KR102427084B1 - Light-shielding film for lens of optical device - Google Patents

Abstract

The present invention relates to a light-shielding film, and more particularly, to a light-shielding film for an optical device lens.

Description

Light-shielding film for lens of optical device

The present invention relates to a light-shielding film, and more particularly, to a light-shielding film for an optical device lens.

Starting with the spread of a new concept mobile phone that is a so-called camera phone that is a fusion of digital camera technology and mobile phone technology, recently, smartphones with Internet networking functions have been popularized.

The miniaturization and weight reduction of camera modules such as mobile phone cameras, compact cameras, and video cameras are continuously being made. Accordingly, light blocking members such as shutters, apertures, and spacers, which were mainly made of metal, are being replaced with light polymer films.

Here, the spacer is made by perforating a film in the shape of a donut in order to maintain the distance between a plurality of lenses and to adjust the resolution of the entire lens unit, and is also called IRIS, MASK, or light-shielding film.

The light-shielding property of such a light-shielding film is usually achieved through a light-shielding layer containing a black pigment such as carbon black, and carbon black greatly inhibits the puncture property of the light-shielding film as the particles have a large tendency to agglomerate and form a lump. , there is a problem of causing cracks in the light-shielding layer when punched. In addition, there is a problem in that the light-shielding layer is easily peeled off by weakening the adhesive force of the light-shielding layer.

Accordingly, while having sufficient light blocking properties and low gloss, lens flare, halation and ghosting are further improved, damage is prevented during punching, and it is urgent to improve a light blocking film for optical device lenses with excellent durability. to be.

Unexamined Patent Publication No. 2020-0015121

The present invention has been proposed to solve the above problems, and while having sufficient light blocking properties and low gloss, lens flare, halation, and ghosting are further improved, damage is prevented during punching, and excellent durability An object of the present invention is to provide a light-shielding film for an optical device lens, a lens unit and a camera module having the same.

In order to solve the above problems, the present invention has an optical density of 4.0 or more, and includes a first black colored layer and a second black colored layer that are respectively provided on the main surface side of the film base as a film base and a coating layer, and the film Provided is a light-shielding film for an optical device lens in which the optical density of the substrate is greater than the optical density of each of the first black colored layer and the second black colored layer.

According to an embodiment of the present invention, the optical density of the first black colored layer and the second black colored layer may be the same.

In addition, the thickness of the film substrate may be 6 to 100 μm, and the first black colored layer and the second black colored layer may each independently have a thickness of 0.5 to 10 μm.

In addition, the first black colored layer and the second black colored layer may each contain a black oil-based dye.

In addition, the optical density of the film substrate may be greater than the total optical density of the first black colored layer and the second black colored layer.

In addition, the optical density of the film substrate may be 2 to 13 times the total optical density of the first black colored layer and the second black colored layer.

In addition, the optical density of each of the first black colored layer and the second black colored layer may be less than 1.0.

In addition, the central portion of the light blocking film may be provided with a through hole.

In addition, a primer layer is further included between each of the main surfaces of the film substrate and the first black colored layer and the second black colored layer, and an antistatic layer is further provided on each of the first black colored layer and the second black colored layer. may include

In addition, the present invention provides a lens unit for an optical device comprising a plurality of lenses stacked in the optical axis direction, and the light blocking film according to the present invention disposed at at least one of several points between adjacent lenses.

In addition, the present invention provides a camera module including the lens unit according to the present invention.

According to the present invention, while having sufficient light-shielding properties and low gloss, lens flare, halation, and ghosting are further improved, damage is prevented during punching, and excellent durability, so it can be widely used in optical devices such as camera modules. can

1 is a perspective view of a light-shielding film according to an embodiment of the present invention and a cross-sectional view taken along the boundary line XX'.
2 is a cross-sectional view of a light blocking film according to another embodiment of the present invention.
3 and 4 are flare development photographs of light-shielding films according to Example 1 and Comparative Example 1, respectively.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

Referring to FIG. 1 , the light blocking film 100 according to an embodiment of the present invention includes a film substrate 10 and a first black coloring layer 20 provided on the main surface side of the film substrate 10, respectively. and a second black coloring layer 30 , and is a light-shielding film having an optical density of 4.0 or more.

