MXPA00001710A - Lens block and method of processing lenses - Google Patents

Abstract

A two-piece lens block (10) allows for the rotation of an edged lens blank (5) in order to align the cylinder of the lens blank (5) correctly. The lens block (10) includes a substantially cylindrical base (12) having a first surface (13) facing the lens blank (5) and an opposed second surface (15) with a plurality of driving recesses (14) extending into the base (12) from the second surface (15). A rotatable ring member (22) surrounds the base (12) and includes a mounting surface (24) generally adjacent to the lens blank (5). An edged lens-shaped cavity (26) is provided in the ring member (22) and provides for nearly full surface contact of an attachment alloy (17) with a front surface of the lens blank (5) to alleviated distortion. The two-piece lens block (10) allows edged lens blanks (5) to be surfaced to finished lenses.

Description

LENS BLOCK AND LENS PROCESSING METHOD BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to the processing of ophthalmic lenses and, more particularly, to lens blocks for the assembly of blanks of rimmed ophthalmic lenses.

Background of the Invention The glasses normally use lenses that have convex outer surfaces and concave interior surfaces. The two surfaces of each lens have different curvatures to obtain the optical refraction for the lens. For many lenses, the inner surface has the shape of a section of a bull. The direction along which the longest radius is generated is referred to as the cylindrical axis of the lens. These lenses are produced from a circular blank of glass or plastic lens that is subjected to multiple cutting and polishing steps on the surfaces. A lens holding plate, or lens block, adheres to the convex outer surface of the blank, which is otherwise known as blocking by techniques known in the art, to prepare the lens for surface treatment . See, for example, Figure 1 of U.S. Patent No. 5,520,568 and the description associated with that figure (in particular, columns 1-3), which are hereby incorporated by reference in their entirety.

The adhesion process of the convex outer surface of the lens blank to the lens block generally involves placing a tape, such as described in US Patent No. 4,287,013, on said outer surface, example the finished face of a semi-finished lens blank. The lens / tape subset is fixed to the block using a low melting temperature alloy. For example, a typical alloy having a melting point of about 117 ° F (47.2 ° C) and comprising 45% bismuth, 23% lead, 8% tin, 5% cadmium and % of Indian This alloy is injected in liquid form between the block and the tape and is adapted to the convex face of the blank of the lens. Currently, it is common to keep the blank of the lens mounted on the lens block throughout the entire surface treatment process to prevent reassembly of the lens blank on the lens block. The prior lens configuration techniques would remove and reassemble the blank from the lens on the lens block in various stages of surface processing. A major problem in refixing the lens blank to the lens block is the proper alignment of the optical center of the lens blank with the center point and cylinder axis of the lens block. See, for example, the lens blocks shown in U.S. Patent Nos. 2,352,616; 2,545,447; 3,015,196; 3,049,766; 3,192,676; and 4,149,344. After surface treatment of the lens block, the lens / tape subassembly is removed from the lens block by methods known in the art and the protective tape is usually removed by manually peeling it off the surface. After this, the peripheral edge of the circular blank is cut according to the final configuration of the mount or the lens, which is also known as bordering. In this step, the lens is fixed to a skirting block by fastening mechanisms known in the art, for example, in reissued US Patent No. 31,897, and the peripheral edge is processed to the desired configuration for the frame. selected. The use of a low melting temperature alloy to fix the sub-assembly of the blank of the lens / protective tape to the lens block suffers from certain drawbacks. For example, the hot alloy may damage the lens, for example, cracking a glass lens or warping a plastic lens. Thermal patterns can also be created on the convex outer surface of a plastic lens, that if they are not removed, they are seen by the user of the lens as distortion patterns. Generally, the adhesive or low melting temperature fixing alloy used to fix the lens block to the blank of the lens is carefully selected to minimize the above drawbacks. Some prior art lens blocks have caused irregular heating of a plastic lens blank, thereby leading to the generation of thermal patterns in the lens. When the thermal patterns are close to the edge, they can be removed from the circular blanks of the lens in the subsequent bordering operation. However, when the marking extends far into the center of the circular blank of the lens, the thermal patterns can not be removed during the bordering operation. Laminated lenses including at least two layers of glass or plastic to form the lens have recently been described. The probability of having the alteration problem described above will increase in the case of a laminated lens, particularly where the convex section of the lens adjacent to the lens block is thin. In addition, there is a tendency for the center of the laminated lens to heat up more than the edges by the fixing alloy. Recently, electro-optical lenses, such as electrochromic lenses, have been described. These lenses can be a set of laminated lenses that include an electrically activated section of one or more electrically activated layers between the outer layers of the lens. Each electrically activated layer is placed between two electrically conductive layers, for example, electroconductive metal oxide films. In the construction of the electro-optical lens, the conductive layers are insulated from each other to prevent a short circuit, and each conductive layer is provided with a separate conductor or contact point for connection to the electrical control circuit. These conductors or contact points can be easily fixed to the conductive layers after the lens has been edged to its final configuration for the selected frame. Alternatively, direct contact with a busbar (that is, without conductors) is possible. In the case of an electrochromic laminated lens, the surface treatment of the lens is typically carried out after the lens has been mounted and the conductors or contact points are fixed. Conventional lens blocks used with conventional lens blanks can not be used with an edged surface untreated electrochromic laminated lens, because the support area having the highest thermal gradient is generally within the viewing area. It is an object of the present invention to provide an efficient method for surface treatment of rimmed lens blanks by providing an improved lens block, wherein a rimmed lens blank can be freely and easily fixed thereto in a suitable aligned position. A further object of the present invention is to provide a lens block which would provide a sufficiently large contact area between a fixing material (eg, a metal alloy, wax or thermoplastic organic material having a suitable melting point) and the front surface of the blank of the rimmed lens to avoid patterns of thermal alteration. Still another object of the present invention is to provide a lens block that is easy and inexpensive to manufacture and use.

