JP2021119419A - Lens unit and camera module - Google Patents

Abstract

To provide a lens unit and a camera module capable of preventing a decrease in visibility following misting of a lens surface and accumulation of adhered waterdrops and maintaining high transmittance.SOLUTION: A lens unit 11 has a lens group in which plural lenses are arranged along a light axis of the lenses, and a lens barrel 12 for storing the lens group, and a first lens in a side closest to an object in the lens group is provided in an edge of an object side of the lens barrel 12, and includes a lens front surface 13a facing an object side and a lens rear surface 13b facing an image surface side. A reflection prevention film 30 is formed on the lens front surface 13a and the lens rear surface 13b. A hydrophilic film 31 is formed on the reflection prevention film 30 in the lens rear surface 13b.SELECTED DRAWING: Figure 1

Description

The present invention particularly relates to a lens unit and a camera module provided in an in-vehicle camera mounted on a vehicle such as an automobile.

In recent years, in-vehicle cameras have been installed in automobiles to support parking and to prevent collisions by image recognition, and further applications to automatic driving have been attempted.
A camera module such as an in-vehicle camera generally includes a lens group consisting of a plurality of lenses in which a plurality of lenses are arranged along an optical axis, a lens barrel in which the lens group is housed, and a lens group. It includes a lens unit having an aperture member arranged between at least one lens.

As an example of the conventional lens unit, the one described in Patent Document 1 is known. In this lens unit, four lenses are held in a state in which they are arranged in a row with their optical axis directions aligned with each other in the lens barrel.
When such a lens unit is used in an in-vehicle camera, water droplets may adhere to the lens surface exposed from the lens barrel in rainy weather. Such water droplets adhering to the lens surface deteriorate visibility and cause image deterioration. Therefore, in order to prevent water droplets from adhering, for example, the lens surface exposed from the lens barrel (the lens on the object side located closest to the object side). By providing a water-repellent film on the surface (outer surface) of the lens surface, water droplets adhering to the lens surface flow toward the outer peripheral side on the water-repellent film of the lens surface, and the water droplets adhering to the lens surface stay at that location. I try not to.

Further, in this case, an antireflection film (AR coating) is generally provided in advance under the water repellent film of the lens, and the water repellent film is provided on the antireflection film by vapor deposition. Further, the antireflection film is formed not only on the front surface of the lens but also on the back surface of the lens by thin film deposition or the like.

Japanese Unexamined Patent Publication No. 2013-231993

By the way, especially in a lens unit for an in-vehicle camera, high visibility is required, and it is necessary to maintain a high transmittance of the lens. However, as described above, even if a water-repellent film is provided so that water droplets adhering to the lens surface do not stay in the place, if the water-repellent action is insufficient, the retention of water droplets cannot be reliably prevented and visual recognition is possible. Deterioration of sex is inevitable. In addition, the back surface of the lens on which the antireflection film is formed may become cloudy due to a sudden change in temperature or the like, resulting in deterioration of visibility.

The present invention has been made in view of the above circumstances, and provides a lens unit and a camera module that can prevent deterioration of visibility due to fogging on the lens surface and retention of adhering water droplets and can maintain high transmittance. With the goal.

In order to solve the above problems, the present invention is a lens unit including a lens group in which a plurality of lenses are arranged along the optical axis of the lens and a lens barrel in which the lens group is housed. The first lens on the object side of the lens group is provided at the end of the lens barrel on the object side, and has a lens surface facing the object side and a lens back surface facing the image surface side on the lens surface. And an antireflection film is formed on the back surface of the lens.
A hydrophilic film is formed on the antireflection film on the back surface of the lens.

In the present invention, since the hydrophilic film is formed on the back surface of the lens (on the antireflection film), fine water droplets adhering to the back surface of the lens may spread on the hydrophilic film to form a thin water film and stay on the back surface of the lens. do not have. This can contribute to the anti-fog on the back surface of the lens, and therefore, the deterioration of visibility can be prevented.

Further, in the present invention, since the thickness of the hydrophilic film is set as thin as 50 nm or less, it is possible not only to prevent fogging but also to suppress a decrease in the transmittance of the lens due to the formation of the hydrophilic film (high transmittance). Can be maintained). This is particularly useful when used in an in-vehicle camera where high visibility is required and the transmittance of the lens needs to be maintained high. In this case, the thickness of the hydrophilic film is preferably 5 nm to 50 nm, more preferably 10 nm to 30 nm, and preferably 20 nm. Here, when the thickness of the hydrophilic film is less than 5 nm, the adhesiveness of the hydrophilic film to the lens surface (hereinafter, may be referred to as a lens surface including the lens surface and the back surface of the lens) formed by forming the antireflection film. On the other hand, if the thickness of the hydrophilic film exceeds 50 nm, the transmittance of the lens is lowered and the visibility is deteriorated.