Here, the optical density is calculated after measuring transmittance according to the definition of ISO 5-1, and as the light transmittance increases, the optical density decreases in inverse proportion. The light-shielding film 100 according to the present invention has an optical density of 4.0 or higher, thereby achieving excellent light-shielding properties. If the optical density is less than 4.0, it may be difficult to apply as a light blocking film for optical equipment lenses due to insufficient light blocking properties.

The light blocking film 100 according to an embodiment of the present invention achieves the above-described optical density through the film substrate 10 , the first black colored layer 20 and the second black colored layer 30 , in which case the film substrate The optical density of (10) is configured to be greater than the optical density of each of the first black coloring layer 20 and the second black coloring layer 30, and through this, the first black coloring layer 20 and the second black coloring layer (30) By improving the adhesive properties between each and the film substrate 10 and preventing damage such as cracking of the black colored layer during punching, there is an advantage that can minimize fluctuations in optical properties due to damage or unintended optical side effects . In other words, in the case of a conventional light-shielding film, the light-shielding property is expressed by increasing the optical density of the light-shielding film coated on the film substrate. However, a large amount of black pigment impairs the adhesive properties with the film substrate, and cracks in the light-shielding film caused by a large amount of black pigment when the light-shielding film is punched and the resulting black pigment powder foreign matter cause unintended optical side effects. Therefore, it may be unsuitable for use as a light-shielding film for optical purposes. Specifically, when visually observing a lens unit employing a light blocking film having cracks, an optical side effect of seeing thread-like burrs around the lens may occur. However, in the light blocking film 100 according to the present invention, the optical density of the film substrate 10 is greater than the optical density of each of the first black colored layer 20 and the second black colored layer 30, so the above-mentioned problems can solve Furthermore, by configuring the film substrate 10 to be greater than the optical density of the first black coloring layer 20 and the second black coloring layer 30, diffuse reflection of light incident from the side of the light-shielding film can be induced. phenomenon can be further minimized.

More preferably, the optical density of the film base 10 may be greater than the total optical density of the first black colored layer 20 and the second black colored layer 30, and more preferably, the optical density of the film base 10 The optical density may be 2 to 13 times, more preferably 2.4 to 13 times, of the total optical density of the first black colored layer 20 and the second black colored layer 30, through which the adhesion of the black colored layer described above The properties are further improved, and it can be more advantageous in preventing damage during punching and at the same time preventing flare. If the optical density of the film substrate 10 is less than twice the total optical density of the first black colored layer 20 and the second black colored layer 30, the optical density of the light-shielding film is low, so that it can function as a light-shielding film. Otherwise, there is a risk of lowering the adhesive strength between the black colored layer and the film substrate and causing damage during punching due to the high optical density of the black colored layer. In addition, there is a possibility that the generated cracks and the like may lead to poor appearance in the process and foreign matter due to the black pigment powder. In addition, if the optical density of the film substrate is 13 times greater than the total optical density of the first black colored layer 20 and the second black colored layer 30, light reflection is increased in the black colored layer, resulting in flare There is a possibility that the phenomenon may occur or aggravate, and the black feeling may be reduced due to a decrease in black brightness.

The film substrate 10 is a support for the light-shielding film and a member that mainly contributes to achieving the optical density of the light-shielding film of the present invention. A material known in the light-shielding film field may be employed, and as an example, PET, PA, PC , PI, PMMA, TAC, etc. may be a film used as a subject. In addition, in order to express a predetermined optical density, a known pigment such as carbon black may be further contained in the same subject as described above.

