KR20150138755A - Iris recognition lens - Google Patents

Abstract

The present invention relates to a lens to be applied to a camera for iris recognition using near-infrared light including a material to block visible light and, more specifically, relates to a photographing lens comprising: a first lens in the form of a meniscus having positive refractive power, whose surface toward an object is convex; an aperture; a second lens in the form of a meniscus having a negative refractive power, and whose surface of the upper side is concave; and a third lens having a negative refractive power, having an aspherical surface wherein at least one between a surface toward an object or a surface of the upper side includes an inflection point, and the conditions of 820 nm<λ<980 nm and ¦f1¦<¦f2¦<¦f3¦ satisfied. Here, λ is a wavelength of light wherein a lens for iris recognition is operated; f1 is a first lens focal distance; and f2 and f3 are second lens and third lens focal distances respectively, thus being small and having a high resolution to be applied to a smartphone or a tablet PC. Moreover, as the lens includes a visible light absorber, a filter to blow visible light is not used, and the manufacturing costs saved by reducing the number of components.

Description

{IRIS RECOGNITION LENS}

The present invention is applicable to an iris recognition camera using near-infrared illumination including a material for blocking visible light. More specifically, the present invention relates to an image pickup lens, which comprises a first lens having a meniscus shape having a positive refractive power from the object side and a convex surface facing the object side, a diaphragm, a second lens having a meniscus shape with a concave upper surface, At least one of the object side and the image side having a refractive power includes an aspherical surface including an inflection point, and the following condition is satisfied.

820 nm <? &Lt; 980 nm - (1)

| f1 | <| f2 | <| f3 | ------------- (2)

Here,? Is the wavelength of the light that the iris recognition lens of the present invention operates, f1 is the focal length of the first lens, and f2 and f3 are the focal lengths of the second lens and the third lens, respectively.

Therefore, it is compact and has high resolution so that it can be applied to smartphone or tablet PC.

Further, since the lens itself includes a visible light absorbing agent, a filter for blocking visible light may not be used, so that the number of parts can be reduced and the production cost can be reduced.

Recently, the importance of security has been emphasized as more and more people use smart phones or mobile terminals to handle important information related to personal information and financial transactions including photographs.

Conventionally, a user has used a method of inputting a password or inputting a fingerprint. However, as a series of personal information leakage events have occurred, a method of approving important information of a smart phone or a portable terminal or approving a financial transaction has been simplified It is urgent to develop a personal recognition technology that is difficult to duplicate.

Recently, iris recognition technology using an individual iris pattern has been introduced. Unlike fingerprints, iris recognition has an advantage in that it can be photographed using a camera in a noncontact manner, and human iris can be a powerful personal recognition technology because it has a unique pattern for each individual.

However, in order to apply iris recognition technology to a smart phone or a portable terminal, a miniaturized camera lens that operates under near-infrared illumination and acquires a small range of images at a short distance is needed.

A camera lens mounted on a conventional smart phone is disclosed in US Pat. No. 7,375,903. Since the camera lens is mainly used for background or portrait photographing, the eye of a person is obtained as a very small image for iris recognition because the field of view is large. It is difficult to process the program used, and the wavelength of the light that operates the camera lens is visible light, which makes shooting difficult in a dark place such as a room.

Therefore, if the camera lens can be mounted on a smart phone or a portable terminal by reducing the angle of view and miniaturizing the camera lens so that only a part of a person's eye in a short distance can be acquired under infrared illumination, the iris recognition technology can be popularized.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems,

SUMMARY OF THE INVENTION It is an object of the present invention to provide an iris recognition lens which can cope with near-infrared illumination used for iris recognition by allowing a wavelength of light to be operated by a lens to be located in a wavelength range of near-infrared rays.

Another object of the present invention is to shorten the focal length of the first lens positioned closest to the object side to increase the refractive power to shorten the overall length of the iris recognition lens, And to provide an iris recognition lens which can be obtained as an image.

It is still another object of the present invention to provide an iris recognition lens in which spherical aberration, astigmatism, and distortion aberration are satisfactorily corrected while the curved surface of the lens is an aspherical surface, and which is advantageous for miniaturization.

