KR102632840B1 - Optical system and camera module for comprising the same - Google Patents

Abstract

An optical system according to an embodiment of the present invention includes a first lens arranged in order from the object side to the image side; second lens; third lens; fourth lens; and a fifth lens; wherein the second lens has an object side concave toward the object side and an image side concave toward the image side, and the third lens is a meniscus whose object side and image side are convex toward the image side based on the optical axis. The fourth lens has a meniscus shape in which the object side and the image side are convex toward the image side based on the optical axis.

Description

Optical system and camera module including the same {OPTICAL SYSTEM AND CAMERA MODULE FOR COMPRISING THE SAME}

The present invention relates to a camera module, and more specifically, to an optical system and a camera module including the same.

As the technology of portable terminals and cameras built into them develops, demands for slimmer camera modules, lower power consumption, higher resolution, and lighter weight are increasing.

In order to become slimmer and lighter, a camera module including five lenses has been proposed. This camera module includes, from the object side to the image side, a first lens with positive refractive power, a second lens with negative refractive power, a third lens with positive refractive power, a fourth lens with positive refractive power, and a negative refractive power. It may have a structure in which a fifth lens having a refractive power of is arranged in order.

These camera modules have a problem in that it is difficult to obtain satisfactory optical performance due to design constraints.

Therefore, an optical system that satisfies the resolution and can be implemented in a small size and a camera module including the same are needed.

The technical problem to be achieved by the present invention is to provide an optical system and a camera module including the same.

An optical system according to an embodiment of the present invention includes a first lens, which is arranged in order from the object side to the image side; second lens; a third lens having negative refractive power; fourth lens; and

It includes a fifth lens, and the fifth lens has a convex object side surface toward the image side based on the optical axis.

The fourth lens may have an object side convex toward the image side based on the optical axis, and the first lens may have an object side convex toward the image side based on the optical axis.

The second lens may have a convex side of the object toward the image side based on the optical axis.

The third lens may have a concave object side.

The first lens may have positive refractive power.

The second lens may have negative refractive power.

The fourth lens may have positive refractive power.

The fifth lens may have negative refractive power.

Conditional expression 1 can be satisfied.

(Conditional Expression 1) Ψ5> Ψ2>Ψ3

(Here, Ψ5 is the refractive power of the fifth lens, Ψ2 is the refractive power of the second lens, and Ψ3 is the refractive power of the third lens, and the refractive power of each lens can be expressed as the reciprocal of the effective focal length)

Conditional expression 2 can be satisfied.

(Conditional Expression 2) N3d>1.6

(Here, N3d is the refractive index at the d-line of the third lens)

Conditional expression 3 can be satisfied.

(Conditional Expression 3) 20<V3d<30

(Here, V3d is the Abbe number at the d-line of the third lens)

Conditional expression 4 can be satisfied.

(Conditional Expression 4) 0.8<f1/F<1.2

(Here, f1 is the effective focal length of the first lens, and F is the total effective focal length of the optical system.)

Conditional expression 5 can be satisfied.

(Conditional Expression 5) Ψ4> Ψ1

(Here, Ψ4 is the refractive power of the fourth lens, and Ψ1 is the refractive power of the first lens. The refractive power of each lens can be expressed as the reciprocal of the effective focal length.)

According to an embodiment of the present invention, it is possible to obtain an optical system and camera module that has good chromatic aberration correction, satisfies resolution, can cope with high pixel resolution, and can be implemented in a compact size. These camera modules can also be applied to portable terminals that are becoming smaller, slimmer, and more high-performance.

1 is a cross-sectional view of an optical system according to a first embodiment of the present invention.
Figure 2 is a cross-sectional view of an optical system according to a second embodiment of the present invention.
Figure 3 is a cross-sectional view of an optical system according to a third embodiment of the present invention.
Figures 4, 6, and 8 are graphs measuring the spherical aberration, astigmatic field curves, and distortion of the optical system according to the first to third embodiments of the present invention, and Figure 5 , 7 and 9 are graphs measuring the coma aberration of the optical system according to the first to third embodiments of the present invention.
Figure 10 shows a cross-sectional view of a camera module including an optical system according to an embodiment of the present invention.

