JP2009265451A - Thin-type optical lens group for taking photo - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-type optical lens group for taking photos, which is excellent in imaging quality and effectively reduces the volume of the lens group itself. <P>SOLUTION: The thin-type optical lens group for taking photos comprises a first lens 10 having positive refractive power, a nonspherical second lens 20 having negative refractive power and a nonspherical third lens 30 having negative refractive power, these lenses being arranged in the order from the object side toward the image side. Furthermore, an aperture 40, which is arranged between the first lens 10 and the second lens 20 and controls the luminous intensity of the thin-type optical lens group for taking photos, is provided in this lens group. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an optical lens set, and more particularly to a thin-type optical lens set for photographing applied to a mobile phone capable of photographing.

Recently, with the widespread use of mobile phones that can shoot, the need for miniature optical lenses for shooting has increased, and the only photosensitive element for general shooting optical lenses is CMOS or CCD, and with the progress of semiconductor manufacturing technology As a result, the area of the pixels of the photosensitive element is also reduced. Therefore, the number of pixels of the mini optical lens for photographing is increased, and the requirement for the imaging quality is becoming strict.

However, the conventional photographing lens group of a mobile phone has a first lens having a positive refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power from the object side. These are arranged in order on the image side, which is also referred to as a “Triplet type lens set”. This type of lens set has a problem that the stop is placed in front to correct astigmatism of the system, but this increases the scattering of light rays and increases the sensitivity of the system. .

A main object of the present invention is to provide a thin-type optical lens set for photographing that can improve imaging quality and can effectively reduce the volume of the lens set.

In order to improve the imaging quality and effectively reduce the volume of the lens assembly, the thin-type optical lens assembly for photographing according to the first invention of the present invention has refractive power and sequentially arranges from the object side to the image side. The first lens having a positive refractive power, a stop, an aspherical second lens having a negative refractive power, and an aspherical third lens having a negative refractive power, and the like. .

The photographic optical lens set of the present invention is provided by a first lens whose system refractive power is mainly positive refractive power, a second lens having negative refractive power and a third lens having negative refractive power, The function of the correction lens is exhibited to balance and correct each astigmatism of the system.

Due to the strong positive refractive power provided by the first lens, the total length of the thin optical lens set for photographing can be shortened when the diaphragm is placed on the object side. The system exit pupil (Exit Pupil) moves away from the imaging plane, and then the light beam enters the photosensitive element in a vertically approaching manner, which is the telecentric characteristic of the imaging side, while the third lens Because the aspherical surface of this is provided with an inflection point, the angle deviated from the axial direction of the light beam that can enter the photosensitive element is suppressed, and the telecentric characteristic is extremely important for the photosensitive ability of the solid-state electro-sensitive element. Yes, the Telecentric characteristic increases the sensitivity of the electro-sensitive element and reduces the possibility of dark angles in the system. Also, in wide-angle optical systems, it is extremely necessary to correct distortion and chromatic aberration of magnification (Chromatic Aberration of Magnification), and the method is to install a diaphragm at the balance of the refractive power of the light beams in the system. In addition, in the thin-type optical lens group for photographing according to the present invention, the diaphragm is installed between the first lens and the second lens, and the daily balance is between the telecentric characteristic and the wide viewing angle characteristic. If the diaphragm is installed as described above, it is possible to effectively reduce the sensitivity of the thin optical lens set for photographing.

In addition, the focal length of the optical system is shortened in accordance with the demand for a compact torrent of a photographing lens set for a mobile phone capable of photographing and a system with a wider viewing angle, so the curvature radius and dimensions of the lens are reduced. The above-mentioned lens becomes smaller, and it is impossible to produce it by a traditional lens polishing method. Therefore, it is common to produce it by resin injection molding. When a lens is produced by injection molding, it is a low-cost, high-precision lens. By providing the lens with an aspheric surface, it becomes easy to make the lens into a shape other than the spherical surface, and more control parameters can be obtained, thereby reducing astigmatism. The number of lenses can be reduced.

