JP2013205587A - Optical unit and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation in optical performance of an optical unit due to the presence of foreign substances such as bubbles and dust caused by an adhesive in an optical path, and to join two optical members of the optical unit with high accuracy even when joining surfaces of the two optical members are curved surfaces.SOLUTION: A lens unit 1 as an optical unit includes at least two optical members, which are a first lens 11 and a second lens 12. The first lens 11 and the second lens 12 are joined with an adhesive sheet 13. The adhesive sheet 13 is in a sheet form having a stretching and contracting property.

Description

  The present invention relates to an optical unit that has at least two optical members (for example, lenses) and has the two optical members joined by an adhesive, and a method for manufacturing the optical unit.

  Conventionally, a small and thin imaging device has been mounted on a portable terminal which is a small and thin electronic device such as a mobile phone or a PDA (Personal Digital Assistant). Image information can also be transmitted to each other. An image pickup apparatus mounted on the portable terminal is required to have a high image quality as the penetration rate increases, and an image pickup apparatus including an image pickup device having a high number of pixels is required.

  A lens unit used in such an imaging apparatus is composed of a plurality of lenses, and each lens is required to be accurately positioned in both the optical axis direction and the optical axis orthogonal direction. In particular, with the increase in the number of pixels of the image sensor, that is, the reduction in the pixel pitch, the positioning has been required to have higher accuracy than before. In addition, strict positioning accuracy is also required between the lens and the lens frame that holds the lens, as described above.

  By the way, a lens used in an imaging apparatus is often resin-molded in order to obtain a degree of freedom in shape and dimensions and to reduce costs. However, since the lens is molded by a mold having a plurality of cavities, there is a minute dimensional variation for each cavity.

  For this reason, for example, when a lens unit is configured by joining two lenses with an adhesive, a cemented surface having a region orthogonal to the optical axis of one lens is orthogonal to the optical axis of the other lens. A joining surface having a region is directly brought into contact and joined, and the number of intervening parts is reduced to suppress variations in the lens interval.

  At this time, the positioning in the direction orthogonal to the optical axis is performed, for example, by bringing the cemented surfaces of the two lenses into contact with each other and aligning the two lenses to match the optical axes. After matching the optical axes, the two lenses are fixed with an adhesive and integrated to form a lens unit.

  The positioning in the optical axis direction is performed, for example, by bonding the bonding surfaces of two lenses with an adhesive mixed with fine particles. By such joining, the distance between the two lenses in the optical axis direction can be made constant according to the outer diameter size of the fine particles.

  By the way, although not joining two lenses, the structure which joins a lens and a lens-barrel using a liquid adhesive agent is disclosed by patent document 1. FIG. In Patent Document 1, an adhesive is poured into a gap between a cap that presses the flange portion of the lens and an inner surface of the lens barrel, and the adhesive is accumulated on the chamfered portion of the lens so that the lens is integrated with the lens barrel. It tries to become.

  In the backlight field of liquid crystal display devices, for example, as disclosed in Patent Document 2, a technique for joining two flat members (light diffusion layer, optical sheet) through an adhesive layer having a constant thickness is known. ing.

JP 2008-70484 A (refer to claim 1, paragraphs [0017], [0020], FIG. 1, FIG. 2, etc.) JP 2010-32907 A (refer to claim 1, paragraph [0022], FIG. 4 etc.)

  However, when the liquid adhesive in Patent Document 1 is applied to the bonding of two lenses, the liquid adhesive is fluid, so that when the adhesive is applied to the bonding surface, bubbles are formed on the surface of the adhesive. Or the adhesive may bite dust in the air at the same time as the adhesive is applied. When such foreign matters such as bubbles and dust are present in the optical path, the optical performance of the optical unit deteriorates.

  Further, in Patent Document 2, since two flat members are joined by an adhesive layer, a sheet-like adhesive layer having a constant thickness that does not deform before and after joining can be used as the adhesive layer at this time. However, since the adhesive layer is not deformed, it cannot be applied to the joining of two lenses having a curved joint surface (because the adhesive layer cannot be deformed along the curved surface). It cannot be joined with accuracy (so that the optical axis is not relatively inclined).

