Lens assembly

Abstract

A lens assembly is provided. The lens assembly includes: a lens barrel; a plurality of lenses arranged in the optical axis direction and disposed within the lens barrel; and a first spacer disposed between an Nth lens and an (N + 1) th lens adjacent to each other among the plurality of lenses, where the Nth lens may be formed of a first plastic material, and the first spacer may be formed of the same material as the first plastic material, or may be formed of a second plastic material, the second plastic material has a hygroscopic expansion coefficient higher than a hygroscopic expansion coefficient of the first plastic material, and wherein N is a natural number of 2 or more.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0097279, filed on July 23, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes. Technical Field

[0003] The following description relates to technologies associated with lens assemblies. Background Technology

[0004] Camera modules have been implemented in portable electronic devices such as, but not limited to, smartphones, and such camera modules are typically equipped with lens assemblies that include multiple lenses.

[0005] Typically, at least one of the multiple lenses can be formed of a plastic material, and the multiple lenses can be composed of a combination of lenses with different refractive indices.

[0006] In the example of lenses made of plastic materials with high refractive index, the properties of the material may make them susceptible to the effects of temperature and humidity, and due to the different expansion rates of the materials, they may interfere with the surrounding structures, which may cause problems with the deterioration of optical performance when the environment changes rapidly. Utility Model Content

[0007] This summary is provided to present the selection of concepts in a simplified form, while these concepts are further described in the following detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter.

[0008] In general, the lens assembly includes: a lens barrel; a plurality of lenses arranged in the direction of the optical axis and disposed in the lens barrel; and a first spacer disposed between adjacent Nth and N+1th lenses among the plurality of lenses, wherein the Nth lens is formed of a first plastic material, wherein the first spacer is formed of the same material as the first plastic material, or is formed of a second plastic material having a higher hygroscopic expansion coefficient (CHE) than the first plastic material, and wherein N is a natural number of 2 or greater.

[0009] The first spacer may include a first connecting protrusion projecting toward the Nth lens, and wherein the Nth lens may include a second connecting protrusion projecting toward the first spacer, and the second connecting protrusion is connected to the first connecting protrusion.

[0010] The first connecting protrusion can contact the Nth lens in the direction of the optical axis and in the direction intersecting the optical axis, and the second connecting protrusion can contact the first spacer in the direction of the optical axis and in the direction intersecting the optical axis.

[0011] The outer surface of the Nth lens can contact the lens barrel.

[0012] The first connecting protrusion and the second connecting protrusion can be arranged parallel to each other in a direction perpendicular to the optical axis, and the first connecting protrusion can be arranged closer to the optical axis than the second connecting protrusion in a direction perpendicular to the optical axis.

[0013] The inner surface of the second connecting protrusion can be configured to contact the outer surface of the first connecting protrusion.

[0014] The outer surface of the first connecting protrusion may be inclined relative to the optical axis, and the inner surface of the second connecting protrusion may be formed parallel to the outer surface of the first connecting protrusion.

[0015] The outer surface of the first connecting protrusion may be formed at an angle of 90° to 135° with the upper surface of the first spacer.

[0016] The first number of lenses, including the Nth lens, can be formed from polycarbonate series plastic materials.

[0017] The first spacer can be formed from polycarbonate, nylon, or styrene plastic materials.

[0018] The Nth lens and the N+1th lens can be spaced further apart than the lens positioned on the object side of the Nth lens.

[0019] Other features and aspects will become apparent from the following detailed description, drawings, and claims. Attached Figure Description

[0020] Figure 1 A schematic cross-sectional view of an exemplary conventional lens assembly according to one or more embodiments is shown.

[0021] Figure 2 A cross-sectional view of an exemplary lens assembly according to one or more embodiments is shown.

[0022] Figure 3 A perspective view of an exemplary first spacer according to one or more embodiments is shown.

[0023] Figure 4 It shows Figure 2 An enlarged view of part A.

[0024] Figure 5 It shows in Figure 4The principle of suppressing lens distortion in the structure.

[0025] Figure 6 It shows Figure 2 An enlarged view of part B.

