MXPA97006502A - A system and method for processing surfaces through a lá - Google Patents

Abstract

The present invention relates to an apparatus that simulates sandblasting treatment, comprising: a laser, a marking surface of material, having a surface adapted in operation to hold a material to be marked, a driving element, which operates to guide an output of said laser on said material according to an applied command, and a controller, which stores probability information for at least a plurality of areas in the material to be marked, said probability information indicating a pattern of sandblasting by applied to said material, and including information indicating a probability that said position is marked with the laser to simulate said sandblasting pattern, and said controller ordering said driving element and said laser to operate in accordance with said probability for produce greater laser output in areas of higher probability than in areas of lower probability to produce said pattern of sandblasting in said material.

Description

A SYSTEM AND METHOD FOR PROCESSING SURFACES MEPIAUTfi A FRÁSER The invention relates to a surface treatment with a laser, and more specifically to a system and method for processing surfaces made of a variety of materials with at least one laser beam. Background of the Invention A laser beam can interact with a surface in various ways to change surface properties, including light absorption, photon scattering and photon impact. For example, a surface can be burned by an intense laser beam. Some surface particles can be removed from a surface by the impact of a laser beam. Therefore, a surface can be treated with one or more appropriate lasers to achieve certain effects that can not be easily accomplished with other methods. An example is described in the United States patent application entitled Laser Method of Scribing Graphics, which is a continuation in part of the United States patent application Serial No. 08 / 550,339, filed on October 30 of 1995. Disclosure of the application entitled Laser Method of Scribing Graphics is incorporated herein by reference. This application describes the use of lasers to form graphs on various materials controlling the energy density per unit of time. The graphics can be patterns, images, letters and / or any other visual marks. Although other traditional methods have been used, such as pigmentation, printing, weaving, highlighting and stamping, laser methods seem to have certain advantages to produce complex and intricate graphics on materials. This is at least in part because many of the traditional methods lack the registration and precision necessary to ensure that the small details of the graphics are presented accurately and repeatable on the materials. In addition, laser methods obviate many problems associated with traditional methods such as the high cost of manufacturing equipment, equipment maintenance and operation, as well as environmental problems. A detailed description of laser methods for detailing graphics is disclosed by the inventors in the aforementioned United States patent application entitled Laser Method of Scribing Graphics. The measurement of the interaction of the laser with a material can be characterized by several parameters, including dot size, intensity, energy, etc. The inventors found that the preferred parameter is the energy density per unit time (EDPUT), defined as: EDPUT = laser energy area of the beam point projection speed where the projection speed is the speed at which the point of the scanning beam moves on a treated surface. The laser operating parameters, ie laser energy, beam spot size, and scanning speed, must be adjusted to achieve an optimum EDPUT for a specific material and a particular printing requirement. If the EDPUT is too high, the surface may be charred, burned or melted; if the EDPUT is too low, the effect of the laser treatment may not be sufficiently visible. The inventors recognized that lasers can also be used to treat the surface of a material in order to achieve a certain texture or appearance of the surface. Many materials used by the fabric industry are treated for this purpose. Denim fabrics can undergo a sandblasting process to obtain a worn look. Denim pants are often sold with a worn appearance on the upper portions of the knee and the back seat portion. The effect is similar to a feathered or shaded appearance in which the degree of worn appearance changes continuously along the length and width of the apparently worn areas.

