WO2000066315A1

WO2000066315A1 - Method for inscribing indicia on or in a workpiece

Info

Publication number: WO2000066315A1
Application number: PCT/US2000/011393
Authority: WO
Inventors: Woong K. Oii
Original assignee: Pacific Technology Corporation
Priority date: 1999-04-30
Filing date: 2000-04-28
Publication date: 2000-11-09
Also published as: AU4673100A

Abstract

A method for inscribing an inscription on or in a workpiece by using a laser generation system (100), an optical system (200), a laser beam steering system (300), a workpiece mounting system (400), a table system (500), a control system (600), and an exhaust system (700). An optical system (200) receives and collimates light from the laser generation system (100). In the optical system (200), a red light beam conjoins the invisible beam, the pair of light beams thereafter traveling parallel with each other, the red light permitting an operator to see the relationship between a workpiece and a laser aiming cross in a fiberscope (410) or CCTV for properly orienting the stone or jewelry for appropriately locating an inscription thereon. A laser beam steering system (300), consisting of an x-axis galvo mirror (305) and a y-axis galvo mirror, receives the concentrated beams and directs the conjoined laser beams through four adjustable field lenses onto the workpiece.

Description

METHOD AND APPARATUS FOR INSCRIBING_. INDICIA ON OR IN A WORKPIECE

BACKGROUND OF THE INVENTION 1. Field of the Invention:

The invention relates to laser ablating. More specifically, the invention relates to ablating a workpiece to inscribe an inscription thereon and/or therein. 2. Description of the Related Art:

It is the common the practice in manufacturing, distribution, wholesaling, and retailing of finished jewelry, jewelry with set stones, and loose stones to mark the stones or jewelry to identify and track the stones as required by federal law. Historically, jewelry has been marked to identify the maker to assure the consumer of the precious metal content in the jewelry. Jewelers have hand engraved jewelry with an engraving tool or stamped jewelry with a hand punch. In some cases, desired markings have been designed into a mold for casting identifiable castings. The maker's or assayer's mark also has been added on dies used to stamp or strike jewelry, medals and coins to identify the mint master responsible for the precious metal content.

With precious and semi-precious stones, although uncertain, the practice of marking stones, particularly precious stones like diamonds, began in at least the Fifteenth century when owners' names sometimes were engraved on the diamond, especially stones of great importance or value. Thus, marking stones and jewelry is a time-honored practice as old as the craft of jewelry making itself.

While the practice of marking stones has improved from hand inscribed to hand punched to machine punched, only the method or machine has changed. Stone markers remain interested in finding better and faster more permanent ways to mark stones and jewelry. The invention provides a better and faster more permanent way to mark stones and jewelry. Prior inventions for marking stones left permanent markings on or in the stone that can not be removed without severely damaging the stone. The invention provides for marking stones such that the markings may be removed, depending on various factors.

SUMMARY OF THE INVENTION

The invention provides a method for inscribing indicia on or within a workpiece including directing a laser beam onto the workpiece by at least one mirror controlled by a computer or computer operator.

This invention pertains to the handling and marking of precious and semi-precious stones as is or prior to or following assembly with jewelry. The marking or inscription may be inscribed on or under the surface, within the body, of a stone without color, in black, or in color. The markings, for the most part, are intended to be visible in one form or another.

The invention provides a method for placing indicia on the surface and within the body of a stone and/or jewelry to prevent confusion during the manufacturing and distribution of the jewelry, and to prevent fraud during the sales and repairs thereto. The invention provides for marking a stone in a pleasing and decorative manner to enhance interest in an otherwise uninteresting stone, or a stone of little value, by covering all or part of the stone with colored or uncolored artistic detail or designs. The invention provides for marking a stone, or jewelry retaining a stone, with a minimum of effort and without effecting the value of the stone following marking. The invention also provides for removing stone markings without perceptibly reducing the weight. The invention provides improved elements and arrangements thereof, for the purposes described, which are inexpensive, dependable and effective in accomplishing intended purposes of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail below with reference to the following figures, throughout which similar reference characters denote corresponding features consistently, wherein: Fig. 1 is a schematic view of an embodiment of an apparatus for inscribing indicia on a workpiece constructed according to principles of the invention;

Fig. 2 is a schematic view of an embodiment of the visible diode laser system of Fig. 1;

Fig. 3 is a schematic view of an embodiment of the laser beam positioning system of Fig. 1 , including a motorized x-axis galvo mirror and a motorized y-axis galvo mirror;

