FIELD OF THE INVENTION

[0001]
The present invention relates generally to methods and apparatus for producing carved signs, and more particularly to methods and apparatus for producing carved signs using computers.
BACKGROUND OF THE INVENTION

[0002]
Carving, dating long before paper was invented, can be considered one of the earliest forms of writing. Letters carved in wood provide a sense of warmth and a feeling of permanence, and can focus the attention of viewers in a most dramatic way.

[0003]
Dating well beyond the Colonial Period, traditional handcarved wood signs having goldleafed lettering had found a deep rooted place in our culture, and over the years the manufacture of such signs has become a timehonored craft of the signmaking arts. Wood chisels and special knives are the wood crafters basic carving tools used in the time consuming process of hand carving signage works in both relieved and incised modes of carving. Traditionally gold or silver leaf coatings have been applied to the relieved and/or incised surfaces of signage works, so that natural as well as artificial light favorably reflects therefrom to improve the visibility of the signage work, and to display a sense of richness and accentuate the artistic beauty of a signage work itself.

[0004]
The conventional process for producing these handcarved goldleafed wood signs is manual, slow and laborious, and although expensive, they are of distinct beauty and treasured by many.

[0005]
Yet while hand carved wood signs with goldleaf lettering are highly desired articles of manufacture, the traditional process by which they have been made, has tended to make them time intensive, too expensive and thus out of reach for the greater number of persons who otherwise would desire to own such a sign customized to their needs, interests and taste.

[0006]
Hitherto, the art of making goldleafed handcarved wood signs has retained its traditional method of manufacture, with the exception of a minor development involving the use of an overhead projector to transfer a layout pattern to prepared wood. Such a layout transfer technique is described in Volume 15 of Fine Woodworking, March 1979, in an article at pages 7273 entitled “Routed Signs: Overhead Projector Transfers Layout To Prepared Wood” by Frederick Wilbur. Using architectural stickon letters, a few parallel lines and a design concept, a sign layout is mockedup on a piece of transparent plastic film. Using an overhead projector, the layout is transferred onto the prepared wood.

[0007]
In contrast with wood carving signmakers universally eschewing, as a matter of convention, any and all computerassistance in practicing conventional methods of manufacturing goldleafed carved wooden signs, the signmaking industry in general, has nevertheless been effected by the application of computeraided design, computeraided manufacturing and computerized numerical control technology.

[0008]
Hitherto, several computeraided signmaking systems employing computeraided design (CAD) and computeraided manufacturing and computer numerical control (CNC) based technology, have been developed and are presently available.

[0009]
However, such signmaking systems and methods using CAD/CAM technology have been limited to the production of routed and cutout type signs. In contrast, because of its nature, the art of carving traditional goldleafed wood carved signs has remained in the field of art wherein wood carvers use only gouges, knives, chisels and hammers. Thus, it is now in order to briefly describe in the following paragraphs, these inherently limited CAD/CAM signmaking systems and methods.

[0010]
Prior art computeraided signmaking systems allow a signmaker to design two dimensional signage works on twodimensional CAD systems, and to cutout or routein characters, shapes, designs and parts thereof so designed, using cutting tools moving under the guidance of a computeraided machining system, which includes, a computerized numerically controlled (CNC) axially rotating routing tool. However, the cutting and routing functions achieved by the prior art CAD/CAM signmaking systems are limited in several significant ways.

[0011]
In general, signage works formed into signboards by prior art CAD/CAM signmaking systems, are routed thereinto by operation of a routing tool moving in a single plane, with single pass operations. The outlines of the characters are formed by a rotating router tool bit moving in a plane, routing out uniform grooves in the signboard within the plane. Notably, the uniform grooves formed in the signboard, have the crosssectional shape of the rotating tool bit performing the routing operation, and are identical along the entire lengths of the members of alphanumeric characters. In some cases, multiple passes of the routing tool along the character outlines is effected, often using tool bit offsetting, to provide desired finished edges, slightly modifying the original uniform groove so formed coextensively within a single plane. These routed signs bear little if any resemblance to, and lack the surface features of, traditional goldleafed wood carved signs, the subject to which the present invention is directed. one example of such prior art signmaking apparatus is described in the sales brochure for the “System 48 Plus” of Gerber Scientific Products, Inc. of Manchester, Conn., wherein a computeraided signmaking system is disclosed. Specifically, the “System 48 Plus” signmaking system comprises a computeraided manufacturing system which includes a gantrytype cutting machine which can cut or routeout letters up to 24″ high, or stencilcut sign faces for backlighting. The characters so formed from the system, are square cut or beveled, with an optional finish cut. Also, the system provides control for specifying the total depth of cut, and depth of each pass of the router head. (See pages 4.744.76, IV System Operation of Gerber Scientific Products' System 48 User's Manual, Document No. 599020174, January 1986). However, while the “System 48 Plus” signmaking system allows an operator to make any number of passes from 0″ to 2″ inches deep for efficient routing and finer surface finishes, the system is incapable of carving into a signboard, a signage work comprising characters and designs having threedimensional incised and/or relieved surfaces for which handcrafted goldleafed wood carved signs are noted. In particular, the Gerber “System 48 Plus” is limited to 2½ axes of simultaneous cutting tool motion.

[0012]
Another example of prior art signmaking apparatus is described in the sales brochure for the “CSF 300 Computerized Sign Fabrication System” of Cybermation Inc. of Cambridge, Mass. The brochure discloses a CAD/CAM signmaking system including a router head mounted to the carriage of a CNC gantrytype machine which is limited to 2½ axes of simultaneous motion. Sign layouts, either computerdesigned or conventionally laid out, are programmed and can be called up at the machine by an operator. While the system has a library of preprogrammed geometric parts (i.e., letters and numbers in various typestyles) requiring the operator to enter only the desired dimensions, such parts do not have the threedimensional features characteristic of traditional goldleafed handcarved wood signs, nor is the CSF 300 system capable of carving signs having such surface characteristics and features.

[0013]
Thus, in the art of computerassisted design and manufacture of signage works, the convention has been to use CAD systems to design twodimensional layouts of signage works to be cutout of or simply routedin various signboard materials. In the latter instance, the routed surfaces formed within a single plane of a signboard, are limited to the cutting dimensions of the tool bit employed and moving in the plane thereof.

[0014]
Therefore, there is no teaching or suggestion of a computeraided method or system for producing carved signs embodying signage works which have threedimensional surfaces akin to those characteristic of traditional handcrafted goldleafed wood carved signs.

[0015]
Accordingly, it is a primary object of the present invention to provide a way of doing by computers and machines, that which was done by hand in order to produce carved signs having threedimensional surfaces akin to those characteristic of hand carved goldleafed wood carved signs.

[0016]
Another object of the present invention is to provide a computeraided method of producing carved signs which embody signage works having threedimensional incised and/or relieved surfaces, characteristic of traditional goldleafed handcarved wood signs.

[0017]
It is a further object of the present invention to provide a method of producing carved signs resembling traditional handcarved goldleafed wood signs, wherein the method uses an integration of computeraided design (CAD), computeraided machining (CAM), and computerized numerical control (CNC) technology.

[0018]
The present invention provides a design and manufacturing method for providing computerproduced carved signs embodying signage works having complex threedimensional surfaces.

[0019]
A principal advantage of the method hereof is it allows production of a prototype carved sign within only a few minutes after the design has been completed. As for small volume or customized production, the method requires at most, only a few hours of design time and a few minutes of manufacturing time per carved sign.

[0020]
Another object of the present invention is to provide a carved sign embodying a signage work formed in a signboard by an axially rotating carving tool simultaneously moving along at least three programmable axes under the controlled guidance of a computeraided machining system.

[0021]
A further object of the present invention is to provide a computeraided method of producing carved signs embodying signage works comprising characters shapes and designs having threedimensional incised and/or relieved complex surfaces. According to the present method, the characters are designed on a computeraided design system by creating a threedimensional geometric model thereof, and are carved into a signboard using a carving tool moving under the guidance of a computeraided machining system.

[0022]
Another object of the present invention is to provide a carved sign produced by such computeraided method of design and manufacture.