In the thin optical lens set for photographing according to the present invention, the first lens having positive refractive power may have a convex surface on the front surface, a convex surface on the back surface, or a concave surface, and the convex surface on the back surface of the first lens. In this case, the refractive power of the first lens is further increased, and the total length of the thin optical lens set for photographing can be effectively shortened. If the back surface of the first lens is a concave surface, The second lens having negative refractive power can effectively reduce scattering of the light beam of the lens, and the front surface is concave, the rear surface is convex, and the third lens having negative refractive power is the front surface. Is a convex surface, and the back surface is a concave surface. With such an arrangement, the imaging quality can be effectively improved.

In the thin optical lens set for photographing according to the present invention, if the Abbe number of the first lens is V1, the Abbe number of the second lens is V2, and the Abbe number of the third lens is V3. , (V1 + V3) / 2−V2> 20, the chromatic aberration generated in the optical system can be effectively corrected, and in order to satisfy the above condition, the lens material It is necessary to adopt appropriately.

In the thin-type optical lens set for photographing according to the present invention, the focal length of the first lens is fl, the focal length of the second lens is f2, and the focal length of the third lens is f3. Assuming that the focal length of the entire optical lens group is f, the following three conditions are satisfied: 1.3 <f / fl <1.7, -0.5 <f / f2 <0, and -0.4 <f / f3 <0.

The function of the first lens is to provide the main refractive power of the thin optical lens set for photographing, and when f / f1 is smaller than the lower limit of the above relational expression, If the refractive power becomes insufficient, the total length of the optical system becomes too long, but if f / f1 is larger than the upper limit of the above relational expression, the high-level astigmatism of the thin optical lens set for shooting Aberration becomes too large. The function of the first lens is to correct the chromatic aberration of the thin optical lens for photographing. When f / f2 is larger than the upper limit of the above relational expression, the chromatic aberration of the thin optical lens set for photographing If f / f2 is smaller than the lower limit value of the above relational expression, it is difficult to suppress the angle at which the light beam enters the photosensitive element. The first lens exhibits the function of a correction lens, and its refractive power is smaller. Therefore, it is preferable that the first lens is within the above range. It is more preferable if the three conditions of 1.35 <f / fl <1.5, -0.3 <f / f2 <0, and -0.2 <f / f3 <0 are satisfied.

In the thin optical lens set for photographing according to the present invention, if the curvature radius of the front surface of the first lens is R1, and the curvature radius of the back surface of the first lens is R2, -0.9 <R1 / R2 <- Satisfy the condition of 0.1.

If R1 / R2 is out of the range of the above relational expression, it is difficult to correct astigmatism of the thin-type optical lens group for photographing.

In the thin optical lens set for photographing according to the present invention, if the curvature radius of the front surface of the second lens is R3 and the curvature radius of the back surface of the second lens is R4, 0.4 <R3 / R4 < Satisfy the condition of 1.0.

When R3 / R4 is smaller than the lower limit value of the above relational expression, the absolute value of R3 becomes relatively small, which makes the total length of the thin optical lens set for photographing too large, When R3 / R4 is larger than the upper limit value of the above relational expression, the absolute value of R3 becomes relatively large, which makes it difficult to correct the chromatic aberration of the thin optical lens set for photographing.

Further, in the thin optical lens set for photographing according to the present invention, if the curvature radius of the front surface of the third lens is R5 and the curvature radius of the rear surface of the third lens is R6, 0.6 <R5 / R6 <1.6. Satisfy the conditions.

When R5 / R6 is within the range of the above relational expression, it becomes easy to correct high-level astigmatism of the thin-type optical lens set for photographing.

The R1 / R2, R3 / R4 and R5 / R6 values satisfy the following three conditions: -0.8 <R1 / R2 <-0.5, 0.55 <R3 / R4 <0.85, and 0.9 <R5 / R6 <1.4 This is more preferable.

In the thin optical lens set for photographing according to the present invention, if the refractive index of the first lens is N1 and the refractive index of the third lens is N3, 1.54 <N1 <1.6 and 1.5 <N3 <1.6. And satisfy the condition.

When the refractive indexes of the first lens and the third lens satisfy the above relational expression, the compatibility of the optical resin material having the refractive index within the above range and the thin optical lens set for photographing is further improved.

