JP6439604B2 - Optical element and optical element manufacturing method - Google Patents

Description

  The present invention relates to an optical element molded using a mold and a method for manufacturing the optical element.

  In recent years, in mobile terminals such as smartphones, in order to improve the design, the downsizing of the image pickup device mounted thereon has been promoted, and accordingly, the demand for a low-profile optical system mounted in the image pickup device has been increasing. Yes. On the other hand, higher performance of the optical system is also required so that high-quality images can be taken even for portable terminals.

  In response to these requirements, a plurality of object images are imaged by a solid-state image sensor using a lens array (array optical system) composed of a plurality of imaging optical systems (single-eye optical systems) arranged with different optical axes. A small and thin imaging device using so-called super-resolution technology that reconstructs one image by individually forming in the image area on the surface and processing the image signal corresponding to each object image has been developed. It came to be. In an imaging optical system used in such an imaging apparatus, a high-pixel image can be created from a low-pixel image by reconstructing a plurality of images, and thus each single-eye optical system forms an individual-eye image. The number of pixels in the area can be reduced. As a result, it is possible to provide a high-resolution imaging device while realizing a significantly lower profile than existing optical systems.

  By the way, if the single-eye optical system is formed from individual lenses, it takes time to assemble, and therefore it is preferable to use a lens array in which a plurality of lenses are arranged in parallel. In addition, when such a lens array is formed of plastic, a lens array in which an intended shape is reflected with high accuracy can be manufactured at a low cost. However, one problem in using such a lens array is that unnecessary reflected light or the like is generated as in the case of a monocular lens, or the light emitted from the lens is incident on the adjacent image area, and the subject. There is a possibility that a ghost that adversely affects the image may appear. In order to suppress such unnecessary light, it is effective to provide a diaphragm member having a plurality of openings facing each lens. Since the diaphragm member also has a function of determining the F number of the optical element, it is generally used for a monocular lens. Therefore, it is conceivable to divert a metal diaphragm provided in a monocular lens or the like and bond a metal diaphragm having a plurality of openings to the lens array. If the position is shifted, the optical performance may be deteriorated. Therefore, a device for accurately positioning the plurality of lenses and the opening is required.

  As a technique for joining a metal diaphragm plate to a lens array, a technique has already been developed in which a diaphragm plate is installed in a positioning portion provided in the lens array, and further a black adhesive is applied and bonded and fixed. However, it takes a relatively long time for the adhesive to cure, and in addition, as described above, highly accurate positioning adjustment of the lens array and the diaphragm plate is also required before bonding. Tools are also required, increasing the number of manufacturing steps. Further, when the adhesive is applied, the outer peripheral portion of the diaphragm plate is not sufficient, and it is necessary to apply the adhesive to the central portion of the lens array in order to prevent the flange portion from being raised and lowered near the center. Further, if the diaphragm plate floats in the vicinity of the optical surface, unnecessary light is likely to leak. Therefore, it is necessary to fill the gap between the diaphragm plate and the lens array by applying a black adhesive to the boundary of the optical surface. However, if the amount of the adhesive applied to the vicinity of the optical surface including the central portion of the lens array is too large, the applied adhesive protrudes and contaminates the optical surface when the diaphragm plate is brought into close contact with the lens array. This phenomenon is likely to occur, the degree of difficulty in applying the adhesive is high, and the assembly yield deteriorates.

  On the other hand, another approach for suppressing unnecessary light in the lens array has been studied. For example, a technique for integrating a film with a molded product by insert molding has been known for a long time. Therefore, there is an attempt to simplify the assembly process and promote cost reduction by insert molding a film in which an opening is formed in the lens array using such a technique. For example, Patent Document 1 describes that an insert molded product is used for a switch panel of an OA device or the like, and a plurality of positioning holes are provided in the outer peripheral portion of the insert film, and a pin is inserted into the hole. Thus, a technique for positioning a film in a mold and joining the film at the time of molding a molded product is disclosed. However, the technique disclosed in Patent Document 1 only discloses a technique for joining a flat and uniform film having no opening for the lens portion of the lens array and a flat molded product. Patent Document 2 discloses a technique for bonding a polarizing sheet film having homogeneous optical characteristics to the entire surface of a lens for spectacles, which is a molded product, and the mold is formed by a suction hole provided on the outer periphery of the sheet. A technique for sucking on the molding surface is disclosed.

Japanese Patent No. 3488760 Japanese Patent No. 3607493

  In particular, in a lens array having a plurality of optical surfaces, high-precision positioning between the optical surface and the aperture is required not only in the direction orthogonal to the optical axis but also in the rotation direction, unlike the positioning of the monocular optical element and the diaphragm plate There is a specificity to become. In addition, when molding a general lens array, in order to obtain a highly accurate optical surface shape, a predetermined pressure (for example, 60 MPa or more) is applied to the resin to compensate for the heat shrinkage of the resin in the mold cavity. Often pushed into the mold. Therefore, even if the film can be placed at an appropriate position in the mold, the film may be displaced by the pressure of the inflowing resin.