It is still another object of the present invention to increase the amount of near infrared rays entering the first lens by increasing the thickness of the first lens and increasing the incident angle of the lens by positioning the diaphragm between the first lens and the second lens, An iris recognition lens capable of acquiring a clear image is provided.

It is a further object of the present invention to provide an eyepiece lens for an iris which is advantageous in downsizing and has a small number of parts and a low production cost because it does not need a separate visible light shielding filter by including a visible light absorbing agent in the lens itself.

It is still another object of the present invention to provide an iris recognition lens which is made of a plastic material so as to facilitate the addition of the visible light absorbing agent.

The iris recognition lens for achieving the object of the present invention includes the following configuration.

An iris recognition lens according to an embodiment of the present invention includes a lens group for refracting near infrared rays reflected by an iris to cause an image to be formed on an image plane, a diaphragm for adjusting the amount of near-infrared rays incident on the lens group, The lens group includes a first lens, a second lens and a third lens which are arranged in order from the object side, and is miniaturized, and the angle of view is narrow, and only the iris region is imaged And the like.

According to another embodiment of the present invention, in the iris recognition lens according to the present invention, the first lens is a convex meniscus lens having a positive refractive power, and the second lens is a concave meniscus lens having a negative refractive power, And the third lens is a concave meniscus lens having a negative refractive power.

According to another embodiment of the present invention, the iris recognition lens according to the present invention is characterized in that at least one of the object side surface or the image side surface of the first lens, the second lens, and the third lens is aspherical.

According to another embodiment of the present invention, the iris recognition lens according to the present invention is characterized in that the diaphragm is positioned between the first lens and the second lens and the first lens positioned in front of the diaphragm is made thicker than the second lens And the amount of near-infrared rays incident on the lens group is increased by increasing the incident angle of the lens.

According to another embodiment of the present invention, the iris recognition lens according to the present invention is characterized in that it can operate under the wavelength of near infrared rays satisfying the following conditions.

820 nm <? &Lt; 980 nm

Here,? Is the wavelength of light in which the iris recognition lens operates.

According to another embodiment of the present invention, the iris recognition lens according to the present invention is characterized in that only the iris region can be obtained as an image because the angle of view is narrowed while being miniaturized by satisfying the following conditions.

| f1 | <| f2 | <| f3 |

Here, f1 is the focal length of the first lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

According to another embodiment of the present invention, in the iris recognition lens according to the present invention, the lens group includes a visible ray absorbent and is advantageous for miniaturization because it does not need to use a visible ray filter.

According to another embodiment of the present invention, in the iris-detecting lens according to the present invention, the lens group is a lens made of plastic, so that it is easy to include the visible ray absorbing agent.

According to another embodiment of the present invention, in the iris recognition lens according to the present invention, the first lens has a curvature radius of 0.9195 mm on the object side, a curvature radius on the upper side of 1.6103 mm, and a thickness of 1.0300 mm .

According to another embodiment of the present invention, in the iris recognition lens according to the present invention, the refractive index of the first lens is 1.51520 and the dispersion value is 56.6.

According to another embodiment of the present invention, in the iris recognition lens according to the present invention, the second lens has a curvature radius of 1.3955 mm on the object side, a curvature radius on the upper side of 0.9337 mm, and a thickness of 0.3000 mm .

According to another embodiment of the present invention, in the iris recognition lens according to the present invention, the refractive index of the second lens is 1.51520 and the dispersion value is 56.6.

According to another embodiment of the present invention, in the iris recognition lens according to the present invention, the third lens has a radius of curvature of 1.9742 mm on the object side, a radius of curvature of 1.6682 mm on the upper side, and a thickness of 0.3000 mm .

According to another embodiment of the present invention, in the iris recognition lens according to the present invention, the refractive index of the third lens is 1.51520 and the dispersion value is 56.6.

The present invention can obtain the following effects by the above-described embodiment, the constitution described below, the combination, and the use relationship.

