Patent Publication Number: US-2022212427-A1

Title: Uv curing apparatus for contact-lens polymerization process

Description:
This application claims priority of Application No. 110100600 filed in Taiwan on 7 Jan. 2021 under 35 U.S.C. § 119; the entire contents of all of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a contact-lens fabrication apparatus, particularly to a UV (ultraviolet) curing apparatus for a contact-lens polymerization process. 
     Description of the Prior Art 
     The contact lenses can replace ordinary eyeglasses to overcome problems of vision. Therefore, the contact lens is a popular option for the persons suffering from visual degradation, such as myopia. The contact lens with a colored annularity around the optical area has become an essential fashion accessory in many countries and thus assumes the position of fashion statement. Some types of contact lenses not only can correct vision but also can present a special style of the users. 
     The fabrication process of contact lenses includes steps of machining, casting, spin-coating, thermal curing/UV curing, etc. Refer to  FIG. 1 . In the conventional technology of fabricating contact lenses, a conveyor  50  is used to convey a receiving disc  52  carrying a plurality of molds  51 ; a contact-lens polymer  53  is injected into the molds  51 ; a plurality of strip-like UV tube lamps  54  is used to illuminate the contact-lens polymer  53 , whereby to cure the contact-lens polymer  53 ; after the molds  51  are split, contact lenses are obtained. In the conventional technology, the UV light is only projected to a single surface of the molds until the whole contact-lens polymer is completely cured, which leads to poor curing effect, different curing extents in different regions of the contact-lens polymer, and poor production efficiency. Further, the uneven curing of the contact-lens polymer is likely to cause instability of the optical region, distorted structure, and cracks, which may seriously affect the yield. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a UV (ultraviolet) curing apparatus for a contact-lens polymerization process, wherein different portions of a UV curing module are respectively arranged above and below mold cavities, and wherein light guide devices are used to let the upper and lower light receiving surfaces of the molds be fully illuminated by the curing light, whereby the contact-lens polymer inside the molds are cured uniformly, and whereby is shortened the curing time, promoted the yield and decreased the fabrication cost. 
     In order to achieve the abovementioned objective, the present invention provides a UV curing apparatus for a contact-lens polymerization process. The UV curing apparatus of the present invention comprises a carrying device, a UV curing module, a first light guide device and a second light guide device. The carrying device includes a plurality of mold cavities. The plurality of mold cavities respectively carries molds. The mold receives a contact-lens polymer. The mold has an upper light receiving surface and a lower light receiving surface. The upper light receiving surface is a planar surface, and the lower light receiving surface is a curved surface. The UV curing module includes a plurality of first UV light sources and a plurality of second light UV light sources. The first UV light sources are arranged above the mold cavities. The second UV light sources are arranged below the mold cavities. The first light guide device includes a plurality of first light output areas. The first light output areas are respectively corresponding to the first UV light sources and disposed between the first UV light sources and the mold cavities, whereby the first light guide device guides the light beams emitted by the first UV light sources to pass through the corresponding first light output areas and illuminate the corresponding upper light receiving surfaces of the molds. The second light guide device includes a plurality of second light output areas. The second light output areas are respectively corresponding to the second UV light sources and disposed between the second UV light sources and the mold cavities, whereby the second light guide device guides the light beams emitted by the second UV light sources to pass through the corresponding second light output areas and illuminate the corresponding lower light receiving surfaces of the molds. 
     According to one embodiment of the present invention, the first light guide device includes a first substrate. A plurality of first light guide holes is formed on the first substrate to function as the first light output areas. The first light guide device constrains the light beams emitted by the first UV light sources to transmit inside the first light guide holes. 
     According to one embodiment of the present invention, the diameter of each of the first light guide holes is gradually decreased from the position near the first UV light sources to the position far away from the first UV light sources. 
     According to one embodiment of the present invention, the first substrate includes a delustering material. In one embodiment, the first substrate is made of a plastic material. Preferably, the first substrate is made of a glass or metallic material coated with a delustering film. 
     According to one embodiment of the present invention, the second light guide device includes a second substrate. A plurality of second light guide holes is formed on the second substrate to function as the second light output areas. The second light guide guide constrains the light beams emitted by the second UV light sources to transmit inside the second light guide holes. 
     According to one embodiment of the present invention, the diameter each of of the second light guide holes is gradually decreased from the position near the second UV light sources to the position far away from the second UV light sources. 
