the opening widens from the center of the cavity toward both ends of the cavity.
The opening width in the direction perpendicular to the thickness direction of the resin injection gate is the same as the width of the lens forming region or wider than the lens forming region.
A molding die for a resin lens plate, wherein the runner communicates with the resin injection gate on an extension line of the center of the cavity. The communication space is between the first mold die surface and the second mold die surface of, with respect to the first side and opposite to arranged to Ru second side It has a waste tab for communicating and discharging a part of the resin filled in the cavity to the outside of the cavity.
The molding die for a resin lens plate according to claim 1, wherein the discard tab is arranged with the center of the cavity as the center of the opening region over at least a part of the lens forming region. In the cavity for forming the lens assembly region,
At least on the mold surface of the first mold or the mold surface of the second mold , a pair of resin flow paths recessed linearly from the resin injection gate side toward the discard tab side are provided.
The molding die for a resin lens plate according to claim 2, wherein the resin flow path is provided wider than the lens forming region and communicates with the resin injection gate. At least the mold surface of the mold surface of the first mold or the second mold of the lens forming region, the recess of the plurality of hemispherical shape for molding the lens is formed, each of said recesses The molding die for a resin lens plate according to any one of claims 1 to 3, wherein a flat region continuous to the lens assembly region is formed between the molding dies. The molding die for a resin lens plate according to claim 4, wherein the flat region is rough-faced and the concave portion is mirror-finished. The opening width in the thickness direction between the mold surface of the first mold and the mold surface of the second mold in the cavity extends from the center of the cavity toward both ends of the cavity. The molding die for a resin lens plate according to any one of claims 1 to 5, characterized in that.

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