[0023]
It is an even further object of the present invention to provide a CAD/CAM system for producing carved signs embodying signage works having threedimensional incised and/or relieved curved surfaces. An advantage of the design and manufacturing method of the present invention is that a signage work represented by a threedimensional graphical and numeric model can be exactly reproduced, as a carving in signboards, thereby allowing the use of such threedimensional signage works as trademarks and service marks, registered with the United States Patent and Trademark Office.

[0024]
A further object of the present invention is to provide a method of generating on a computeraided design system, threedimensional computer graphic (or, geometric) models (and numerical coordinate data files for corresponding threedimensional carving tool paths) of threedimensional characters generated from traditional twodimensional characters. Such computeraided design method can be used with the method and system for producing carved signs hereof.

[0025]
Another object of the present invention is to provide a method of designing threedimensional graphical models (i.e., representations) and numerical coordinate data files of threedimensional characters generated from twodimensional characters, using parametric splinecurve and/or splinesurface representations in interpolating curves and surfaces, respectively.

[0026]
Another object of the present invention is to provide a method of manufacturing, carved signs embodying signage work having been recorded from preexisting physical objects using threedimensional surface coordinate measuring methods and apparatus (e.g., instrumentation), based on principles including laserranging, and holography.

[0027]
An even further object of the present invention is to provide a method of generating threedimensional graphical representations and corresponding numerical coordinate data files of a signage work wherein such method employs a computeraided threedimensional solid image processing program on the CAD system hereof. This method provides a designer with the capability of precisely mathematically subtracting (e.g., using a computational process on the CAD system), threedimensional solid stock material from a threedimensional solid model of a signboard which is in mathematical union with the solid model of a carving tool that is translatable within the CAD systems' threedimensional coordinate system, using a threedimensional or twodimensional stylus or a mouse. In at particular, this method involves providing a solid geometric model (i.e., threedimensional solid graphical representation) of a carving tool and of signboard constituting material, and performing therewith, threedimensional solidimage processing. A principal advantage of this CAD method is that it provides a highly flexible way in which to render a desired threedimensional model (e.g., graphical representation) from which can be generated, numerical coordinate data file(s) for a threedimensional composite tool path corresponding to a signage work to be carved in a real signboard using a particular carving tool or tools of the present invention.

[0028]
Yet a further object of the present invention is to provide a computeraided carved sign design and manufacturing system on which the methods hereof can be computerprogrammed, and wherein the design and manufacturing system comprises in part, a computeraided design system that can automatically generate and display a computersimulation of the carving tool motion required to produce the desired signage work carved in a signboard. The design and manufacturing system of the present invention also includes a computeraided carving system having at least a threedimensional numerical control (NC) machining (i.e., tool path) program, supported by a CAD/CAM computer.

[0029]
Other and further objects will be explained hereinafter, and will be more particularly delineated in the appended claims, and other objects of the present invention will in part be obvious to one with ordinary skill in the art to which the present invention pertains, and will, in part, appear obvious hereinafter.
SUMMARY OF THE INVENTION

[0030]
The present invention uses an integration of computeraided design, computeraided manufacturing, and computer numerical control technology to provide a computeraided design and manufacturing process for producing carved signs having surface properties and features characteristic of traditional handcrafted goldleafed wood carved signs.

[0031]
In accordance with the principles of the present invention, the method for producing carved signs hereof comprises designing on a computeraided design (CAD) system, a threedimensional graphical model (i.e., representation) of a signage work having threedimensional surfaces to be carved in a signboard. On the computeraided design system, a desired mathematical (e.g., numerical) representation of the signage work is determined. Thereafter, the desired mathematical representation, which can be in one of many possible and desirable formats, is provided to a computeraided machining (CAM) system including a CNC machine tool having a carving tool. The material constituting the signboard is removed using the carving tool moving under the controlled guidance of the computeraided machining system, to leave in the signboard, a threedimensional carved pattern corresponding to the threedimensional graphical model of the signage work. The threedimensional carved pattern in the signboard has threedimensional surfaces corresponding to the three dimensional surfaces of the threedimensional graphical model of the signage work.
DESCRIPTION OF THE DRAWINGS

[0032]
For a further understanding of the objects of the present invention, reference is made to the following detailed description of the preferred embodiment which is to be taken in connection with the accompanying drawings, wherein:

[0033]
[0033]FIG. 1 is a perspective view of an example of the design and manufacturing equipment required to provide a carved sign manufactured in accordance with the preferred embodiment of the design and manufacturing method of the present invention;

[0034]
[0034]FIG. 2 is a schematic block diagram of the computeraided design and manufacturing system for producing carved signs hereof, shown in FIG. 1;

[0035]
[0035]FIG. 3A is a perspective view of a carved sign produced by the method hereof, showing the emulated geometrical features of traditional handcarved wood signs;

[0036]
[0036]FIG. 3B is an elevated crosssectional side view of a carvedsignboard embodying a signage work produced by the method hereof illustrating the threedimensional nature of the “center line” curves of the carved grooves incised therein;

[0037]
[0037]FIG. 4A is a plan view of a twodimensional graphical model (i.e., representation) of a layout of an alphanumerical signage work displayed on the highresolution color graphics display terminal of the computeraided design system hereof;

[0038]
[0038]FIGS. 4B and 4C are different scaled perspective views of a threedimensional graphical model of components of the signage work “SAGAMORE” shown in FIG. 3A, which are typically displayed on the color graphics display terminal during the process of generating threedimensional graphical representations of alphanumerical characters from twodimensional graphical representations (e.g., characteristic outlines) thereof, in accordance with the principles of the present invention;

[0039]
[0039]FIGS. 4D and 4E are different scaled perspective views of threedimensional composite carving tool paths, shown in association with respective characteristic outlines of the threedimensional graphical models of the alphabetical characters “SA” illustrated in FIGS. 4B and 4C;

[0040]
[0040]FIG. 4F is a plan view of a threedimensional graphical model of the numerical character of the numerical character “40” of the signage work of FIGS. 3A and 4A hereof;

[0041]
[0041]FIG. 4G is a perspective view of the threedimensional graphical model of the numerical character “40” illustrated in FIG. 4F;

[0042]
[0042]FIG. 4H is a side view of the threedimensional graphical model of the numerical character illustrated in FIGS. 4F and 4G;

[0043]
[0043]FIGS. 41 and 4J are different perspective views of three dimensional composite carving tool paths graphically shown in association with the characteristic outlines of the threedimensional graphical models of the numerical character “4” illustrated in FIGS. 4F, 4G, and 4H hereof;

[0044]
[0044]FIG. 4K is a perspective view of the threedimensional composite carving tool paths graphically shown in association with respective characteristic outlines of threedimensional graphical models of three alphanumeric characters “SA 4” illustrated in FIGS. 4A, through 4J hereof; and

[0045]
[0045]FIG. 5 is a chart showing several conventional sweeps of gouges and chisels positioned alongside corresponding tool bits for use with the axially rotating carving tool hereof, as to emulate conventional carving operations using method and apparatus of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0046]
It is now in order to describe in a best mode embodiment, the details of the design and manufacturing method and apparatus for producing carved signs embodying signage works having threedimensional incised and/or relieved carved surfaces, in accordance with the principles of the present invention.

[0047]
Referring now to FIG. 1, therein is shown an example of a computerproduced carved sign (CPCS) design and manufacturing system 1, although many different system configurations are possible and would be evident hereinafter to those skilled in the art. From this description, for purposes of illustration, the CPCS system 1 includes a computeraided design/computeraided machining (CAD/CAM) work station 2, a CAD/CAM computer 3 including software packages, and a CAM system

[0048]
The CAD/CAM work station 2 includes a keyboard 5 for providing instructions and data to the CAD/CAM computer 3 via a connection 6. For reviewing the design, a threedimensional highresolution color graphics display unit 7 having a view screen 8 is part of the CAD/CAM work station 2. In the preferred embodiment, the threedimensional high resolution color graphics display terminal, can be the Iris 3030 workstation from Silicon Graphics, Inc. of Mountain View, Calif.

[0049]
As illustrated in FIG. 2, the CAD/CAM work station 2 can be designated as having several other computerassisted design tools, such as three and twodimensional “object” coordinate measuring apparatus, and methods used in connection therewith. An example of twodimensional coordinate measuring apparatus would be a digitizer tablet 9, and an example of threedimensional coordinate measuring apparatus 25 would be the Cyberscan™ laserbased noncontact height profiling system, available from Cyberoptics, Inc. of Minneapolis, Minn.