Since the present invention can be subject to various changes and can have various embodiments, specific embodiments will be illustrated and described in the drawings. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Terms containing ordinal numbers, such as second, first, etc., may be used to describe various components, but the components are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, the second component may be referred to as the first component without departing from the scope of the present invention, and similarly, the first component may also be referred to as the second component. The term and/or includes any of a plurality of related stated items or a combination of a plurality of related stated items.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

Hereinafter, embodiments will be described in detail with reference to the attached drawings, but identical or corresponding components will be assigned the same reference numbers regardless of reference numerals, and duplicate descriptions thereof will be omitted.

The optical system according to an embodiment of the present invention includes a first lens (L1), a second lens (L2), a third lens (L3), and a fourth lens (L4) arranged sequentially from the object side to the image side. ) and a fifth lens (L5). And, the first lens L1 may have positive refractive power. The second lens L2 may have negative refractive power. The third lens L3 may have negative refractive power. The fourth lens L4 may have positive refractive power. The fifth lens L5 may have negative refractive power. And, the optical system according to an embodiment of the present invention can satisfy conditional equations 1 to 3.

(Conditional expression 1) Ø5> Ø2>Ø3

(Conditional Expression 2) N3d>1.6

(Conditional Expression 3) 20<V3d<30

Here, Ø5 is the refractive power of the fifth lens, Ø2 is the refractive power of the second lens, Ø3 is the refractive power of the third lens, N3d is the refractive index at the d-line of the third lens, and V3d is the refractive power of the third lens. This is the Abbe number at the d-line of the lens. The refractive power of each lens can be expressed as the reciprocal of the effective focal length.

If three of the five lenses, such as the second lens (L2), third lens (L3), and fifth lens (L3), have negative refractive power, the surface with a diverging effect increases, and the screen periphery Good imaging performance can be obtained up to.

And, among the three lenses with negative refractive power, the fifth lens (L5) has the greatest refractive power, followed by the refractive power of the second lens (L2) and the third lens (L3). Accordingly, chromatic aberration can be corrected and distortion can also be well corrected.

In addition, if the refractive index (N3d) and Abbe number (V3d) at the d-line of the third lens are set as in conditional equations 2 and 3, the dispersion and refractive power of the third lens are properly maintained, and chromatic aberration and distortion can be corrected. You can.

And, the optical system according to an embodiment of the present invention can further satisfy Conditional Expressions 4 to 5.

(Conditional Expression 4) 0.8<f1/F<1.2

(Conditional Expression 5) Ø4> Ø1

Here, f1 is the effective focal length of the first lens, F is the total effective focal length of the optical system, Ø4 is the refractive power of the fourth lens, and Ø1 is the refractive power of the first lens. The refractive power of each lens can be expressed as the reciprocal of the effective focal length.

In this way, if the ratio of the effective focal length of the first lens L1 to the total effective focal distance satisfies Conditional Equation 4, the optical system can be miniaturized and chromatic aberration can also be maintained well. If f1/F is 0.8 or less, chromatic aberration correction becomes difficult due to the optical power of the first lens L1. And, if f1/F is 1.2 or more, the overall length of the optical system becomes longer, making miniaturization difficult.

Also, among the two lenses having positive refractive power, the refractive power of the fourth lens (L4) may be set to be greater than that of the first lens (L1). Accordingly, chromatic aberration can be corrected and distortion can also be well corrected.

In addition, the refractive power of three lenses (the second lens, the third lens, and the fifth lens) with negative refractive power is designed as in Condition Equation 1, and the refractive power of the two lenses (the first lens, the fourth lens) with positive refractive power is designed as follows. If the refractive power of the lens) is designed as in Conditional Equation 5, the ratio of the focal lengths of the first to fifth lenses is appropriately set to disperse the refractive power, and the sensitivity to eccentricity error due to the shortening of the length of the entire optical system can be reduced, and chromatic aberration The correction effect can be improved.

1 is a cross-sectional view of an optical system according to a first embodiment of the present invention.

Referring to FIG. 1, the optical system 100 includes a first lens 110, a second lens 120, a third lens 130, and a fourth lens arranged sequentially from the object side to the image side. 140, a fifth lens 150, a filter 160, and an image sensor 170.

Light corresponding to image information of an object passes through the first to fifth lenses 110 to 150 and the filter 160 and is incident on the image sensor 170.

The filter 160 may be an IR (Infrared) filter. The filter 160 may block near-infrared rays, for example, light with a wavelength of 700 nm to 1100 nm, from light incident on the camera module. Additionally, the image sensor 170 may be connected to the printed circuit board by a wire. The image sensor 170 may be, for example, a Charge-Coupled Device (CCD) or Complementary Metal-Oxide Semiconductor (CMOS) sensor.

