IN A SYSTEM FOR MAKING WINDOW TREATMENTS

Field of Invention

[0001] This application claims priority to U.S. Utility Application No.

14/215,679, filed on March 17, 2014, and U.S. Provisional Application No.

61,790,169 filed on March 15, 2013, the entirety of which are hereby incorporated by reference.

[0002] This invention relates to window coverings, and more particularly to an improved method of fabricating and assembling window coverings of the type comprising expandable honeycomb or cellular window coverings formed of flexible fabric material. The disclosed method can also be used to form other types of window covering products that are, or can be, built up from joined and repeating elements, such as fabric-vane window shadings, pleated shades, Roman shades and roller shades.

Background of Invention

[0003] For purposes of the present description, a "shade" type of window covering is a type of area goods or panel whose final form is either (1) a single, continuous, integral piece of flexible fabric, without seams or joints in the fabric, as exemplified by the common roller shade, or (2) a series of identical or very similar strips of flexible fabric, directly contacting and connected to adjacent such strips by gluing, stitching, ultrasonic welding or the like, as exemplified by certain commercially available cellular honeycomb shades. In contrast, and also for present purposes, a "blind" is neither a type of area goods nor a panel, but instead comprises a series of separate, usually substantially rigid and opaque, elements (often called "slats" or "vanes") that are connected to one or more articulating members that permit the elements to be tilted through varying degrees of inclination to control the amount of light and visibility through the blind. Unlike a "shade," the elements of a "blind" are not directly joined (such as edge-to-edge) to the adjacent element in the series.

[0004] A third type of product, a "fabric-vane window shading," combines some of the physical characteristics of both a shade and a blind. An example of such a product is shown in Corey, U.S. Patent No. 6,024,819, wherein the product is described as a "fabric Venetian blind." The vanes may be formed of a relatively opaque fabric, rather than a rigid material as in the case of a conventional Venetian blind, and are

interconnected by full-area front and rear panels of a sheer or relatively translucent material. Thus, the resulting product is in the form of a panel comprising multiple stacked expandable cells, each of which is defined by upper and lower vanes and a portion of each of the front and rear panels. In that sense, a "fabric-vane window shading" constitutes a "shade" rather than a "blind" under the definitions used herein. It will therefore be referred to as a "fabric-vane window shading" in the present patent application.

[0005] Also, as used herein, "preform" refers to an elongated strip-like element or constituent part of a shade panel, which element may be flat or folded, single or multiple-piece, which has been cut to final (or final but for minor trimming) length for use in a window covering fabricated to fit a window of a particular size. This preform, or intermediary product, when joined directly along its longitudinal edges to identical or substantially identical adjacent preforms in a stack of such preforms, forms the panel portion of a window covering.

[0006] In the various embodiments disclosed herein, the preforms are typically described as having a "length" corresponding to the "width" of the window for which the completed window covering is ordered, because the preforms will be most commonly be oriented horizontally when installed in such window. Also, for the same reason, it is contemplated that the accumulation step where successive preforms are placed in side- by-side adjacency for compression and bonding, will usually be in a vertical "stack." However, it is to be understood that the process disclosed herein could also be used for making window coverings having vertically oriented elements or preforms, where the "length" of the preform will be oriented vertically, parallel to the "height" dimension of the window to be covered. Similarly, the "stacking" step could be implemented by bringing successive preforms into horizontal or inclined, rather than vertical, adjacency.

[0007] In all cases discussed herein, the fabric panel portion of the window covering is suitable for, and intended to be assembled to, appropriate hardware, such as top and bottom rails, control cords or wands, and the like, to facilitate installation and operation.

[0008] A popular type of window covering is a cellular window shade, made from either individual folded strips bonded to adjacent strips or a continuous transversely folded sheet of flexible web (fabric or film). The fold lines are set by a thermal curing process, and a stack of the folded strips or sheet is then bonded along adjacent parallel bond lines to create an expandable honeycomb structure in the form of a continuous column of joined cells.

