MXPA97006914A - Demolde of ophthalmic lenses with laser deescudriñamie - Google Patents

Abstract

The present invention relates to an apparatus for separating the portions of at least one mold comprised of at least two mold portions including a first mold portion and a second mold portion containing ophthalmic lenses therebetween, said apparatus comprises: means for placing the mold portions containing both to the ophthalmic lenses, holding some or both mold portions in a work station, a source of intense electromagnetic radiation which is absorbed by the material of at least one of the mold portions to cause an increase in the temperature of said material, means for directing said radiation from the source to collide with the external surface either of one or both mold portions, said radiation direction means comprise of scrutiny to plot predetermined patterns on said surface to vary the amount of radiation energy for Different surface areas, and means for controlling the duration of said intense radiation shock on the mold portions sensitive to said plotting patterns to cause, during the radiation shock, a controlled increase in the temperature of surface areas of the mold portions that receive the shock of radiation from said

Description

DISMOLLING OF OPHTHALMIC LENSES WITH LEFT SCREENING BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a method and apparatus for the improved removal of ophthalmic lenses molded from the mold in which they are produced. In particular, this invention is suitable for molded ophthalmic lenses such as hydrogel contact lenses, although the method is also adaptable to the molding methods used in connection with other small high precision ophthalmic lenses, such as intraocular lenses. The phenomenal growth of the industry that is committed to the manufacture of the ever popular ophthalmic contact lenses, especially the aspects of the industry that pertains to the supply of contact lenses that are intended to be periodically replaced frequently by the user, has increased dramatically the need to mass produce immense quantities of such lenses that are of consistently high quality, while being inexpensive to produce them. Consequently, proportional to the industry's previous needs, this has required that the manufacturers of such lenses struggle to develop automated methods and apparatus that are particularly adaptable to high-speed automated production practices, and that work with consistency to degrees adequate accuracy or precision in a highly cost-effective manner and consequently economically viable. In accordance with currently developed technology which is related to the production of ophthalmic lenses, particularly such as soft contact lenses of the hydrogel type, a monomer or rnonomer mixture which is polymerizable in a plastic mold is normally used. In general, although not necessarily, the material for the ophthalmic contact lenses is selected from an appropriate hydrophilic material, preferably a monomer to form a so-called polymer based on HEMfl (hydroxyethyl ethacrylate), although other suitable polymerizable rnonomers can also be used for lenses, as discussed below.