A sandblasting treatment conventionally subjects the jeans to abrasion with sand particles, metal particles or other materials in selected areas, to impart a worn appearance with a desired degree of wear. This process sends a jet of sand particles from a sandblasting device to a pair of jeans. The random spatial distribution of the sand creates a unique appearance in a treated area. Jeans and other clothing treated with such a sandblasting process have been very popular in the consumer market. However, the sandblasting process has several problems and limitations. For example, the process of applying jets of sand or other abrasive particles presents considerable environmental problems. A worker usually needs to wear protective equipment and masks to reduce the impact of inhaling any particles of sand or other abrasive particles that are used in the air. The actual sandblasting process typically occurs in an enclosure that is shielded from the other areas in a manufacturing facility. Additional environmental problems arise with the cleaning and disposal of the sand. In practice, undesirable sand is rarely completely removed from the pockets of jeans or denim jackets. The sandblasting process is an abrasive process, which causes wear to the sandblasting equipment. Typically, the actual equipment needs to be replaced as frequently as after a year of normal operation. This may result in additional capital and installation costs. In addition, the actual cost of the sandblasting process is estimated as high as several dollars per unit of garment, depending on the utilization of the installed capacity. This high cost is at least partly due to the labor involved, the cost of the continued acquisition or repair of the equipment, the environmental cleanup required, the sand used, and the actual performance of the products. Furthermore, the sandblasting process can adversely affect the strength and durability of the finished articles, due to the abrasion of the sand or other particles that are used. Despite the above problems and limitations, the sandblasting process is still in wide use because there is no other alternative technique that can economically produce the desired surface appearance of the sandblasting treatment. In view of the foregoing, the inventors found it desirable to replace the sandblasting process with a new, environmentally friendly process that is capable of producing a sandblasting appearance, while reducing costs and maintaining the durability of the finished articles. In recognition of the above, the inventors invented methods of laser strokes to achieve a worn appearance on fabrics such as denim, the details of which are disclosed in the United States patent application entitled Laser Method of Scribing Graphics, incorporated hereinbefore. . For example, one method is to wrap the denim over a cone, cup or wedge surface that is placed in relation to a laser with a beam scanning device so that the focused beam projects different spot sizes at different locations on the surfaces due to a variation of distance from the focusing distance. In this way, the intensity of the beam changes with the location of the beam on the surface. Consequently, the degree of strokes with laser or EDPUT changes on a piece of cloth on the surface. The laser sweeps over the surface to treat a predetermined pattern such as a solid pattern or a pattern with closely spaced lines. The locations on the surface that are closest to the laser focus distance receive the highest beam intensity or EDPUT and therefore have the most worn appearance. In conversation form, the locations on the surface that are further away from the focus distance experience the lower intensity of the beam or EDPUT and therefore have the least worn appearance. This technique has the effect of continuously changing the focus of the laser by tracing the laser beam a pattern on the material. Alternatively, the focus of the laser can be changed with respect to a flat work surface to achieve the same effect. Another method previously disclosed by the inventors is based on the use of a reference EDPUT grid over a treated area. Again, a pattern is drawn on the treated area on a material surface. However, the operating parameters of the scanning laser are changed along the grid with a reference EDPUT distribution to achieve a desired effect, such as a feathered appearance. A third method uses a pattern that has a series of lines that continually increase or decrease line spacing and thickness to achieve a feathered or worn look. Alternatively, a radial gradient pattern may also be created by the scanning laser with predetermined EDPUTs to produce a desired fabric appearance. The results of the previous laser strokes techniques produced a feathered appearance that approximates the worn appearance achieved from the sandblasting process. However, the treated fabric does not exactly replicate the well-recognized worn appearance produced by the sandblasting process. This is at least in part due to the fact that the laser strokes techniques are based essentially on strokes with a regular pattern instead of the spatially random spots of sand with sand blasting or other abrasive particles. Also, previous laser methods usually have long processing cycle times. For example, a typical cycle time of 6 minutes or more is necessary to process an oval section of 21 inches in length. Another limitation is that laser strokes require a certain pattern with certain laser operating parameters (eg, EDPUT) for a particular fabric in order to create a worn appearance. As this can change from one fabric to another, the methods are very specific to the materials and are not universally applicable to different fabrics. SUMMARY OF THE INVENTION The present invention uses a laser surface processing system to simulate the worn appearance on a cloth surface produced by a sandblasting process in an economical manner. This is achieved, at least in part, by forming a random computer simulation of the appearance of a sand-blasting web and using a laser beam to mark the material in the shape of the sandblasted web. According to an embodiment of the invention, the laser surface processing system comprises: a laser system that produces a laser beam of a predetermined amount of output energy range that moves on a surface of a laser. material to mark a pattern defined by the user on it in response to a command applied; a controller having a microprocessor and communicating with said laser system for generating said applied command according to a respective laser impact frequency information indicative of said user defined pattern. The laser system may include a laser energy control capable of controlling the laser output level and turning the output beam on and off, a beam scanning and steering device, focusing optics, and a control computer. The control computer can be programmed to generate a laser frequency impact matrix based on the desired appearance of the surface. A random arrangement of numbers indicating the amount of laser treatment is used to simulate the random appearance in the spatial distribution of the abrasive particles in the sandblasting process. One aspect of the invention is the ability to control a feathers effect on the edges of the worn appearance of fabrics by adjusting a rate at which the distribution of probabilities in the impact frequency matrix changes with the positions. Yet another aspect is to process a selected area of the fabric with multiple laser scans based on a predetermined probability distribution of the desired appearance of a surface. A further aspect of the invention is the ability to exhibit the appearance of the surface and the modification by the user of the laser impact frequency information prior to actual processing. This is achieved by changing parameters of a pattern density matrix, a probability density matrix or an impact frequency matrix that determines the laser control codes. One implementation uses a user control interface having a user input device and a screen in the laser surface processing system. BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects and advantages of the present invention will become more apparent in the light of the following detailed description, as illustrated in the accompanying drawings, in which: Figure 1 is a block diagram showing a laser processing system for treating a surface of a workpiece according to an embodiment of the invention. Figure 2 shows an exemplary embodiment of the system of Figure 1, with two galvo-mirrors for scanning the laser beam on the surface of a workpiece. Figure 3 is a flow chart showing an exemplary method in accordance with this invention. Figure 4 shows an exemplary elliptical pattern with a worn appearance on a garment. Figure 5A is an elliptical pattern processed by laser, computer generated, with a single scan, according to the invention. Figure 5B is a computer-generated laser-elliptical pattern, using the same impact frequency matrix as in Figure 5A, with two laser scans, according to the invention. Figures 6A and 6B show computer simulated elliptical patterns with the impact frequency matrix of different shifting rates according to the invention. Figure 7A shows a spent, computer-simulated, laser processed pattern for denim trousers. Figure 7B is a density matrix indicating the right-hand portion of the spent pattern of Figure 7A. Figure 8A shows another computer-simulated spent laser processed pattern for denim trousers. Figure 8B is a density matrix indicating the right-hand portion of the spent pattern of Figure 8A. Figures 9A-9D are diagrams showing different exemplary laser scanning traces according to the invention. Figures 10A-10C are diagrams illustrating three examples of the laser processing system for a garment production line. The Figure 11 shows a laser processing system with a rotating garment carousel and multiple lasers. Figure 12 is a block diagram showing additional components of the control computer. Figure 13 is a flowchart for an exemplary mode operation using an initial pattern density matrix. Fig. 14 is a flow chart showing a user interface process based on Fig. 13. Fig. 15 is a block diagram showing a graphical user interface based on Fig. 13. Fig. 16 is a diagram of flow for an exemplary mode operation using an initial probability density matrix. Fig. 17 is a flow diagram showing a user interface process based on Fig. 16. Fig. 18 is a flow chart showing a graphical user interface based on Fig. 16. Detailed Description of the Invention The figure 1 shows a block diagram of a laser processing system for treating a surface. The solid lines with an arrow represent laser beams and the dotted lines represent electrical control signals. A laser 110 of any type, including but not limited to a gas laser and a solid state laser in continuous wave operation mode. { CW) or pulsed, produces a laser beam 114. A C02 laser may be preferred to process many materials.

The beam output power 114 is controlled by a laser energy control unit 112. A beam direction and scanning device 120 is positioned relative to the laser 110 and is operable to guide the laser beam anywhere in the a work piece surface supported by a support stage 140. The focus optics 130 is located at a desired distance from the support stage 140 relative to the beam scanning and direction device 120. A control computer 150 is used for controlling the operation of the laser 110, including the output power, the direction and scanning of the laser beam, and the spot size of the beam in the support stage, by changing the distance between the focus optics 130 and the support stage 140. Control of the output energy of the laser 110 includes turning on / off the laser beam, changing the output level, or other controls. Such control can be done either by directly controlling the laser itself or by modulating the output beam with an electrically excited beam shutter and a beam attenuator. Many aspects of these components are described in the aforementioned pending application entitled Laser Method of Scribing Graphics, but these can alternatively be controlled using the techniques described in U.S. Patent No. 5,567,207, issued to Lockman et al., Method for Marking. and Fading Textiles wi th Lasers, which is incorporated herein by reference.