[0026] Throughout the accompanying drawings and detailed embodiments, the same reference numerals denote the same elements unless otherwise described. For clarity, illustration, and convenience, the drawings may not be drawn to scale, and the relative dimensions, scale, and depiction of elements in the drawings may be exaggerated. Detailed Implementation

[0027] The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations and / or the order within operations described herein are merely examples and are not limited to the order set forth herein, but can be changed as will be apparent after understanding the disclosure of this application, except for the order of operations and / or the order within operations that must occur in a certain order. As another example, the order of operations and / or the order within operations can be performed in parallel, except for at least a portion of the order of operations and / or at least a portion of the order within operations that must occur in a certain order (e.g., a specific order). Furthermore, for clarity and brevity, descriptions of features known after understanding the disclosure of this application may be omitted.

[0028] Although terms such as “first,” “second,” and “third,” or A, B, (a), (b), etc., may be used herein to describe various components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Each of these terms is not intended to define, for example, the nature, order, or sequence of the corresponding component, assembly, region, layer, or part, but only to distinguish the corresponding component, assembly, region, layer, or part from other components, assemblies, regions, layers, or parts. Therefore, the first component, first assembly, first region, first layer, or first part mentioned in the examples described herein may also be referred to as a second component, second assembly, second region, second layer, or second part without departing from the teachings of the examples.

[0029] Throughout this specification, when a component, element, or layer is described as being “on,” “connected to,” “attached to,” or “joined to” another component, element, or layer, it may be directly “on” (e.g., in contact with), directly “connected to,” directly “attached to,” or directly “joined to” the other component, element, or layer, or one or more other components, elements, or layers may reasonably be present between them. When a component, element, or layer is described as being “directly” “on,” “directly connected to,” “directly attached to,” or “directly joined to” another component, element, or layer, there are no other components, elements, or layers between them. Similarly, expressions such as “between” and “immediately between” and “adjacent to” and “immediately adjacent to” can also be interpreted as described above.

[0030] The terminology used herein is for describing various examples only and is not intended to limit this disclosure. The terms “a,” “an,” and “the” are intended to include the plural meaning as well, unless the context clearly indicates otherwise. As non-limiting examples, the terms “comprising” or “including,” “containing,” and “having” or “owning” specify the presence of stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof, nor do they exclude the alternative presence of features, quantities, operations, components, elements, and / or combinations thereof. Furthermore, while one embodiment may describe the presence of such terms “comprising” or “including,” “containing,” and “having” or “owning” specifying the presence of said features, quantities, operations, components, elements, and / or combinations thereof, other embodiments may exist in which one or more of said features, quantities, operations, components, elements, and / or combinations thereof are absent.

[0031] As used herein, the term “and / or” includes any one of the associated listed items and any combination of any two or more of the associated listed items. The phrases “at least one of A, B, and C” are intended to have a separate meaning, and these phrases also include examples in which one or more of A, B, and C may be present (e.g., any combination of one or more of A, B, and C), unless the corresponding description and implementation require that such an enumeration (e.g., “at least one of A, B, and C”) be interpreted as having a combined meaning.

[0032] The features described herein may be implemented in various forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided merely to illustrate some of the many possible ways in which the methods, apparatus, and / or systems described herein will be apparent upon understanding the disclosure of this application. In this document, the term “may” (e.g., regarding what an example or implementation may include or implement) is used with respect to an example or implementation, meaning that there exists at least one example or implementation that includes or implements this feature, and that all examples and implementations are not limited thereto. The terms “example” or “implementation” as used herein have the same meaning (e.g., the phrase “in one example” has the same meaning as “in one implementation,” and “in one or more examples” has the same meaning as “in one or more implementations”).

[0033] One or more examples relate to a lens assembly, and more specifically, to a lens assembly that responds to deformation of the lens.

[0034] One or more examples may provide a lens assembly that prevents performance degradation due to external factors.

[0035] Figure 1 A schematic cross-sectional view of a conventional lens assembly 100 is shown. The lens assembly 100 may include a lens barrel 110, a plurality of lenses 120, and at least one spacer 130. The plurality of lenses 120 and the spacer 130 may all be disposed within the lens barrel 110.

[0036] The plurality of lenses 120 may include a first lens L1, a second lens L2, a third lens L3, etc., arranged along the optical axis OA. The plurality of lenses 120 may be arranged to be spaced apart from each other by a predetermined distance along the optical axis OA. In addition, the plurality of lenses 120 may be circular lenses or D-shaped cut lenses, wherein a portion of the outline of the D-shaped cut lens is cut off.

[0037] The plurality of lenses 120 may include an optical portion 121 and a rib 123 (or flange) extending from the optical portion 121 in a direction perpendicular to the optical axis.