DISCUSSION OF THE PREVIOUS TECHNIQUE Direct molding methods or methods that are typically used in accordance with the current state of the art to form soft ophthalmic hydrogel contact lenses can be easily found; for example, in the patent descriptions of E.U.fl. Nos. 5,080,839 by Larsen; 5,039,459 by Larsen et al .; 4,889,664 by Larsen et al .; and 4,495,313 by Larsen. As is clear in the patents of E.U.fl. As mentioned above, the procedures for forming soft ophthalmic con + act lenses can include the steps of dissolving a mixture of monomer and a nonaqueous solvent displaceable with water, and then placing the mixture of monomer and solvent in a mold by supplying a mold cavity. that is in the configuration of the hydrogel contact lens finally desired. Subsequently, the mixture of monomer and solvent is subjected to physical conditions which cause the monomer or monomers to polymerize, thereby producing a mixture of polymer and solvent in the form of the final hydrogel contact lens. After finishing the above procedure, the solvent is displaced with water to produce a hydrated lens whose final size and shape are similar to the configuration of the molded polymer and the original solvent article. The basic molds that are used to receive the polymerizable monomer-fed material to form the lenses are described, for example, in the U.S. Patent. Nos. 5,094,609 by Larsen; 4,640,489 by Larsen et al .; and 4,565,348 by Larsen. In general, for example, as described in the patent of E.U.fl. No. 4,640,489, the mold that is used consists of a two-piece mold having a front mold portion or female portion with a generally concave lens surface., and a back mold portion or male portion having a generally convex lens surface and mating to mate with the female mold portion, with both mold portions being preferably formed of a thermoplastic material, such as polystyrene. As described in the patent of E.U.fl. above, it is considered that the pol is + irene and the copolymers thereof are a preferred mold material, since they do not crystallize during the cooling of the fused alkali bath which is used to form the lenses and, consequently, exhibits little or no no shrinkage when subjected to the processing conditions that are required during the direct molding process, as discussed above. Alternately, appropriate molds may also be used which are made of polypropylene or polyethylene; in essence, this is described in specific detail in the description of the US patent. No. 4,121,896. During the completion of the molding process, the monomer and the monomer mixture are supplied in an amount in excess of the concavity of the concave female mold portion before coupling the female and male mold portions. During the assembly of the female and male mold portions, which together would define between them the lens formation cavity between the concave and convex mold portions of the mold, and which also provide a peri.etric edge of the lens, the excess of rnonornero or of the rnonomer mixture is expelled or leaves the mold cavity and comes to rest in a flange or between flanges that surround any of the coupled mold portions. After polymerization, this excess material which is derived from the onomer or the ring mixture produces an annular flange or ring of the HEMfl-based material which is used to produce each of the contact lenses to extend around the externally formed lens. to the mold cavity between the flange structure of the coupled female and male mold portions. In accordance with the patent disclosures of E.U.fl. aforementioned Nos. 5,039,459; 4,889,664; and 4,565,348, the requirement is established that the materials for the mold and the lens, as well as the chemical and physical procedures that are implemented during the molding sequence, are controlled in a manner whereby the coupled mold portions can be easily separated. without the need to apply undue force, which may sometimes be needed when the molded lens adheres to the lens mold, or in the event that the coupled mold portions exhibit a tendency to adhere to each other after polymerization of the lens. lens material. Taking into account the above, the procedures according to the prior art that are used to separate the mold portions and to remove the molded lens therefrom, essentially comprise a preheating stage, a heating step and a physical or mechanical leverage. and separation of the mold portions and then, a method for removing the lens. The preheating and / or heating step used in the above method of separating the mold and removing the lens contemplates applying heat to the back mold portion, usually the convex mold portion or male portion, generally by the application of an air stream heated, by means of convection. Since a differential expansion resulting from the polymer material of the heated mold relative to the colder polymer material of the lens produces a tendency to change one surface with respect to the other, the applied levering force breaks the adhesion between the polymerized lens and the contiguous polymer mold, and facilitates the separation of the mold portions. The longer the temperature gradient between the surfaces of the mold portions, the greater the shear force that it generates, and the easier to separate the mold portions. This effect is achieved to the maximum in the presence of a maximum thermal gradient. More recent techniques that have been developed, or are currently in the process of being developed to achieve a temperature gradient between the male (posterior) portion of the lens mold and the contact lens, include procedures involving the lens removal technology with laser beam, as described in the co-pending EUfl patent application. No. 08 / 431,552 (Flttorney Docket No. 8999Z, VTN-0075), which is assigned to the joint attorney of the present application; or by implementing the vapor shock to generate the necessary temperature gradient, as described in the present invention and in the co-pending patent application of E.U.fl. No. 08 / 258,265 (Flttorney Docket No. 9006, VTN-0082), which is also assigned to the joint attorney of the present application; and wherein the descriptions of the previously identified applications are incorporated herein by reference. At present, the method of lever-off of the coupled mold portions of the lens containing the polymerized contact lens in a molding cavity that is located therebetween is adapted to be achieved by the application of mechanical leverage. , whereby the lever or lever action can be implemented automatically from one side of the coupled mold portions of the lens. For example, the patent description of E.U.fl. No. 4,889,664, referred to above, discloses a test accessory that is used to measure the forces required to open or separate the coupled mold portions. The test attachment describes a fastening fixture for retaining the lower mold half of the lens, and a lever structure that can be positioned between the upper mold half portion and the lower mold half portion, and meshes with the first so as to allow the lever portion of the upper mold half portion of the lower mold half portion to be controlled at a controlled rate of separation from the mold. In general, said lever structure for levering out the mold portions of the lens consists of a plurality of leverage fingers which mesh under the flange structure encompassing the upper mold half portion, the latter of which defines generally the rear curve of the lens being molded, and the vertical lifting force imparted towards the upper mold half portion by the lever fingers engaged with it, is normally sufficient to disengage the coupling portions of the mold in order to to allow the separation thereof and allow access to the contents of the mold cavity, in effect, the molded ophthalmic contact lens. Since the leverage is generally effected from one side of the flange structure of the curved half portion of upper mold or back portion, and the opposite side is not supported, the rear mold half portion tends to pivot on the Curved portion of front mold or portion of bottom to crush the material at the edge of the lens contained therein. This is potentially a possible source of damage that is imparted to the contact lenses during the separation of the mold, making the lenses unusable and the lens manufacturing process not economically viable for mass production techniques. Another version of the mechanical separation by lever action of said half-mold coupling portions, and which facilitates this procedure to a reduced force application, while concurrently potentially preventing or at least appreciably reducing the degree of any possible adhesion between yes of the half-mold portions, with the mechanical leverage applied to the upper mold half portion, in addition to the application of the heating action to it, either through steam shock or with laser beam, contemplates imparting a movement to the squeezing finger with respect to the perimeter of the upper mold half so contacted, in order to apply a predetermined pattern of movement to the squeezing fingers engaging the flange of the upper mold half, while concurrently effecting a lifting action, as described in the co-pending EUfl patent application. No. 08 / 257,871 (Flttorney Docket No. 9008; VTN-84). This, in essence, causes the upper mold half portion to gradually move away from the lower mold half portion at a controlled variable speed and at an angular orientation specified therebetween, ensuring that the spacing between the half-mating portions The mold can be implemented in the most advantageous and convenient manner, while concurrently reducing or even completely inhibiting the risk of any potential damage that can be faced by the mold half portions and the molded lens when carrying out this particular demoulding process. of the lens.

