EP1218248A2

EP1218248A2 - Laser-etched pull tab container opening devices and methods of making the same

Info

Publication number: EP1218248A2
Application number: EP01914869A
Authority: EP
Inventors: Joseph W. Stasiuk
Original assignee: Stasiuk Joseph W
Current assignee: STASIUK, JOSEPH W.
Priority date: 2000-03-13
Filing date: 2001-03-12
Publication date: 2002-07-03
Anticipated expiration: 2021-03-12
Also published as: DK1218248T3; WO2001068460A2; ES2300322T3; AU4214001A; AU784218B2; WO2001068460A3; EP1218248B1; ATE381495T1

Abstract

A device and method for opening containers utilizing laser-etched pull tabs and methods of making the same. According to the invention, indicia is laser-etched on a pull tab substrate, which may be made of any suitable material, by selective laser ablation of the substrate with a laser marker. The laser marker is preferably capable of ablating the substrate's surface to any desired depth, including depths of between 1 to 50 microns and depths that enable the etching to be detected by touch. The invention also contemplates removing one or more coating layers in addition to a portion of the exposed pull tabs surface through laser ablation to generate visually contrasting indicia for promoting or decorating the substrate surface. The pull tabs of the present invention have consistent, high definition indicia that is both tamper resistant and permanent.

Description

LASER-ETCHED PULL TAB CONTAINER OPENING DEVICES AND METHODS OF MAKING THE SAME

BACKGROUND OF THE INVENTION

1. Field of the Invention The present application relates to container opening devices and methods of making the same. More particularly, the present invention relates to laser-etched pull tabs and methods of making the same.

2. Description of the Related Technology

Pull tab container opening devices have not been utilized by the food and beverage industry for package enhancement, brand identification, promotional, or informational purposes. Most existing pull tab designs only serve the function of allowing a user to open the container. In recent years, the industry has drifted towards an open, ring-shaped configuration for pull tabs. See U.S. Patent Des. 289,017 and U.S. Patents 4,465,204 and 4,530,631. These tabs are preferred not only because they have an aperture for accepting the finger of a user (which aids the opening process), but also because they allow the industry to use less material in producing the tabs. However, ring-shaped tabs have proven ineffective for accepting indicia thereon, (whether produced by ink-jet printing, stamping, mechanical etching, or otherwise), due to the limited surface area of the tab.

To overcome the surface area problem, some prior artisans have attempted to place promotional pieces in the finger hole of prior art tabs but have had limited success due to the relative expense and slowness of such plug operations. See U.S. Patents 3,958,354 and 5,191,695.

Other artisans have attempted to use a closed-tab configuration to provide additional surface area for accepting promotional or decorative materials thereon. See U.S. Patent 4,363,179. The prior art teaches that closed-end tabs can receive ink-jet printing to place indicia on the tab. See Australian Patent 81794/94. However, ink-jet printing of a pull tab requires application of ink after the pull tab is fully formed and exits the conversion press because the temperatures within the press would cause the solvent-based carrier of the pigment to ignite. Such post production marking has not attracted any interest in the industry due to its prohibitive expense. In addition, even if pre- arked tab stock was sent into a conversion press, the temperatures therein and the mechanical deformation of the flat stock taking place therein would severely alter or destroy any pre-existing markings.

Furthermore, ink-jet printing lacks both predictability and permanence. For example, the inability to repeatedly produce the same clear image on a small substrate is systemic in the ink-jet process. Inks are also easily removed from most substrates by everyday solvents. Taken in combination, counterfeiters could easily remove any contest- based indicia from a pull-tab and apply their own ink indicia in place thereof; making such contests impractical for ink-jet printed tabs. Accordingly, ink-jet printing has proven not only logistically and technically prohibitive but also unduly costly and of limited utility.

The foregoing underscores the problems associated with conventional prior art tabs and methods of decorating the same. Furthermore, the foregoing highlights the long, yet unresolved need in the art to provide an effective and cost efficient means of providing container opening devices having high definition and permanent indicia for informational, promotional or decorative purposes.

SUMMARY OF THE INVENTION

The present invention overcomes the practical problems described above and offers new advantages as well. The present invention is based on the realization that laser-etching pull tabs to a depth that ablates a portion of the tab substrate provides consistent, high- definition indicia which is surprisingly tamper-resistant and permanent. In order to overcome the aforementioned deficiencies of the prior art, Applicant previously disclosed a method of providing coated tab stock in which decorative, promotional, or informative indicia is laser-etched thereon. For example, Applicant's previous applications: U.S. Serial No. 08/917,516, filed August 26, 1997 and U.S. Serial No. 09/061,227, filed April 17, 1998, which are hereby incorporated by reference in their entirety, teach laser-etching pull tabs in order to provide high definition, high clarity indicia thereon.

Applicant's previous applications highlighted Applicant's then preferred embodiments wherein pull tabs having one or more coating layers had portions of such layers selectively removed to form indicia on said pull tab. According to the invention a pull tab is provided having selective removal of not only the coating layer or layers, but also a portion of the substrate itself. According to Applicant's presently preferred method of laser engraving a coated pull tab, the substrate itself may be permanently etched with at least a portion of the intended indicia, thereby preventing counterfeit or easy disfiguration of the pull tab ' s indicia.

