KR102570047B1 - Image pickup lens, camera module and digital device including the same - Google Patents

Abstract

An embodiment includes first to fourth lenses sequentially arranged from an object side to an imaging side, wherein the first lens has negative refractive power, and the second lens and the third lens have positive refractive power. and the fourth lens has negative refractive power and satisfies Equation 1.
<Equation 1>
-40.0 < R1+R2 < -25.0, where R1 is the radius of curvature of the object surface of the first lens, and R2 is the radius of curvature of the imaging surface of the first lens.

Description

Imaging lens, camera module and digital device including the same

The embodiment relates to an imaging lens.

In general, an optical system employed in a vehicle camera or surveillance camera requires a wide-angle lens having a wide angle of view with a horizontal angle of view of more than a certain angle in order to capture a wider range of images of the front, side and rear lights, and the lens employed in the optical system at the same time. There is a demand for miniaturization and weight reduction.

In this trend, miniaturization of a light receiving device such as a CCD (Charge Coupled Device) mounted in a miniaturized imaging device is progressing, but the most bulky part of the imaging device is the imaging lens part.

Accordingly, the most important component for miniaturization and thinning of the imaging device is an imaging lens that forms an image of an object.

However, in the case of implementing an optical system having a wide angle of view, the optical axis direction length of the optical system is long, and the diameter of the lens must be increased to secure the amount of peripheral light, which acts as a factor hindering the compactness of the optical system.

Embodiments are intended to provide an imaging lens having high performance and ultra-thin size.

An embodiment includes first to fourth lenses sequentially arranged from an object side to an imaging side, wherein the first lens has negative refractive power, and the second lens and the third lens have positive refractive power. and the fourth lens has negative refractive power and satisfies Equation 1.

<Equation 1>

-40.0 < R1+R2 < -25.0, where R1 is the radius of curvature of the object surface of the first lens, and R2 is the radius of curvature of the imaging surface of the first lens.

For example, the refractive index of the third lens may be greater than 1.57 and less than 1.60.

For example, the Abbe number of the third lens may be greater than 60 and less than 64.

For example, the conic constant of the object surface of the third lens may be greater than -0.10 and less than 0.21, and the conic constant of the image plane of the third lens may be greater than -1.4 and less than -0.7. there is.

For example, a diaphragm disposed between the second lens and the third lens may be further included.

For example, at least one of the first to fourth lenses may be made of glass.

Another embodiment includes first to fourth lenses sequentially disposed in a direction from an object side to an imaging side, wherein the first lens has a concave object surface and has negative refractive power, and the second lens has a positive refractive power, the third lens is made of glass and has a positive refractive power, and the fourth lens is made of plastic and has a negative refractive power and is disposed between adjacent lenses, an imaging lens comprising a gap maintaining member maintaining a gap between the lenses, wherein the gap maintaining member includes a coupling surface including a coupling surface including a plane coupled to an object surface and an imaging surface of the neighboring lenses, respectively. provides

For example, the gap maintaining member may have a diffuse reflection preventing portion formed on an inner circumferential surface.

For example, at least one contact surface coupled to a coupling surface of the gap maintaining member may be included in the target surface and/or the imaging surface of the first to fourth lenses, and at least a portion of the contact surface may be flat.

For example, the anti-radiation portion of the gap maintaining member may include a concave-convex portion.

For example, among the distances between adjacent lenses, the distance between the second lens and the third lens may be the largest.

For example, the aperture of the first lens may be larger than the aperture of the second lens, and the aperture of the second lens may be larger than the aperture of the third lens.

Another embodiment is a housing; and the above-described imaging lens disposed within the housing.

Another embodiment provides a digital device including the camera module described above.

The imaging lens according to the embodiment can implement a low-distortion image with a wide viewing angle even with four lenses.

1 is a diagram showing a first embodiment of an imaging lens.
Fig. 2 is a diagram showing a second embodiment of an imaging lens.
Fig. 3 is a diagram showing a third embodiment of an imaging lens.
4 is a graph showing an aberration diagram of the first embodiment of an imaging lens, showing longitudinal spherical aberration, astigmatic field curves, and distortion in order from the left.
5 is a graph showing an aberration diagram of a second embodiment of an imaging lens, showing longitudinal spherical aberration, astigmatic field curves, and distortion in order from the left.
Fig. 6 is a graph showing an aberration diagram of a third embodiment of an imaging lens, showing longitudinal spherical aberration, astigmatism, and distortion aberration in order from the left.
7A and 7B are views showing a fourth embodiment of an imaging lens.