The beam scanning and steering device 120 can direct the beam to any desired location in the support stage 140 or scan the beam on the support stage with a certain spatial sequence at a desired speed. In this way, the system 100 in general can be used to draw a pattern on a surface and treat a surface to achieve a certain appearance or achieve a combination of both. A parameter for measuring the degree of interaction of the laser with a surface is the energy density per unit time (EDPUT), as previously defined, and as described in the aforementioned United States patent application entitled Laser Method of Scribing Graphics. The EDPUT in the support stage can be determined by at least one of the following: the laser energy control 112, the direction and beam scanning device 120 for the beam projection speed in the support stage 140, or the focus optics 130, which changes the spot size of the beam. Therefore, a desired distribution of EDPUT with a certain spatial profile can be achieved. This results in either drawing a graph on a piece of work or producing a certain surface appearance. The computer 150 may have a plurality of programs for controlling the system 100 to achieve these functions, which will be described in detail. A variety of materials can be processed with the system 100, including but not limited to fabrics, furs, vinyl, rubber, wood, metals, plastics, ceramics, glass and other materials. These materials can be used to make different items. Some common examples include clothing, blankets, footwear, belts, bags and purses, luggage, vehicle interiors, furniture covers, and wall coverings. Figure 2 shows an exemplary implementation 200 of system 100. A laser 210, which may be one of several lasers, including C02 laser or YAG laser, produces different power outputs. An electrically controlled beam shutter (not shown) is included in the laser 210 to turn the laser on and off as desired. A CW C02 laser, Stylus, manufactured by Excel / Laser Control (Orlando, Florida, United States), can be used as a laser 210. The laser 210 generates a laser beam 214 in the direction of a beam direction and scanning device, controlled computer, having a first mirror 222 and a second mirror 226. The mirror 226 is mounted on a first galvanometer 220 so that the mirror 226 can be rotated to move the beam on an x axis in the support stage 140. A second Galvanometer 224 is used to control the mirror 226 so that the mirror 226 can move the beam in the support stage 140 along an y-axis., the galvo-mirrors 222 and 226 can be controlled to scan the laser beam in the support stage to generate almost any trace and geometrical shape that is desired. A galvanometer driver 260 receives commands, including numerical control commands from the computer 150, and controls respectively the movement of each galvo-mirror. The laser beam 214 is first deflected by the x-axis mirror 222 and subsequently by the y-axis mirror 226 to direct the beam through a focusing lens 230. The lens 230 is preferably a focus-focusing lens assembly. flat field, multiple elements, which is able to optically maintain the point focused on a plane as the laser beam moves through the material. A movable step (not shown) can be used to maintain the lens 230 so that the distance between the lens 230 and the support stage 140 can be changed to alter the spot size of the beam. Alternatively, the support stage can be moved relative to the lens 230. The support stage 140 has a work surface which can be almost any substrate, including a table, or even a fluidized gas bed. A work piece is placed on the work surface. Usually, the laser beam is directed generally perpendicular to the surface of the support stage 140, but it may be desirable to guide the beam to the surface at a certain angle to achieve certain effects. For example, the angle of incidence may vary between about 45 and about 135 °. The computer 150 may include a designated computer such as a workstation (not shown) to facilitate the formation of the desired graphic or a control matrix. For example, a graphic can be scanned into the workstation and converted to the appropriate format. This can increase the processing speed. The computer 150 then controls the galvo-mirrors to impart the desired pattern to a material at the appropriate EDPUT. The system 200 may also include a gas tank 270 for injecting a gas such as an inert gas into the work zone on the support stage 140. The amount of gas can be controlled by the computer 150. This use of an inert gas It can reduce the tendency to complete carbonization, burning and / or melting. This technique can also produce new effects in graphics. In general, any gas can be used in the work zone to create a new effect. The gas tank 270 can also be used to inject a gaseous pigment to help place it in a work piece. The laser systems described above can be used to impart graphics and / or to produce a certain surface appearance on a surface of a variety of articles and products. In particular, the systems can be used to treat fabrics to have the worn appearance produced by the conventional sandblasting process. The present invention has several advantages over the conventional sandblasting process. For example, the total cost of system hardware and maintenance of the operation is lower. The dangers for health and the environmental problems of the sandblasting process are essentially eliminated. The present invention can better preserve the durability of the treated materials than the sandblasting process. The product yield of the system of the invention is greater than that of the sandblasting process due to the precision and repeatability of laser processing. Furthermore, the present invention can not only generate the appearance of sandblasting in a denim, but can also impart the appearance of sandblasting on khaki materials and other materials. Furthermore, the precision control of the laser beam allows the system of the invention to better control how a selected area will be treated while the sandblasting process it simply can not give much control to a user. Still another advantage of the invention is that the laser surface treatment with respect to a desired appearance can be easily combined with the drawing of complex and intricate graphics in the area treated with the same processing system without requiring additional devices. A first embodiment of the invention uses the computer 150 of the preferred system 100 of Figure 1 to produce a probability density matrix which in turn is used to create an impact frequency matrix. The impact frequency matrix is used to control the laser to produce a desired two-dimensional spatial profile or pattern. An area selected to be treated on a fabric or article of clothing is divided into a matrix of pixels. The impact frequency matrix indicates the number of times each individual pixel is struck by the laser beam. The computer 150 uses the impact frequency matrix to generate a set of control codes to control the laser energy control 112 and the beam scanning and direction device 120. The energy control 112 keeps the laser beam 114 active When scanning the beam places on a canvas that correspond to pixels with positive impact frequencies and turns off the laser beam when scanning the laser places with zero impact frequencies. In this way, the laser beam 114 is activated and iivated when scanning through a treated area of a desired geometric shape in a fabric. Multiple laser scans are needed at the places that are hit by the beam more than once. The areas of a fabric having places that are hit more frequently by the laser beam have a high degree of worn appearance. Conversely, areas that have places that are hit by the laser beam less frequently will have a lower degree of worn appearance. The final effect of the scan is equivalent to applying many laser beams simultaneously on the fabric with a random distribution similar to the application of sand particle jets. For this reason, this laser surface treatment can be referred to as a laser jet process, which is analogous to sandblasting. The probability density matrix assigns a density of probabilities to each pixel. This assignment of probabilities can be done mathematically for any number of rectangular geometric shapes, for example ellipses, rectangles, etc. Alternatively, the assignment of probabilities can be manually set and stored in a data file. In this way, a probability density matrix for a selected geometric pattern is predictable and defined. If the probability density matrix is used directly to generate control codes for the processing laser, the resulting pattern will have a predefinable and defined appearance or an artificial appearance. This can not produce the random aspects of a sandblasting pattern. The random aspect of the sandblasting pattern is preferably achieved by the impact frequency matrix. The impact frequency matrix is based on the probability density matrix in the sense that the spatial distribution of the probability density remains the same in the impact frequency matrix. However, the frequency of impact in each location is also determined by a random number produced by a generation of pseudo-random numbers with a computer (for example, the control computer 150 of FIG. 1). This aspect of the invention allows the impact frequency matrix to simulate the random aspects of a sandblasting pattern. The random numbers generated by computer are based on an initial seeding of random numbers. Using different initial sows of random numbers can result in different series of random numbers and thereby further increase the simulated random appearance. Many different patterns can be produced, each pattern having a different choice from the initial seeding of random numbers. Suppose for the moment that the value of the probability density lies between 0 and 1 for each pixel. This process establishes the possibility of an impact for that pixel equal to the density of probabilities. For example, if a pixel has a probability density of 0.6, it has a 60% chance of receiving a pact from the laser beam and a 40% chance of not receiving an impact. Probability densities greater than one are also contemplated. In general, the integer portion of the probability density for a pixel indicates the minimum value of the impact frequency for that pixel. For example, a probability density of 2.4 for a pixel indicates that the pixel has a 40% chance of receiving three hits by the laser beam and a 60% chance of receiving two hits. According to the invention, the prior art can be extended to allow multiple passes in the generation of the impact frequency matrix. In this extension, the impact frequency matrix is generated cumulatively by two or more applications of the process described above using the same or different probability density matrices. An advantage of this process is that it simulates the random nature of the impact of the abrasive particles that collide in the fabric in a sandblasting process. This contributes at least in part to the much improved appearance resulting from using the system of the invention on the effects by other previously described laser methods. Fig. 3 is a flow chart showing a process of producing a desired sandblast pattern on a cloth. First, in step 310, a real sample of a material treated with sandblasting is obtained. The surface appearance of the sample pattern is sampled in step 320, so that the exact places and frequency at which the sand particles stick are determined. Next, in step 330, a probability density matrix is generated based on the sampling results of step 320 and a generation of random numbers. The probability density matrix and the corresponding impact frequency matrix are generated based on pseudo-random numbers. The impact frequency matrix is subsequently used to control the laser beam in step 340 when treating a fabric to simulate the appearance of sandblasting. The mathematical approach to establishing the values of the probability density matrix can be illustrated by an elliptical pattern, as shown in Figure 4. This is an effective way to create an oval-shaped wear pattern around the portion of the knee of a pair of denim jeans. An elliptical area 420 can be used for simplicity. In general, any geometric shape can be used. In this way, the desired replication of a sandblasting pattern is one in which the frequency of being hit by a laser beam is greater in the center of the ellipse 320 and decreases in a continuous but random manner when moves away from the center towards the extreme limits. This is produced by a probability density matrix that has the value of the high probability at the center of the ellipse and values that continuously decrease in a predetermined way when moving towards the extreme limits. The method of producing such a probability density matrix begins with the assignment of the X and Y dimensions of the ellipse, as indicated in Figure 4, the probability density at the center O of the ellipse 420 being represented by a and the density of probabilities in the limit being represented by b, which is set to be a constant at any point in the limit in this example. Then, the probability density of a pixel, as indicated by point D, can be determined by the ratio, R, of the distance from the center of the ellipse 0 to D with the distance from the center 0 to a point Db in the extreme limit at which the same vector as D intersects with the ellipse 420: R = 0D / 0Db The probability density for point D is then determined as follows: Probability density = a + Rp (ba) where the coefficient of the exponent, p, determines the shift or fade rate in the worn appearance. For example, for p >; 1, the shift can be considered fast; for p = 1, the shift is moderate; and for p < 1, the run is slow. Figure 5A shows a computer-generated laser jet pattern of an ellipse created by setting the density of probabilities at the center a = 0.9, the density of probabilities at the extreme limits b = 0.1, and the displacement coefficient p = 1 for a one-pass process Figure 5B shows a pattern with a, b and p set as in Figure 5A but using a two-pass process. Figures 6A and 6B show computer-generated laser jet patterns of an ellipse with a maximum probability density in the center of 3.2 and a probability density of 0 at the extreme limits. Figure 6A is generated by a shift coefficient p = 2 and Figure 6B is generated by a shift coefficient p = 0.5. The significance of the shift is clearly shown by the difference in the outer edge distributions. In this way, the bleed can be used to precisely control the feathered effect. According to the invention, more complex patterns can be formed by manually setting the values of the probability density matrix and storing them in a data file. Figure 7A shows a computer generated pattern having an upper portion 710 and a lower portion 720. The upper portion 710 can be used for the worn look in the leg portion of denim pants and the lower portion 720 can be used for the worn appearance in the area of the knees. This is one of the popular worn looks on many pants. Figure 7B shows the probability density matrix in a tabular form for the laser jet pattern of Figure 7A. The highest probability density is 2.0. Note that Figure 7B only shows the probability density matrix for the right hand portion of the laser jet pattern. The laser