Further, in the thin optical lens set for photographing according to the present invention, when the first lens is a glass product, the refractive power of the first lens is effectively improved, and as a result, the optical power of the thin optical lens set for photographing is increased. The total length can be shortened.

In the thin optical lens set for photographing according to the present invention, if the mirror surface angle at the back effective radius position of the third lens is ANG32, the condition of ANG32 <−10 degrees is satisfied.

The direction of the specular angle is “positive when the specular angle at the peripheral effective radius position is inclined toward the imaging side, and negative when the specular angle at the peripheral effective radius position is inclined toward the subject”. It is defined as

With the above relationship, the angle at which the light beam enters the photosensitive element can be effectively reduced, and the ability to correct off-axis astigmatism of the thin optical lens set for photographing is enhanced.

In the thin optical lens set for photographing according to the present invention, if the effective diameter height of the front surface of the third lens is SAG31, the condition of SAG31 <0.2 (mm) is satisfied.

Note that the effective diameter height direction is `` When the peripheral effective diameter height is toward the imaging side, it is positive, and when the peripheral effective diameter position is toward the object to be imaged. '' Is negative ”. If the above conditions are satisfied, off-axis light divergence can be avoided and the stability of the system increases.

In the thin optical lens set for photographing according to the present invention, the distance between the second lens and the third lens is T23, the center thickness of the second lens is CT2, and the center thickness of the third lens Assuming CT3, the conditions T23 / CT2 <0.3 and T23 / CT3 <0.3 are satisfied.

With the above relationship, the total optical length of the thin optical lens set for photographing can be effectively shortened. Further, if the conditions of T23 / CT3 <0.25 and T23 <0.15 (mm) are satisfied, the total optical length of the thin optical lens set for photographing can be further shortened.

In the thin optical lens set for photographing of the present invention, if the angle corresponding to the main light incident electro-sensitive element (Chief Ray Angle) of the imaging height is CRA and half of the maximum field angle is HFOV, 0.45 <tan (CRA) / tan (HFOV) <1.15 is satisfied.

With the above relationship, the photographing thinned optical lens set becomes compatible with the electro-sensitive element, and the photographing thinned optical lens set has a wide viewing angle characteristic.

In the thin optical lens set for photographing according to the present invention, an object to be photographed of the thin optical lens set for photographing is imaged on an electro-sensitive element, and the total optical length of the thin optical lens set for photographing is TTL. If the imaging height of the thin optical lens set for photographing is ImgH, the condition of TTL / ImgH <2.65 is satisfied.

With the above relationship, it is possible to maintain the characteristics of downsizing the thin optical lens set for photographing.

According to the thin-type optical lens group for photographing according to the present invention, the imaging quality is improved, and the volume of the lens group can be effectively reduced.

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

First, refer to FIG. 1 and FIG. FIG. 1 is a schematic diagram of the optical system of the first embodiment of the present invention, and FIG. 2 is an astigmatism curve garden of the first embodiment of the present invention. The thin-type optical lens set for photographing according to the first embodiment of the present invention mainly has a first lens 10 having a positive refractive power and a negative refractive power, which are sequentially arranged from the object side to the image side. The second lens 20, a third lens 30 having a negative refractive power, and three lenses having a refractive power.

The first lens 10 is made of resin crystal, and the front surface 11 and the back surface 12 are convex and aspherical.

The second lens 20 is a resin product, the front surface 21 is concave, the back surface 22 is convex, and the front surface 21 and the back surface 22 are aspheric.

The third lens 30 is made of resin crystal, the front surface 31 is convex, the back surface 32 is concave, the front surface 31 and the back surface 32 are aspherical, and the front surface 31 and the back surface 32 have inflection points. Is provided.

The diaphragm 40 of the thin optical lens set for photographing is installed between the first lens 10 and the second lens 20 and controls the light intensity of the thin optical lens set for photographing.

Further, the infrared filter 50 (IR Filter) placed behind the third lens 30 and an image plane 60 placed behind the infrared filter 50, the infrared filter 50 is installed. Does not affect the focal length of the optical system. The equation for the aspheric curve is as follows.