Hereinafter, embodiments of the present invention that can specifically realize the above object will be described with reference to the accompanying drawings.

In the description of the embodiments according to the present invention, the 'object surface' refers to the surface of the lens facing the object side with respect to the optical axis, and the 'imaging surface' refers to image formation with respect to the optical axis means the side of the lens facing the image side.

Further, in the present invention, “+ power” of the lens represents a converging lens converging parallel light, and “− power” of the lens represents a diverging lens diverging parallel light.

1 is a diagram showing a first embodiment of an imaging lens, FIG. 2 is a diagram showing a second embodiment of an imaging lens, and FIG. 3 is a diagram showing a third embodiment of an imaging lens.

1 to 3, the first to third embodiments of the imaging lens include a first lens 110, a second lens 120, and a third lens 130 sequentially arranged from the object side to the image side. ) and a fourth lens 140.

And, a shutter may be included on the front of the first lens 110, and an aperture AS may be disposed between the second lens 120 and the third lens 130. It may be a variable aperture.

In addition, the filter 150, the cover glass 160, and the light receiving element 170 are sequentially included to form an imaging lens in the camera module.

Here, a flat optical member such as an infrared ray filter is disposed as the filter 150, and the cover glass 160 may be an optical member, for example, a cover glass for protecting an image pickup surface, and the light receiving element 170 may be an image sensor laminated on a printed circuit board (not shown).

The above-described embodiments and embodiments to be described later may provide an imaging lens that can be applied to a camera module having a high number of pixels and/or pixels, and the above-described camera module includes an image sensor or light-receiving element having a high number of pixels and/or pixels. can do.

1 to 3, 'S11' is the target surface of the first lens 110, 'S12' is the image plane of the first lens 110, 'S21' is the target surface of the second lens 120, 'S22' is the image plane of the second lens 120, 'S31' is the target surface of the third lens 130, 'S32' is the image plane of the third lens 130, and 'S41' is the fourth The target surface of the lens 140 'S42' is an imaging surface of the fourth lens 140.

In embodiments, the first lens 110 may have a concave object surface S11, a flat or concave imaging surface S12, and negative refractive power. Also, the second lens 120 may have a convex target surface S21 and a flat or convex imaging surface S22 and may have positive refractive power. In addition, both the target surface S31 and the imaging surface S32 of the third lens 130 may be convex and have positive refractive power. In addition, both the target surface S41 and the imaging surface S42 of the fourth lens 140 may be concave and may have negative refractive power.

Here, the third lens 130 and the fourth lens 140 are convex to minimize the air gap between the third lens 130 and the fourth lens 140 while being spaced apart from each other at regular intervals. The imaging surface S32 of the lens and the target surface S41 of the fourth lens 140 may be spaced apart from each other by an interval of 40 μm to 60 μm.

The arrangement of the third lens 130 and the fourth lens 140 has an advantage of minimizing aberration by increasing low dispersion performance.

At least one surface of the lenses of the above-described first to fourth lenses 110 to 140 may have an aspheric surface. If at least one surface of the lenses is formed as an aspheric surface, various aberrations, for example, spherical aberration, coma aberration, and distortion It can be excellent for correction of aberrations and the like.

In addition, at least one of the first to fourth lenses 110 to 140 may be made of glass, and since the glass lens has a relatively high transition point, it is possible to minimize deformation of the refractive index and deformation of the focal length even when the temperature changes with time. can

In embodiments, since the third lens 130 into which light passing through the aperture AS is incident is most affected by heat, it may be made of glass.

Here, although all of the first to fourth lenses 110 to 140 may be made of glass, when the lens is made of only glass, the manufacturing cost of the imaging lens is high. As described above, if the third lens is made of glass and the remaining lenses are made of plastic, the cost of manufacturing the imaging lens can be greatly reduced while the imaging lens is minimally affected by heat.

And, the surface of the lens according to the embodiments may be coated to prevent reflection or improve surface hardness.

Meanwhile, the first to third embodiments may satisfy Equation 1 below.

<Equation 1>

-40.0 < R1+R2 < -25.0

Here, R1 is the radius of curvature of the target surface of the first lens, and R2 is the radius of curvature of the imaging surface of the first lens.

In the embodiment, in order to implement a wide-angle lens, the target surface of the first lens may have a concave shape to collect light, and the imaging surface of the first lens may have a concave shape so that the first lens has negative refractive power. .