  The present invention has been made in view of such problems, and an optical element capable of positioning the opening of the film and the optical surface of the lens array with high accuracy while reducing the cost by a simple process, and An object of the present invention is to provide a method for manufacturing an optical element.

The optical element of the present invention is an optical element formed by joining a film formed from a non- light- transmitting resin material and a lens array having a plurality of optical surfaces transferred and formed by molding using a mold. ,
In the film, a circular hole, a long hole or notch whose longitudinal direction is the direction toward the circular hole, and a plurality of openings are formed,
The mold includes a plurality of mold side optical surfaces that transfer and form the optical surface, a mounting surface on which the film is mounted, and a first convex portion that is disposed in a central region of the mounting surface. A second convex portion disposed in a peripheral region closer to the outer periphery than the central region on the placement surface is formed,
In a state where each opening is positioned with respect to the mold side optical surface so that the first convex portion is inserted into the circular hole and the second convex portion is inserted into the elongated hole or notch. , after the film is attached to the mounting surface of the mold, by flowing melted resin into the mold, thereby molding the lens array by solidifying, Ri name by joining the film ,
A first concave portion formed by transferring the first convex portion is formed in the circular hole, and the second convex portion is transferred after the resin is filled to the edge of the elongated hole or notch. A second recess is formed .

The optical element manufacturing method of the present invention includes an optical element formed by joining a film formed from a non-light-transmitting resin material and a lens array having a plurality of optical surfaces transferred and formed by molding using a mold. A manufacturing method of
The mold includes a plurality of mold side optical surfaces that transfer and form the optical surface, a mounting surface on which the film is mounted, and a first convex portion that is disposed in a central region of the mounting surface. The second convex portion disposed in the peripheral region closer to the outer periphery than the central region on the placement surface, and a suction hole are formed,
The first convex portion is formed into the circular hole while bringing the film having a circular hole, a long hole or notch whose longitudinal direction is the direction toward the circular hole, and a plurality of openings to the mold. The film is inserted so as to cover the suction hole in a state where each opening is positioned with respect to the mold side optical surface so that the second convex portion is inserted through the elongated hole or notch. Is mounted on the mold,
Sucking and holding the film through the suction holes;
Clamp the mold,
Pour molten resin into the mold,
While shaping the lens array by solidifying the resin, the film is joined,
A first concave portion is formed by transferring the first convex portion into the circular hole, and the second convex portion is transferred after filling the resin into the edge of the elongated hole or notch. To form a second recess,
The optical element is released from the mold.

  According to the present invention, it is possible to provide an optical element and an optical element manufacturing method capable of positioning the opening of the film and the optical surface of the lens array with high accuracy while reducing the cost by a simple process. it can.

It is a figure which shows typically the imaging device concerning this Embodiment. It is an expanded sectional view of lens unit LU. It is sectional drawing of lens unit LU. It is sectional drawing of the metal mold | die unit which shape | molds 1st lens array LA1. It is the figure which cut | disconnected the metal mold unit of FIG. 4 by the VV line, and looked at the arrow direction. It is a cross-sectional perspective view of the fixed mold unit FM. It is an expansion perspective view of a convex part. It is a figure which shows the range of a center area | region and a periphery area | region. It is a figure explaining the process of insert-molding 1st light shielding film SH1 and 1st lens array LA1. It is a front view of 1st light shielding film SH1. It is a figure which shows the state which mounted | wore 1st light shielding film SH1 on the film mounting surface FL of 2nd metal mold | die MD2. It is a figure which expands and shows the site | part shown by arrow XII in FIG.9 (d). It is a front view which shows 1st light shielding film SH1 concerning each modification. It is an end view of 2nd metal mold | die MD2 concerning a modification.

  Hereinafter, a lens unit using an optical element according to an embodiment of the present invention, an imaging device using the lens unit, and the like will be described. In the lens unit, a plurality of single-lens portions (with a common optical axis) are arranged in a matrix for one image pickup device, and each single-lens portion is picked up with substantially the same field of view. It is usually divided into a super-resolution type and a field division type in which each individual lens unit captures a different field of view. Either type can be realized, but in this embodiment, a super-resolution lens unit that combines a plurality of low-resolution images of the same subject by image processing and outputs a single high-resolution image. explain.

  FIG. 1 schematically shows an imaging apparatus according to the present embodiment. As shown in FIG. 1, the imaging apparatus CA includes an imaging unit CU, a digital processing circuit DP including an image processing circuit IP, a recording unit RD that can store image data via an interface IF, and an image that displays an image based on the image data. It has a display unit DSP and a control unit CPU for controlling them. The control unit CPU receives an operation signal from the operation key KY and controls the circuit.