The present invention has the effect of providing an iris recognition lens capable of coping with near-infrared illumination used for iris recognition by allowing the wavelength of light in which the lens operates to be located in the wavelength range of near-infrared rays.

In the present invention, by shortening the focal length of the first lens located closest to the object side and increasing the refractive power, the entire length of the iris recognition lens is shortened, but the focal length is lengthened to reduce the angle of view, There is provided an effect of providing an iris recognition lens which can be used.

The present invention has an effect of providing an iris recognition lens in which spherical aberration, astigmatism, and distortion aberration are satisfactorily corrected while the curved surface of the lens is an aspherical surface, and which is advantageous for miniaturization.

The present invention increases the amount of near infrared rays entering the first lens by increasing the thickness of the first lens and increasing the incident angle of the lens by positioning the diaphragm between the first lens and the second lens to obtain a clear image even in a dark environment There is provided an effect of providing an iris recognition lens which can be used.

The present invention has an effect of providing an iris-edifying lens which is advantageous in downsizing and has a small number of parts and a low production cost because it does not need to include a visible light blocking filter by including a visible ray absorbing agent in the lens itself.

INDUSTRIAL APPLICABILITY The present invention has an effect of providing an iris recognition lens which is made of a plastic material so as to facilitate the addition of the visible light absorbing agent.

1 is a side sectional view showing a configuration of an iris recognition lens of the present invention.
2 is an optical path diagram when near infrared rays are incident on the iris recognition lens of the present invention.
3 is a reference view for explaining the focal length of the lens group of the iris recognition lens of the present invention.
4 is a graph showing spherical aberration, astigmatism, and distortion aberration of the iris recognition lens of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments of the present invention can be modified in various forms, and the scope of the present invention should not be construed as being limited to the following embodiments. This embodiment is provided to more fully describe the present invention to those skilled in the art. Thus, the shape of the elements in the figures has been exaggerated to emphasize a clearer description.

In the present invention, the light ray travels from left to right in parallel with the optical axis Z and enters the lens. On the basis of the iris recognition lens 1, the left side is the object side on which the object exists and the right side is the upper side .

Hereinafter, an iris recognition lens 1 according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the iris recognition lens 1 includes a lens group 10 that operates under near-infrared light, a miniature lens group 10, a diaphragm 30 that adjusts the amount of near-infrared rays incident on the lens group 10, And an image forming surface 50 that forms an image by the near-infrared ray passing through the group 10.

2, in order to acquire an image of an iris, near-infrared rays corresponding to image information of a subject include first, second, and third lenses 11, 12, 13, 15 and is incident on the imaging plane 50.

The near-infrared rays are refracted through the lens group 10 of the iris recognition lens 1. In the present invention, the force that the lens refracts the light ray is defined as the refracting power. Generally, the refractive power is determined by the curvature of the front and back surfaces of the lens, the refractive index of the lens, etc. The exact numerical value of the refractive power can be calculated by a known mathematical expression or the like.

The refractive power is divided into a positive refractive power and a negative refractive power. The lens having positive refractive power moves in parallel with the ground to refract to converge the light rays passing through the lens. The lens having negative refractive power moves in parallel with the ground, Refract to radiate light.

1, the lens group 10 is a group of lenses including a first lens 11, a second lens 13 and a third lens 15 which are arranged in order from the object side , Refracts near infrared rays reflected from irises reflected from the illumination provided in a smart phone, a portable terminal, or the like to cause the image plane 50 to form an image.

The first lens 11 includes an object side surface S1 and an upper surface S2 and has a positive refractive power and has a convex meniscus shape on the object side in the vicinity of the optical axis Z, .

The second lens 13 includes an object side surface S4 and an upper side surface S5 and has a negative refractive power and has a concave meniscus shape on the image side in the vicinity of the optical axis Z and a concave meniscus lens .

The third lens 15 has an object side surface S6 and an upper side surface S7 and has a negative refractive power and has a concave meniscus shape on the image side in the vicinity of the optical axis Z and a concave meniscus lens .