Furthermore, according to the invention, laser ablation of a portion of the substrate allows for an uncoated pull tab to be etched with a laser to create a visually contrasting image due to the sublimation and oxidation of the substrate. Also, according to a related aspect of the invention, laser ablation of the substrate surface to a specified depth allows for a physical relief of the substrate whereby the indicia is not only visible but also detectable by touch. For example, according to the invention, braille language letters can be etched into the tab to identify the contents of the container.

According to the invention, and as will be appreciated by one of ordinary skill in the art armed with Applicant's specification, the substrate can be ablated or etched to any desired depth.

In accordance with one aspect of the invention, there is provided a pull tab container opening device having informational, promotional or decorative materials laser ablated into the surface of the pull tab substrate. According to another aspect of the invention, there is provided a pull tab container opening device having at least one substantially permanent coating layer thereon and having informational, promotional or decorative materials thereon, wherein said materials are formed by the selective laser removal of at least a portion of said coating layer and a portion of said substrate. In accordance with another aspect of the present invention, there are provided methods of making the aforementioned pull tab container opening devices having laser etched indicia thereon.

The pull tabs of the present invention may be made of any suitable material which is capable of functioning of as a pull tab for a container including aluminum, steel, plastic, other metals, and/or any natural, synthetic, composite, or other suitable material. The selection of suitable materials are well within the ability of one of ordinary skill in the art. The tabs may also include a ring-shaped aperture for receiving the finger of a user. Construction of suitable pull tabs according to the invention is well within the ability of one of ordinary skill in the art. The invention should not be understood as being limited by the shape, size or material of the pull tab substrate.

In accordance with a presently preferred embodiment, there is provided a pull tab comprising an aluminum alloy wherein said tab is contacted with the emission of an optical device capable of ablating the surface of said tab such that the surface of said tab is permanently etched. The etching may be of any depth desired. Preferable depths are between 5 and 50 microns, and more preferably, between 15 and 30 microns.

In accordance with another presently preferred embodiment, there is provided a pull tab having a coating layer thereon, wherein said pull tab has indicia generated thereon by the laser ablation of a portion of a said coating layer to reveal at least a portion of said substrate which is also selectively ablated by the laser to any suitable depth. In accordance with yet another presently preferred embodiment, there is provided a pull tab having a plurality of coating layers thereon. In accordance with this aspect of the invention, the pull tab according to the invention has an image of multiple colors generated thereon, wherein said image is generated by the selective removal (through selective laser ablation) of said coating layers and the surface of said substrate such that at least a portion of said image is permanently etched in said substrate to a desired depth.

Suitable coatings for pull tabs according to the invention include any coatings capable of selective removal by laser ablation. In accordance with one aspect in the invention, the coatings used on a substrate should be more susceptible to laser ablation, by sublimation or otherwise, than the surface of the substrate. Thus, the operator of a laser etching apparatus according to the invention, can remove the coatings without affecting the surface of the pull tab unintentionally.

Representative coatings include those readily accessible by those of ordinary skill in the art. For example, Alcoa supplies tab stock with suitable coatings supplied by Dexter, Balspar, BASF, and numerous others. The coating type is not limited to epoxy, vinyl or other organic coating. It may be preferable to use a coating that contrasts with the underlining substrate, which may be aluminum, other materials, or another coating layer. In addition, multiple layers of contrasting coatings may be used so that selective removal of portions of the layers may reveal a multiple color design. The present invention should not be understood to be limited by the number or color of coatings supplied, nor by the substrate to which indicia is to be applied.

The present invention is also not limited by the laser-etching method used to decorate pull tabs according to the invention. As will be appreciated by one of ordinary skill in the art, there are a variety of methods of generating images on a substrate via laser. All of such methods are equally understood as being within the scope of the invention.

One presently preferred method for laser-etching a design into a pull tab is computer-aided laser etching. In accordance with this method, a design is laser-etched into a substrate with the aid of a computer and computer peripherals, wherein the laser-etching device is controlled by a computer program which controls the orientation and path of the laser beam to generate an ablated pattern. Any laser device suitable for computer-aided laser etching may be used according to the invention. The work piece, in this case a pull tab, preferably includes a surface upon which a single layer or multiple layers of coating material, such as an oxidizable paint or organic coating, has been applied. According to the present invention, a presently preferred method is performed by the following steps: a design is input into a computer memory by use of a scanner or other input device; the design is then scaled to the desired size; the intensity of the laser beam is selected so that only the desired layer or layers of material are removed to a specific depth; and the control program is allowed to direct the laser beam to etch away appropriate portions of the layer or layers of the ablatable materials, thus exposing and/or etching the underlining surface or coating to form the desired image. In accordance with this method, multiple color and multiple layer designs may be formed by programming the laser beam to remove different portions and depths of each layer to create a multi-colored or multi- layered design.

In accordance with this aspect of the invention, a presently preferred embodiment involves use of a yttrium aluminum garnet ("YAG") laser marker. The YAG marking process works by steering the laser beam with a pair x and y galvanometers which are controlled by software and hardware interfaces. In accordance with this embodiment of the invention, indicia are inscribed on to the substrate with extremely fine resolution and clarity, thereby providing striking contrast and resolution as compared to prior art ink- printed substrates.

