TWI894991B - Lens assembly - Google Patents

Abstract

The present invention provides a lens module, which has an optical axis from an object side to a image side and is sequentially provided with a first lens, a second lens, a third lens, an aperture, a fourth lens and a fifth lens. The first lens has positive refractive power, and its lens is a biconvex lens. The second lens has positive refractive power, and its lens is a plano-convex lens. The third lens has negative refractive power, and its lens is a plano-concave lens. The second lens and the third lens are planarly bonded to form a cemented lens. The fourth lens has negative refractive power and its lens is a meniscus lens. The fifth lens has negative refractive power and its lens is a meniscus lens. A short throw projection lenses thus improve image quality and reduce throw ratio

Description

lens module

The present invention relates to a lens module, in particular to a short-throw projection lens module.

A projector is an object that can output images. From early slides to today's digital projectors, digital projectors are used in a wide range of applications, such as game consoles, DVDs, computers, etc., which require the image to be projected outward to a specific location for users to watch. Digital projectors can be divided into two types: single-lens projectors and three-lens projectors. The difference lies in the number of lenses. The three-lens projector uses three lenses to project red, green, and blue. Blue trichromatic light adjusts the intensity of red, green, and blue by matching the color of the pattern with the ratio of the three colors. Single-lens projectors can project patterns using only a single lens. Compared to three-lens projectors, single-lens projectors have the advantages of being lighter and cheaper, but they are more prone to overheating and are suitable for short-term use. Three-lens projectors are suitable for large spaces such as theaters due to cost and projection distance considerations.

Although single-shot projectors are lighter than three-shot projectors, they are not light enough to be carried around easily. Therefore, a pico projector is an option for portability. Compared to single-shot projectors, pico projectors are smaller and lighter, and can be used with other mobile products.

Today's micro projector projection technologies can be roughly divided into four categories: LCD, DLP, LCoS, and laser scanning.

LCD projection technology is similar to LCD screens, but the location of the optical film is different. The optical film of LCD screens is located in the projection system, while the optical film of micro projectors is located in the optical engine. The imaging process is to overlap the image using red, green, and blue light or to split a single light source into red, green, and blue light and then further overlap the red, green, and blue light.

DLP projection technology utilizes a light source, a color wheel, a digital micromirror device (DMD), and a projection lens. If the light source uses red, green, and blue LEDs, a color wheel is not required. The DMD primarily controls the light reflection behavior of each micromirror, corresponding to a specific pattern. This allows for faster image transitions than LCD methods.

LCoS projection technology is similar to LCD projection technology. However, LCD uses a polarizing filter to process a single polarization and another polarizing filter to remove other polarizations. LCoS projection technology uses a polarization dichroic filter to transmit specific polarized light through the polarization dichroic filter, while the remaining polarized light is reflected.

Laser scanning technology primarily uses one or two mirrors to directly reflect laser light. Similar to the digital micromirror devices used in DLP projection technology, these mirrors can be adjusted in angle. However, the mirrors in laser scanning technology can be adjusted in more angles than those in DLP technology. The mirrors in laser scanning technology can be adjusted in two axes: horizontal and vertical. Laser scanning technology that uses laser light as a light source has drawbacks such as its high cost and poor image quality due to the laser spot.

The aforementioned micro-projector projects images using the aforementioned method. A lens that meets the requirements is required to project the image. The lens assembly can be assembled with lenses to create a lens combination. The lens combination references parameters such as focal length, refractive index, lens concave-convex combination, radius of curvature, lens thickness, degree of dispersion, refractive index, and Abbe number. Therefore, these parameters are taken into consideration during manufacturing.

The dispersion number affects image quality: higher dispersion leads to lower clarity, and vice versa. The refractive index and Abbe number also affect the degree of dispersion. The refractive index and dispersion are positively correlated, meaning higher refractive index leads to higher dispersion and lower clarity. The Abbe number and dispersion are negatively correlated, meaning higher Abbe number leads to lower dispersion and higher clarity.

Among the commonly used lens formulas, the lens maker's formula shows that the lens thickness, lens material, lens object side curvature radius and lens image side curvature radius all affect the focal length of the lens.

The object-side and image-side structures of a lens affect the lens refractive index, and the lens refractive index affects the lens focal length.

