Patent Application
20230323523
Various aspects of the present disclosure relate to methods and systems for forming a blade for a shaving device. More particularly, the present disclosure describes embodiments of systems and methods for depositing a lubricating material on an edge of a blade for a shaving device, for example, by thermal evaporation. The present disclosure may apply to a manual shaver, and may also apply to an electric shaver, for example, a wet electric shaver.
Razor blades in a shaver are unique cutting tools due to their unique function, among cutting tools, of cutting hair sticking out from the skin. Such cutting action is different from the one of other cutting tools, which requires razor blades to be designed with some specific functionalities.
Many shavers include one or more razor blade(s) with a polymer coating on a portion of the blade, for example, a razor blade edge. The coating, which may be formed of polytetrafluoroethylene (“PTFE”), often helps to lubricate the shaver, for example, helping to minimize the force needed to cut hair and/or helping to reduce friction between the blade(s) and the user's face. The coating is often deposited on the razor blade, for example, via sublimation, electrophoresis, spraying, or dipping. In one embodiment, the coating is applied by spraying coating, which involves PTFE nanoparticles being dispersed in water to form a stable aqueous dispersion. The aqueous dispersion is then spayed on the edges of the blades. However, spray coating often leads the thickness not being uniform, which may be detrimental to shaving performance.
Other methods may apply thin and uniform films PTFE on blade edges. For example, plasma polymerization, chemical vapor deposition, or physical vapor deposition by high frequency magnetron sputtering may be used to apply PTFE. However, while these techniques could lead to thin PTFE films on blade edge, the structure of the film is not the desirable. A film produced by these mechanisms often has a high hardness, for example, due to crosslinking, which may lead to a greater coefficient of friction compared to bulk-like PTFE. As mentioned above, greater friction is not desirable for shaving.
Accordingly, existing coating processes often yield a coating on the razor blade that does not have a uniform thickness, that has an undesirable hardness (e.g., due to cross-linking) which may increase the friction between the razor blade and the skin, and/or that may otherwise not be desirable for a shaver.
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to being prior art, or suggestions of the prior art, by inclusion in this section.
Aspects of the disclosure include:
A method of forming a coating on a blade for a shaver, the method comprising: a first step of evaporating a portion of a supply of a lubricating coating material in a negative pressure chamber, wherein the blade is positioned in the negative pressure chamber adjacent to the supply of the lubricating coating material such that the portion of the lubricating coating material evaporates from the supply and coats the blade; a second step, performed after the first step, of sintering the portion of the lubricating coating material coating the blade by heating the blade to a temperature above the melting temperature of the lubricating coating material; and a third step, performed after the second step, of cooling the blade after sintering to a room temperature.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and, together with the description, serve to explain the principles of the disclosure. There are many aspects and embodiments described herein. Those of ordinary skill in the art will readily recognize that the features of a particular aspect or embodiment may be used in conjunction with the features of any or all of the other aspects or embodiments described in this disclosure. Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:
The present disclosure relates to methods and systems for coating one or more razor blades for use in a shaver, particularly for coating the one or more razor blades with a lubricating coating.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed. As used herein, the terms “comprises,” “comprising,” or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus. Additionally, the term “exemplary” is used herein in the sense of “example,” rather than “ideal.” It should be noted that all numeric values disclosed or claimed herein (including all disclosed values, limits, and ranges) may have a variation of +/−10% (unless a different variation is specified) from the disclosed numeric value. Moreover, in the claims, values, limits, and/or ranges means the value, limit, and/or range+/−10%. Furthermore, the terms “about” or “approximately” are defined herein as encompassing a variation of +/−10% from the disclosed numeric value (unless a different variation is specified).
