JP2007163798A - Lens and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens capable of easily and accurately evaluating dimensional accuracy of a lens surface and facilitating accuracy control of the lens. <P>SOLUTION: The lens 1 comprises: a lens effective part 5 which forms the lens surface around an optical axis 2; and an edge part 6 having a doughnut shape as a plain view which is extendedly disposed on the outer circumference of the lens effective part 5, wherein the edge part 6 is molded simultaneously with the lens effective part 5 and annular grooves 3, 4 are formed continuously or intermittently along circles around the optical axis 2. The two annular grooves 3, 4 have diameters slightly different from each other and are seen proximate to each other in a plain view. Otherwise, the two annular grooves have diameters equal to each other, are intermittently formed along the circular direction and form substantially continuous circumferences while being interpolated to each other in a plain 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 aspherical, optical property data is measured using an AFM (Atomic Force Microscope) or the like, and the aspherical design data is molded. Measure 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 includes a lens effective portion that forms a lens surface around the optical axis, and a donut-shaped edge portion that is extended in the outer periphery thereof, and the edge portion is simultaneously with the lens effective portion. The annular groove is formed on both surfaces of the edge portion continuously or intermittently along a circle centered on the optical axis.

  In the lens of the present invention, when parallel light is irradiated to the edge portion, an annular line corresponding to the annular groove formed on both surfaces of the edge portion can be observed. Therefore, by evaluating the eccentricity of these annular lines, etc. 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, both sides of the edge portion are formed to be two parallel planes. According to this configuration, since the light transmitted through the edge portion is not refracted or tilted, it is possible to prevent the measurement accuracy from deteriorating. In addition, high reproducibility of measurement can be maintained even when parallel light is irradiated from either the front or back side of the lens. In addition, an allowable range can be created in advance in a master chart using a universal projector, etc., and it can be checked whether the projected annular groove is within the allowable range to check and manage the accuracy of the lens. Is possible.

  The annular groove preferably has a V-shaped cross-section with a sharp tip. According to this configuration, since the annular line corresponding to the annular groove is observed as a clear line with a sufficiently thin outline, the accuracy of the lens can be measured more accurately. In addition, since the visibility during measurement is improved, the workability of precision work is improved.

  Moreover, it is preferable that the diameter of the two annular grooves formed on both surfaces of the edge portion is different, and the two annular grooves appear close to each other in plan view. According to this configuration, since two annular lines corresponding to both lens surfaces are observed in a state of being close to each other, the visibility of the presence or absence of deviation between them, that is, the presence or absence of eccentricity is improved. Further, if the degree (interval) between the two annular grooves in a plan view is set to be equal to the accuracy required for the lens, whether or not the two annular grooves overlap each other in a part in the circumferential direction. By checking this, the eccentricity (dimensional accuracy) of the two lens surfaces can be easily determined. That is, the presence or absence of eccentricity can be visually determined without measuring the dimensions.

  Alternatively, the two annular grooves formed on both surfaces of the edge portion have the same diameter and are intermittently formed along the circumferential direction, and the two intermittent annular grooves complement each other in plan view. They are preferably arranged so as to form a substantially continuous circumference. According to this configuration, the presence or absence of decentering of both lens surfaces can be visually checked by checking whether or not the substantially continuous circumference formed by the two intermittent annular grooves complementing each other is a smooth line. Can be easily determined. In addition, it is possible to easily determine at which position in the circumferential direction the eccentricity occurs (and its degree).

  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.

(First embodiment)
FIG. 1 is a diagram schematically showing a lens according to the first embodiment of the present invention. FIG. 1A is a plan view of the lens seen from the optical axis direction, and FIG. 1B is a cross-sectional view of the lens of FIG. 1A taken along line XX.

  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 and a donut-shaped edge portion 6 that is extended in the outer periphery of the lens 1. Have. The edge portion 6 is integrally and simultaneously molded with the lens effective portion 5. 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.

  One or a plurality of lenses 1 are incorporated in a lens barrel portion of an imaging device described later, and a predetermined imaging optical system is formed. 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 of the lens 1 has a function for positioning and fixing the lens 1 with respect to the lens barrel portion. Both sides (surfaces perpendicular to the optical axis) of the edge portion 6 are formed to be two parallel and smooth planes.

  Grooves 3 and 4 having a V-shaped cross section (hereinafter referred to as annular grooves) 3 and 4 are formed on both sides of the edge portion 6 along a circle centered on the optical axis 2. These annular grooves 3 and 4 are formed simultaneously when the lens 1 (the lens effective portion 5 and the edge portion 6) is resin-molded. In the lens 1 of the present embodiment, the radius of the annular groove 4 formed on one surface of the edge portion 6 is slightly smaller than the radius of the annular groove 3 formed on the other surface. Thereby, as shown to Fig.1 (a), the two annular grooves 3 and 4 appear near each other by planar view. These annular grooves 3 and 4 have a function of making it possible to easily check the eccentricity of the lens surface of the lens 1. 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 a measurement operation, two annular grooves 3 and 4 are formed on both sides of the edge portion 6. Since the lens effective portion 5 and the edge portion 6 of the lens 1 are molded at the same time, various factors that are considered to reduce the accuracy in molding the lens 1 (lens effective portion 5) are also reflected in the edge portion 6. Therefore, by observing the annular grooves 3 and 4 formed in 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) can be evaluated. .