Another presently preferred method for laser-etching a design into a pull tab is mask-etching. In accordance with this method, CO₂ lasers, or other similar high gain optically pumped laser devices, suited for laser marking may be used. CO₂ and like lasers, may use a mask or stencil for etching purposes. In accordance with this aspect of the invention, a presently preferred embodiment contemplates use of a laser device in which a mask defining a desired pattern is placed in the laser's optical cavity. The output power or energy emanating from the laser should be sufficient to affect physical alterations of surfaces such that the desired pattern from the mask is engraved into the surface of the substrate contacted by the output of the laser device. Alternatively, the mask structure may be disposed between the output of the laser device and the surface of the substrate anywhere along the output's path. Accordingly, one of ordinary skill in the art will appreciate that various configurations of where the mask or stencil is positioned between the laser source and the substrate surface are within the scope of the invention.

As will be appreciated by one of ordinary skill in the art, suitable mask structures include those having cut-out portions defining the desired pattern to be engraved on the substrate. Furthermore, one of ordinary skill in the art will appreciate that equivalent patterns can be formed by providing masks having portions that are simply transmissive to the particular wave length of laser light involved. Accordingly, the term "cut-out portions" is meant to include any equivalent means of defining patterns on the mask such that the pattern is capable of being etched into the surface of the substrate being worked upon. Generally, mask structures are used with lasers when a pattern having a uniform depth is desired. Mask structures are not as susceptible to altering the intensity or depth of various portions of the indicia to be generated on a substrate. However, as will be appreciated by one of ordinary skill in the art, multiple masks andor multiple laser devices may be used for generating indicia having varying depths of ablation or multiple layers to be selectively ablated. A presently preferred embodiment involves a single mask and a single layer whereby a coated pull tab has the pattern of the mask ablated through the coating layer and into the substrate to a depth of up to 30 microns. Such an embodiment allows for the rapid engraving of numerous tabs at production speeds. Accordingly, CO₂ laser etching is primarily suited to generating indicia on pull tabs having a single coating layer or having no coating layer at all. However, as will be appreciated by one of ordinary skill in the art, assembly-line type laser etching stations may be set up along the production line such that as a substrate passes each station a different portion of the indicia is quickly laser-etched onto the substrate.

The invention as described and claimed herein should become evident to a person of ordinary skill in the art given the following enabling description and drawings. The aspects and features of the invention believed to be novel and other elements characteristic of the invention are set forth with particularity in the appended claims. The drawings are for illustration purposes only and are not drawn to scale unless otherwise indicated. The drawings are not intended to limit the scope of the invention. The following enabling disclosure is directed to one of ordinary skill in the art and presupposes that those aspects of the invention within the ability of the ordinarily skilled artisan are understood and appreciated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a top view of an aluminum can top according to one embodiment of the invention.

FIG.2A shows a substrate having a coating layer and a design laser-etched thereon according to one embodiment of the invention. FIG. 2B shows a substrate having multiple layers and having a multi-layer design laser-etched thereon according to one embodiment of the invention.

FIG. 3A-B are photomicrographs of a prior art, Inkjet printed aluminum can.

FIG. 4A-B are photomicrographs of a laser-etched coated aluminum substrate according to one embodiment of the invention. FIG. 5A-C are photomicrographs of a laser-ablated surface of an aluminum substrate according to one embodiment of the invention.

FIG. 6 is a top view of an apparatus for manufacturing laser-etched pull tabs according to one embodiment of the invention.

FIG.7 is atop view of an alternative apparatus for manufacturing laser-etched pull tabs according to another embodiment of the invention.

FIG. 8 is a top view of another alternative apparatus for manufacturing laser-etched pull tabs according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a novel, laser-etched container opening device according to the present invention. As depicted on FIG. 1, a representative aluminum can top 120, or other container top, is provided for receiving a container opening device. Can tops, or container lids, are typically formed into a desired shape for receiving a container opening device and for attachment to a container body within a conversion press (not shown). During the can top formation process, various bubbles and deformations known as "coins" are imparted into the can top in order to enhance the strength thereof. The can top of FIG. 1 shows typical anti-buckle coins 121 produced within the conversion press. An additional coin 126 is also shown on FIG. 1. The can top also includes a top opening score 122 to allow the container to be opened by a user, and a top rim 123 tq allow the top to be attached to a suitable container body. Other deformations 127 may also be present in the scored panel 128 to help provide access to the contents of the container. Preferably, there is an interruption (not shown) in the path of the top opening score 122 surrounding the panel 128 so that the panel 128 remains attached to the can top 120 after opening.

To aid the opening of the container by a user, a pull tab 124 is provided for actuation by the user. As will be appreciated by one of ordinary skill in the art, pull tabs are typically formed from a thin sheet of tab stock material in a conversion press. In a conversion press, various cutting and stamping dies operate on the sheet of tab stock material to form a sheet of pull tabs capable of being pulled from the sheet and attached to a container top. For example, as depicted on FIG. 1, a tab 124 may be riveted, or staked, onto a button 125 in the can top by a re-strike action of the conversion press.