  In addition to joining the lenses, the above problem can occur in the same manner when joining the lens and another optical member (for example, a diaphragm disposed in the optical path).

  The present invention has been made to solve the above-mentioned problems, and its purpose is to suppress the deterioration of optical performance due to the presence of foreign matters such as bubbles and dust in the optical path due to the adhesive. It is another object of the present invention to provide an optical unit that can join the two optical members with high accuracy even if the joining surfaces of the two optical members are curved surfaces, and a method for manufacturing the optical unit.

  The optical unit of the present invention is an optical unit having at least two optical members and joining the two optical members with an adhesive, and the adhesive is composed of a sheet-like adhesive sheet having elasticity. It is characterized by having. The optical unit manufacturing method of the present invention is an optical unit manufacturing method for manufacturing an optical unit having at least two optical members and joining the two optical members with an adhesive. The two optical members are bonded using a sheet-like adhesive sheet having elasticity.

  Since the adhesive for joining the two optical members is a solid adhesive sheet and is not fluid, it is less likely to occur in the case of a fluid liquid adhesive. In other words, bubbles are reduced on the surface of the adhesive, and it is reduced that the adhesive bites the dust in the air simultaneously with the application of the adhesive. Thereby, it can suppress that foreign materials, such as a bubble and dust, exist in an optical path, and the optical performance of an optical unit deteriorates.

  In addition, since the adhesive sheet is sheet-like and has elasticity, even if the joint surface on the adhesive sheet side of one optical member is a curved surface, the thickness is almost uniform with respect to the joint surface. You can put the adhesive sheet along. Thereby, when joining two optical members with an adhesive sheet, it can suppress that the optical axis of each optical member inclines relatively, and can join two optical members with high precision.

  In the optical unit of the present invention, of the two optical members, one of the bonding surfaces on the adhesive sheet side may be a curved surface convex on the adhesive sheet side.

  In this case, when each optical member is bonded, the adhesive sheet extends so as to have a shape along the convex surface, and an adhesive layer having a substantially uniform thickness can be formed on the bonding surface. Therefore, the configuration of the present invention in which the adhesive sheet is expanded and contracted to join the two optical members is very effective.

  In the optical unit of the present invention, it is desirable that the adhesive sheet has a substantially uniform thickness in the range of 1 to 100 μm.

  In this case, since each optical member is joined via an adhesive sheet having a substantially uniform thickness, each optical member can be joined with high accuracy without being relatively inclined. Moreover, since the thickness of the adhesive sheet is as very thin as 1 to 100 μm, even if the surface of each optical member on the adhesive sheet side is a curved surface, the optical members are joined while reducing the occurrence of wrinkles on the adhesive sheet. be able to.

  In the optical unit of the present invention, the light transmittance of the adhesive sheet is desirably 95% or more.

  If the light transmittance of the adhesive sheet is as high as 95% or more, it is possible to suppress a significant decrease in light utilization efficiency due to use of the adhesive sheet.

  In the optical unit of the present invention, the adhesive sheet may be formed of a material that is cured by at least one of light and heat.

  In this case, the optical sheet can be bonded by curing the adhesive sheet with light (for example, ultraviolet rays) or heat.

  In the optical unit of the present invention, the refractive index of the adhesive sheet is desirably 1.45 to 1.6.

  In this case, the refractive index of the adhesive sheet is almost the same as the refractive index of general adhesives (including liquid adhesives). Easy to design.

  In the method for manufacturing an optical unit of the present invention, the adhesive sheet is disposed between the two optical members, and the two optical members are stretched along a convex surface that is a joint surface of one optical member. The two optical members may be joined by sandwiching the adhesive sheet.

  By stretching the adhesive sheet along the convex surface that is the joint surface of one optical member, it is possible to join the two optical members while suppressing wrinkles from forming on the adhesive sheet.

  In the manufacturing method of the optical unit of the present invention, after joining the two optical members with the adhesive sheet, the excess adhesive sheet protruding from the joint portion of the two optical members may be cut off.

  In this case, it is not necessary to prepare an adhesive sheet that matches the size (lens diameter) of each optical member included in the optical unit. That is, it is possible to cope with joining of optical members of various sizes with a single adhesive sheet.