Further, such a hydrophilic film is preferably a material having a low refractive index and a low reflectance, and is preferably formed over the entire back surface of the lens, but may be formed only partially.

Further, the hydrophilic film has an antireflection film in the paint (solution) forming the hydrophilic film, for example, with or without masking by taping, and with or without using a lens holder for film formation. It can also be formed by a dipping method in which the formed lens is immersed, spraying, vapor deposition, or the like. In particular, in the dipping method, when a hydrophilic film made of a material having an OH group (for example, an acrylic polymer resin) is formed on a glass lens made of quartz, silica glass or the like, the OH group and hydrophilicity on the glass surface at the time of immersion are formed. It is beneficial because the film thickness can be easily controlled by the chemical bond with the OH group of the film.

Further, in the present invention, the hydrophilic film is not formed directly on the lens surface, but the antireflection film is interposed between the lens surface (the back surface of the lens) and the hydrophilic film, so that the hydrophilic film with respect to the lens surface is interposed. Can contribute to the improvement of adhesion. That is, in general, when a hydrophilic film is formed directly on the lens surface, it is necessary to match the composition of the entire hydrophilic film with that of the lens in order to improve the adhesion between the lens surface and the hydrophilic film, which is troublesome. In addition to this, although it is costly, when a hydrophilic film is formed on the lens surface via an antireflection film as in the present invention, SiO _2, which is a general component of the antireflection film, is hydrophilic with the antireflection film. Since it is present at the interface with the film, the compatibility between the hydrophilic film and the antireflection film is good, and therefore, the composition for improving the adhesion only at the interface between the antireflection film and the glass surface. All you have to do is modify it. Therefore, the same adhesive force can be stably realized by always using the hydrophilic film with the same specifications without much labor and cost.

In the above configuration, the hydrophilic film is a thin film having hydrophilicity, and the contact angle of water droplets with the hydrophilic film is 40 degrees or less. On the other hand, the water-repellent film is a thin film having water repellency, which means that the contact angle of water droplets with the water-repellent film is 90 degrees or more, and is distinguished from the hydrophilic film in this respect. In this case, the contact angle shall be measured by the intravenous drop method (A, half-angle, Method), and the lens surface on which the film is formed is 2.5 microliters so as not to be affected by the lens surface. Water droplets are dropped, and the curved surface connecting the left and right end points of the droplets is regarded as a straight line, and the contact angle of the water droplets is measured.
Further, in the above configuration, the antireflection film means a film having a function of suppressing the reflectance when the film is formed on the lens surface as compared with the case where the film is not formed on the lens surface.

Further, in the above configuration of the present invention, it is preferable that the hydrophilic film is also formed on the antireflection film on the lens surface.

According to such a configuration, the water droplets adhering to the lens surface exposed on the object side spread on the hydrophilic film to form a thin water film and do not stay on the lens surface. Therefore, it is possible to prevent a decrease in visibility. Further, as described above, since the thickness of the hydrophilic film is set as thin as 50 nm or less, not only the decrease in visibility can be prevented, but also the decrease in the transmittance of the lens due to the formation of the hydrophilic film can be suppressed (transmittance). Can be kept high).

Further, in the above configuration of the present invention, it is preferable that the hydrophilic film is formed over the entire peripheral surface of the lens.

In this way, if the hydrophilic film is formed over the entire peripheral surface of the lens including the peripheral side surface of the lens having no optical characteristics, not only the above-mentioned effects can be obtained, but also the above-mentioned dipping method can be used for one treatment. Since the film formation can be completed with the above method, the number of steps can be reduced (for example, the labor of performing masking or the like can be omitted), and the film formation cost can be reduced.

Further, in the above configuration of the present invention, it is preferable that the hydrophilic film is formed of an acrylic polymer resin.

According to such a configuration, a hydrophilic film is formed of an acrylic polymer resin having a small refractive index and a low reflectance of 2% or less, so that visibility due to fogging on the lens surface and retention of adhered water droplets is obtained. It is possible to maintain a high transmittance of the lens while preventing a decrease.

