JP2006308669A - Compound lens, method of manufacturing the compound lens, and optical apparatus with the compound lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound lens which has high dimentional precision and has no damage concerns occurring in a lens base body, first resin layer and second resin layer, to provide a method of manufacturing the compound lens, and to provide an optical apparatus with the compound lens. <P>SOLUTION: In the compound lens in which the first resin layer made by curing ultraviolet curable resin and a second resin layer are successively formed on a lens base body, the second resin layer is formed so as to cover the first resin layer and the outermost margin of the radial direction of the first resin layer is extended to the outside of effective diameter. Preferably the film thickness within effective diameter of the second resin layer is made to be 2 to 10 μm. Further, the thickness of the maximum thickness part outside the effective diameter of the second resin layer is preferably ≥20 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging lens system used for a digital camera, a mobile phone, etc., a lens for optical pickup, or a compound lens applied to a converging / diverging lens for optical communication, a method for producing the compound lens, and The present invention relates to an optical apparatus provided with the compound lens.

  For example, one or more lenses are used in optical devices such as digital cameras, mobile phones, optical pickups, and optical communication devices. If a spherical lens is used as the lens, the focal length becomes long, so the optical system becomes large, and this has been an obstacle to the reduction in size and weight of optical equipment required by the market. Therefore, a spherical lens made of glass or transparent plastic is used as a lens base, and a composite lens that functions as an aspherical lens is formed by forming an ultraviolet curable resin layer on the surface thereof, and the composite lens is provided in the optical system. The focal length was shortened to reduce the size of the optical system, that is, to reduce the size of the optical apparatus.

  A conventional conventional compound lens is shown in FIG. As can be seen from FIG. 6, in the conventional compound lens 1a, the first resin layer 31 is formed on one main surface of the lens base 2, and the second resin layer 32 is further formed on the first resin layer. Is formed.

  A manufacturing process of a conventional compound lens will be described with reference to FIG.

  First, a glass substrate 2 made of a biconvex spherical lens made of glass or transparent plastic is prepared. As shown in FIG. 5A, a predetermined amount of the first resin liquid 31L, which is an ultraviolet curable resin solution, is applied to the recesses 451 of the mold 45 for resin layer formation. Next, the lens base 2 is pressed against a predetermined position of the concave portion 451 of the mold 45 as shown in FIG. As a result, the first resin liquid 31L is filled in the space between the surface of the recess 451 of the mold 45 and the lens base 2 without any gap.

  Thereafter, when ultraviolet rays (indicated by arrows) are irradiated from the lens base 2 side, the ultraviolet rays pass through the lens base 2 and reach the first resin liquid 31L, thereby curing the first resin liquid 31L. The first resin liquid 31L is cured to become the first resin layer 31, but the shape change or sink occurs due to the shrinkage that occurs during the curing, and between the first resin layer 31 and the concave portion 451 of the mold 45. There is a gap 31S.

  Since the resin layer in this state cannot obtain satisfactory optical characteristics as a composite lens, a method of further forming a resin layer so that the resin layer has a desired shape has been employed. (See Patent Documents 1 and 2).

  That is, the lens base 2 (hereinafter referred to as the lens primary molded product 11) on which the first resin layer 31 is formed is removed from the mold 45, and an ultraviolet curable resin solution is placed in the recess 451 of the mold 45 as shown in FIG. A predetermined amount of a second resin liquid 32L is applied. Next, as shown in FIG. 4E, the lens primary molded product 11 is pressed against a predetermined position of the concave portion 451 of the mold 45. Thereby, the second resin liquid 32L is filled in the gap 31S between the surface of the concave portion 451 of the mold 45 and the lens primary molded product 11 without a gap. Thereafter, when ultraviolet rays (indicated by arrows) are irradiated from the lens base 2 side for 10 minutes, the ultraviolet rays pass through the lens base 2 and the first resin layer 31 to reach the second resin liquid 32L, and the second resin liquid. Cure 32L. As shown in FIG. 5F, the second resin liquid 32L is cured to become the second resin layer 32.

Next, when the lens base 2 on which the first and second resin layers 31 and 32 are formed is removed from the mold 45, the conventional compound lens 1a shown in FIG. 6 is completed.
JP 60-56544 A JP-A-1-171932

Since the same mold 45 is used for forming the first resin layer (first formation) and the second resin layer (second formation), the mold 45 and the lens primary molded product 11 are used in the second molding. Cannot be brought into contact with each other accurately. Therefore, when the lens primary molded product 11 stops before the predetermined position of the mold 45, the thickness of the second resin layer 32 becomes larger than a predetermined amount, or the second resin layer 32 has a second relative to the optical axis of the lens base 2. There was a problem that the resin layer 32 was easily eccentric.

