JP2007199107A - Lens and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens in which the dimensional accuracy of a lens surface can be evaluated more easily and accurately, and the control of the accuracy of which can be easily performed. <P>SOLUTION: The lens 1 is equipped with a lens effective part 5 forming the lens surface with an optical axis 2 as center, an edge part 6 of doughnut shape in plane view which is extended along the outer periphery thereof, and angle parts 3, 4a and 4b annular in plane view with the optical axis 2 as center which are formed on both sides thereof. The lens effective part 5, the edge part 6 and the angle parts 3, 4a and 4b are integrally and simultaneously molded. The angle parts 3, 4a and 4b are formed of a recessed part 4 or a projection part 8 annular and belt-shaped in plane view. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens used in an imaging device built in a mobile phone with a camera or a mobile terminal, and an imaging device using the lens.

  This type of lens needs to be mass-produced at low cost and with high accuracy by, for example, injection molding of a transparent optical resin. In many cases, a plurality of lenses are used in combination. In Patent Document 1, in an optical lens such as an objective lens of an optical pickup, for example, a configuration that facilitates centering of a combination lens by providing a mark concentrically with a lens effective diameter portion outside the lens effective diameter. Is described. In addition, a method for facilitating phase alignment of a plurality of lenses by combining convex portions and concave portions provided on the surface of the outer portion of the lens effective diameter is described.

Further, in Patent Document 2, when a plurality of lenses are used in combination with an objective lens of an optical pickup, a mark representing a mold cavity formed with the lens is provided on the lens, and a smooth portion provided on the upper lens is passed through. A configuration is described in which the mark on the lower lens can be identified.
JP 2002-71909 A JP 2004-205823 A

  The prior art as described above is for realizing improvement in positional accuracy between lenses and improvement in assembly workability when a plurality of lenses are used in combination with an objective lens of an optical pickup. On the other hand, image pickup apparatuses used for camera-equipped mobile phones and the like have been downsized, and the lenses used therefor are also required to be downsized and thinned. In addition, with the increase in the number of pixels of the image sensor, the optical characteristics required for the lens are becoming increasingly severe. With respect to a single lens, particularly when the lens surface is aspheric, the optical characteristic data is measured using an AFM (Atomic Force Microscope) or the like, and the aspherical design data is molded. Measuring the shape of the lens. By performing best fitting and its evaluation, a high-precision and high-performance lens is realized.

  Further, since the center deviation (referred to as decentering or decentering) of the lens surfaces on the front and back sides of a single lens has a large effect on the performance, it is necessary to measure with great care. When such a measurement is evaluated for each forming lot, a great amount of labor is required. In addition, when the evaluation result based on the measurement data is not good, it is necessary to review or reset the molding conditions and the like, which becomes a factor that hinders the improvement of productivity.

  The present invention solves the above-described conventional problems, makes it possible to more easily and accurately evaluate the dimensional accuracy of the lens surface, and to use a lens that can easily manage the accuracy of the lens. An object of the present invention is to provide an image pickup apparatus.

  The lens according to the present invention is formed on both surfaces of the lens effective portion that forms a lens surface around the optical axis, a donut-shaped edge portion in plan view extending on the outer periphery of the lens effective portion, and the edge portion. An annular corner portion in plan view with the optical axis as a center is provided, and the lens effective portion, the edge portion, and the corner portion are integrally and simultaneously molded.

  In the lens of the present invention, when the edge portion is irradiated with parallel light, a plurality of annular lines corresponding to the annular corner portions can be observed in a plan view centered on the optical axes formed on both surfaces of the edge portion. When the accuracy of the lens surface is reduced due to various conditions such as pressure, temperature, and time at the time of molding the lens, the factor is also reflected in the annular corner portion formed in the edge portion. Therefore, by evaluating the eccentricity of a plurality of annular lines corresponding to the annular corners, the dimensional accuracy such as the eccentricity of both lens surfaces can be easily evaluated. Thereby, management of the dimensional accuracy of the lens can be easily realized.

  In a preferred embodiment of the lens of the present invention, the annular corners are formed at substantially equal radius positions centered on the optical axis on both sides of the edge portion. According to this configuration, if an annular line corresponding to each of the annular corners formed on both sides of the edge portion can be observed as one circle, it is estimated that there is no eccentricity between both sides and the accuracy is high. Can do. That is, it is possible to visually determine the presence or absence of eccentricity without measuring dimensions such as roundness.