Here, when the value of R1+R2 is smaller than -40.0 or larger than -25.0, light transmitted through the first lens does not enter the second lens, and a wide angle of view of the imaging lens cannot be secured.

Also, the refractive index of the third lens 130 may be greater than 1.57 and less than 1.60. Here, when the refractive index of the third lens 130 is less than 1.57, the overall length of the imaging lens may be increased, the thickness of the third lens may be increased, and resolution of the imaging lens may be deteriorated. In addition, when the refractive index of the third lens 130 is greater than 1.60, manufacturing of the third lens becomes difficult.

The number of Abbes of the third lens 130 may be greater than 60 and less than 64. If the number of Abbes of the third lens 130 is greater than 60 and less than 64, chromatic aberration of the imaging lens is improved. can be effective in Here, if the number of Abbes of the third lens 130 is less than 60 or greater than 64, it may be difficult to manufacture the third lens.

In addition, the conic constant of the target surface S31 of the third lens 130 may be greater than -0.10 and less than 0.21, and the conic constant of the imaging surface S32 of the third lens 130 may be - It can be greater than 1.4 and less than -0.7. Here, when the conic constant values of the target surface S31 and the imaging surface S32 of the third lens 130 are out of the above range, the resolution may be reduced.

Table 1 shows the radius of curvature, thickness or distance, refractive index and Abbe number of each lens of the first embodiment of the imaging lens.

side number Radius of curvature (R) thickness or distance (d) Refractive Index (Nd) Abbe number (Vd) S11 -36.1944 1.319 1.5311 56.5 S12 2.965159 5.800651 S21 16.36467 2.8 1.5311 56.5 S22 -6.05369 0.460194 AS(stop) 1.00E+18 2.633772 S31 5.246022 2.399853 1.589 61.2 S32 -3.12816 0.05 S41 -3.1766 0.38 1.642 22.4 S42 -97.199 0.983529

In Table 1, the curvatures of the target surface and the imaging surface of the first lens 110, the second lens 120, the aperture (AS), and the third lens 130 and the fourth lens 140 are sequentially described, and the curvature When is positive (+), it is bent toward the object side, and when it is negative (-), it is bent toward the light receiving element. When the curvature is infinite, it is flat, the thickness is described corresponding to each target surface, and the distance to an adjacent lens or the like corresponding to the imaging surface is described.

In the first embodiment, the distance d4 between the imaging plane S22 of the second lens 120 and the aperture AS is 0.460194 mm, and the aperture AS and the target plane S31 of the third lens 130 are The distance d5 between them is 2.633772 mm, and d5 may be smaller than d4. That is, the second lens 120 may be disposed closer to the iris AS than the third lens 130 . This structure is designed so that the third lens 130 is less affected by heat, and a low-distortion image can be obtained by the imaging lens according to the embodiment.

And, by minimizing the air gap between the third lens 130 and the fourth lens 140, the third lens 130 and the fourth lens 140 increase low dispersion performance and minimize aberration. It can be seen that the imaging surface S32 of the third lens 130 and the target surface S41 of the fourth lens 140 may be spaced apart from each other by an interval of 0.05 mm so as to maintain a constant distance while maintaining a constant distance.

In the first embodiment, the refractive power of the first lens 110 is -0.197, the refractive power of the second lens 120 is 0.115, the refractive power of the third lens 130 is 0.270, and the refractive power of the fourth lens 140 is The refractive power is -0.197.

The focal length of the first lens 110 is -5.079, the focal length of the second lens 120 is 8.662, the focal length of the third lens 130 is 3.709, and the focal length of the fourth lens 140 is -5.070. am. Here, when the focal length is +, it means real focus, and when it is -, it means virtual focus, and the same applies to embodiments described below.

Also, the total focal length of the imaging lens according to the first embodiment is 3.1730 mm.

Although not shown, the surface of each lens may be coated to prevent reflection or improve surface hardness.