Embodiments of the present disclosure related to methods and systems for forming one or more blades for a shaver. The methods and systems disclosed herein may help to form one or more blades with a coating of a lubricating material. The methods and systems disclosed herein may help to form a thin and uniform coating of the lubricating material on the one or more blades. In at least some embodiments, the present disclosure can result in (1) a thin lubricating coating achieved in lower pressure conditions and under a less complex thinning process, for example compared to a process using a solvent, and (2) a thin coating that is suitable for blades used in shaving contributing enhanced shaving performance, where this coating is achieved after applying sintering and cooling steps that optimize the coating properties. Consistent with this, in at least some embodiments, no solvent is used in the manufacturing process. For example, the resulting coating on a razor blade may be a coating of fluoro-containing polymer that is thin and uniform, and that has the same or similar properties as bulk-like properties of the fluoro-containing polymer. An exemplary method may include thermal evaporation of fluoro-containing polymer powder conducted in a vacuum or negative pressure chamber and induced by a power supply that applies voltage at the evaporation temperature of the fluoro-containing polymer on a boat comprising the fluoro-containing polymer powder; and sintering of the blades bearing the evaporated fluoro-containing polymer at temperature above the melting point of the fluoro-containing polymer and subsequent cooling to room temperature with a controlled cooling rate. The sintering means in particular the heating of the deposited polymeric substance, for example particles, at a specific temperature, higher than the melting temperature, for a specific time to allow the film formation and good adhesion onto the razor blade. More specifically, the step of sintering does not include pressure implementation. For example, for PTFE as fluoro-polymer the sintering is related with the melting point of PTFE that ranges from approximately 323 to approximately 327 degrees Celsius and is dependent on the molecular weight. In other words, the step following the aforementioned step of thermal evaporation of fluoro-containing polymer powder is a heating step named “sintering”, where the fluoro-containing polymer undergoes heating at a specific temperature higher than the melting temperature, more specifically while no pressure is applied. According to an embodiment, the sintering occurs in 1-40 degrees Celsius above the melting temperature, more specifically in 10-30 degrees Celsius above the melting temperature.
In step 202, blades 16 may be placed under a vacuum or a negative pressure, for example, at a pressure between approximately 10-1 torr and approximately 10-6 torr, in a negative pressure chamber with a powdered supply of fluoro-containing polymer. The time necessary to reach the desired pressure may depend on the volume of the negative pressure chamber, size and/or specifications of the vacuum pump, etc. The supply of fluoro-containing polymer may be heated such that at least some of the supply of fluoro-containing polymer evaporates. For example, as discussed in greater detail with respect to
As discussed below, a plurality of blades 16 may be stacked or otherwise arranged on a blade holder. The blade holder may be positioned above or otherwise spaced away from the supply of fluoro-containing polymer such that cutting edges of blades 16 are spaced away from the supply of fluoro-containing polymer. The evaporated fluoro-containing polymer may condense or otherwise accumulate on blades 16, for example, on the cutting edges of blades 16. Accordingly, although not shown, method 200 may include an initial step of positioning blades 16 on the blade holder, and positioning the blade holder within the negative pressure chamber. Moreover, the supply of fluoro-containing polymer, the voltage applied to the boat, the spacing between the supply of fluoro-containing polymer and the blade holder, and other aspects of step 202 may be modified and/or adjusted depending on the size or number of blades 16, the spacing between the supply of fluoro-containing polymer and blades 16, the time duration of step 202, etc.