Fig. 4 is a schematic view of another embodiment of the workpiece positioning system of Fig. 1;

Fig. 5 is a schematic view of another embodiment of an apparatus for inscribing indicia on a workpiece constructed according to principles of the invention; and Fig. 6 is a schematic view of an embodiment of an apparatus for simultaneously marking a target stone and jewelry with the same indicia.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention pertains to making semi-permanent and permanent marks on or under the surface of a precious or semiprecious stone, and on the surface of jewelry. The marks may assume the form of alphanumeric names, trademarks, logos, symbols, designs, serial numbers or letters, karat numbers or abbreviations, ring or stone weights, metal composition, words or phrases, style numbers, or any combination thereof. The markings fall into two basic categories, identification or security, for use in manufacturing and commerce, or decoration, to improve salability or merchantability.

In accordance with the principles of the invention, the above and other objectives are realized in practice when placing indicia on the surface or within a stone, or on the surface of jewelry carrying the stone with a beam of laser light. The markings on or in the stone range from imperceptible to obvious, depending upon the discretion of the operator. Identification or security markings may be inscribed deliberately so as to be impossible to see with the unaided eye or clearly visible. Decorative markings on or inside of a stone may be inscribed such that the inscriptions are clearly visible to the unaided eye and can not be altered or removed without causing severe damage to the stone. While extant markings on the surface of a stone are difficult to modify, the markings may be removed entirely with little effort by a trained operator or stone polisher without re-cutting, causing no loss of value or any perceptible loss of the size of the stone. Stones marked under the surface, within the body of the stone, are permanent. The markings on jewelry also range from imperceptible to obvious, depending upon the discretion of the operator. Generally, jewelry markings are to be easily read by the unaided eye. Removal or alteration of jewelry markings depends on the location and depth of the marking, the characteristics of the metal from which the jewelry is crafted and the skill of the operator.

Markings on a stone surface may be highlighted with a water-soluble black or colored ink that is exposed to a laser beam. Exposing the stone and the ink simultaneously to the laser beam creates a chemical reaction on the surface of the stone that bonds the ink permanently onto the stone without changing the color of the ink. Following bonding, washing the stone with water removes from the stone surface ink not exposed to the laser beam, leaving the highlighted indicia visible to the unaided eye. Highlighting the indicia also may be accomplished by covering the surface of the stone with a precious metal foil which is affixed to the surface of the stone. The stone and foil are simultaneously exposed to the laser beam, causing a chemical reaction on the surface of the stone that bonds the metal exposed to the laser beam to the stone. Washing the stone with water or a solvent, depending on the metal of the foil, removes from the stone surface foil not exposed to the laser beam, leaving visible only the highlighted bonded-metal indicia on the surface of the stone.

The same process may be used to replicate a black-and-white or color photographic image to the surface of the stone. With respect to a black-and-white photographic image, the process is the same as for generating black-ink indicia, as explained above. For color photographic images, a CPU breaks down the color photograph into primary colors. Similar to a color computer printer or color offset printer, which create full color images from the three primary colors, colored inks are applied and processed in three stages, in the same manner the black-ink image processing explained above. Referring to Fig. 1, to inscribe a workpiece, the invention includes a laser generation system 100, an optical system 200, a laser beam steering system 300, a workpiece mounting system 400, a table system 500, a control system 600 and an exhaust system 700.

The laser generation system 100 includes a laser head 105 that employs any one of the following types of lasers: Helium Neon Laser, Argon Krypton Ion Laser, Carbon Dioxide Lacer,

Hydrogen-Fluoride Laser or other Rare Gas Halide Excimer Lasers, Helium-Cadmium Laser, Copper Napor Laser, eodymium Lasers using any of the various host material crystals or gases, such as Yttrium- Aluminum-Garnet, Ruby Lasers, such as Chromium- Aluminum Crystal Lasers, Color Center Lasers, Semiconductor or Diode Lasers using electronically configured Aluminum, Indium or Phosphorous, Liquid Dye Lasers, or Free-Electron Lasers. The laser head 105 emits a laser beam from a laser cavity 110 which is directed to a Q-switch 115. Emitted light continues through the switch 115 and is reflected off of a rear mirror 120. At all times, the beam is highly directional, that is, all of the rays are nearly parallel with each other, as compared with a non-collimated light beam, which expands five or more times its original size within a short distance.

The laser beam reflected off the rear mirror 120 travels through a first set of aperture lenses 125, which concentrate the beam. The concentrated light is emitted through an optical safety shutter 130 when same is opened.