[0038] The optical portion 121 is the part that exhibits the optical performance of the lens, and the diameter of the edge of the optical portion 121 can correspond to the effective diameter of the lens. Light reflected from an external object can be incident on the optical portion 121 of the lens and can be refracted while passing through the optical portion 121. The optical portions 121 of adjacent lenses can be spaced apart from each other by a predetermined distance in a direction parallel to the optical axis OA.

[0039] Rib 123 can be a portion that secures a lens to another configuration (e.g., lens barrel 110 or another adjacent lens). Rib 123 is a portion that extends radially around the periphery of optical portion 121 and can be integrally formed with optical portion 121. In the example, rib 123 of a particular lens can contact lens barrel 110 and can also contact rib 123 of an adjacent lens.

[0040] In this example, although not shown in the accompanying drawings, the image sensor may be located at the bottom portion of the lens barrel 110. Light reflected from an external object can reach the image sensor through multiple lenses 120.

[0041] At least one spacer 130 may be disposed between adjacent lenses in the lens assembly 100. In an example, the spacer 130 may include a first spacer SP1 disposed between the first lens L1 and the second lens L2, a second spacer SP2 disposed between the second lens L2 and the third lens L3, etc. The spacer 130 may adjust the gap between adjacent lenses or may block unwanted light.

[0042] Spacers 130 can be disposed between adjacent lenses to contact the ribs 123 of the lenses. Spacers 130 can be manufactured with different thicknesses depending on the preset distance between adjacent lenses.

[0043] The spacer 130 may include a through-hole that allows light to pass through. In the example, light passing through the optical portion 121 of a lens disposed on the object side of the spacer 130 can pass through the through-hole of the spacer 130 and enter the optical portion 121 of a lens disposed on the sensor side of the spacer 130.

[0044] The spacer 130 may be provided with a light-absorbing layer to block unwanted light. In a non-limiting example, the light-absorbing layer may be a black film or black iron oxide.

[0045] Spacer 130 may include a spacer formed of a metallic material. In a non-limiting example, the spacer formed of a metallic material may be formed of a non-ferrous metal (e.g., phosphor bronze).

[0046] Additionally, according to one or more embodiments, the spacer 130 may include a spacer formed of a plastic material. A detailed description thereof will be given below.

[0047] The contents of the lens assembly 100 described above can be largely applied to the lens assembly 200 described below (see Figure 2 (In the following text, reference will be made to...) Figures 2 to 6 A lens assembly 200 according to one or more embodiments is described.

[0048] Figure 2It is a cross-sectional view of a lens assembly 200 according to one or more embodiments, and Figure 3 This is a perspective view of the first spacer 230 according to one or more embodiments.

[0049] Reference Figure 2 The lens assembly 200 according to one or more embodiments may include a lens barrel 210, a plurality of lenses 220 disposed in the lens barrel 210 in the direction of the optical axis OA, and a first spacer 230 disposed between adjacent lenses in the plurality of lenses 220, which may be formed of plastic material.

[0050] Multiple lenses 220 can be configured to include n+2 lenses L1 to L(n+2) (where n is a natural number of 2 or greater). Lens assembly 200 may include four or more lenses, and preferably, six or more lenses.

[0051] Multiple lenses 220 may have an object-side side and an image-side side, and they may be shaped to be concave or convex toward the object-side or image-side, depending on the desired optical performance. Alternatively, the multiple lenses 220 may be configured with flat surfaces. Figure 2 The shapes of the multiple lenses 220 shown are merely examples.

[0052] Multiple lenses 220 may be disposed within the lens barrel 210 so as to contact the lens barrel 210. In the example, the multiple lenses 220 may contact the lens barrel 210 at least in the direction intersecting the optical axis OA.

[0053] The multiple lenses 220 may be partially or entirely formed of plastic material. Additionally, some of the multiple lenses 220 may be made of hydrophilic plastic material with high refractive index characteristics and a high coefficient of hygroscopic expansion. For example, some lenses of the multiple lenses 220 may be made of polycarbonate series plastic materials. However, the material of some lenses is not limited to the above-mentioned materials and may be replaced by other materials with similar properties.

[0054] In embodiments, the plurality of lenses 220 may include one or more lenses made of polycarbonate series plastic material. When they comprise multiple lenses made of polycarbonate series plastic material, they may be arranged continuously or discontinuously along the optical axis OA. For example, in Figure 2 In the lens assembly 200 shown, at least the Nth lens Ln can be a lens made of polycarbonate series plastic material.