  The imaging unit CU includes one imaging element SR mounted on the circuit board ST, a lens unit LU that performs a plurality of images on the imaging element SR, and an A / D conversion unit AD. As the image sensor SR, for example, a solid-state image sensor such as a CCD image sensor or a CMOS image sensor having a plurality of pixels is used. A lens unit LU is provided on the light receiving surface SS, which is a photoelectric conversion unit of the image sensor SR, so that optical images of a plurality of subjects are formed.

  An operation of the imaging apparatus CA will be described. The plurality of subject images formed by the lens unit LU are respectively formed in a plurality of image areas whose coordinates are determined in advance on the light receiving surface SS of the imaging element SR. According to the present embodiment, the first light-shielding film SH1, the second light-shielding film SH2, and the third light-shielding member SH3, which will be described later, are provided, so that the subject light passing through each single-eye optical system enters the adjacent image area. Or generation of unnecessary reflected light can be effectively suppressed. Under the control of the control unit CPU, it is individually converted into a plurality of analog signals in the image area where the subject image is formed, further converted into a digital signal by the A / D conversion unit AD, and input to the digital processing circuit DP. The This digital signal is synthesized by the image processing circuit IP to form image data corresponding to one synthesized image. Such image data is input to the image display unit DSP to display a composite image, or is input to the recording unit RD via the interface IF and stored.

  FIG. 2 is a cross-sectional view of the lens unit LU held by the lens frame HLD. FIG. 3 is an exploded perspective view of the lens unit LU. As shown in FIG. 3, the lens unit LU has a quadrangular shape when viewed from the optical axis direction, and in order from the object side, the first lens array LA1 joined with the first light shielding film SH1 and the second lens joined with the second light shielding film SH2. A two-lens array LA2 and a third light shielding member SH3 are disposed, and these are bonded to each other and held by a lens frame HLD. As shown in FIG. 2, the lens frame HLD includes a peripheral wall HLLa and a ceiling wall HLDb connected to the object side. The first light-shielding film SH1 made of resin forms a plurality of (in this case, 16 pieces arranged in 4 rows and 4 columns) openings AP1 corresponding to the plurality of lens portions L1 and L2 of the first and second lens arrays. As described later, the first lens array LA1 is bonded to the object side surface. The first light shielding film SH1 functions as an aperture stop.

  The first lens array LA1 is formed by integrating a plurality of (here, 16 elements arranged in 4 rows and 4 columns) first lens portions L1 and a flange portion L1f that connects the first lens portions L1. Forming. The second lens array LA2 includes a plurality of (here, 16 pieces arranged in 4 rows and 4 columns) second lens portions L2 and second lenses L2 corresponding to the first lens portions L1 of the first lens array LA1. A flange portion L2f that connects the two is integrally formed. The first lens array LA1 and the second lens array LA2 are injection molded using plastics such as polycarbonate and acrylic resin, respectively, and are configured as an integral body made of plastic.

  The resin-made second light-shielding film SH2 has a plurality of openings AP2 (here, 16 pieces arranged in 4 rows and 4 columns) corresponding to each of the second lens portions L2, and the second lens. It is joined to the object side surface of the array LA2. The third rectangular light-shielding member SH3 made of metal, such as SUS, forms a plurality (16 in this example, four rows and four columns) of openings AP3 corresponding to the lens portions L1 and L2. It is bonded to the image side surface of the second lens array LA2 by the adhesive BD shown in FIG. The centers of the apertures AP1, AP2, AP3 and the optical axes of the first lens unit L1 and the second lens unit L2 coincide with each other, and a single-eye optical system is configured by these. The light shielding films SH1 and SH2 prevent unwanted light from entering the adjacent single-eye optical system, and the third light shielding member SH3 allows unnecessary light to enter the imaging region of the solid-state imaging device corresponding to the adjacent single-eye optical system. To prevent it.

  In FIG. 2, an IR cut filter F, which is a translucent parallel plate, is disposed between the second lens array LA2 and the image pickup element SR, and its peripheral edge is in contact with the peripheral wall HLLa of the lens frame HLD. It is glued. A fourth light shielding film SH4 having an opening AP4 in 4 rows and 4 columns is adhered to the object-side surface of the IR cut filter F.

  FIG. 4 is a cross-sectional view of a mold unit for molding the first lens array LA1. A base mold (not shown) is provided around the mold unit shown in FIG. FIG. 5 is a view of the mold unit of FIG. 4 taken along the line V-V and viewed in the direction of the arrow, but is partially omitted. FIG. 6 is a cross-sectional perspective view of the fixed mold unit FM. In FIG. 4, a first mold (also referred to as a first core) MD1 is attached to an end of a movable mold unit MM that can be moved in the axial direction by a drive source (not shown). The first mold MD1 has four pin holes MD1a, and the protrusion pins PR inserted into the pin holes MD1a are provided so as to be protruded by the protrusion mechanism DR provided in the movable mold unit MM. Yes. The first mold MD1 has a mold side optical surface arranged in 4 rows and 4 columns and a flange surface transfer surface.