Step 204 includes sintering blades 16 coated with the deposited PTFE to a temperature above the melting temperature of the fluoro-containing polymer. Heating may occur above the melting point of the polymer to form a continuous film that is well adhered to the blades. For example, step 204 may include placing blades 16 into a furnace, for example, by placing the blade holder in a furnace. In some aspects, the furnace may be a conveyor furnace. In step 204, the furnace may heat blades 16 and the fluoro-containing polymer to a temperature near or above the melting temperature of fluoro-containing polymer (e.g., from approximately 200 degrees Celsius to approximately 400 degrees Celsius, at or above approximately 300 degrees Celsius, from approximately 330 degrees Celsius to approximately 380 degrees Celsius, at or above approximately 330 degrees Celsius, or at or above approximately 360 degrees Celsius). The furnace may heat blades 16 and the fluoro-containing polymer incrementally or otherwise at a controlled rate. For example, the furnace may heat blades 16 from the initial room temperature (e.g., approximately 20-30 degrees Celsius) to an intermediate temperature from approximately 200 degrees Celsius to approximately 300 degrees Celsius at a rate of from approximately 40 degrees Celsius per minute to approximately 60 degrees Celsius per minute. Then, the furnace may heat blades 16 from the intermediate temperature to a maximum temperature (e.g., from approximately 330 degrees Celsius to approximately 360 degrees Celsius) at a rate of approximately 5 degrees Celsius per minute to approximately 20 degrees Celsius per minute, for example, approximately 10 degrees Celsius per minute.
The furnace may hold blades 16 at the maximum temperature for a period of time (e.g., approximately 1 minute, approximately 2 minutes, approximately 3 minutes, etc., or shorter or longer). Alternatively, the furnace may not hold blades 16 at the maximum temperature, but instead may proceed to step 206. In these aspects, the duration of step 204 may be from approximately 5 minutes to approximately 30 minutes, for example, between approximately 6 minutes and approximately 15 minutes, with the duration of step 204 depending on, for example, the heating rate and the maximum temperature.
Step 206 may occur after step 204 and includes cooling blades 16 coated with the deposited fluoro-containing polymer. Step 206 may be performed in the furnace or another container/area which is configured to control the internal temperature. For example, step 206 may include cooling blades 16 and the deposited fluoro-containing polymer from the sintering temperature to the room temperature. Step 206 may be performed in a hot/cold stage furnace.
Alternatively or additionally, step 206 may include delivering nitrogen atmosphere, for example, to the furnace (e.g., a sintering furnace). Moreover, blades 16 may be positioned on a conveyor within the furnace (e.g., the sintering furnace), and step 206 may include controlling a speed of the conveyor within the furnace.
The cooling may be performed incrementally or otherwise at a controlled rate. For example, step 206 may include cooling from the maximum temperature to the intermediate temperature, for example, a temperature of from approximately 200 degrees Celsius to approximately 300 degrees Celsius, at a rate of between approximately 2 degrees Celsius per minute and approximately 10 degrees Celsius per minute, for example, approximately 5 degrees Celsius per minute. The cooling from the maximum temperature to the intermediate temperature may last from approximately 5 minutes to approximately 30 minutes, and the duration of the cooling from the maximum temperature to the intermediate temperature depends on one or more of the maximum temperature, the intermediate temperature, and/or the cooling rate. Then, step 206 may include cooling from the intermediate temperature (e.g., from approximately 200 degrees Celsius to approximately 300 degrees Celsius) to the room temperature at a rate of approximately 30 degrees per minute, or at a rate of at least 30 degrees per minute (e.g., approximately 40 degrees per minutes, approximately 50 degrees per minute, etc.). In one aspect, step 206 may include cooling from the intermediate temperature to the room temperature at a rate of from approximately 20 degrees Celsius per minute to approximately 40 degrees Celsius per minute. In these aspects, the duration of step 206 may be from approximately 10 to approximately 45 minutes, for example, from approximately 10 to approximately 15 minutes, with the duration of step 206 depending on, for example, the maximum temperature, the intermediate temperature, the room temperature, and/or the cooling rates.
As shown, the sharp or cutting edges 16a of blades 16 may face the supply of PTFE 306 (and may be disposed closer to the supply of fluoro-containing polymer 306 than respective ends of blade 16 that are directly coupled to blade holder 302). In one aspect, boat 304 is electrically connected to a power source 308 via one or more wires or cables 310, and power source 308 may control the temperature of boat 304, for example, to help evaporate solid fluoro-containing polymer 306 to form vapor fluoro-containing polymer 306a. Blade holder 302, blades 16, boat 304, and PTFE 306 may be enclosed in a vacuum or negative pressure chamber 312, for example, with a port 314 fluidly coupled to a vacuum (or negative pressure) pump 316, which may be a mechanical vacuum pump. As shown, power source 308 may be outside/exterior of negative pressure chamber 312, but electrically connected to boat 304 via the one or more cables or wires 310.