  In another preferred embodiment of the lens of the present invention, an annular and band-shaped recess is formed on at least one surface of the edge portion in plan view, and an angle formed by a bottom surface and a side surface of the recess corresponds to the corner portion. According to this configuration, two concentric corners can be obtained by forming an annular and band-like recess in plan view, and the position between both surfaces can be determined from the positional relationship with the annular corner formed on the opposite surface. Visual evaluation of the eccentricity of the image becomes easy.

  In another preferred embodiment of the lens of the present invention, an annular and band-like projection is formed on at least one surface of the edge portion, and the angle formed by the side surface of the projection and the surface of the edge portion is the angle. It corresponds to the part. According to this configuration, two concentric corners can be obtained by forming the annular and belt-like projections in plan view, and both sides can be obtained from the positional relationship with the annular corner formed on the opposite surface. Visual evaluation of the eccentricity between them becomes easy.

  In another preferred embodiment of the lens of the present invention, the tip surface of the protrusion protrudes in the optical axis direction from the lens surface. According to this configuration, for example, when a lens is placed on a flat table, it is possible to prevent the lens surface from coming into direct contact with the flat table by placing the projecting portion downward. Convenient to.

  In another preferred embodiment of the lens of the present invention, a planar view annular and belt-like recess is formed in the vicinity of the planar view annular and belt-like projection. According to this configuration, when the back coating agent is applied to the outer peripheral surface of the edge portion of the lens and the lenses are fixed to each other or the lens and the lens barrel are fixed, the annular and belt-shaped concave portion in plan view is excessively bonded. It functions as a reservoir of agent. The protrusion functions as a bank to prevent the adhesive from entering the inner peripheral side (lens effective portion). This stabilizes the quality of the lens assembly and improves the yield.

  The image pickup apparatus of the present invention includes the lens as described above and a semiconductor image pickup device that receives the light collected by the lens and outputs an electric signal of an image formed. Thereby, it is possible to realize a small and inexpensive imaging device having excellent optical characteristics by using a lens with high dimensional accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram schematically showing a lens according to the first embodiment of the present invention. 1A is a plan view of the lens as viewed from the optical axis direction, and FIG. 1B is a cross-sectional view of the lens of FIG. 1A taken along line XX. In FIG. 1B, the lens effective portion 5 is formed of a left lens surface R1 and a right lens surface R2.

  As shown in FIG. 1, the lens 1 of the present embodiment includes a lens effective portion 5 having a biconvex lens shape around the optical axis 2, a planar donut-shaped edge portion 6 extending on the outer periphery thereof, An inlay portion 8 that protrudes in an annular shape centered on the optical axis 2 from the one surface (the surface on the lens surface R2 side) is provided. The inlay portion 8 corresponds to a projection having a band shape in plan view. The lens effective portion 5, the edge portion 6 and the inlay portion 8 are integrally and simultaneously molded with resin. As a resin material, for example, ZEONEX (registered trademark) E48R manufactured by Nippon Zeon Co., Ltd. can be used. In order to obtain predetermined optical characteristics, the lens effective portion 5 is designed to be an aspherical lens having an aspherical shape that is axisymmetric with respect to the optical axis 2. Properties such as the refractive index and transmittance of the material are appropriately selected according to the optical properties required for the lens 1.

In this embodiment, the lens 1 is manufactured by resin molding. However, the present invention is applied to a lens manufactured by a glass mold using optical glass or a hybrid lens having a resin layer formed on a spherical glass. Is also possible. Further, at least on the surface of the lens effective portion 5, one or more thin films such as magnesium fluoride (MgF ₂ ) and silicon dioxide (SiO ₂ ) having different refractive indexes are used as an AR (Anti Reflection) coat for preventing reflection. About 4 layers are deposited.

  As will be described later, a lens unit formed by coupling two lenses having slightly different shapes is incorporated in the lens barrel portion of the imaging apparatus to form a predetermined imaging optical system. That is, an imaging system is configured such that light incident on the lens effective portion 5 is collected at a predetermined position (light receiving surface of the solid-state imaging device). At this time, the edge portion 6 and the inlay portion 8 of the lens 1 function as a fitting portion when the two lenses are coupled, and also have a function for positioning and fixing the lens unit with respect to the lens barrel portion. Have. Both sides (surfaces perpendicular to the optical axis) of the edge portion 6 are formed to be two parallel and smooth planes.