As depicted on FIG. 1, today's typical pull tab comprises a grab portion 129 and a nose portion 130. The grab portion 129 may be lifted to force the nose potion 130 into intimate contact with the scored panel 128. When the pressure of the nose portion 130 against the scored panel 128 is sufficient, the opening score 122 tears and the panel 128 may be folded down to allow access to the contents of the container. Preferably, an interruption (not shown) in the opening score 122 prevents the panel 128 from detaching from the can top 120 and falling into the container. As shown on FIG. 1 , a slit 131 may be advantageously provided in the pull tab 124 in order to facilitate its action as a lever with the staked button 125 acting as a fulcrum connection point. As will be appreciated by one of ordinary skill in the art, almost any tab of any size, shape, or configuration may be suitable for use in the present invention.

According to the embodiment depicted in FIG. 1, the grab portion is preferably configured to not include an aperture for accepting the finger of a user, but rather configured to be a "closed-tab." Such a closed-tab configuration provides additional surface area upon which to apply promotional, informational or decorative materials. For example, the pull tab of FIG.1 exhibits a decoration 132 illustrated as a "value mark" logo.

According to the invention, the decoration 132 is laser-etched into the surface of the pull tab substrate. The term "laser-etching" is intended to mean the process by which a selective portion of a material is removed by contact with a laser beam to form a desired pattern of a desired depth by localized sublimation, evaporation, burning, oxidation, or other process, of the contacted material or materials. Thus, for example, as depicted in the embodiment of FIG. 1, the logo "value mark" and the border surrounding the logo are preferably the result of the surface of the pull tab being contacted by the beam of a laser such that the contacted area is ablated in a predetermined pattern to a predetermined depth. In the case of a presently preferred substrate, an aluminum pull tab, such ablated areas achieve, quite unexpectedly, remarkably visually-contrasting images due to the oxidation and sublimation of the substrate. In other words, the ablated areas are of a surprisingly different shade and/or color than the untreated areas. Such a stark visual contrast in color is not achievable by mechanical etching, stamping or chemical engraving of aluminum pull tabs. Furthermore, as will be appreciated by one of ordinary skill in the art, laser-etching allows images to be generated on substrates to almost any resolution; visually perceptive or otherwise. Such resolution is likewise not reliably achievable by prior art methods.

The visual contrast achievable through laser-etching techniques can also be used to provide informational, promotional or decorative materials onto other parts of the container. For example, as depicted in FIG. 1 , the can decoration 133 "brand equity" is etched directly into the can top 120. Such can decorations are preferably generated on can tops that have a colored coating on, or pigment in, the aluminum (or other material) of the top, because the visual contrast and the striking clarity systemic in the laser-etching process are even more striking.

Furthermore, laser-etched pull tabs according to the invention are preferably etched to a predetermined depth whereby a physical relief which may be detectable to the touch is generated on the pull tab. In a presently preferred embodiment such as where the substrate to be etched is an aluminum pull-tab container opening device for an aluminum beverage can, the etching is preferably to a depth of from about 5 microns to 50 microns, and more preferably from about 15 microns to about 30 microns. As will be appreciated by one of ordinary skill in the art, controlling the depth to which a laser ablates the surface of a substrate is dependent upon, and can be controlled by, the manipulation of multiple factors. For example, each of the type, power and contact time of the laser device allow the user to effect the depth of the etching. Also, for example, the type of substrate, coating, etc. allow the user to predetermine the depth of etching through trial and error or otherwise.

Furthermore, as will be appreciated by one of ordinary skill in the art upon reading Applicant's specification, once the workpiece materials and process parameters are set, laser-etching allows for rapid, high volume production of products having virtually identical, highly-resolved indicia generated thereon. Such predictability and repeatability are not achievable by prior art printing techniques.

Two presently preferred laser-etching methods are computer-aided laser etching and mask etching. As will be understood by one of ordinary skill in the art, computer-aided etching typically entails the use of a computer and computer peripherals to control the orientation, path, and/or power of a laser's beam to generate an ablated pattern on a workpiece. According to a preferred method, a design is input into the memory of a computer through either a scanner, a keyboard, both, or any other device or method of inputting a design known in the art. The computer may then communicate the design to a laser engraving device which engraves the design onto the workpiece by use of the devices laser beam. The choice of a suitable laser device is well within the ability of one of ordinary skill in the art. A presently preferred embodiment makes use of a YAG laser device, and more preferably a 120 watt Nd: YAG laser device having a 530 nm wavelength.

According to this method, the computer may be a typical personal computer, such as an IBM 486, Pentium or like computer, which has been programmed with a laser control program. For example, such a laser control program is the LUMONICS SOLO user interface software which is available with a LUMONICS LIGHTWRITER SPE laser engraving device. It should be understood that other brands and models of control software, engraving devices, etc., whether presently existing or not, which are capable of performing the method described herein are within the scope of the invention, and that the brands and models discussed are by way of example only and should not be deemed to limit the scope of the invention.