  In addition, since the thin resin layer is formed in the second formation, the shrinkage amount of the second resin liquid 32L is small, but the second resin layer 32 and the mold 45 are easily adsorbed, and the first and second resins. When the lens base 2 on which the layers 31 and 32 are formed is released from the mold 45, a large force is required, and the lens base 2, the first resin layer 31, and the second resin layer 32 may be damaged. there were.

  Accordingly, the present invention provides a compound lens that has high dimensional accuracy and does not cause damage to the lens substrate, the first resin layer, and the second resin layer, a method for manufacturing the compound lens, and an optical device including the compound lens. The purpose is to provide equipment.

  The first invention is a composite lens in which a first resin layer and a second resin layer formed by curing an ultraviolet curable resin on a lens substrate in order, wherein the second resin layer includes the first resin layer. The outermost edge in the radial direction of the first resin layer is a compound lens that extends to the outside of the effective diameter.

  The film thickness within the effective diameter of the second resin layer is preferably 2 to 10 μm.

  It is preferable that the thickness of the maximum thickness portion outside the effective diameter of the second resin layer is 20 μm or more.

  Air bubbles or sink marks may exist in at least a part of the second resin layer outside the effective diameter.

  The first resin layer and the second resin layer may be made of the same resin.

  According to a second aspect of the present invention, there is provided a step of applying a first resin liquid to the lens base or the concave portion of the first mold, a step of pressing the lens base and the first die, and a first resin irradiated with ultraviolet rays. A step of curing the liquid to form a first resin layer; a step of removing the lens base on which the first resin layer is formed from the first mold; and the formed first resin layer or second mold. A step of applying the second resin liquid to the recess, a step of irradiating the ultraviolet ray to cure the second resin liquid to form the second resin layer, and the first and second resin layers are formed. And removing the lens base from the second mold, wherein the concave part of the second mold corresponding to the second resin layer corresponds to the first mold corresponding to the first resin layer. The second mold so that the second resin layer is formed so as to cover the first resin layer. Recess is the preparation method of the compound lens has a shape which encloses the recess of the first type.

  The material of the concave surface of the first mold can be different from the material of the concave surface of the second mold.

  A third invention is an optical apparatus including the compound lens of the first invention.

  The following effects are achieved by the present invention.

  Since the first resin layer formed first is enclosed in the recess of the second mold used in the second resin layer formation, that is, smaller than the recess of the second mold, the second resin layer In the layer molding, the lens base on which the first resin layer is molded can be accurately pressed against the concave portion of the second mold. Therefore, an error in the thickness of the second resin layer and an eccentricity of the second resin layer with respect to the optical axis of the lens base can be avoided.

  Since the film thickness within the effective diameter of the second resin layer is as thin as 2 to 10 μm, the amount of resin shrinkage within the effective diameter can be kept small when forming the second resin layer. A desired surface shape can be obtained in a region within the effective diameter where shape accuracy is required.

  Since the film thickness of the maximum thickness portion outside the effective diameter of the second resin layer is set to 20 μm or more, the amount of shrinkage increases in the portion, and the second resin layer is easily released from the second mold.

  If the applied amount of the second resin liquid is slightly less than the volume of the space between the surface of the concave portion of the second mold and the lens primary molded body, the thickness of the second resin layer increases. In this case, bubbles and sink marks are likely to be generated, so that release is easy.

  The surface shape of the second resin layer is required to be accurate, but the surface shape of the first resin layer is not required to be accurate. Therefore, if at least the concave portion of the first mold is made of a material that can be easily released, such as tetrafluoroethylene resin, with an emphasis on releasability, the lens substrate on which the first resin layer is formed can be used as the first mold. Can be easily removed.

Accordingly, since the mold release is easier than in the conventional manufacturing method, there is no possibility of damaging the lens base, the first resin layer, and the second resin layer. If an optical device such as a mobile phone, an optical pickup, or an optical communication device is provided, the optical device can be downsized.

  The embodiment of the present invention will be specifically described by way of examples.

  A cross-sectional view of the compound lens 1 of the example is shown in FIG. The compound lens 1 covers a biconvex spherical lens-shaped lens base 2 made of glass, a first resin layer 31 formed on one main surface of the lens base 2, and the first resin layer 31. And the formed second resin layer 32. The outermost edge in the radial direction of the first resin layer 31 extends to the outside of the effective diameter D (= 2.6 mm).

  A method for manufacturing the compound lens of the example will be described below.

  First, the ultraviolet curable resin solution used as the 1st and 2nd resin layer is prepared in the following procedures. After mixing 5.5 ml of 3-methacryloxypropyltriethoxysilane (MPTES), 20.5 ml of ethanol, 1.65 ml of hydrochloric acid (2N), and 3.75 ml of phenyltrimethoxysilane, the mixture was allowed to stand at 24 ° C. for 72 hours and then irradiated with ultraviolet rays. In order to accelerate curing, 1 wt% of 1-hydroxy-cyclohexyl-phenyl-ketone, which is a photopolymerization initiator, was mixed and heated at 100 ° C. for 1 hour to evaporate ethanol to prepare an ultraviolet curable resin solution.