The film substrate 10 may have a thickness of 6 to 100 μm, more preferably 9 to 50 μm. If the thickness is less than 6㎛, it may be difficult to achieve the desired level of optical density, and if the thickness exceeds 100㎛, it is advantageous to achieve the desired level of optical density of the light-shielding film, but the reflection becomes severe from the side of the film substrate, causing flare There is a risk that the phenomenon may be exacerbated.

The film substrate 10 may be, for example, a PET film containing a pigment, and may have an optical density of 3.0 or more, more preferably 4.0 or more.

In addition, the first black colored layer 20 and the second black colored layer 30 provided on the main surface of the above-described film substrate 10 make the color of the light-shielding film 100 black, and impart matteness, , a layer that assists in light-shielding auxiliary. The black coloring layers 20 and 30 may contain a matrix resin and pigments or dyes dispersed in the matrix resin, and may further contain other additives such as lubricants.

The matrix resin functions to form a coating layer having strong physical properties such as weather resistance, corrosion resistance, and chemical resistance, and a known binder resin for forming the coating layer may be used without limitation. Non-limiting examples of the binder resin include poly(meth)acrylic acid-based resin, polyester resin, polyvinyl acetate resin, polyvinyl chloride, polyvinylbutyral resin, cellulose-based resin, polystyrene/polybutadiene resin, and polyurethane resin. , alkyd resin, acrylic resin, unsaturated polyester resin, epoxy ester resin, epoxy resin, acrylic polyol resin, polyester polyol resin, polyisocyanate, epoxy acrylate-based resin, urethane acrylate-based resin, polyester acrylate-based resin, Polyether acrylate-based resins, phenol-based resins, melamine-based resins, urea-based resins, diallyl phthalate-based resins, and the like may be used alone or in combination of two or more. Preferably, the matrix resin may be a urethane-based resin such as polyurethane.

The pigment or dye is a component that causes the light blocking film 100 to have a black color, and any known pigment or dye that makes the light blocking film 100 appear black may be used without limitation. For example, the pigment may be carbon black, titin black, aniline black, iron oxide, or the like, and the dye may be a black oil-based dye. The content of the pigment or dye may be appropriately adjusted in consideration of the optical density and brightness of the black coloring layer. Preferably, a dye may be provided rather than a pigment, and even if the individual particle size of the pigment is small, they are easily aggregated and agglomerated to form secondary particles, and the formed secondary particles allow the light blocking film to have a predetermined size and shape or through holes In the punching process of forming a black color layer, damage such as cracks may be induced, and there is a risk of lowering the adhesive force with the film substrate. In addition, the case of using a dye is advantageous in securing the adhesion and adhesion between the black coloring layers 20 and 30 and the film substrate 10, and the lubricant or fine particle selection for further lowering the surface reflectance is wide, so that the glossiness is improved. It may be more advantageous to lower it and prevent flaring.

In addition, the black colored layers 20 and 30 may further include a lubricant, and the lubricant may improve the sliding properties of the surfaces of the black colored layers 20 and 30 . On the other hand, the lubricant may be composed of two types of lubricants having different particle diameters, for example, a first lubricant having an average particle diameter of 1 to 5 μm and a second lubricant having an average particle diameter of 6 to 10 μm. . In this case, the first lubricant having a small average particle diameter may impart matte properties to the black colored layers 20 and 30 , and the second lubricant may impart sliding properties to the surfaces of the black colored layers 20 and 30 . The first lubricant and the second lubricant may be mixed in a weight ratio of 1:1.5 to 2.5, and through this, it may be advantageous to achieve a desired effect. The lubricant may be provided in an amount of 10 to 25 parts by weight based on 100 parts by weight of the above-described binder resin, and when it is less than 10 parts by weight, there is a fear that sliding properties may be deteriorated, and when it exceeds 25 parts by weight, the adhesive properties with the film substrate 10 are poor. lowered, and may be a factor causing cracks in the black colored layers 20 and 30 when punched. On the other hand, the lubricant is one of the factors affecting the optical density of the black coloring layers 20 and 30, and the content can be appropriately adjusted in consideration of the content of the aforementioned pigment or dye in order to realize the desired optical density. make it clear

In addition, the lubricant can be used without limitation if it is a known material, and as a non-limiting example, the lubricant is polytetrafluoride (PTFE), polytrifluoride ethylene (PCTFE), polyvinylidene fluoride (PVDF), Polyvinyl fluoride (PVF), polyethylene tetrafluoride copolymer (ETFE), etc. may be used.