[0050]
As illustrated in FIG. 1, the CAD/CAM computer 3 is shown as a single unit although it may comprise separate systems available from many different manufacturers. The CAD/CAM computer 3 is connected by a connection 10 to the CAM system 4. Information developed on the computer 3 can be optionally transported to the CAM system 4 on standard commercial magnetic media in the appropriate computerized language formats numerically controlled. Alternatively, connection 10 be realized using a modem in accordance with conventional telecommunication principles (e.g., using the telephonic circuits, microwave and/or satellite links). As will be discussed in greater detail hereinafter, the CAD/CAM computer 3 can be used for either manual, semimanual, or automatic generation of carving tool paths, based on the geometry of a part developed in the CAD/CAM computer during the CAD phase.

[0051]
The CAM system as defined herein, is shown in the preferred embodiment as having a gantrytype carving tool 11 mounted over a vacuum type work table 12 on order of the size of a typical signboard used in outdoor commercial environments, such as in front of a law office or other professional building, but it can be much larger or smaller. The carving tool 11 in the preferred embodiment, comprises an axially rotating carving tool, such as an electric or pneumatic router head, which is mounted to a carriage 13 that moves along the gantry structure 14 in response to threedimensional “carving tool path” instructions provided thereto. In the preferred embodiment, the carving tool 11 is provided with five programmable axes of simultaneous motion.

[0052]
In order to properly practice the computerassisted design and manufacturing method of the present invention, the carving tool 11 need only have at least three programmable axes of simultaneous motion. However, while in the preferred embodiment of the present invention, threeprogrammable axes of simultaneous carving tool movement can be employed, five or seven programmable axes of simultaneous carving tool movement can provide certain advantages when carving particular types of threedimensional signage works. Three, five, and seven axes gantrytype machine tools are available from Thermwood Corporation, of Dale, Ind. In particular, the Thermwood Cartesian 5 Aerospace model having five axes of programmable motion, features a computer numerical controller (i.e., machine control unit) from the AllenBradley Corporation, having bubble memory and milling software. The table size available with such a model is 7½ feet by almost 16 feet, the vacuum feature making it most suitable for accurately holding down a signboard with repeatability.

[0053]
The CAM system 2 also includes a computer numerical controller (CNC) referred to hereinafter as the machine control unit (M.C.U.) shown in FIG. 2. The CAM system 2 is in addition to other mechanical material removal systems such as drills, routers, sanders and the like which can find auxiliary application in carved sign manufacturing operations.

[0054]
Referring now to FIG. 2, there is shown a schematic block representational diagram of the CPCS design and manufacturing system 1 of the present invention. As shown in FIG. 1, the system of FIG. 2 also comprises the CAD/CAM work station 2, the CAD/CAM computer 3, machine control unit 15, gantrytype carving tool with axially rotating carving tool 11 and also “a post processor” 16. It also is shown to include a Graphics Library 17, realized as a computer data base in communication with the CAD/CAM computer 3. In order to provide hardcopy printouts (i.e., plots) of a threedimensional graphical or numerical models of signage works, a plotter/printer unit 20 can be provided. Alternatively, screen image reproductions can be provided by photographic equipment.

[0055]
The Graphics Library 17 contains symbolic representations, such as numerical coordinate tool path data files, threedimensional geometrical and graphical (e.g., curve, surface, and solid) models, design documentation and the like, of signage parts including characters, shapes and designs previously designed or otherwise provided. The symbolic representations stored in the Graphics Library 17 hereof can be (i) generated on the CAD/CAM system 1 in accordance with the computerassisted (and automated) design methods of the present invention, and then (ii) stored in the computer data base 17. Alternatively, the symbolic representations in Graphics Library 17 can be produced with the aid of three and twodimensional coordinate measuring methods and apparatus to be described in detail hereinafter. Thereafter they can be called up by a designer at the work station 2 and concatenated with others, using the keyboard of the workstation to display inventory files on the viewing screen of the 3D color graphics display unit 7. Alternatively, the symbolic representations of characters, shapes and designs after having been generated in accordance with the methods hereof, can be copied, postprocessed, and used on other CAD/CAM systems once the original design work has been achieved. Greater details regarding use of the Graphics Library 17 in the step involving designing signage works to be carved in signboards, will be given in a later section of this Description.

[0056]
Referring to FIG. 3A, there is shown a perspective view of a signboard embodying a threedimensional carved pattern produced by the design and manufacturing method and using the apparatus of the present invention. FIG. 3A illustrates how with the computerassisted carving method of the present invention, the “width” of carved grooves can be made to vary in the xy plane. In FIG. 3B, a crosssectional view of the carved sign of FIG. 3A taken along the line 3B3B, is shown. This crosssectional view illustrates the potentially complex nature of the surfaces. More particularly, this view illustrates how the depth of carved “V” and other shaped grooves of a signage work can be made to vary along the z axis as a function of x, y coordinates in the xy plane. Using the design and manufacturing method of the present invention, virtually any type of signage work having simple or complex threedimensional surfaces, can be represented as a threedimensional graphical model on the CAD system of the present invention, and carved into a signboard using, the carving tool of the computeraided machining system thereof, governed by a desired mathematical representation generated from the threedimensional graphical model.

[0057]
At this juncture, it is now in order to briefly describe the mathematical basis underlying the geometrical and graphical modeling and graphical display of curves, surfaces, and solids comprising the computergenerated three dimensional graphical models of the present invention in particular, and threedimensional mathematical representations of signage works and components thereof, in general.

[0058]
In the preferred embodiment, curve, surface and solid generation facilities are provided for representing curved lines, surfaces, and solids drawn in threedimensional space. The following section hereof describes the mathematical basis for the threedimensional curve and surface facilities of the system of the present invention.

[0059]
For purposes of illustration and not of limitation, the CAD/CAM computer system and work station of the present invention, can be realized (i.e., implemented) using the CAMAND 3000 Series™ CAD/CAM System by Camax Systems, Inc. of Minneapolis, Minn. The CAMAND™ 3000 Series CAD/CAM Computer System can include the 3030 Iris Series super workstation from Silicon Graphics of Mountain View, Calif., providing stateoftheart capabilities for high level CAD/CAM usage. This threedimensional engineering/designing workstation can provide the user with a rapid response time with realtime color graphics display, shading capabilities, multiwindowing, and multitasking capabilities.

[0060]
The CAMAX CAD/CAM System includes CAMAND™ Software that provides sufficient CAD/CAM capabilities for the design and manufacturing of computerproduced carved signs having surface features characteristic of traditional goldleafed hand carved wood signs. CAMAND™ Software includes comprehensive features which are suitable for threedimensional graphic (or geometric) modeling, design analysis, documentation, and multiaxis numerical control programming of carved signage works to which the present invention is directed.

[0061]
As an alternative to CAMAND 3000 Series™ System from CAMAX Systems, Inc., the CAD system of the CPCS System hereof can be realized (i.e., implemented) using the ANVIL™5000 CADD/CAM Software System including the OMNISOLID™ Solid Modeling Software System of Manufacturing and Consulting Services, Inc. (hereinafter MCS) of Irvine, Calif. The MCS ANVIL™5000 CADD/CAM System is a fully integrated 3D CADD/CAM software package which provides wireframe, surface and solid modeling, finiteelement mesh generation, analysis, drafting, and numerical control using the same integrated database structure and the same interactive interfaces.

[0062]
MCS's OMNISOLIDS™ Solids Modelling Software module is a Constructive Solid Geometry (CSG)/BoundaryRepresentation (BREP) hybrid system which allows full use of all sculptured surfaces. The data structure of OMNISOLIDS™ Solid Modelling Software Module is a GSG/BREP hybrid. CSG is a method of storing a solid as a series of unions, intersections and differences of simpler solids, or primatives. BREP, Boundary Representation, is a method of storing the faces (i.e., surfaces) of the solids. The OMNISOLIDS™ Solid Modelling Software Module utilizes a combination of these two storage techniques.

[0063]
The mathematical basis for threedimensional curve facility of the preferred embodiment hereof, is now given with respect to the Iris™ curve facility of the CAMAND 3000 Series™ CAD/CAM Computer System.