  Next, a process of forming the first and second resin layers on the lens base will be described with reference to FIG.

  A commercially available glass material BK-7 is polished to produce a glass substrate 2 composed of a biconvex spherical lens having a diameter of 3.6 mm and a curvature radius of 7.3 mm as shown in FIG. A silane coupling agent is applied to the surface of the glass substrate 2 in order to improve adhesion with the resin.

  Here, the 1st type | mold 41 for forming a 1st resin layer is prepared. The first mold 41 is made of a material that can be easily released, such as tetrafluoroethylene resin, at least at a portion corresponding to the first resin layer. First, a fluorine release agent is applied to the first mold 41. Then, a predetermined amount of the first resin liquid 31L made of the ultraviolet curable resin solution is applied to the recess 411 of the first mold 41 so that bubbles do not enter. Next, as shown in FIG. 2B, the lens base 2 is pressed against the first mold 41 while the center of the lens base 2 and the center of the recess 411 are accurately aligned. As a result, the first resin liquid 31L is filled in the space between the surface of the recess 411 of the first mold 41 and the lens base 2 without any gap. Thereafter, ultraviolet rays (indicated by arrows) are irradiated for 10 minutes from the lens base 2 side, whereby the first resin liquid 31L is cured and the first resin layer 31 is formed as shown in FIG. . The thickness of the first resin layer 31 is 15 μm at the optical axis portion, 130 μm at the outer edge portion of the effective diameter, and 130 μm outside the effective diameter portion.

  Next, the lens substrate 2 on which the first resin layer was formed (hereinafter referred to as a lens primary molded body 11) was removed from the first mold 41, placed in a thermostat at 120 ° C., and heat-aged for 6 hours.

  Here, the 2nd type | mold 42 for forming a 2nd resin layer is prepared. Unlike the first mold, the second mold 42 is made of nickel because the accuracy of the surface shape of the formed second resin layer is more important than the releasability. The concave portion 421 of the second mold 42 corresponding to the second resin layer 32 is different in shape from the concave portion 411 of the first mold 41 corresponding to the first resin layer 31, and the second resin layer 32 is The concave portion 421 of the second mold 42 has a shape including the concave portion 411 of the first mold 41 so as to cover the first resin layer 31. A fluorine-based mold release agent is applied to the second mold 42. As shown in FIG. 4D, a predetermined amount of the second resin liquid 32L made of the ultraviolet curable resin solution is applied to the recess 421 of the second mold 42 so that bubbles do not enter. If the applied amount is slightly less than the volume of the space between the surface of the concave portion 421 of the second mold 42 and the lens primary molded body 11, the effective diameter that increases the thickness of the second resin layer 32. Since bubbles and sink marks are easily generated outside, it is effective for mold release.

  Next, as shown in FIG. 5E, the lens primary molded body 11 is pressed against the second mold 42 while the center of the lens primary molded body 11 and the center of the concave portion 421 are accurately aligned. As a result, the second resin liquid 32L fills the space between the surface of the concave portion 421 of the second mold 42 and the lens primary molded body 11 without a gap. Thereafter, ultraviolet rays (indicated by arrows) are irradiated for 10 minutes from the lens base 2 side, whereby the second resin liquid 32L is cured and the second resin layer 32 is formed as shown in FIG. .

  Next, the lens base 2 on which the first and second resin layers 31 and 32 are formed is removed from the second mold 42, placed in a constant temperature bath at 120 ° C., and heat-aged for 6 hours, as shown in FIG. The compound lens 1 of the example is completed.

  In order to optimize the effective inner diameter film thickness T1 of the second resin layer, several types of compound lenses were manufactured and the characteristics were examined. Specifically, since it is difficult to produce an effective diameter inner film thickness T1 of less than 2 μm, a prototype of 2 to 20 μm is fabricated, and the surface shape of the compound lens, that is, the formed second resin The amount of deviation from the design value (hereinafter referred to as PV value) was measured for the surface shape of the layer. The result is shown in FIG. As can be seen from the figure, when the effective inner diameter film thickness T1 is reduced, the PV value is also reduced, and when the effective inner diameter film thickness T1 is 10 μm or less, the PV value is 0.5 μm or less. . If the PV value is 0.5 μm or less, the aberration is hardly affected. Therefore, it can be seen that the effective inner diameter T1 of the second resin layer is preferably 2 to 20 μm.

  Next, in order to optimize the maximum thickness portion film thickness T2 outside the effective diameter of the second resin layer, several types of compound lenses were prototyped and the characteristics were examined. Specifically, an effective outside diameter maximum thickness portion film thickness T2 was made as a prototype of 0 to 50 μm. Here, the film thickness T2 of 0 μm corresponds to a conventional compound lens.