In addition, the first black colored layer 20 and the second black colored layer 30 may each independently have a thickness of 0.5 to 10 μm, preferably 1 to 10 μm, and in this case, the first black colored layer 20 ) and the thickness of the second black coloring layer 30 may be the same or different from each other.

In addition, the above-described first black coloring layer 20 and the second black coloring layer 30 may have the same optical density or may be implemented differently. In this case, the optical concentrations of the first black colored layer 20 and the second black colored layer 30 may each independently be less than 1.0, and in another example, 0.15 or more and less than 1.0. If the optical density of the first black colored layer and/or the second black colored layer is 1.0 or more, light blocking properties may be improved, but damage such as cracks may occur during punching, and peeling between the film substrate and the black colored layer may occur.

On the other hand, when described with reference to FIG. 2 , the light-shielding film 100 ′ is a film substrate 10 in order to strengthen the adhesive properties between the film substrate 10 and the first black colored layer 20 and the second black colored layer 30 . A primer layer 40 may be further included thereon, and a first black colored layer 20 and a second black colored layer 30 may be provided on the primer layer 40 . The primer layer 40 may be used without limitation in the case of a known primer layer material, and may be preferably selected in consideration of the material of the matrix resin of the black coloring layers 20 and 30 described above. For example, when the matrix resin is a urethane-based resin, the primer layer 40 may also use a urethane-based resin.

The primer layer 40 may have a thickness of 3 μm or less, and when the thickness of the primer layer 40 exceeds 3 μm, when the composition forming the black coloring layers 20 and 30 is applied, an appearance defect due to blocking may occur. and may cause flare due to increased gloss by the transparent primer layer.

In addition, an antistatic layer 50 may be further provided on each of the above-described first black colored layer 20 and second black colored layer 30 . The antistatic layer 50 may be a coating layer containing a known conductive material and a binder resin. For example, the conductive material may be an alkali metal salt, an ionic liquid, a conductive polymer such as polyaniline, polypyrrole, or polythiophene, or a carbon-based material such as graphene or carbon nanotubes. In addition, the binder resin may include one selected from the group consisting of acrylic resins, urethane-based resins, urethane-acrylic copolymers, ester-based resins, ether-based resins, amide-based resins, epoxy-based resins, and melamine resins, or a mixture thereof. However, the present invention is not limited thereto. The antistatic layer 50 may have a thickness of 10 nm to 400 nm or less, but is not limited thereto.

On the other hand, the above-described light blocking film 100 may include a through hole in the central portion. The through hole functions as a passage through which light passes through a lens or the like. The through hole may be performed through a conventional punching process for the film member.

In this case, a flare phenomenon due to reflection of light may occur on the inner wall of the light blocking film 100 due to the through hole. In order to prevent this, the inner wall of the light blocking film 100 according to an embodiment of the present invention may be corroded, thereby preventing or minimizing the occurrence of flare by increasing the roughness of the inner wall surface or bending the inner wall inward. can do. The corrosion treatment may be performed through a basic solution, but is not limited thereto.

The above-described light-shielding film implements a lens unit for an optical device together with a plurality of lenses. Specifically, the lens unit may include a plurality of lenses stacked in the optical axis direction and a light blocking film disposed at at least one of several points between adjacent lenses. The specific shape of the lens unit, the number of lenses provided in the lens unit, the type of lens (convex lens, concave lens, aspherical lens, spherical lens, etc.), arrangement of lenses, etc. refer to a conventional lens unit for optical devices. Since it can be suitably modified, the present invention is not particularly limited thereto.