The meniscus shape means a lens in which a curved surface is machined in the same direction as a crescent moon, and the meniscus lens having a thicker center portion than the peripheral portion is called a convex meniscus lens, The meniscus lens having a thinner thickness than the peripheral portion is called a concave meniscus lens.

The convex meniscus lens has a positive refractive power because it performs a light converging action, and the concave meniscus lens has a negative refractive power because it performs a diverging action.

2, the near-infrared rays passing through the first lens 11 are converged by the positive refractive power of the first lens 11. Therefore, the near-infrared rays passing through the first lens 11 are converged by the positive refractive power of the first lens 11, The near-infrared rays passing through the first lens 11 pass through the second lens 13 having a negative refracting power so that the optical path around the center of the second lens 13 By shortening the focus difference between the center and periphery of the image is reduced.

At least one of the object side surfaces S1, S4, S6 and the upper side surfaces S2, S5, S7 of the first lens 11, the second lens 13 or the third lens 15, It is made of aspherical surface as specified, and it is possible to correct the aberration effectively with a small number of lenses of three lenses.

The lens is divided into a spherical lens and an aspheric lens. The aspherical lens has a different dimension (for example, a two-dimensional curve, a three-dimensional curve) of the curvature of the lens surface, which is different from the spherical lens. The aberration correction through the aspherical lens is equivalent to the known art, and therefore, a detailed description thereof will be omitted.

The third lens 15 has negative refracting power but has almost no refracting power, so that the fine adjustment of the focus of the center and periphery of the image can be performed to obtain a high resolution image.

The lens group 10 includes a visible light absorbing material. The conventional infrared lens has disadvantages in that it is disadvantageous in downsizing since a filter for shielding visible light is required between the lens and the sensor. Therefore, the present invention includes a visible light absorbing material in the lens group 10 itself, And reduce the number of parts to lower the production cost.

Since the lens group 10 includes a visible light absorbing material, it transmits near infrared rays and absorbs or reflects visible rays.

The lens group 10 may be made of a plastic material. Therefore, it is easy to add the visible light absorbing agent. However, it is not limited to this and may be made using other materials.

The diaphragm 30 is positioned between the upper surface S2 of the first lens 11 and the object side surface S4 of the second lens 13 and has a predetermined shape but is preferably a thin plate, And is formed so as to open or tighten an empty space inside as in a general diaphragm 30 to adjust the amount of near-infrared rays entering the lens.

Since the diaphragm 30 has a vignetting effect for shielding a light beam that blurs the focus of the peripheral portion of the image, the peripheral portion of the image formed on the image forming surface 50 is sharpened.

Since the diaphragm 30 is located between the first lens 11 and the second lens 13 and can increase the incident angle of the lens with respect to the front of the first lens 11, It is possible to increase the amount of near-infrared rays entering the edible lens 1.

The entrance pupil of the lens is an aperture diaphragm of the virtual image seen when the lens is viewed from the object side. In the present invention, the aperture diaphragm A is from A to A 'shown in FIG. 2 If the entrance pupil is located in front of the lens 1, the entrance pupil becomes a diameter of B to B '.) If the entrance pupil is increased, the amount of near infrared rays entering the lens is increased.

The first lens 11 is thicker than the second lens 13 and the third lens 15 and has a larger thickness than the first lens 11, Since the aperture from A to A 'is larger than when it is thin, it can increase the amount of near infrared rays coming into the lens.

The image plane 50 may include an image sensor such as a CCD or a CMOS for converting an optical signal corresponding to an object image into an electrical signal, where the image of the iris is formed.

The iris recognition lens 1 preferably satisfies the following conditional expression.

820 nm <? &Lt; 980 nm - (1)

| f1 | <| f2 | <| f3 | ------------- (2)

Where f1 is the focal length of the first lens 11, f2 is the focal length of the second lens 13, f3 is the focal length of the first lens 11, Is the focal length of the third lens (15).

[Conditional expression 1] represents the wavelength range of light in which the iris recognition lens 1 operates. Generally, infrared rays have a range of 800 nm to 4000 nm. Therefore, when the iris recognition lens 1 satisfies the condition (1), it becomes possible to cope with near-infrared illumination used for iris recognition.