[0064]
A curve segment is drawn by specifying a set of four “control points”, and a “basis” function which defines how the control points will be used to determine the shape of the curve segment. Complex curved lines in threedimensions representive of carving tool paths (e.g., character “center lines”), and the like, can be created by joining several curve segments endtoend. The curve facility provides the means for making smooth joints between the curve segments.

[0065]
For purposes of the present disclosure, the term “center line” will be hereinafter used much in the way that it is conventionally referred to in Fine Woodworking's On Carving and How to Carve Wood, both works published by Taunton Press.

[0066]
The mathematical basis for the curve facility of the preferred embodiment, can be the parametric cubic curve. The curves in the present application which correspond to the threedimensional “centerline” trough (of carved grooves in the signboard), are often too complex to be represented by a single curve segment and instead must be represented by a series of curve segments joined endtoend. In order to create smooth joints, it is necessary to control the positions and curvatures at the end points of curve segments to be joined. Parametric cubic curves are the lowestorder representation of curve segments that can provide continuity of position, slope, and curvature at the point where two curve segments meet.

[0067]
A parametric cubic curve has the property that x, y, z can be defined as thirdorder polynomials for some variable t:

x(t)=a _{x} t ^{3} +b _{x} t ^{2} +c _{x} t+d _{x}

y(t)=a _{y} t ^{3} +b _{y} t ^{2} +c _{y} t+d _{y}

z(t)=a _{z} t ^{3} +b _{z} t ^{2} +c _{z} t+d _{z}

[0068]
A cubic curve segment is defined over a range of values for t (usually o≦t≦1), and can be expressed as a vector product.

c(t)=a t ^{2} +b t ^{2} +c t+d

[0069]
[0069]
$c\ue8a0\left(t\right)=\left[\begin{array}{cccc}{t}^{3}& {t}^{2}& t& 1\end{array}\right]\ue89e\text{\hspace{1em}}\left[\begin{array}{c}a\\ b\\ c\\ d\end{array}\right]$ $c\ue8a0\left(t\right)=T\ue89e\text{\hspace{1em}}\ue89eM$

[0070]
The curve facility hereof can approximate the shape of a curve segment with a series of line segments. The end points for all the line segments can be computed by evaluating the vector product c(t) for a series of t values between 0 and 1. The shape of the curve segment is determined by the coefficients of the vector product, which are stored in column vector. These coefficients can be expressed as a function of a set of four control points. Thus, the vector product becomes

c(t)=TM=T(BG)

[0071]
where G is a set of four control points, or the “geometry”, and B is a matrix called the “basis”. The basis matrix B is determined from a set of constraints that express how the shape of the curve segment relates to the control points. For example, one constraint might be that one end point of the curve segment, is located at the first control point. Another constraint could be that the tangent vector at that end point lies on the line segment formed by the first two control points. When the vector product C is solved for a particular set of constraints, the coefficients of the vector product are identified as a function of four variables (the control points). Then, given four control point values, the vector product C(t) can be used to generate the points on the curve segment. For a detailed discussion of the various classes of cubic curves, including Cardinal Spline, BSpline and Bezier Spline curve representations, reference can be made to the publication “Parametric Curves, Surfaces, and Volumes in Computer Graphics land ComputerAided Geometric Design” (November, 1981) by James H. Clark, Technical Report No. 221 Computer Systems Laboratory, Stanford University, Standford, Calif.

[0072]
Attention is now accorded to the mathematical basis for the surface facility of the present invention, which in the preferred embodiment, can be the Iris™ surface facility. Threedimensional surfaces, or patches, are presented by a “wire frame” of curve segments. A patch is drawn by specifying a set of sixteen control points, the number of curve segments to be drawn in each direction of the patch (i.e., precision), and the two “bases” which define how the control points determine the shape of the patch. Complex surfaces can be created by joining several patches into one large patch using the surface facility the method for drawing threedimensional surfaces is similar to that of drawing curves. A “surface patch” appears on the viewing screen as a “wire frame” of curve segments. The shape of the patch is determined by a set of userdefined control points. A complex surface consisting of several joined patches, can be created by using overlapping sets of control points and Bspline and Cardinal spline curve bases.

[0073]
The mathematical basis for the surface facility of the present invention, can be the parametric bicubic surface. Bicubic surfaces can provide continuity of position, slope, and curvature at the points where two patches meet. The points on a bicubic surface are defined by parametric equations for x, y, and z. The parametric equation for x is:
$\begin{array}{c}x\ue8a0\left(\mathrm{st}\right)=\text{\hspace{1em}}\ue89e{a}_{11}\ue89e{s}^{3}\ue89e{t}^{3}+{a}_{12}\ue89e{s}^{3}\ue89e{t}^{2}+{a}_{13}\ue89e{s}^{3}\ue89et+{a}_{14}\ue89e{s}^{3}+{a}_{21}\ue89e{s}^{2}\ue89e{t}^{3}+{a}_{22}\ue89e{s}^{2}\ue89e{t}^{2}+\\ \text{\hspace{1em}}\ue89e{a}_{23}\ue89e{s}^{2}\ue89et+{a}_{24}\ue89e{s}^{2}+{a}_{31}\ue89e{\mathrm{st}}^{3}+{a}_{32}\ue89e{\mathrm{st}}^{2}+{a}_{33}\ue89e\mathrm{st}+{a}_{34}\ue89es+{a}_{41}\ue89e{t}^{3}+\\ \text{\hspace{1em}}\ue89e{a}_{42}\ue89e{t}^{2}+{a}_{43}\ue89et+{a}_{44}\end{array}$

[0074]
(the equations for y and z are similar). The points on a “bicubic patch” are defined by varying the parameters s and t from 0 to 1. If one parameter is held constant, and the other is varied from 0 and 1, the result is a cubic curve. Thus, a wire frame patch can be created by holding s constant several values, and using the facility hereof to draw curve segments in one direction, and doing the same for t in the other direction.

[0075]
There are five steps in drawing a surface patch:

[0076]
(1) The appropriate curve bases are defined. The Bezier basis provides “intuitive” control over the shape of the patch, whereas the Cardinal Spline and BSpline bases allow smooth joints to be created between patches.

[0077]
(2) A basis for each of the directions in the patch, u and v, must be specified. Notably, the ubasis and vbasis do not have to be the same.

[0078]
(3) The number of curve segments to be drawn in each direction is specified, where a number of curve segments can be drawn in each direction.

[0079]
(4) The “precisions” for the curve segments in each direction (i.e., u and v) must be specified. The precision is the minimum number of line segments approximating each curve segment and can be different for each direction. To guarantee that the u and v curves segments forming the wire frame, actually intersect, the actual number of line segments is selected to be a multiple of the number of curve segments being drawn in the opposing direction.

[0080]
(5) Using appropriate “path” commands, as for example, of the Iris™ Graphics Library, the surface is actually drawn. The arguments to the “patch” command contain the sixteen control points that govern the shape of the patch, and associated with the x, y, and z of the sixteen control points, there is associated a 4×4 matrix, respectively.

[0081]
Patches can be joined together to create the complex surfaces of threedimensional signage works, by using for example, the Cardinal Spline or BSpline bases, and overlapping sets of control points. In addition, curves and surfaces can be “blended”, smoothed, filled and trimmed by mathematical processing.

[0082]
For a discussion of the mathematical basis for the solid model facility of the preferred embodiment hereof, reference can be made to Chapter 3, Subchapter 4 entitled, “Parametric Volumes” of James H. Clark's Technical Report No. 221, Computer Systems Laboratory, Stamford University referred to hereinbefore.

[0083]
Attention is now given to designing a signage work on the computeraided design system hereof in accordance with the principals of the present invention. In realizing the design and manufacturing method of the present invention, one of several techniques can be used to design on the CAD system hereof, threedimensional graphical models (e.g., threedimensional geometrical representations and/or carving tool path data files) of a signage work to be carved in a signboard. In each embodiment of the method however, there exists a step of modeling in some form or another, the geometry of the components of a threedimensional signage work, and determining an appropriate threedimensional carving tool path provided by NC programming, to render the carved signage work in the signboard.