そして、Xはレンズの断面距離であり、Yは非球面曲線での点と光軸との距離であり、kは錐面係数であり、Aiは、i番目の非球面係数である。

X is the cross-sectional distance of the lens, Y is the distance between the point on the aspheric curve and the optical axis, k is the conical surface coefficient, and Ai is the i-th aspheric coefficient.

Further, in the thin optical lens set for photographing according to the first embodiment of the present invention, the focal length of the first lens is f1, the focal length of the second lens is f2, and the focal length of the third lens is f3. Assuming that the focal length of the entire thin optical lens set for photographing is f, the following three conditions are satisfied: f / f1 = -1.320, f / f2 = -0.180, and f / f3 = -0.020.

Further, in the thin optical lens set for photographing of the first embodiment of the present invention, the Abbe number of the first lens is V1, the Abbe number of the second lens is V2, and the Abbe number of the third lens is V3. Then, the condition of (V1 + V3) /2−V2=26.2 is satisfied.

Further, in the thinned optical lens set for photographing of the first embodiment of the present invention, if the refractive index of the first lens is N1, and the refractive index of the third lens is N3, N1 = 1.543, and N3 = Satisfies the condition of 1.53.

Further, in the thinned optical lens set for photographing of the first embodiment of the present invention, the curvature radius of the front surface of the first lens is R1, the curvature radius of the back surface of the first lens is R2, and the second lens If the radius of curvature of the front surface is R3, the radius of curvature of the back surface of the second lens is R4, the radius of curvature of the front surface of the third lens is R5, and the radius of curvature of the back surface of the third lens is R6, R1 Three conditions of /R2=-0.27, R3 / R4 = 0.70, and R5 / R6 = 1.14 are satisfied.

Further, in the thin-type optical lens set for photographing according to the first embodiment of the present invention, if the mirror surface angle at the back effective radius position of the third lens is ANG32, the condition of ANG32 = −23.3 degrees is satisfied.

The direction of the specular angle is “positive when the specular angle at the peripheral effective radius position is inclined toward the imaging side, and negative when the specular angle at the peripheral effective radius position is inclined toward the subject”. It is defined as

In the thin optical lens set for photographing according to the present invention, when the height of the effective diameter of the front surface of the third lens is SAG31, the condition of SAG31 = 0.08 (mm) is satisfied.

Note that the effective diameter height direction is `` When the peripheral effective diameter height is toward the imaging side, it is positive, and when the peripheral effective diameter position is toward the object to be imaged. '' Is negative ”.

Further, in the thin optical lens set for photographing of the first embodiment of the present invention, the center thickness of the second lens is CT2, the center thickness of the third lens is CT3, the second lens and the first lens If the distance between the three lenses is T23, the conditions of T23 = 0.07 (mm), T23 / CT2 = 0.2, and T23 / CT3 = 0.17 are satisfied.

In the thinned optical lens set for photographing of the first embodiment of the present invention, the angle corresponding to the main beam incident electro-sensitive element (Chief Ray Angle) of the imaging height is CRA, and half of the maximum viewing angle is HFOV. Then, the condition (tan (CRA)) / (tan (HFOV)) = 0.84 is satisfied.

In the thin-type optical lens group for photographing according to the first embodiment of the present invention, an object to be photographed in the thin-type optical lens group for photographing is imaged on an electro-sensitive element, and the optical element of the thin-type optical lens group for photographing is used. If the total length is TTL and the imaging height of the thin optical lens set for shooting is ImgH, the condition of TTL / ImgH = 2.46 is satisfied.

Detailed data of the structure of the first embodiment of the present invention is shown in Table 1, the aspherical data is shown in Table 2, the radius, thickness and focal length units are mm, and HFOV is the maximum viewing angle. Defined as half of

Next, refer to FIG. 3 and FIG. FIG. 3 is a schematic diagram of the optical system of the second embodiment of the present invention, and the garden 4 is an astigmatism curve diagram of the second embodiment of the present invention.

The thin-type optical lens set for photographing according to the second embodiment of the present invention mainly has a first lens 10 having a positive refractive power and a negative refractive power, which are sequentially arranged from the object side to the image side. The second lens 20, a third lens 30 having a negative refractive power, and three lenses having a refractive power.