  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 diameter of the annular groove 3 is Φ2.51 mm, and the diameter of the annular groove 4 is Φ2.50 mm. The outer diameter of the edge portion 6 is Φ4.2 mm, and the thickness is about 0.8 mm.

  Next, the annular grooves 3 and 4 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 is formed with a concave surface for forming the R1 surface of the lens effective portion 5. The right mold 12 has a concave surface for molding the R2 surface of the lens effective portion 5, and a stepped depression for molding the edge portion 6 is formed around the concave surface. 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. In addition, annular projections 11 a and 12 a corresponding to the annular grooves 3 and 4 are formed on the planar portions of the left and right molds 11 and 12 corresponding to the two parallel planes of the edge portion 6.

  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 triangular cross section with a sharp tip. In one embodiment, the base of the substantially triangular cross section (base width) is about 30 μm and the height is about 8 μm. In FIG. 2B, the height of the annular protrusion 11a is exaggerated. The shape of the annular convex portion 11a having a substantially triangular cross section with a sharp tip is transferred to the edge portion 6 of the lens 1 to form an annular groove 3 with a sharp tip at a V-shaped cross section. 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 view corresponding to FIG. 2B when it is assumed that an annular convex portion is formed in the edge portion of the lens instead of the annular groove. The basic function of the annular grooves 3 and 4 is to facilitate checking the dimensional accuracy of the molded lens 1 as described above. In view of this function, it is considered that annular convex portions may be formed on both surfaces of the edge portion 6 of the lens 1 instead of the annular grooves 3 and 4.

  However, as shown in FIG. 3, when the annular convex portion 7 is formed on the edge portion 6, the tip of the annular convex portion 7 cannot be sharpened. In order to make the tip of the annular convex portion 7 sharp, it is necessary to form a V-shaped groove in the corresponding mold 11, but it is difficult to process the tip (bottom) into a sharp shape. 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 (radius of curvature) of the cutting tool 14 is about 2.3 μm. Therefore, as shown in FIG. 3, the tip of the V-shaped groove 11b formed in the mold 11 has an R shape of about 2.3 μm. The tip also has an R shape of about 2.3 μm. When measuring the dimensional accuracy of the lens 1 using such an annular convex portion 7 having a rounded and blunt shape, it is difficult to increase the measurement accuracy.

On the other hand, in the lens 1 of the present embodiment, the tips of the annular convex portions 11a and 12a formed on the molds 11 and 12 for forming the annular grooves 3 and 4 on the edge portion 6 are sufficiently sharpened. The shape can be changed. 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. 2B, the annular convex portion 11a from the outer peripheral side and the inner peripheral side of the mold. And the tip of annular convex part 11a and 12a can be made into the pointed shape by processing so that the mountain surface of 12a may be shaved up. As a result, the cross-sectional shape of the annular grooves 3 and 4 formed in the edge portion 6 of the molded lens 1 can be made V-shaped with a sharp tip, and the lens 1 formed by the annular grooves 3 and 4 can be formed. It becomes possible to measure the dimensional accuracy with high accuracy.
In manufacturing the mold, the portion corresponding to the annular grooves 3 and 4 is processed simultaneously with the portion corresponding to the effective portion 5 of the lens 1 so that the dimensional accuracy between the two is increased.

  Next, a method for measuring the surface-specific eccentricity of the lens 1 using the annular grooves 3 and 4 will be described. First, the lens 1 is set on a microscope or the like, and parallel light is irradiated in the direction of the optical axis 2 of the lens 1. An annular line is observed by the annular grooves 3 and 4 provided in the edge portion 6. As described above, since the annular grooves 3 and 4 have a V-shaped cross-section with a sharp tip, the annular line is observed as a thin line 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, the annular line corresponding to the annular grooves 3 and 4 can be accurately observed.

  Also, since the depth of field of the microscope is shallow, in order to observe two annular lines corresponding to the annular grooves 3 and 4 simultaneously, two images are taken at different positions in the optical axis direction. The process which synthesize | combines is required. 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. Further, it is desirable to use light having an appropriate wavelength as light transmitted through the lens 1 in accordance with the visibility of the annular grooves 3 and 4.