[0084]
In developing the computerassisted design and manufacturing method of the present invention, careful study has been accorded to the traditional tools of the wood carving signage craft. As illustrated in FIG. 5, such tools include wood carving chisels and gouges of various sweeps and sizes, and in particular, study has been given to the ways in which the various carving functions (i.e., involving traditional wood carving tools) can be emulated using, for example, the axially rotating carving tool 11 having a selected tool bit geometry, moved in threedimensional space under the controlled guidance of the CAM system of the present invention.

[0085]
Additionally, recognition is given to the fact that wood carvers have cut the sides of the grooves (i.e., gouges) of letters at angles ranging from 90° to 120° in order to form the “V” shaped grooves of many tradionally handcarved incised letters. Notably, different wood carvers often select different angles to form the “V” as to reflect light in a preferred manner. In connection therewith, FIGS. 4C, 4D, 4E and 4K in particular, clearly illustrate how the width of a threedimensional carved pattern (such as a groove) can be varied along a threedimensional center line interposed between the inner and outer character outlines, by simultaneously controlling along the z axis, the cutting depth (e.g., z coordinates) of a cutter bit as it is moved along the threedimensional carving tool path in the xy plane of a threedimensional coordinate system.

[0086]
Hereinbelow is described one method in particular which has been developed for carving letters and other alphanumeric characters using the CPCS design and manufacturing system 1 and the carving tool bits illustrated in FIG. 5. This computerassisted design method has been discovered to be a highly effective and most efficient method for designing threedimensional computer graphic models and threedimensional carving tool paths (including numerical coordinate data) for characters, to be used in producing threedimensional carved patterns of threedimensional signage works in sign boards, wherein the carved patterns have incised and/or relieved surfaces characteristic of traditional goldleafed wood carved signs. This particular method will now be described below.

[0087]
Referring to FIG. 4A, a twodimensional computer graphic model (i.e., representation) of a layout of a threedimensional signage work is presented in plan view as would appear on the display terminal 7. FIGS. 4B and 4C illustrate in greater detail two characters (i.e., components or parts) of a threedimensional signage work whose geometry is being modelled on the CAD system. The threedimensional graphical representations of the signage work of FIGS. 4B through 4J, preferably are displayed on the viewing screen 8 using highresolution color graphics software.

[0088]
Referring to FIGS. 4A and 4F through 4J, there is illustrated several principal steps comprising a method of generating threedimensional graphical and numerical models of threedimensional characters from traditional or novel twodimensional characters or shapes, having “outer” (and sometimes “inner”) characteristic outlines 18 and 19 respectively. The sequence of steps for this computeraided design method will now be described in detail.

[0089]
As indicated in FIG. 4A, a twodimensional graphical representation (e.g., the “4” of “40 SAGAMORE”) having “inner” and “outer” characteristic outlines 19 and 18, is displayed (i.e., plotted) in twodimensions (e.g., the xy plane) on the CAD system, such system preferably having highresolution color graphics capabilities. As a matter of design choice, the characteristic outlines can be designated a particular color such as yellow.

[0090]
As indicated in FIG. 4F, a plurality of substantially similar outlines 18A of the twodimensional character (e.g., 4) are generated from the “outer” characteristic outline 18 and a plurality of substantially similar outlines 19A from the “inner” characteristic outline 19 thereof, at a predetermined offset (in millimeters) in a direction towards the inside (i.e., towards the centerline) of the two dimensional character. These “offsetted” characteristic outlines 18A and 19A can be designated as purple, for example.

[0091]
As indicated from the characters of FIG. 4F, in particular, there can arise from this computer graphic design process, the formation of what will hereinafter be termed “islands”, designated by 21A, 21B, and 21C of the character “4” in FIG. 4F. In accordance with the present invention, “island formations” can be thought of as the void or vacant twodimensional spaces remaining within the space between the characteristic outer and inner outlines, 18 and 19 respectively, that is, after the outer and inner characteristic outlines 18 and 19 converge to within a distance apart equivalent to the offset distance. Notably, the character “0” of FIG. 4F has no island formations.

[0092]
When island formations arise in the process of generating threedimensional characters from twodimensional characteristic outlines of characters, shapes, designs and the like, then either manual or programmed generation of “local” characteristic outlines, e.g., 22A, 22B and 22C, for the “islands” 21A, 21B and 21C respectively, must be generated. This procedure ensures that complete threedimensional graphical models of signage works and components thereof can be provided. In such instances, the island characteristic outlines 22A, 22B and 22C can be offset to generate a plurality of island characteristic outlines as illustrated in FIG. 4F.

[0093]
The plurality of “inner” and “outer” similar outlines (i.e., offsets) illustrated in FIG. 4F in particular, are then displayed on the CAD system's color graphics viewing screen, for review. The general appearance of these geometrically similar outlines are that of contour lines, of a contour map. But as will be illustrated in the description of this particular method, providing such similar outlines principally, although not solely, serve to help the designer determine on the CAD system (i) the depth (e.g., z coordinates) and (ii) the location (e.g., x, y coordinates) of the threedimensional “center line” curve of the threedimensional character produced from a transformed twodimensional character, projected into the threedimensional space.

[0094]
As illustrated in FIGS. 4G and 4H, each of the geometrically similar outlines are then translated (i.e., projected), a predetermined distance along the third dimension (e.g., z axis) of the CAD systems' threedimensional coordinate system. As mentioned hereinabove, this step is helpful in assisting the designer to determine the location where the threedimensional “center line” of the twodimensional character will be drawn.

[0095]
Thereafter, using the threedimensional graphical model of FIG. 4G, a plurality of points are interactively introduced in the threedimensional coordinate system, at locations corresponding to points lying along what can be visualized to be a threedimensional tool path, along which the apex (i.e., tip) of an axially rotating cutting tool of predetermined cutting dimensions, moves under the guidance of the CAM system hereof. The interactive introduction of points can be achieved using a “stylus” or “mouse” device well known in the computeraided design arts. These points are selected so that when the axially rotating cutting tool 11 is moved along the threedimensional tool path, a desired threedimensional carved pattern having desired threedimensional surfaces of a visualized signage work, is formed in a signboard. Notably threedimensional surfaces of the carved pattern will correspond to the threedimensional surfaces of the threedimensional graphical model (i.e., representation) of the threedimensional alphanumerical character. As discussed in the curve mathematics section provided hereinbefore, the plurality of points are then appropriately interpolated using parametric splinecurve representations, to render the coordinates of a composite threedimensional carving tool path 23 illustrated in FIGS. 4I and 4J. The carving tool path 23 when taken with a threedimensional graphic model of a carving tool, corresponds to the threedimensional carved pattern that is associated with the so designed threedimensional graphical model of the threedimensional character. Thereafter, the interactively introduced points can be erased for display purposes.

[0096]
In connection with the abovedescribed method of the present invention, a threedimensional graphical model and corresponding numerical coordinate tool path data file(s) can be generated on the CAD system hereof, from a corresponding twodimensional graphical model (e.g., characteristic outline) of the alphanumeric character. The alphanumerical character can be of any sort regardless of type style or font, and with or without serifs, a feature such as a fine crossstroke at the top or bottom of a letter. The threedimensional graphical representations, numerical coordinate carving tool paths, and other mathematical representations derived therefrom, once having been generated, can be stored in nonvolatile memory (e.g., ROM) and can be used to create the database of the Graphics Library of the present invention, as discussed hereinbefore with reference to FIG. 2B.

[0097]
The tool path data file so generated by the abovedescribed design method, is then subject to post processing, an operation which involves processing the tool path data file to produce complete, machineready files, expressed in machine (i.e., assembly) or binary logical languages. In the post processor, the tool path data is matched (i.e., interfaced) to a particular CNC machine tool and machine control unit (MCU) combination. The output of the post processor can be generated for paper tape, magnetic memory storage or direct numerical control (DNC).

[0098]
Notwithstanding post processing being a subject well known and understood in the art of NC programming, reference is made to a paper entitled “GPosting To NC Flexibility”, by the Computer Integrated Manufacturing Company, of Irving, Tex., and reprints from Modern Machine Shop of Cincinnati, Ohio. This paper provides a further discussion on the “generalized postprocessor approach” utilized in simplifying NC workpiece programming and in making such programs function on different makes of similar types of machine tools.