COMPENDIUM OF THE INVENTION The above objects are achieved by a two-piece lens block according to the present invention. The lens block includes a substantially cylindrical base and a ring element surrounding the base. The base has a first surface generally directed towards a blank of the rimmed lens. The ring element includes a mounting surface generally adjacent to the blanked part of the rimmed lens and a cavity configured in the form of a lens surrounded by the mounting surface. The cavity configured in the form of a lens is generally adjacent to the blank of the rimmed lens and provides substantially complete surface contact between a fixing material having a suitable melting temperature and the blank of the rimmed lens to limit or prevent distortion in the rough part of the rimmed lens. The fixing material may be an alloy of metal, wax or thermoplastic organic material. The ring element is rotatable with respect to the base before the attachment of the lens blank bordered to the lens block to allow proper orientation of the blank of the rimmed lens. The base includes a second surface opposite the first surface, and the base may include a plurality of drive recesses that extend into the base from the second surface. The base may be provided with a fixing supply hole extending from the second surface to its first surface. The supply hole is adapted to allow a fastening material to be injected therethrough to secure the lens blank to the lens block. A portion of the mounting surface of the ring element and a portion of the first surface of the base can be concave, generally adapting to the configuration of the lens blank. The ring element may additionally include a suitable number of fastening pins extending from its mounting surface and a plurality of notches extending to a peripheral edge of the ring element. The ring element may additionally include an annular wall opposite the mounting surface substantially surrounding the base and an annular stop abutting against the first surface of the base. A method of processing a lens blank according to the present invention includes mounting a lens blanket bordered on the lens block of the present invention in suitable alignment followed by the surface treatment of the bordered blank. generate the appropriate optical qualities for the finished lens. The mounting of the blanked part of the rimmed lens includes placing the blanked part of the lens bordered on the ring element adjacent the cavity configured in the form of a lens, aligning the ring element and the blank of the rimmed lens with respect to the base, and fix the lens blank, the ring element and the base together with suitable fixing material. Once the fixing material has been cooled until solidified, the ring can optionally be removed leaving a base and lens block attached. These and other objects of the present invention will be elucidated in the description of the preferred embodiments, which are described in connection with the appended figures, where like reference numerals represent the same elements generally.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a top plan view of a lens block according to the present invention. Figure 2 is a sectional view of the lens block shown in Figure 1. Figure 3 is a side view of the lens block shown in Figure 1. Figure 4 is a bottom plan view of the lens block shown in FIG. Figure 1. Figure 5 is a top plan view of the lens block shown in Figure 1 with a rimmed lens blank attached thereto. Figure 6 is a sectional view of the lens block shown in Figure 5; and Figure 7 is a schematic illustration of the block of the lens processing method according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS A lens block 10 according to the present invention is shown in Figures 1-6. The lens block 10 is intended for the assembly of a rimmed lens blank 5, shown in FIGS. 5 and 6 in imaginary lines, and includes a two-piece assembly that allows the rotation of the blanked part of the rimmed lens. 5 to correctly position the cylinder of the blank of the lens 5. The blank of the rimmed lens 5 can be an electro-optical lens, for example, a set of electrochromic laminated lenses, with the conductors fixed. This assembly may comprise a laminate of a blank of the convex rimmed lens, an electrochromic layer, an ion conducting layer, a complementary electrochromic layer, a second electroconductive layer, and a concave rimmed lens blank. This set of lenses may comprise a semi-finished lens blank, for example, it may be a single or semi-focal lens or other optical element. The lens block 10 can be formed of aluminum, however, other suitable materials can be used to build the lens block 10.