Further, in the above configuration of the present invention, the lens surface is formed to be convex toward the object side, the back surface of the lens is formed to be recessed toward the inside of the lens, and the hydrophilic film is formed at least in the substantially central region of the back surface of the lens. It is preferable that the lens is used.

In this way, the lens shape is formed so that the front surface of the lens is convex toward the object and the back surface of the lens is recessed toward the inside of the lens. Since the change is likely to be large and fogging is likely to occur, for example, if a hydrophilic film is provided only in this central region, fogging can be efficiently suppressed while suppressing the film formation cost, which is beneficial.

Further, in the above configuration of the present invention, it is preferable that the first lens is a glass lens.

According to such a configuration, since the first lens is a glass lens, as described above, there is an advantage that the film thickness of the hydrophilic film can be easily controlled at the time of film formation by the dipping method under certain conditions.

Further, the camera module according to the present invention is characterized by including the lens unit.
With such a configuration, the effects of the lens unit described above can be obtained with the camera module.

According to the present invention, since the hydrophilic film is formed on the back surface of the lens, it is possible to contribute to anti-fog on the back surface of the lens, and therefore, it is possible to prevent a decrease in visibility. Further, since the thickness of the hydrophilic film is set as thin as 50 nm or less, it is possible not only to prevent fogging but also to suppress a decrease in the transmittance of the lens due to the formation of the hydrophilic film (the transmittance can be maintained high). Furthermore, instead of forming a hydrophilic film directly on the lens surface, an antireflection film is interposed between the lens surface (the back surface of the lens) and the hydrophilic film, which improves the adhesion of the hydrophilic film to the lens surface. Can contribute.

It is the schematic sectional drawing of the lens unit which concerns on 1st Embodiment of this invention. FIG. 3 is an enlarged cross-sectional view of a main part of the lens with a film of FIG. It is the schematic sectional drawing of the camera module which concerns on 1st Embodiment. It is the schematic sectional drawing of the lens unit which concerns on 2nd Embodiment of this invention. FIG. 6 is an enlarged cross-sectional view of a main part of the lens with a film of FIG. It is the schematic sectional drawing of the camera module which concerns on 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The lens unit including the lens with a film of the present embodiment is particularly for a camera module such as an in-vehicle camera. For example, it is fixedly installed on the outer surface side of an automobile, and wiring is drawn into the automobile. Connected to a display or other device. Further, in FIGS. 1 to 6, hatching is omitted for a plurality of lenses.

1 and 2 show a lens unit according to the first embodiment of the present invention. As shown in FIG. 1, the lens unit 11 of the present embodiment includes a cylindrical lens barrel 12 and a plurality of (for example, five) lenses 13, 14, 15, 16, arranged in the lens barrel 12. 17 and two drawing members 22a and 22b are provided. An in-vehicle camera including the lens unit 11 includes a lens unit 11, a substrate having an image sensor (not shown), and an installation member (not shown) for installing the substrate in a vehicle such as an automobile.

The plurality of lenses 13, 14, 15, 16, and 17 fixed and supported by the lens barrel 12 are arranged in a state in which their respective optical axes are aligned with each other, and each lens is arranged along one optical axis O. 13, 14, 15, 16 and 17 are arranged side by side to form a group of lenses used for imaging. The first lens 13 provided at the end (opening) of the lens barrel 12 on the object side is a lens 13 with a film as described later. In the following, the first lens 13 may be referred to as a lens with a film 13.

Of the two diaphragm members 22a and 22b, the first diaphragm member 22a from the object side is arranged between the second lens 14 and the third lens 15 from the object side. The second aperture member 22b from the object side is arranged between the third lens 15 and the fourth lens 16 from the object side. The diaphragm members 22a and 22b are an "aperture diaphragm" that limits the amount of transmitted light and determines an F value that is an index of brightness, or a "light-shielding diaphragm" that blocks light rays that cause ghosts and light rays that cause aberrations. ..

A caulking portion 23 is provided at the end portion (upper end portion in FIG. 1) of the lens barrel 12 on the object side, and the end portion is crimped to the inner diameter side. It is fixed to the end of 12 on the object side. The lens body other than the film of the lens 13 with a film is a glass lens, but a resin lens may be used.