  As shown in FIG. 6, the fixed mold unit FM arranged opposite to the movable mold unit MM and fixed to the base mold (not shown) is attached with the back plate BS, the base AT, and the cavity member FR in this order. It has been. An adjustment plate HD and a second mold (also referred to as a second core) MD2 are held in the cavity member FR. Note that FH is a hole through which a bolt (not shown) for fixing the back plate BS, the pedestal AT, and the cavity member FR to each other is inserted.

  The adjustment plate HD and the second mold MD2 are fixed to the base AT by screwing the main bolt BT into the central screw hole MD1a. Corresponding to the head of the main bolt BT, a recess CB formed in the back plate BS is connected to an external negative pressure source through a passage (not shown). The adjustment plate HD is provided with four through holes PH (only two are shown in FIG. 6). One end (the lower end in FIG. 6) of the through hole PH communicates with the recess CB through a gap between the pedestal AT and the adjustment plate HD and a radial gap between the side surface of the main bolt BT and the hole inserted. Yes. On the other hand, the other end (upper end in FIG. 6) of the through hole PH communicates with four circular openings CO provided near the corners in the second mold MD2. A limiting pin RP having a slightly reduced diameter is inserted through the circular opening CO. Accordingly, the transfer surface of the recess CB and the second mold MD2 is interposed between the circular opening CO that is the suction hole and the limiting pin RP (preferably with a gap of less than 0.01 to 0.03 mm on one side). The side is in communication. The amount of the gap can be adjusted by selecting limiting pins RP having different diameters and inserting them into the circular openings CO.

  In FIG. 5, a rectangular frame-shaped flange surface transfer surface FP and an inner film placement surface FL are formed on the end surface of the second mold MD2. A film-side optical surface OP arranged in 4 rows and 4 columns is formed in a film mounting surface FL that is planar (excluding the mold-side optical surface OP) as a whole, and is formed on the film mounting surface FL. The ends of the four circular openings CO are exposed between the corner and the mold-side optical surface OP closest thereto. The mold side optical surface is a surface of a mold having a shape for transferring a lens surface.

  A groove-like runner RN and a narrowed gate GT are formed so as to communicate with the flange surface transfer surface FP of the second mold MD2 from the outer periphery of the cavity member FR. Further, the cavity member FR is provided with a groove-like discharge path EX for releasing air in the cavity during molding extending along the outer periphery of the second mold MD2 and reaching the outer periphery of the cavity member FR. Yes.

  Further, the first convex portion PJ1 is formed in the central region on the film placement surface FL, and the second convex portion PJ2 is formed in the peripheral region closer to the outer periphery than the central region on the film placement surface FL. . In the present embodiment, the first convex portion PJ1 and the second convex portion PJ2 have the same shape, and an enlarged perspective view thereof is shown in FIG. More specifically, the convex portions PJ1 and PJ2 have a shape in which a conical portion CN is formed at the tip of a cylindrical portion CY extending from the film placement surface FL. However, a hemisphere or the like may be provided instead of the conical portion CN.

  Here, when the even-numbered mold-side optical surfaces OP are arranged at equal intervals, the “center region” refers to a plurality of mold-side optical surfaces OP closest to the center of the film mounting surface FL. It is preferable that it is between the mold side optical surfaces. Specifically, as shown in FIG. 8A, when the mold side optical surfaces OP are arranged at equal intervals in 4 rows and 4 columns, the “center region” is the most at the center of the film placement surface FL. It is preferable to be inside the smallest square AR1 in which corners are inscribed in the four adjacent mold-side optical surfaces OP. In this case, the “peripheral region” is a region other than the central region and a region other than the mold side optical surface OP (outside the square AR1). However, more preferably, the first convex portion PJ1 is desirably provided at the midpoint CP of the four mold side optical surfaces OP, and the second convex portion PJ2 is closest to the outer periphery of the film placement surface FL. It is desirable to provide the outer peripheral side of the square AR2 circumscribing the mold side optical surface OP.