Table 2 shows the conic constant (k) and aspherical surface coefficients (A to D) of each lens surface in the first embodiment.

side number K A B C D S11 -38.998765 0.212466E-03 -.398223E-05 0.197458E-07 -.706309E-11 S12 -0.493508 0.813849E-03 0.227856E-03 -.203029E-04 0.235975E-05 S21 -40.792050 -.126510E-02 -.408383E-03 0.476455E-04 -.445578E-05 S22 -0.225426 -.192012E-02 -.779158E-04 0.115687E-04 -.126901E-05 S31 0.049368 -.179093E-03 -.850038E-04 0.225443E-04 -.405445E-05 S32 -0.896940 0.276948E-02 0.397754E-03 -.504850E-04 0.248296E-05 S41 -2.358592 -.224844E-02 0.538172E-03 -.279062E-04 0.100786E-05 S42 10.000000 0.393568E-02 -.251601E-03 0.596224E-04 -.404504E-05

It can be seen that both surfaces of the lenses of the first to fourth lenses 110 to 140 are formed in aspheric surfaces. If both surfaces of the lenses of the first to fourth lenses 110 to 140 are formed as aspheric surfaces, it can be excellent in correcting various aberrations, such as spherical aberration, coma aberration, and distortion aberration.

4 is a graph showing an aberration diagram of the first embodiment of an imaging lens, showing longitudinal spherical aberration, astigmatic field curves, and distortion in order from the left.

In FIG. 4 , the Y-axis means the size of an image, the X-axis means the focal length (in mm) and distortion (in %), and as the curves approach the Y-axis, the aberration correction function can be improved. Further, the graph of longitudinal spherical aberration in FIG. 4 shows the longitudinal spherical aberration for light having wavelengths of 435.80 nm, 486.10 nm, 546.10 nm, 587.60 nm, 656.30 nm and 850.00 nm, and the graph of astigmatism shows wavelength of 546.10 nm. Shows aberrations on the sagittal surface (S) and tangential surface (T) for nm light. Also, a graph of distortion aberration shows distortion for light having a wavelength of 546.10 nm.

Table 3 shows the radius of curvature, thickness or distance, refractive index and Abbe number of the second embodiment of the imaging lens.

side number Radius of curvature (R) thickness or distance (d) Refractive Index (Nd) Abbe number (Vd) S11 -36.1944 1.319 1.5311 56.5 S12 2.965159 6.051559 S21 16.36467 2.8 1.5311 56.5 S22 -6.05369 0.1 AS(stop) 1.00E+18 3.197186 S31 4.472282 1.858068 1.589 61.2 S32 -4.12745 0.05 S41 -4.69987 0.5 1.642 22.4 S42 14.53251 0.973202

In Table 3, curvatures of the target surface and the imaging surface of the first lens 110, the second lens 120, the aperture (AS), and the third lens 130 and the fourth lens 140 are sequentially described, and the curvature When is positive (+), it is bent toward the object side, and when it is negative (-), it is bent toward the light receiving element. When the curvature is infinite, it is flat, the thickness is described corresponding to each target surface, and the distance to an adjacent lens or the like corresponding to the imaging surface is described.

In the second embodiment, the distance d4 between the image formation surface S22 of the second lens 120 and the diaphragm AS is 0.1 mm, and the distance d4 between the diaphragm AS and the target surface S31 of the third lens 130 The distance d5 between them is 3.197186 mm, and d5 may be smaller than d4. That is, the second lens 120 may be disposed closer to the iris AS than the third lens 130 . This structure is designed so that the third lens 130 is less affected by heat, and a low-distortion image can be obtained by the imaging lens according to the embodiment.

And, by minimizing the air gap between the third lens 130 and the fourth lens 140, the third lens 130 and the fourth lens 140 increase low dispersion performance and minimize aberration. It can be seen that the imaging surface S32 of the third lens 130 and the target surface S41 of the fourth lens 140 may be spaced apart from each other by an interval of 0.05 mm so as to maintain a constant distance while maintaining a constant distance.

In the second embodiment, the refractive power of the first lens 110 is -0.196, the refractive power of the second lens 120 is 0.115, the refractive power of the third lens 130 is 0.252, and the refractive power of the fourth lens 140 is 0.252. The refractive power is -0.183.

The focal length of the first lens 110 is -5.101, the focal length of the second lens 120 is 8.697, the focal length of the third lens 130 is 3.961, and the focal length of the fourth lens 140 is -5.476. am.

Also, the total focal length of the imaging lens according to the second embodiment is 3.1693 mm.

Although not shown, the surface of each lens may be coated to prevent reflection or improve surface hardness.