A particular problem encountered is the aspect that the mold portions are often surrounded by a flange, and the monomer or monomer mixture is supplied in excess to the concave portion of the mold before coupling the molds. After the mold portions are placed together, defining the lens and forming an edge, the excess rnonorne or the rnonomer mixture is expelled from the mold cavity and lies in or between the flange of one of the mold portions or both After polymerization, this excess material forms an annular flange or ring around the formed lens. Reiterating the aspects of the previous method to separate the mold portions and remove the lens, this basically consists of preheating, heating, levering and removal. The hot air provides the heating, the mechanical lever the lever, and the removal is manual. Heating the mold by convection is not an efficient heat transfer technique, since from the moment a mold enters the heating apparatus until the back mold portion is completely removed, it takes the order of 1 minute. A general method for removing the lens is to apply heat to the back mold portion by means of a stream of heated air. The heating of the rear mold portion is done in two stages: a preheat stage and a heating / leverage stage. In the heating / squeezing step, the mold is held in place and the squeezing fingers are inserted under the rear mold portion. During the heating cycle, a force is applied to each subsequent mold portion. When the necessary temperature has been reached, the rear mold portion is separated and one end is lifted by the lever fingers. After the back mold portion has been separated from the front mold portion on at least one side, the mold then exits the heater. The back mold portion and the annular reheat are then completely removed. It is also possible to make hot or cold air collide on the outer surface of the front mold portion, to achieve other thermal gradients. The heated air is blown on the outside of the rear mold portion where heat is transferred to the upper surface of the lens. The heat is transported through the back mold, the molded lens and the front mold by thermal diffusion. Although the aforementioned method has some efficacy to facilitate removal of the lens between the mold portions, the temperature gradient reached from the heated back mold portion, through the lens to the front mold portion, is relatively small . The deficiencies of this procedure result from the way in which the heat is brought to the mold portion. The constant temperature air stream heats the outer surface of the rear mold portion more rapidly, while thermal conduction transfers heat to the lens surface. The only way to increase the thermal gradient is to transfer the heat faster, but this would cause the back mold portion to soften too much so that the lift lever fingers can engage. As noted above, this method has not been fully satisfactory because the induced thermal gradient is not sufficient to completely and repeatedly separate the mold portions. The aforementioned laser demolding method, as described, for example, in the US patent. No. 5,294,379, filed March 15, 1994 (flttorney Docket No. VTN-042), which is commonly assigned to the attorney of the present application, and the description of which is incorporated herein by reference, utilizes a source of electromagnetic radiation, preferably a carbon dioxide (CO2) laser, applied to at least one of the mold portions. The laser is on a scale of wavelengths between about 1 μrn and 20 μm and preferably at a wavelength of 10.6 μm. The exposure of the mold portion to the laser is between 0.4 seconds and 1 second, and it needs a laser of 373 Uatts for the heating of 8 molds. Since the differential expansion of the heated mold polymer with respect to the cooler lens polymer layers one surface with respect to the other, the shear force breaks the polymerized lens mold / polymer adhesion and aids in separation of the mold portions. The greater the temperature gradient between the surfaces of the mold portions, the greater the shear force and the mold portions are more easily separated. This effect is greater when a maximum thermal gradient is present. As time goes on, heat is lost through the conduction of the back mold portion to the lens polymer and the anterior mold portion, and then collectively to the surrounding medium. The back mold portion heated rapidly is thus separated so that very little energy is transferred to the polymer lens, avoiding the possibility of thermal lens decomposition. Lasers are typically the most intense sources available and, therefore, maximize the efficiency of the energy transfer from the source to the workpiece. "Intense" refers not to the total product of the source, but rather to the concentration of its energy. Other intense sources of electromagnetic energy capable of heating effectively and rapidly, such as rnicroondae generators, can be used. The characteristic shared by these sources, defined as intense, is that the area covered by the product at the distance of the workpiece is in the order of the area of the workpiece. Also, due to the absorbing nature of 1.4 Mold material at these frequencies, most of the laser energy that is absorbed within the various wavelengths is displaced to the material. From that point, heat is transferred only by conduction from the surface. For that reason, with the initial exposure to the laser beam, a huge thermal gradient is formed between the exposed outer surface and the surface of the mold portion in contact with the lens. In addition, non-uniform heating can also be caused by an inhomogeneous energy density through the laser beam. Although the previous demolding performed through the intermediate part of radiation energy, particularly such as a laser, is generally satisfactory, some problems have been encountered in that there is no non-uniform heating applied in the various mold portions or surface areas due to the differences in thickness and curvatures found by the laser.