The first lens 10 is a resin product, and the front surface 11 and the back surface 12 are convex surfaces and aspherical surfaces.

The second lens 20 is made of resin crystal, the front surface 21 is concave, the back surface 22 is convex, and the front surface 21 and the back surface 22 are aspheric.

The third lens 30 is made of resin crystal, the front surface 31 is convex, the back surface 32 is concave, the front surface 31 and the back surface 32 are aspherical, and the front surface 31 and the back surface 32 have inflection points. Is provided.

The diaphragm 40 of the thin optical lens set for photographing is installed between the first lens 10 and the second lens 20 and controls the light intensity of the thin optical lens set for photographing.

Further, the infrared filter 50 (IR Filter) placed behind the third lens 30 and an image plane 60 placed behind the infrared filter 50, the infrared filter 50 is installed. Does not affect the focal length of the optical system.

The equation of the aspheric curve of the second embodiment is the same as that of the first embodiment.

Further, in the thin optical lens set for photographing of the second embodiment of the present invention, the focal length of the first lens is f1, the focal length of the second lens is f2, and the focal length of the third lens is f3. Assuming that the focal length of the entire thin optical lens set for photographing is f, the following three conditions are satisfied: f / f1 = 1.322, f / f2 = −0.182, and f / f3 = −0.022.

Further, in the thinned optical lens set for photographing according to the second embodiment of the present invention, the Abbe number of the first lens is V1, the Abbe number of the second lens is V2, and the Abbe number of the third lens is V3. Then, the condition of (V1 + V3) /2−V2=33.0 is satisfied.

In the thin-type optical lens set for photographing according to the second embodiment of the present invention, if the refractive index of the first lens is N1, and the refractive index of the third lens is N3, N1 = 1.543, and N3 = Satisfies the condition of 1.53.

Further, in the thinned optical lens set for photographing of the second embodiment of the present invention, the curvature radius of the front surface of the first lens is R1, the curvature radius of the back surface of the first lens is R2, and the second lens If the radius of curvature of the front surface is R3, the radius of curvature of the back surface of the second lens is R4, the radius of curvature of the front surface of the third lens is R5, and the radius of curvature of the back surface of the third lens is R6, R1 Three conditions of /R2=−0.68, R3 / R4 = 0.69, and R5 / R6 = 1.16 are satisfied.

Further, in the thinned optical lens set for photographing according to the second embodiment of the present invention, if the mirror surface angle at the back effective radius position of the third lens is ANG32, the condition of ANG32 = -12.6 degrees is satisfied.

The direction of the specular angle is “positive when the specular angle at the peripheral effective radius position is inclined toward the imaging side, and negative when the specular angle at the peripheral effective radius position is inclined toward the subject”. It is defined as

In the thin-type optical lens set for photographing according to the second embodiment of the present invention, if the effective diameter height of the front surface of the third lens is SAG31, the condition of SAG31 = 0.08 (mm) is satisfied.

Note that the effective diameter height direction is `` When the peripheral effective diameter height is toward the imaging side, it is positive, and when the peripheral effective diameter position is toward the object to be imaged. '' Is negative ”.

Further, in the thinned optical lens set for photographing according to the second embodiment of the present invention, the center thickness of the second lens is CT2, the center thickness of the third lens is CT3, the second lens and the first lens If the distance between the three lenses is T23, the conditions of T23 = 0.07 (mm), T23 / CT2 = 0.21, and T23 / CT3 = 0.19 are satisfied.

In addition, in the thinned optical lens set for photographing according to the second embodiment of the present invention, the angle corresponding to the main light incident electron photosensitive element at the imaging height (Chief Ray Angle) is CRA, and half of the maximum viewing angle is HFOV. Then, the condition (tan (CRA)) / (tan (HFOV)) = 0.72 is satisfied.

Further, in the thin optical lens set for photographing according to the second embodiment of the present invention, the object to be photographed of the thin optical lens set for photographing forms an image on an electro-sensitive element, and the optical of the thin optical lens set for photographing is used. If the total length is TTL and the imaging height of the thin optical lens set for shooting is ImgH, the condition of TTL / ImgH = 2.57 is satisfied.

