JP2015165338A - imaging lens system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging lens system with high resolution in an embodiment suppressing enlargement in a size of the imaging lens system.SOLUTION: The imaging lens system comprises, in order from an object side, at least: a first lens group including a first lens convex on the object side; a second lens group including a second lens concave on an image side; a third lens group including a third meniscus lens concave on the object side; a fourth lens group including a fourth meniscus lens concave on the object side; and a fifth lens group including a fifth meniscus lens having an aspherical surface with an inflection point arranged on the object side. When a cross section is viewed in a plane surface including an optical axis, the fifth lens is an aspherical lens that has first and second inflection points at which an extension direction of a contour line of the fifth lens changes firstly on the object side and on an image-formation side, respectively toward an outer periphery from a center. When a focal length of the imaging lens system is f, a height of the first inflection point from the optical axis is i1 and a height of the second inflection point is i2, the imaging lens satisfies i1/f<0.20 and i2/f<0.26.

Description

  The present invention relates to an imaging lens system.

  With the progress of the increase in the number of pixels of an image sensor such as a CCD (Charge Coupled Device), a high resolving power is required for an imaging lens system disposed on the image sensor. In addition, with the progress of miniaturization and thinning of main devices (digital still cameras, mobile phones, etc.), there is a strong demand for miniaturization and thinning of imaging lens systems mounted on main devices.

  A high resolution can be realized by making the lens aspherical using a glass material having a high refractive index, increasing the number of lenses, and the like. However, when the number of lenses is simply increased, the imaging lens system becomes large, which is against the demand for miniaturization.

  Patent Document 1 discloses a small lens composed of first to third groups. In this small lens, a stop is disposed between the first lens included in the first group and the object-side concave surface of the second group, and at least one surface of the lenses included in the second group and the third group is an aspherical surface. And the desired conditional expression is satisfied. As a result, it is possible to provide a small lens having a small size / high resolution and good workability and assemblability. Note that Patent Document 1 points out that, when a four-lens lens is used, it is necessary to add a member that embodies flare cut and aperture.

JP, 2006-301230, A

  In order to realize a high-resolution imaging lens system, it is easiest to simply increase the number of lenses constituting the imaging lens system. As the number of lenses increases, the cost of the imaging lens system increases, but it is possible to prevent the manufacturing of the imaging lens system from becoming complicated. However, simply increasing the number of lenses increases the size of the imaging lens system, so even if it has a high resolution, it does not satisfy the demand for downsizing, and eventually the resolution / downsizing is sacrificed to some extent. No longer get.

  Thus, it is strongly required to provide the imaging lens system with high resolution in a manner that suppresses the increase in size of the imaging lens system.

  The imaging lens system according to the present invention includes at least a first lens group including a convex first lens on the object side, a second lens group including a concave second lens on the imaging side, and a concave surface on the object side. A third lens group including a third meniscus lens, a fourth lens group including a fourth meniscus lens having a concave surface on the object side, and an aspheric surface having an inflection point on the object side. An imaging lens system in which a fifth lens group including a meniscus fifth lens is arranged in this order from the object side, and the fifth lens is a cross-sectional view of the fifth lens in a plane including an optical axis. The first and second inflection points at which the extending direction of the outline of the fifth lens first changes in the direction away from the center of the fifth lens in the outer circumferential direction of the fifth lens are the object side surfaces on the object side. And on the imaging side on the imaging side It is a surface lens. Here, when the focal length of the imaging lens system is f, the height of the first inflection point from the optical axis is i1, and the height of the second inflection point from the optical axis is i2, It is preferable that i1 / f <0.20 is satisfied and i2 / f <0.26 is satisfied. The imaging lens system according to the present invention includes a first lens having positive power, a second lens having negative power, a third lens having positive power, a fourth lens having negative power, and an object side. An imaging lens system in which a meniscus fifth lens having an aspheric surface having an inflection point is arranged in this order from the object side, and the fifth lens is arranged in a plane including the optical axis. When the cross-sectional view is taken, the first inflection point is formed on the object side surface and the second inflection point is formed on the imaging side surface in the direction away from the center of the fifth lens in the outer circumferential direction of the fifth lens. Assuming the condition that the sag amount on the side is a positive value and the sag amount on the object side is a negative value, the sag amount from the optical axis position on the object side surface to the first inflection point is SL1, The sag amount from the first inflection point to the effective diameter position of the object side surface H1, and the sag amount from the optical axis position on the imaging side surface to the second inflection point is SL2, and the sag amount from the second inflection point to the effective diameter position on the imaging side surface is SH2. When SL1 and SL2 are positive values, SH1 and SH2 are negative values, and | SH1 / SL1 |> 2 and | SH2 / SL2 |> 2.5 are satisfied.