In operation, an operator enters an input design, such as "value mark" into the memory of a computer. The design may be entered into the memory of the computer by scanning the image into a scanner or by typing, or both, or otherwise entering the image with a computer keyboard. Preferably, the operator may be able to modify the input design in a variety of ways. For example, it is presently preferred that the operator be able to scale the design by any conventional technique such that the whole, or any part, of the design is capable of being made larger or smaller, or such that multiple images may be combined in whole or in part.

The workpiece is then placed in a position that is within the path of the laser beam. The intensity of the laser beam is adjusted so that the etching will be to a proper, predetermined depth. The laser beam is then controlled by the computer to etch the design into the workpiece. According to a presently preferred method, computer control of the laser beam involves software and hardware interfaces which control a pair of X and Y galvanometers which steer the laser in a path corresponding to the output design. The output design etched should reflect the input design and any modifications made by the operator. As will be appreciated by one of ordinary skill in the art, the depth of the etching may be controlled by various means. A presently preferred method of controlling the depth of the etch is by varying the intensity of the beam. It is well within the ability of one skilled in the art to know, or learn through trial and error or otherwise, the proper settings for the particular laser and laser beam utilized in view of the particular workpiece involved.

Alternatively, the laser etching may be effectuated by the mask-etching method. As will be appreciated by one of ordinary skill in the art, this method typically involves shining a laser beam through a mask, and possibly other peripherals, prior to contacting the surface of a workpiece. The choice of a suitable laser device for this method of etching is well within the ability of the ordinarily skilled artisan. Presently preferred devices include high gain pump devices such as CO₂ lasers. The mask material should be capable of resisting penetration of the laser beam. The mask may be disposed within the lensing-system of the laser source, at the output point of the laser device, or otherwise disposed along the path of the laser beam. Alternatively, the mask may operate as a stencil which sits against the workpiece during the marking process. The mask typically includes cut-out portions in the shape of the desired image, whereby the only portions of the beam penetrating the mask are those in the shape of the desired image. As will be appreciated by one of ordinary skill in the art, suitable mask structures include not only those having cut-out portions defining the desired pattern to be engraved on the substrate, but also those that have portions that are simply trans issive to the particular wave length of laser light involved. Accordingly, the term "cut-out portions" is meant to include any equivalent means of defining patterns on the mask such that the pattern is capable of being etched into the surface of the workpiece being worked upon.

Generally, mask structures are used with suitable lasers when a pattern having a uniform depth are desired because mask structures are not as susceptible to altering the intensity or depth of various portions of the indicia to be generated on a workpiece. However, as will be appreciated by one of ordinary skill in the art, multiple masks and/or multiple laser devices may be used for generating indicia having varying depths of ablation or multiple layers to be selectively ablated. A presently preferred embodiment involves a single mask and a single layer whereby a coated pull tab has the pattern of the mask ablated through the coating layer and into the substrate to a depth of up to 30 microns. Such an embodiment allows for the rapid engraving of numerous tabs at production speeds. Accordingly, mask-etching with a CO₂ or like laser is primarily suited to generating indicia on pull tabs having a single coating layer or having no coating layer at all.

Regardless of what type of laser etching is used, a presently preferred embodiment of the invention utilizes a pull tab having at least one coating layer thereon. FIG. 2A depicts a single coating layered, laser-etched substrate according to the invention. In the embodiment depicted in FIG. 2A, there is provided a substrate 150 having a coating layer 151 thereon. Presently preferred coating layers include those readily accessible by those of ordinary skill in the art. For example, Alcoa supplies tab stock with suitable coatings supplied by Dexter, Balspar, BASF, and numerous others. The coating type is not limited to epoxy, vinyl or other organic coating. In accordance with this embodiment of the invention, the coating layer 151, and at least a portion of any part of the substrate 150 revealed thereunder, are laser-etched to provide a permanent etched-area 160 capable of defining an exceptional, visually striking image for promoting or decorating the container. As will be appreciated by one of ordinary skill in the art, the workpiece materials and process parameters can be chosen to cause ablation of the surface(s) of the coating layer(s) and substrate to be ablated in almost any desired pattern, to almost any desired depth. According to an advantageous embodiment, the substrate 150 may be an aluminum tab, or some other container opening device to be decorated or marked. According to this embodiment, this substrate is an opening device for a food or beverage container, however, any other suitable substrate may also be marked. Presently preferred substrates may be made of any suitable material and may form a part of a pull tab, can top, bottle cap, container lid, or any other portion of a container device.

According to the invention, the substrate may be coated with more than one layer. FIG. 2B shows four layers of coatings on the substrate 150. As discussed above, coatings are preferably materials capable of laser ablation and more preferably, materials more susceptible to laser ablation by the intended laser than the underlying substrate or underlying layers and substrate. Presently preferred coating layers include those readily accessible by those of ordinary skill in the art. For example, Alcoa supplies tab stock with suitable coatings supplied by Dexter, Balspar, BASF, and numerous others. The coating type is not limited to epoxy, vinyl or other organic coating.