BRIEF DESCRIPTION OF THE INVENTION In order to improve the above and to improve or even completely eliminate the problems encountered in the normal laser demolding apparatuses and methods, as described hereinabove, the present invention contemplates the use of a scrutineer arrangement, particularly the use of a X-Y scanner comprising mirrors driven by a galvanometer, which moves a small laser spot; for example, to the extension of 0.8 mm in diameter, which will cause the laser to draw spiral or grid patterns or other suitable models of predetermined duration in time on the surface areas of the mold and lens portions. The laser beam narrows or focuses to the diameter of 0.8 nm before striking the mirrors that are mounted to and driven by the galvanometers. Galvanometers, two of which are required; that is, one for each mirror, the mirrors then move to direct the beam in its predetermined pattern through the surface of the mold part; in essence, the base curve. Preferably, the mirrors are made of a metal, such as beryllium, which is capable of withstanding the large amount of energy typically provided by CO2 lasers - this will, in effect, vary the amount of energy transmitted to the different areas and is useful for reducing the energy in the places or portions of the surface areas in which the lens is thin or in that the absorption by the material of the lens and the mold parts, such as the thermoplastic involved, varies in its intensity by virtue of of acute or changing surface angles found by the laser spot. In this way, by providing controlled surface models on the mold portions by means of lasers due to the use of the screener, the temperature increase can be controlled to a precise degree in the distribution on the surface more than in previous times which will eliminate as a result Any information about lae called hot spots that could conceivably damage the lens during the. demolding procedure. In addition, another aspect that provides the advantageous use of the X-Y scanner of mirrors driven by a galvanometer in the scanning laser application that demolishes the components through the intermediate part of a laser scanning module, lies in that it makes possible the scrutinizing a multitude of lenses; for example, 8 lenses contained in the molds arranged on a single pallet, in a single workstation instead of having to employ movement devices to rotate the pallet from position to position to individually laser strip each lens. Although a CO2 laser can be used, producing radiation on the medium scale of infrared radiation at a wavelength of 10.6 μm, it is also possible to use a high power ultraviolet laser or a high intensity electromagnetic radiation emitter of any type in which the radiation produced from the mold material is absorbed sufficiently to cause an increase in the temperature of the mold material. Therefore, it is an object of the present invention to provide a novel laser demolding apparatus in lime using a scrubber facilitates selectively drawn eepiralee patterns, concentric circles, overlapping coils, circular patterns, grid patterns or any other suitable scrolling paths for vary the energy provided to the different lens mold surface areas. A more specific objective of the present invention lies in the production of an X-Y scanning system of mirrors driven by a galvanometer which causes a small laser spot to trace predetermined successive scanning patterns on the mold portions arranged on a stationary pallet or support. , which will controllably vary the amount of radiation energy provided to the various surface areas of the mold of each of the mold portions. Yet another objective of the present invention is to provide a method for providing the laser-controlled release of ophthalmic lenses in which the laser is controlled by means of a scanning system in order to trace the predetermined patterns to vary the amount of energy provided for different areas. Yet another object of the present invention is to provide an apparatus as described herein in which predetermined patterns can be traced by a laser scanner that incorporates galvanometer-driven mirrors that control the laser spot directed against the surfaces of the mold in order to of controlling the intensity of radiation and heating of the lens surfaces and the mold parts.