As discussed above with respect to
Additionally, although not shown, negative pressure chamber 312 may include a heating source, for example, an infrared heating source or another similar heating mechanism. In this aspect, the steps of method 200 may be performed in negative pressure chamber 312 with the heating source. For example, in this aspect, the evaporation of step 202, along with the heating and cooling of steps 204 and 206, may be performed in the negative pressure chamber with heating. Additionally, in some aspects, cooling step 206 may include the introduction of a cooling source, for example, nitrogen atmosphere.
As shown in
The systems and methods discussed herein may be scalable and may be used for mass production, for example, for forming a large number of blades 16, each of which are coated in fluoro-containing polymer. For example, step 202 may be performed as a batch process in a vacuum or negative pressure chamber with a mechanical vacuum pump, a power source to heat the boat and multiple blade holders 302 may hold a plurality of blades 16 (e.g., blades 16 may be stacked). Blade holders consisting of plurality of blades may be mounted on a rotating rack and may be rotated during evaporation step for achieving a more uniform coating. One or more boats 304 may contain sufficient fluoro-containing polymer 306 to coat all of the plurality of blades 16. The boat and the rotating rack of the blade holders may be enclosed in the vacuum or negative pressure chamber. In another aspect, a single boat 306 may contain sufficient fluoro-containing polymer 306 to coat all of the plurality of blades 16 and may be placed either in the middle of the vacuum chamber or multiple boats may be used in parallel inside the same chamber. Additionally, step 204 and/or step 206 may be performed in a large furnace such that the plurality of blades, along with the deposited fluoro-containing polymer 306, may undergo sintering and then cooling following the conditions described above in the respective processes. In another embodiment, step 202 may be performed in continuous mode using a conveying path for transferring the blade holders 302. After the above step the conveyor may transfer the stack of blades to a belt furnace where step 204 and/or step 206 may be performed following the conditions described above in the respective processes.
Moreover, step 204 and/or step 206 may help to form a thin (e.g., approximately 20 to 80 nm, among other thicknesses) and uniform layer of fluoro-containing polymer, while at the same time having the bulk-like properties of the fluoro-containing polymer, as discussed above. For example, PTFE powder in negative pressure chamber 312 may be heated to the evaporation temperature, for example, induced by power source 308 applying a voltage. A coating of fluoro-containing polymer deposited on cutting edges 16a via evaporation may be thinner than a coating of fluoro-containing polymer applied via spraying. Due to the thinner layer of fluoro-containing polymer, the maximum temperature for melting fluoro-containing polymer may be reduced. Furthermore, the methods discussed herein may help to ensure that the fluoro-containing polymer coating is well-adhered to blade 16, for example, to cutting edge 16a. Moreover, the deposition in step 202 may be performed at less demanding and/or safer pressures, for example, approximately 10-1 torr to approximately 10-2 torr, than other evaporation processes known in the art.
Additionally, the furnace may help to control the heating and cooling, for example, gradually heating and/or cooling and/or controlling the heating and/or cooling profiles. For example, heating blades 16, with the coating of fluoro-containing polymer, to temperatures above the melting temperature of fluoro-containing polymer, and the subsequent cooling, may help to form a thin and uniform layer of fluoro-containing polymer, while maintaining the bulk-like properties, as discussed herein. The heating profile (i.e., the maximum temperature, the heating rate, the total time of the fluoro-containing polymer is heated above approximately 280 degrees, etc.) may affect the final properties of the fluoro-containing polymer coating. For example, the friction and cutting force performance of blade(s) 16 with the fluoro-containing polymer coating after sintering at approximately 330 degrees Celsius may be improved or otherwise demonstrate an improved performance compared to blade(s) 16 with the fluoro-containing polymer coating after sintering at approximately 345 degrees Celsius or at approximately 370 degrees Celsius.