  The contour line constituting the object side surface approaches the object side as it extends from the first inflection point in the outer peripheral direction of the fifth lens, and the contour line constituting the imaging side surface is: It is preferable to approach the object side as it extends from the second inflection point toward the outer periphery of the fifth lens.

  Assuming that the sag amount toward the imaging side is a positive value and the sag amount toward the object side is a negative value, the sag amount from the optical axis position on the object side surface to the first inflection point is SL1. The amount of sag from the first inflection point to the effective diameter position of the object side surface is SH1, the amount of sag from the optical axis position on the imaging side surface to the second inflection point is SL2, and the first When the amount of sag from the second inflection point to the effective diameter position of the imaging side surface is SH2, SL1 and SL2 are positive values, and SH1 and SH2 are preferably negative values.

  It is preferable that | SH1 / SL1 |> 2 is satisfied and | SH2 / SL2 |> 2.5 is satisfied.

  The second inflection point may be located closer to the outer periphery of the fifth lens than the first inflection point.

  When the focal length of the imaging lens system is f and the focal length of the first lens is f1, 0.45 <f1 / f <0.60 is preferably satisfied.

  When the focal length of the imaging lens system is f and the focal length of the second lens is f2, it is preferable that −0.75 <f1 / f2 <−0.60 is satisfied.

  When the focal length of the imaging lens system is f and the focal length of the third lens is f3, it is preferable that 1.50 <f3 / f <3.50 is satisfied.

  The first lens has a positive power, the second lens has a negative power, the third lens has a positive power, the fourth lens has a negative power, and the The fifth lens preferably has positive or negative power.

  The fifth lens preferably has the largest lens diameter among the lenses included in the imaging lens system. The third to fifth lenses preferably have a lens diameter that increases in this order. The first lens group may be composed of a plurality of lenses. The camera module according to the present invention preferably includes the above-described imaging lens system and an image sensor that captures an image formed through the plurality of lenses.

  According to the present invention, it is possible to provide a high resolution to the imaging lens system in a manner that suppresses an increase in the size of the imaging lens system.