  In the manufacturing method of the optical unit of the present invention, when the two optical members are respectively a first optical member and a second optical member, a first optical sheet in which a plurality of the first optical members are connected, A second optical sheet in which a plurality of second optical members are connected to each other is disposed so as to sandwich one adhesive sheet, and then the first optical sheet and the second optical sheet are connected to the first optical sheet. Each set of the optical member and the second optical member may be cut off, and the excess adhesive sheet protruding from the joint portion of the first optical member and the second optical member may be cut off.

  In this case, a plurality of optical units can be manufactured simultaneously using a single adhesive sheet, and mass production becomes possible.

  According to the present invention, since the adhesive for joining two optical members is a solid adhesive sheet, bubbles are generated on the surface of the adhesive, or the adhesive is in the air simultaneously with the application of the adhesive. Biting of dust is reduced, and it is possible to suppress the deterioration of the optical performance of the optical unit due to the presence of foreign matters such as bubbles and dust in the optical path.

  In addition, since the adhesive sheet is sheet-like and has elasticity, even if the bonding surface on the adhesive sheet side of the optical member is a curved surface, the adhesive sheet has a substantially uniform thickness on the bonding surface. Can be along. Thereby, each optical member can be joined with high precision, suppressing that the optical axis of each optical member inclines relatively.

It is sectional drawing which shows the schematic structure of the lens unit as an optical unit which concerns on one Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the said lens unit. It is sectional drawing which shows the manufacturing process of the said lens unit. It is sectional drawing which shows the manufacturing process of the said lens unit. It is sectional drawing which shows the manufacturing process of the said lens unit. It is sectional drawing which shows the manufacturing process in the case of manufacturing the said lens unit two or more simultaneously. It is sectional drawing which shows the other structure of the said lens unit. It is sectional drawing which shows other structure of the said lens unit.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration of a lens unit 1 as an optical unit of the present embodiment. The lens unit 1 has a first lens 11 and a second lens 12 as at least two optical members. The 1st lens 11 and the 2nd lens 12 are joined by the adhesive sheet 13 as an adhesive agent. In addition, the lens unit 1 may have a configuration in which three or more optical members are provided and adjacent optical members are bonded via an adhesive sheet.

  Both the first lens 11 and the second lens 12 are made of high-quality optical glass (for example, ABC glass manufactured by Nippon Electric Glass Co., Ltd.). It may be constituted by a lens material using a transparent polymer resin, or may be constituted by combining these.

  The first lens 11 has a convex optical surface on the adhesive sheet 13 side as the bonding surface 11a, and the second lens 12 has a concave optical surface on the adhesive sheet 13 side as the bonding surface 12a. Yes. The optical surface mentioned above is a surface that intersects with the optical axis AX of the lens unit 1 (the optical axes of the first lens 11 and the second lens 12), and optical action such as refraction with respect to incident light. Refers to the surface that affects In addition, the absolute value of the optical power of the bonding surfaces 11a and 12a may be the same or different.

  In order to impart optical performance to the lens unit 1, a light shielding portion (aperture) for blocking extra light rays on one or both optical surfaces of the first lens 11, an antireflection film, polarization A film, a physical coating film, or the like may be provided. Similarly, a light shielding portion or the like may be provided on one optical surface or both optical surfaces of the second lens 12.

  In the present embodiment, the lens unit 1 has, for example, a substantially cylindrical shape with a diameter of about 15 mm. However, the size and shape of the lens unit 1 are not particularly limited, and the effect of the present embodiment is limited. Not what you want.

  The adhesive sheet 13 is a sheet-like adhesive having elasticity. In the present embodiment, the adhesive sheet 13 is composed of an elastic acrylic ultraviolet curable adhesive sheet. Incidentally, the elastic modulus of the adhesive sheet 13 is desirably in the range of 0.001 to 1000 MPa, and is 0.05 MPa in the present embodiment. The thickness of the adhesive sheet 13 is 25 μm and is substantially uniform, the light transmittance of the adhesive sheet 13 is 99.8%, and the refractive index of the adhesive sheet 13 is 1.49.