Moreover, slower or more gradual cooling rates (e.g., from approximately 2 degrees Celsius per minute to approximately 5 degrees Celsius per minute) may help to yield thinner and/or more homogenous or otherwise uniform coatings of fluoro-containing polymer compared to more rapid cooling rates (e.g., above approximately 10 degrees Celsius per minute). For example, as shown in
In some aspects, the cooling from the maximum temperature (e.g., approximately 330 degrees Celsius) to approximately 300 degrees Celsius is the most important factor in the crystallization of fluoro-containing polymer, and the final morphology of the fluoro-containing polymer film, and thus the homogeneity and/or crystallinity, which may be observed via X-ray photoelectron spectroscopy analysis, x-ray diffraction, and/or other techniques. For example, slower cooling rates, for example, of approximately 5 degrees Celsius or slower during the cooling step, especially from the maximum temperature (e.g., approximately 330 degrees Celsius) to approximately 300 degrees Celsius, may help to provide thinner and/or more homogeneous coatings, with improved friction and cutting force performance.
The thickness and/or the frictional properties of the final fluoro-containing polymer coating on blade(s) 16, for example, on blade edge(s) 16a, may be controlled by adjusting one or more of the following parameters during the deposition step (e.g., step 202): the molecular weight of fluoro-containing polymer 306, the quantity of fluoro-containing polymer 306 within boat 304, the material of boat 304, the evaporation temperature (e.g., after applying voltage from power source 308), the pressure within negative pressure chamber 312, the duration of the evaporation step, the distance between boat 304 and blade edge(s) 16a. Moreover, the thickness and/or the frictional properties of the final fluoro-containing polymer coating on blade(s) 16, for example, on blade edge(s) 16a, may be controlled by adjusting one or more of the following parameters during the sintering step (e.g., step 204): the maximum temperature for melting fluoro-containing polymer 306, or the hold time/duration at the maximum temperature. Additionally, the thickness and/or the frictional properties of the final fluoro-containing polymer coating on blade(s) 16, for example, on blade edge(s) 16a, may be controlled by adjusting the cooling rate after melting of fluoro-containing polymer 306 (e.g., from the maximum temperature to an intermediate temperature) during the cooling step (e.g., step 206).
Blade(s) 16 with the fluoro-containing polymer coating may help to provide a comfortable and/or easy shaving experience for a user. The fluoro-containing polymer coating may help to reduce the required force, for example, to cut hairs. The fluoro-containing polymer, for example, because of the bulk-like properties, may help to reduce friction forces, for example, between blade(s) 16 and the user's face, while also reducing the required force to cut hair. In some aspects, blade(s) 16 with the fluoro-containing polymer coating as discussed herein may exhibit similar properties as a blade with sprayed PTFE, for example, require exhibit similar cutting and friction forces. However, blade(s) 16 with the fluoro-containing polymer coating as discussed herein may include a thickness of PTFE less than approximately 400 nm, for example, less than approximately 80 nm, with the fluoro-containing polymer coating being uniform, homogenous, etc. As a result, blade(s) 16 with the fluoro-containing polymer coating as discussed herein may provide an improved shaving performance with low cutting and friction forces, for example, improved fluidity. Moreover, in some aspects, using existing special grade PTFE (LW 2120) does not require a new material, but still helps to obtain the above-discussed properties of blade(s) 16 with the fluoro-containing polymer coating.
It should be appreciated that in the above description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this disclosure.
Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the disclosure, and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.
Furthermore, some of the embodiments are described herein as a method or combination of elements of a method that can be implemented by a processor of a computer system or by other means of carrying out the function. Thus, a processor with the necessary instructions for carrying out such a method or element of a method forms a means for carrying out the method or element of a method. Furthermore, an element described herein of an apparatus embodiment is an example of a means for carrying out the function performed by the element for the purpose of carrying out the disclosure.