[0099]
In the preferred embodiment , the output of the post processor corresponds to a threedimensional composite tool path data file, and threedimensional graphical representations (i.e., models) of each alphanumerical character. The post processor output can also be used to create the extensive Graphics Library of numerous sets of threedimensional alphanumerical characters of distinct typestyles (i.e., fonts). The computersoftware based Graphics Library of the CAD/CAM sign carving system 1 of FIG. 2B, can provide a robust inventory of threedimensional characters. The data files of these threedimensional characters can be simply accessed by a designer at the work station 2, for purposes of designing a threedimensional layout of a threedimensional signage work. Once designed, the threedimensional graphical model of the signage work can be displayed, reconfigured, and transformed to the designer's liking, and after generation of threedimensional tool path data files and post processing thereof, provided to the CAM system 4 in order to carve the corresponding threedimensional signage work into a signboard, by taking necessary and sufficient steps.

[0100]
In addition to the abovedescribed method of designing threedimensional graphical models and tool path data files of threedimensional alphanumerical characters derived from twodimensional alphanumerical characters, an alternative method of achieving the same has been developed. This alternative method will now be described and explained below, after making a few preliminary remarks appropriate at this juncture.

[0101]
As discussed hereinbefore, the methods thus described include that prior to carving any form of threedimensional signage work in a signboard, the geometry of the design of the signage work is first specified by a computer graphic model from which thereafter a numerical coordinate (threedimensional tool path) model is produced. In the present invention, the computer graphic and numerical coordinate tool path models of a signage work are prepared using computeraided design and manufacturing techniques, all of which are based upon computer graphics and computational geometry, the latter being a subject which is given treatment in “Computational Geometry for Design and Manufacturing (1980)” by I. D. Faux and M. J. Pratt, published by John Wiley and Sons.

[0102]
Notably, in the field of geometric (to be contrasted with graphical) design, if the design of a threedimensional signage work has complex surfaces, as can many wood carved signage works, then precise surface descriptions would need to be given for those complex surfaces, prior to the determination of tool paths and the output of the post processor. This therefore makes geometric modeling using geometric primatives, a potentially time consuming process in some cases, as the nature and precision of the surface description given to a signage work is a question of mathematical form. Mathematical form, on the other hand, is a matter regarding the type of mathematical functions used to describe complex threedimensional curves, surfaces and solids of signage works, wherein the threedimensional surfaces thereof are characteristic of traditional goldleafed handcarved wood signs, and which are to be machinecarved in a signboard in accordance with the present invention.

[0103]
In contrast with geometric design, graphical design on the CAD/CAM system of the present invention, can employ threedimensional coordinate measuring methods and aparatus, which usually does not require production of geometric descriptions (i.e., functions) and can produce numeric models of threedimensional objects to be carved in a signboard in accordance with the principles of the present invention. The advantages of each type of model used in computeraided sign carving according hereto, will hereinafter appear obvious to those with ordinary skill in the art to which the present invention pertains.

[0104]
It is also within the contemplation of the present invention, that there can appear at times, the need to employ additional modeling techniques based on alternative mathematical structures and processes operationally supported within the CAD system of the CPCS design and manufacturing system hereof. It has been discovered that this is especially the case when desiring to produce carved signs embodying signage works having threedimensional surfaces akin to those characteristic of traditional handcrafted goldleafed wood carved signs in particular, and having relieved and/or incised carvings of characters and designs, in general.

[0105]
In particular, in IEEE Computer Graphics and Applications Journal of January 1984, a paper is presented entitled “ComputerIntegrated Manufacturing of Surfaces Using Octree Encoding” by Yamaguchi et al. The paper presents an algorithm for automatically generating from an octree description, numerical coordinate tool paths containing the data that a numerical control milling machine requires to manufacture a part. The octree data structure, representing a threedimensional object by hierarchically organized cubes of various sizes, facilitates the performance of boolean operations and tool and work piece “interference” checking, and provides an approximate representation of smooth surfaces to any required accuracy. Also, since the octree model has a very simple data structure, the automatic generation of various types of carving tool paths is possible. Accordingly, the use of octree data structures, operations, and algorithms can be used with the CPCS design and manufacturing system hereof, to design threedimensional graphical models of signage works having threedimensional incised and/or relieved surfaces.

[0106]
When graphically modeling signage works having certain surface topologies, it has been discovered that other CAD methods can be advantageously employed in designing and manufacturing carved signs in accordance with the principals of the present invention.

[0107]
Additionally, as discussed hereinbefore, the method of the present invention, can make use of parametric splinecurve, splinesurface, and splinevolume (i.e., solid) representations as mathematical structures for geometric modeling of the threedimensional surfaces of a signage work. Examples of such splinecurve and surface representations are defined and described in the IEEE Computer Graphics and Applications Journal, in the following articles: “Parametric Spline Curves and Surfaces” by B. A. Barskey, February 1986; “Rational BSplines for Curve and Surface Representation” by Wayne Tiller, September 1983; “Rectangular VSplines” by G. M. Nielson, February 1986; “A Procedure For Generating Contour Line From BSpline Surface” by S. G. Sutterfield and D. F. Rogers, April, 1985.

[0108]
Herebelow, using one of several known or yettobediscovered parametric spline curve or surface representations, an alternative method is presented for generating, on the CAD system, a threedimensional graphical model (i.e., representation) of a twodimensional shape having at least one characteristic outline. This method comprises displaying in two dimensions on the CAD system, the twodimensional graphical representation of the characteristic outline of the shape. From this twodimensional graphical representation, the surface within the “characteristic outline” thereof is subdivided into a plurality of “surfaces patches”, each of which can be independently created and smoothly connected together using surface mathematics as hereinbefore described. A spline surface representation of a particular type, can be selected as a basis for patches of the threedimensional curved surfaces of the threedimensional graphical model (i.e., representation) generated from the twodimensional character. Interactively, an a array of control points can then be introduced in threedimensional space, to control the desired shape of the parametric splinesurface representations so to design the “surface patches” comprising the threedimensional graphical model generated from the twodimensional shape or character. The array of control points for each surface patch, are then interpolated using a spline surface representation to thereby generate the individual surface patches comprising the threedimensional graphical model. From the resulting threedimensional graphical model, a corresponding tool path can be automatically or interactively (i.e., manually) generated.

[0109]
In connection with the design and manufacturing method of producing carved signs in accordance with the present invention, there are two prior art computeraided methods which can be used in the process of designing from twodimensional alphanumerical characters, threedimensional graphical models thereof.

[0110]
U.S. Pat. No. 4,589,062 to Kishi et al. incorporated herein by reference, discloses a method of creating curved surfaces which can be used in the design step involving the formation of threedimensional graphical models of components of threedimensional signage works. In particular, the method of U.S. Pat. No. 4,589,062 is an “interactive” method, which involves defining on a first section curve (e.g., characteristic outline), a first correspondence point which corresponds to a second correspondence on a second section curve (e.g., center line), and then generating intermediate section curves in accordance with the first and second correspondence points. In essence, such method involves moving and transforming a first section curve of two given section curves, until the first second curve is superposed on a second section curve. The major advantages thereof is that curved surfaces featuring subtle changes can be generated with increased degrees of freedom and created with accuracy. According to the present invention, the method of U.S. Pat. No. 4,589,062 can be employed in the process of producing a threedimensional graphical model (i.e., representation) of a signage work in general, and threedimensional graphical model of a threedimensional character generated from a twodimensional character having at least one characteristic outline, in particular.

[0111]
Another method which can be used in the design step of the method of the present invention, involves automatically creating threedimensional sculptured surfaces from sectional profiles designated on design drawings only. FAPT DIEII software from General Numeric of Elk Grove Village, Ill., provides such facility. For sectional profiles, curves on an optional plane in a space are classified into basic curves and drive curves. For example, assume that one basic curve and two (i.e., first and second) drive curves are designated on a design drawing. Sculptured surfaces are created by gradually changing the profile of the first drive curve to the second drive curve when the first drive curve moves toward the second drive curve along the basic curve. As applied to the present invention, the first and second drive curves can represent the effective crosssections of an axially rotating carving tool disposed at two different points along the z axis herein. The basic curve can represent the center line of a carved groove in a signboard.

