KR102719055B1 - A Method for Producing a Coating Lens - Google Patents

Abstract

The present invention relates to a method for manufacturing a coated lens. The method for manufacturing a coated lens includes a step of preparing a lens substrate; a step of cleaning the lens substrate; a step of wiping the surface of the cleaned lens substrate; a step of forming a coating layer by a vacuum deposition method; and a step of curing the coating layer.

Description

{A Method for Producing a Coating Lens}

The present invention relates to a method for manufacturing a coated lens, and more particularly, to a method for manufacturing a coated lens having a plurality of coating layers formed thereon.

A lens, which is an optical means for gathering or dispersing light by refraction, may be made of a transparent material such as glass, or may be made of glass or plastic. Various types of coating layers may be formed on a lens made of such a material to suit the intended use of the lens. For example, an anti-reflection coating layer may be formed on a spectacle lens to prevent glare and ensure a clear field of view. In addition, a camera lens, a lens of an automobile lamp, or a lens of a rearview mirror may need to be appropriately coated depending on the respective usage environment or purpose. Regarding such a coated lens, Patent Publication No. 10-2019-0010221 discloses a hybrid infrared optical lens having ta_c and Y ₂ O ₃ coating thin film layers. In addition, Patent Publication No. 10-2019-0053865 discloses an optical lens including an anti-reflection coating on one of its major surfaces that significantly reduces the reflection of visible light over a wide range of incident angles. In addition, Patent Publication No. 10-2019-0020406 discloses a method for coating sunglasses lenses by vacuum deposition. It is necessary for the lens coating layer to be formed so as to have a function according to the purpose of the lens while not deteriorating the performance of the lens itself. For example, the lens coating layer basically needs to have high transmittance and sufficient strength for a protective function. In addition, it needs to have sufficient resistance to heat shock and chemical resistance depending on the usage environment. However, the prior art does not disclose a method for forming a coating layer of a lens with such characteristics.

The present invention is intended to solve the problems of prior art and has the following objectives.

Prior art 1: Patent publication number 10-2019-0010221 (Korea Institute of Photonics Technology, published on January 30, 2019) Hybrid infrared optical lens with ta-C and Y2O3 coating thin film layer Prior art 2: Patent publication number 10-2019-0053865 (Esilo Anternacional, published on May 20, 2019) Optical lens including anti-reflection coating with multi-angle efficiency Prior art 3: Patent publication number 10-2019-0020406 (Yoo Heung-sang, published on 2019.03.04.) Sunglass lens coating method by vacuum deposition

An object of the present invention is to provide a method for manufacturing a coated lens having thermal shock resistance, weather resistance and fire resistance while forming multiple coating layers by a vacuum deposition method.

According to a preferred embodiment of the present invention, a method for manufacturing a coated lens comprises: a step of preparing a lens substrate; a step of washing the lens substrate; a step of wiping the surface of the washed lens substrate; a step of forming a coating layer by a vacuum deposition method; and a step of curing the coating layer.

According to another suitable embodiment of the present invention, the step of wiping the surface is performed using a cotton cloth, cotton fiber, non-woven fabric, natural fiber or artificial fiber.

According to another suitable embodiment of the present invention, the coating layer is composed of 9 to 12 identical or different material layers.

According to another suitable embodiment of the present invention, the coating layer is composed of multiple layers formed of a material selected from the group consisting of Ti ₃ O ₅ , SiO _{2 ,} MgF ₂ , Al ₂ O ₃ and SiO ₂ /Al ₂ O ₃ .

The method for manufacturing a coated lens according to the present invention prevents a decrease in transmittance of a multi-coating layer and a peeling phenomenon in a humid environment. The method for manufacturing the lens according to the present invention prevents the occurrence of scratches or blemishes due to impact by foreign substances in the usage environment while forming a coating layer having film strength and weather resistance that can be used in an external environment or an extreme environment. The method for manufacturing the lens according to the present invention can be applied to automobile lenses, and preferably, but not limited to, can be applied to coating a camera lens of an autonomous automobile.

Figure 1 illustrates an embodiment of a method for manufacturing a coated lens according to the present invention.
Figure 2 illustrates another embodiment of a method for manufacturing a coated lens according to the present invention.
Figure 3 illustrates an example of a coating layer formed by a manufacturing method according to the present invention.
Figures 4a and 4e illustrate the results of characteristic tests on a coated lens manufactured by a manufacturing method according to the present invention.

Below, the present invention is described in detail with reference to embodiments shown in the attached drawings, but the embodiments are for a clear understanding of the present invention and the present invention is not limited thereto. In the description below, components having the same drawing symbols in different drawings have similar functions and therefore will not be described repeatedly unless necessary for the understanding of the invention, and well-known components will be briefly described or omitted, but they should not be understood as being excluded from the embodiments of the present invention.

