Blocking apparatus for lens manufacturing including automatic wax delivery system

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RELATED APPLICATIONS

This application is related to co-pending patent applications titled "An Apparatus for Precision Alignment During Blocking Process of Lens Manufacturing," U.S. Ser. No. 10/676,124 filed Oct. 2, 2003, "An Apparatus for Pressure Based Blocking Process for Lens Manufacturing," U.S. Ser. No. 10/676,126 filed Oct. 2, 2003, and "Blocking Apparatus Providing an Adjustable Offset for Precision Alignment," U.S. Ser. No. 10/676,127 filed Oct. 2, 2003, each of which was filed herewith on Oct. 2, 2003, and incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to a blocking apparatus for lens manufacturing including an automatic wax delivery system, and more particularly to a blocking apparatus for lens manufacturing including an automatic retractable dispensing nozzles for wax delivery.

BACKGROUND OF THE INVENTION

Contact lens manufacturing involves multiple complex operations. Each of these operations requires a high degree of accuracy in order to achieve a precise fabrication for the contact lens.

An unprocessed contact lens is generally known as "button." The button must be precisely aligned to a block, and then fixed to the block using a fixing material such as wax, glue, or other adhesive, so that subsequent machining or other operations on the button can be conveniently performed. This process of fixing a button to a block is referred to as "blocking." A device that performs the blocking must accurately align the button with the block in order to achieve certain optical characteristics of the lens. Precise alignment and positioning of button during blocking reduces prism, increases concentricity of the lens and permits control of the center thickness of the lens.

In conventional systems, a button is typically transferred to a block in such a way that an axis of the button is more or less aligned to an axis of the block. The block is then moved a known distance relative to the button (or vice versa) so as to contact with the button and fix the two together with the adhesive. This process presents problems if the thickness or geometry of the button varies. If the button is too thick, the block may deform the button. If the button is too thin, the block may not achieve sufficient "contact" to achieve proper adherence. In order to compensate these variations, manual adjustments to this distance may be required. These adjustments are time consuming and require a skilled operator.

Furthermore, conventional systems typically dip the block in the fixing material or dispense the fixing material through a nozzle. One problem with these methods is a non-uniform adherence of the wax on the block. In addition, wax left in the nozzle cools, causing it to solidify, particularly at the tip, thereby hampering further wax from being dispensed.

Other drawbacks also exist.

SUMMARY OF THE INVENTION

The invention overcomes these and other drawbacks.

According to one aspect, the invention provides a blocking apparatus and a blocking method for precisely aligning an axis of button with an axis of a block for a blocking process of lens manufacturing.

According to another aspect, the invention provides a button holder for holding a button intact without any risk of potential damage to the button.

In one embodiment, the button holder may operate with a vacuum to hold a button in place on a button placement surface or recess of the button holder.

According to another aspect, the invention provides a button holder coupled to an adjustable offset mechanism for creating a selectable offset between the axis of the button holder and the axis of the block. Adjustable offset mechanism may include an offset device (e.g., screw, cam, etc.) for providing this offset.

According to another aspect, the invention provides a button holder that may be flexibly positioned within a seat aligner. The button holder may include a hole formed therein that receives a button, a body with a slanted surface, and a flange.

According to another aspect, the invention provides a seat aligner that can hold a button holder. The seat aligner may include a chamber formed therein, the chamber may further include a bottom portion for receiving a flange of the button holder and a top portion for receiving the body of the button holder. The bottom portion may include a predefined depth that is larger than the thickness of the flange of the button holder. The top portion may include a surface (e.g., slanted surface) for holding the button holder's body.

In one embodiment, the seat aligner holding a button holder may include at least one adjustment hole for receiving a fastening mechanism that fastens the seat aligner to a seat stage. The adjustment hole of the seat aligner may enable moving the seat aligner within the seat stage while the seat aligner is still attached to the seat stage.

According to another aspect, the invention provides a seat stage having a stage cavity formed therein for receiving a seat aligner. The stage cavity may enable moving the seat aligner within the seat cavity.

According to another aspect, the invention provides a button holder that may flexibly float on a seat stage of a blocking apparatus, where the button holder may include a mechanism to self-align on the seat stage after a block interfaces with the button holder.

According to another aspect, the invention provides a blocking apparatus and a blocking method for automatically compensating variations in a button geometry without requiring complex adjustments during blocking process of lens manufacturing.

In one embodiment, the blocking apparatus may include mechanisms for positioning a block on a button based on a predetermined pressure applied on the block in order to compensate for variations in the button geometry.

In another embodiment, the blocking apparatus may include mechanisms for positioning a block on a button based on a predetermined pressure between the block and the button in order to compensate for variations in the button geometry. In some embodiments, the blocking apparatus may include a sensor indicative of a force between a block and a button.

In another embodiment, the blocking apparatus may include a pressure chamber and a regulator, which are coupled to a block, for regulating a pressure applied on the block.

According to another aspect, the invention provides a blocking apparatus including a mechanism for automatically applying a wax material on a button. In some embodiments, the wax material can be stored within the blocking apparatus.

In one embodiment, the blocking apparatus may include a storage tank. The storage tank may include a reservoir for holding a fixing material and a retractable dispensing nozzle for dispensing the fixing material on a button.

Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings that disclose embodiments of the invention. It should be understood, however, that the drawings are designed for purposes of illustration only and not as a definition of the limits of the invention.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 illustrates a blocking apparatus according to one embodiment of the invention.