In general, convex lenses are used for focusing, while concave lenses are used for diverging. If the object side of the lens is convex, the refractive index is positive, while if the object side is concave, it is negative. The opposite is true for the image side: convex lenses have negative refractive index, while concave lenses have positive refractive index. If the object side and image side lenses are different lenses, the two values should be compared.

Short-throw projection lenses require sufficient projection space for adequate image quality, which translates to a high throw ratio. The challenge is how to reduce the throw distance to achieve adequate image quality.

The present invention provides a lens module having an optical axis from the object side to the image side. A first lens with positive refractive power, a second lens with positive refractive power, a third lens with negative refractive power, an aperture, a fourth lens with negative refractive power, and a fifth lens with negative refractive power are sequentially arranged in the module. The first lens is a biconvex lens, the second lens is a plano-convex lens, the third lens is a plano-concave lens, and the fourth and fifth lenses are concave-convex lenses. The second and third lenses are bonded together to form a bonded lens. This short-throw projection lens thus improves image quality and reduces throw ratio.

One object of the present invention is to provide a lens module having an internal lens assembly comprising five lenses and an aperture. The lens assembly of the lens module can improve the imaging quality and throw ratio of a short-throw projection lens.

To achieve the above-mentioned objectives, the present invention provides a lens module having an optical axis from an object side to an image side and sequentially provided with a first lens, a second lens, a third lens, an aperture, a fourth lens, and a fifth lens.

The first lens is a biconvex lens, a first object-side surface of the first lens has a first convex surface near the optical axis, a first image-side surface of the first lens has a second convex surface near the optical axis, the second lens is a plano-convex lens, a second object-side surface of the second lens has a third convex surface near the optical axis, a second image-side surface of the second lens has a first plane near the optical axis, the third lens is a plano-concave lens, a third object-side surface of the third lens has a second plane near the optical axis, and one of the third lens The third image-side surface has a first concave surface near the optical axis. The second lens and the third lens are bonded together via the first plane and the second plane to form a glued lens. The fourth lens is a meniscus lens. A fourth object-side surface of the fourth lens has a second concave surface near the optical axis. A fourth image-side surface of the fourth lens has a fourth convex surface near the optical axis. The fifth lens is a meniscus lens. A fifth object-side surface of the fifth lens has a third concave surface near the optical axis. A fifth image-side surface of the fifth lens has a fifth convex surface near the optical axis.

The first lens has a first refractive power, the second lens has a second refractive power, the third lens has a third refractive power, the fourth lens has a fourth refractive power, and the fifth lens has a fifth refractive power.

The first refractive force is a positive value, the second refractive force is a positive value, the third refractive force is a negative value, the fourth refractive force is a negative value, and the fifth refractive force is a negative value.

The second lens has a second Abbe number of Vd2, the third lens has a third Abbe number of Vd3, and the fourth lens has a fourth Abbe number of Vd4, which satisfies the following condition: 101.74 < Vd2 + Vd3 + Vd4 < 110.

The first lens has a first thickness on the optical axis of CT1, the second lens has a second thickness on the optical axis of CT2, the third lens has a third thickness on the optical axis of CT3, the fourth lens has a fourth thickness on the optical axis of CT4, and the fifth lens has a fifth thickness on the optical axis of CT5, which satisfy the following conditions: CT5/CT4 < 1.35 and 0.59 < (CT1+CT2+CT4+CT5)/CT3 < 10.

The sum of the three air gaps between the first lens to the fifth lens is Gaa, and the sum of the thicknesses of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens on the optical axis is ALT, which meets the following conditions: 9<ALT and Gaa<3.

In this lens module, the maximum refractive index of all lenses is Ndmax, which meets the following conditions: 1.67＜Ndmax＜1.85.

In this lens module, the minimum Abbe ratio among all lenses is Vdmin, which satisfies the following condition: 22.11＜Vdmin＜56.11.

The present invention provides an embodiment, wherein the second thickness CT2, the third thickness CT3, and a first air gap G12 between the first lens and the second lens on the optical axis meet the following condition: 0.55＜(G12+CT3)/CT2＜0.75.

The present invention provides an embodiment, wherein the second thickness CT2 and the third thickness CT3 meet the following condition: 0.4＜CT3/CT2＜0.8.

The present invention provides an embodiment, wherein the second thickness CT2 and the total thickness ALT of the first lens to the fifth lens satisfy the following condition: 3.5＜ALT/CT2＜5.5.