[0112]
While the above methods of generating threedimensional graphical models of characters may satisfy most designers of computerproduced carved signs, especially those designing signage works limited to lettering, the present invention understands that there are, nevertheless, CAD designers who desire to feature in their threedimensional signage works, shapes and designs other than alphanumerical characters such as those commonly seen in handcrafted “chip” carvings. In such situations, the designer will need to generate on the CAD system, threedimensional graphical models having complex three dimensional surfaces. In such an event, the designers will require certain computerassisted geometric modeling and NC tool path generation capabilities. This is to ensure that complex signage work components can be efficiently and effectively designed, composite tool path graphics displayed, and composite tool path numerical data generated therefrom and proven by computer simulation on the CAD system or by carving signboards with the CAM system of the present invention.

[0113]
In accordance with the principles of the present invention, the components of a complex signage work can be modelled with any combination of “wire frame” and surface (or solid) primitives, including spline curve and surface representations. From the Graphics Library 17 in the system diagram of FIG. 2B, a designated computer program can access previously recorded two and threedimensional graphical designs for creation of tool paths which can be dynamically displayed and interactively joined, and edited. This provides a visual representation of the exact tool paths relating to the graphically designed part. The NC tool path data can be in one of several formats, and an appropriate post processor will produce either paper tape, or magnetic recordings, or direct output for controlling the axially rotating carving tool 11 hereof preferably having five programmable axes of simultaneous movement as described hereinbefore.

[0114]
The present invention also contemplates that there are instances when a designer will desire additional freedom in designing a threedimensional graphical model of a signage work, that is, as compared with the abovedescribed computeraided design methods. It has been discovered that in such instances, it may even be desired to have the capability of representing threedimensionally on the CAD system hereof, the removal of “solid” signboard constituting material, as does a carver skillfully utilizing conventional tools of the trade, such as chisels, gouges and hammers. In connection with such design capability, an alternative computeraided design method has been developed and will be described hereinbelow.

[0115]
This alternative computerassisted design and NC programming method teaches “mathematically” subtracting (using Boolean operations), solid “stock material” (i.e., signboard material) representations from a signboard represented in the threedimensional CAD system, which uses a computeraided carving tool. Therein, the carving tool(s) is (are) represented on the CAD system in the form of a “solid” threedimensional graphical structure representing the “effective” solid geometry of a specified tool bit in operation. The carving tool is also displayed on the visual display unit of the CAD system, and can be moved on the screen using a joystick, light pen or other conventional device. Between the threedimensional images of the solid signboard and carving tool bit, a computationalbased “threedimensional image subtraction” process comprising “Boolean operations”, is performed to generate a threedimensional graphical representation of a signage work. Therefrom, tool path data associated with a particular threedimensional, graphically represented carving tool, is automatically generated. The steps of the process are described below.

[0116]
Using solid geometry, the designer models (i.e., represents) on the CAD system, the carving tool as well as the signboard and then removes (i.e., mathematically subtracts) the from the solid model of the signboard, the graphically represented stock material of the solid signboard model, over which the solid models (i.e., numeric and graphicsbased threedimensional graphical representations) of the carving tool bit and signboard, overlap. As the threedimensional carved patterns are being defined, both the tool path graphics data and the tool itself can be displayed. At the same time or thereafter, tool path numerical data files thereof can be automatically generated using known computational processes.

[0117]
The process described hereinabove involves threedimensional solidimage subtraction and has the advantage of automatic tool path generation. Thus, this method of designing threedimensional models of a signage work requires implementation of a threedimensional image subtraction technique realized by a computeraided process on the CAD/CAM computer 3. The computeraided process effectuates the removal of threedimensionally represented “solid” stock material in “union” (i.e., overlapping in 3D space) with the position of the solid geometrical model of a carving tool (e.g. axially rotating carving tool bit). With this process, the removal of solid stock material in “union” with the solid carving tool model is achieved by mathematical subtraction (i.e., difference calculations) from a solid geometrical model of the signboard and in a manner which is analogous in some respects to the modus operandi of sign carvers employing manual, timehonored carving tools and procedures.

[0118]
In realizing the abovedescribed method, an enhanced version of one of the CAMAX CAMAND™ and the MCS ANVIL5000 OMNISOLIDS™ solid (i.e., volume) modeling computer software program packages can be used to impliment the hereinabove described design process of the present invention. With such a process, a means is provided for mathematically or “computer graphically” carving signage works and automatically generating numerical coordinate tool path data therefor on the CAD/CAM system hereof. In implimenting the abovedescribed threedimensional solidimage subtraction/automatic tool path generation process, advantages can be derived by using work station software from Weber Systems Inc. of Brookfield, Wis. In particular, the work station software can allow an operator/designer practicing the present invention, to simultaneously view four different views of the Booleanbased computational process involving solid models of the carving tool and stock material (e.g., signboard).

[0119]
In connection with the CAD method hereinbefore described, focus is now given to FIG. 5 wherein examples of carving tool bits of various geometries are illustrated, and which can be used with the design and manufacturing method of the present invention. Therein, the chart shows several conventional sweeps and gouges and chisels positioned alongside corresponding tool bits for use with axially rotating carving tool 11, which are capable of emulating conventional hand carving operations in accordance with the principles of the present invention. Also, as illustrated in FIG. 2, threedimensional solid graphical (and numerical) models of the various carving tool bits illustrated in FIG. 5 can be stored in memory 24, and called up when desired by a designer or program.

[0120]
The present invention also contemplates that there are instances when a designer will desire to design (i.e., define) a geometric model of a signage work using at least one or more of the parametric curve, surface, and solid generation facilities of the system hereof, and allow the CAD/CAM computer 3 to automatically generate the tool path parameters (e.g., carving tool specifications, numerical coordinate tool path data, spindle and feed speeds, etc.), tool entry methods, and clearance planes, in a language compatible with the postprocessor available.

[0121]
There will also be times when a computerassisted designer may desire to carve a threedimensional pattern or design of a preexisting “physical” object, alongside or around carved lettering comprising in combination therewith, a composite signage work. Realizing that creating a graphical (or geometrical) model of preexisting physical objects requires substantial time at the work station 2, a threedimensional graphical and numerical model of such signage work can be designed (i.e., provided) by recording the coordinates of the threedimensional surfaces of the physical object to be carved in the signboard, as to produce a threedimensional graphical and numerical model of such signage work or component thereof. Using automatic or manual tool path generation techniques and one of several carving tools, a numerical coordinate data file of a composite tool path therefor can be produced.

[0122]
This CAD technique offers the advantage of obviating the need to manually generate a threedimensional graphical model of the physical object using computational geometry and the like, but rather utilizes threedimensional surface coordinate measuring methodologies, based in part on principals of holographic imaging and optical memory storage. In such instances, “threedimensional coordinate measuring” methods and apparatus can be used in the step of designing (i.e., producing or providing) a threedimensional graphical model of a signage work, in accordance with the design and manufacturing method of the present invention. In particular, a laserbased noncontact height profiling system can be employed to carry out methods of measuring threedimensional coordinates of the surfaces of a low profiled physical object (i.e., digitizing threedimensional objects) to be carved in a signboard. An example of such threedimensional coordinate measuring apparatus 25 diagrammatically illustrated in FIG. 2, is the Cyberscan™ profiling system available from Cyberoptics Inc., of Minneapolis, Minn. and as the corporate name suggests, optical principles can be applied to achieve control processes. In the case of the present invention, the control processes would be the CAM system 4 guiding the carving tool 11 in accordance with carving tool paths generated from a threedimensional graphical model of the preexisting physical object.

[0123]
Another approach using threedimensional coordinate measuring methods and apparatus can involve utilization of holographic recording methods and equipment. In such instances, a threedimensional graphical model can be produced by holographically recording a physical object to be carved in a signboard, using holographic equipment. The holographically recorded image of the physical object can be stored and digitally processed to provide in a suitable computer graphic format, a threedimensional graphical model of the physical object. From this threedimensional graphical model, suitable carving tool paths (i.e., numerical data files) can be generated using either manual, semimanual or automatic tool path generation techniques.