Because some laser production systems can generate elevated temperatures that may pose a danger to operating personnel or impact the system, the invention provides a water cooler 135 for cooling a laser head of such system. The water cooler 135 is connected to and controls a water cart 140 for delivering coolant to and receiving coolant from the laser head 105.

Referring also to Fig. 2, the optical system 200 receives light from the optical safety shutter 130 through a second upcollimator lense group 205 and travels through a first upcollimator lense group 210. Light from the first upcollimator lense group 210 reflects off of a first folding mirror 215 connected to a power monitor 220. The power monitor 220 controls or restricts amplifier and damage thresholds when the laser beam arrives at the first folding mirror 215, but before the laser beam strikes the second folding mirror 225. At the second folding mirror 225, red light produced by a visible laser diode 230 conjoins the invisible laser beam, the pair of light beams thereafter traveling parallel with each other. The white laser light is reflected from and the red laser light passes through the second folding mirror 225. The visible laser diode 230 renders the beam visible to permit an operator to see the relationship between a workpiece and a laser aiming cross in a fiberscope or CCTV for properly orienting the stone or jewelry for appropriately locating an inscription thereon. The conjoined beams enter an optical beam expander 235, which expands the beam prior to entry into a second aperture lens group 240 where the beam is concentrated.

Referring to Figs. 1 and 3, the laser beam steering system 300 receives the concentrated beams from the second aperture lens group 240 with an x-axis galvo mechanical mirror 305. The x-axis galvo mechanical mirror 305 reflects the light onto a y-axis galvo mechanical mirror 310. The x-axis galvo mechanical mirror 305 and the y-axis galvo mechanical mirror 310, positioned according to a first CPU 605, described below, directs the conjoined laser beams through four adjustable field lenses 317, which direct the beams onto the workpiece 800. The workpiece mounting system 400 may include any conventional fixture for receiving and maintaining a workpiece 800 for inscription.

The table system 500 includes a table 505 on which is mounted one or more mounting systems 400. A table motor 510 translates or positions the table 505 between a position at which a mounting system 400 may receive a workpiece 800, a position out of range of the laser beam, and a position within range of the laser beam where the workpiece 800 may be inscribed.

The control system 600 employs two CPUs 605 and 610, each for controlling separate functions. The first CPU 605 receives input from a keyboard 615 and displays output with a monitor 620. The first CPU 605 is connected to a hard drive back-up system (not shown) for storing all data in the event the CPU fails. The back-up system also provides a hard copy of the data for security in controlling the use of registered trademarks and the like, particularly when attached to serial numbers, which eliminates unauthorized use of the machines, or unauthorized access to data within the machines, as the hard drive is off premises. Referring also to Figs. 2 and 5, the first CPU 605 also is connected to the table motor 510 for positioning the table 505, an auto-focus device for a fiberscope 410, the power monitor 220, visible laser diode 230 and the water cooler 135. The first CPU 605 also controls a motor 315 for positioning the mechanical mirrors 305 and 310, which control the ultimate destination of the laser beam, including the depth, direction left to right and top to bottom, for generating an inscription.

The second CPU 610 also is connected to the fiberscope 410, with a steel gooseneck cable. The second CPU 610 controls the fiberscope 410 as well as a fiberscope light 415 for illuminating the workpiece 600 for the fiberscope 410. The fiberscope 410 provides for direct and oblique viewing of the workpiece 800 at up to

20-times magnification, at a working distance of 12.5 mm, with a field of view of 60 degrees, inside a radius of 1.75 inches. The fiberscope light 415 is a self contained fan-cooled quartz-halogen lamp. Proper illumination is very important when using the magnification system, which requires at least four times more illumination for each successive level of magnification for adequate resolution.

The auto-focus device includes infrared sensing technology and employs a 1.5 inch focal length lens.

The second CPU 610 also controls a CDC monitor 625, which allows an operator to observe, without requiring protective eye wear, the: (1) actual laser process; (2) placement of the target; and (3) functioning of the auto-focus device.

The second CPU 610 controls an optional exhaust fan motor 705 of the exhaust system 700 for collecting solid and gas waste, consisting of stone and metal byproducts from the laser process, that are caught in a filter and discarded. Although the waste gases and particulate matter are negligible, as the system is intended for large-scale, automated operation, over time, these wastes might build up. Thus, the invention provides for averting the deleterious effects of waste product buildup.