In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the disclosure may be practiced without these specific details. In other instances, well-known methods, structures, and techniques have not been shown in detail in order not to obscure an understanding of this description.
While there has been described what are believed to be the preferred embodiments of the disclosure, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the disclosure, and it is intended to claim all such changes and modifications as falling within the scope of the disclosure. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present disclosure.
The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other implementations, which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents and shall not be restricted or limited by the foregoing detailed description. While various implementations of the disclosure have been described, it will be apparent to those of ordinary skill in the art that many more implementations and implementations are possible within the scope of the disclosure. Accordingly, the disclosure is not to be restricted except in light of the attached claims and their equivalents.
As is evident from the figures, text, and examples presented above, a variety of embodiments may be contemplated as follows:
1. A method of forming a coating on a blade for a shaver, the method comprising:
2. The method of claim 1, wherein evaporating the supply of the lubricating coating material includes heating the supply of the lubricating coating material by applying a voltage to an evaporation boat containing the supply of the lubricating coating material.
3. The method of claim 1 or claim 2, wherein evaporating the supply of the lubricating coating material includes heating the supply of the lubricating coating material for about 5 minutes to about 30 minutes.
4. The method of any one of claims 1-3, wherein evaporating includes heating the boat to a temperature of about 200 degrees Celsius to about 400 degrees Celsius, specifically 330 degrees Celsius to about 380 degrees Celsius.
5. The method of any one of claims 1-4, wherein sintering includes heating the blade to a temperature of about 200 degrees Celsius to about 400 degrees Celsius, specifically about 330 degrees Celsius to about 380 degrees Celsius.
6. The method of claim 5, wherein sintering the blade to a temperature includes:
7. The method of any one of claim 5 or 6, wherein sintering occurs in 1-40 degrees Celsius above the melting temperature, more specifically in 10-30 degrees Celsius above the melting temperature.
8. The method of any of claims 4-7, wherein cooling the blade includes:
9. The method of any one of the preceding claims, wherein the blade is one of a plurality of blades, and wherein each of the plurality of blades is mounted on a blade holder.
10. The method of claim 9, wherein the blade holder is positioned from about 3 to about 10 cm above the supply of the lubricating coating material in the negative pressure chamber.
11. The method of any one of the preceding claims, wherein evaporating the supply of the lubricating coating material is performed at about 10-1 torr to about 10-6 torr.
12. The method of any one of the preceding claims, wherein sintering and cooling are performed in a furnace.
13. The method of any one of the preceding claims, wherein the lubricating coating material is a polymeric material, more specifically a non-metallic polymeric material.
14. The method of any one of the preceding claims, wherein the lubricating coating material is any fluoropolymer/fluoro-containing polymer, specifically polytetrafluoroethylene.
15. The method of any one of the preceding claims, wherein after cooling, the blade includes a coating of the lubricating coating material having a thickness of about 10 nm to about 400 nm, specifically 20 nm to about 100 nm.
16. The method of any one of the preceding claims, wherein the supply of the lubricating coating material in the negative pressure chamber includes a powder of the lubricating coating material.
17. The method of any one of the preceding claims, wherein after cooling, the blade includes a coating having a F/C ratio greater than about 1.7.
18. The method of any one of the preceding claims, wherein after cooling, the blade includes a coating having a CF2 content greater than about 60%.
19. A blade formed using the method of any one of the preceding claims.
20. A shaving assembly, comprising:
This application is a National Stage Application of the International Application PCT/EP2021/073980, filed on Aug. 31, 2021, now published as WO 2022/049058, and which claims benefit from the U.S. Provisional Patent Application No. 63/074,121, entitled: “METHODS AND SYSTEMS FOR FORMING A BLADE OF A SHAVING DEVICE”, filed on Sep. 3, 2020, its content being incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/073980 | 8/31/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63074121 | Sep 2020 | US |