The present invention provides an embodiment in which the fourth thickness CT4 and a fourth air gap G45 between the fourth lens and the fifth lens on the optical axis satisfy the following condition: 10 < CT4 / G45 < 12.

The present invention provides an embodiment, wherein the fifth thickness CT5 and the total air gap Gaa between the first lens and the fifth lens on the optical axis satisfy the following condition: 1.5＜Gaa/CT5＜3.5.

The present invention provides an embodiment, wherein the first thickness CT1, the second thickness CT2, the fourth thickness CT4, the fifth thickness CT5, and the sum of the air gaps Gaa between the first lens and the fifth lens on the optical axis meet the following condition: 2＜(CT1+CT2+CT4+CT5)/Gaa＜4.

To help you gain a deeper understanding of the features and effects of this invention, we would like to provide you with a preferred embodiment and detailed explanations as follows:

It is known that short-throw projection lenses require a sufficient throw distance to project sufficient image quality, which means their throw ratio is relatively large. If the distance is insufficient, the projected image quality is insufficient. A lens module is required to reduce the throw ratio. Users can achieve the same projection size and provide sufficient clarity at a shorter throw distance.

The present invention provides a lens module that uses five lenses and an aperture configuration to improve projection image clarity and reduce the throw ratio. This allows a short-throw projection lens to reduce the projection distance required to project a specific size projection while maintaining clarity.

Hereinafter, the present invention will be described in detail by illustrating various embodiments of the present invention with reference to the drawings. However, the concept of the present invention may be embodied in many different forms and should not be construed as being limited to the exemplary embodiments described herein.

Each lens is defined by the lens maker's formula: 1/f = (n-1)(1/R1-1/R2) + [(n-1)2/n](t/R1 R2), where f is the focal length of the lens, n is the refractive index of the material, R1 is the radius of curvature of the lens' object side, R2 is the radius of curvature of the lens' image side, and t is the thickness of the lens. This formula can be used to determine the focal length of each lens.

Please refer to FIG. 1 , which is a schematic diagram illustrating the configuration of an embodiment of the present invention. A lens assembly 1 has an optical axis I extending from the object side 2 to the image side 3 , and includes a first lens 12 , a second lens 14 , a third lens 16 , an aperture 17 , a fourth lens 18 , and a fifth lens 20 , arranged in sequence.

Continuing with the above, referring also to FIG. 2 , which is a light path diagram of an embodiment of the present invention, one side of the light source 10 is disposed on the opposite side of the first object side 122 of the first lens 12 and faces the first convex surface 1222 . The light source 10 projects light, which passes through the first lens 12, the second lens 14, the third lens 16, the aperture 17, the fourth lens 18, and the fifth lens 20, and is then projected outward through the fifth lens 20.

Continuing from the above, the first lens 12 is a biconvex lens, the first object side 122 of the first lens 12 has a first convex surface 1222 near the optical axis I, the first image side 124 of the first lens 12 has a second convex surface 1242 near the optical axis I, the second lens 14 is a plano-convex lens, the second object side 142 of the second lens 14 has a third convex surface 1422 near the optical axis I, the second image side of the second lens 14 has a first plane near the optical axis I, and the third lens 16 is a plano-convex lens. Concave lens. The third object-side surface of the third lens 16 has a second plane near the optical axis I. The third image-side surface 164 of the third lens 16 has a first concave surface 1642 near the optical axis I. The second lens 14 and the third lens 16 are bonded together via the first plane of the second lens 14 and the second plane of the third lens 16 to form a composite lens. The composite lens must be formed by bonding a convex lens and a concave lens. The Abbe numbers of the convex lens and the concave lens are one high and one low. The composite lens is provided to reduce chromatic aberration of the projected light.

Continuing with the above, the fourth lens 18 is a meniscus lens. The fourth object side 182 of the fourth lens 18 has a second concave surface 1822 near the optical axis I, and the fourth image side 184 of the fourth lens 18 has a fourth convex surface 1842 near the optical axis I. The fifth lens 20 is a meniscus lens. The fifth object side 202 of the fifth lens 20 has a third concave surface 2022 near the optical axis I, and the fifth image side 204 of the fifth lens 20 has a fifth convex surface 2042 near the optical axis I.

Continuing with the above, the first lens 12 has a first refractive power, the second lens 14 has a second refractive power, the third lens 16 has a third refractive power, the fourth lens 18 has a fourth refractive power, and the fifth lens 20 has a fifth refractive power, wherein the first refractive power is positive, the second refractive power is positive, the third refractive power is negative, the fourth refractive power is negative, and the fifth refractive power is negative.