[0124]
Alternatively, a handheld stylus called the “3 Space Digitizer” from Polhemus Navigation Sciences, of Colchester, Vt., can be used to enter x, y, and z coordinate data of threedimensional physical objects or models, into a properly interfaced CAD/CAM system. Using a Unigraphics™ CAD/CAM workstation from The McDonnel Douglas Corporation, an alphanumeric terminal initiates the digitizer task, and the 3 Space Digitizer can be used to enter complex geometry of nonmetallic objects (e.g., to determine the x, y, and z coordinates of points located on a 3D model or object). The 3D Space Digitizer transmits this data to a host computer which includes a C.P.U., tape drive, and disk drive, and stores data in userspecified part files and interfaces with the Unigraphics™ workstation.

[0125]
The 3D Space Digitizer can be used to measure the coordinates (i.e., digitize the space dimensions) of threedimensional physical objects that are to be made part of signage works, employing one or more of incised, relieved, or applique modes of carving. From so produced numerical models of these objects, a threedimensional graphical model thereof can be displayed, and numerical coordinate tool path data files generated.

[0126]
Twodimensional recording of surface coordinates of preexisting physical objects can also be performed using 2D coordinate measuring methods and apparatus to provide twodimensional characteristic outlines thereof. Thereafter, characteristic outlines so produced, can be used to generate therefrom, threedimensional graphical models in accordance with the methods described hereinbefore.
OPERATION OF PREFERRED EMBODIMENT HEREOF

[0127]
It is appropriate at this juncture having described hereinbefore methods and apparatus of the present invention, to now describe the operation of the preferred embodiment of the CAD/CAM design and manufacturing system 1 of the present invention during an explemary design and manufacturing cycle based on the principles thereof.

[0128]
Visualizing in ones mind a signage work to be carved on a signboard, a designer using the design and manufacturing method hereof, has great flexibility and numerous design tools from which to choose. More specifically, an operator using the CPCS CAD/CAM system hereof has several options in producing a threedimensional graphical model of a signage work to be carved in a signboard.

[0129]
One method of designing a threedimensional graphical model of a signage work is to apply at the workstation 2, one of the various computeraided design methods described hereinbefore. For example, using on the CAD system hereof, the method of generating threedimensional alphanumerical characters from corresponding twodimensional alphanumerical characters can produce a threedimensional graphical (and numerical model) model of a composite signage work comprising such characters.

[0130]
Alternatively, threedimensional coordinate measuring methods and apparatus can be used through the workstation 2, to provide a threedimensional graphical model of a physical object to be used as a signage work which is intended to be carved in a signboard according to principles of the present invention.

[0131]
Yet, on the other hand, a designer using one of the computeraided design methods described hereinbefore can visualize a signage work and applyingsuch design methods, produce a threedimensional graphical model of the signage work.

[0132]
From the threedimensional graphical model however produced, a mathematical representation of the signage work, such as a numerical coordinate (tool path) data file, can be generated and provided to the CAM system 4 having carving tool 11. The material constituting the signboard is then removed using the carving tool 11 moving under the controlled guidance of the CAM system 4, to leave in the signboard, a threedimensional carved pattern corresponding to the signage work. Notably, the threedimensional carved pattern in the signboard will have threedimensional surfaces corresponding to the threedimensional surfaces of the threedimensional graphical model of the signage work.

[0133]
It is herein noted that during the machine carving operation, tool change may be required according to the designed carving program (e.g., tool path data file) which has been provided to the Post Processor 16 of the CAM system 4. In such instances, carving tool bits of the type illustrated in FIG. 5, can be accessed from tool storage 26 during a carving operation, and changed in accordance with the carving program whereafter the carving operation can resume. Tool change can occur as often as desired.

[0134]
Also in instances where “chisel or gouge markings” formed in the threedimensional carved grooves are desired, an approach employing several levels of carving processes (and thus multiple composite carving tool paths) can be adopted and CNC programmed. In such a multistage carving process, the later stages of the carving process can include carving tool movement to create the chisel and/or gouge markings, as to emulate the textural appearance of such traditional handcarved wood signs.

[0135]
After a signage work has been carved into the signboard using the computeraided design and manufacturing method of the present invention, finishing operations can then be performed on the carved sign according to conventional principles and techniques.

[0136]
For example, the carved signboard can be prepared for painting and gold leafing. In cases where the signboard is constituted of wood, conventional wood finishing techniques can be employed. Examples of such techniques can be found in How to Carve Wood by Richard Butz cited hereinbefore. Thereafter, goldleaf material can be applied to the signboard in accordance with techniques known in the traditional wood carving arts. Discussion of such applicable techniques can be found in Chapter IX entitled “Laying and Burnishing Gold” of Writing & Illuminating & Lettering (1983) by Edward Johnston, published by Adam & Charles Black of London, England, and by the Taplinger Publishing Co., Inc. of New York, N.Y. In the case where vinyl or like plastic is used as signboard constituting material, conventional goldleafing can be obviated, and chrome or gold spray or deposition processes can be used. Alternatively where the signboard is constituted of metal, electroplating processes can be used to deposit light reflective coatings over threedimensional carved surfaces.

[0137]
Attention is now accorded to the types of materials out of which the signboards may be constituted. It has been discovered that aside from woods such as for example, mahogany, pine, redwood and cedar, other materials such as acrylic, vinyl, polycarbonate, styrene, aluminum, brass and foam board, also provide suitable signboard materials for practicing the method of the present invention.

[0138]
There are several parameters which should be considered prior to carving using the design and manufacturing method of the present invention. Specifically, as regards spindle speeds, (i.e., of the axially rotating carving tool 11), it has been discovered that speeds within the range of 15,000 to 24,000 RPM have provided excellent results when computercarving mahogany wood. However, when using wood, cutting directions of the axially rotating carving tool hereof must also be considered in view of the grain of the wood. It has been discovered that information regarding “grain” of particular wood signboards to be carved using the methods hereof, can be model on the CAD system and used to generate tool paths which consider the grain of the wood signboard.

[0139]
In the present invention sanding operations can be executed using axially rotating sanding tools of appropriately configured dimensions, which are moved in the threedimensional carved grooves of signage works, under the guidance of the NC programmed CAM system hereof.

[0140]
It would be within the scope and spirit of the present invention to also provide computerproduced sternboards for boats, yachts and the like, as well as computerproduced tombstones using the design and manufacturing method of the present invention. In the case of tombstones, the signboard can be a stone material such as granite, marble, sandstone or other suitable material, and the carving tool bit can be “diamond tipped” or made of material appropriate for carving stone under the guidance of the CAM system hereof.

[0141]
Using the method and apparatus of the present invention, names and patterns typically cut into tombstones by conventional waterjet cutting, sandblasting, chiseling and routing processes can be carved by way of an axially rotating cutting tool having at least threeprogrammable axes of simultaneous movement, under the guidance of the CAM system hereof.

[0142]
It would also be within the scope and spirit of the present invention to utilize one of laser and sandblasting principled devices as the carving tool of the method and apparatus of the present invention.

[0143]
In the case where laser devices are used, a laser beam of sufficient energy to burn away wood or other signboard constituting material can be controllably moved simultaneously in at least three programmable axes under the controlled guidance of the CAM system hereof. Such controlled movement of laser beams can remove signboard constituting material as to leave threedimensional carved patterns in the signboard, which correspond to the threedimensional surfaces of the threedimensional graphical model of the signage work to be carved therein. One example of laser cutting techniques is illustrated in U.S. Pat. No. 4,430,548 to Macken wherein laser apparatus and a process for cutting paper is disclosed.

[0144]
In the case where sandblasting devices are used, a focused pressurized stream of sand or like particles to blast away wood or other signboard constituting material, can be controllably moved simultaneously in at least three programmable axes under the controlled guidance of the CAM system hereof.

[0145]
However, in both the laser cutting and sandblasting processes described hereinabove, controlling the cutting depth of the laser beam in the case of the laser cutting process, and the sand stream in the case of the sandblasting process, is extremely difficult. In both cases, the post processor must take into consideration (i) the physical properties of the signboard material, and (ii) the precise energy (i.e., heat or momentum) of the cutting process utilized so that precise cutting depths can be obtained.

[0146]
Further modifications of the present invention herein disclosed will occur to persons skilled in the art to which the present invention pertains and all such modifications are deemed to be within the scope and spirit of the present invention defined by the appended claims.