  An annular corner 3 is formed by the side surface of the inlay portion 8 and the surface of the end portion 6 at the base portion of the inlay portion 8 corresponding to the projection portion having a band shape in plan view formed on the end portion 6. Further, the other surface (surface on the lens surface R1 side) of the edge portion 6 is formed with an annular and band-shaped concave portion 4 in plan view, and the outer corner portion 4a and the inner peripheral side are formed by the bottom surface and both side surfaces. Corners 4b are formed. The concave portion 4 is formed at the same time when the lens effective portion 5, the edge portion 6 and the inlay portion 8 are molded. In this embodiment, it arrange | positions so that the corner | angular part 3 formed by the base of the spigot part 8 may be pinched | interposed between the corner | angular part 4a of the outer peripheral side formed by the recessed part 4, and 4b of the inner peripheral side. These annular corners 3, 4 a and 4 b have a function of making it possible to easily check the eccentricity of the lens surfaces R 1 and R 2 of the lens 1. In the mold processing, the annular grooves 3, 4a, 4b corresponding to the R1 surface and the R2 surface of the lens effective portion 5 are formed by simultaneous processing so that the accuracy can be sufficiently high. Before describing the function, a description will be given of resin molding of the lens 1.

  The lens 1 is molded by the same process as injection molding for producing a general resin product, but requires higher dimensional accuracy than a general resin product, and it is necessary to reduce the contamination of dust and the like as much as possible. There is. For this reason, a molding machine is installed in an air-conditioned clean room to accurately control the molding machine temperature. For example, it is necessary to maintain the cleanliness level at about class 10,000. Changes in dimensions and the like in resin molding are known to change slightly depending on molding pressure, injection speed, holding time, mold temperature, ambient temperature, and the like, and the dimensional accuracy of the molded lens 1 can be monitored. is necessary.

  When evaluating the accuracy of the molded lens, in the case of an aspheric lens, it is necessary to perform shape measurement using the above-mentioned AFM (for example, UA3P manufactured by Matsushita Electric). This measurement is a complicated operation performed for each molding lot or at a timing such as at the start, midway, or after completion of the molding lot. For the purpose of facilitating such measurement work, annular corner portions 3, 4a and 4b formed in the edge portion 6 are used. Since the annular corners 3, 4 a and 4 b are molded at the same time as the lens effective portion 5, the edge portion 6 and the inlay portion 8, there are various factors which are considered to reduce the accuracy in forming the lens 1 (lens effective portion 5). This is reflected in the annular corners 3, 4 a and 4 b formed in the edge portion 6. Therefore, by observing the annular corners 3, 4 a and 4 b formed on the edge portion 6, for example, the eccentricity (a surface-specific eccentricity) for each aspheric surface that degrades the resolution of the lens 1 (lens effective portion 5) is evaluated. can do.

  The shape of the lens 1 according to this embodiment will be described. In FIG. 1B, the left lens surface forming the lens effective portion 5 is denoted as R1 surface, and the right lens surface is denoted as R2 surface. In one embodiment, the diameter of the R1 surface with respect to the optical axis 2 is Φ1.5 mm, and the diameter of the R2 surface is Φ1.4 mm. The diameters of the annular corners 3, 4a, and 4b are 2.50 mm, Φ2.51 mm, and Φ2.49, respectively. The outer diameter of the edge portion 6 is Φ4.2 mm, and the thickness is about 0.8 mm.

  Next, the annular corner portions 3, 4a and 4b formed in the edge portion 6 will be described in detail with reference to FIG. 2A is a diagram conceptually showing a partial cross section of a mold and a lens when the lens shown in FIG. 1 is injection-molded. FIG. 2B is an enlarged view of a portion A in FIG. The mold is made of tool steel and attached to the die set of the injection molding machine. In a lens mold, a block called an insert portion is separately processed and incorporated into a base. The insert part is produced by subjecting super steel or tool steel to rough shape processing, and then plating the surface with high hardness such as Ni. This plated portion is further precision processed using a precision lathe or the like.

  2A and 2B, PL indicates a parting line (divided surface) of the mold. The left mold 11 has a concave surface for forming the R1 surface of the lens effective portion 5 and an annular convex portion 11a corresponding to the annular concave portion 4 (corner portions 4a and 4b) formed in the edge portion 6. Has been. The right mold 12 is formed with a concave surface for forming the R2 surface of the lens effective portion 5 and a stepped depression for forming the edge portion 6 and the inlay portion 8. The space surrounded by the left mold 11 and the right mold 12 is filled with a resin injected from a gate (not shown) to perform molding.