BRIEF DESCRIPTION OF THE DRAWINGS Reference may now be made to the following detailed description of a preferred embodiment of the invention, taken in connection with the accompanying drawings; in which: Figure 1 illustrates a graphic representation of the transmission of polyetherene radiation as a function of a wave number on the infrared radiation scale; Figure 2 illustrates a cross-sectional view of a molded ophthalmic lens contained between the two sections of the mold; Figure 3 illustrates, in a generally schematic manner, an optical succession and focusing mirrors driven by a galvanometer of the laser scanning system according to the present invention; Figure 4 illustrates a generally perspective schematic view of an accessory apparatus for separating mold portions according to the invention; and Figure 5 illustrates a vertical side view of the accessory apparatus of Figure 4, shown in the position after the mold portions have been separated.

DETAILED DESCRIPTION OF A PREFERRED MODALITY Figure 1 shows the absorption of radiation by a polystyrene plate of 1 mm in the infrared spectrum. For the CO2 laser described above, the wavelength of 10.6 μrn of the radiation produced has a corresponding (reciprocal) wave number of 943.3 crn-i. Hitherto, as also described in the above patent application, a laser demolding system employed special optics in order to generate a laser-integrated intensity in the target, in essence, in the mold portion. Generally, the mold portions were supported on a pallet that was continuously moved past a laser spot fixedly fixed to a work station, whereby in order to use the laser system to heat the 8 lenses or mold portions. of objective that are supported on a pallet, this needed the use of a relatively large and consequently expensive laser; for example, a laser needed 373 Uatts in order to heat 8 mold portions or ophthalmic lenses. In contrast to the above, the scanning system of the inventive laser focuses a basic beam of laser to a final diameter size of the spot, before the beam hits a pair of mirrors that are mounted on the galvanometers. The mirrors are adapted to move, respectively, in the directions X and Y in response to the drive by the galvanometers, the latter being controlled by the microprocessor in order to direct the laser beam in a predetermined pattern or scan through the surface successively of each mold portion. Referring to Figure 2, a pair of mold portions coupled with a lens therebetween are shown in cross section. The mold portions are constituted by an anterior portion 20 and a posterior portion 22, preferably made of polystyrene material. Between these two mold portions eet the lens 24 and an excess polymer ring 26 out of the mold cavity forming the lens. The difference in temperature between identical locations on the anterior and posterior mold portions can be up to 35 ° C, greatly facilitating the removal of the posterior mold portion from the anterior mold portion and the lens. The methods according to the prior art for heating the back mold portion using a heated fluid resulted in a temperature difference of about 3 ° to 5 ° C and required in the order of a medium to one and a half minutes to achieve the maximum difference in temperature. If a lens / mold combination was overexposed to the laser energy, separation of the mold portions and lens removal would again be difficult. It would result in mold damage such as oxidation and melting (softening), and the loss of mold stiffness would defeat the separation of the mold. In addition, overexposure thermally degrades the lens. Referring to Figure 3 of the drawings, the inventive laser scanning system 60 is described. A laser generator 62 directs a laser beam LB through a focusing lens 64 or optical instrument that focuses the beam L to a size up to reach a final diameter; preferably such as 0.8 m. With the beam focused on the output side of the focusing lens or optical instrument 64, the beam impinges on a first high energy mirror 66, preferably made of metal, such as beryllium, and from which it is then directed again, for example, towards the rear curve 22 of a mold by a second high energy mirror 68 which is also made of metal, such as beryllium, in order to be able to form a laser scanning pattern and to redirect the beam from a first mold portion to a sub-sequential portion of mold placed on a pallet or support (not shown), each of the mirrors 66, 68 is adapted to be displaced, respectively, in a suitable X and Y direction by means of a pair of galvanometers actuators 70, 72 to each of which one of the respective mirrors is fixed and by means of which movement is imparted to the galvanometers 70, 72 by means of a suitable microprocessor 74 programmed by computer so controlled default In this way, a suitable laser scanner model is provided for each mold portion; for example, in a circular pattern, grid pattern, overlapping coils, circular trackers or any other suitable pattern adapted to impart a desired amount of heat to the various surface areas of the mold portion to pass to a subsequent or successive mold portion. which is located on the stationary paddle in the particular laser scanning work station. The previous concept of using a laser scanner system 60 incorporates mirrors driven by galvanometer 66, 68, provides a considerable reduction of energy; for example, only 203 Watts of the laser are required to supply the required amount of energy in 1.2 seconds. In this way, by moving the laser spot very quickly, the mold material is heated instead of being cut, and the galvanometer can accurately move the LB beam at speeds of more than 25.4 meters per second. In order to improve the temperature distribution produced by the laser beam on the surface areas of the mold portion and thus avoid the formation of hot spots or inadequate temperature differences that would adversely affect the quality of the ophthalmic lenses, the laser scanning system X-Y 60 (schematically illustrated) which incorporates the mirrors operated by galvanometer 66, 68, which forms a small movable laser spot, for example of the size of 0.8 m. The scrutineer makes it possible for the laser spot to trace spiral patterns, grid patterns, circular scrolls, overlapping coils or any other suitable scanning paths on