Continuing with the above, the second lens 14 has a second Abbe number of Vd2, the third lens 16 has a third Abbe number of Vd3, and the fourth lens 18 has a fourth Abbe number of Vd4, which satisfies the following condition: 101.74 < Vd2 + Vd3 + Vd4 < 110.

Continuing with the above, the first thickness of the first lens 12 on the optical axis I is CT1, the second thickness of the second lens 14 on the optical axis I is CT2, the third thickness of the third lens 16 on the optical axis I is CT3, the fourth thickness of the fourth lens 18 on the optical axis I is CT4, and the fifth thickness of the fifth lens 20 on the optical axis I is CT5, which satisfies the following conditions: CT5/CT4 < 1.35 and 0.59 < (CT1 + CT2 + CT4 + CT5) / CT3 < 10.

Continuing with the above, in the lens module 1, the gaps between the first lens 12 and the fifth lens 20 include the air gap G12 between the first lens 12 and the second lens 14, the air gap between the third lens 16 and the fourth lens 18, and the air gap G45 between the fourth lens 18 and the fifth lens 20. The sum of these three air gaps is Gaa. The sum of the thicknesses of the first lens 12, the second lens 14, the third lens 16, the fourth lens 18, and the fifth lens 20 on the optical axis I is ALT, which satisfies the following conditions: Gaa < 3 and 9 < ALT.

Continuing from the above, among the first lens 12, the second lens 14, the third lens 16, the fourth lens 18, and the fifth lens 20, the maximum refractive index Ndmax and the minimum Abbe index Vdmin satisfy the following conditions: 1.67＜Ndmax＜1.85 and 22.11＜Vdmin＜56.11.

Continuing with the above, the second thickness CT2, the third thickness CT3, and the first air gap G12 between the first lens 12 and the second lens 14 on the optical axis I satisfy the following condition: 0.55 < (G12 + CT3) / CT2 < 0.75.

Continuing with the above, the second thickness CT2 and the third thickness CT3 meet the following conditions: 0.4 < CT3/CT2 < 0.8.

Continuing from the above, the second thickness CT2 and the total thickness ALT of the first lens 12 to the fifth lens 20 meet the following condition: 3.5＜ALT/CT2＜5.5.

Continuing from the above, the fourth thickness CT4, the fourth air gap G45 between the fourth lens 18 and the fifth lens 20 on the optical axis I, satisfies the following condition: 10＜CT4/G45＜12.

Continuing with the above, the fifth thickness CT5 and the total air gap Gaa between the first lens 12 to the fifth lens 20 on the optical axis I satisfy the following condition: 1.5＜Gaa/CT5＜3.5.

Continuing from the above, the first thickness CT1, the second thickness CT2, the fourth thickness CT4, the fifth thickness CT5, and the total space Gaa between the first lens 12 to the fifth lens 20 on the optical axis I meet the following condition: 2＜(CT1+CT2+CT4+CT5)/Gaa＜4.

In the embodiment described above, the lens module 1 of the present invention, through the structure of the first lens 12, the second lens 14, the third lens 16, the aperture 17, the fourth lens 18, and the fifth lens 20, reduces the throw ratio of the image projected by the short-throw projection lens compared to the conventional structure and has higher clarity.

The following is a practical application description of one embodiment of the present invention:

The lens module 1 has an optical axis I extending from the object side 2 to the image side 3 and includes a first lens 12, a second lens 14, a third lens 16, an aperture 17, a fourth lens 18, and a fifth lens 20, arranged in sequence. The second lens 14 and the third lens 16 are bonded together to form a bonded lens. One side of a light source 10 is disposed opposite the first object side 122 of the first lens 12 and faces the first convex surface 1222. The light source 10 projects light, which passes through the first lens 12, the second lens 14, the third lens 16, the aperture 17, the fourth lens 18, and the fifth lens 20, and is then projected outward through the fifth lens 20.

The first lens 12 is a biconvex lens having a first object side 122 and a first image side 124. The first object side 122 has a first convex surface 1222, and the first image side 124 has a second convex surface 1242. The radius of curvature of the first convex surface 1222 is 8.730 mm, and the radius of curvature of the second convex surface 1242 is 7.647 mm. The first lens 12 has a first refractive power, which is positive.