  FIG. 2B illustrates an enlarged cross-sectional shape of the annular convex portion 11a. That is, the annular convex portion 11a protruding rightward from the plane corresponding to the parting line of the left mold 11 has a substantially rectangular cross section. In one embodiment, the substantially rectangular cross section has a long side of 10 μm (half the difference between the diameter Φ2.51 mm of the corner 4a and the diameter Φ2.49 mm of the corner 4b) and a height of about 8 μm. . The right-angle shape of the front end surface of the convex portion 11 a provided on the mold 11 is transferred and formed as a concave portion 4 having right-angle corner portions 4 a and 4 b on the edge portion 6 of the lens 1. Similarly, the corner portion 3 formed on the other surface of the edge portion 6 by the mold 12 is also formed at a right angle. That is, it is important that the corners 3, 4 a, and 4 b formed on both surfaces of the edge portion 6 of the lens 1 are formed as right-angled edges having a cross-sectional shape and almost no R (roundness).

  In addition, when a lens is shape | molded with glass, ball-shaped or disk-shaped material is put into a metal mold | die, it is softened by high temperature heating, and a predetermined shape is transcribe | transferred. Although the process and mold structure are different, the basic concept is the same as in the case of resin molding.

  FIG. 3 is a diagram corresponding to FIG. 2B when it is assumed that an annular convex portion is formed instead of the annular concave portion in the edge portion of the lens. The basic function of the annular recess 4 is to facilitate checking of the dimensional accuracy of the molded lens 1 as described above. In view of this function, it is considered that an annular convex portion may be formed on the edge portion 6 of the lens 1 instead of the annular concave portion 4.

  However, as shown in FIG. 3, when the annular convex portion 7 is formed on the edge portion 6, it is difficult to form a right-angle edge on the tip surface of the annular convex portion 7. In order to form a right-angled edge on the tip surface of the annular convex portion 7, it is necessary to form a concave portion 11b having a right-angled edge with almost no R on the bottom surface in the corresponding mold 11, but this is difficult. This is because the tip shape of the cutting tool used for processing the mold becomes an R shape (curved surface shape) having a certain size as shown in FIG.

  FIG. 4 is a perspective view illustrating the tip shape of a cutting tool for processing a mold. The cutting tool 14 is a diamond tool having a diamond attached to the tip 14a. In one example, the tip R (curvature radius) of the cutting tool 14 is about 2.3 μm. Therefore, as shown in FIG. 3, the bottom edge of the concave portion 11b formed in the mold 11 has an R shape of about 2.3 μm, and this shape is transferred to the tip surface of the annular convex portion 7 of the edge portion 6 to which the shape is transferred. The edge also has an R shape of about 2.3 μm. When the dimensional accuracy of the lens 1 is measured using such an annular convex portion 7 having a rounded and blunt edge, it is difficult to increase the measurement accuracy.

  On the other hand, in the lens 1 of the present embodiment, the edge shape of the tip surface of the annular convex portion 11a formed in the mold 11 in order to form the annular concave portion 4 in the edge portion 6 is a right-angle shape without R. can do. That is, even if the tip 14a as shown in FIG. 4 uses an R-shaped cutting tool, as shown by the arrow lines Y and Z in FIG. 2 (b), an annular convex portion from the outer peripheral side and the inner peripheral side of the mold. By processing so that the side surface of 11a is scraped up, the edge shape of the front end surface of the annular convex portion 11a can be made into a right-angle shape without R. As a result, the annular corners 4a and 4b (concave part 4) formed in the edge part 6 of the lens 1 can be formed as a right-angled edge with almost no R. For the same reason, the annular corner portion 3 formed by the inner peripheral wall 8a of the spigot portion 8 and the edge portion 6 can also be formed to have a right-angled edge without R. This makes it possible to accurately measure the dimensional accuracy of the lens 1 using the annular corners 3, 4a, and 4b.

  Next, a method of measuring the surface-specific eccentricity of the lens 1 by the annular corners 3, 4 a and 4 b formed on the edge portion 6 of the lens 1 will be described. When the lens 1 is set on a microscope or the like and irradiated with parallel light in the direction of the optical axis 2 of the lens 1, as shown in FIG. 1A, annular corners 3, 4 a provided on the edge portion 6, and Three rings corresponding to 4b are observed. As described above, since the annular corners 3, 4a, and 4b are all formed to be right-angled edges with almost no R, these three rings are observed as thin lines with a clear outline. . Moreover, since both surfaces of the edge part 6 are parallel and smooth planes, there is little refraction and scattering of incident parallel light. Therefore, it is possible to accurately observe the three rings corresponding to the annular corners 3, 4a and 4b.