The first lens 110 may have positive refractive power. Additionally, the first lens 110 may include at least one convex surface. For example, the first lens 110 may include a convex surface toward the object. Both sides may be convex.

The second lens 120 may have negative refractive power. Additionally, the second lens 120 may include at least one concave surface. For example, the second lens 120 may include a concave surface on the image side. Both sides may be concave.

The third lens 130 may have negative refractive power. Additionally, the third lens 130 may include a meniscus shape that is convex toward the image side. The upper side may have a shape that is convex toward the upper side.

The fourth lens 140 may have positive refractive power. Additionally, the fourth lens 140 may include a meniscus shape that is convex toward the image side. The upper side may have a shape that is convex toward the upper side.

The fifth lens 150 may have negative refractive power. Additionally, the fifth lens 150 may include a meniscus shape that is convex toward the object. The water side may have a convex shape toward the water side.

At this time, the image side surface of the fifth lens 150 may be aspherical. Accordingly, chromatic aberration in the periphery of the screen can be well corrected.

Additionally, the fifth lens 150 may have at least one inflection point at a position other than the intersection with the optical axis. Here, the inflection point means a point on the aspherical surface where the tangent plane of the vertex of the aspherical surface is perpendicular to the optical axis in the curve of the lens cross-sectional shape within the effective radius. Accordingly, the maximum exit angle of the main light ray incident on the image sensor 170 can be adjusted, preventing the peripheral part of the screen from darkening, and making it easier to secure the telecentric characteristics of the upper light flux.

At least one of the first to fifth lenses 110 to 150 may be made of plastic. Accordingly, an optical system that is lightweight and has low manufacturing costs can be implemented.

Meanwhile, an aperture 180 may be further disposed between the object side and the first lens 110. The aperture 180 can selectively converge incident light and adjust the focal length. If the aperture 180 is located closer to the object than the first lens 110, the overall length can be reduced, making it possible to implement a compact optical system.

Table 1 shows the optical properties of the five lenses according to the example of FIG. 1. In the embodiment of Figure 1, the total effective focal length F is 3.75 mm, and the distance from the object side surface of the first lens to the image surface is 4.55 mm.

Lens No. Lens surface No. Radius of curvature (R, mm) Thickness (mm) Effective focal length (f, mm) Refractive index (Nd) Abesu (Vd) first lens R1 1.530 0.800 3.13 1.531 55.7 R2 14.376 0.100 second lens R3 15.883 0.251 -9.56 1.635 24.0 R4 4.373 0.451 third lens R5 -2.916 0.288 -10.08 1.635 24.0 R6 -5.554 0.100 4th lens R7 -77.330 0.654 2.51 1.544 56.1 R8 -1.370 0.161 5th lens R9 3.383 0.469 -2.49 1.544 56.1 R10 0.923 -

Here, the thickness (mm) represents the distance from each lens surface to the next lens surface. Referring to Table 1, in the optical system according to the first embodiment of the present invention, the first lens has positive refractive power, and the first lens has a positive refractive power. It can be seen that the second lens has a negative refractive power, the third lens has a negative refractive power, the fourth lens has a positive refractive power, and the fifth lens has a negative refractive power. In addition, it can be seen that the refractive power of the fifth lens, Ø5, is 1/2.49, the refractive power of the second lens, Ø2, is 1/9.56, and the refractive power of the third lens, Ø3, is 1/10.08. In addition, it can be seen that the refractive index N3d at the d-line of the third lens is 1.635, and the Abbe number V3d at the d-line of the third lens is 24.0. Additionally, the total effective focal length F of the first embodiment is 3.75, so , f1/F can be seen to be 3.13/3.75. Also, it can be seen that the refractive power of the fourth lens, Ø4, is 1/2.51, and the refractive power of the first lens, Ø1, is 1/3.13.

Figure 2 is a cross-sectional view of an optical system according to a second embodiment of the present invention. Duplicate description of content similar to the first embodiment of FIG. 1 will be omitted.

Referring to FIG. 2, the optical system 200 includes a first lens 210, a second lens 220, a third lens 230, and a fourth lens arranged sequentially from the object side to the image side. 240, a fifth lens 250, a filter 260, and an image sensor 270.

The first lens 210 may have positive refractive power. Additionally, the first lens 210 may include at least one convex surface. For example, the first lens 210 may include a convex surface toward the object. Both sides may be convex.