The second lens 14 is a plano-convex lens having a second object side 142 and a second image side. The second object side 142 has a third convex surface 1422 . The second image side has a first plane. The radius of curvature of the third convex surface 1422 is 4.771 mm. The second lens 14 has a second refractive power, which is positive.

The third lens 16 is a plano-concave lens having a third object side and a third image side 164. The third object side has a second plane, and the third image side 164 has a first concave surface 1642. The radius of curvature of the first concave surface 1642 is 2.983 mm. The third lens 16 has a third refractive power, which is negative.

The fourth lens 18 is a meniscus lens having a fourth object side 182 and a fourth image side 184. The fourth object side 182 has a second concave surface 1822, and the fourth image side 184 has a fourth convex surface 1842. The radius of curvature of the second concave surface 1822 is 5.077 mm, and the radius of curvature of the fourth convex surface 1842 is 4.004 mm. The fourth lens 18 has a fourth refractive power, which is negative.

The fifth lens 20 is a meniscus lens having a fifth object side 202 and a fifth image side 204. The fifth object side 202 has a third concave surface 2022, and the fifth image side 204 has a fifth convex surface 2042. The radius of curvature of the third concave surface 2022 is 112.713 mm, and the radius of curvature of the fifth convex surface 2042 is 70.94 mm. The fifth lens 20 has a fifth refractive power D5, which is a negative value.

Among them, the first thickness CT1 of the first lens 12 on the optical axis I is 3.7 mm, the second thickness CT2 of the second lens 14 on the optical axis I is 2.279 mm, the third thickness CT3 of the third lens 16 on the optical axis I is 1.078 mm, the fourth thickness CT4 of the fourth lens 18 on the optical axis I is 1.221 mm, and the fifth thickness CT5 of the fifth lens 20 on the optical axis I is 1.451 mm.

Among them, the first Abbe number Vd1 of the first lens 12 is 55.7, the second Abbe number Vd2 of the second lens 14 is 52.7, the third Abbe number Vd3 of the third lens 16 is 25.4, the fourth Abbe number Vd4 of the fourth lens 18 is 26.1, and the fifth Abbe number Vd5 of the fifth lens 20 is 55.7.

The first refractive index Nd1 of the first lens 12 is 1.54, the second refractive index Nd2 of the second lens 14 is 1.74, the third refractive index Nd3 of the third lens 16 is 1.81, the fourth refractive index Nd4 of the fourth lens 18 is 1.78, and the fifth refractive index Nd5 of the fifth lens 20 is 1.54.

Among them, the first air gap G12 between the first lens 12 and the second lens 14 on the optical axis I is 0.53 mm, the second air gap G34 between the third lens 16 and the fourth lens 18 on the optical axis I is 2.05 mm, and the third air gap G45 between the fourth lens 18 and the fifth lens 20 on the optical axis I is 0.12 mm. The total Gaa of the four air gaps on the optical axis I of the first lens 12 to the fifth lens 20 is 2.7 mm.

In the embodiment described above, the lens module 1 of the present invention, through the structure of the first lens 12, the second lens 14, the third lens 16, the aperture 17, the fourth lens 18, and the fifth lens 20, reduces the throw ratio of the image projected by the short-throw projection lens compared to the conventional structure and has higher clarity.

Therefore, this invention is truly novel, progressive, and industrially applicable, and undoubtedly meets the patent application requirements under Taiwan's Patent Law. Therefore, we have filed an invention patent application in accordance with the law and pray that the Patent Office will grant the patent as soon as possible. I am deeply grateful for your prayers.

However, the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. All equivalent changes and modifications based on the shape, structure, characteristics and spirit described in the patent application scope of the present invention should be included in the patent application scope of the present invention.

1: Lens module 2: Object side 3: Image side 10: Light source 12: First lens 122: First object side 1222: First convex surface 124: First image side 1242: Second convex surface 14: Second lens 142: Second object side 1422: Third convex surface 16: Third lens 164: Third image side 1642: First concave surface 17: Aperture 18: Fourth lens 182: Fourth object side 1822: Second concave surface 184: Fourth image side 1842: Fourth convex surface 20: Fifth lens 202: Fifth object side 2022: Third concave surface 204: Fifth image side 2042: Fifth convex surface I: Optical axis

Figure 1: A schematic structural diagram of one embodiment of the present invention; and Figure 2: A diagram of the optical path of one embodiment of the present invention.