  Also, since the depth of field of the microscope is shallow, in order to observe the three rings corresponding to the annular corners 3, 4a and 4b at the same time, two images are taken at different positions in the optical axis direction. A process for synthesizing both images is necessary. As a microscope system capable of such processing, for example, a metal microscope high-depth image analysis system DF-2 manufactured by Olympus is known. Alternatively, a confocal microscope or the like can be used. As a simpler observation method, observation using a projector or the like is also possible. In addition, it is desirable to use light having an appropriate wavelength as light transmitted through the lens 1 in accordance with the visibility of the three rings corresponding to the annular corners 3, 4 a and 4 b.

  In the case of the lens 1 of the present embodiment, when three rings corresponding to the annular corners 3, 4 a and 4 b formed on the edge portion 6 are observed with a microscope, 3 3 as shown in FIG. Observed as concentric circles close to the book. FIG. 5 is an enlarged view of a portion B in FIG. Since the annular corners 4a and 4b (concave part 4) formed on one surface of the edge portion 6 are simultaneously molded by the same mold 11 as the R1 surface of the lens, there is a close relationship with the dimensional accuracy of the R1 surface. On the other hand, since the annular corner 3 is simultaneously molded by the same mold 12 as the R2 surface of the lens, there is a close relationship with the dimensional accuracy of the R2 surface. Therefore, when the three rings corresponding to the annular corners 3, 4a and 4b are observed as concentric circles at regular intervals in the radial direction, the dimensional accuracy of the respective lens surfaces R1 and R2 is good. It can be estimated that there is.

  As described above, in the lens 1 of the present embodiment, if the annular ring formed by the corner 3 is sandwiched between the corners 4a and 4b formed on both sides of the recess 4, the optical axis decentering within a plane is within 5 μm. It can be estimated that. That is, the diameters of the annular corners 3, 4a and 4b are given a difference of 10 μm. If the center of the R1 surface and the center of the R2 surface are decentered by 5 μm in opposite directions, the two circumferences Part of is observed overlapping. If the eccentricity is 5 μm, it can be reliably detected. In the lens 1 of the present embodiment, the allowable eccentricity is designed to be 10 μm, and when there is an eccentricity exceeding the allowable eccentricity, it can be sufficiently detected by observing the circular rings corresponding to the corners 3, 4 a and 4 b.

  If even greater eccentricity occurs, two overlapping portions will be observed in these rings. If a larger amount of eccentricity is acceptable in the design of the lens, the difference in diameter between the annular corners 3, 4a and 4b may be set to a larger value. That is, if the difference between these diameters is set to a value twice the allowable eccentricity, the evaluation of the eccentricity between the two lens surfaces R1 and R2 can be accurately performed. Conversely, when the allowable eccentricity is small, the difference in diameter between the annular corners 3, 4a and 4b may be set to a small value.

  FIG. 6 is a view for explaining the visibility of the annular corner formed in the edge portion of the lens according to the first embodiment of the present invention. 6A and 6B show a part of the ring corresponding to the three annular corners 3, 4 a and 4 b formed on the edge 6 of the lens 1 of the present embodiment as a straight line. It is shown schematically. In the state of FIG. 6A, the annular corner 3 on the other surface is located just between the annular corners 4 a and 4 b on one surface of the edge portion 6. This state indicates that there is no eccentricity between the two lens surfaces R1 and R2. In the state of FIG. 6B, it can be easily seen that the corner 3 is slightly shifted to the left (inward) from the middle of the corners 4a and 4b. This state indicates that there is an eccentricity between the two lens surfaces R1 and R2.

  For comparison, FIGS. 6C and 6D show a case where the presence / absence of eccentricity is checked only with the circular rings corresponding to the two annular corners 3 and 4a. That is, this corresponds to a state in which only one of the corners 4a and 4b on one side of the edge portion 6 is left except for the other one 4b. FIG. 6C corresponds to FIG. 6A, and FIG. 6D corresponds to FIG. 6B. In this case, the presence or absence of eccentricity is checked based on the size of the space between the rings corresponding to the two corners 4 and 3b. Compared with such a check method, a check method using a ring corresponding to three annular corners 3, 4a and 4b as in the present embodiment shown in FIGS. 6 (a) and 6 (b). It is clear that the visibility is better and a slight eccentricity can be visually recognized.