  In the case of the lens 1 of the present embodiment, when the annular grooves 3 and 4 formed on both surfaces of the edge portion 6 are observed with a microscope, they are observed as two adjacent concentric circles as shown in FIG. Since the annular groove 3 formed on one surface of the edge portion 6 is 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. Similarly, since the annular groove 4 formed on the other surface of the edge portion 6 is simultaneously molded by the same mold 11 as the R2 surface of the lens, there is a close relationship with the dimensional accuracy of the R2 surface. Therefore, when two circles corresponding to these two annular grooves 3 and 4 are observed like concentric circles at a constant interval in the circumferential direction, it is estimated that the dimensional accuracy of each lens surface R1 and R2 is good. To do.

  As described above, in the lens 1 of the present embodiment, the diameters of the annular grooves 3 and 4 are Φ2.50 mm and Φ2.51 mm, respectively, and a difference of 10 μm is given to both. If the center of the R1 plane is decentered by 2 μm and the center of the R2 plane is shifted by 3 μm in the reverse direction, the two circles corresponding to the annular grooves 3 and 4 are observed to overlap. 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. If there is an eccentricity exceeding this allowable eccentricity, it can be sufficiently detected by observing the annular grooves 3 and 4.

  When a larger eccentricity occurs, two overlapping portions are observed in the two circles corresponding to the annular grooves 3 and 4. If a larger amount of eccentricity is acceptable in terms of lens design, the difference in diameter between the two annular grooves 3 and 4 may be set to a large value. For example, if the difference between the diameters of the two annular grooves 3 and 4 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, if the allowable eccentricity is small, the difference in diameter between the annular grooves 3 and 4 may be set to a small value.

  Further, by measuring the roundness of each of the annular grooves 3 and 4, the dimensional accuracy of the respective lens surfaces R1 and R2 can be estimated. 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 image of the annular grooves 3 and 4 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 circularity of the annular grooves 3 and 4 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 the eccentricity of the annular grooves 3 and 4 is evaluated, the dimensional accuracy related to the optical characteristics required for the lens 1 can be ensured.

(Second Embodiment)
Next, a lens according to a second embodiment of the present invention will be described with reference to FIGS. Fig.5 (a) is the top view which looked at the lens which concerns on the 2nd Embodiment of this invention from the optical axis direction. FIG. 5B is a cross-sectional view of the lens of FIG. 5A taken along line XX. FIG. 6 is an enlarged view of a portion B in FIG.

  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 the present embodiment is different from the lens of the first embodiment in that the annular grooves 3 and 4 formed on both surfaces of the edge portion 6 have the same diameter and are intermittent along the circumferential direction. The two annular grooves 3 and 4 that are intermittently formed are arranged so as to complement each other in a plan view to form a substantially continuous circumference.

  As can be seen from the enlarged view of FIG. 6, the annular grooves 3 and 4 are both formed intermittently along the circumferential direction as indicated by the broken line, and are located on the same circumference. The intermittent annular grooves 3 and 4 complement each other to form a substantially continuous circumference. This state is a case where there is no eccentricity between the lens surfaces R1 and R2. If there is an eccentricity, the annular groove 3 and the annular groove 4 are displaced from each other, so that the circumference is not clean in plan view. Accordingly, when the annular grooves 3 and 4 are observed in a plan view, the presence or absence of the eccentricity between the lens surfaces R1 and R2 and the size thereof can be readily known.

  It is not always necessary that the circumference formed by the annular grooves 3 and 4 in a plan view is completely continuous without any eccentricity. You may form so that a clearance gap may be made between the segment of the annular groove 3, and the segment of the annular groove 4. FIG. On the contrary, you may form so that the segment of the annular groove 3 and the segment of the annular groove 4 may overlap partially. Further, the line type may be changed so that the lengths of the segments are different or one is a dotted line and the other is a one-dot chain line so that the annular groove 3 and the annular groove 4 can be easily identified. In the example of FIG. 6, the annular grooves 3 and 4 are both broken lines, but are formed so that the segment length of the annular groove 3 is longer than the segment length of the annular groove 4.

  As one method of dividing the annular grooves 3 and 4 into circumferential segments as indicated by broken lines, the sharp shape of the mold corresponding to the tips of the annular grooves 3 and 4 is intermittently caused in the circumferential direction by etching or electric discharge machining. As the R shape, there is a method of blurring (making it invisible) a line. As another method, the annular convex portions of the mold corresponding to the annular grooves 3 and 4 may be intermittently removed in the circumferential direction.

  In FIG. 6, the annular grooves 3 and 4 are cleanly connected to form a substantially continuous circumference. However, if there is a line width or more shift between the two, the lens surfaces R1 and R2 are between. It can be easily estimated that there is eccentricity. As described above, in the lens of the first embodiment, it can be visually recognized if there is an eccentricity of about half or more of the difference between the diameter of the annular groove 3 and the diameter of the annular groove 4, but the lens of this embodiment has a smaller eccentricity. It is possible to visually recognize. This is because it is easier to visually check whether or not the annular grooves 3 and 4 are cleanly connected to form one circumference, and high visual accuracy can be obtained. Further, when the roundness of the lens surfaces R1 and R2 is shifted in different directions, it is relatively easy to visually recognize at which position in the circumferential direction the roundness is shifted.