1 is a schematic configuration diagram of a camera module according to a first embodiment of the present invention. It is a schematic structure schematic diagram of a lens included in the imaging lens system according to the first embodiment of the present invention. It is a schematic structure schematic diagram of the camera module according to the first embodiment of the present invention. It is a table | surface which shows various conditions of the imaging lens system which concerns on 1st Example of this invention. It is a table | surface which shows the aspherical coefficient of the aspherical lens which concerns on 1st Example of this invention. FIG. 6 is an aberration diagram showing lateral aberration of the imaging lens system according to Example 1 of the present invention. FIG. 6 is an aberration diagram showing spherical aberration of the imaging lens system according to Example 1 of the present invention. FIG. 6 is a characteristic diagram showing field curvature and distortion of the imaging lens system according to the first example of the present invention. It is a schematic structure schematic diagram of the camera module according to the first embodiment of the present invention. It is a table | surface which shows various conditions of the imaging lens system which concerns on 2nd Example of this invention. It is a table | surface which shows the aspherical coefficient of the aspherical lens which concerns on 2nd Example of this invention. FIG. 6 is an aberration diagram showing lateral aberration of the imaging lens system according to Example 2 of the present invention. FIG. 6 is an aberration diagram showing spherical aberration of the imaging lens system according to Example 2 of the present invention. It is a characteristic view which shows the curvature of field and distortion of the imaging lens system which concerns on 2nd Example of this invention. It is a schematic structure schematic diagram of the camera module which concerns on 3rd Example of this invention. It is a table | surface which shows the various conditions of the imaging lens system which concerns on 3rd Example of this invention. It is a table | surface which shows the aspherical coefficient of the aspherical lens which concerns on 3rd Example of this invention. FIG. 6 is an aberration diagram showing lateral aberration of the imaging lens system according to Example 3 of the present invention. FIG. 6 is an aberration diagram showing spherical aberration of the imaging lens system according to Example 3 of the present invention. FIG. 6 is a characteristic diagram showing field curvature and distortion of the imaging lens system according to Example 3 of the present invention. It is a schematic structure schematic diagram of a camera module according to a fourth embodiment of the present invention. It is a table | surface which shows various conditions of the imaging lens system which concerns on 4th Example of this invention. It is a table | surface which shows the aspherical coefficient of the aspherical lens which concerns on 4th Example of this invention. FIG. 10 is an aberration diagram showing lateral aberration of the imaging lens system according to Example 4 of the present invention. FIG. 10 is an aberration diagram showing spherical aberration of the imaging lens system according to Example 4 of the present invention. It is a characteristic view which shows the field curvature and distortion of the imaging lens system which concerns on 4th Example of this invention. It is a schematic structure schematic diagram of a camera module according to a comparative example of the present invention. It is a schematic structure schematic diagram of a camera module according to a fifth embodiment of the present invention. It is a table | surface which shows the various conditions of the imaging lens system which concerns on 5th Example of this invention. It is a table | surface which shows the aspherical coefficient of the aspherical lens which concerns on 5th Example of this invention. FIG. 10 is an aberration diagram showing lateral aberration of the imaging lens system according to Example 5 of the present invention. FIG. 10 is an aberration diagram showing spherical aberration of the imaging lens system according to Example 5 of the present invention. FIG. 10 is a characteristic diagram showing field curvature and distortion of an imaging lens system according to Example 5 of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each embodiment is simplified for convenience of explanation. Since the drawings are simple, the technical scope of the present invention should not be interpreted narrowly based on the drawings. The drawings are only for explaining the technical matters, and do not reflect the exact sizes or the like of the elements shown in the drawings. The same elements are denoted by the same reference numerals, and redundant description is omitted. Words indicating directions such as up, down, left, and right are used on the assumption that the drawing is viewed from the front.

[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the camera module (image acquisition device) 100 includes a diaphragm member 50, a lens 1, a lens 2, a lens 3, a lens 4, a lens 5, a transparent substrate 10, and an image sensor (imaging device) 20. .

  The diaphragm member 50, the lens 1, the lens 2, the lens 3, the lens 4, the lens 5, the transparent substrate 10, and the image sensor 20 are arranged in this order along the optical axis AX. The lenses 1 to 5 are fixed to a lens holder (not shown), and a space (air layer) is provided between adjacent lenses. That is, the lenses 1 to 5 are arranged so as to be separated from each other, and one is not fixed (integrated) to the other lens by bonding or the like.

  The light beam coming from the object side reaches the imaging surface 25 of the image sensor 20 through the aperture OP50 of the diaphragm member 50, the lenses 1 to 5, and the transparent substrate 10. A plurality of pixels are arranged in a matrix on the imaging surface 25 of the image sensor 20 on the zy plane. Each pixel photoelectrically converts input light, and accumulates / generates a charge of a charge amount according to the intensity of the input light. By reading the charge accumulated / generated in each pixel from each pixel and converting the read analog value into a digital value, the light image formed on the imaging surface 25 of the image sensor 20 is converted into image data. The

  The aperture member 50 has an opening OP50 at a position corresponding to the optical axis AX. The diaphragm member 50 is, for example, a ring-shaped member molded with black resin.

  The lens 1 is an aspheric lens constituting the first lens group. The lens 1 has a convex lens surface on the object side. The lens 1 has a positive power. The lens 1 is manufactured by molding a material such as glass or plastic.

  The lens 2 is an aspheric lens constituting the second lens group. The lens 2 has a concave lens surface on the image forming side. The lens 2 has negative power. The lens 2 is manufactured by molding a material such as glass or plastic.

  The lens 3 is an aspheric lens constituting the third lens group. The lens 3 has a concave lens surface on the object side and a convex lens surface on the image formation side. That is, the lens 3 is a meniscus lens having a concave surface facing the object side. The lens 3 has a positive power. The lens 3 is manufactured by molding a material such as glass or plastic.