  Further, the dimensional accuracy of the lens surfaces R1 and R2 can be estimated by measuring the roundness of the circular rings corresponding to the three corners 3, 4a and 4b. In this case, a simple evaluation can be performed by preparing a chart depicting a perfect circle in a projector or the like in advance and observing the difference between the projected images of the corners 3, 4 a and 4 b and the chart. If the range of allowable roundness is described on the chart, the evaluation becomes easier. It is preferable to evaluate in advance the correlation between the roundness of the ring corresponding to the corners 3, 4 a and 4 b and the optical characteristics of the lens. When the lens 1 of the present embodiment was produced under variously changed molding conditions and the optical characteristics thereof were evaluated, if the above eccentricity was within the allowable eccentricity range, the roundness could not be evaluated. However, it has been confirmed from the experimental design that other shape accuracy can be sufficiently achieved. Therefore, if evaluation of the eccentricity of the ring corresponding to the corners 3, 4 a and 4 b is performed, the dimensional accuracy related to the optical characteristics required for the lens 1 can be ensured.

(Embodiment 2)
Next, a lens according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a diagram schematically showing a lens according to the second embodiment of the present invention. FIG. 7A is a plan view of the lens viewed from the optical axis direction, and FIG. 7B is a cross-sectional view of the lens of FIG. 7A taken along line XX. FIG. 8 is an enlarged view of a portion C in FIG. FIG. 9 is a view for explaining the visibility of the annular corner formed in the lens of the second embodiment of the present invention.

  The basic shape, material, molding method and the like of the lens 1 of the present embodiment are the same as those of the lens of the first embodiment. The lens 1 of this embodiment is different from the lens of the first embodiment in that the inlay portion 8 is erected in the axial direction from the inner side slightly from the outer peripheral end of the edge portion 6, and as a result, the inner portion of the base portion of the inlay portion 8. The corners are formed not only on the circumferential side but also on the outer circumferential side. That is, as shown in FIG. 7, the outer corner portion 3 a and the inner corner portion 3 b are formed on the lens surface R <b> 2 side surface of the edge portion 6.

  The width of the concave portion 4 formed on the surface of the edge portion 6 on the lens surface R1 side is twice the width of the spigot portion 8. The outer peripheral corner 4a formed on the bottom surface and the outer peripheral side surface of the recess 4 and the outer peripheral corner 3a of the base of the inlay portion 8 have the same diameter, and are formed so as to overlap in plan view if there is no eccentricity. ing. Further, the corner portion 3b on the inner peripheral side of the spigot portion 8 is disposed between the corner portion 4a on the outer peripheral side of the recess 4 and the inner peripheral side 4b.

  Accordingly, when the lens 1 is set on a microscope or the like and irradiated with parallel light in the direction of the optical axis 2 as in the first embodiment, four circles corresponding to the four corners 3a, 3b, 4a, and 4b. A ring is observed, but if there is no eccentricity as described above, the two rings corresponding to the corners 3a and 4a overlap and appear as one. FIG. 7A shows this state. FIG. 8 is an enlarged view of a portion C in FIG.

  That is, in the lens 1 of the present embodiment, whether or not the pitches of the annular rings corresponding to the three corners 3a (4a), 3b, and 4b are equal as in the lens of the first embodiment (one in the circumferential direction). In addition to checking the presence or absence of decentration between the lens surfaces R1 and R2, the circular rings corresponding to the two annular rings 3a and 4a on the outer peripheral side overlap to form one. The presence or absence of decentration between the lens surfaces R1 and R2 can also be checked by observing whether or not it is visible.

  Next, with reference to FIG. 9, the visibility of the annular corner formed in the edge portion of the lens according to the present embodiment will be described. In FIG. 9, a part of the ring corresponding to the two annular corners 3a and 4a on the outer peripheral side is schematically shown as a straight line. A state in which the annular lines corresponding to the two annular corners 3a and 4a are completely overlapped (a), a state of being slightly overlapped (b), a state of being slightly separated (c), and A state (d) separated by an interval of about the line width is shown. Thus, if the overlap or deviation of the circular lines corresponding to the two annular corners 3a and 4a is evaluated, the presence or absence of the eccentricity between the lens surfaces R1 and R2 can be evaluated. That is, the magnitude of eccentricity can be evaluated in more detail than in the first embodiment.

  The first and second embodiments as described above can be combined or modified as appropriate. FIG. 10 shows a cross-sectional shape of a lens according to a modification of the embodiment of the present invention. In the lenses of FIGS. 10A and 10B, the shape of the lens effective portion 5 is a convex / concave lens, and in the lenses of FIGS. 10C and 10D, the shape of the lens effective portion 5 is as shown in FIGS. Like the biconvex lens. The shape of the lens effective portion 5 is not directly related to the present invention, and may be an arbitrary shape.