jet pattern of Figure 7A is symmetric about the line 7C-7C. Another laser jet pattern generated according to the invention is shown in Figure 8A. The probability density matrix for the right-hand portion is listed in a tabular form in Figure 8B. The spatial orientation of the pattern in the fabric can be adjusted by setting various laser operating parameters either by hardware or by software implementation. For example, the pixel density and the scan angle can be set in such a manner. According to a second embodiment, the impact frequency matrix can be implemented by keeping the laser beam in the places that have positive impact frequencies and adjusting the operating parameters to increase the EDPUT according to the impact frequency, that is to say, higher EDPUT values are given to places with higher impact frequencies. Referring to Figure 1, the EDPUT can be adjusted by changing combinations of the following: the power output level with the power control 112, the scanning speed by the beam scanning device 120, the relative distance between the lens of focus 130 and support stage 140. The EDPUT values used in this embodiment are preferably within a certain range for each material. If the received EDPUT exceeds a maximum range limit, the surface may be burned or charred. In converse form, the effect of the laser processing may become imperceptible if the received EDPUT is less than a minimum range limit. Therefore, one way to change the EDPUT based on the impact frequency matrix is to correlate the EDPUT of the laser system with the impact frequency in a linear or non-linear relationship. The EDPUT value of the laser beam can be set to the maximum value in the permitted EDPUT range for that material for the areas assigned with the highest impact frequencies and to the minimum EDPUT value for assigned areas with the lowest impact frequencies. For example, if the center of the ellipse 420 has a probability of 1 assigned by the probability matrix, the corresponding impact frequency matrix can be used to the EDPUT value of the laser beam in the center to the maximum EDPUT in the allowed range of EDPUT for that material. At the extreme limit of the ellipse 420, the probability is 0 and therefore the minimum EDPUT value is assigned according to the corresponding impact frequency matrix. Other ways of correlating the impact frequency matrix and the EDPUT values of the laser system may also be used in accordance with the invention. The test results demonstrated the possibility of simulating almost exactly the worn appearance achieved from the sandblasting process. The results were particularly promising because, to the best of the knowledge of the inventors, there had never before been a process that could achieve such a distinct appearance from the sandblasting process. One aspect of the impact frequency matrix according to the invention is its scalability. An impact frequency matrix of a pattern can be scaled with the dimension of the pattern. This scaling technique can be used to reduce the processing cycle time of a large pattern. For example, the cycle time to process a typical 21-inch oval section from upper hip to below knee in a pair of jeans was around 6 minutes for a set of operating parameters. However, the cycle time can be reduced by the following scaling process. First, an impact frequency matrix is generated for a pattern proportionally smaller than the desired size by a predetermined factor (for example, a factor of 2). This is configured in a scanning control program in the control computer 150 of the system 100 of FIG. 1. For a given actual density of scan lines, the processing cycle time of the smaller section is shorter than that of the largest section desired with the same pattern. Secondly, the scan control program is set to change a size command to increase the size of the image to the desired size that has been reduced in the first step. This size command can include a height command to change the height. For example, if the pattern size used in the first step was 1/2 of the original size, then the height command in the laser file would be set to 2, that is twice. This effectively scales an impact frequency matrix for the smaller section to process a larger section of the same pattern. The size command is converted as laser control codes that control a laser processing beam to move at a prescribed distance in a workpiece according to positions of the array elements in the impact frequency matrix. Next, the EDPUT is adjusted (for example, incremented) so that a high-speed scan reading can be used to further reduce the cycle time for the desired finishing quality. The effect of the prior scaling technique is to cause the laser to traverse the section of the pattern in the same number of scanning passes as in the case of a pattern of a smaller size (for example, half), while still being they keep the laser scans relatively consistent. An optional step of adjusting the size of the beam point can be carried out after the re-sizing step of the scanning control program, in which the spot size of the laser beam 114 is increased to a predetermined diameter by adjusting the Relative distance between focus optics 130 and support stage 140. The magnitude of the increase in beam size usually has a relationship with the size reduction factor used in the first step. For denim and some other fabrics, this optional step may not be necessary due to the fabric's tolerance of the denim. A significant reduction in the processing cycle time can be achieved by optimizing the operating parameters, including but not limited to the scaling factor, the magnitude of the increase in beam size, the laser scanning speed, and the laser power. . When processing a 21-inch oval, for example, the processing cycle time can be reduced six times from around 6 to about 1 minute with a scaling factor of 2. Another aspect of the impact frequency matrix technique is that the impact frequency matrix can be easily configured to generate a variety of different surface appearances, including different degrees of wear on the worn appearance of sandblasting. For example, an impact frequency matrix can be generated to produce a variety of pixelated appearances and appearances as if pellet shot or other means were applied to the fabric. This can be achieved merely by changing the densities of probabilities within the limits of a desired pattern. For example, the densities of probabilities in the center and the limits of the previously described elliptical pattern of Figure 4 can be changed for different appearances. In addition, various graphics can be superimposed on a section treated with a laser jet using the same laser system. A graphic can be drawn on a selected area of a fabric first and then the laser jet process is carried out to achieve a desired worn effect on the plotted graphic. Few surface processing techniques, including the sandblasting process and laser techniques previously described, are capable of providing the flexibility, diversity, and precise control of the preferred die technique of the present invention. In accordance with the invention, multiple laser scanning passes are carried out by treating a selected section of a surface. In general, any beam scanning scheme according to the invention can be used. For example, a commonly used line scan scheme can be used to scan a surface in the form of line by line, each scan line being a substantially straight line. Figures 9A and 9B show two examples of exploration in straight lines. The inventors discovered that non-straight scan lines can also be used to achieve certain surface appearances that are not possible with straight scan lines. In particular, scanning in non-straight lines can be used to improve the feathered effect on a fabric. Referring to Figure 1, the beam scanning and directioning device 120 and / or the focusing optics 130 can be controlled with the control computer 150 so that the trace of the scanning beam on a surface forms a certain pattern of waveform. Figure 9C shows a sinusoidal or cosineidal type scan line. Figure 9D shows oscillating scan lines. Two oscillating scan lines may or may not overlap each other. Oscillating scanning lines can be used in the scaling technique to compensate for increased scanning spacing due to the increase in the size of an area to be processed. Figures 1 and 2 generally show laser processing systems for plotting graphics and treating surfaces in a workpiece. These systems can be used to process jeans or other clothing. Figures 10A-10C illustrate three examples of a laser processing system for denim trousers. A motorized carrier 1010 (e.g., an assembly line) provides an automated way to feed denim trousers one by one to a processing location where the laser system is located. Also included is a self-sizing member 1020 having automatic sizing sensors for detecting the actual size of the garment so that an appropriate location for imparting a worn graphic or appearance can be determined. In figure 10A, a beam of a single laser produced by a 1030 laser is used to process a section at a time. Multiple laser beams can be used to simultaneously process multiple sections in a pair of jeans to increase the processing speed of the system. For example, Figures 10B and 10C show that two lasers 1030 and 1040 are used to produce two beams to simultaneously process two different sections in a pair of pants. Lasers can be placed on the top of a table with a laser beam striking the fabric in approximately a vertical direction, or the lasers can be placed so that a laser beam hits the fabric approximately in a horizontal direction . Figure 11 shows another laser processing system according to the invention. A motorized rotating carousel 1110 is used so that pants wrapped around a shape can be automatically fed to a processing location. One or more laser beams can be used to simultaneously process one or more sections in a pair of pants. The example of Figure 11 shows that the front legs and the rear panels are being processed by indexing the rotating carousel 1110 the garment for further processing. Another aspect of the invention is that the laser processing process can be used either after the garments are sewn and washed, or before they are sewn and washed. Figure 12 further shows some components that can be included in the control computer 150 of Figure 1. A central processing unit (CPU) 151 is the computer engine 150, which includes a microprocessor. A memory unit 152 is used to store data and instructions. For example, the data may include the geometric shape of a pattern, a pattern density matrix, the probability density matrix, the impact frequency matrix, and the laser control codes. The instructions may include software packages to, for example, generate the pseudo-random numbers, produce the probability density and impact frequency matrices, control the screen content, manage data, and control various components in the processing system of laser. A user input device 153 receives and transmits a user's instructions or captured data to the CPU 151. A cursor pointing device (e.g., a mouse), a computer keyboard, or a touch screen input device, it can be used alone or in combination to serve as a user input device 153. A screen 154 can be any device capable of displaying text and graphics, such as a CRT monitor, an LCD screen, or a video projection device. An input / output interface 155 indicates either an independent interface or a portion of an integrated interface that is connected to other components of the laser processing system. For example, Figure 1 shows that the laser power control 112, the beam scanning and directioning device 120, and the focusing optics 130 can be connected to and communicated with the CPU 151 through the interface 155. An interface of User control is implemented in the system. The interface includes the user input device 153 and the screen 154, which are supported by the CPU 151, the memory unit 152 and other components of the control computer 150. This aspect allows a user to simulate a jet pattern of sand produced with an impact frequency matrix by means of a graphic representation of the pattern on the screen 154. Such a visual representation of the pattern can be used to determine the appearance of a pattern or to compare the effects of different impact frequency matrices for the same geometric pattern, before actually marking the pattern on a surface by means of the laser. For example, the geometry of a pattern can be any form and can be generated conveniently and quickly by means of software at any time, according to the desire of a user. The characteristics of the probability density matrix, such as the creep coefficient for flaring effects and the maximum / minimum probability densities, can be changed during the simulation stage until a desired result is achieved. The initial sowing of random numbers can also be altered to obtain different random numbers by forming the impact frequency matrix. All these and other pattern manipulations can be performed through the user control interface of the control computer. The advantages of this aspect of the invention include flexibility, reduced cost and reduced design time. A processing process different from the process shown by the flow chart 300 can be implemented using the user control interface. One embodiment is shown in Figure 13. The initial geometry (e.g. shape and dimensions) and jet application density distribution are selected to form a pattern density matrix. Similar to the probability density matrix, each element in the pattern density matrix includes information on both geometric shape and density. Preferably, the pattern density matrix is small, for example limited to about a few hundred elements in each dimension. The form can be any form selected by the user or to satisfy a need in a specific application. In particular, any irregular pattern can be implemented in a pattern density matrix. The geometric aspects of a pattern represented by a pattern density matrix can be created in a systematic way using formulas or mathematical equations. This systematic approach can be advantageous in certain ways and can substantially eliminate the size limitation of a pattern density matrix, since the pattern matrix can be generated using a computer. However, for certain irregular patterns and particularly some unusual geometric geometric patterns, the implementation of the previous systematic method can be very time consuming, since complex mathematical calculations or derivations may be necessary to derive one or more formulas or equations to represent the irregularities of the shape. Thus, a small-sized pattern density matrix can be created manually by typing the desired matrix elements, for example by means of the computer keyboard, or by converting a graphic pattern in digital form into the desired matrix elements. The pattern density matrix can be edited at any time by the user. In addition, the pattern density matrix may be in numerical tabular form as a conventional matrix or in a graphic form. The pattern density matrix may be stored in the memory unit 152 for further processing. This completes step 1310. In step 1320, the scale factors are first determined for the expansion of the pattern density matrix to a density matrix of probabilities to a desired size.