  In the present embodiment, a light curable (ultraviolet curable) adhesive is used as the adhesive sheet 13, but a heat curable adhesive (adhesive sheet) may be used and is cured by both light and heat. It may be a light / thermosetting adhesive (adhesive sheet). As the thermosetting adhesive, for example, an adhesive made of imide or phenolic resin can be used. As the light / thermosetting adhesive, for example, an adhesive made of epoxy resin can be used.

  Next, the manufacturing method of the lens unit 1 of this embodiment is demonstrated. 2-5 is sectional drawing which shows the manufacturing process of the lens unit 1. As shown in FIG. First, as shown in FIG. 2, the above-described adhesive sheet 13 is disposed between the first lens 11 and the second lens 12. At this time, the adhesive sheet 13 is arranged with a certain degree of tension so that wrinkles do not occur on the surface. Although the arrangement | positioning method of the adhesive sheet 13 is not specifically limited, For example, the method etc. which arrange | position the adhesive sheet 13 while providing tension | tensile_strength by a roll-to-roll system etc. are mentioned.

  Subsequently, as shown in FIG. 3, the first lens 11 is moved to the adhesive sheet 13 side, the bonding surface 11 a of the first lens 11 is brought into contact with the bonding sheet 13, and the bonding sheet 13 is pressed, so that the bonding surface The adhesive sheet 13 is stretched along 11a (convex surface). Then, as shown in FIG. 4, the second lens 12 is moved to the adhesive sheet 13 side, the bonding surface 12 a that is the optical surface of the second lens 12 is brought into contact with the adhesive sheet 13 and pressed, and the first lens 12 is pressed. The adhesive sheet 13 is sandwiched between the lens 11 and the second lens 12. In the present embodiment, the adhesive sheet 13 is sandwiched and fixed with a pressure of about 10 N.

  Next, the adhesive sheet 13 is irradiated with ultraviolet rays of about 1000 mJ while the adhesive sheet 13 is sandwiched and fixed between the first lens 11 and the second lens 12. In this embodiment, a mercury lamp is used as the ultraviolet light source, but a halogen lamp, an LED light source, or the like may be used. Further, the order in which the first lens 11 and the second lens 12 are relatively brought closer is not particularly limited. However, as in the present embodiment, the first lens 11 and the second lens 12 have a bonding surface 11a that is convex on the adhesive sheet 13 side. By causing the adhesive sheet 13 to come into contact with the first lens 11 first, it is possible to reduce the occurrence of bubbles and wrinkles in the adhesive sheet 13. Moreover, you may perform the joining process of the 1st lens 11 and the 2nd lens 12 in a vacuum or a pressure-reduced state.

  Thus, after joining the 1st lens 11 and the 2nd lens 12 with the adhesive sheet 13, it protruded from the junction part of the 1st lens 11 and the 2nd lens 12, as shown in FIG. Excess adhesive sheet 13 is cut out with a die cutting blade 21. Thereby, the lens unit 1 shown in FIG. 1 is completed. In addition, although the cutting method of the unnecessary adhesive sheet 13 is not specifically limited, For example, you may make it cut | disconnect the unnecessary adhesive sheet 13 by pressing a lens part by a press work method.

  As described above, in the present embodiment, as an adhesive for joining the first lens 11 and the second lens 12, both are joined using the sheet-like adhesive sheet 13 having elasticity. . Since the solid adhesive sheet 13 is not fluid like a liquid adhesive, the generation of bubbles and the biting of dust that occurs when a liquid adhesive is used are less likely to occur. Thereby, it can suppress that foreign materials, such as a bubble and dust, exist in an optical path, and the optical performance of the lens unit 1 deteriorates. Moreover, application | coating while controlling the adhesive amount like the case where a liquid adhesive is used is unnecessary, and the process of wiping off an excessive adhesive agent is also unnecessary.

  Moreover, since the adhesive sheet 13 has a sheet shape and has elasticity, it can easily cope with the joining of lenses having irregularities. That is, as in the present embodiment, even if the joint surface 11a of the first lens 11 is a curved surface, the adhesive sheet 13 can be deformed and conformed to the joint surface 11a with a substantially uniform thickness. . Thereby, both can be joined with high accuracy via the adhesive sheet 13 without relatively tilting the optical axes of the first lens 11 and the second lens 12.