  The lens 4 is an aspheric lens constituting the fourth lens group. The lens 4 has a concave lens surface on the object side and a convex lens surface on the image formation side. That is, the lens 4 is a meniscus lens having a concave surface facing the object side. The lens 4 has negative power. The lens 4 is manufactured by molding a material such as glass or plastic.

The lens 5 is an aspheric lens constituting the fifth lens group. The lens 5 has a convex lens surface 5a on the object side and a concave lens surface 5b on the imaging side. That is, the lens 5 is a meniscus lens having a convex surface facing the object side. In other words, the lens 5 is a meniscus lens in which an aspheric surface having an inflection point is disposed on the object side. The lens surface 5a is convex at a position corresponding to the optical axis AX, but has a concave lens surface as a whole. The lens surface 5b is a convex lens surface as a whole, but has a concave lens surface at a position corresponding to the optical axis AX. The lens 5 has positive or negative power. The lens 5 is manufactured by molding a material such as glass or plastic. In general, the upper and lower molds are laminated, and a resin or glass is filled in a space formed between the upper and lower molds, and these are cooled, so that the individual lenses are collectively. Manufactured.

As schematically shown in FIG. 1, when the lens 5 is viewed in cross section in a plane including the optical axis AX (a plane parallel to the optical axis AX and including the optical axis AX), the lens 5 has an inflection point 5p, It has an inflection point 5q, and has a center point 5r and a center point 5s. The inflection point 5p corresponds to the intersection of the axis parallel to the optical axis AX and the lens surface 5a. The inflection point 5q corresponds to the intersection of the axis line x4 parallel to the optical axis AX and the lens surface 5b. The center point 5r corresponds to the intersection of the optical axis AX and the lens surface 5a.
The center point 5s corresponds to the intersection of the optical axis AX and the lens surface 5b.

The inflection point is located at a position where the outline of the lens extending from the optical axis AX toward the outer periphery of the lens changes its direction. In other words, the inflection point is at a position where the bending direction of the lens outline changes.
The contour line appears when the lens is viewed in cross section on a plane including the optical axis AX.

  The contour line extends as follows. The contour line constituting the lens surface 5a of the lens 5 extends upward (outer peripheral side) starting from the center point 5r. First, the contour line extends from the center point 5r to the inflection point 5p while approaching the imaging side. Next, the contour line extends upward from the inflection point 5p while approaching the object side. The same description applies to the lower side (outer peripheral side).

  The contour line constituting the lens surface 5b of the lens 5 extends upward (outer peripheral side) starting from the center point 5s. First, the contour line extends from the center point 5s to the inflection point 5q while approaching the imaging side. Next, the contour line extends upward from the inflection point 5q while approaching the object side. The same description applies to the lower side (outer peripheral side).

  The inflection point 5p is located closer to the optical axis AX than the inflection point 5q. The inflection point 5q is located on the outer peripheral side of the lens 5 with respect to the inflection point 5p. In other words, the height i1 of the inflection point 5p from the optical axis AX is smaller than the height i2 of the inflection point 5q from the optical axis AX. By setting the position of the inflection point in this way, it is possible to effectively reduce the size of the lens 5 while maintaining desired lens characteristics.

  The height i1 of the inflection point 5p corresponds to the distance between the optical axis AX and the axis x2 (the length of the axis x1). Similarly, the height i2 of the inflection point 5q corresponds to the distance between the optical axis AX and the axis x4 (the length of the axis x3). The axis line x1 is a perpendicular line of the optical axis AX and extends to the intersection with the axis line x2. The axis line x3 is a perpendicular line of the optical axis AX and extends to the intersection with the axis line x4.

  The inflection points in the lower half portion of the optical axis AX when viewed from the front in FIG. 1 are the same as the inflection points 5p and 5q, and thus redundant explanations are omitted.

In this embodiment, as schematically shown in FIG. 1, the focal length of the entire system of lenses 1 to 5 is f, the height from the optical axis AX to the inflection point 5p is i1, and the optical axis AX When the height from the point to the inflection point 5q is i2, the following conditional expressions (1) and (2) are satisfied.
i1 / f <0.20 (1)
i2 / f <0.26 (2)

  The focal length f of the entire lens system corresponds to the distance between the rear principal point position of the entire lens system and the imaging surface of the image sensor 20, as schematically shown in FIG. The height from the optical axis AX to the inflection point is as described above.