the surface areas of each mold portion 22 which varies the amount of energy imparted to the different areas and it is useful to reduce the energy where the lens is thin or where the absorption of the plastic material of the lens or the mold portion can vary widely due to the acute surface angles that are incised by the laser beam. This, in essence, makes possible the controlled formation of scouting patterns, thus providing the required amounts of heating of the various surface portions in order to provide the appropriate temperature differences in order to obtain the maximum separation effect between the halves or mold components while maintaining the integrity and quality of ophthalmic lens. The lens / mold combination can be placed in a conventional manner by holding one or both mold portions (with the lens between them) in an accessory shown in Figures 4 and 5. The main requirement of this accessory, beyond the mechanical stability , ee not interfere with the beam of electromagnetic radiation. This is the reason why it is preferred to hold the lens / mold combination only by the first mold portion and irradiate the second mold portion. Shown in Figures 4 and 5 is a lens / mold combination identified in Figure 2 with element 20, 22 and 24, and holding the accessory 80. This lens / mold combination is constituted of the anterior mold portion and the posterior mold portion with the lens positioned between them, as identified in Figure 2. For the In the described system, only the rear mold portion 22 is heated by exposure to radiation. The back mold portion is thinner and allows quick, non-thinning heating of the polyetherene sufficient to form a large thermal gradient. The thicker anterior mold portion containing a larger amount of polystyrene would not heat up as quickly and would not produce the same thermal gradient without overheating problems encountered. For this reason, referring to Figure 4, the squeeze 82 and the leg 84 are placed between the front mold portion 20 and the back mold portion 22. As the lens / mold combination is held, the laser energy is directed in a scanning pattern through the channel 86 in the assembly 80 and over the rear mold portion 22. It would be possible to heat both mold portions, but it would not produce any advantage over the heating of only the rear mold portion 22. It was found that the preferred method for removing the back mold portion of the front mold portion after heating the back mold portion with the laser was to apply a relative tension force between the mold portions. Referring to Figure 5, the thin metal legs 84 that are located below the flange of the back mold portion are turned flat on both sides. The upper part of the assembly 80 is imparted with a vertical lifting force so that after exposure of the mold portion to the laser, the legs 84 leverage the rear mold portion 22 toward the rim. It was determined that it is better that the mechanical aid described above be given less than 0.3 seconds after exposure to radiation. Although no adverse effects would be contemplated if the time between exposure and mechanical removal were less, in practical terms, the term between exposure and mold separation would be between about 0.2 and about 1.5 seconds. Beyond a delay of 1.5 seconds, the difficulties in mold separation and lens removal would be the same as those arising from overexposure, as previously described. One consideration and significant quality advantage of the present invention is the consistent retention of the lenses in the front mold portion when the back mold portion is heated with the laser and removed in accordance with the prior art. With reference to the foregoing, the use of a X-Y 60 scanner incorporating the galvanometer-operated mirrors 66, 68 facilitates the scanning and application of controlled radiation energy to a plurality of ophthalmic lenses, for example eight lenses that are contained in molds on a single pallet in a single workstation without having to move the pallet, and simply controlling the movements of the laser point due to the X-Y displacement of the scanning laser by means of the mirrors, and imparting a predetermined scanning pattern each of the surfaces of the lenses and respective mold portions containing the lenses. As might be expected, an increase in lens defects correlates with the occurrence of high energy I areas or hot spots in the beam profile. This is expected because overheating in one area weakens the lenses, making them susceptible to tearing, splintering, or being torn off from the surface of the front mold portion. With optimal exposure time and laser scanning, and the appropriate demoulding mechanism, such as wedge-shaped leverage legs, the mold portions can be separated and the lenses can be removed from the mold in the course of about 5 seconds. The foregoing is by way of example for the preferred polyethylene mold system, as can be readily appreciated by the skilled person, the radiation wavelengths, power levels, and exposure times should be adjusted approximately in accordance with the foregoing considerations for achieve the optimum characteristics for other lens / mold material systems. The anterior scanning laser system 60, although described in connection with the demolding of a plurality of mold portions or ophthalmic lens molds arranged on a stationary pallet, is also capable of being programmed by means of the microprocessor 74 by dragging a moving pallet that go through the work station. In addition, the field strength over the scanning area is programmable and limited only by the size of the point and the number of scrutinies, the last of which, as mentioned above, can provide scanning trajectories or concentric circles, spirals of overlap, circular patterns of line, among many other potential trajectories of scrutiny. Although it has been shown and described what are considered the preferred embodiments of the invention, it will be understood, of course, that modifications and changes in shape or detail can be made easily without departing from the spirit of the invention. Therefore, it is intended that the invention not be limited to the exact form and detail shown and described herein, and to nothing less than the total of the invention described herein, as claimed below.