The second lens 220 may have negative refractive power. Additionally, the second lens 220 may include at least one concave surface. For example, the second lens 220 may include a concave surface on the image side. Both sides can be concave

The third lens 230 may have negative refractive power. Additionally, the third lens 230 may include a meniscus shape that is convex toward the image side. The upper side may have a shape that is convex upward.

The fourth lens 240 may have positive refractive power. Additionally, the fourth lens 240 may include a meniscus shape that is convex toward the image side. The upper side may have a shape that is convex upward.

The fifth lens 250 may have negative refractive power. Additionally, the fifth lens 250 may include a meniscus shape convex toward the object. The water side may have a convex shape toward the water side.

At this time, the image side surface of the fifth lens 250 may be aspherical. Accordingly, chromatic aberration in the periphery of the screen can be well corrected.

Additionally, the fifth lens 250 may have at least one inflection point at a position other than the intersection with the optical axis. Here, the inflection point means a point on the aspherical surface where the tangent plane of the vertex of the aspherical surface is perpendicular to the optical axis in the curve of the lens cross-sectional shape within the effective radius. Accordingly, the maximum exit angle of the main light ray incident on the image sensor 270 can be adjusted, preventing the peripheral part of the screen from darkening, and making it easy to secure the telecentric characteristics of the upper light flux.

Meanwhile, an aperture 280 may be further disposed between the object side and the first lens 210. The aperture 280 can selectively converge incident light and adjust the focal distance. If the aperture 280 is located closer to the object than the first lens 210, the total length can be reduced, and a compact optical system can be implemented.

Table 2 shows the optical characteristics of the five lenses according to the example of FIG. 2. In the embodiment of Figure 2, the total effective focal length F is 3.79 mm, and the distance (TTL) from the object side surface of the first lens to the image surface is 4.58 mm.

Lens No. Lens surface No. Radius of curvature (R, mm) Thickness (mm) Effective focal length (f, mm) Refractive index (Nd) Abesu (Vd) first lens R1 1.548 0.750 3.17 1.531 55.7 R2 14.610 0.100 second lens R3 16.004 0.272 -9.67 1.635 24.0 R4 4.442 0.457 third lens R5 -2.948 0.292 -9.89 1.635 24.0 R6 -5.719 0.100 4th lens R7 354.409 0.658 2.52 1.544 56.1 R8 -1.383 0.168 5th lens R9 3.285 0.462 -2.45 1.544 56.1 R10 0.906 -

Here, the thickness (mm) represents the distance from each lens surface to the next lens surface. Referring to Table 2, in the optical system according to the second embodiment of the present invention, the first lens has positive refractive power, and the first lens has a positive refractive power. It can be seen that the second lens has a negative refractive power, the third lens has a negative refractive power, the fourth lens has a positive refractive power, and the fifth lens has a negative refractive power. Also, it can be seen that the refractive power of the fifth lens, Ø5, is 1/2.45, the refractive power of the second lens, Ø2, is 1/9.67, and the refractive power of the third lens, Ø3, is 1/9.89. In addition, it can be seen that the refractive index N3d at the d-line of the third lens is 1.635, and the Abbe number V3d at the d-line of the third lens is 24.0. Additionally, the total effective focal length F of the first embodiment is 3.79, so , f1/F can be seen to be 3.17/3.79. Also, it can be seen that the refractive power of the fourth lens, Ø4, is 1/2.52, and the refractive power of the first lens, Ø1, is 1/3.17.

Figure 3 is a cross-sectional view of an optical system according to a third embodiment of the present invention. Duplicate description of content similar to the first embodiment of FIG. 1 will be omitted.

Referring to FIG. 3, the optical system 300 includes a first lens 310, a second lens 320, a third lens 330, and a fourth lens arranged sequentially from the object side to the image side. 340, a fifth lens 350, a filter 360, and an image sensor 370.

The first lens 310 may have positive refractive power. Additionally, the first lens 310 may include at least one convex surface. For example, the first lens 310 may include a convex surface toward the object. Both sides can be convex

The second lens 320 may have negative refractive power. Additionally, the second lens 320 may include at least one concave surface. For example, the second lens 320 may include a concave surface on the image side. Both sides can be concave

The third lens 330 may have negative refractive power. Additionally, the third lens 330 may include a meniscus shape that is convex toward the image side. The upper side may have a shape that is convex upward.

The fourth lens 340 may have positive refractive power. Additionally, the fourth lens 340 may include a meniscus shape that is convex toward the image side. The upper side may have a shape that is convex upward.