Figure 1 illustrates an embodiment of a method for manufacturing a coated lens according to the present invention.

Referring to FIG. 1, a method for manufacturing a coated lens includes a step of preparing a lens substrate (P11); a step of first washing the lens substrate and inspecting centering (P12); a step of wiping the surface of the first washed lens substrate (P13); a step of forming a coating layer by a vacuum deposition method (P15); and a step of curing the coating layer (16).

The lens substrate may be made of glass, synthetic resin, or similar materials depending on the purpose of the lens, and may have various apertures or foci. For example, the lens substrate may be prepared through the processes of substrate material preparation, double-side rough grinding, double-side finishing, and double-side polishing (P11). The refractive index, dimension, focus, curvature, or thickness of the lens substrate may be inspected, and the lens substrate for which the inspection is completed may be subjected to a primary cleaning (P12). The primary cleaning may be performed by fixing each lens to a cleaning holder, and cleaning may be performed using, for example, isopropyl alcohol (IPA), but is not limited thereto, and may be performed using various solutions such as distilled water or ethyl alcohol, and the present invention is not limited thereby. The lens substrate for which the primary cleaning has been performed may be subjected to an appearance inspection, and may be subjected to, for example, a scratch, a blemish inspection, a stain inspection, or various similar appearance inspections. Once the appearance inspection is completed, a centering inspection or a centering inspection may be performed (P12). In the centering inspection process, the pre-blackening immersion dimension or centering position can be set. After that, the outer diameter, eccentricity, step or Sag (Sagittal Height) inspection can be performed on the lens substrate with the centering set. After such inspection is completed, a process of wiping the surface of the lens substrate can be performed (P13). The coating layer formed on the lens substrate can be peeled off in the external environment, and especially in the case of a lens for an automobile camera, the coating layer can be exposed to various external environments and a peeling shape can occur over time. The surface wiping process can have a function of increasing the adhesion characteristics of the coating layer to the lens substrate or the strength of the coating layer. In this way, the process of wiping the coating layer of the lens substrate can have a function of improving the strength characteristics, anti-peeling characteristics or adhesion characteristics of the coating layer. The wiping process can be performed by, for example, a filament, cotton fiber, non-woven fabric, natural fiber or artificial fiber, and can be performed on an acetal jig. Specifically, at least one scrubbing groove corresponding to the surface shape of the lens substrate may be formed on the acetal jig, and a scrubbing material made of a pad-shaped or plate-shaped filament, cotton fiber, non-woven fabric, natural fiber or artificial fiber may be prepared for each scrubbing groove. Then, the lens surface to be coated may come into contact with the scrubbing material to perform a scrubbing process. During the scrubbing process, the lens surface should not be scratched or nicked by the lens material. To this end, the scrubbing material may be made of a soft material having low friction, and isopropyl alcohol, distilled water or various similar liquids capable of reducing the friction coefficient may be used in a state in which the scrubbing material is absorbed. The contact pressure of the lens substrate may be, for example, 1 to 500,000 pa, and the friction coefficient of the scrubbing material may be adjusted to be 0.2 or less. The lens substrate may be rubbed while being rotated, for example, at a speed of 0.01 to 10 (times/sec) or reciprocated at a speed of 0.01 to 10 m/sec. The rubbing process or the wiping process may be performed in various ways and is not limited to the presented embodiments. When the wiping process is completed (P13), an inspection process and a secondary washing process may optionally be performed (P14). The inspection process may be, for example, an appearance inspection process, and the washing may be performed using a washing solution such as isopropyl alcohol. When the washing process is completed, a coating process may be performed (P15). The coating process may be performed by a vacuum deposition method and may be performed in, for example, a vacuum deposition apparatus or a magnetron sputtering apparatus. According to one embodiment of the present invention, the coating layer may be formed of 9 to 12 identical or different material layers. In addition, the coating layer can be formed of a material selected from the group consisting of Ti ₃ O ₅ , SiO _{2 ,} MgF ₂ , Al ₂ O ₃ and SiO ₂ /Al ₂ O ₃ . Depending on the lens structure, the concave surface can be coated and then the block surface can be coated. In this case where both surfaces are coated, one surface can be coated and then spectroscopically measured. Then, the other surface can be coated after being washed with a washing solution such as isopropyl alcohol and dried. For example, the concave surface can be coated, then spectroscopically measured, washed and dried, and then the convex surface can be coated. The coating layer can be composed of a plurality of sub-coating layers, and different sub-coating layers can have the same or different thicknesses. Or, different sub-coating layers can be formed of the same or different materials. Ti ₃ O ₅ , which forms the sub-coating layer, has the advantage of excellent refractive index, and SiO ₂ has the advantage of good transmittance, excellent film strength, and good transmittance. In comparison, MgF ₂ has excellent transmittance but has a disadvantage of peeling at high humidity. In addition, SiO ₂ /Al ₂ O ₃ has excellent transmittance but has a disadvantage of causing stains or absorbance on the coating surface. Therefore, the formation order and thickness of the sub-coating layer can be controlled based on the advantages and disadvantages of each material. For example, the sub-coating layers can be formed in an order such as STSTSTSTATS, where T, S, and A represent Ti ₃ O ₅ , SiO _{2 ,} and Al ₂ O ₃ , respectively. The thickness of each sub-layer can be 20 to 2,000 nm. A plurality of sub-coating layers can be formed in various orders or various thicknesses, and are not limited to the presented embodiments. When a coating layer consisting of 9 to 12 sub-layers is formed in the same manner (P15), the coating lens can be hardened (P16). Curing can be carried out, for example, at a temperature of 120 to 200° C. for 1 to 5 hours. Once this curing process is completed (P16), the coated lens can be post-processed (P17). The post-processing process can include, for example, a process such as surface treatment or drying of the coated lens. Additionally, depending on the type of lens, the coated lens can be subjected to a blackening process.