     According to one embodiment of the present invention, the second substrate includes a delustering material. In one embodiment, the second substrate is made of a plastic material. Preferably, the second substrate is made of a glass or metallic material coated with a delustering film. 
     According to one embodiment of the present invention, the first light guide device includes a plurality of light-focusing lenses, which form the plurality of first light output areas. The first light guide device passes the light beams emitted by the first UV light sources through the light-focusing lenses and then vertically projects onto the upper light receiving surface of the mold. 
     Below, embodiments are described in detail to make easily understood the objectives, characteristics and accomplishments of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a conventional UV curing apparatus for contact-lenses. 
         FIG. 2  is a sectional view schematically showing a UV curing apparatus for a contact-lens polymerization process according to a first embodiment of the present invention. 
         FIG. 3  is a sectional view schematically showing a UV curing apparatus for a contact-lens polymerization process according to a second embodiment of the present invention. 
         FIG. 4  is a sectional view schematically showing a UV curing apparatus for a contact-lens polymerization process according to a third embodiment of the present invention. 
         FIG. 5  is a sectional view schematically showing a UV curing apparatus for a contact-lens polymerization process according to a fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Refer to  FIG. 2 .  FIG. 2  is a sectional view schematically showing a UV (ultraviolet) curing apparatus  100  for a contact-lens polymerization process according to a first embodiment of the present invention. In this embodiment, the UV curing apparatus  100  comprises a carrying device  10 , a UV curing module  20 , a first light guide device  30  and a second light guide device  40 . A plurality of mold cavities  11  is intermittently disposed in the carrying device  10 . The mold cavity  11  is a space used to carry a mold  12 . The mold  12  is made of a light-permeable material, such as a PP plastic, allowing the UV ray to pass. The mold  12  includes an upper light receiving surface  121  and a lower light receiving surface  122  opposite to the upper light receiving surface  121 . The upper light receiving surface  121  is a planar surface. The lower light receiving surface  122  is a curved surface. A contact-lens polymer  13  is disposed inside the mold  12 . It is well known by the persons skilled in the art: the contact-lens polymer  13  is a material, which can be polymerized to form a contact lens. The contact-lens polymer  13  may be a hydrophilic monomer (such as Poly ( 2 -hydroxyethyl methacrylate)), a hydrophobic monomer (such as siloxane) or a monomer mixture thereof. The contact-lens polymer  13  may further include another material or component having a special function, such as a photoinitiator, a thermal initiator, or an additive for increasing the hydrophilicity of the contact lens. 
     The UV curing module  20  includes a plurality of first UV light sources  21  and a plurality of second UV light sources  22 . The first UV light sources  21  are arranged above the mold cavities  11  and the second UV light sources  22  are arranged below the mold cavities  11  such that the upper region and the lower region of each mold cavity  11  are substantially corresponding to one first UV light source  21  and one second UV light source  22  respectively. In this embodiment, the first UV light sources  21  and the second UV light sources  22  are light-emitting diodes. Each light-emitting diode is a point light source where brightness is concentrated. 
     The first light guide device  30  includes a plurality of first light output areas  31 . Each first light output area  31  is corresponding to one first UV light source  21  and disposed between the first UV light source  21  and the mold cavity  11 , whereby to guide the light beam emitted by the first UV light source  21  to pass through the corresponding first light output area  31  and illuminate the upper half of the mold cavity  11 , i.e. illuminate the upper light receiving surface  121  of the mold  12 . In this embodiment, the first light guide device  30  includes an opaque first substrate  32  and a plurality of first light guide holes  33 . The first light guide holes  33  form the plurality of first light output areas  31 . The first light guide hole  33  constrains the light beam emitted by the corresponding first UV light source  21  to transmit inside the first light guide hole  33 , whereby the light is concentrated to illuminate the upper light receiving surface  121 , and whereby the upper light receiving surface  121  is exempted from being interfered with by neighboring light sources. 
     The second light guide device  40  includes a plurality of second light output areas  41 . Each second light output area  41  is corresponding to one second UV light source  22  and disposed between the second UV light source  22  and the mold cavity  11 , whereby to guide the light beam emitted by the second UV light source  22  to pass through the corresponding second light output area  41  and illuminate the lower half of the mold cavity  11 , i.e. illuminate the lower light receiving surface  122  of the mold  12 . In this embodiment, the second light guide device  40  includes an opaque second substrate  42  and a plurality of second light guide holes  43 . The second light guide holes  43  form the plurality of second light output areas  41 . The second light guide hole  43  constrains the light beam emitted by the corresponding second UV light source  22  to transmit inside the second light guide hole  43 , whereby the light is concentrated to illuminate the lower light receiving surface  122 , and whereby the lower light receiving surface  121  is exempted from being interfered with by neighboring light sources. 