  In addition, since the bonding surface 11a of the first lens 11 is a curved surface that is convex toward the adhesive sheet 13, the first lens 11 and the second lens 12 are bonded when the first lens 11 and the second lens 12 are bonded to each other. The sheet 13 extends so as to have a shape along the convex surface. Thereby, an adhesive layer having a substantially uniform thickness can be formed on the bonding surface 13a. Therefore, the structure which joins both using the adhesive sheet 13 which has a stretching property becomes very effective.

  In addition, the adhesive sheet 13 is disposed between the first lens 11 and the second lens 12, and the first lens 11 is stretched along the convex surface that is the bonding surface 11 a of the first lens 11. By sandwiching the adhesive sheet 13 between the first lens 11 and the second lens 12, the adhesive sheet 13 can be bonded while suppressing wrinkles.

  Moreover, after joining the 1st lens 11 and the 2nd lens 12 with the adhesive sheet 13, the excess adhesive sheet 13 which protruded is cut off, and the 1st lens is used as the adhesive sheet 13 from the beginning. It is not necessary to prepare a lens that matches the size (lens diameter) of 11 or the second lens 12. Therefore, the single adhesive sheet 13 can cope with the joining of lenses of various sizes.

  In addition, when the thickness of the adhesive sheet 13 is as very thin as 1 to 100 μm and has a uniform thickness, the adhesive sheet 13 is wrinkled even if the bonding surface of the first lens 11 or the second lens 12 is a curved surface. It is possible to join them with high accuracy without tilting them while reducing generation. In this respect, in the present embodiment, since the thickness of the adhesive sheet 13 is 25 μm and uniform, the above effect can be obtained. In addition, since the adhesive sheet 13 is very thin as 100 μm or less, the lens unit 1 using the adhesive sheet 13 can be reduced in size, and even if the adhesive sheet 13 exists in the optical path, It is possible to reduce changes in optical characteristics.

  Moreover, if the light transmittance of the adhesive sheet 13 is as high as 95% or more, it is possible to prevent the light utilization efficiency from being greatly reduced by the use of the adhesive sheet 13. In this regard, in this embodiment, since the light transmittance of the adhesive sheet 13 is 99.8%, there is no problem in actual use regarding the light utilization efficiency.

  In addition, since the adhesive sheet 13 is formed of a material that is cured by at least one of light and heat, the adhesive sheet 13 is cured by light or heat, and the first lens 11 and the second lens 12 are bonded. Can be joined. Further, since the adhesive sheet 13 can be made sticky (adhesive) by light irradiation or heating only when necessary, for example, the adhesive sheet 13 is placed between the first lens 11 and the second lens 12. It is difficult for extra dust in the air to adhere to the surface of the adhesive sheet 13 simply by being disposed. In addition, when the adhesive sheet 13 is formed of a material that is cured by both light and heat, the first lens 11 and the first lens 11 are compared with a case where the adhesive sheet 13 is formed of a material that is cured by only one of light and heat. The second lens 12 can be more strongly fixed.

  Further, if the refractive index of the adhesive sheet 13 is 1.45 to 1.6 which is substantially the same as the refractive index of a general adhesive (including liquid adhesive), the design of the optical unit is the same as the conventional one. This makes it easy to perform optical design. In this respect, in this embodiment, since the refractive index of the adhesive sheet 13 is 1.49, it can be said that the optical design is easy even if the adhesive sheet 13 is used.

  By the way, although the case where the lens unit 1 was manufactured individually was demonstrated above, you may make it manufacture several lens unit 100 (optical unit) of a wafer level simultaneously. FIG. 6 is a cross-sectional view showing a manufacturing process when a plurality of lens units 100 are manufactured simultaneously. As shown in the figure, a first lens sheet 111 (first optical sheet) in which a plurality of first lenses 11 (first optical members) are connected, and a second lens 12 (second optical member). A plurality of second lens sheets 112 (second optical sheets) connected to each other may be arranged and bonded so as to sandwich one adhesive sheet 13 therebetween. After that, each set of the first lens 11 and the second lens 12 is cut out from the first lens sheet 111 and the second lens sheet 112 with a die cutting blade 21 (see FIG. 5), and further from the joint portion. You may make it cut off the excess adhesive sheet 13 which protruded with the die cutting blade 21 (refer FIG. 5).