  As described above, the lens 5 can be effectively downsized by providing the lens surfaces 5a and 5b with inflection points and satisfying the conditional expressions (1) and (2). Become. When the upper limit value of conditional expressions (1) and (2) is exceeded, the lens diameter of the lens 5 must be increased, and it becomes difficult to sufficiently downsize the imaging lens system.

  As is apparent from FIG. 1, the lens 5 is a lens having the largest lens diameter. By enabling the lens 5 having the largest lens diameter to be miniaturized, even if a configuration in which five lenses are simply arranged is employed, it is possible to suppress the enlargement of the lens outside the allowable range, and to achieve high resolution. It is possible to easily realize an imaging lens system having a compact size. There is no need to join the lenses 1 to 5, and the lens 1 to the lens 5 may be simply attached to the lens holder.

  Further explanation will be given with reference to FIG.

  As shown in FIG. 2, when the sag amount on the imaging side is a positive (+) value and the sag amount on the object side is a negative (−) value, it can be explained as follows. The sag amount SL1 from the center point 5r to the inflection point 5p is a positive value. The sag amount SH1 from the inflection point 5p to the effective diameter position 5t is a negative value. The sag amount SL2 from the center point 5s to the inflection point 5q is a positive value. The sag amount SH2 from the inflection point 5q to the effective diameter position 5u is a negative value.

At this time, the following conditional expressions (3) and (4) are preferably satisfied.
| SH1 / SL1 |> 2 (3)
| SH2 / SL2 |> 2.5 (4)

  When the conditional expressions (3) and (4) are satisfied, the lens system of the lens 5 can be effectively reduced. This makes it possible to sufficiently reduce the size of the imaging lens system. The effective diameter position corresponds to a point on the effective diameter.

  The sag amount SL1 corresponds to the interval between the axis line x5 and the axis line x6. The sag amount SL2 corresponds to the interval between the axis line x8 and the axis line x9. The sag amount SH1 corresponds to the interval between the axis line x6 and the axis line x7. The sag amount SH2 corresponds to the interval between the axis x9 and the axis x10.

  The axis x5 exists on the center point 5r and intersects the optical axis AX perpendicularly. The axis x6 exists on the inflection point 5p and intersects the optical axis AX perpendicularly. The axis x7 exists on the effective diameter position 5t and intersects the optical axis AX perpendicularly. The axis line x8 exists on the center point 5s and intersects the optical axis AX perpendicularly. The axis x9 exists on the inflection point 5q and intersects the optical axis AX perpendicularly. The axis line x10 exists on the effective diameter position 5u and intersects the optical axis AX perpendicularly.

Returning to FIG. As shown in FIG. 1, the distance between the center point 1p of the lens surface 1a of the lens 1 and the imaging surface 25 of the image sensor 20 is TL, and the distance between the center point 1p of the lens surface 1a of the lens 1 and the lens surface 5b of the lens 5 is. When the interval between the center points 5s is LL, the following conditional expressions (5) and (6) are satisfied.
1.05 <TL / f <1.14 (5)
0.70 <LL / f <0.80 (6)

  If the upper limit value of conditional expression (5) is exceeded, the total length of the camera module 100 becomes long, and it becomes difficult to make the camera module 100 thinner. If the lower limit of conditional expression (5) is not reached, the focal length f becomes long, a sufficient angle of view cannot be obtained, and it becomes difficult to ensure the performance of the imaging lens system. In addition, the thickness and edge thickness of each lens become thin, making its manufacture difficult.

  When the upper limit value of conditional expression (6) is exceeded, the lens system of each lens becomes large, and it becomes difficult to reduce the size of the imaging lens system. If the lower limit of conditional expression (6) is not reached, it will be difficult to ensure the performance of the imaging lens system. In addition, the thickness and edge thickness of each lens become thin, making its manufacture difficult.

  In the present embodiment, by satisfying the conditional expressions (5) and (6), the camera module 100 can be downsized / thinned while suppressing the performance deterioration of the imaging lens system.