  On the other hand, when the odd-numbered mold-side optical surfaces OP are arranged at equal intervals, the “center region” is the mold side closest to the center of the film mounting surface FL in the mold-side optical surface OP. It is preferable that it is between an optical surface and the mold side optical surface adjacent to it. Specifically, as shown in FIG. 8B, when the mold side optical surfaces OP are arranged at equal intervals in 3 rows and 3 columns, the “central region” is the most at the center of the film placement surface FL. It is preferable that the region is inside the smallest square AR3 in which corners are inscribed in four mold side optical surfaces OP adjacent to the near mold side optical surface OP and other than the mold side optical surface OP. At this time, the “peripheral region” is a region other than the central region (outside the square AR3) and a region other than the mold side optical surface OP. However, more preferably, the first protrusion PJ1 is within a circle having a radius (S / 2) from the optical axis of the central mold side optical surface OP, where S is the length of one side of the square AR3. The second protrusion PJ2 is preferably provided on the outer peripheral side of the square AR4 that circumscribes the mold side optical surface OP closest to the outer periphery of the film placement surface FL.

  Further, when the mold-side optical surfaces OP are arranged in an even number at equal intervals in the row direction (or column direction) and odd numbers are arranged at equal intervals in the column direction (or row direction), The “region” is preferably between the two mold side optical surfaces closest to the center of the film mounting surface FL in the mold side optical surface OP. Specifically, as shown in FIG. 8C, when the mold side optical surfaces OP are arranged at equal intervals in 4 rows and 3 columns, the two mold sides closest to the center of the film mounting surface FL It is preferable to be inside the circle AR5 inscribed in the mold side optical surface OP with the midpoint CP of the optical surface OP as the center. At this time, the “peripheral region” is a region other than the central region (outside the circle AR5) and a region other than the mold side optical surface OP. However, more preferably, the first convex portion PJ1 is desirably provided at the midpoint CP, and the second convex portion PJ2 circumscribes the mold side optical surface OP closest to the outer periphery of the film placement surface FL. It is desirable to provide on the outer peripheral side from the square AR6. By setting the span between the first convex portion PJ1 and the second convex portion PJ2 as large as possible, it is possible to achieve accurate positioning between the mold-side optical surface OP and the opening AP1. Regardless of the above, it is important for highly accurate positioning to arrange the convex portion PJ2 as far as possible to ensure a large span with the convex portion PJ1.

  Next, a method for manufacturing the optical element according to the present embodiment will be described. FIG. 9 is a diagram for explaining a process of insert-molding the first light shielding film SH1 and the first lens array LA1, and only the first mold MD1 and the second mold MD2 are shown in a simplified manner. FIG. 10 is a front view of the first light shielding film SH1. As a pre-preparation, a first light-shielding film SH1 having the shape shown in FIG. 10 is punched out from a film sheet made of a non-transparent (for example, light transmittance of 1% or less) resin material. More specifically, the first light-shielding film SH1 has an opening AP1 formed in 4 rows and 4 columns at the same pitch as the mold side optical surface OP, and a circular hole CH formed in the center, in the vicinity of one corner. A long hole LH is formed in the upper part. The longitudinal direction of the long hole LH faces the center of the circular hole CH.

  In FIG. 9A, the film placement surface of the second mold MD2 using a robot (not shown) in a state where the first mold MD1 is separated from the fixed second mold MD2. The first light-shielding film SH1 is attached to the FL (FIG. 5). More specifically, the first protrusion PJ1 of the second mold MD2 is inserted through the circular hole CH of the first light shielding film SH1, and the second protrusion PJ2 is inserted through the long hole LH. At this time, since the conical portion CN is provided at the tip of the convex portions PJ1 and PJ2, the insertion into the circular hole CH and the long hole LH can be performed smoothly.

  FIG. 11 is a diagram illustrating a state where the first light-shielding film SH1 is attached to the film placement surface FL of the second mold MD2. Here, since the circular hole CH and the first convex portion PJ1 are fitted with no gap, the origin positions in the X direction and the Y direction perpendicular to the film placement surface FL (the center O of the first convex portion PJ1). ) Is determined. Further, by fitting the elongated hole LH and the second convex portion PJ2, an angle around the origin O of the first light shielding film SH1 with respect to the film mounting surface FL (here, the axis L of the elongated hole LH passing through the origin O and the axis L) The crossing angle θ) with the Y axis is determined. In the case of a monocular optical system, the rotation of the light shielding member about the optical axis relative to the lens is not particularly problematic in positioning, but in the case of a lens array, the rotational position of the light shielding film is a major problem. According to the present embodiment, it is possible to accurately position the opening AP1 and the mold side optical surface OP. Even if a manufacturing error has occurred in the first light-shielding film SH1, since the mutual origin position O is fixed, at least the positions of the opening AP1 around the origin position O and the mold side optical surface OP are accurately determined. It will be. On the other hand, although the positions of the opening AP1 and the mold side optical surface OP around the film placement surface FL are slightly shifted from each other, the shift amount can be suppressed to a half or less of the manufacturing error of the first light shielding film SH1.

  At this time, since the first light-shielding film SH1 covers the circular opening CO, the first light-shielding film SH1 can be adsorbed and held on the film placement surface FL by suction from the external negative pressure source through the circular opening CO. it can.