The lens block 10 includes a substantially cylindrical base 12 with a first generally concave surface 13 that faces generally towards the blank of the lens 5. The base 12 includes three actuation recesses 14 extending therethrough from one. second surface 15 opposite the first concave surface 13 and extending to the first concave surface 13. As shown in Figures 1 and 4, the operating recesses 14 extend along a diametral line through the base 12. The drive recesses 14 can receive drive projections 9 inside, as shown in Figure 6 for fastening to spindles or rotary drives of lens cutting and grinding machines, as is known in the art. The base 12 further includes the supply hole 16 extending therethrough. The supply hole 16 is adapted to allow a fastening material 17, shown in Figure 6, to be injected therethrough to fix the block of the lens 10 to the blank of the lens 5. Suitable fastening materials they have a melting temperature of about 120 ° F, such as the lead-indium alloy described above. Other suitable fixing materials include wax or thermoplastic organic material. The base 12 further includes a pair of reference holes 18 extending in the base 12 from the second surface. As shown in Figures 1 and 2, the reference holes 18 do not extend completely through the base 12 and end shortly before the first surface 13. A ring element 22 surrounds the base 12 and forms the second part of the base. Two-piece lens block. The ring element 22 has a concave mounting surface 24 which is generally adjacent to the blank of the rimmed lens 5. The mounting surface 24 of the ring element 22 surrounds a cavity configured in the form of a lens 26 formed in the mounting element. ring 22. The cavity configured in the form of lens 26 is intended to be slightly smaller than the blank of the rimmed lens 5 and is configured substantially similar thereto. The mounting surface 24 of the ring element 22 further includes a pair of diametrically opposed notches 28, each extending from the cavity 26 to a peripheral edge 27 of the ring element 22. The mounting surface 24 can additionally have two pairs of locating pins 30 diametrically opposite, extending from the mounting surface 24. Each locating pin 30 is mounted in a pin hole extending in the ring element 22. The ring element 22 includes a integral annular wall 32 which is opposite the mounting surface 24 and which surrounds the base 12. An annular stop 34 of the ring element 22 is adjacent to the cavity 26 and makes it abuts against a substantially flatter outer portion of the first surface 13 of the base 12. The annular stop 34 surrounds an opening 36 communicating with the cavity 26. Another embodiment is conceived without the annular stop 34, which allows the removal of the portion of the ring after the fixing material is injected and cooled to form a solid support in the configuration of the lens. In operation, which is schematically shown in Figure 7, the blank of the rimmed lens 5 is placed on the ring member 2 within locating pins 30 adjacent to the cavity 26. The block of the two-piece lens 10 of the present invention allows the rotation of the ring element 22 and the blank of the lens 5 with respect to the base 12 to separately align the blank of the rimmed lens 5 before the injection of the fixing material 17. The blank of the lens 5 must be aligned with respect to the base 12, because it is already cut according to the configuration, that is, bordered, and the cylinder to be cut in the blank of the lens 5 must be properly aligned on the lens final. Alignment is not a concern in the prior art using circular lens blanks, since during surface treatment these have not yet been edged. The alignment of the blank of the lens and the lens block is a concern, where, as in the present invention, the blank of the lens 5 is edged before the surface treatment. After proper alignment, the fastening material 17 can be injected into the cavity 26 through the supply hole 16 and through the opening 36. When injected, the fastening material 17 is essentially a liquid as shown in FIG. Figure 6. The notches 28 will accept any discharge such as a gas or excess setting material 17, as necessary. The fastening material 17 is rapidly modified to fix the blank of the lens 5, the base 12 and optionally the element of the ring 22 together within an integral unit. In an alternative embodiment, the ring element 22 can be removed after fixing. As described above, the annular stop 34 is not provided in the embodiment, where the ring element 22 must be removed after fixing. The cavity configured in the form of a lens 26 provides the almost complete contact of the fastening material 17 with the front surface of the blank of the rimmed lens 5 which must be heated substantially equal, thus relieving the probability of thermal distortion of the blank. rimmed lens 5. The distortion of the blank of the rimmed lens 5 should be avoided because no additional rim of the lens is available. The concave mounting surface 24 is substantially adapted to the blank configuration of the lens 5. The concave inner portion of the first surface 13 conforms to the configuration of the blank of the lens 5 and provides a substantially uniform thickness to the fixing material 17 in the cavity 26, which helps to maintain uniform heating of the blank of the lens 5. In the embodiments shown in figures 2 and 5, the flat outer portion of the first surface 13 which is supported against the annular stop 34 provides a junction against the fastening material 17. A relatively narrow fit between the outer surface of the base 12 and the annular wall 32 and between the drive projections 9 and the recesses 14 also provides union joints against the fastening material 17. After fastening of the blank part of the suitably bordered lens 6 aligned with the block of the lens 10, the blank of the The rimmed lens 5 will be surface treated according to the proper curvature in a conventional manner using techniques and machinery, such as a Coburn Model 108 generator, known in the art. As shown in Figure 4, the dimensions and configurations of the lower part of the lens block 10 are designed to conform to the standard surface treatment machinery of the lens. After the proper curvature has been formed on the concave side of the blank of the rimmed lens 5, the lens is finished, since it has been previously edged. The finished lens can be easily removed from the lens block 10 by heating the combined assembly beyond the melting temperature of the fixing material 17, which is generally carried out in a liquid bath. Other methods may be used for removal of the finished lens, such as by mechanical shock. This construction allows easy and proper locking of a blank of the rimmed lens 5 and allows essentially distortion-free processing of the rimmed lens blank 5. This process and apparatus will have particular application for electro-optical lenses. With this process, the blanks of the rimmed lenses 5, which require specific prescriptions that must be generated here, can be produced using the lens block 10 of the present invention. The cavity 26 is specific to a lens or a mount configuration. As a consequence, separate lens blocks 10 will be required for separate lens configurations. The illustrated embodiments are intended to be representative of the present invention and not limiting thereof. It will be obvious to those skilled in the art that various modifications to the present invention can be made without departing from the spirit and scope thereof. As a consequence, the scope of the present invention is intended to be defined by the appended claims.