[Conditional expression 2] represents the correlation of the focal length absolute values of the lens group 10. The shorter the focal length of the first lens 11 positioned closest to the object side is, the larger the refracting power is. Therefore, the entire length of the lens group 10 of the iris recognition lens 1 is shortened, By reducing the angle of view (the focal distance and the angle of view are inversely proportional), only the iris region of the person can be acquired with the image.

In general, the focal length of the lens group means the distance from the second principal point to the image-forming plane formed with the image. If the second principal point has a virtual lens in one piece serving as the lens group, . When the water line is intersected with the optical axis at a point where a line that extends the locus of the light beam entering the lens group and a line that extends the locus of the light beam that intersects the optical axis intersect each other.

3, the second principal point of the iris recognition lens 1 includes a line C 'extending a locus of a light ray entering the point C of the first lens 11, Point E intersects with the optical axis Z when a waterline is drawn from the intersection E 'of the line D' extending the trajectory of the light ray exiting to the point D of the optical axis 15 to the optical axis Z. [ Therefore, the focal distance of the iris recognition lens 1 is the distance from the E point to the image plane 50. [

Generally, the focal length of the lens can not be greater than the distance from the lens to the image plane 50, since it is the distance from the center of the lens to the place where the image is formed (the place where the rays gather). Therefore, the focal length when the first lens 11, the second lens 13, or the third lens 15 is used alone can not be larger than the distance from the lenses to the image-forming surface 50. However, the lens group 10 satisfying the above-mentioned [Conditional Expression 2] of the iris recognition lens 1 has a focal length longer than the focal length when the lenses 11, 13, and 15 are used alone . Therefore, the entire length of the iris recognition lens 1 does not increase so much that it is not burdened in miniaturization, and since the focal length is long and the angle of view is narrow, only the human iris region can be acquired as an image.

Optical data of the iris recognition lens 1 according to the present embodiment is shown in Table 1.

The surface number (Si) Curvature radius (Ri) The surface interval Di Refractive index (Ndi) The dispersion value (vdi) Remarks S1 * 0.9195 1.0300 1.51520 56.6 S2 * 1.6103 0.1500 S3 ∞ 0.0800 iris S4 * 1.3955 0.3000 1.51520 56.6 S5 * 0.9337 0.1325 S6 * 1.9742 0.3000 1.51520 56.6 S7 * 1.6682 1.0066 S8 ∞ Image plane

The * mark indicates an aspherical surface

In the embodiment of Table 1, the focal length f of the lens group 10 is 3.10 mm, the aperture value F is 2.23, and the angle of view is 11.3 degrees.

As shown in FIG. 1, the surface number Si is set so that the surface of the component located closest to the object side as shown in FIG. 1 becomes the first surface, Represents the number of the i-th surface attached.

The curvature radius Ri represents the value of the radius of curvature of the i-th surface on the object side corresponding to the surface number Si. The unit is mm. If Si is an aspheric surface, its radius of curvature indicates the value of the radius of curvature in the vicinity of the optical axis (Z).

The surface interval Di represents an interval on the optical axis Z between the i-th surface and the (i + 1) -th surface on the object side corresponding to the surface number Si. The unit is mm.

The refractive index Ndi and the dispersion value vdi are set such that the refractive index and dispersion value of the first lens 11, the second lens 13 and the third lens 15, except for the diaphragm 30 and the imaging plane 50, (Abbe number).

Table 2 shows the aspherical surface coefficients of the iris recognition lens 1 according to the present embodiment with respect to the aspheric lens.