Table 4 shows the conic constant (k) and aspherical surface coefficients (A to D) of each lens surface in the second embodiment.

side number K A B C D S11 -38.998765 0.212466E-03 -.398223E-05 0.197458E-07 -.706309E-11 S12 -0.493508 0.813849E-03 0.227856E-03 -.203029E-04 0.235975E-05 S21 -40.792050 -.126510E-02 -.408383E-03 0.476455E-04 -.445578E-05 S22 -0.225426 -.192012E-02 -.779158E-04 0.115687E-04 -.126901E-05 S31 -0.017055 -.424069E-04 0.193853E-05 -.523047E-05 0.421021E-05 S32 -1.250524 0.216519E-02 0.254725E-03 0.116793E-04 -.410740E-05 S41 -4.062207 -.248634E-02 0.775096E-03 -.382847E-04 -.794010E-05 S42 -0.867839 0.311432E-02 0.403252E-03 -.495979E-04 0.214033E-05

5 is a graph showing an aberration diagram of a second embodiment of an imaging lens, showing longitudinal spherical aberration, astigmatic field curves, and distortion in order from the left.

In FIG. 5 , the Y-axis means the size of an image, the X-axis means the focal length (in mm) and distortion (in %), and as the curves approach the Y-axis, the aberration correction function can be improved. In addition, the graph of longitudinal spherical aberration in FIG. 5 shows the longitudinal spherical aberration for light having wavelengths of 435.80 nm, 486.10 nm, 546.10 nm, 587.60 nm, 656.30 nm, and 850.00 nm, and the graph of astigmatism shows wavelength of 587.60 nm. Shows aberrations on the sagittal surface (S) and tangential surface (T) for nm light. Also, a graph of distortion aberration shows distortion for light having a wavelength of 587.60 nm.

Table 5 shows the radius of curvature, thickness or distance, refractive index and Abbe number of each lens of the third embodiment of the imaging lens.

side number Radius of curvature (R) thickness or distance (d) Refractive Index (Nd) Abbe number (Vd) S11 -36.1944 1.319 1.5311 56.5 S12 2.965159 5.712527 S21 16.36467 2.8 1.5311 56.5 S22 -6.05369 0 AS(stop) 1.00E+18 3.082622 S31 4.860152 2.512555 1.589 61.2 S32 -3.39416 0.1 S41 -3.12216 0.464376 1.642 22.4 S42 -58.4582 0.879034

In Table 5, the curvatures of the target surface and the imaging surface of the first lens 110, the second lens 120, the aperture (AS), and the third lens 130 and the fourth lens 140 are sequentially described, and the curvature When is positive (+), it is bent toward the object side, and when it is negative (-), it is bent toward the light receiving element. When the curvature is infinite, it is flat, the thickness is described corresponding to each target surface, and the distance to an adjacent lens or the like corresponding to the imaging surface is described.

In the third embodiment, the distance d4 between the imaging plane S22 of the second lens 120 and the aperture AS is 0 mm, and the distance between the aperture AS and the target plane S31 of the third lens 130 is 0 mm. The distance d5 is 3.082622 mm. That is, since the third lens 130 is disposed relatively far from the aperture AS, the third lens 130 may be less affected by heat, and thus, a low-distortion image may be obtained.

And, by minimizing the air gap between the third lens 130 and the fourth lens 140, the third lens 130 and the fourth lens 140 increase low dispersion performance and minimize aberration. It can be seen that the imaging surface S32 of the third lens 130 and the target surface S41 of the fourth lens 140 may be spaced apart from each other at an interval of 0.01 mm so as to maintain a constant distance while maintaining a constant distance. In addition, unlike the first and second embodiments, in the third embodiment, the distance between the image plane S32 of the third lens 130 and the target plane S41 of the fourth lens 140 may be closer, which is It may vary according to the radius of curvature or shape of the third lens and the fourth lens.

In the third embodiment, the refractive power of the first lens 110 is -0.196, the refractive power of the second lens 120 is 0.115, the refractive power of the third lens 130 is 0.261, and the refractive power of the fourth lens 140 is The refractive power is -0.194.

The focal length of the first lens 110 is -5.101, the focal length of the second lens 120 is 8.697, the focal length of the third lens 130 is 3.825, and the focal length of the fourth lens 140 is -5.155. am.

Also, the total focal length of the imaging lens according to the third embodiment is 3.1785 mm.

Although not shown, the surface of each lens may be coated to prevent reflection or improve surface hardness.