[0009] U.S. Patent Nos. 4,450,027 and 4,603,072 to Colson describe one method of forming a "single-cell" honeycomb window covering, i.e., a product having a single column of joined expandable cells. According to that method, a continuous narrow strip of longitudinally moving flexible material is progressively folded into a flat, generally C- or U-shaped tube and then thermally treated to set the folds, while maintaining tension in the tube. Longitudinal lines of adhesive are then applied to the moving tube, and the tube is spirally wound onto a rotating frame having elongated flat portions, thereby creating a stack of cells of single-cell width that are adhered to each other by the previously applied adhesive. Straight sections of this bonded stack are then severed from the remainder of the wound tubing. This method is time-consuming and expensive, and generates non-flat portions of the winding that connect the adjacent flat portions of the rotating frame and that must be scrapped. The resulting bolt of expandable single-cell honeycomb fabric may be 12 or more feet wide and 40 feet long in its fully expanded condition. These bolts are then placed in inventory until needed to fill a customer order. In response to a specific customer-ordered window width and height, a stocked oversize bolt or panel of the ordered color and pattern is cut down to the required width and number of cells to provide the drop length needed for the height of the ordered windows, requiring skilled labor and inevitably resulting in substantial waste even if the remaining portion of a given bolt is returned to the inventory. Because future ordered window sizes cannot be predicted, except in a statistical way, operators must use complex and imperfect algorithms to minimize the residual waste as individual window- size sections are cut from the stocked blocks. Typical waste factors in converting blocks to window- size sections range from 25% in smaller shops to 15% in large-volume fabricators with steadier order streams.

[0010] A similar method is disclosed in Anderson, U.S. Patent No. 4,631,217, where the initially folded and creased material has a Z-shaped cross-section, with each winding of such strip forming the front of one cell and the rear of an adjacent cell after stacking and bonding. [0011] A later-developed method of forming expandable honeycomb fabric is disclosed in commonly-assigned U.S. Patent No. 5,193,601 to Corey et al. That method involves continuously feeding a broad web of flexible material, having a width that is at least as wide as the required width of the window covering, through a web-treating stage where desired coloring or patterning are printed onto the material. The web is then fed through appropriate drying or curing zones, and then between printing rollers that apply transverse parallel lines of adhesive at predetermined longitudinally spaced locations on the moving web. The web then passes through a station that partially cures the lines of adhesive to an intermediate, handlable state. The web next passes through a creasing and pleating apparatus that forms transverse fold lines at predetermined intervals and predetermined locations relative to the adhesive lines. A predetermined length of the web, now folded into a creased and generally serpentine shape, is then severed from the upstream portion of the web and collected and compressed into a stack, where the adhesive is further cured to permanently bond adjacent folds in a predetermined cellular pattern of double-cell width. This double-cell product can also be used to make single- cell panels by simply cutting off one of the columns (which, to reduce waste, is initially made narrower by shifting the adhesive line position), or by severing alternate internal ligaments between adjacent front and rear cells. While faster than Colson' s method, this method requires containment of large stacks of material for curing, usually done thermally by heating the entire stack and its containment structure. That heating method consumes excessive energy and time, and carries a risk of thermal distortion of the stack.

[0012] The initial web is typically formed into large bolts in the form of columns of expandable cells, typically 10 ten feet wide and 40 feet in fully expanded length. As in the case of the single-cell product described above, the inventorying, subsequent cutting labor and scrapped material is costly.

[0013] Another method of forming a generally cellular type of product is disclosed in commonly-assigned Corey, U.S. Patent No. 6,024,819. There, a fabric-vane window shading comprising sheer front and rear panels and relatively opaque fabric vanes is formed from an initial elongated, narrow, three-element strip having an opaque central portion secured by adhesive, stitching or other bonding technique along its two longitudinal edges to adjacent sheer strips. Of course, the three elements could be made from other materials, with the three components being the same or different. That three- element strip is then helically wound onto a supporting surface, with each successive winding only partially overlapping the immediately preceding winding (like slabs of bacon in a display pack) and bonded together along longitudinally extending bond lines. Finally, the resulting loop of layered material is cut open along a cutting line

perpendicular to the longitudinally extending bond lines and then stored in rolls that may be 10 feet wide and 13-14 feet long if unrolled to the full drop-length of the deployed condition. As in the case of the other disclosed methods, the cutting down of the initially formed cellular product into smaller pieces for specifically sized window coverings requires skilled labor and results in substantial amounts of scrapped material.