  According to this method, for example, with respect to the adhesive sheet 13 having a width of 100 mm in the direction in which the first lenses 11 (second lenses 12) are arranged, the first lens 11 and the second lens 12 are set to 5 in the above direction. Using the first lens sheet 111 and the second lens sheet 112 connected to each of the six lens units, a plurality of lens units 100 can be simultaneously and easily manufactured. That is, it is possible to mass-produce a plurality of lens units 100 using a single adhesive sheet 13.

  In the above, the first lens 11 and the second lens 12 are bonded using the adhesive sheet 13 as it is (without processing). However, if necessary, the adhesive sheet 13 is processed in advance. In addition, the first lens 11 and the second lens 12 may be bonded using the processed adhesive sheet 13.

  FIG. 7 is a cross-sectional view showing another configuration of the lens unit 1. As shown in the figure, in the light-shielding adhesive sheet 13, an opening 13 a is formed in advance in a portion that becomes a light beam passing portion, and the first lens 11 and the second lens 12 are used by using the adhesive sheet 13. And may be joined.

  FIG. 8 is a cross-sectional view showing still another configuration of the lens unit 1. As shown in the figure, a diaphragm member 14 having an opening 14 a is disposed between the first lens 11 and the second lens 12, and the diaphragm member 14 and the first lens 11 are bonded with an adhesive sheet 13. In addition to bonding, the diaphragm member 14 and the second lens 12 may be bonded by the adhesive sheet 13. That is, the adhesive sheet 13 of this embodiment can be applied not only to the joining of two lenses but also to the joining of a lens and another optical member. The other optical member may be any optical member disposed in the optical path, and may be a spacer for controlling (adjusting) the lens interval in addition to the diaphragm member 14 described above.

  The present invention can be used for a lens unit of a small and thin imaging device mounted on a portable terminal such as a cellular phone or a PDA.

1 Lens unit (optical unit)
11 First lens (optical member, first optical member)
12 Second lens (optical member, second optical member)
13 Adhesive sheet 14 Diaphragm member (optical member)
100 Lens unit (optical unit)
111 1st lens sheet (1st optical sheet)
112 Second lens sheet (second optical sheet)

Claims (10)

An optical unit having at least two optical members, wherein the two optical members are joined with an adhesive,
The said adhesive agent is comprised with the adhesive sheet which has a sheet form and has a stretching property, The optical unit characterized by the above-mentioned.   The optical unit according to claim 1, wherein one of the two optical members has a bonding surface on the adhesive sheet side that is a curved surface that is convex toward the adhesive sheet.   The optical unit according to claim 1, wherein the adhesive sheet has a substantially uniform thickness in a range of 1 to 100 μm.   The optical unit according to claim 1, wherein the adhesive sheet has a light transmittance of 95% or more.   The optical unit according to claim 1, wherein the adhesive sheet is made of a material that is cured by at least one of light and heat.   The optical unit according to claim 1, wherein a refractive index of the adhesive sheet is 1.45 to 1.6. An optical unit manufacturing method for manufacturing an optical unit having at least two optical members and joining the two optical members with an adhesive,
A manufacturing method of an optical unit, wherein the two optical members are joined using a sheet-like adhesive sheet having elasticity as the adhesive.   By placing the adhesive sheet between the two optical members and extending the adhesive sheet along a convex surface that is a bonding surface of one optical member, the adhesive sheet is sandwiched between the two optical members, The method of manufacturing an optical unit according to claim 7, wherein two optical members are joined.   The method of manufacturing an optical unit according to claim 7 or 8, wherein after the two optical members are joined together by the adhesive sheet, the excess adhesive sheet protruding from the joint portion of the two optical members is cut off. . When the two optical members are respectively a first optical member and a second optical member,
A first optical sheet connecting a plurality of the first optical members and a second optical sheet connecting a plurality of the second optical members are arranged so as to sandwich one adhesive sheet, and then Cut out each set of the first optical member and the second optical member from the first optical sheet and the second optical sheet, and further join the first optical member and the second optical member The method of manufacturing an optical unit according to claim 7 or 8, wherein an excess of the adhesive sheet protruding from the edge is cut off.

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