A scale factor is sufficient if the scaling is carried out in only one direction. Two additional scaling factors may be necessary for more complex scaling operations in multiple directions. A linear interpolation can be implemented by forming a probability density matrix from a pattern density matrix in order to preserve the relative density distribution of the original pattern density matrix. This linear interpolation is two-dimensional, since it is carried out in the same plane. In many practical cases, a linear interpolation in each of two orthogonal directions may be desirable. Next, in step 1330, an initial seeding of random numbers is selected and the impact frequency matrix is formed by correlating the probability density matrix with the random numbers produced by a generation of pseudo-random numbers based on the seeding. In step 1340, a graphic representation of the impact frequency matrix is generated. This can be done using a graphic program. The graphic is shifted on the screen 154 to show the user what the appearance of a treated surface would be if the impact frequency matrix is actually used to process a surface with the laser processing system. If the user decides that the appearance is satisfactory, the impact matrix is then used to generate laser control codes for a subsequent surface treatment. However, if the user decides that the surface appearance is not satisfactory, the impact frequency matrix can be changed by adjusting at least one of the following: the pattern density matrix following the turn 1342, the probability density matrix following the turn 1344, or the initial seeding of random numbers following the turn 1346. The above process can be repeated many times until a desired graphic representation is achieved with the impact frequency matrix. Table 1 shows an example of a 5 x 5 pattern density matrix. The values of the elements of the matrix dictate both the distribution of densities and the geometric shape. In this example, the pattern density matrix of Table 1 shows a diamond-like shape and a maximum density value at the center and a density distribution that decreases from the center to the periphery. Table 1 Pattern Density Matrix A bi-dimensional linear interpolation can be carried out in the pattern density matrix shown in Table 1 to produce a respective probability density matrix. For example, two scaling factors, 2 and 3, can be selected for the x and y directions, respectively. In this way, the probability density matrix has 10 columns and 15 rows (that is, a 15 x 10 matrix). Table 2 shows the probability density matrix. Next, a 15 x 10 array of pseudo-random numbers produced from a selected seeding is used to correlate with the probability density matrix. This generates an impact frequency matrix, as shown in Table 3, for a one-pass process. For a two-pass process (ie, corresponding to a maximum density value of 2), the impact frequency matrix is shown in Table 4. The flow diagram 1300 reflects the execution steps of a software that controls the user control interface. This process can take a different form to the user in the user control interface in order to be friendly and convenient to the user. For example, steps 1320 and 1330 and those associated with feedback loops 1344 and 1346 may appear as a one-step process to produce the impact frequency matrix to the user. Therefore, an embodiment of the user interface flow may look like Figure 14.