The coatings may be of any suitable colors. Preferably, the coatings are of visually differing or contrasting colors such that a multi-colored image may be created. By way of example, the multi-coated substrate of FIG. 2B may comprise a cyan layer 151 , a magenta layer 152, a yellow layer 153, and a black layer 154. When the substrate is aluminum, a removal of all four layers, such as an area 155 reveals a natural aluminum color. Area 156 shows the removal of three layers revealing a cyan color. Area 157 shows the removal of two layers revealing a magenta color. Area 158 shows removal of a single layer revealing a yellow color. In this fashion virtually any color can be generated. Furthermore, in accordance with the invention, area 159 shows not only the removal of all four layers, but also the partial ablation of a portion of the substrate to a desired depth. By such ablation of the substrate, a permanent etched-area 160 may be created. Such an area will continue to serve to identify the tab even if the layers (151 , 152, 153, 154) are removed by chemical means, physical means, or otherwise. As will be appreciated by one of ordinary skill in the art, such permanent ablation of the surface of a substrate can serve to prevent counterfeiting or prolong the informational, promotional or decorative power of the substrate. Permanence in the presence of chemical solvents is only one advantage of the present invention over more conventional methods of marking aluminum or other types of substrates with colors. For example, in the aluminum can industry, ink-jet printing is occasionally used to place source and date indicia on the bare aluminum of the underside of the can. FIG. 3A and FIG. 3B are photomicrographs of the ink-printed characters applied to the underside of a "Mountain Dew" soda can (produced by Pepsi-Cola Company). FIG. 3 A and 3B were taken by a Scanning Electron Microscope ("SEM") at 15X and 30X, respectively. The solid line at the bottom right of the micrographs represents a length of one hundred microns. By contrast, FIG. 4A and 4B are photomicrographs at 15X and 30X, respectively, of a laser-etched coated aluminum substrate according to the invention. More specifically, FIG.4A-B are photomicrographs of a piece of 5052H19 aluminum-alloy substrate having a 3msi (about 1.9 micron thick) Valspar 26839-803 black epoxy coating which was treated at production speeds with a 120 Watt-powered, Nd: YAG- type laser, having a 530 nm wavelength.

Comparing FIGs. 3A-B to FIGs. 4A-4B reveals that typical laser ablation craters generated by a Nd:YAG or similar laser are only approximately 60 microns in diameter, which is a full magnitude of difference smaller in size than a typical ink dot (which averages between about 600 to 700 microns) of an ink printing process. Accordingly, as will be appreciated by one of ordinary skill in the art, the resolution and clarity capable of being generated by laser etching is also a full magnitude of difference better than that of the ink printing process.

Also revealed is the fact that typical laser ablations are substantially uniform in shape, surface area and appearance; whereas ink dots are non-uniform in shape, surface area and appearance (which adversely affects clarity and resolution). Accordingly, as will be appreciated by one of ordinary skill in the art, laser etching inherently results in an image having better resolution and sharpness. Furthermore, typical laser ablations are extremely precise in location and predicable in occurrence, thereby promoting a visually uniform and virtually uninterrupted pattern of ablations as compared to the spotty deposition of ink dots which is systemic in the ink printing process. In addition, laser ablations allow for a visually clear demarcation between the color-coated area and the laser-treated area as compared to the unpredictable contours and ink-concentration of ink dots generated in the ink printing process.

Furthermore, as discussed above, the laser etching process provides for a substantially permanent image when the substrate itself is ablated to any suitable or desired depth, as compared to the more easily removed (whether physically removed or chemically removed) ink generated image of the ink printing process, which is inherently incapable of accumulating at any appreciable thickness above the surface of the substrate due to its solvent-carrier base. FIGs.5A-C are micrographs of the embodiment of FIG.4 at differing positions and resolutions. As shown in the photomicrographs, the surface of the aluminum substrate below the coating may be ablated to a predetermined depth. In a presently preferred embodiment, the substrate is etched to a depth of about 5 to about 50 microns, more preferably a depth of about 15 to about 30 microns. The substrate of FIG. 5 is ablated to a presently preferred depth of about 30 microns.. In view of the foregoing enabling disclosure, one of ordinary skill in the art will appreciate that laser-etching substrates such as pull tabs according to the invention overcomes many of the shortcomings and limitations of the prior art, and satisfies a long- felt, yet unresolved need. As will be appreciated by one of ordinary skill in the art, laser-etching processes can be carried out at any suitable stage of an article of manufacture's life-span. For example, with pull tabs, the laser-etching process may be carried out prior to, during, or after a tab stock material is formed into pull tabs and connected to the top of a container. A representative apparatus for manufacturing pull tabs according to the invention is depicted in Figures 6-8. In a first embodiment, as shown in FIG. 6, the apparatus comprises a modified conversion press 70. Typical conversion presses for the manufacture of prior art tabs are commercially available from such companies as Burderer or Minister. The modified press 70 includes a container end conveyer 71 for transporting container ends through the press 70. The container end conveyer 61 has an inlet 72 for accepting untabbed container ends and an outlet 73 through which tabbed container ends may be collected. The conveyer 71 transports container ends from the inlet 72, through the press 70, to the outlet 73, where tabbed container ends may be collected.