[0055] Figure 3The first spacer 230 shown can be disposed between the Nth lens Ln and the (N+1)th lens L(n+1) (where N is a natural number of 2 or greater). In other words, in this example, the first spacer 230 can be disposed between a polycarbonate series plastic material lens and an adjacent lens.

[0056] The first spacer 230 can be made of a plastic material having properties similar to those of the Nth lens Ln (e.g., a high coefficient of hygroscopic expansion). Specifically, the first spacer 230 can be made of a material with a coefficient of hygroscopic expansion (CHE) similar to or greater than that of the Nth lens Ln. For example, the first spacer 230 can be a plastic material such as polycarbonate, nylon, or styrene (ABS). However, the material of the first spacer 230 is not limited to the above-mentioned materials and can be replaced with other materials having similar properties.

[0057] In one or more examples, the Nth lens Ln and the first spacer 230 may be made of a plastic material with a hygroscopic expansion coefficient (CHE) of 0.05 to 0.6. In one or more examples, the hygroscopic expansion coefficient (CHE) may be defined as the amount of deformation (strain % / weight gain %) of the sample in response to the amount of moisture absorbed under temperature and humidity conditions (in the environment in which the measurement is performed).

[0058] [Table 1]:

[0059] Division 1 2 3 temperature 85℃ 60℃ 25℃ relative humidity 85％ 90％ 50％

[0060] In the example, the coefficient of hygroscopic expansion (CHE) of the polycarbonate-based plastic material can be from 0.1 to 0.3, preferably from 0.16 to 0.27. In the example, when the first spacer 230 is made of a material different from that of the Nth lens Ln, the first spacer 230 can be made of a plastic material with a coefficient of hygroscopic expansion (CHE) greater than that of the polycarbonate-based plastic material.

[0061] Furthermore, in the example, the Nth lens Ln and the (N+1)th lens L(n+1) can be configured to have a relatively wider gap than other adjacent lenses. For example, the Nth lens Ln and the (N+1)th lens L(n+1) can be configured to have a gap at least wider than that of the lens disposed on the object side of the Nth lens Ln. The first spacer 230 can be formed to have a thickness corresponding to a predetermined distance between the Nth lens Ln and the (N+1)th lens L(n+1) in order to maintain the gap between them.

[0062] Reference Figure 3 and Figure 4 In the example, the first spacer 230 can be formed in a circular shape and can be inserted and disposed within the lens tube 210.

[0063] The first spacer 230 may include an upper surface 231 and a lower surface 232 that are opposite to each other in the direction of the optical axis OA. Figure 4 The first spacer 230 includes the inner surface 233 facing the optical axis OA and the outer surface 234 facing the radial direction.

[0064] The upper surface 231 and lower surface 232 of the first spacer 230 may each have an annular shape, and the surface extending from the inner edge of the upper surface 231 to the inner edge of the lower surface 232 may constitute the inner surface 233. Additionally, the surface extending from the outer edge of the upper surface 231 to the outer edge of the lower surface 232 may constitute the outer surface 234. For example, the inner surface 233 of the first spacer 230 may be a surface formed at an angle relative to the optical axis OA, and the outer surface 234 may be a surface formed approximately parallel to the optical axis OA. However, this is merely an example, and in this example, the outer surface 234 may be modified to fit the shape of the lens barrel 210.

[0065] The upper surface 231 of the first spacer 230 can contact the image-side rib 223 of the Nth lens Ln, and the lower surface 232 can contact the object-side rib 223 of the (N+1)th lens L(n+1). In addition, the outer surface 234 of the first spacer 230 can contact the lens barrel 210.

[0066] The first spacer 230 may include a through hole 235. The inner surface 233 of the first spacer 230 may define the through hole 235. Depending on the shape of the inner surface 233 of the first spacer 230, the through hole 235 may have a shape in which the diameter expands from the upper surface 231 of the first spacer 230 to the lower surface 232 of the first spacer 230.

[0067] The through-hole 235 can overlap with the optical portion 221 of the Nth lens Ln and the N+1th lens L(n+1) in the direction of the optical axis OA.

[0068] In the example, the first spacer 230 can form a specific connecting protrusion by contacting the rib 223 of the Nth lens Ln. Figure 3 In the first spacer 230, the upper surface 231 may be provided with a first connecting protrusion 236 protruding from the upper surface 231 of the first spacer 230 along its inner edge. The first connecting protrusion 236 may be connected with a second connecting protrusion 226, which protrudes from the rib 223 of the Nth lens Ln toward the first spacer 230.