  In order to confirm the force required to release the lens base 2 on which the first and second resin layers 31 and 32 are formed from the second mold 42, the first and second resin layers 31 and 32 are formed. The peel strength of the lens substrate 2 thus formed with respect to the second mold 42 was measured. The result is shown in FIG. As can be seen from the figure, when the effective outside maximum thickness portion film thickness T2 is in the range of about 0 to 20 μm, the peel strength decreases as the effective outside diameter maximum thickness portion film thickness T2 increases. If the outermost maximum thickness portion film thickness T2 is 20 μm or more, the peel strength is approximately constant at about 0.25 to 0.30 kg. If the peel strength is 0.5 kg or less, the lens base 2 on which the first and second resin layers 31 and 32 are formed can be easily released from the second mold 42. Therefore, it can be seen that it is preferable to set the outer diameter maximum thickness portion film thickness T2 of the second resin layer to 20 μm or more.

  The present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications without departing from the scope of the invention.

  For example, in the embodiment, the first and second resin layers 31 and 32 are formed only on one main surface of the lens base 2. However, as shown in FIG. Two resin layers 31 and 32 may be formed. The lens base 2 is not limited to a biconvex lens, and any of a biconcave lens, a meniscus lens, a planoconvex lens, and a planoconcave lens may be used.

  In the manufacturing method in the example, the lens base or the lens primary molded body was pressed against the mold after the resin liquid was applied to the mold, but the resin liquid was applied to the first resin layer formed on the lens base or the lens base. The lens base or the lens primary molded body may be pressed against the mold after applying the above.

  Further, although the mold in the embodiment has only one concave portion, it is also possible to have a plurality of concave portions. With such a configuration, a plurality of compound lenses can be manufactured at one time. There is an advantage.

  According to the present invention, there is provided a compound lens that has high dimensional accuracy and does not cause damage to the lens substrate, the first resin layer, and the second resin layer, a method for manufacturing the compound lens, and an optical apparatus including the compound lens. It becomes possible to provide.

It is sectional drawing of the compound lens of the Example which concerns on this invention. It is a partial process figure of the compound lens of the Example which concerns on this invention. It is sectional drawing of the compound lens of the other Example which concerns on this invention. It is a figure which shows the relationship between the effective diameter inner film thickness T1 of a 2nd resin layer, and PV value. It is a figure which shows the relationship between the film thickness T2 of the largest thickness part outside the effective diameter of a 2nd resin layer, and peeling strength. It is sectional drawing of the conventional compound lens. It is a partial process figure of the conventional compound lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Composite lens 11 ... Lens primary molded object 2 ... Lens base body 31 ... 1st resin layer 31L ... 1st resin liquid 32 ... 2nd resin layer 32L ... 2nd resin liquid 41 ... 1st type | mold 411 ... Concave part 42 ... 2nd type | mold 421 ... Concave part

Claims (8)

  In the composite lens in which the first resin layer and the second resin layer are sequentially formed by curing the ultraviolet curable resin on the lens base, the second resin layer is formed to cover the first resin layer. The composite lens, wherein the outermost edge in the radial direction of the first resin layer extends to the outside of the effective diameter.   2. The composite lens according to claim 1, wherein a film thickness of the second resin layer within an effective diameter is 2 to 10 μm.   3. The compound lens according to claim 1, wherein the thickness of the maximum thickness portion outside the effective diameter of the second resin layer is 20 μm or more.   The composite lens according to claim 1, wherein bubbles or sink marks are present in at least a part of the second resin layer outside the effective diameter.   5. The compound lens according to claim 1, wherein the first resin layer and the second resin layer are made of the same resin. A step of applying the first resin liquid to the lens base or the concave portion of the first mold; a step of pressing the lens base and the first mold; and curing the first resin liquid by irradiating ultraviolet rays. Forming the first resin layer; removing the lens base on which the first resin layer is formed from the first mold; and forming the second resin in the concave portion of the formed first resin layer or second mold. A step of applying a resin solution, a step of irradiating ultraviolet rays to cure the second resin solution to form a second resin layer, and a second lens substrate on which the first and second resin layers are formed. Removing the mold from the mold, and a method of manufacturing a compound lens comprising:
The concave portion of the second mold corresponding to the second resin layer is different in shape from the concave portion of the first mold corresponding to the first resin layer, and the second resin layer covers the first resin layer. A method of manufacturing a compound lens, wherein the concave portion of the second mold has a shape including the concave portion of the first mold so that the concave portion of the second mold is formed.   7. The method of manufacturing a composite lens according to claim 6, wherein the material of the concave surface of the first mold is different from the material of the concave surface of the second mold. An optical apparatus comprising the compound lens according to claim 1.

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