  In the lens of FIG. 10A, an annular recess 4 is formed on the inner peripheral side of the spigot portion 8 that protrudes in the axial direction from one surface of the edge portion, and the annular recess 4 is also formed on the other surface. Is formed. Therefore, an annular line corresponding to a total of four corners is obtained. As for the positional relationship of these four lines, as in the above-described embodiment, the two lines formed on one surface are sandwiched by one formed on the other surface, or the lines on both sides are arranged. Can be arranged to overlap.

  The lens in FIG. 10B is a lens in which a step is provided on the tip surface of the inlay portion 8 in the lens in FIG. In the lens of FIG. 10C, an annular recess 4 is formed on the outer peripheral side of the spigot portion 8 formed on one surface of the edge portion, and a corner portion 3 is formed on the inner peripheral side. A small inlay portion 8 ′ is formed on the surface, an annular recess 4 is formed on the inner peripheral side, and an annular corner 3 is formed on the outer peripheral side.

  The lens effective portion 5 of the lens in FIG. 10C is a biconvex lens, but the tip surface of the inlay portion 8 formed in the edge portion protrudes in the optical axis direction from the lens effective portion 5. In handling such as movement or mounting of a lens, for example, when a lens is placed on a flat table, if the inlay portion 8 is placed downward, the tip surface of the inlay portion 8 contacts the flat table, and the lens effective portion 5 Since it does not contact, damage to the lens surface is prevented. The same applies when the lens is accommodated in a tray or the like.

  Further, when the lens is attached to the lens barrel and the edge portion is bonded and fixed, the inlay portions (projections) 8 and 8 ′ function as a bank that prevents the adhesive from entering the lens effective portion. Further, the annular recess 4 formed in the vicinity of the spigot portions (protrusions) 8 and 8 'functions as a reservoir for extra adhesive. The annular recess 4 formed on the outer peripheral side of the inlay part (projection part) 8, 8 ′ functions as an original adhesive reservoir, and the annular recess 4 formed on the inner periphery side is the inlay part (projection part) 8. , 8 ′ functions as a moat that prevents the adhesive from entering the lens effective portion 5 from entering. This stabilizes the quality of the lens / lens barrel assembly and facilitates management of the amount of adhesive applied.

  The lens shown in FIG. 10D is a modification of the lens shown in FIG. The height (dimension in the optical axis direction) of the inlay portion (projection portion) 8 formed on one surface of the edge portion is reduced, and the inner periphery side of the inlay portion (projection portion) 8 ′ formed on the other surface is reduced. The recess 4 is omitted.

  The above-described embodiments and modifications can be appropriately selected according to the required accuracy of the lens, measurement restrictions, molding restrictions, and the like, or may be implemented in combination.

(Embodiment 3)
Next, as a third embodiment of the present invention, an example of an imaging device using the lenses of the above-described embodiments and modifications will be described. FIG. 11 is a perspective view of an imaging apparatus using the lens of the present invention. The imaging device 20 is a mobile phone camera module. 12 is a cross-sectional view of the lens barrel portion of the imaging apparatus in FIG. 11 as viewed from the side.

  The image pickup apparatus 20 includes a lens unit 1U in which two lenses 1A and 1B are combined, a lens barrel 31 that holds the lens unit 1U, an optical filter 24, a semiconductor image pickup device 25, and a three-dimensional board 22 that holds them, and is connected to the outside And a flexible printed circuit board (FPC) 30 that transmits and receives signals to and from the computer. The three-dimensional substrate 22 also serves as a holding member that holds the lens barrel 31, the semiconductor imaging device 25, and the optical filter 24. The lens unit 1U is fixed so that the outer peripheral surface and the upper surface of the upper lens 1A constituting the lens unit 1U are fitted into the inner peripheral surface and the ceiling surface of the lens barrel 31. An opening 27 that forms a stop is formed at the center of the ceiling surface of the lens barrel 31.

  The semiconductor imaging device 25 disposed below the lens unit 1U is, for example, a 1/4 inch CCD having about 1.3 million pixels and a pixel size of about 2.8 μm. The semiconductor imaging element 25 is electrically connected to a conductive pattern formed on the surface of the three-dimensional substrate 22 by SBB (Stud Bump Bond). The conductive pattern of the three-dimensional board 22 is drawn out from the three-dimensional board 22 and connected to the conductive pattern 30a of the FPC 30 by soldering. The optical filter 24 disposed on the semiconductor imaging device 25 has a function of suppressing transmission of light outside the visible light region. Light from the subject is collected by the lens 1, passes through the optical filter 24, and enters the semiconductor image sensor 25. The semiconductor imaging device 25 outputs an electrical signal corresponding to the incident light, and the electrical signal is extracted to the outside through the conductive pattern 30a.