Referring to Fig. 4, another embodiment of the invention is adapted for high-production inscribing operations. To that end, the invention supplies another table system 1500 which includes a table 1505 for maintaining a plurality of workpiece mounting systems 400. A table motor (not shown) rotatingly indexes the table 1505. As an operator removes an inscribed workpiece from a workpiece mounting system 400, another operator may mount an un-inscribed workpiece which eventually is indexed into position for inscription. Referring to Fig. 5, a further embodiment of the invention provides for in-line viewing of the workpiece for more accurate positioning of the workpiece prior to inscribing. A fused silica mirror 1415 is positioned between the second aperture lens group 240 and the x-axis galvo mechanical mirror 305. As discussed above, the beam passing through the second aperture lens group 240 is conjoined white and red laser light. The conjoined light is reflected and/or passed through other mirrors and lenses prior to striking the workpiece 800. A portion of the conjoined beam reflects off of the workpiece 800 and is reflected and/or passes through the other mirrors and lenses again before reaching the mirror 1415. The mirror 1415 is coated on a front side 1420 with a light-absorbing coating that absorbs substantially all but light, for example, at 580λ, the 580λ light being reflected toward a CCTN 1425. The wavelength absorbed may be of any particular wavelength. The mirror 1415 allows the CCTN 1425 to operate much like a single lens reflex camera, allowing an operator to view precisely where the laser strikes the workpiece 800. Referring to Fig. 6, yet another embodiment of the invention provides for simultaneously inscribing a workpiece 1800, consisting of a stone 1805 and jewelry 1810, with the same inscription. This embodiment employs a beam splitter 1815 which splits the incident laser beam at an appropriate distance so that a portion of an inscribing laser beam strikes the stone 1805 and another portion of the laser beam strikes the jewelry 1810.

An alternative embodiment of the invention includes a benchtop viewing system, which offers easy stereo viewing of images with reduced operator strain, but at a much greater equipment cost. In operation, an operator uses the keyboard 615 to give directions to the first CPU 605, which are stored complete without a serial number, or complete with a serial number, or incomplete awaiting only the addition of the serial number from a bar code reader. Since the information is forwarded sequentially, the data is usually a trademark and a serial number, or a trademark or design alone, no further instructions are required unless the target stone or jewelry is out of position. Preferably, the operator typically removes a workpiece from a bar coded bag, inputs information encoded in the bar code with a bar code reader which sends the information to the CPU 605. The operator then feeds the stones or jewelry acquired from inventory control at one end of the table, allows the present inscribing system to mark the workpiece according to the instructions, then removes the finished marked workpiece at the other end and places same in the original bar coded plastic bag for transfer to bookkeeping.

At the conclusion of the engraving, the CPU turns the Q-Switch off, which in turn cuts off the white laser while leaving on the red laser for targeting, the table turns, a new target moves into position, and the entire process starts all over again.

Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.

Claims

I CLAIM:

1. A method for inscribing indicia on or within a workpiece comprising the step of directing a laser beam onto the workpiece by at least one mirror controlled by a computer or computer operator.

2. The method of claim 1, wherein the indicia is inscribed within the workpiece.

3. The method of claim 1, wherein the indicia can be removed without damaging the workpiece, causing the workpiece to lose value or requiring that the workpiece to be recut after removal of the indicia.

4. The method of claim 1, wherein indicia is imperceptible, obvious or combinations thereof.

5. The method of claim 1, further comprising the step of exhausting waste products produced by said inscribing.

6. The method of claim 1, further comprising the step of moving the workpiece, a jig maintaining the workpiece, the laser beam or combinations thereof.

7. The method of claim 6, wherein said step of moving the laser beam includes moving an x-axis mechanical mirror, a y-axis mechanical mirror or combinations thereof.

8. The method of claim 1, wherein said method is carried out without using an energy absorbing material.

9. The method of claim 1, wherein the indicia are inscribed simultaneously on a stone and on a piece of jewelry.

10. The method of claim 1, wherein the workpiece is in a natural state or an unfinished shaped state during said inscribing, the indicia being on or below the surface of the workpiece following finishing or polishing.

11. The method of claim 1, wherein the indicia is highlighted with black ink, colored ink, metal foil or combinations thereof.

12. The method of claim 1, wherein the indicia is permanently engraved, chemically bonded or combinations thereof.

13. The method of claim 1, wherein the indicia replicate black-and-white or color photographs.

14. The method of claim 1, further comprising positioning the indicia with respect to the workpiece with a fiberscope or CCTN that receives a reflected light from the workpiece that is coaxial with a path for a laser beam for carrying out said inscribing.