This process is described below.

FIG. 2 illustrates another embodiment of a method for manufacturing a coated lens according to the present invention.

Referring to FIG. 2, after the coating layer is formed, additional processes may be performed depending on the intended use of the lens. After the coating layer is formed (P15), it may be washed with a cleaning solution such as isopropyl alcohol (P21) and dried. Then, a spectroscopic examination and an initial contact angle examination may be performed, and the water-repellent property may be confirmed by the contact angle examination. After that, the stabilization process of the coated lens may be performed by leaving it for 50 to 100 hours. Then, a bonding process may be performed in the case of a composite lens (P22). Then, a blackening process may be performed for a single-coated lens or a bonded-coated lens (P23). The blackening process may be performed with a material such as Ephora paint or GT7 to form various films capable of preventing diffuse reflection of the lens due to chromatic aberration, spherical aberration, or astigmatism. The blackening material may be performed with various materials having chemical durability and having a transmittance of 0 in the entire wavelength range, and is not limited to the presented embodiments. After the blackening process is completed (P23), a dimensional inspection, a double band inspection, a white spot inspection, or a scratch inspection can be performed, and then the coated lens can be cured as described above (P16). Then, after various inspections such as an outer diameter, an eccentricity, and a coating surface reflection inspection are performed on the cured coated lens, the coating process can be completed. The manufacturing process of the coated lens can be completed through various post-processing processes, and is not limited to the presented embodiments.

Figure 3 illustrates an example of a coating layer formed by a manufacturing method according to the present invention.

Referring to FIG. 3, a plurality of sub-coating layers (CL_1 to CL_N) can be formed on a lens substrate (LB) by a method for manufacturing a coated lens according to the present invention. For example, the sub-coating layers (CL_1 to CL_N) can be formed in an order such as STSTSTSTATS, where T, S, and A represent Ti ₃ O ₅ , SiO _{2 ,} and Al ₂ O _{3 ,} respectively. Each of the sub-coating layers (CL_1 to CL_N) can have a coating thickness of, for example, 200 to 300 (S), 70 to 120 (T), 500 to 700 (S), 15 to 50 (T), 1,200 to 1,500 (S), 120 to 180 (T), 270 to 320 (S), 620 to 700 (T), 70 to 100 (A), 250 to 350 (T), 900 to 980 (S), and the unit is nm. The total coating thickness (L) can be, but is not limited to, 2 to 10 ㎛, preferably 3 to 6 ㎛, and most preferably 4 to 5 ㎛. The coated lens can be manufactured by various methods, and test results for a coated lens manufactured by a manufacturing method according to the present invention are described below.

Figures 4a and 4e illustrate the results of characteristic tests on a coated lens manufactured by a manufacturing method according to the present invention.

In the characteristic test of Fig. 4a, the structure of the coating layer is as follows, the thickness unit is nm, S, T and A represent SiO ₂ , Ti ₃ O ₅ and Al ₂ O _{3 ,} respectively, and are the same in examples 3b to 3e.

(i) Lens material: LaF ₃ glass material

(ii) Sub-coating layer: STSTSTSTATS (11 layers)

(iii) Thickness (nm): A: 70~90; STSTSTST: 3,300~3,500; TS: 1,100 to 1,400

(iv) Thermal shock test: 110℃/2 hours

(v) Acid resistance test: Sulfuric acid solution/left for 2 hours

(vi) Penetration was tested using a Kabas measuring device, and a scratch test was performed by scratching the coating surface with a cutter, and a spot test was performed by applying black paint to the coating surface.