When the focal length of the lens 1 is f1, the focal length of the lens 2 is f2, and the focal length of the lens 3 is f3, the following conditional expressions (7), (8), and (9) are satisfied. .
0.45 <f1 / f <0.60 (7)
−0.75 <f1 / f2 <−0.60 (8)
1.50 <f3 / f <3.50 (9)

  If the upper limit value of conditional expression (7) is exceeded, the overall length of the imaging lens system becomes long, and it becomes difficult to reduce the thickness of the camera module 100. If the lower limit value of conditional expression (7) is not reached, the lower coma aberration of the imaging lens system will increase, making it difficult to correct. If the conditional expression (8) is not satisfied, it becomes difficult to correct chromatic aberration appropriately. When the conditional expression (9) is not satisfied, it is difficult to appropriately correct the field curvature.

  In the present embodiment, satisfying conditional expressions (7), (8), and (9) makes it possible to obtain desired characteristics of the imaging lens system. By satisfying these conditional expressions (7) to (9), the imaging lens system is reduced in size while suppressing the deterioration of the performance of the imaging lens system. As a result, the camera module 100 incorporating the same is reduced in size. / Thinning can be achieved.

[First embodiment]
The first embodiment will be described with reference to FIGS. As shown in FIG. 3, the camera module 100 according to the first example has the same configuration as that of the first embodiment. The camera module 100 according to the first embodiment satisfies all the conditional expressions (1) to (9).

  The imaging lens system according to the present example is configured under the conditions shown in FIG. The surface numbers are set as i = 1, i = 2,... In order from the object side. The surface of i = 1 is the object side lens surface of the lens 1. The surface of i = 2 is the imaging side lens surface of the lens 1. The surface of i = 3 is the object side lens surface of the lens 2. The surface of i = 4 is the image forming side lens surface of the lens 2. The same applies to other surface numbers. However, the surface of i = 11 is the front surface (input surface) of the transparent substrate 10. The i = 12 surface is the rear surface (output surface) of the transparent substrate 10.

  The surface interval is the distance to the immediately following surface. For example, the surface distance Di of i = 2 is the distance from the lens surface of i = 2 to the lens surface of i = 3. However, the surface interval Di of i = 12 indicates the distance from the lens surface i = 12 to the imaging surface.

ただし、サグ量：Ｚ、光軸からの高さ：h、曲率：c、円錐係数：k、非球面係数：α_2iとする。 The lenses 1 to 5 are aspheric lenses and are represented by aspheric coefficients as shown in FIG. The aspheric shape is expressed by the following equation (10).

However, the sag amount is Z, the height from the optical axis is h, the curvature is c, the conic coefficient is k, and the aspheric coefficient is α _2i .

FIG. 6 is an aberration diagram showing lateral aberration of the imaging lens system. FIG. 7 is an aberration diagram showing the spherical aberration of the imaging lens system. FIG. 8 is a characteristic diagram showing the field curvature of the imaging lens system (left side toward the paper surface) and a characteristic diagram showing the distortion (right side toward the paper surface). As is clear from these drawings, the imaging lens system according to the present embodiment has sufficient performance to cope with the recent increase in the number of pixels. In FIG. 6 to FIG. 8, the solid line indicates the case of a wavelength of 546 nm. A rougher broken line indicates a case of a wavelength of 656 nm. A finer broken line indicates a case where the wavelength is 486 nm. These points are the same in the embodiments described later.
Further, the upper left portion of FIG. 6 shows lateral aberration when the half angle of view is 0.00 DEG. The upper right part of FIG. 6 shows the lateral aberration when the half angle of view is 24.10 DEG. The lower part of FIG. 6 shows the lateral aberration when the half angle of view is 32.80 DEG.

[Second Embodiment]
A second embodiment will be described with reference to FIGS. As shown in FIG. 9, the camera module 100 according to the second example has the same configuration as that of the first embodiment. The camera module 100 according to the second embodiment satisfies all the conditional expressions (1) to (9).

  The imaging lens system according to the present example is configured under the conditions shown in FIG. The surface numbers are set as i = 1, i = 2,... Sequentially from the object side, as in the case described above. The surface spacing is the same as that described above.

  The lenses 1 to 5 are aspherical lenses and are represented by aspherical coefficients as shown in FIG. The aspherical shape is the same as the above-described formula (10).