Table 6 shows the conic constant (k) and aspherical surface coefficients (A to D) of each lens surface in the third embodiment.

side number K A B C D S11 -38.998765 0.212466E-03 -.398223E-05 0.197458E-07 -.706309E-11 S12 -0.493508 0.813849E-03 0.227856E-03 -.203029E-04 0.235975E-05 S21 -40.792050 -.126510E-02 -.408383E-03 0.476455E-04 -.445578E-05 S22 -0.225426 -.192012E-02 -.779158E-04 0.115687E-04 -.126901E-05 S31 0.202506 -.402681E-03 -.152561E-03 0.265831E-04 -.286531E-05 S32 -0.757944 0.182120E-02 0.626393E-03 -.568018E-04 0.180974E-05 S41 -3.096583 -.206318E-02 0.526577E-03 -.272536E-04 0.574780E-06 S42 -10.000000 0.870663E-02 -.814185E-03 0.979174E-04 -.452648E-05

6 is a graph showing an aberration diagram of a third embodiment of an imaging lens, showing longitudinal spherical aberration, astigmatic field curves, and distortion in order from the left.

In FIG. 6 , the Y axis means the size of an image, the X axis means the focal length (in mm) and distortion (in %), and as the curves approach the Y axis, the aberration correction function can be improved. Further, the graph of longitudinal spherical aberration in FIG. 6 shows the longitudinal spherical aberration for light having wavelengths of 435.80 nm, 486.10 nm, 546.10 nm, 587.60 nm, 656.30 nm, and 850.00 nm, and the graph of astigmatism shows wavelength of 587.60 nm. Shows aberrations on the sagittal surface (S) and tangential surface (T) for nm light. Also, a graph of distortion aberration shows distortion for light having a wavelength of 587.60 nm.

7A and 7B are views showing a fourth embodiment of an imaging lens.

Referring to FIGS. 7A and 7B , the imaging lens according to the fourth embodiment includes a plurality of lenses 100 to 140 sequentially disposed inside a lens barrel 400 and a spacing member (disposed between the plurality of lenses). 200) may be included.

Also, the plurality of lenses 100 to 140 may be sequentially disposed in a direction from the object side to the image side, and may include a first lens to an nth lens, where n may be an integer of 2 or greater.

The first lens 110 may have a concave shape such that an object surface of the first lens collects light in order to implement a wide-angle lens, and may have negative refractive power. Here, when the plurality of lenses 100 to 140 are disposed in the lens barrel 400, the target surface of the first lens 110 is exposed to the outside. It minimizes the impact caused by and makes scratches less likely to occur.

In addition, the plurality of lenses may be vertically disposed inside the lens barrel 400 in the drawing, and the target surface of one lens may be disposed to face the imaging surface of the adjacent lens.

Also, the second lens 120 may be disposed so that the imaging surface of the first lens 110 and the target surface of the second lens 120 face each other, and the second lens 120 may have positive refractive power. . Also, the third lens 130 may be made of glass and have positive refractive power, and the fourth lens 140 may be made of plastic and have negative refractive power.

In addition, the gap maintaining member 200 is disposed between the adjacent lenses to maintain a gap between the adjacent lenses.

Here, the spacing maintaining member 200 has outer circumferential surfaces 214 and 224 in contact with the inner circumferential surface 410 of the lens barrel 400, and is disposed between lenses to maintain a distance between adjacent lenses. Further, the gap maintaining member 200 includes first coupling surfaces 211 and 221 in contact with the imaging surface of the (n-1)th lens and second coupling surfaces 212 and 222 in contact with the object surface of the n-th lens. In addition, at least one contact surface coupled to the coupling surface of the gap maintaining member is included in the target surface and / or the imaging surface of the first to fourth lenses 110 to 140, and at least a portion of the contact surface may be flat. .

In addition, on the inner circumferential surface of the gap maintaining member 200, anti-reflecting units 213 and 223 are provided to prevent diffuse reflection of light emitted from the imaging surface of the (n-1)th lens to the target side surface of the n-th lens. can be formed

In the embodiment, the imaging lens is provided as the first to fourth lenses 110 to 140, and the first distance maintaining member 210 may be disposed between the first lens 110 and the second lens 120. . In addition, the first gap maintaining member 210 includes a first coupling surface 211 in contact with the imaging surface of the first lens 110 and a second coupling surface 212 in contact with the target surface of the second lens 120. can do. And, the first coupling surface 211 and the second coupling surface 212 are coupled to the first lens 110 and the second lens 120, respectively, to form a gap between the first lens 110 and the second lens 120. You can keep your distance.

In addition, a first anti-reflective part 213 may be formed on an inner circumferential surface of the first gap maintaining member 210 .

Here, the first anti-diffuse reflection portion 213 may include a concave-convex portion, and an angle formed between two facing surfaces of protrusions of the concave-convex portion may be 50° to 70°.