[0069] Figure 4 It shows Figure 2 An enlarged view of part A, and Figure 5 It shows in Figure 4 The principle of suppressing lens distortion in the structure.

[0070] Reference Figure 4 The first connecting protrusion 236 of the first spacer 230 can be disposed inward, that is, closer to the optical axis OA than the second connecting protrusion 226 of the rib 223. For example, the outer diameter of the first connecting protrusion 236 can be smaller than the inner diameter of the second connecting protrusion 226, and the first connecting protrusion 236 and the second connecting protrusion 226 can be disposed parallel to each other in the radial direction (perpendicular to the optical axis OA) of a circle centered on the optical axis OA.

[0071] The first connecting protrusion 236 and the second connecting protrusion 226 can be configured such that they partially face and contact each other in a direction intersecting the optical axis OA. For example, the outer surface 236a of the first connecting protrusion 236 and the inner surface 226a of the second connecting protrusion 226 can contact each other. That is, the first connecting protrusion 236 and the second connecting protrusion 226 can be configured to have surface contact.

[0072] Additionally, the first connecting protrusion 236 can contact a portion of the Nth lens Ln, facing the Nth lens Ln in the direction of the optical axis OA. Similarly, the second connecting protrusion 226 can contact a portion of the first spacer 230, facing the first spacer 230 in the direction of the optical axis OA. For example, the protruding surface 236b of the first connecting protrusion 236 and the rib 223 of the Nth lens Ln can contact each other. Furthermore, the protruding surface 226b of the second connecting protrusion 226 and the upper surface 231 of the first spacer 230 can also contact each other.

[0073] As described above, when the first spacer 230, formed of a material with a high coefficient of hygroscopic expansion, and the Nth lens Ln are combined as described above, when the lens assembly 200 is exposed to a high temperature and high humidity environment, the deformation of the Nth lens Ln can be offset by the deformation of the first spacer 230.

[0074] In high temperature and high humidity environments, external forces caused by the deformation of the lens barrel 210 can be transmitted to multiple lenses 220. Specifically, in the example of the Nth lens Ln, the shape (e.g., curvature) of the lens and the gap between the lenses may change due to the influence of external forces transmitted from the lens barrel 210 caused by the properties of the materials.

[0075] In the example, the Nth lens Ln can have a meniscus shape convex on the image side, and based on the force applied from the outer diameter to the inner diameter, it can change the gap between adjacent lenses by bending from the concave object side to the convex image side. For example, through the above deformation, the gap between the Nth lens Ln and the N+1th lens L(n+1) may become narrower.

[0076] According to one or more embodiments, an external force can be applied to the Nth lens Ln from the first spacer 230 connected to the Nth lens Ln to counteract the force that deforms the Nth lens Ln.

[0077] In this embodiment, the first spacer 230 can deform under high temperature and high humidity conditions to expand in the length direction. The first connecting protrusion 236 of the first spacer 230 can be disposed inside the second connecting protrusion 226 of the N lens Ln and in contact with the surface of the second connecting protrusion 226 facing the direction intersecting with the optical axis OA, so that the external force generated by the first spacer 230 can be transmitted from the inner diameter to the outer diameter, that is, in the opposite direction to the external force generated by the lens barrel 210.

[0078] The surfaces of the first connecting protrusion 236 and the second connecting protrusion 226 facing each other in a direction perpendicular to the optical axis OA can be surfaces inclined relative to the optical axis OA. In the example, the upper surface 231 of the first spacer 230 and the outer surface 236a of the first connecting protrusion 236 can have an angle θ between 90° and 135°. In the example, when the first spacer 230 expands, a force corresponding to the external force transmitted from the lens barrel 210 to the Nth lens Ln can be applied to the Nth lens Ln. The inner surface 226a of the second connecting protrusion 226 can be parallel to the outer surface 236a of the first connecting protrusion 236.

[0079] Reference Figure 5 In the example, the first spacer 230 can expand and deform in both the thickness and length directions. The thickness direction can be parallel to the optical axis OA. In the example, the first spacer 230 and the Nth lens Ln can contact each other in the direction of the optical axis OA, such that the first spacer 230 can compensate for the gap change between the Nth lens Ln and the (N+1)th lens L(n+1) caused by the drooping of the Nth lens Ln when it expands in the thickness direction.