  Next, as shown in FIG. 9B, the first mold MD1 is moved closer to the second mold MD2 to perform mold clamping. Thereafter, resin melted from the outside is supplied into the cavity CV formed by the second mold MD2 and the first mold MD1 through the runner RN and the gate GT (FIG. 5), and the influence of heat shrinkage. Is maintained at a predetermined pressure (60 to 70 MPa). Since the suction through the circular opening CO is continued while the resin is being supplied, the state where the first light shielding film SH1 is adsorbed and held on the film placement surface FL can be maintained, and the first light shielding film with respect to the film placement surface FL is maintained. The shift of SH1 can be suppressed.

  According to the present embodiment, since the gap between the circular opening CO and the limiting pin RP is small, the first light-shielding film SH1 is not broken by the pressure of the molten resin, and the circular opening CO It is possible to avoid the resin from entering and solidifying between the limit pin RP and becoming a burr or clogging that inhibits suction.

  In the present embodiment, the temperature of the resin supplied into the cavity CV is higher than the thermal deformation temperature of the first light shielding film SH1, and thereby the boundary surface with the first light shielding film SH1 is melted. It fuse | melts with the interface of the resin supplied in CV, and will join firmly by solidifying after that.

  Furthermore, as the supplied resin is solidified, the object side surface of the first lens portion L1 is transferred and formed by the mold side optical surface OP in the opening AP1 in the second mold MD2, and the flange surface transfer surface FP. The lens side surface in which the object side surface of the flange portion L1f is transferred, and at the same time, the image side surface of the first lens portion L1 and the image side surface of the flange portion L1f are transferred and formed by the first mold MD1, and the first light shielding film SH1 is joined. LA1 can be molded.

  Thereafter, as shown in FIG. 9C, the first mold MD1 is separated from the second mold MD2. At this time, since the tips of the convex portions PJ1 and PJ2 are conical surfaces, the molded product can be released more smoothly. In this state, as shown in FIG. 9 (d), the first lens array LA1 joined with the first light shielding film SH1 is projected from the first mold MD1 by projecting the projecting pin PR from the first mold MD1. Can be released from the mold. Thereafter, the molded product is transported to the next process by a robot (not shown), the ejection pin PR is retracted, and the process returns to the process of FIG. 9A. Thereafter, the same process is repeated.

  FIG. 12 is an enlarged view showing a part indicated by an arrow XII in FIG. As shown in FIG. 12, a taper shape in which a part of the resin forming the first lens array LA1 enters the circular hole CH of the first light shielding film SH1 and the first convex portion PJ1 is transferred and formed. 1st recessed part DP1 is formed. In addition, a tapered second concave portion in which a part of the resin forming the first lens array LA1 enters the elongated hole LH of the first light shielding film SH1 and the second convex portion PJ2 is transferred and formed. DP2 is formed. In the optical element to be a product, the concave portions DP1 and DP2 have no particular function, but the risk of ghosting can be further reduced as compared with the case where convex portions are provided.

  The second lens array LA2 to which the second light shielding film SH2 is bonded can also be manufactured by the same process. In this way, the first lens array LA1 joined with the first light shielding film SH1 and the lens array LA2 joined with the second light shielding film SH2 are laminated and fixed using an adhesive, and the third light shielding member SH3 is further fixed. Glue using an adhesive. Since the third light-shielding member SH3 is positioned closest to the image side in the lens unit LU, there is no significant influence on the light-shielding effect even if the third light-shielding member SH3 is separate from the second lens array LA2. It is good also as 3rd light-shielding member SH3 by carrying out insert molding of the manufactured film.

  FIG. 13 is a front view showing the first light-shielding film SH1 according to each modification. In the modified example of FIG. 13A, only the point that the long hole LH is provided at the center of the two openings AP1 in the vicinity of the center of one side of the first light shielding film SH1 with respect to the embodiment shown in FIG. Is different. 13 (b) differs from the embodiment shown in FIG. 10 only in that a notch CT is provided in the vicinity of the corner of the first light shielding film SH1 instead of the long hole. The longitudinal direction of the cutout CT faces the circular hole CH.

  Further, in the modified example of FIG. 13C, a long hole LH is provided at a position closer to the circular hole CH than the opening AP1 closest to the corner portion with respect to the embodiment shown in FIG. Only the difference. On the other hand, in the modified example of FIG. 13D, unlike the embodiment shown in FIG. 10, openings AP1 are formed in 3 rows and 3 columns corresponding to the optical surface of the first lens array (not shown). Yes. In the case of using this modification, in the second mold MD2, the first convex portion PJ1 cannot be arranged at the center of the film mounting surface FL in order to avoid the central mold side optical surface OP. The first convex portion PJ1 is provided in the vicinity of the central mold side optical surface OP, and the circular hole CH is provided in the vicinity of the central opening AP1 correspondingly. In addition, the long hole LH is similarly provided in the corner | angular part vicinity of 1st light shielding film SH1.