FIG. 2 illustrates a block coupled to a block head according to one embodiment of the invention.

FIG. 3 illustrates a seat positioned on a seat stage according to one embodiment of the invention.

FIG. 4A illustrates a seat positioned on a seat stage, where the seat includes a seat aligner and a button holder according to one embodiment of the invention.

FIG. 4B illustrates a button holder positioned on a seat stage according to one embodiment of the invention.

FIG. 5A illustrates an apparatus including an adjustable offset mechanism for creating an offset in the alignment according to one embodiment of the invention.

FIG. 5B illustrates a top view of an apparatus including an adjustable offset mechanism for creating an offset in the alignment according to one embodiment of the invention.

FIG. 6A illustrates a retractable dispensing nozzle in an extended position according to one embodiment of the invention.

FIG. 6B illustrates a retractable dispensing nozzle in a retracted position according to one embodiment of the invention.

FIG. 6C illustrates a storage tank including a retractable dispensing nozzle according to one embodiment of the invention.

FIG. 7 illustrates an alignment of a blocking process according to one embodiment of the invention.

FIG. 8 illustrates a process of aligning a block and a button holder according to one embodiment of the invention.

FIG. 9 illustrates a process of dispensing a fixing material using a retractable dispensing nozzle according to one embodiment of the invention.

FIG. 10 illustrates a pressure based blocking process according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

According to an embodiment of the invention illustrated in FIG. 1, a blocking apparatus 100 of the invention may include, for example, a block 102 (e.g., a fixture, an arbor, etc.), a block head 106, a button 104 (e.g., unprocessed contact lens), a seat 108, a seat stage 110, a base 112, a force control mechanism 114, and a force adjustment mechanism 116. Block 102 may be coupled to block head 106. Block 102 and block head 106 may be movable in an axis vertical to blocking apparatus 100. While block 102 and block head 106 are described herein as operating in a vertical axis, the invention may also be constructed to operate block 102 and block head 106 in a horizontal or any other axis as would be apparent.

According to an aspect of the invention, button 104 is placed on seat 108. Seat 108 may be positioned on and attached to seat stage 110. In some embodiments, seat 108 may be movable in one or more axes relative to seat stage 110.

According to an aspect of the invention, block 102 may be moved vertically to contact button 104. Seat 108 may be moved horizontally (or in some embodiments, vertically) to align an axis of block 102 with an axis of button 104. In some embodiments, these axes may be central axes of the respective components. During the alignment process itself a blocking pin (not otherwise illustrated) is used in place of block 102. Blocking pin may include a pin of substantially identical diameter to that of buttons 104. Blocking pin may also include a block 102 to which a button 104 is already attached in the desired alignment.

According to an aspect of the invention, as illustrated in FIG. 4A, blocking apparatus 100 may include, for example, seat 108 and seat stage 110. Seat 108 may include, for example, a button holder 402 and a seat aligner 404. The combination of button holder 402 and seat aligner 404 illustrated in FIG. 4A is sometimes referred to as a collet. In one embodiment, button holder 402 may include, for example, a top portion 426, a middle portion 428, and a bottom portion 430. Top portion 426 may include, for example, a button receiving surface 425 or recess for receiving button 104. In some embodiments, top portion 426 of button holder 402 may include a surface such as slanted surface 420 for positioning button holder 402 within seat aligner 404. Bottom portion 430 of button holder 402 may include a flange 411.

According to another aspect of the invention, button holder 402 may hold button 104. In some embodiments, button holder 402 may include one or more holes 416 or air-spaces that may assist holding button 104 in place. In some embodiments, button holder 402 may include, for example, one or more holes 416 operating in conjunction with a vacuum that hold button 104. Vacuum or a predefined air pressure inside button holder 402 may enable holding button 104 in place on button placement surface 425.

Seat aligner 404 of seat 108 may include, for example, one or more adjustment holes 408. Adjustment hole 408 may receive a fastening mechanism 406 (e.g., screw, nail, bolt, etc.) for securely fastening seat 108 to seat stage 110. According to one embodiment of the invention, diameter of adjustment hole 408 may be sufficiently larger than diameter of fastening mechanism 406 to enable some movement of seat 108 relative to seat stage 110 when fastening mechanism is loosened. In other embodiments, clamps or clips may be used to fasten seat 108 to seat stage 110, as would be apparent.

Seat aligner 404 may include, for example, a chamber 410 formed therein. Chamber 410 may include, for example, a top portion 420, a middle portion 422, and a bottom portion 424. The top portion 420 of seat aligner 404 may include, for example, a surface such as slanting surface 421 for interfacing with a surface of button holder 402 (e.g., slanting surface 420 of button holder 402). The bottom portion 424 of seat aligner 404 may receive a flange portion of button holder 402. The depth of bottom portion 424 of seat aligner 404 may be larger than the thickness of the flange portion of button holder 402 to accommodate piston-like movement of the flange therein.

According to another aspect of the invention, a vacuum may be used to create a pressure drop inside chamber 410 of seat aligner 404. This pressure drop inside chamber 410 may facilitate disengaging the respective surfaces of button holder 402 and seat aligner 404 during alignment as well as holding button 104 in place during blocking.

According to another embodiment, seat stage 110 may include a stage cavity 414 to accommodate seat aligner 404 as illustrated in FIG. 4A. Stage cavity 414 may permit sufficient movement of seat aligner 404 within seat stage 110 so as to achieve alignment. Stage cavity 414 of seat stage 110 and adjustment holes 408 of seat aligner 404 may assist seat aligner 404