Initially, a user is given the option of either retrieving a pattern density matrix pre-stored in the memory or entering a new one (step 1410). An option can be implemented to allow the user to look at the density matrix either in tabular mode or in graphic mode. In step 1420, a user captures all the parameters for the probability density matrix and the impact frequency matrix. The user then proceeds to generate the impact frequency matrix in step 1430. Subsequently, the graphic display of the impact matrix is displayed on the screen. At this point, the user can select one of the three options: move forward to generate the laser codes (step 1450), reset the screen parameters to generate a new impact frequency matrix (loop 1444), or use another pattern density matrix to re-start the process. Note that the underlying execution of step 1320 (generating the probability density matrix) in the actual software process is invisible to the user in the user interface. A graphical user interface on the screen (GUI) can be implemented based on the flow chart 1400. An example is shown in figure 15. For applications with geometric shapes that can be generated with formulas or mathematical equations, the steps related to A pattern density matrix can be eliminated since a probability density matrix can be easily created by the control computer. The elliptical patterns marked on the pants are examples of this type of applications. Figure 16 shows an embodiment of the control software for the user control interface. Figure 17 shows an embodiment of the user interface flowchart. Figure 18 shows an example of the GUI based on the flow chart of Figure 17. The user control interface described above can also be used when plotting patterns on a surface. In this way, a pattern can be displayed for inspection or for design purposes before actual processing. Although the present invention has been described in detail with reference to the preferred embodiment, a person skilled in the art to which this invention relates will appreciate that various modifications and improvements may be predictable. For example, the support stage 140 in the system 100 of Figure 1 can be movable by a motor controlled by the control computer 150 so that a fixed laser beam can be used to plot graphics or create a worn out appearance, since A cloth can be moved relative to the laser instead. For another example, the laser output beam 114 unique 110 can be divided into multiple beams and each of the multiple beams can be independently controlled with a set of steering and focusing devices. Therefore, the multiple beams of the single laser can be used to simultaneously process different sections of a garment. Further, two independently controlled scanning laser beams can be used simultaneously to process the same section of a garment, one drawing a graph and the other producing a desired worn appearance. This can also increase the performance of the system. Yet another variation of the preferred embodiment is the implementation of multiple pattern processing with a single execution of the control processes illustrated in Figures 3, 13, 14, 16 and 17. Two or more processing laser beams are controlled by the same impact frequency matrix to process two or more different areas in one or more pieces of work. For example, the same pattern can be created on both sides of a garment using position shifts and angular re-alignments by controlling one or two laser beams. If a single laser is used, the position and direction of the beam are changed from the processing of one area to the processing of another area with the same impact frequency matrix. In this way, two areas are processed sequentially. If two lasers are used, position shifts and angular re-alignments are used to control the lasers to point to different areas with possibly different directions. In this case, the two areas are processed simultaneously according to the same impact frequency matrix. These modifications and others are intended to be encompassed by the following claims.