  In the state where the diameter of the annular groove 3 and the diameter of the annular groove 4 are slightly different as in the first embodiment, one or both of the annular grooves are intermittently formed along the circumferential direction as indicated by a broken line. Forming embodiments are also possible.

(Third embodiment)
Next, an example of an imaging apparatus using the lens of the first or second embodiment will be described as the third embodiment of the present invention. FIG. 7 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. FIG. 8 is a cross-sectional view of the imaging device of FIG. 7 as viewed from the side.

  The imaging device 20 includes a lens 1 having an optical axis 2, an optical filter 24, a semiconductor imaging device 25, a three-dimensional board 22 that holds them, and a flexible board that is connected to the three-dimensional board 22 and exchanges signals with the outside. And a printed circuit board (FPC) 30. The three-dimensional substrate 22 also serves as a holding member that holds the semiconductor imaging device 25 and the optical filter 24. The three-dimensional substrate 22 includes a cylindrical barrel portion 22a and a bottom portion 22b extending outward from one end side of the barrel portion 22a.

  The lens 1 is fitted and fixed to the inner peripheral surface of the lens barrel 22 a of the three-dimensional substrate 22. 8 is a concave-convex lens, a biconvex lens as illustrated in the first or second embodiment may be used, or a plano-convex lens may be used. Further, in the cross section shown in FIG. 8, only one lens is drawn, but in reality, a plurality of lenses are often mounted. For example, by combining two lenses, a pan-focus optical system capable of forming an object farther than a certain distance (for example, 30 cm) is configured. On the lens 1, a diaphragm 27 for fixing the lens 1 and obtaining a predetermined aperture is attached.

The semiconductor imaging device 25 disposed below the lens 1 is a 1/4 inch CCD having, for example, about 1.3 million pixels and a pixel size of about 2.8 μm. The semiconductor imaging device 25 is electrically connected to the conductive pattern 23 formed on the surface of the three-dimensional substrate 22 by SBB (Stud Bump Bond). The conductive pattern 23 is drawn out to the side surface of the bottom 22b of the three-dimensional board 22, and is connected to the conductive pattern 30a of the FPC 30 by soldering. The optical filter 24 disposed on the semiconductor image sensor 25 via the spacer 28 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 patterns 23 and 30a. According to the lens 1 of the present invention, as described above, it is possible to easily ensure the accuracy that the eccentricity is 5 μm or less, and it is possible to achieve stable quality and reduction in management man-hours. 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. Furthermore, if this imaging device 20 is used for a mobile phone with a camera function, good image quality can be obtained from the center to the periphery of the photographed 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 conceptual diagram showing a partial cross section of a mold and a lens when the lens shown in FIG. 1A is injection-molded, and FIG. It is a figure equivalent to FIG.2 (b) when it assumes that an annular convex part is formed in the edge part of a lens instead of an annular groove. 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 the top view (a) and sectional view (b) which show typically the lens concerning a 2nd embodiment of the present invention. It is the B section enlarged view of Drawing 5 (a). It is a perspective view of an imaging device using the lens of the present invention. It is sectional drawing which looked at the imaging device of FIG. 7 from the side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens 2 Optical axis 3, 4 Annular groove 5 Lens effective part 6 Edge part 20 Imaging device 22 Three-dimensional substrate 22a Lens barrel part 22b Bottom part 24 Optical filter 25 Semiconductor image pick-up element R1, R2 Lens surface

Claims (6)

  A lens effective portion that forms a lens surface with the optical axis as a center, and a donut-shaped edge portion in plan view extending on the outer periphery thereof, and the edge portion is formed simultaneously with the lens effective portion, and the edge portion An annular groove is formed continuously or intermittently along a circle centered on the optical axis on both surfaces of the lens. The lens according to claim 1, wherein both sides of the edge portion are formed to be two parallel planes. The lens according to claim 1, wherein the annular groove has a V-shaped cross section with a pointed tip. The lens according to claim 1, wherein the two annular grooves formed on both sides of the edge portion have different diameters, and the two annular grooves appear close to each other in plan view. The two annular grooves formed on both sides of the edge portion have the same diameter and are intermittently formed along the circumferential direction, and the two intermittent annular grooves complement each other in plan view. The lens according to claim 1, wherein the lens is disposed so as to form a substantially continuous circumference.   6. An imaging apparatus comprising: the lens according to claim 1; and a semiconductor imaging device that outputs an electric signal of an image formed by receiving light condensed by the lens.

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