On the other hand, the first coupling surface 211 and the second coupling surface 212 of the first gap maintaining member 210 are the first contact surface 111 and the second lens 120 of the imaging surface of the first lens 110, respectively. It may make surface contact with the second contact surface 121 of the target surface. Here, the first coupling surface 211 and the second coupling surface 212 are the size of the first lens 110 and the second lens 120, the imaging surface of the first lens 110 and the second lens 120 ), the shape or area may vary depending on the shape of the target surface.

That is, when the imaging surface of the first lens 110 is concave and the target surface of the second lens 120 is flat or concave, as in the embodiment, the first coupling surface 211 and the second coupling surface 212 is formed to have a larger area than the first contact surface 111 and the second contact surface 121, respectively, so that the first distance maintaining member 210 may be disposed between the first lens 110 and the second lens 120.

Here, a plurality of lenses may be disposed in which the aperture of the first lens 110 is larger than that of the second lens 120 and the aperture of the second lens 120 is larger than that of the third lens 130. In particular, when the aperture of the first lens 110 is relatively large compared to other lenses to implement a wide angle, the above-described structure more stably maintains the distance between the first lens 110 and the second lens 120, can support you

Meanwhile, the second distance maintaining member 220 may be disposed between the second lens 120 and the third lens 130 . And, the second gap maintaining member 220 has a first coupling surface 221 in contact with the imaging surface of the second lens 120 and a second coupling surface 222 in contact with the target surface of the third lens 130, respectively. It may be coupled to the second lens 120 and the third lens 130 to maintain a distance between the second lens 120 and the third lens 130 .

In addition, a second anti-reflective part 223 may be formed on an inner circumferential surface of the second gap maintaining member 220 .

Here, the third anti-diffuse reflection portion 223 may include a concave-convex portion, and an angle formed between two facing surfaces of protrusions of the concave-convex portion may be 50° to 70°.

In addition, a step 224 may be formed on the first coupling surface 221 of the second gap maintaining member 220, and the step 224 has a predetermined height from the imaging surface of the second lens 120, It may be formed to secure a space in which the central portion of the second lens 120 is disposed.

In addition, the lower surface of the step 224 may be a diaphragm capable of adjusting the amount of light passing through the second lens 120 and entering the third lens 130 .

Here, a space in which the central portion of the imaging surface of the convex second lens 120 is disposed is secured, and the light transmitted through the second lens 120 through the diaphragm disposed on the second distance maintaining member 220 is removed. Among the distances between adjacent lenses, the distance between the second lens 120 and the third lens 130 may be the largest so as to secure a passage through which the third lens 130 is incident.

In addition, a third spacing member 300 may be disposed between adjacent lenses.

Also, the third gap maintaining member 300 has an outer circumferential surface 315 in contact with the inner circumferential surface 410 of the lens barrel 400, and is disposed between the third lens 130 and the fourth lens 140 so as to provide a space between the lenses. You can keep your distance. In addition, the third gap maintaining member 300 may include a first coupling surface 311 in contact with the imaging surface of the third lens 130 and a second coupling surface 312 in contact with the target surface of the fourth lens. .

Here, the third gap maintaining member 300 has a first coupling surface 311 coupled to the fourth lens 140 is provided as a flat surface, so that the imaging surface of the third lens and the target surface of the fourth lens are at the edge. can be connected by contact. For example, a coupling flange 135 contacting the first coupling surface 311 may be formed at an edge of the image forming surface of the third lens 130 .

That is, the coupling flange 135 is formed on the edge of the third lens 130 in a direction perpendicular to the direction in which the plurality of lenses are stacked, and the upper surface of the coupling flange 135 has the second gap maintaining member 220. A first contact surface 131 coupled to the second coupling surface 222 is formed, and a second contact surface coupled to the first coupling surface 311 of the third spacing member 300 is formed on the lower surface of the coupling flange 135. (132) may be formed. In addition, the third spacing member 300 may be disposed between the coupling flange 135 and the first contact surface 141 formed at the edge of the fourth lens 140 to be horizontal. Here, the third spacing member 300 is disposed in a ring shape with flat upper and lower surfaces, and the second contact surface 132 of the third lens 130 and the fourth lens 140 contact the third spacing member 300. The first contact surfaces 141 of may be disposed parallel to each other.

Conventionally, when a distance maintaining member is disposed between a fourth lens having a convex surface and a concave surface corresponding to one surface of the third lens, a groove is formed at the edge of the fourth lens having a concave surface to shape the groove. A gap maintaining member corresponding to was disposed to maintain a distance from the third lens.