without

1: Lens module

2: Physical side

3: Image side

12: First lens

122: First physical side

1222: First convex surface

124: First image side

1242: Second convex surface

14: Second lens

142: Second physical side

1422: The third convex surface

16: Third lens

164: Third Image Side

1642: First concave surface

17: Aperture

18: Fourth lens

182: The Fourth Physical Side

1822: Second concave surface

184: Fourth Image Side

1842: The fourth convex surface

20: Fifth Lens

202: The Fifth Side

2022: The Third Concave

204: Fifth Image Side

2042: Fifth Convexity

I: Optical axis

Claims (7)

A lens module having an optical axis from an object side to an image side and sequentially provided with a first lens, a second lens, a third lens, an aperture, a fourth lens, and a fifth lens; The first lens is a biconvex lens, a first object-side surface of the first lens has a first convex surface near the optical axis, a first image-side surface of the first lens has a second convex surface near the optical axis, and the first lens has a first refractive power. The second lens is a plano-convex lens, a second object-side surface of the second lens has a third convex surface near the optical axis, a second image-side surface of the second lens has a first plane near the optical axis, and the second lens has a second refractive power. The third lens is a plano-concave lens, a third object-side surface of the third lens has a second plane near the optical axis, and a third image-side surface of the third lens has a second refractive power. The third lens has a third refractive power. The second lens and the third lens are bonded together via the first and second planes to form a bonded lens. The fourth lens is a meniscus lens. A fourth object side of the fourth lens has a second concave surface near the optical axis. A fourth image side of the fourth lens has a fourth convex surface near the optical axis. The fourth lens has a fourth refractive power. The fifth lens is a meniscus lens. A fifth object side of the fifth lens has a third concave surface near the optical axis. A fifth image side of the fifth lens has a fifth convex surface near the optical axis. The fifth lens has a fifth refractive power. wherein the first refractive power is positive, the second refractive power is positive, the third refractive power is negative, the fourth refractive power is negative, and the fifth refractive power is negative; and wherein the second lens has a second Abbe number of Vd2, the third lens has a third Abbe number of Vd3, the fourth lens has a fourth Abbe number of Vd4, the first lens has a first thickness on the optical axis of CT1, the second lens has a second thickness on the optical axis of CT2, the third lens has a third thickness on the optical axis of CT3, the fourth lens has a fourth thickness on the optical axis of CT4, and the fifth lens has a thickness on the optical axis of CT1. The fifth thickness on the optical axis is CT5. In the lens module, the sum of the three air gaps between the first lens and the fifth lens is Gaa. The sum of the thicknesses of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens on the optical axis is ALT. The maximum refractive index of all lenses is Ndmax. The minimum Abbe index of all lenses in the lens module is Vdmin. The following conditions are met: 101.74＜Vd2+Vd3+Vd4＜110; CT5/CT4<1.35; 0.59＜(CT1+CT2+CT4+CT5)/CT3＜10; 9＜ALT; Gaa<3; 1.67＜Ndmax＜1.85; 22.11＜Vdmin＜56.11. The lens module as described in claim 1, wherein the second thickness CT2, the third thickness CT3, and a first air gap G12 between the first lens and the second lens on the optical axis satisfy the following condition: 0.55 < (G12 + CT3) / CT2 < 0.75. The lens module as described in claim 1, wherein the second thickness CT2 and the third thickness CT3 satisfy the following condition: 0.4＜CT3/CT2＜0.8. The lens module of claim 1, wherein the second thickness CT2 and the total thickness ALT of the first lens through the fifth lens satisfy the following condition: 3.5 < ALT / CT2 < 5.5. The lens module of claim 1, wherein the fourth thickness CT4 and a fourth air gap G45 between the fourth lens and the fifth lens on the optical axis satisfy the following condition: 10 < CT4 / G45 < 12. The lens module of claim 1, wherein the fifth thickness CT5 and the sum of the air gaps between the first lens and the fifth lens on the optical axis, Gaa, satisfy the following condition: 1.5 < Gaa/CT5 < 3.5. The lens module as described in claim 1, wherein the first thickness CT1, the second thickness CT2, the fourth thickness CT4, the fifth thickness CT5, and the sum of the air gaps Gaa between the first lens and the fifth lens on the optical axis satisfy the following condition: 2＜(CT1+CT2+CT4+CT5)/Gaa＜4.