Further, a flange portion 24 having an opening having a diameter smaller than that of the lens 17 is provided at an end portion (lower end portion in FIG. 1) of the lens barrel 12 on the image plane side. The flange portion 24 and the caulking portion 23 hold a plurality of lenses 13, 14, 15, 16, 17 and diaphragm members 22a, 22b forming a lens group in the lens barrel 12. The fixing of the lens 13 with a film is not limited to the caulking portion 23, and the fixing portion attached to the end portion of the lens barrel 12 on the object side after the lenses 13, 14, 15, 16 and 17 are stored in the lens barrel 12. May be done by.

On the outer peripheral surface of the lens 13 with a film located closest to the object, a reduced diameter portion having a smaller diameter is provided on the image surface side portion of the lens 13 with a film, and the reduced diameter portion is an O-ring as a sealing member. 26 is provided, and the outer peripheral surface of the lens 13 with a film and the inner peripheral surface of the lens barrel 12 are sealed by the object-side end of the lens barrel 12. This prevents fine particles such as water and dust from entering the lens barrel 12 from the end of the lens unit 11 on the object side. A cylindrical inner wall 12b is provided inside the lens barrel 12 on the object side, an annular body 27 is provided between the inner wall 12b and the outer wall 12a, and the O-ring 26 is in close contact with the annular body 27. There is.

The inner diameter of the lens barrel 12 gradually decreases from the object side to the image plane side. Correspondingly, the outer diameters of the lenses 13, 14, 15, 16 and 17 become smaller from the object side toward the image plane side. Basically, the outer diameters of the lenses 13, 14, 15, 16 and 17 are substantially equal to the inner diameters of the portions of the lens barrel 12 on which the lenses 13, 14, 15, 16 and 17 are supported. .. On the outer peripheral surface of the lens barrel 12, a flange portion 25 used when the lens barrel 12 is installed on the vehicle-mounted camera is provided on the outer peripheral surface of the lens barrel 12 in a flange shape.

Further, as shown in FIGS. 1 and 2, the lens 13 with a film provided at the end of the lens barrel 12 on the object side has a lens surface 13a facing the object side and a lens back surface 13b facing the image surface side. .. In particular, in the present embodiment, the lens 13 with a film is formed so that the lens surface 13a is convex toward the object side and the lens back surface 13b is recessed toward the inside of the lens in cross-sectional view.

_{Further, the film-attached lens 13 has an antireflection film (AR coating: generally including SiO 2} ) 30 over the entire surface (or at least a part) on the lens surface 13 and the lens back surface 13b excluding the peripheral side surface 13c. Is formed. Further, on the back surface 13b of the lens, a hydrophilic film 31 is formed on the antireflection film 30 with a thickness of 50 nm or less. In this case, the thickness of the hydrophilic film 31 is preferably 5 nm to 50 nm, more preferably 10 nm to 30 nm, and preferably 20 nm. Here, if the film thickness of the hydrophilic film 31 is less than 5 nm, the adhesion of the hydrophilic film 31 to the lens back surface 13b forming the antireflection film 30 is not stable, while the film thickness of the hydrophilic film 31 is 50 nm. If it exceeds, the transmittance of the lens 13 with a film decreases and the visibility deteriorates. As the antireflection film 30, for example, a multilayer film structure is adopted in the present embodiment. In such a multilayer structure, the bottom layer in direct contact with the lens surface (for example, glass) is one of Al ₂ O ₃ , Ta ₂ O ₅ , or SiO _{2, and SiO 2 is placed on the bottom layer. It is preferable that one pair of two} layers and _{five layers of Ta 2} O are stacked one above the other, and a maximum of ten pairs are stacked one above the other, and the specified specifications (that is, in which wavelength range and how much reflectance or less are used). Is determined based on.

Further, such a hydrophilic film 31 is preferably a material having a low refractive index and a low reflectance. In particular, in the present embodiment, the hydrophilic film 31 is formed of an acrylic polymer resin having a small refractive index and a low reflectance of generally 2% or less. In this case, the hydrophilic film 31 is preferably formed over the entire back surface of the lens 13b, but may be formed over only a part of the back surface of the lens. In particular, when the central region R of the back surface 13b of the lens becomes thin as in the lens 13 of the present embodiment, for example, the hydrophilic film 31 may be provided only in this central region R. Will be described later).