Detailed data of the structure of the second embodiment of the present invention is shown in Table 3, the aspherical data is shown in Table 4, the unit of curvature radius, thickness and focal length is mm, HFOV is the maximum viewing angle Defined as half of

Next, refer to FIG. 5 and FIG. FIG. 5 is a schematic diagram of the optical system of the third embodiment of the present invention, and FIG. 6 is an astigmatism curve diagram of the third embodiment of the present invention.

The thin-type optical lens set for photographing according to the third embodiment of the present invention mainly has a first lens 10 having a positive refractive power and a negative refractive power, which are sequentially arranged from the object side to the image side. The second lens 20, a third lens 30 having a negative refractive power, and three lenses having a refractive power.

The first lens 10 is made of resin crystal, and the front surface 11 and the back surface 12 are convex and aspherical.

The second lens 20 is made of resin crystal, the front surface 21 is concave, the back surface 22 is convex, and the front surface 21 and the back surface 22 are aspheric.

The third lens 30 is made of resin crystal, the front surface 31 is convex, the back surface 32 is concave, the front surface 31 and the back surface 32 are aspherical, and the back surface 32 is provided with an inflection point. .

The diaphragm 40 of the thin optical lens set for photographing is installed between the first lens 10 and the second lens 20 and controls the light intensity of the thin optical lens set for photographing.

Further, the infrared filter 50 (IR Filter) placed behind the third lens 30 and an image plane 60 placed behind the infrared filter 50, the infrared filter 50 is installed. Does not affect the focal length of the optical system.

The equation of the aspheric curve of the third embodiment is the same as that of the first embodiment.

Further, in the thin optical lens set for photographing according to the third embodiment of the present invention, the focal length of the first lens is f1, the focal length of the second lens is f2, and the focal length of the third lens is f3. Assuming that the focal length of the entire photographing thinned optical lens set is f, the following three conditions are satisfied: f / f1 = 1.390, f / f2 = -0.190, and f / f3 = -0.100.

Further, in the thinned optical lens set for photographing according to the third embodiment of the present invention, the Abbe number of the first lens is V1, the Abbe number of the second lens is V2, and the Abbe number of the third lens is V3. Then, the condition of (V1 + V3) /2−V2=38.1 is satisfied.

Further, in the thinned optical lens set for photographing according to the third embodiment of the present invention, if the refractive index of the first lens is N1, and the refractive index of the third lens is N3, N1 = 1.593 and N3 = Satisfies the condition of 1.53.

Further, in the thinned optical lens set for photographing of the third embodiment of the present invention, the curvature radius of the front surface of the first lens is R1, the curvature radius of the back surface of the first lens is R2, and the second lens If the radius of curvature of the front surface is R3, the radius of curvature of the back surface of the second lens is R4, the radius of curvature of the front surface of the third lens is R5, and the radius of curvature of the back surface of the third lens is R6, R1 Three conditions are satisfied: /R2=-0.29, R3 / R4 = 0.70, and R5 / R6 = 1.30.

In the thin-type optical lens set for photographing according to the third embodiment of the present invention, if the mirror surface angle at the back effective radius position of the third lens is ANG32, the condition of ANG32 = −29.1 degrees is satisfied.

The direction of the specular angle is “positive when the specular angle at the peripheral effective radius position is inclined toward the imaging side, and negative when the specular angle at the peripheral effective radius position is inclined toward the subject”. It is defined as

Further, in the thin optical lens set for photographing according to the third embodiment of the present invention, when the height of the effective diameter of the front surface of the third lens is SAG31, the condition of SAG31 = 0.08 (mm) is satisfied.

Note that the effective diameter height direction is `` When the peripheral effective diameter height is toward the imaging side, it is positive, and when the peripheral effective diameter position is toward the object to be imaged. '' Is negative ”.

In the thinned optical lens set for photographing according to the third embodiment of the present invention, the center thickness of the second lens is CT2, the center thickness of the third lens is CT3, and the second lens and the second lens If the distance between the three lenses is T23, the conditions of T23 = 0.07 (mm), T23 / CT2 = 0.21, and T23 / CT3 = 0.18 are satisfied.