[0080] The description above may primarily concern examples in which the lens assembly 200 can be exposed to high temperature and high humidity environments, but conversely, the same principle can be applied even when the surrounding environment changes back to room temperature and low humidity.

[0081] In other words, the lens assembly 200 according to one or more embodiments can exhibit similar performance under all conditions because factors that can affect optical performance (such as lens gap) remain almost constant even when the surrounding environment (temperature and humidity) changes, thereby improving performance stability.

[0082] In addition, in the connection structure, according to one or more embodiments, the first connection protrusion 236 and the second connection protrusion 226 can guide the assembly position of the Nth lens Ln, thereby helping to align the optical axis OA of the Nth lens Ln.

[0083] Similarly, the ribs 223 of other lenses may also be configured to guide the assembly position.

[0084] Figure 6 yes Figure 2 An enlarged view of part B.

[0085] Reference Figure 6 The plurality of lenses 220 may include a protrusion 227 that protrudes toward the rib 223 of the lens disposed adjacent to the rib 223.

[0086] In the example, the first lens L1 may include a protrusion 227 projecting toward the adjacent second lens L2. In the example of the second lens L2, since the second lens L2 is adjacent to the first lens L1 on the object side and to the third lens L3 on the image side, the second lens L2 may include protrusions 227 projecting toward both the first lens L1 and the third lens L3.

[0087] The assembly positions of multiple lenses 220 can be guided so that the optical axes OA can be aligned via protrusions 227 provided on surfaces facing each other. Therefore, misalignment can be prevented without applying a separate structure to the lens barrel 210 to align the optical axes OA of the multiple lenses 220.

[0088] According to one or more embodiments, the reliability of the product can be improved because the lens performance can be maintained even in various usage environments.

[0089] While this disclosure includes specific examples, it will be apparent upon understanding the disclosure of this application that various changes in form and detail may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered descriptive only and not for limiting purposes. The description of features or aspects in each example is to be applied to similar features or aspects in other examples. Suitable results may also be obtained if the described techniques are performed in a different order, and / or if components in the described system, architecture, device, or circuit are combined in a different manner and / or replaced or supplemented by other components or their equivalents.

[0090] Therefore, in addition to the disclosure above and in all the accompanying drawings, the scope of this disclosure also includes the claims and their equivalents, that is, all variations within the scope of the claims and their equivalents should be interpreted as being included in this disclosure.

Claims

1. A lens assembly, characterized by, Comprising: a lens barrel; a plurality of lenses arranged in a direction of an optical axis and provided in the lens barrel; and a first spacer provided between adjacent Nth and (N+1)th lenses among the plurality of lenses, wherein the Nth lens is formed of a first plastic material, wherein the first spacer is formed of the same material as the first plastic material or a second plastic material having a higher hygroscopic expansion coefficient than a hygroscopic expansion coefficient of the first plastic material, and wherein N is a natural number of 2 or more. The first spacer includes a first coupling protrusion protruding toward the Nth lens, and 2. The lens assembly of claim 1, wherein, wherein the Nth lens includes a second coupling protrusion protruding toward the first spacer, and the second coupling protrusion is coupled with the first coupling protrusion. 3.The lens assembly of claim 2, wherein: the first coupling protrusion is in contact with the Nth lens in a direction of the optical axis and a direction intersecting the optical axis, and the second coupling protrusion is in contact with the first spacer in the direction of the optical axis and the direction intersecting the optical axis. An outer surface of the Nth lens is in contact with the lens barrel.

4. The lens assembly of claim 3, wherein, 5.The lens assembly of claim 3, wherein: the first coupling protrusion and the second coupling protrusion are disposed in parallel to each other in a direction perpendicular to the optical axis, and the first coupling protrusion is disposed closer to the optical axis than the second coupling protrusion in the direction perpendicular to the optical axis. 6.The lens assembly of claim 5, wherein: an inner surface of the second coupling protrusion is disposed to contact an outer surface of the first coupling protrusion. 7.The lens assembly of claim 6, wherein: the outer surface of the first coupling protrusion is inclined with respect to the optical axis, and the inner surface of the second coupling protrusion is formed parallel to the outer surface of the first coupling protrusion. 8.The lens assembly of claim 7, wherein: the outer surface of the first coupling protrusion is formed to have an angle of 90° to 135° with respect to an upper surface of the first spacer. The Nth lens and the (N+1)th lens are disposed with a wider interval than a lens disposed on an object side of the Nth lens.

9. The lens assembly of claim 1, wherein, ​

Images