Further, the hydrophilic film 31 is anti-reflection in a paint (solution) forming the hydrophilic film 31 with or without masking by taping, and with or without a lens holder for film formation. It can also be formed by a dipping method in which the lens 13 on which the film 30 is formed is immersed, spraying, vapor deposition, or the like. In particular, in the dipping method, when the hydrophilic film 31 made of an acrylic polymer resin is formed on the glass lens 13 made of quartz, silica glass or the like, the OH group on the glass back surface 13b and the OH group of the hydrophilic film 31 at the time of immersion are used. It is beneficial because the film thickness can be easily controlled by the chemical bond of.

FIG. 3 is a schematic cross-sectional view of the camera module 300 of the present embodiment. As shown in FIG. 3, the camera module 300 includes a lens unit 11 to which the filter 100 is mounted.
The camera module 300 includes an upper case (camera case) 301, which is an exterior component, and a mount (flange, pedestal) 302 that holds the lens unit 11. Further, the camera module 300 includes a seal member 303 and a package sensor (image sensor) 304.

The upper case 301 is a member that exposes the end portion of the lens unit 11 on the object side and covers the other portion. The mount 302 is arranged inside the upper case 301 and has a female screw 302a that is screwed with the male screw 11a of the lens unit 11. The seal member 303 is a member inserted between the inner surface of the upper case 301 and the outer peripheral surface 12a of the lens barrel 12 of the lens unit 11, and is a member for maintaining the airtightness inside the upper case 301. ..

The package sensor 304 is arranged inside the mount 302 and is arranged at a position where it receives an image of an object formed by the lens unit 11. Further, the package sensor 304 includes a CCD, CMOS, and the like, and converts the light collected through the lens unit 11 and reached into an electric signal. The converted electrical signal is converted into analog data or digital data, which are components of image data captured by the camera.

As described above, according to the present embodiment, since the hydrophilic film 31 is formed on the back surface 13b of the lens (on the antireflection film 30), fine water droplets adhering to the back surface 13b of the lens are formed on the back surface of the lens 13b. It spreads to form a thin water film and does not stay on the back surface 13b of the lens. This can contribute to the anti-fog of the back surface 13b of the lens, and therefore, the deterioration of visibility can be prevented.

Further, according to the present embodiment, since the thickness of the hydrophilic film 31 is set as thin as 50 nm or less, not only the fogging is prevented but also the decrease in the transmittance of the lens 13 due to the formation of the hydrophilic film 31 is suppressed. Can (maintain high transmittance). This is particularly useful when used in an in-vehicle camera where high visibility is required and the transmittance of the lens needs to be maintained high.

Further, according to the present embodiment, the hydrophilic film 31 is not formed directly on the back surface 13b of the lens, but the antireflection film 30 is interposed between the back surface 13b of the lens and the hydrophilic film 31. It can contribute to the improvement of the adhesion of the hydrophilic film 31 to the back surface 13b. That is, in general, when the hydrophilic film 31 is formed directly on the back surface 13b of the lens, the composition of the entire hydrophilic film 31 is adjusted to that of the lens 13 in order to improve the adhesion between the back surface 13b of the lens and the hydrophilic film 31. Although it is necessary, time-consuming, and costly, when the hydrophilic film 31 is formed on the back surface 13b of the lens via the antireflection film 30 as in the present embodiment, the antireflection film 30 is generally used. _{Since SiO 2,} which is a major component, is interposed at the interface between the antireflection film 30 and the hydrophilic film 31, the compatibility between the hydrophilic film 31 and the antireflection film 30 is good, and therefore, the antireflection film 30 It is only necessary to modify the composition for improving the adhesion only at the interface between the glass surface (the back surface 13b of the lens 13 of the lens 13) and the glass surface (the back surface 13b of the lens 13). Therefore, the same adhesive force can be stably realized by always using the hydrophilic film 31 with the same specifications without much labor and cost.

Further, according to the present embodiment, since the hydrophilic film is formed of the acrylic polymer resin having a small refractive index and a low reflectance of 2% or less, it is accompanied by cloudiness on the back surface 13b of the lens and retention of adhered water droplets. It is possible to maintain a high transmittance of the lens while preventing a decrease in visibility.

Further, in the present embodiment, as described above, it is beneficial to provide the hydrophilic film 31 only in the central region R of the lens back surface 13b, which is thin. This is because the lens 13 is formed so that the front surface 13a of the lens is convex toward the object side and the back surface 13b of the lens is recessed toward the inside of the lens. This is because, for example, if the hydrophilic film 31 is provided only in the central region R, the fogging can be efficiently suppressed while suppressing the film forming cost because the temperature change tends to be large and the fogging is likely to occur.