Claims (20)

Claims

1. A method for processing rimmed lenses, comprising the steps of: placing a blank of the rimmed lens on a ring element adjacent a cavity configured in the form of the lens formed on said ring element, wherein said ring element surrounds the base; rotating said blank portion of the rimmed lens and said ring element with respect to said base to align said ring element and said base; fixing said blank part of the rimmed lens and said base, and superficially treating said blank of the rimmed lens to form a finished lens.

2. The method of claim 1, wherein said fixation includes the steps of injecting a fixing material through said base into said cavity configured in the form of a lens.

3. The method of claim 1, wherein said blank of the rimmed lens is an electro-optical lens and further includes the step of removing said ring after said fixing of said lens block and before said surface treatment of said blank. the rimmed lens.

4. A lens block for mounting a blank of the lens, said lens block comprising: a substantially cylindrical base, having a first surface directed towards the blank; and a ring element surrounding said base, said ring element having a mounting surface generally adjacent to the blank of the lens and a cavity configured in the form of a lens surrounded by said mounting surface, said cavity being configured in the form of lens generally adjacent the lens blank, wherein said ring element is rotatable with respect to said base prior to fixing said base to the blank of the lens.

5. The lens block of claim 4, wherein said base includes a second surface opposite said first surface and a plurality of actuating recesses extending in said base from said second surface.

6. The lens block of claim 5, wherein said base includes a hole extending from said second surface to said first surface, said hole being adapted to allow a fixing material to be injected therethrough, to fix the part. gross of the lens to said base.

7. The lens block of claim 5, wherein three of said actuation recesses are provided in said base and aligned along a diametrical line extending through said second surface.

8. The lens block of claim 7, wherein said lens block includes a hole extending from said second surface to said first surface, said hole being adapted to allow a fixing material to be injected therethrough to fix the gross part of the lens to said base.

9. The lens block of claim 8, wherein said mounting surface includes at least one notch extending to a peripheral edge of said ring element.

10. The lens block of claim 9, wherein said ring element includes locating pins extending from said mounting surface.

11. The lens block of claim 10, wherein said ring element includes an annular wall opposite said mounting surface, said annular wall surrounding said base.

12. The lens block of claim 11, wherein said ring element includes an annular stop adjacent said said lens-shaped cavity, said annular stop abutting against said first surface.

13. The lens block of claim 4, wherein said mounting surface is substantially concave.

14. The lens block of claim 4, wherein said ring element includes a plurality of locating pins extending from said mounting surface.

15. The lens block of claim 4, wherein said mounting surface includes at least one groove in the interior and extending to a peripheral edge of said ring element.

16. The lens block of claim 4, wherein said ring element includes an annular wall opposite said mounting surface, wherein said annular wall surrounds said base.

17. The lens block of claim 4, wherein said ring element includes an annular stop abutting against said first surface.

18. A lens block for mounting a blank of the lens, said lens block comprising: a substantially cylindrical base having a first surface directed toward the blank of the lens and a second opposing surface from said first surface, a plurality of drive recesses extending in said base from said second surface; and a ring element surrounding said base, said ring element having a mounting surface generally adjacent to the blank of the lens, wherein said ring element is rotatable with respect to said base element prior to fixing said base to the blank of the lens.

19. The lens block of claim 18, wherein said base includes a hole extending from said second surface to said first surface, said hole being adapted to allow a fixing material to be injected therethrough, to fix the part gross of the lens to said base.

20. The lens block of claim 18, wherein said ring element and said base define a cavity configured in the shape of the lens that is configured substantially the same as the blank of the lens and dimensionally smaller than said lens blank .