The fifth lens 350 may have negative refractive power. Additionally, the fifth lens 350 may include a meniscus shape that is convex toward the object. The water side may have a convex shape toward the water side.

At this time, the image side surface of the fifth lens 350 may be aspherical. Accordingly, chromatic aberration in the periphery of the screen can be well corrected.

Additionally, the fifth lens 350 may include at least one inflection point at a position other than the intersection with the optical axis. Here, the inflection point means a point on the aspherical surface where the tangent plane of the vertex of the aspherical surface is perpendicular to the optical axis in the curve of the lens cross-sectional shape within the effective radius. Accordingly, the maximum exit angle of the main light ray incident on the image sensor 370 can be adjusted, preventing the peripheral part of the screen from darkening, and making it easier to secure the telecentric characteristics of the upper light flux.

Meanwhile, an aperture 380 may be further disposed between the object side and the first lens 310. The aperture 380 can selectively converge incident light and adjust the focal length. If the aperture 380 is located closer to the object than the first lens 310, the total length can be reduced, and a compact optical system can be implemented.

Table 3 shows the optical characteristics of the five lenses according to the example of FIG. 3. In the embodiment of Figure 3, the total effective focal length F is 3.77 mm, and the distance (TTL) from the object side surface of the first lens to the image surface is 4.56 mm.

Lens No. Lens surface No. Radius of curvature (R, mm) Thickness (mm) Effective focal length (f, mm) Refractive index (Nd) Abesu (Vd) first lens R1 1.523 0.750 3.18 1.531 55.7 R2 12.271 0.100 second lens R3 12.388 0.265 -10.14 1.635 24.0 R4 4.231 0.456 third lens R5 -2.910 0.287 -10.15 1.635 24.0 R6 -5.466 0.100 4th lens R7 -119.253 0.670 2.55 1.544 56.1 R8 -1.382 0.168 5th lens R9 4.164 0.456 -2.53 1.544 56.1 R10 1.000 -

Here, the thickness (mm) represents the distance from each lens surface to the next lens surface. Referring to Table 3, in the optical system according to the third embodiment of the present invention, the first lens has positive refractive power, and the first lens has a positive refractive power. It can be seen that the second lens has a negative refractive power, the third lens has a negative refractive power, the fourth lens has a positive refractive power, and the fifth lens has a negative refractive power. In addition, it can be seen that the refractive power of the fifth lens, Ø5, is 1/2.53, the refractive power of the second lens, Ø2, is 1/10.14, and the refractive power of the third lens, Ø3, is 1/10.15. In addition, it can be seen that the refractive index N3d at the d-line of the third lens is 1.635, and the Abbe number V3d at the d-line of the third lens is 24.0. Additionally, the total effective focal length F of the first embodiment is 3.77, so , f1/F can be seen to be 3.18/3.77. Also, it can be seen that the refractive power of the fourth lens, Ø4, is 1/2.55, and the refractive power of the first lens, Ø1, is 1/3.18.

In this way, it can be seen that the optical systems according to the first to third embodiments satisfy conditional expressions 1 to 3. And, it can be seen that conditional expressions 4 to 5 are further satisfied.

(Conditional expression 1) Ø5> Ø2>Ø3

(Conditional Expression 2) N3d>1.6

(Conditional Expression 3) 20<V3d<30

Here, Ø5 is the refractive power of the fifth lens, Ø2 is the refractive power of the second lens, Ø3 is the refractive power of the third lens, N3d is the refractive index at the d-line of the third lens, and V3d is the refractive power of the third lens. This is the Abbe number at the d-line of the lens.

(Conditional Expression 4) 0.8<f1/F<1.2

(Conditional expression 5) Ø4>Ø1

Here, f1 is the effective focal length of the first lens, F is the total effective focal length of the optical system, Ø4 is the refractive power of the fourth lens, and Ø1 is the refractive power of the first lens.

The refractive power of each lens can be expressed as the reciprocal of the effective focal length.

Figure 4 is a graph measuring the spherical aberration, astigmatic field curves, and distortion of the optical system according to the first embodiment of the present invention, and Figure 5 is the first embodiment of the present invention. This is a graph measuring the coma aberration of an optical system according to an example.

Figure 6 is a graph measuring the spherical aberration, astigmatic field curves, and distortion of the optical system according to the second embodiment of the present invention, and Figure 7 is a graph measuring the second embodiment of the present invention. This is a graph measuring the coma aberration of an optical system according to an example.