In addition, the above-described lens unit may be implemented as a camera module. The camera module may further include an imaging device such as a CCD image sensor or a CMOS image sensor for imaging a subject through the lens unit, and the imaging device may be disposed on an optical axis of the lens unit.

The present invention will be described in more detail through the following examples, but the following examples are not intended to limit the scope of the present invention, which should be construed to aid understanding of the present invention.

<Example 1>

A PET film having a thickness of 25 µm and an optical density of 4.0 was prepared as a film substrate. On both sides of the prepared film substrate, 7 parts by weight of a lubricant (PTFE, consisting of a first lubricant with an average particle diameter of 5 μm and a second lubricant with an average particle diameter of 10 μm in a weight ratio of 1:2) and 1 weight of a black oil-based binder based on 100 parts by weight of a urethane-based binder Each of the black colored layer-forming compositions in which parts and 300 parts by weight of methyl ethyl ketone organic solvent were mixed was microgravure-coated to achieve a final thickness of each black colored layer of 3 μm and an optical density of each black colored layer of 0.36.

Thereafter, the antistatic coating layer-forming composition of the P.E.D.O.T series was coated on each black colored layer to a thickness of 100 nm using a micro-gravure coating method to form an antistatic layer, thereby preparing a light-shielding film for an optical device lens as shown in Table 1 below.

<Examples 2 to 7>

It was prepared in the same manner as in Example 1, except that the optical concentration of the black colored layer and the PET film base and/or the black organic dye in the black colored layer was changed as shown in Table 1 below to prepare a light-shielding film.

<Comparative Example 1>

It was prepared in the same manner as in Example 1, except that the optical density of the black colored layer and the PET film base and the black organic dye in the black colored layer were changed as shown in Table 1 below to prepare a light-shielding film.

<Experimental example>

The following physical properties were evaluated for the light-shielding films prepared in Examples and Comparative Examples, and the results are shown in Table 1 below.

1. Adhesive properties between the black colored layer and the film substrate

The adhesive properties between the black colored layer and the film substrate were evaluated through the cross-cut method. Specifically, after realizing a total of 100 grid patterns by cutting the light-shielding film into a 3 mm grid, the adhesion test tape was placed parallel to the grid pattern and attached. After 3 minutes, the adhesion test tape was uniformly peeled off at a 60 degree angle. . Thereafter, the surface state of the light-shielding film was checked through a magnifying glass and evaluated based on the following criteria.

0: The cut surface is clean and the grid rectangle is not separated.

1: A small piece of the black pigmentation layer is separated at the intersection, and the total area of the separated pieces is less than 5% of the total grid area

2: A small piece of the black coloring layer was separated along the cut intersections and edges, and the total area of the separated pieces was more than 5% to less than 15% of the total grid area

3: The edge of the cut surface of the black colored layer and a part of the rectangle are separated, and the total area of the separated pieces is more than 15% to less than 35% of the total grid area

4: The black pigmentation layer is largely peeled off along the edge of the cut surface, the squares are separated, and the total area of the separated pieces is more than 35% to less than 65% of the total grid area

5: more separated than '4', and the total area of the separated pieces is more than 65% of the total grid area

2. Whether the black pigmented layer is damaged after punching

After piercing the implemented light-shielding film to have an outer diameter of 4.5mm and an inner diameter of 1.5mm, insert it between the optical lenses to realize the lens unit. was observed, and when burrs like yarn were observed, it was indicated by ○, and when no burrs were generated, it was indicated by ×.

3. Evaluation of flare phenomenon

For the flare test, a punched light-shielding film was mounted on the S company's smartphone model, a strong light was given in a dark room with LED lighting, and it was actually photographed depending on the angle, and it was checked whether the flare phenomenon appeared on the photographed image. The case where a flare phenomenon was observed was marked with ○, and the case where no flare phenomenon was observed was marked with ×. In addition, the flare phenomenon of Example 1 and Comparative Example 1 was shown by taking pictures in FIGS. 3 and 4 below.