Further, in the thinned optical lens set for photographing of the third embodiment of the present invention, the angle corresponding to the main beam incident electro-sensitive element (Chief Ray Angle) of the imaging height is CRA, and half of the maximum viewing angle is HFOV. Then, the condition (tan (CRA)) / (tan (HFOV)) = 0.66 is satisfied.

In the thin-type optical lens set for photographing according to the third embodiment of the present invention, an object to be photographed in the thin-type optical lens set for photographing is imaged on an electro-sensitive element, and the thin-type optical lens set for photographing is optical. If the total length is TTL and the imaging height of the thin optical lens set for shooting is ImgH, the condition of TTL / ImgH = 2.42 is satisfied.

Detailed data of the structure of the third embodiment of the present invention is shown in Table 5, the aspherical data is shown in Table 6, the unit of curvature radius, thickness and focal length is mm, HFOV is the maximum viewing angle Defined as half of

Further, what is desired to be described is a change table of different numerical values of the embodiments of the thinned optical lens set for photographing shown in Tables 1 to 6, but all the numerical values of the respective embodiments of the present invention are changed. Even if data obtained by experiments and using different numerical values, products having the same structure still belong to the claims of the present invention. Table 7 shows data corresponding to the related equations of the present invention in each example.

It is the schematic of the optical system of the 1st Example of this invention. It is an astigmatism curve figure of the 1st example of the present invention. It is the schematic of the optical system of the 2nd Example of this invention. It is an astigmatism curve figure of the 2nd example of the present invention. It is the schematic of the optical system of the 3rd Example of this invention. It is an astigmatism curve figure of the 3rd example of the present invention.

Explanation of symbols

10 First lens
11 Front
12 Rear
20 Second lens
21 Front
22 Rear
30 Third lens
31 Front
32 Rear
40 Aperture of thin optical lens set for photography
50 Infrared filter
60 Image plane
V1 1st lens Abbe number
V2 2nd lens Abbe number
V3 3rd lens Abbe number
N1 1st lens refractive index
N3 Third lens refractive index
f1 First lens focal length
f2 Second lens focal length
f3 Third lens focal length
f Focal length of thin optical lens set for shooting
R1 first lens front radius of curvature
R2 Back radius of curvature of the first lens
R3 second lens front radius of curvature
R4 second lens back radius of curvature
R5 3rd lens front radius of curvature
R6 3rd lens back radius of curvature
ANG32 Mirror surface angle of the third lens back effective radius position
SAG31 Effective diameter height of the front surface of the third lens
CT2 Center thickness of second lens
CT3 Third lens center thickness
T23 Distance between the second and third lenses
Angle corresponding to main light incident electro-sensitive element with CRA imaging height
HFOV half of maximum viewing angle
Total optical length of a thin optical lens set for TTL photography
Imaging height of thin optical lens set for ImgH photography

Claims (21)