Figure 8 is a graph measuring the spherical aberration, astigmatic field curves, and distortion of the optical system according to the third embodiment of the present invention, and Figure 9 is a graph of the third embodiment of the present invention. This is a graph measuring the coma aberration of an optical system according to an example.

Spherical aberration represents the spherical aberration according to each wavelength, astigmatism represents the aberration characteristics of the tangential plane and sagittal plane according to the height of the image plane, and distortion aberration represents the degree of distortion according to the height of the image plane. indicates. And, coma aberration represents tangential aberration characteristics and digital aberration characteristics at each wavelength depending on the height of the image surface.

*103

*Referring to FIGS. 4 to 9, it can be seen that the optical system according to the embodiment of the present invention has excellent aberration characteristics because the image values appear adjacent to the axis in almost all fields.

Meanwhile, the optical system according to an embodiment of the present invention can be applied to a camera module. Figure 10 shows a cross-sectional view of a camera module including an optical system according to an embodiment of the present invention.

Referring to FIG. 10 , the camera module 600 includes a lens assembly 610, a filter 620, an image sensor 630, a printed circuit board 640, and a lens holder 650.

An image sensor 630 may be mounted on a printed circuit board 640, a filter 620 may be formed on the image sensor 630, and a lens assembly 610 may be formed on the filter 620.

The image sensor 630 may be connected to the printed circuit board 640 by a wire. The image sensor 630 may be, for example, a Charge-Coupled Device (CCD) or Complementary Metal-Oxide Semiconductor (CMOS) sensor.

The filter 620 may be an IR (Infrared) filter. The filter 620 may block near-infrared rays, for example, light with a wavelength of 700 nm to 1100 nm, from light incident on the camera module 600.

The filter 620 and lens assembly 610 may be built into and supported within the lens holder 650.

The camera module according to an embodiment of the present invention may be built into a portable terminal such as a smartphone, tablet PC, laptop computer, or PDA.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art may make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that you can do it.

100: Optical system
110~150: Lens
160: filter
170: image sensor
180: Aperture

Claims (9)

Arranged in order from the object side to the image side,
A first lens having positive refractive power;
a second lens having negative refractive power;
a third lens having negative refractive power;
a fourth lens having positive refractive power; and
It includes a fifth lens having negative refractive power,
The fifth lens has an object side convex with respect to the optical axis,
The second lens is concave on both sides,
The fourth lens has a convex object side on the image side based on the optical axis,
The first lens has an object side convex with respect to the optical axis,
The fourth lens has a positive radius of curvature on the object side and a negative radius of curvature on the image side,
An optical system in which the water side of the fourth lens among the first to fifth lenses has the largest absolute value of curvature radius. delete delete According to paragraph 1,
The third lens has a concave object side,
An optical system in which the image side of the fifth lens among the first to fifth lenses has the smallest absolute value of the radius of curvature. According to paragraph 1,
Among the distances between each lens in the first to fifth lenses, the gap between the third lens and the fourth lens is the smallest,
An optical system that satisfies condition 1.
(Conditional Expression 1) Ψ5>Ψ2>Ψ3
(Here, Ψ5 is the refractive power of the fifth lens, Ψ2 is the refractive power of the second lens, and Ψ3 is the refractive power of the third lens, and the refractive power of each lens can be expressed as the reciprocal of the effective focal length (mm) there is) According to clause 5,
Among the first to fifth lenses, the first lens has the smallest refractive index,
An optical system that satisfies condition 2.
(Conditional Expression 2) N3d>1.6
(Here, N3d is the refractive index at the d-line of the third lens) According to clause 6,
Among the first to fifth lenses, the fourth lens has the largest Abbe number,
An optical system that satisfies condition 3.
(Conditional Expression 3) 20<V3d<30
(Here, V3d is the Abbe number at the d-line of the third lens) In clause 7,
An optical system that satisfies condition 4.
(Conditional Expression 4) 0.8<f1/F<1.2
(Here, f1 is the effective focal length of the first lens, and F is the total effective focal length of the optical system.) According to clause 8,
An optical system that satisfies condition Equation 5.
(Conditional Expression 5) Ψ4> Ψ1
(Here, Ψ4 is the refractive power of the fourth lens, and Ψ1 is the refractive power of the first lens. The refractive power of each lens can be expressed as the reciprocal of the effective focal length (mm))