  FIG. 14 is an end view of the second mold MD2 according to the modification. According to this modification, four circular openings CO are added between the mold-side optical surfaces OP with respect to the above-described embodiment. Therefore, when the first light shielding film SH1 is placed on the film placement surface FL, a total of all eight circular openings CO are covered by the first light shielding film SH1. Thereby, when attracting | sucking through circular opening CO, the retention strength of 1st light shielding film SH1 increases. Other configurations are the same as those of the above-described embodiment.

  As an example, the inventors of the first light-shielding film having an outer shape of 8 mm × 8 mm and a thickness of 0.04 to 0.2 mm as shown in FIG. It was formed in 4 rows and a circular hole of φ0.8 mm and a long hole of 0.2 mm × 0.3 mm. On the other hand, the first convex portion and the second convex portion of the second mold have an outer diameter of φ0.2 mm, the height of which is higher than the thickness of the first light shielding film by 0.1 mm or more, A 0.08 mm fillet was formed at the tip. This first light-shielding film was attached to a second mold maintained at a mold temperature of 110 ° C., and the first lens array was injection molded. In this example, a positional shift of 0.004 to 0.008 mm occurred between the center of the opening and the optical axis of the lens, but it was found to be an allowable range.

  On the other hand, as a comparative example, a metal plate having the same shape as the first light-shielding film was attached to the second mold, and insert-molded into the first lens array under the same conditions. In the comparative example using this metal plate, the molded product was deformed with respect to the example. The reason is considered that the linear expansion coefficient of the metal is 1/3 or less of the linear expansion coefficient of the resin. The contraction of the member occurs from the release of the product to the room temperature, but when the metal plate is insert molded, the shrinkage rate of the resin is clearly higher, so the shrinkage on the side where the metal plate is not insert molded The amount is increased and the molded product is deformed to warp. From the above, the first light-shielding film is preferably a resin rather than a metal. More preferably, the linear expansion coefficients of the first light-shielding film and the first lens array are made closer to each other. Further, although depending on the thickness, it is more desirable that the Young's modulus of the first light-shielding film is smaller than the Young's modulus of the first lens array. As the material for the first lens array, COC, PC, or the like can be suitably used, and as the material for the first light shielding film, PET, PVF, PC, or the like can be suitably used. As an example, when the product name APEL manufactured by Mitsui Chemicals, Inc. is used as the material of the first lens array, the product name Soma Black of Somar Corporation can be used as the material of the first light shielding film.

  Further, the present inventors set the circular opening in the second mold to φ0.8 mm, insert a limiting pin having a different diameter, and set the clearance between the circular opening and the limiting pin to 0.01 mm, 0.03 mm, 0 on one side. The effect was confirmed by changing to 1 mm. At the time of molding, the pressure (holding pressure) of the resin supplied to the mold is increased to 60 MPa or more in order to compensate for the shrinkage of the resin and perform highly accurate transfer molding. Accordingly, if the clearance is too large, the resin is pushed into the gap, and the first light-shielding film may be deformed to cause the opening to be deformed or the resin to be cured in the gap.

  According to the experimental results of the present inventors, the film holding effect is sufficient in any case of the clearance between the circular opening and the limiting pin, but the first light-shielding film is deformed if it is 0.03 mm or less on one side. Thus, it has been found that the first light-shielding film can be appropriately held in the second mold without causing deformation of the opening and without causing hardening of the resin in the gap. Further, although the suction mark of the circular opening remains, since the circular opening is provided at a place other than the mold side optical surface, the optical performance is not affected. On the other hand, if the clearance between the circular opening and the limiting pin is 0.1 mm or more on one side, the first light-shielding film is pushed into the gap between the circular opening and the limiting pin when the holding pressure is high, although it depends on the thickness of the film. I found out that there is a risk of doing. At this time, it was found that the resin solidifies in the gap between the circular opening and the limiting pin, which requires disassembly and cleaning before the next molding, which hinders the production efficiency.

AD A / D converter AP1 Opening AP2 Opening AP3 Opening AP4 Opening AT Pedestal BS Back plate BT Bolt CA Imaging device CB Recess CH Circular hole CN Conical part CO Circular opening CP Midpoint CPU Control part CT Notch CU Imaging unit CV Cavity CY Cylindrical part DP Digital processing circuit DP1 1st recessed part DP2 2nd recessed part DR Extrusion mechanism DSP Image display part EX Discharge path F IR cut filter FL Film mounting surface FM Fixed mold unit FP Flange surface transfer surface FR Cavity Member GT Gate HD Adjustment plate HLD Mirror frame HLLa Peripheral wall HLDb Ceiling wall IF Interface IP Image processing circuit KY Operation key L1 First lens portion L1f Flange portion L2 Second lens portion L2f Flange portion LA1 First lens array LA2 Second Lens array LU Lens Uni G L1 Long hole MD1 1st mold MD1a Pin hole MD2 2nd mold MM Movable mold unit OP Mold side optical surface PJ1 1st convex part PJ2 2nd convex part PR Extrusion pin RD Recording part RP Restriction Pin SH1 1st light shielding film SH2 2nd light shielding film SH3 3rd light shielding member SH4 4th light shielding film SR Image pick-up element SS Light-receiving surface ST Circuit board