Probability Density Motive (Scale Factor X = 2, Scale Factor Y = 3) TABLE 2 Impact Frequency Engine (One Step) TABLE 3 44-C Impact Frequency Drive (Double Pass) TABLE 4

Claims (35)

-45- CLAIMS

1. An apparatus that simulates sandblasting treatment, comprising: a laser; a marking surface of material adapted in operation to hold a material to be marked; a driving element, which operates to guide an output of said laser on said material according to an applied command; and a controller, which stores information indicative of a sandblasting treatment pattern by being applied to said material, and ordering said driving element and said laser to produce said sandblasting pattern in said material.

2. An apparatus as in claim 1, wherein said information includes information, for each position in the material, of a probability that said position is marked by the laser.

An apparatus as in claim 2, wherein said controller is operable to control an output energy level of said laser according to a randomly generated impact frequency based on said probability.

4. An apparatus as in claim 2, wherein said controller is operable to activate and deactivate an output laser beam from said laser according to a randomly-generated impact frequency -46 based on said probability.

An apparatus as in claim 2, wherein said driving element guides an output of said laser in said material with a plurality of scans according to said command to produce said sandblasting treatment pattern.

6. A method of simulating a sandblasting effect on a material to be marked, comprising: placing a material by marking on a support stage where said material will be marked by a controllable laser; determining a desired pattern of sandblasting treatment to be formed in said material, and determining information indicative of said sandblasting pattern to be formed in said material, said information indicating for each area of said material whether said controllable laser will mark or not in said material; and using said information to control said controllable laser to mark said material to simulate said sandblasting effect.