  FIG. 12 is an aberration diagram showing the lateral aberration of the imaging lens system. FIG. 13 is an aberration diagram showing the spherical aberration of the imaging lens system. FIG. 14 shows a characteristic diagram showing the curvature of field of the imaging lens system (left side toward the paper surface) and a characteristic diagram showing the distortion (right side toward the paper surface). As is apparent from these drawings, the imaging lens system according to the present embodiment has sufficient performance to cope with the recent increase in the number of pixels. In addition, the upper left part of FIG. 12 shows the lateral aberration when the half angle of view is 0.00 DEG. The upper right part of FIG. 12 shows the lateral aberration when the half angle of view is 23.50 DEG. The lower part of FIG. 12 shows the lateral aberration when the half angle of view is 32.00 DEG.

[Third embodiment]
A third embodiment will be described with reference to FIGS. As shown in FIG. 15, the camera module 100 according to the third example has the same configuration as that of the first embodiment. The camera module 100 according to the third embodiment satisfies all the conditional expressions (1) to (9).

  The imaging lens system according to the present example is configured under the conditions shown in FIG. The surface numbers are set as i = 1, i = 2,... Sequentially from the object side, as in the case described above. The surface spacing is the same as that described above.

  The lenses 1 to 5 are aspheric lenses and are represented by aspheric coefficients as shown in FIG. The aspherical shape is the same as the above-described formula (10).

  FIG. 18 is an aberration diagram showing lateral aberration of the imaging lens system. FIG. 19 is an aberration diagram showing spherical aberration of the imaging lens system. FIG. 20 shows a characteristic diagram showing the curvature of field of the imaging lens system (left side toward the paper surface) and a characteristic diagram showing the distortion (right side toward the paper surface). As is apparent from these drawings, the imaging lens system according to the present embodiment has sufficient performance to cope with the recent increase in the number of pixels. In addition, the upper left part of FIG. 18 shows the lateral aberration when the half angle of view is 0.00 DEG. The upper right part of FIG. 18 shows the lateral aberration when the half angle of view is 23.80 DEG. The lower part of FIG. 18 shows the lateral aberration when the half angle of view is 32.30 DEG.

[Fourth embodiment]
A fourth embodiment will be described with reference to FIGS. As shown in FIG. 21, the camera module 100 according to the fourth example has the same configuration as that of the first embodiment. The camera module 100 according to the fourth example satisfies all the conditional expressions (1) to (9).

  The imaging lens system according to the present example is configured under the conditions shown in FIG. The surface numbers are set as i = 1, i = 2,... Sequentially from the object side, as in the case described above. The surface spacing is the same as that described above.

  The lenses 1 to 5 are aspheric lenses and are represented by aspheric coefficients as shown in FIG. The aspherical shape is the same as the above-described formula (10).

  FIG. 24 is an aberration diagram showing lateral aberration of the imaging lens system. FIG. 25 is an aberration diagram showing spherical aberration of the imaging lens system. FIG. 26 shows a characteristic diagram showing the curvature of field of the imaging lens system (left side toward the paper surface) and a characteristic diagram showing the distortion (right side toward the paper surface). As is apparent from these drawings, the imaging lens system according to the present embodiment has sufficient performance to cope with the recent increase in the number of pixels. In addition, the upper left part of FIG. 24 shows the lateral aberration when the half angle of view is 0.00 DEG. The upper right part of FIG. 24 shows the lateral aberration when the half angle of view is 24.30 DEG. The lower part of FIG. 24 shows the lateral aberration when the half angle of view is 33.00 DEG.

[Comparative example]
A comparative example will be described with reference to FIG. As shown in FIG. 27, the imaging lens system according to the comparison system does not satisfy the conditional expressions (1) to (6) unlike the first embodiment. In such a case, the lens 5 cannot be reduced in size, the entire length of the imaging lens system increases, and it becomes difficult to reduce the thickness / size of the camera module 100. In the case of the comparative example, the conditional expressions (7) to (9) are satisfied.

[Fifth embodiment]
A fifth embodiment will be described with reference to FIGS. As shown in FIG. 28, unlike the first embodiment, the camera module 100 according to the fifth example includes six lens groups. Even in such a case, the same effect as the first embodiment can be obtained.
That is, the same effect can be obtained even when the number of lens groups is five or more. Note that the camera module 100 according to the fifth example satisfies all the conditional expressions (1) to (9).