Claims (12)

An optical element formed by joining a film formed from a non-light-transmitting resin material and a lens array having a plurality of optical surfaces transferred by molding using a mold,
In the film, a circular hole, a long hole or notch whose longitudinal direction is the direction toward the circular hole, and a plurality of openings are formed,
The mold includes a plurality of mold side optical surfaces that transfer and form the optical surface, a mounting surface on which the film is mounted, and a first convex portion that is disposed in a central region of the mounting surface. A second convex portion disposed in a peripheral region closer to the outer periphery than the central region on the placement surface is formed,
In a state where each opening is positioned with respect to the mold side optical surface so that the first convex portion is inserted into the circular hole and the second convex portion is inserted into the elongated hole or notch. In addition, after the film is mounted on the mounting surface of the mold, the molten resin flows into the mold and is solidified to form the lens array, and the film is joined,
A first concave portion formed by transferring the first convex portion is formed in the circular hole, and the second convex portion is transferred after the resin is filled to the edge of the elongated hole or notch. An optical element in which a second recess is formed.   The optical element according to claim 1, wherein the Young's modulus of the film is smaller than the Young's modulus of the lens array.   In the film, a circular hole is formed in the film central region, and a long hole or a notch is formed in the peripheral region of the film with the direction toward the circular hole as a longitudinal direction. The circular hole is different from the long hole or the notch. The optical element according to claim 1, wherein a plurality of openings corresponding to a plurality of optical surfaces of the lens array are formed at a place.   When an even number of the mold side optical surfaces are arranged at equal intervals, the center region is a plurality of mold side optical surfaces closest to the center of the placement surface among the mold side optical surfaces. The optical element according to claim 1, which is between.   When the mold-side optical surfaces are arranged in an odd number at equal intervals, the center region includes a mold-side optical surface closest to the center of the placement surface among the mold-side optical surfaces, and The optical element according to claim 1, wherein the optical element is between adjacent mold-side optical surfaces. Said peripheral region, the optical element according to any There deviation of claims 1 to 5 than the closest mold side optical surface to the outer periphery of the mounting surface on the outside of the mold-side optical surface.   The optical element according to claim 1, wherein a part of the first recess and the second recess has a tapered shape. A method of manufacturing an optical element formed by bonding a film formed from a non-light-transmissive resin material and a lens array having a plurality of optical surfaces transferred by molding using a mold,
The mold includes a plurality of mold side optical surfaces that transfer and form the optical surface, a mounting surface on which the film is mounted, and a first convex portion that is disposed in a central region of the mounting surface. The second convex portion disposed in the peripheral region closer to the outer periphery than the central region on the placement surface, and a suction hole are formed,
The first convex portion is formed into the circular hole while bringing the film having a circular hole, a long hole or notch whose longitudinal direction is the direction toward the circular hole, and a plurality of openings to the mold. The film is inserted so as to cover the suction hole in a state where each opening is positioned with respect to the mold side optical surface so that the second convex portion is inserted through the elongated hole or notch. Is mounted on the mold,
Sucking and holding the film through the suction holes;
Clamp the mold,
Pour molten resin into the mold,
While shaping the lens array by solidifying the resin, the film is joined,
A first concave portion is formed by transferring the first convex portion into the circular hole, and the second convex portion is transferred after filling the resin into the edge of the elongated hole or notch. To form a second recess,
A method for manufacturing an optical element, wherein the optical element is released from the mold.   The optical element manufacturing method according to claim 8, wherein the Young's modulus of the film is smaller than the Young's modulus of the lens array.   In the film, the circular hole is formed in a film central region, and the elongated hole or notch whose longitudinal direction is a direction toward the circular hole is formed in a film peripheral region. The circular hole is separated from the elongated hole or notch. The method for manufacturing an optical element according to claim 8, wherein the plurality of openings corresponding to the plurality of optical surfaces of the lens array are formed at the location of the lens array.   The method for manufacturing an optical element according to any one of claims 8 to 10, wherein the mold is provided with the suction hole at a position different from the plurality of mold side optical surfaces.   The pin according to any one of claims 8 to 11, wherein a pin is inserted into the suction hole, and air is sucked through between the outer periphery of the pin and the inner periphery of the suction hole. A method for manufacturing an optical element.

Images