Claims (29)

NOVELTY OF THE INVENTION CLAIMS

1. An apparatus for separating portions of at least one mold comprised of at least two mold portions including a first mold portion and a second mold portion containing ophthalmic lenses therebetween, said apparatus comprising: means for placing the mold portions containing both to the ophthalmic lenses, holding some or both mold portions in a work station; a source of intense electromagnetic radiation which is absorbed by the material of at least one of the mold portions to cause an increase in the temperature of said material; means for directing said radiation from the source to collide with the external surface of either one or both mold portions, said radiation direction means comprise scanning means for tracing predetermined patterns on said surface to vary the amount of energy of the radiation. radiation for different surface areas; and means for controlling the duration of said intense radiation shock on the mold portions sensitive to said plotting patterns to cause, during the radiation shock, a controlled increase in the surface area temperature of the mold portions which they receive the shock of the radiation of said source.

2. The apparatus according to claim 1, further characterized in that said scanning means comprises a plurality of mobile mirrors driven by galvanometer in XY direction, said radiation direction means include optical lens means interposed between said source of radiation. electromagnetic radiation and said mirrors to focus the radiation in a beam reflected by the mirrors towards the mold portions to facilitate the formation of a radiation pattern by reducing the energy in the thin areas of the lens or where the absorption of energy by the mold or mold material varies in response to the presence of a sharp surface angle.

3. The apparatus according to claim 2, further characterized in that said plurality of mirrors comprises two mirrors; a first galvanometer connected in operation to a first mirror to drive said mirror in a first orientation; a second galvanometer connected in operation to a second mirror to drive said mirror in a second orientation to provide a scanning pattern X-Y.

4. The apparatus according to claim 3, further characterized in that the icroprocessor means are connected to said galvanometers to impart predetermined controlled activation towards the mirrors.