Face number k A4 A6 A8 A10 One -0.708891 0.833842E-01 0.646217E-01 -0.278508E-02 0.713688E-01 2 5.720564 0.971435E-01 -0.670672E + 00 -0.861678E-01 -0.555072E + 01 4 0.000000 0.174146E + 00 -0.128384E + 01 -0.421345E + 01 -0.534481E + 01 5 0.000000 -0.189225E + 00 -0.130559E + 01 -0.207623E + 02 0.324363E + 02 6 -33.118738 -0.836381E + 00 -0.397346E + 01 0.881438E + 00 -0.545603E + 00 7 0.000000 -0.913283E + 00 -0.951808E + 00 0.958740E + 01 -0.147232E + 02

The aspherical surface coefficient values of the aspherical surface lens of Table 2 can be obtained from the following Equation 1, which is an aspherical equation.

Here, z represents a distance from a coordinate point on the aspheric surface having a height h from the optical axis Z to a tangent line (a line perpendicular to the optical axis Z) at an aspheric surface apex.

K is the conic constant, c is the lens curvature at the aspheric apex, and is the reciprocal of the radius of curvature, and A4, A6, A8, A10, etc. represent aspheric coefficients.

That is, the first lens 11, the second lens 13, and the third lens 15 include aspherical surfaces having the above-mentioned aspherical surface coefficient values, and through this, spherical aberration, astigmatism, and distortion aberration can be corrected have.

4 shows the spherical aberration a, the astigmatism b, and the distortion aberration c according to the embodiment of the present invention, respectively.

Wherein the spherical aberration represents a spherical aberration according to a near infrared ray (? = 820, 850, 880 nm), the astigmatism represents aberration characteristics of a tangential plane and a sagittal plane according to a height of an image, .

As shown in FIG. 4, since the values of the aberrations in all aberrations appear adjacent to the axis, it can be seen that the iris recognition lens 1 according to the embodiment of the present invention has excellent aberration characteristics.

The calculated values according to [Conditional Expression 2] of the iris recognition lens 1 according to the present embodiment are shown in Table 3.

Conditional expression (2) Example | f1 | <| f2 | <| f3 | 2.82 < 7.14 < 31.77

The absolute value of the focal length of the first lens 11 is 2.82, the absolute value of the focal length of the second lens 13 is 7.14, and the absolute value of the focal length of the third lens 15 is 31.77 The condition (2) is satisfied.

Applicants explain the working relationship of the present embodiment in the following.

The iris recognition lens 1 includes the lens group 10, the diaphragm 30, and the imaging plane 50. Since the visible light absorbing agent is added to the lens group 10 while satisfying conditional expression 1, the lens group 10 receives the near infrared rays reflected from the iris and emits the unnecessary visible rays incident along with the near infrared rays. So that a clear iris image can be obtained.

The near-infrared rays pass through the first lens 11 having a positive refractive power and are incident on the second lens 13 via the diaphragm 30.

Since the first lens 11 is designed to satisfy the condition (2), the absolute value of the focal length is smaller than that of the second lens 13 and the third lens 15, and thus has a high positive refractive power. Therefore, by reducing the angle of view by lengthening the focal length while reducing the diameter of the edible lens 1, it is possible to acquire only the human iris region as an image.

The diaphragm 30 is located between the first lens 11 and the second lens 13 and increases the entrance pupil of the lens by making the first lens 11 thick, By increasing the amount of incoming light, a clear iris image can be obtained even in a dark environment.

Since the diaphragm 30 has a vignetting effect for shielding a light beam that blurs the focus of the peripheral portion of the image, the peripheral portion of the image formed on the image forming surface 50 is sharpened.

The near-infrared rays pass through the second lens 13 having a relatively high negative refractive power and are incident on the third lens 15.

Since the near-infrared ray passing through the first lens 11 has a positive refractive power, the optical path around the center of the first lens 11 becomes long, and the focus of the image may be blurred. The near infrared ray passing through the first lens 11 is allowed to pass through the second lens 13 having a negative refractive power to shorten the optical path around the center of the second lens 13, Reduce the focus difference between the center and periphery of the image by matching the near-infrared rays passing through and the near-infrared rays passing through the periphery in a similar manner.

Since the third lens 15 has little refractive power, the near-infrared rays are only slightly refracted and are incident on the imaging plane 50 to acquire images of the iris.

Since the third lens 15 includes an aspherical surface including an inflection point, it is possible to acquire a sharp image with a fine focus.