A first lens having positive refractive power, a diaphragm, an aspherical second lens having negative refractive power, and a non-negative refractive power having a refractive power, which are arranged in order from the object side to the image side. A third lens having a spherical surface, and the first lens, the second lens, and the third lens have an aspheric front surface and the first lens, the second lens, and the third lens. The third lens is a resin product, and the first lens has a convex surface on the front surface and the back surface, the second lens has a concave surface on the front surface and a convex surface on the back surface, and the third lens has a front surface. Is a thin optical lens set for photographing, in which is a convex surface, a back surface is concave, and the third lens is provided with an inflection point. When the Abbe number of the first lens is V1, the Abbe number of the second lens is V2, and the Abbe number of the third lens is V3, the condition of (V1 + V3) / 2−V2> 20 is satisfied. 2. The thin optical lens set for photographing according to claim 1, wherein the optical lens set is satisfactory. 3. The condition of 1.3 <f / fl <1.7 is satisfied, where f is a focal length of the first lens and f is a focal length of the entire thin optical lens set for photographing. A thin optical lens set for photographing described in 1. The condition of -0.5 <f / f2 <0 is satisfied, where f2 is a focal length of the second lens and f is a focal length of the entire thin optical lens set for photographing. 3. A thin optical lens set for photographing according to 3. The condition of -0.4 <f / f3 <0 is satisfied, where f3 is a focal length of the third lens and f is a focal length of the entire thin optical lens set for photographing. 4. A thin optical lens set for photographing according to 4. If the distance between the second lens and the third lens is T23, and the thickness of the center of the third lens is CT3, the condition of T23 / CT3 <0.3 is satisfied, The thin optical lens set for photographing according to claim 1. If the focal length of the first lens is fl, the focal length of the second lens is f2, the focal length of the third lens is f3, and the focal length of the entire thinned optical lens set for shooting is f,
The thinning for photography according to claim 6, wherein the three conditions of 1.35 <f / fl <1.5, -0.3 <f / f2 <0, and -0.2 <f / f3 <0 are satisfied. Optical lens set. When the curvature radius of the front surface of the first lens is Rl and the curvature radius of the back surface of the first lens is R2, the condition of -0.9 <R1 / R2 <-0.1 is satisfied. Item 7. A thin optical lens set for photographing according to item 6. 9. The condition of 0.4 <R3 / R4 <1.0 is satisfied if the curvature radius of the front surface of the second lens is R3 and the curvature radius of the back surface of the second lens is R4. A thin optical lens set for photographing described in 1. 10. The condition of 0.6 <R5 / R6 <1.6 is satisfied, where R5 is a curvature radius of the front surface of the third lens and R6 is a curvature radius of the back surface of the third lens. A thin optical lens set for photographing described in 1. The curvature radius of the front surface of the first lens is R1, the curvature radius of the back surface of the first lens is R2, the curvature radius of the front surface of the second lens is R3, and the curvature radius of the back surface of the second lens is R4. If the radius of curvature of the front surface of the third lens is R5 and the radius of curvature of the back surface of the third lens is R6, -0.8 <R1 / R2 <-0.5, 0.55 <R3 / R4 <0.85, and 0.9 11. The thin-type optical lens set for photographing according to claim 10, wherein three conditions of <R5 / R6 <1.4 are satisfied. If the refractive index of the first lens is N1, and the refractive index of the third lens is N3,
3. The thin optical lens set for photographing according to claim 2, wherein the conditions of 1.54 <N1 <1.6 and 1.5 <N3 <1.6 are satisfied. The object to be photographed with the thin optical lens set for photographing forms an image on an electro-sensitive element, and the total optical length of the thin optical lens set for photographing is TTL, and the imaging height of the thin optical lens set for photographing is set to TTL. 2. The thin-type optical lens assembly for photographing according to claim 1, wherein if ImgH, the condition of TTL / ImgH <2.65 is satisfied. 2. The thin optical lens set for photographing according to claim 1, wherein the first lens is a glass product. If the distance between the second lens and the third lens is T23, and the thickness of the center of the third lens is CT3, the condition of T23 / CT3 <0.3 is satisfied, The thin optical lens set for photographing according to claim 1. The angle (Chief Ray Angle) corresponding to the main beam incident electro-sensitive element of the imaging height is CRA,
3. The thin-type optical lens set for photographing according to claim 2, wherein the condition of 0.45 <tan (CRA) / tan (HFOV) <1.15 is satisfied if half of the maximum viewing angle is HFOV. 3. The thin-type optical lens set for photographing according to claim 2, wherein a condition of ANG32 <−10 degrees is satisfied if a mirror surface angle at a back effective radius position of the third lens is ANG32. The distance between the second lens and the third lens is T23, and if the thickness of the center of the third lens is CT3, the condition of T23 / CT3 <0.25 is satisfied, 16. A thin optical lens set for photographing according to claim 15. If the distance between the second lens and the third lens is T23, and the thickness of the center of the third lens is CT3, the conditions of T23 / CT3 <0.25 and T23 <0.15 (mm) are satisfied. 6. The thin-type optical lens set for photographing according to claim 5, which satisfies the above. 2. The thin-type optical lens set for photographing according to claim 1, wherein if the height of the effective diameter of the front surface of the third lens is SAG31, the condition of SAG31 <0.2 (mm) is satisfied. The distance between the second lens and the third lens is T23, and if the thickness of the center of the second lens is CT2, the condition of T23 / CT2 <0.3 is satisfied, The thin optical lens set for photographing according to claim 1.

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