As can be seen in Figures 3 and 4,

In the case of FIG. 4 photographed in Comparative Example 1, a shower flare through which light flows is observed, but in the case of FIG. 3 photographed in Example 1, it can be seen that shower play is not observed.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 first black colored layer Pigment or dye type black organic dye black organic dye black organic dye black organic dye carbon black black organic dye carbon black carbon black Thickness (㎛) 3 3 3 3 3 3 3 3 optical density 0.36 0.17 0.15 1.12 1.50 0.98 0.96 2.5 film base Thickness (㎛) 25 25 25 25 25 25 25 25 Optical density (A) 4.0 4.0 4.0 4.0 2.5 4.0 4.0 1.2 2nd black colored layer Pigment or dye type black organic dye black organic dye black organic dye black organic dye carbon black black organic dye carbon black carbon black Thickness (㎛) 3 3 3 3 3 3 3 3 optical density 0.36 0.17 0.15 1.12 1.50 0.98 0.96 2.5 First black colored layer + second black colored layer optical density (B) 0.68 0.31 0.29 2.20 2.90 1.95 1.93 4.84 A:B optical density ratio 5.88:1 12.98:1 13.79:1 1.82:1 0.86:1 2.05:1 2.07:1 0.82:1 shading film optical density above 4.0 above 4.0 above 4.0 above 4.0 above 4.0 above 4.0 above 4.0 above 4.0 Properties Adhesive properties 0 0 0 2 3 0 2 5 Damage × × × × ○ × × ○ flare phenomenon × × ○ × ○ × × ○

As can be seen from Table 1,

In the case of Comparative Example 1, the total optical density exceeds 4.0, so there is no problem in the expression of the light-shielding properties, but the first black colored layer or the second black colored layer has a higher optical density than the film base, so the adhesive properties with the film base are poor, and damage during punching This occurs, and it can be seen that a flare phenomenon is also induced.

However, in the case of Example, compared to Comparative Example 1, the adhesive properties were excellent, and it can be seen that less damage occurred during punching. However, in the case of Example 5, in which the optical density of the film base was smaller than the sum of the optical concentrations of the first black colored layer and the second black colored layer, the adhesive properties were lowered and the damage during punching was large compared to other examples, and the flare phenomenon occurred. can be checked

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention can add components within the scope of the same spirit. , changes, deletions, additions, etc. may easily suggest other embodiments, but this will also fall within the scope of the present invention.

100,100': light blocking film 10: film base
20, 30: black tinted layer

Claims (10)

The optical density is 4.0 or higher,
A first black colored layer and a second black colored layer respectively provided on the main surface side of the film base as a film base and a coating layer,
The optical density of the film substrate is greater than the optical density of each of the first black colored layer and the second black colored layer, and the total optical density of the first black colored layer and the second black colored layer. According to claim 1,
The film substrate has a thickness of 6 to 100 μm, and the first black colored layer and the second black colored layer are each independently a light blocking film for an optical device lens having a thickness of 0.5 to 10 μm. According to claim 1,
The first black colored layer and the second black colored layer each contain a black oil-based light-shielding film for an optical device lens. delete According to claim 1,
The optical density of the film base is 2 to 13 times the total optical density of the first black colored layer and the second black colored layer. According to claim 1,
The first black colored layer and the second black colored layer each have an optical density of less than 1.0, a light blocking film for an optical device lens. According to claim 1,
A light blocking film for an optical device lens in which a through hole is formed in the central portion of the light blocking film. According to claim 1,
A primer layer is further included between each of the main surfaces of the film substrate and the first black colored layer and the second black colored layer, and an antistatic layer is further included on each of the first black colored layer and the second black colored layer Light-shielding film for optical equipment lenses. a plurality of lenses stacked in the optical axis direction; and
A lens unit for an optical device comprising a; the light blocking film according to any one of claims 1 to 3 and 5 to 8 disposed at at least one of several points between adjacent lenses. A camera module comprising the lens unit according to claim 9 .

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