Further, in the present embodiment, since the lens 13 with a film is a glass lens, as described above, there is an advantage that the film thickness of the hydrophilic film 31 can be easily controlled at the time of film formation by the dipping method under certain conditions. ..

4 and 5 show the lens unit 11A according to the second embodiment of the present invention. Further, FIG. 6 is a schematic cross-sectional view of the camera module 300A including the lens unit 11A of the second embodiment. As shown in these figures, the lens unit 11A of the present embodiment differs only in the form of forming the hydrophilic film 31 from that of the first embodiment, and other configurations are the same as those of the first embodiment. Therefore, in the following, only the parts different from those of the first embodiment will be described, and the same reference numerals will be given to the drawings for the other parts, and the description thereof will be omitted.

As shown in FIGS. 4 and 5, in the present embodiment, the hydrophilic film 31 is formed on the antireflection film 30 on the lens surface 13a in addition to the lens back surface 13b of the lens with film 13. In particular, in the present embodiment, the hydrophilic film 31 is formed over the entire peripheral surface of the lens 13, including the peripheral side surface 13c of the lens 13. In this case, the antireflection film 30 is not formed on the peripheral side surface 13c, and the hydrophilic film 31 is formed directly on the peripheral side surface 13c of the lens 13.

As described above, if the hydrophilic film 31 is also formed on the antireflection film 30 on the lens surface 13a, the following effects can be obtained in addition to the effects of the first embodiment described above. That is, the water droplets adhering to the lens surface 13a exposed on the object side spread on the hydrophilic film 31 to form a thin water film, and do not stay on the lens surface 13a. Therefore, it is possible to prevent a decrease in visibility. Further, also in this case, since the thickness of the hydrophilic film 31 is set as thin as 50 nm or less, not only the decrease in visibility can be prevented, but also the decrease in the transmittance of the lens 13 due to the formation of the hydrophilic film 31 can be suppressed (transmittance). Can be kept high).

Further, in the present embodiment, since the hydrophilic film 31 is formed over the entire peripheral surface of the lens 13 including the peripheral side surface 13c of the lens 13 having no optical characteristics, the dipping method described above can be used for a single process. The film (formation of the hydrophilic film 31) can be completed, and therefore, the number of steps can be reduced (for example, the trouble of performing masking or the like can be omitted), and the film forming cost can be reduced.

Further, if the hydrophilic film 31 is formed over the entire peripheral surface of the lens 13 in this way, the hydrophilic film 31 is also provided on the surface radially inside the portion of the lens 13 with which the caulking portion 23 contacts. Therefore, water droplets do not stay on the step generated between the caulking portion 23 and the outer peripheral edge portion of the lens surface 13a. Therefore, it is possible to prevent a decrease in visibility due to such retention.

In the present invention, the shapes of the lens, the housing, and the like are not limited to the above-described embodiments. Further, the material of the antireflection film, the material of the lens, and the like can be arbitrarily set. Further, the film thickness of the hydrophilic layer can be arbitrarily set as long as it is 50 nm or less.

11,11A Lens unit 12 Lens barrel 13 Lens with film (1st lens)
13a Lens front surface 13b Lens back surface 30 Antireflection film 31 Hydrophilic film 300 Camera module

Claims (7)

A lens unit including a lens group in which a plurality of lenses are arranged along the optical axis of the lens and a lens barrel in which the lens group is housed.
The first lens on the object side of the lens group is provided at the end of the lens barrel on the object side, and has a lens surface facing the object side and a lens back surface facing the image plane side. An antireflection film is formed on the upper surface and the back surface of the lens.
A lens unit characterized in that a hydrophilic film is formed on the antireflection film on the back surface of the lens. The lens unit according to claim 1, wherein the hydrophilic film is also formed on the antireflection film on the lens surface. The lens unit according to claim 2, wherein the hydrophilic film is formed over the entire peripheral surface of the first lens. The lens unit according to any one of claims 1 to 3, wherein the hydrophilic film is formed of an acrylic polymer resin. The lens surface is formed to be convex toward the object side, the back surface of the lens is formed to be recessed toward the image surface side, and the hydrophilic film is formed at least in a substantially central region of the back surface of the lens. The lens unit according to any one of claims 1 to 4, which is characterized. The lens unit according to any one of claims 1 to 5, wherein the first lens is a glass lens. A camera module comprising the lens unit according to any one of claims 1 to 6.

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