  As shown in FIG. 28, a lens 6 is newly disposed on the object side of the lens 1. The lens 6 is an aspheric lens constituting the first lens group. The lens 6 has a slightly convex lens surface on the object side, and has a slightly concave lens surface on the imaging side. The lens 6 has a positive power. The lens 6 is manufactured by molding a material such as glass or plastic.

  The imaging lens system according to the present example is configured under the conditions shown in FIG. The surface numbers are set as i = 1, i = 2,... Sequentially from the object side, as in the case described above. The surface spacing is the same as that described above.

  The lenses 1 to 6 are aspheric lenses and are represented by aspheric coefficients as shown in FIG. The aspherical shape is the same as the above-described formula (10).

  FIG. 31 is an aberration diagram showing lateral aberration of the imaging lens system. FIG. 32 is an aberration diagram showing spherical aberration of the imaging lens system. FIG. 33 shows a characteristic diagram showing the field curvature of the imaging lens system (left side toward the paper surface) and a characteristic diagram showing the distortion (right side toward the paper surface). As is apparent from these drawings, the imaging lens system according to the present embodiment has sufficient performance to cope with the recent increase in the number of pixels. In addition, the upper left part of FIG. 31 shows the lateral aberration when the half angle of view is 0.00 DEG. The upper right part of FIG. 31 shows the lateral aberration when the half angle of view is 23.00 DEG. The lower part of FIG. 31 shows the lateral aberration when the half angle of view is 31.30 DEG.

Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. The specific configuration of the imaging lens system is arbitrary. The material of the lens is arbitrary. The number of lenses constituting the lens group is arbitrary.
The position of the diaphragm 50 can be changed according to the purpose, and is not limited to the present embodiment and examples.
Specifically, in the first to fourth embodiments described above, the diaphragm 50 is disposed on the object side of the first lens 1. This is to prevent the incident angle of the light beam on the image sensor 20 from becoming too large. Therefore, when using an image sensor in which the incident angle of the light beam may be large, the diaphragm 50 does not need to be disposed on the object side of the first lens 1, and for example, the first lens 1 and the second lens 2. You may arrange | position between lens systems, such as between.
In the fifth embodiment, the stop is disposed between the sixth lens 6 and the first lens 1. When the stop is disposed on the object side of the sixth lens 6, there is a disadvantage that the lens diameter is increased, but there is an advantage that the incident angle to the image sensor 20 is reduced.

100 Camera module 50 Aperture member 1-6 Lens 10 Transparent substrate 20 Image sensor 1a Lens surface 1p Center point 5a Lens surface 5b Lens surface 5p Inflection point 5q Inflection point 5r Center point 5s Center point 5t Effective diameter position 5u Effective diameter position

Claims (5)

A first lens having positive power;
A second lens having negative power;
A third lens having positive power;
A fourth lens having negative power;
And a meniscus fifth lens having an aspheric surface having an inflection point on the object side,
An imaging lens system arranged in this order from the object side,
When the fifth lens is a cross-sectional view of the fifth lens in a plane including the optical axis,
In the direction away from the center of the fifth lens in the outer circumferential direction of the fifth lens,
Having a first inflection point on the object side and a second inflection point on the imaging side;
Assuming the condition that the sag amount toward the imaging side is a positive value and the sag amount toward the object side is a negative value,
The sag amount from the optical axis position on the object side surface to the first inflection point is SL1, and the sag amount from the first inflection point to the effective diameter position on the object side surface is SH1, and on the imaging side surface SL1 and SL2 are positive when the sag amount from the optical axis position to the second inflection point is SL2 and the sag amount from the second inflection point to the effective diameter position of the imaging side surface is SH2. An imaging lens system, wherein SH1 and SH2 are negative values, and | SH1 / SL1 |> 2 and | SH2 / SL2 |> 2.5 are satisfied.   2. The imaging lens system according to claim 1, wherein the second inflection point is located on an outer peripheral side of the fifth lens with respect to the first inflection point.   The imaging lens system according to claim 1, wherein the fifth lens has a largest lens diameter among lenses included in the imaging lens system.   The imaging lens system according to claim 1, wherein the third to fifth lenses have a lens diameter that increases in this order.   The imaging lens system according to claim 1, wherein the first lens group includes a plurality of lenses.

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