The first lens 11, the second lens 13, and the third lens 15 are aspherical surfaces, the aberration correction can be effectively performed with a small number of lenses of three lenses, which is advantageous for miniaturization.

The foregoing detailed description is illustrative of the present invention. In addition, the foregoing is intended to illustrate and explain the preferred embodiments of the present invention, and the present invention may be used in various other combinations, modifications, and environments. That is, it is possible to make changes or modifications within the scope of the concept of the invention disclosed in this specification, within the scope of the disclosure, and / or within the skill and knowledge of the art. The embodiments described herein are intended to illustrate the best mode for implementing the technical idea of the present invention and various modifications required for specific applications and uses of the present invention are also possible. Accordingly, the detailed description of the invention is not intended to limit the invention to the disclosed embodiments. It is also to be understood that the appended claims are intended to cover further embodiments.

1: iris recognition lens
10: Lens group
11: first lens 13: second lens 15: third lens
30: aperture stop 50: imaging surface Z: optical axis
Si: an i-th lens surface on the object side
Ri is the radius of curvature of the i-th lens surface on the object side
Di: the surface interval between the i-th lens and the (i + 1) -th lens surface on the object side

Claims (14)

An iris for refracting the near infrared rays incident on the iris to cause an image to be formed on the image plane, an iris for adjusting the amount of near infrared rays incident on the lens group, and an image forming surface formed by the near- and,
Wherein the lens group includes a first lens, a second lens, and a third lens that are positioned in order from the object side, and is miniaturized while narrowing the angle of view, so that only the iris region can be obtained as an image. The method according to claim 1,
The first lens is a convex meniscus lens having a positive refractive power,
The second lens is a concave meniscus lens having a negative refractive power,
And the third lens is a concave meniscus lens having a negative refractive power. 3. The method of claim 2,
Wherein at least one of an object-side surface and an image-side surface of the first lens, the second lens, and the third lens is an aspherical surface. 3. The method of claim 2,
The diaphragm is positioned between the first lens and the second lens and the first lens positioned in front of the diaphragm is made thicker than the second lens to increase the incident angle of the lens to increase the amount of near- And a second lens group. The method according to claim 1,
Wherein the iris recognition lens satisfies the following conditions and is capable of operating under the wavelength of near infrared rays.
820 nm &lt;?&Lt; 980 nm
Here,? Is the wavelength of light in which the iris recognition lens operates. 6. The method of claim 5,
[6] The iris recognition lens according to claim 4, wherein the iris recognition lens satisfies the following conditions and is miniaturized, but has a narrow angle of view and can acquire only an iris region as an image.
| f1 | <| f2 | <| f3 |
Here, f1 is the focal length of the first lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens. 7. The lens assembly according to any one of claims 1 to 6, wherein the lens group comprises a visible light absorbing agent,
An iris recognition lens which is advantageous in miniaturization since it does not need to use a visible light filter. 8. The iris recognition lens according to claim 7, wherein the lens group is a lens made of a plastic material, so that it is easy to include the visible light absorbing agent. 7. The method according to any one of claims 1 to 6,
Wherein the first lens has a curvature radius of the object side of 0.9195 mm, a curvature radius of the upper surface of 1.6103 mm, and a thickness of 1.0300 mm. The iris recognition lens according to claim 9, wherein the refractive index of the first lens is 1.51520 and the dispersion value is 56.6. 11. The method of claim 10,
Wherein the second lens has a curvature radius of 1.3955 mm on the object side, a curvature radius on the upper side of 0.9337 mm, and a thickness of 0.3000 mm. 12. The iris recognition lens according to claim 11, wherein the refractive index of the second lens is 1.51520 and the dispersion value is 56.6. 13. The method of claim 12,
Wherein the third lens has a curvature radius of 1.9742 mm on the object side, a curvature radius on the upper side of 1.6682 mm, and a thickness of 0.3000 mm. 14. The method of claim 13,
Wherein the refractive index of the third lens is 1.51520 and the dispersion value is 56.6.

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