5. The apparatus according to claim 4, further characterized in that said microprocessor means is controlled by a computer.

6. The apparatus according to claim 2, further characterized in that said objects are made of metal.

7. The apparatus according to claim 6, further characterized in that said metal comprises high-energy beryllium resistant.

8. The apparatus according to claim 1, further characterized in that said scanning means facilitate the sequential scanning of a plurality of said lenses and molds located in a single pallet at said work station.

9. The apparatus according to claim 1, further characterized in that the source of intense electromagnetic radiation is a laser.

10. The apparatus according to claim 1, characterized in that the radiation has a wavelength between about 1 μrn and about 20 μrn.

11. The apparatus in accordance with the claim 9, further characterized in that said laser facilitates the use of a small laser point to trace said scanning patterns.

12. The apparatus according to claim 11, further characterized in that said pattern comprises a spiral pattern drawn by said laser point.

13. - The apparatus according to claim 11, further characterized in that said pattern comprises a grid pattern drawn by said laser point.

14. The apparatus according to claim 11, further characterized in that said laser point has a diameter of about 0.8 mm.

15. The apparatus according to claim 1, further characterized in that said means for positioning support said first mold portion, thereby holding the second portion of mold and the lenses attached thereto, and the source of radiation is directed to colliding with the outer surface of said second mold portion.

16. A method for separating the portions of at least one mold comprised of at least one first mold portion and a second mold portion, both of which contain ophthalmic lenses, said method comprising: holding at least one of said mold portions in an assembly, thereby supporting the mold portions containing the ophthalmic lenses therebetween; directing a source of intense electromagnetic radiation to which the material of at least one of the mold portions is sufficiently absorbent to cause an increase in the temperature of said material; colliding the outer surface of one or both mold portions with said electromagnetic radiation in a predetermined scanning pattern that extends over different surface portions of the mold portions; controlling the duration of said radiation shock while scrutinizing said surface patterns with the radiation to cause, while the shock of the radiation lasts, an increase in the surface temperature of the mold portion colliding with the intense electromagnetic radiation, but it essentially does not raise the temperature of ophthalmic lenses; and separating the mold portions after they have been shocked.

17. The method according to claim 16, further characterized in that said scanning pattern facilitates the formation of a radiation pattern that reduces energy in thin areas of the lens or where the absorption of energy by the mold or material of mold varies in response to the presence of a sharp surface angle.

18. The method according to claim 16, further characterized in that the sequential scanning of a plurality of said lenses and molds while they are located in a single pallet is facilitated.

19. The method according to claim 16, further characterized in that said electromagnetic radiation comprises laser energy.

20. The method according to claim 19, further characterized in that said laser energy has a wavelength of between about 1 μm and 20 μm.

21. The method according to claim 19, further characterized in that said laser energy comprises n focused laser point.

22. - The method according to claim 20, further characterized in that said laser point has a diameter of about 0.8 mm.

23. The method according to claim 20, further characterized in that said laser point traces a spiral scrolling pattern on said surface. 24.- The method of compliance with the claim 20, further characterized in that said laser point draws a squared squaring pattern on said surface. 25.- The method of compliance with the claim 21, further characterized in that said laser point is formed by a laser beam directed by moving mirrors driven by a galvanometer. 26.- The method according to claim 25, further characterized in that said mirrors driven by galvanometer are controlled by a microprocessor so as to implement a scrolling pattern movement XY. 27.- The method according to the claim 16, further characterized in that said first mold portion is maintained in said assembly, the electromagnetic radiation is directed to the second mold portion which is then struck by the electromagnetic radiation, and said separation is carried out by applying a frictional force between the second mold portion and the first mold portion. 28. The method according to claim 16, further characterized in that the first mold portion maintained in said assembly is the one that forms the front surface of the ophthalmic lenses, and the second portion of the mold shocked by the electromagnetic radiation is the which forms the posterior surface of ophthalmic lenses. 29. The method according to claim 16, further characterized in that said first mold portion is maintained in the assembly, said electromagnetic radiation is directed towards the second mold portion which is then struck by the electromagnetic radiation, and said separation is levering out of the second mold portion of the first mold portion and the lenses.