  Of the two lenses 1A and 1B constituting the lens unit 1U, the upper lens 1A is similar to the lens shown in FIG. The lower lens 1B is similar to the lens shown in FIG. The two lenses 1A and 1B are combined so that the inner peripheral wall of the inlay portion 8A of the upper lens 1A is fitted to the outer peripheral wall of the inlay portion 8B of the lower lens 1B to constitute a lens unit 1U. .

  In this way, the two lenses 1A and 1B are directly coupled, and the axial and radial positioning is performed by fitting the spigot portions 8A and 8B. By doing so, the optical axes of the two lenses are aligned with higher precision than when the two lenses are individually fixed to the lens barrel. In addition, with respect to the eccentricity of the lens surface of each lens, it is possible to easily ensure the accuracy of 5 μm or less as described above, so that stable quality and reduction in management man-hours are realized. As a result, it is possible to prevent a decrease in resolution due to curvature of field at the periphery of the light receiving surface of the semiconductor image sensor 25. The two lenses 1 </ b> A and 1 </ b> B are fixed by filling the adhesive 15 between these outer peripheral wall surfaces and the inner peripheral wall surface of the lens barrel 31 and curing them. At this time, as described above, the annular protrusion 8B 'of the lens 1B functions as a bank that prevents excessive adhesive 15 from entering the inside (lens effective portion). This stabilizes the quality of the lens / lens barrel assembly and facilitates management of the amount of adhesive applied.

  If the imaging device 20 as described above is used in a mobile phone with a camera function, good image quality can be obtained from the center to the periphery of the captured image, which can contribute to an increase in added value of the mobile phone.

1A and 1B are a plan view and a cross-sectional view schematically showing a lens according to a first embodiment of the present invention. FIG. 2A is a diagram conceptually showing a partial cross section of a mold and a lens when the lens shown in FIG. 1 is injection-molded, and FIG. FIG. 3 is a view corresponding to FIG. 2B when it is assumed that an annular convex portion is formed instead of an annular concave portion in the edge portion of the lens. It is a perspective view which illustrates the front-end | tip part shape of the blade tool which processes a metal mold | die. It is an enlarged view of the B section in Drawing 1 (a). It is a figure for demonstrating the visibility of the cyclic | annular corner | angular part formed in the edge part of the lens which concerns on the 1st Embodiment of this invention. It is the top view (a) and sectional view (b) which show typically the lens concerning a 2nd embodiment of the present invention. It is an enlarged view of the C section in FIG. It is a figure for demonstrating the visibility of the cyclic | annular corner | angular part formed in the lens of the 2nd Embodiment of this invention. It is a figure which shows the cross-sectional shape of the lens which concerns on the modification of embodiment of this invention. It is a perspective view of an imaging device using the lens of the present invention. It is sectional drawing which looked at the lens-barrel part of the imaging device of FIG. 11 from the side surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A, 1B Lens 2 Optical axis 3, 3a, 3b, 4a, 4b Annular corner | angular part 4 Annular and belt-shaped recessed part 5 Lens effective part 6 Edge part 8, 8A, 8B Inner part 20 Imaging device 22 Three-dimensional board 24 Optical Filter 25 Semiconductor image sensor 27 Aperture opening 30 Printed circuit board (FPC)
31 Lens tube

Claims (7)

  A lens effective portion that forms a lens surface around the optical axis, a donut-shaped edge portion in plan view that extends around the outer periphery of the lens effective portion, and the optical axis that is formed on both surfaces of the edge portion. A lens having an annular corner portion in plan view, wherein the lens effective portion, the edge portion, and the corner portion are integrally and simultaneously molded. The lens according to claim 1, wherein the annular corner portion is formed at a position having substantially the same radius around the optical axis on both surfaces of the edge portion. 3. The lens according to claim 1, wherein an annular and band-shaped recess is formed on at least one surface of the edge portion, and an angle formed by a bottom surface and a side surface of the recess corresponds to the corner portion. 4. The ring-shaped and band-shaped protrusions in plan view are formed on at least one surface of the edge part, and an angle formed by a side surface of the protrusion part and the surface of the edge part corresponds to the corner part. Lens. The lens of Claim 4. The front end surface of the said projection part protrudes in the said optical axis direction from the said lens surface. 6. The lens according to claim 4, wherein an annular and belt-like concave portion in plan view is formed in the vicinity of the annular and belt-like protrusion in plan view. An imaging apparatus comprising: the lens according to claim 1; and a semiconductor imaging element that outputs an electric signal of an image formed by receiving light condensed by the lens.

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