As depicted in FIG. 6, the press 70 also includes a tab stock inlet 74 and a formed tab strip outlet 76. Interposed between the tab stock inlet 74 and tab strip outlet 76, and trans versing the conveyer 71, is a die area 75. As generally known in the art, the die area 75 comprises a plurality of cutting and stamping dies (not shown) which operate to form and shape materials pressing therethrough into a desired configuration. The die area 75 may treat container ends as they pass through the die area 75 on conveyer 71. According to the invention, tab stock 90 may enter the press 70 through the tab stock inlet 74. As depicted in FIG. 6, a strip of tab stock 90 enters through the inlet 74 and then passes into the die area 75 where it is cut and shaped into formed tabs. The formed tab strip 91 may then exit the press 70 through formed tab strip outlet 76.

In a preferred embodiment, the die area 75 is composed of a plurality of interchangeable cutting dies and stamping dies. As will be appreciated by one of ordinary skill in the art, interchangeable parts allows a single press to be used in manufacturing a plurality of differently shaped tabs comprised of a plurality of different materials. For example, the die could be rigged to produce a tab lacking a finger aperture by removing or blocking the aperture cutting dies. Accordingly, numerous other modifications to the die area to produce differently configured tabs can be fully appreciated by the skilled artisan in view of Applicant's specification.

The formed tab strip 91 after exiting the press 70 through formed tab strip outlet 76 may reenter the press 70 through the formed tab strip inlet 77. The formed tab strip 91 is then fed into a riveting area 78 adjacent the conveyer 71. In the riveting area 78 formed tabs are removed from the formed tab strip 91 and riveted to container ends entering the riveting area 78 via the conveyer 71. The formed tab strip scrap 92 then exits the riveting area 78 and, ultimately, the press 70 through the tab scrap outlet 79. Container ends exit the riveting area 78, having tabs riveted thereto, by means of the conveyer 71. The conveyer ultimately feeds the tabbed container ends out of the press 70 at the conveyer outlet 73 where the container ends may be collected. The tab strip scrap 92 exiting the tab scrap outlet 79 may also be collected and used for other purposes, such as being recycled into fresh tab stock 90.

Tab stock 90, according to the invention, may comprise any material capable of use as a pull tab container opening device. Exemplary materials include aluminum, steel, plastic, or any natural, synthetic, composite, or other suitable material. Similarly, combinations of materials as layers or otherwise may also be used. Accordingly, one of ordinary skill in the art will understand that corresponding manipulation of the modified press 70 may be necessary to accommodate different materials. In a preferred embodiment, the tab stock 90 comprises aluminum. As depicted in

FIG. 6, aluminum tab stock strips may be any suitable width and of any desired length. Generally, existing presses accommodate tab stock of either 1.9 or 2.8 inches in width and .009-.010 inches in depth. According to the present invention, the depth of the stock can be increased, depending on the strength desired and the material used. A preferred embodiment contemplates an aluminum strip of about 1 -3 inches in width and about .0125 inches in depth.

Colored tab stock 90 may be used with the present invention if colored tabs are desired. To effectuate the coloring, pigmentation may be used while forming the tab stock 90, or alternatively, the tab stock 90 may be coated with a colored material. Similarly, as will be appreciated by one of ordinary skill in the art, other colored or coated materials, such as plastics, may be used.

To further enhance the decorative or symbolic power of the tabs, a laser-etching station 100 may be used. The laser-etching station 100 may be an area within the modified press 70. Alternatively, the laser-etching station 100 may be located outside the press 70, although it may still be in-line or integral with the press 70.

In a preferred embodiment as depicted in FIG. 6, the laser-etching station 100 is located at an area whereby the tab stock 90 can be decorated prior to entering the tab stock inlet 74. The laser-etching station 100 may be integral with the feed mechanism that feeds tab stock 90 into the tab stock inlet 74; or alternatively, the laser-etching station 100 may be situated at a location for treating tab stock 90 which is not even housed in the area where the press 70 is located. In other words, the tab stock 90 may be decorated and then brought to a location housing a press 70.

FIG. 7 depicts an alternative embodiment of an apparatus for manufacturing pull tabs in accordance with the present invention. With reference to FIG. 6, like reference numerals refer to the same elements; however, in this embodiment the laser-etching station 100 is located outside the press 70 but in-line with the tab stock 90 such that the formed tab strip 91 exits the press 70 at tab strip outlet 76 and then passes through laser-etching station 100 prior to reentering the press 70. Although it is contemplated that the laser-etching station 100 may perform all of the decorating functions within the scope of the invention no matter where it is housed, placement of the laser-etching station 100 in-line and capable of receiving the formed tab strip 91 is a presently preferred process. First, the tabs are already formed in the strip which may enhance the speed and ability of the apparatus, through mechanical orientation or computer recognition, or otherwise, to provide substantially the same tab decorations on each tab. Secondly, the laser-etching station 100 may be used in connection with an accumulator (not shown) that may be used to allow the die area 75 to operate at a faster pace than can be accommodated by the laser-etching station 100. FIG. 8 depicts another alternative embodiment of an apparatus for manufacturing tabs in accordance with the present invention. With reference to FIG. 6 and 7, like reference numerals refer to like elements; however, the laser-etching station 100 in FIG. 8 is located at an area for receiving tabbed container ends exiting the conveyer 71 at the conveyor outlet 73. In the specific embodiment depicted in FIG.8, the laser-etching station 100 is of a generally cylindrical shape. Disposed within the laser-etching station 100 is a cylindrical track 101 for accepting a plurality of tabbed container ends. The laser-etching station 100 also has an interior section 102 encircled by the cylindrical track 101.