A method as in claim 6, wherein said step of determining information comprises sampling a sandblasted material and determining where changes occur to said material, and using said controllable laser to cause changes to said material.

8. A method as in claim 6, wherein said step of determining information comprises determining a matrix of spatial probability of change of said material, and controlling said controllable laser to change said material according to said probability matrix.

A method as in claim 8, wherein said probability matrix is a function of a distance of each area in said material from a reference point, and further comprising determining a distance in each area in said material from said reference point, determining a probability of a laser strike using said distance to obtain a value from said probability function, and controlling said laser controllable according to said probability.

A method as in claim 9, wherein said probability is a value indicating a number of times of striking by said laser beam, each integer value indicating a number of strokes of said laser beam, and a decimal value indicating a percentage blow value on occurrence of another pass of said laser beam.

11. A method as in claim 6, further comprising changing an operating resolution of said laser beam to change a time to mark said material.

12. A method as in claim 11, wherein changing said resolution includes: determining a location of a second desired sandblasting treatment pattern that is proportionally larger than said sandblasting pattern desired by a default dimension factor; and controlling said controllable laser according to a probability matrix indicative of said sand blasting effect for said desired sandblasting pattern and based on said predetermined dimension factor to mark said second desired pattern of treatment with sandblast.

A method as in claim 6, further comprising controlling said controllable laser so that a beam produced by said laser marks a wave-like trace on said material.

14. A laser processing system for processing a surface of a workpiece, comprising: a laser operable to produce a laser beam; a beam steering device arranged relative to said laser for receiving said laser beam and operable to direct and scan said laser beam in a predetermined manner; a support stage having a surface for retaining said work piece by being marked by said laser beam; and a control computer electrically connected to said laser and said beam steering device, said control computer being programmed to control said laser beam based on an impact frequency matrix that is indicative of a pattern to be imparted. to said piece of work.

A system as in claim 14, wherein said laser has a controllable output energy level, and said laser comprises a beam control element that operates to activate and deactivate said laser beam.

16. A system as in claim 14, further comprising focus optics relative to said beam direction device and spaced from said surface in said support stage at a predetermined distance, said focusing optics operable to focus said laser beam. .

17. A system as in claim 16, wherein said focusing optics and said support stage can be spatially adjusted relative to each other.

18. A system as in claim 14, wherein said impact frequency matrix has a positioning dependency with respect to a reference in said pattern.

19. A system as in claim 14, wherein said impact frequency matrix has a pseudo-random property that is attached to a probability distribution profile to simulate an effect of a sandblasting process.

A system as in claim 19, wherein said control computer is further operable to control said laser to plot graphics on said workpiece according to a graphics stroke command, said graphics stroke command and said impact frequency matrix being operable in a combination to control said laser beam.

21. An apparatus that simulates sandblasting, comprising: a laser system, which produces a laser beam that moves on a surface of a material to mark a pattern on said material according to an applied command; a controller connected to said laser system and configured to communicate with said laser system to generate said command applied in accordance with information indicative of said pattern, said information including a pseudo-random characteristic that simulates a jet treatment effect; sand; and a user control interface that includes a user input device and a screen, said user control interface connected to said controller and configured to produce a graphic representation of said pattern based on said information on said screen before processing in said material with said laser system and to allow modification of said laser impact frequency information.

22. An apparatus as in claim 21, wherein said information is in the form of a laser impact frequency matrix in which the values and positions of the elements of the matrix indicate the geometry and appearance of the laser. said pattern, and said impact frequency matrix is generated by a correlation of pseudo-random numbers with a probability density matrix indicative of the laser marking processing density within said geometry of said pattern.

23. An apparatus as in claim 22, wherein said modification of said laser impact frequency information is carried out by changing said probability density matrix.

24. An apparatus as in claim 22, wherein said modification of said laser impact frequency information is carried out by changing said pseudo-random numbers.

25. An apparatus as in claim 22, wherein said user control interface is configured to perform a graphical user interface represented on said screen, said graphical user interface including a representation window to represent graphics and texts and a window of commands that have a plurality of user control buttons.

26. An apparatus as in claim 25, wherein said user control buttons include a first button for receiving or creating said probability density matrix, a second control button for setting screen parameters for editing said matrixes of probability density and impact frequency, a third control button for executing a representation of a simulated pattern, a fourth control button for generating laser control codes, and a fifth control button for sending said laser control codes to said laser system.

27. An apparatus as in claim 23, wherein said probability density matrix is generated by means of a pattern density matrix by performing a linear interpolation using scaling parameters selected by the user.

28. An apparatus as in claim 27, wherein said controller comprises: means for determining said pattern density matrix indicative of said pattern; means for generating said probability density matrix in response to user parameters based on said pattern density matrix; means for generating said impact frequency matrix based on a random seeding number selected by the user to generate said pseudo-random numbers; means for producing a graphical representation of said pattern according to said impact frequency array in response to a user command; and means for generating said laser control codes using said impact frequency matrix.

29. An apparatus as in claim 22, wherein said controller includes: means for generating said probability density matrix in response to user parameters based on said initial pattern density matrix; means for generating said impact frequency matrix based on a random seeding number selected by the user to generate said pseudo-random numbers; means for producing a graphic representation of said user-defined pattern in accordance with said impact frequency array in response to a user command; and means for generating laser control codes using said impact frequency matrix.

30. A method of simulating a sandblasting treatment pattern using laser processing, comprising: forming a probability density matrix indicative of the geometry and appearance of a pattern; correlating a set of pseudo-random numbers with said probability density matrix to generate an impact frequency matrix; and -54- generating laser control codes based on said impact frequency matrix.

31. A method as in claim 30, further comprising: producing a graphic representation of said pattern according to said impact frequency matrix; and modifying said impact frequency matrix when said graphic representation deviates from the appearance of said pattern.

32. A method as in claim 31, wherein said modification is achieved by changing said pseudo-random numbers.

33. A method as in claim 31, wherein said modification is achieved by changing said probability density matrix.

34. A method as in claim 30, further comprising controlling a first laser to mark said pattern on a material using said laser control codes.

35. A method as in claim 34, further comprising simultaneously controlling a second laser with said laser control codes to mark said material at another location.