This structure has a problem in that the third lens is damaged because the edge of the gap maintaining member disposed in the groove is in contact with the convex surface of the third lens, and the injection process for making the groove in the fourth lens to dispose the gap maintaining member Since this was necessary, there was a problem in that the manufacturing yield of the imaging lens was lowered.

The imaging lens described above may be applied to a camera module including a filter that selectively transmits light passing through the imaging lens according to a wavelength and a light-receiving element that receives the light passing through the filter.

In addition, the camera module including the above-described imaging lens may be incorporated in various digital devices such as a digital camera, a smart phone, a laptop computer, and a tablet PC. In particular, distortion of a photographed image can be minimized by being built into a digital device capable of capturing an image by implementing a wide angle.

Although the above has been described with reference to the embodiments, this is only an example and does not limit the present invention, and those skilled in the art to which the present invention belongs will not deviate from the essential characteristics of the present embodiment. It will be appreciated that various variations and applications are possible. For example, each component specifically shown in the embodiment can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention as defined in the appended claims.

110: first lens 120: second lens
130: third lens 140: fourth lens
150: filter 160: cover glass
170: light receiving element 200, 300: spacing maintaining member
211, 221, 311: first coupling surface 212, 222, 312: second coupling surface
213, 223: anti-glare part 400: lens barrel
AS: Aperture

Claims (14)

Including first to fourth lenses sequentially arranged in a direction from the object side to the imaging side;
The first lens has negative refractive power, the second lens and the third lens have positive refractive power, and the fourth lens has negative refractive power;
The refractive index of the third lens is greater than 1.57 and less than 1.60,
An imaging lens that satisfies Equation 1.
<Equation 1>
-40.0 < R1+R2 < -25.0, where R1 is the radius of curvature of the object surface of the first lens, and R2 is the radius of curvature of the imaging surface of the first lens. Including first to fourth lenses sequentially arranged in a direction from the object side to the imaging side;
The first lens has negative refractive power, the second lens and the third lens have positive refractive power, and the fourth lens has negative refractive power;
The Abbe number of the third lens is greater than 60 and less than 64;
An imaging lens that satisfies Equation 1.
<Equation 1>
-40.0 < R1+R2 < -25.0, where R1 is the radius of curvature of the object surface of the first lens, and R2 is the radius of curvature of the imaging surface of the first lens. According to claim 1,
An imaging lens in which an Abbe number of the third lens is greater than 60 and less than 64. According to claim 1 or 2,
The conic constant of the target surface of the third lens is greater than -0.10 and less than 0.21;
The imaging lens of the third lens has a Conic constant greater than -1.4 and less than -0.7. According to claim 1 or 2,
and an diaphragm disposed between the second lens and the third lens. According to claim 1 or 2,
At least one of the first lens to the fourth lens is made of glass. Including first to fourth lenses sequentially arranged in a direction from the object side to the imaging side;
The first lens has a concave target surface and has negative refractive power;
The second lens has a positive refractive power,
The third lens is made of glass and has positive refractive power;
The fourth lens is made of plastic and has negative refractive power;
A gap maintaining member disposed between neighboring lenses to maintain a distance between the neighboring lenses;
The gap maintaining member includes a coupling surface including a plane coupled to the target surface and the imaging surface of the neighboring lens, respectively,
The conic constant of the target surface of the third lens is greater than -0.10 and less than 0.21;
The imaging lens of the third lens has a Conic constant greater than -1.4 and less than -0.7. According to claim 7,
The imaging lens of claim 1 , wherein a diffuse reflection prevention portion is formed on an inner circumferential surface of the gap maintaining member. According to claim 7,
The imaging lens of claim 1 , wherein at least one contact surface coupled to a coupling surface of the gap maintaining member is included on an object surface and/or an image formation surface of the first lens to the fourth lens, and at least a portion of the contact surface is flat. According to claim 8,
The imaging lens of claim 1 , wherein the heat radiation preventing portion of the gap maintaining member includes a concave-convex portion. According to claim 7,
Among the distances between adjacent lenses, the distance between the second lens and the third lens is the largest. According to claim 7,
An imaging lens having an aperture of the first lens larger than an aperture of the second lens, and an aperture of the second lens larger than an aperture of the third lens. housing; and
A camera module comprising the imaging lens of any one of claims 1 to 3 and 7 to 12 disposed in the housing. A digital device comprising the camera module of claim 13.

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