Referring to (a) of Fig. 4a, it can be seen that the coated lens according to the present invention is resistant to thermal shock and has high acid resistance, as shown in the results of the thermal shock and acid resistance tests on the left. In addition, it was confirmed that no scratches occurred and no stains remained when scratched with a cutter. In addition, referring to (b) of Fig. 4a, the X-axis represents wavelength (nm) and the Y-axis represents reflectance (%), respectively, and it can be seen that AOI (Automatic Optical Inspection) = Ravg ≤ 0.8 %, Rabs ≤ 1.0 % at 0 degrees (400 to 700 nm: blue) and 45 degrees (400 to 700 nm); and Ravg ≤ 1.5 %, Rabs ≤ 2.5%.

The characteristic test conditions of Figs. 4b to 4e are as follows, and the test was conducted in the same manner as Fig. 4a.

Figure 4b:

(i) Lens material: FC5 lens from Hoya

(ii) Sub-coating layer: SA1TA2TA3TS (8 layers)

(iii) Thickness (nm): A3: 90 to 120; A2: 250 to 280; A1 450 to 500; TS: 850 to 1,200; T: 80 to 100; S: 1,500 to 2,000

Fig. 4c:

(i) Lens material: TAFD25 lens from Hoya

(ii) Sub-coating layer: STSTSTSTATS (11 layers)

(iii) Thickness (nm): A: 70~90; STSTSTST: 3,300~3,500; TS: 1,100 to 1,400

Fig. 4d:

(i) Lens material: TAC8 lens from Hoya

(ii) Sub-coating layer: STSTSTSTATS (11 layers)

(iii) Thickness (nm): A: 70~90; STSTSTST: 3,300~3,500; TS: 1,100 to 1,400

Figure 4e:

(i) Lens material: FDS18W lens from Hoya

(ii) Sub-coating layer: STSTSTSTATS (11 layers)

(iii) Thickness (nm): A: 70~90; STSTSTST: 3,300~3,500; TS: 1,100 to 1,400

Referring to FIGS. 4b to 4e, as shown in the results of the thermal shock and acid resistance tests on the left, it can be seen that the coated lens according to the present invention is resistant to thermal shock and has high acid resistance. In addition, it was confirmed that no scratches occurred and no stains remained when scratched with a cutter. In the graph on the right, the X-axis represents wavelength (nm), and the Y-axis represents reflectance (%), respectively. It can be seen that AOI (Automatic Optical Inspection) = 0 degree (400 to 700 nm: blue) and 45 degrees (400 to 700 nm) Ravg ≤ 0.8 %, Rabs ≤ 1.0 %; and Ravg ≤ 1.5 %, Rabs ≤ 2.5%.

In each test, the thickness of SiO ₂ and Ti ₃ O ₅ forming the sub-coating layer was controlled, and the thickness of the SiO ₂ and the sub-coating layer, the Ti ₃ O ₅ sub-coating layer, can be appropriately controlled depending on the usage environment. The thickness of each sub-coating layer was controlled so that the thickness ratio was SiO ₂ : Ti ₃ O ₅ = 1,000: 50 to 1,200. As can be seen from the test results, the coated lens manufactured by the method according to the present invention has high resistance to thermal shock, acid resistance, scratches or stains, and thus can be used under harsh outdoor environmental conditions. For example, the coated lens manufactured by the method according to the present invention can be used as an automotive lens, and can be used as a lens for a surveillance camera applied to an autonomous vehicle, but is not limited thereto.

Although the present invention has been described in detail above with reference to the presented embodiments, those skilled in the art will be able to make various modifications and variations without departing from the technical spirit of the present invention by referring to the presented embodiments. The present invention is not limited by such modifications and variations, but is only limited by the claims attached below.

P11: Preparing the Lens Base P12: Cleaning and Centering Inspection
P13: Surface cleaning P14: Washing
P15: Formation of coating layer P16: Curing
P17: Post-processing

Claims (1)

The stage where the lens substrate is prepared;
The stage where the lens material is cleaned;
Step of wiping the surface of the cleaned lens substrate;
A step of forming a coating layer by a vacuum deposition method performed in a vacuum deposition device or a magnetron sputtering device;
A step in which a coated lens is washed with a washing solution and dried;
A step of blackening the coated lens with Ephora paint; and
Including a step of hardening the coating layer,
The surface cleaning step is performed by contacting the lens surface with a scrubbing material made of a pad-shaped or plate-shaped filament, cotton fiber, non-woven fabric, natural fiber or artificial fiber prepared in at least one scrubbing groove corresponding to the surface shape of the lens substrate formed on the acetal jig.
A method for manufacturing a coating lens, characterized in that the coating layer formed by a vacuum deposition method includes a sub-coating layer formed in the order of STSTSTSTATS, where T, S and A represent Ti ₃ O ₅ , SiO ₂ and Al ₂ O _{3 ,} respectively, and the thickness of the coating layer is 3,300 to 3,500 nm for the STSTSTST layer, 70 to 90 nm for the A layer and 1,100 to 1,400 nm for the TS layer.