     In one embodiment, the first substrate  32  and the second substrate  42  may include a delustering material, which can decrease the refraction while the light passes through the light guide hole  33  or the second light guide hole  43 . In one embodiment, the substrate  32  is made of a plastic material. In another embodiment, the substrate  32  or the second substrate  42  is made of a glass or metallic material coated with a delustering film. In one embodiment, the carrying device  10  is a transport mechanism (such as the conveyor  50  in  FIG. 1 ), which moves in an inching way to transport each mold cavity  11  to a position between one first UV light source  21  and one second UV light source  22 , whereby the mold  12  carried by each mold cavity  11  is arranged corresponding to the first UV light source  21  and the second UV light source  22 , and whereby the contact-lens polymer  13  inside the mold  12  is cured by the illumination of UV light. After cooling down, the mold  12  is split to obtain a contact lens. Via the first light guide device  30  and the second light guide device  40 , the present invention makes the light beams of the first UV light source  21  and the second UV light source  22  able to effectively illuminate the whole mold cavity  11 . Thereby, the upper light receiving surface  121  and the lower light receiving surface  122  are fully illuminated, and the contact-lens polymer  13  inside the mold  12  is uniformly cured. Thus, the present invention can shorten the curing time, promote the yield and decrease the fabrication cost. 
     In the abovementioned embodiments, the diameters of the first light guide hole  33  and the second light guide hole  43  are slightly greater than the light source and designed to be a cylindrical-shaped hole. However, the present invention does not limit the shape and size of the first light guide hole  33  and the second light guide hole  43  but allows the shape and size to be modified according to practical requirement. Refer to  FIG. 3 .  FIG. 3  is a sectional view schematically showing a UV curing apparatus  200  for a contact-lens polymerization process according to a second embodiment of the present invention. The second embodiment is different from the first embodiment in that the diameter of the first light guide hole  33  is gradually decreased from the position near the first UV light source  21  to the position far away from the first UV light source  21 . In other words, the first light guide hole  33  is a conical-shaped hole in the second embodiment. Similarly, the diameter of the second light guide hole  43  is designed to be gradually decreased from the position near the second UV light source  22  to the position far away from the second UV light source  22 . In other words, the second light guide hole  43  is a conical-shaped hole in the second embodiment. Therefore, the present invention can make light uniformly illuminate the mold  12  via decreasing the divergence angles of the light beams projecting from the first light guide hole  33  and the second light guide hole  43 . 
     Refer to  FIG. 4 .  FIG. 4  is a sectional view schematically showing a UV curing apparatus  300  for a contact-lens polymerization process according to a third embodiment of the present invention. The third embodiment is different from the first embodiment and the second embodiment in that the first light guide device  30  includes a plurality of light-focusing lenses  34 , which form the plurality of light output areas  31 . The light-focusing lenses  34  can make the light beams passing through them vertically project onto the upper halves of the mold cavities  11 , i.e. vertically project onto the upper light receiving surfaces  121  of the molds  12 . In one embodiment, the light-focusing lens  34  is a Fresnel lens. In the third embodiment, the light-focusing lenses  34  are used to modify the illumination paths of the curing light sources and improve the problem of light scattering, whereby the planar light receiving surfaces  121  of the molds  12  can be more uniformly illuminated. 
     Refer to  FIG. 5 .  FIG. 5  is a sectional view schematically showing a UV curing apparatus  400  for a contact-lens polymerization process according to a fourth embodiment of the present invention. The fourth embodiment is different from the third embodiment in that the diameter of the second light guide hole  43  is designed to be gradually decreased from the position near the second UV light source  22  to the position far away from the second UV light source  22 . In other words, the second light guide hole  43  is a conical-shaped hole. Thereby, the lower light receiving surfaces  122  of the molds  12  are illuminated more uniformly via decreasing the divergence angles of the light beams projecting from the second light guide hole  43 . 
     The embodiments described above are only to exemplify the present invention but not to limit the scope of the present invention. Any equivalent modification or variation according to the spirit or characteristics of the present invention is to be also included by the scope of the present invention.