In this embodiment, tabbed container ends exit the conveyor 71 at the conveyor outlet 73 and are received by the cylindrical track 101 of the laser-etching station 100. The track 101 may be rotated in either direction such that the container ends may be rotated to or through one or more stations. With this arrangement, different tab decorations can be etched onto the tabs, or container ends, at different stations. Laser etching equipment may be disposed within the interior section 102 of the laser-etching station 100 and/or located on the outer perimeter of the track 101. This embodiment may be preferred, or in combination with the previous embodiments, if decorations are to be supplied not only to the tabs, but also to the container ends.

The laser-etching station 100 of the present invention may be configured in any manner suitable for etching the tab stock, formed tab strip, or tabs before or after attachment to the container. The exact layout and design of the laser-etching station will vary according to the methods and materials to be used. The laser-etching station may further comprise an apparatus for embossing, debossing, inscribing or etching tab decorations, or any combination thereof. Similarly, the laser-etching station may comprise alone, or in combination with the above, any apparatus suitable for printing, screening, painting, adhering, gluing or otherwise placing or generating tab decorations on tabs or tab- making materials.

The laser-etching station may make use of mechanical orientation or computer controlled artificial recognition systems to help ensure that the tab decorations appear substantially the same on the end product. It is also within the scope of the invention to make use of a plurality of laser-etching stations, for example, a combination of FIGs. 6-8. It is understood that many modifications to this invention may be made without departing from the spirit of the invention. The appended claims express the scope of the invention.

Claims

I claim:

1. A container opening device comprising: a pull tab having an attachment point for attachment to a container; said pull tab having a grab portion oriented to one side of said attachment point and a nose portion oriented on an opposite side of said attachment point, said pull tab actuatable to pen the container; a laser-etched image defined on said pull tab; wherein said image is created by selective, laser ablation of a portion of said pull tab.

2. The container opening device of claim 1 , wherein said pull tab comprises a material selected from the group consisting of metals and plastics.

3. The container opening device of claim 2, wherein said material is metal.

4. The container opening device of claim 3, wherein said metal is aluminum.

5. The container opening device of claim 4, wherein said pull tab is ablated to a depth of between about 1 micron and 50 microns.

6. The container opening device of claim 5, wherein said pull tab is ablated to a depth of between about 15 microns and 30 microns.

7. The container opening device of claim 6, wherein said selective laser ablation is performed by computer-aided laser-etching.

8. The container opening device of claim 7, wherein said computer-aided laser-etching is carried out by a Nd: YAG laser.

9. The container opening device of claim 6, wherein said selective laser ablation is performed by mask-etching.

10. A container opening device comprising: a pull tab having an attachment point for attachment to a container; said pull tab having a grab portion oriented to one side of said attachment point and a nose portion oriented on an opposite side of said attachment point, said pull tab actuatable to pen the container; a coating layer disposed on said pull tab; a laser-etched image defined on said pull tab; wherein said image is created by selective laser removal of a portion of said coating layer and selective laser ablation of a portion of said pull tab exposed by the selective removal of said coating layer.

11. The container opening device of claim 10, wherein said pull tab comprises a material selected from the group consisting of metals and plastics.

12. The container opening device of claim 11, wherein said material is metal.

13. The container opening device of claim 12, wherein said metal is aluminum.

14. The container opening device of claim 13 , wherein said pull tab is ablated to a depth of between about 1 micron and 50 microns.

15. The container opening device of claim 14, wherein said pull tab is ablated to a depth of between about 15 microns and 30 microns.

16. The container opening device of claim 15, wherein said selective laser ablation is performed by computer-aided laser-etching.

17. The container opening device of claim 16, wherein said computer-aided laser- etching is carried out by a Nd: YAG laser.

18. The container opening device of claim 17, wherein said selective laser ablation is performed by mask-etching.

19. A container opening device comprising: a pull tab having an attachment point for attachment to a container; said pull tab having a grab portion oriented to one side of said attachment point and a nose portion oriented on an opposite side of said attachment point, said pull tab actuatable to pen the container; two or more coating layers disposed on said pull tab; a laser-etched image defined on said pull tab; wherein said image is created by selective laser removal of portions of said coating layers and selective laser ablation of a portion of said pull tab exposed by the selective removal of said coating layers.

20. A method of manufacturing a laser-etched pull tab container opening device comprising the steps of: providing a portion of tab stock; forming said tab stock into a pull tab adapted for actuatable attachment to a container; laser ablating a surface of said pull tab to a predetermined depth of between 1 and 50 microns to generate substantially permanent indicia on said pull tab.

21. The method of claim 20, further comprising the step of applying at least one substantially permanent coating layer to the surface of said pull tab prior to laser ablating said surface, whereby a portion of said at least one coating layer is also removed by laser ablation during said laser ablating step.