[0014] Assignee of this application, Comfortex Corporation, received U.S. Patent No. 8,465,617 entitled "Waste-Free Method of Making Window Treatments" on June 18, 2013 directed to an improved method of making window treatments (the '617 patent). The method described in the '617 involves cutting a plurality of identical-length preforms from a continuous strip of material and accumulating the preforms in a stack. As described at column 6, line 16 through column 8, line 4 of the '617 patent, the stack of preforms is accumulated in an accumulator chute 68 on an elevator bar 74. When the appropriate number of preforms associated with a single window covering is

accumulated in the accumulator chute 68, the stack of preforms is removed from the accumulator chute 68 and the elevator bar 74 is returned to its uppermost position.

[0015] The process of removing the stack of preforms from the accumulator chute 68 and returning the elevator bar 74 to its uppermost position as described in the '617 patent requires a certain amount of time. The '617 patent describes a method and apparatus that permits the accumulation of preforms for a subsequent window covering to continue uninterrupted while the current stack of preforms is removed from the accumulator chute 68. The inventors hereof have developed alternative, and perhaps more efficient, mechanisms and methods for facilitating the accumulation of preforms for a subsequent window covering in a system such as that described in the '617 patent.

Summary of Invention

[0016] A plurality of alternative methods and mechanisms for permitting the accumulation of preforms for subsequent window coverings to continue uninterrupted while the current stack of preforms is removed from an accumulator chute are described herein. Brief Description of the Drawings

[0017] Figure 1 A is an end view of a two-cell fragment of a single-cell type of expandable honeycomb window covering, made from the two preforms of the type shown in Figure IB, and shown in slightly expanded condition.

[0018] Figure IB is an end view of a cell preform adapted for stacking and assembly into a single-cell window covering as shown in Figure 1A.

[0019] Figure 2 is a simplified schematic perspective of strip-forming apparatus used for making single-cell preforms of the type shown in Figure IB in accordance with the present invention.

[0020] Figure 3 is a simplified schematic side view of a portion of a preform receiver/stacker apparatus for use in making cellular window coverings in accordance with the present invention.

[0021] Figure 4 is a fragmentary simplified schematic perspective view of a portion of the apparatus of Figure 3, additionally showing a portion of the cell preform accumulator chute .

[0022] Figure 5 is a simplified schematic end view of the apparatus of Figures 3 and 4.

[0023] Figure 6 is a simplified cross-sectional view of a radio frequency energy- emitting bonding press.

[0024] Figure 7A is an end view of a fragment of a double-cell type of expandable honeycomb window covering, made from two preforms of the type shown in Figure 7B, and shown in expanded condition.

[0025] Figure 7B is an end view of a cell preform adapted for stacking and assembly into a double-cell window covering as shown in Figure 7A.

[0026] Figure 8A is an end view of a fragment of a fabric-vane window shading type of window covering, made from two preforms of the type shown in Figure 8B, and shown in a partial light- admitting condition.

[0027] Figure 8B is an end view of a cell preform adapted for partially overlapping stacking and assembly into a fabric-vane window shading as shown in Figure 8A.

[0028] Figure 9A is a perspective view of a first alternative embodiment of an approach to ensure continued accumulation of preforms while a previous stack of preforms is unloaded from the elevator bar. [0029] Figure 9B is a perspective view of the embodiment shown in Figure 9A, illustrated in a second state.

[0030] Figure 10 is a top view of a second alternative embodiment of an approach to ensure continued accumulation of preforms while a previous stack of preforms is unloaded from the elevator bar.

[0031] Figure 11 is a top view of a third alternative embodiment of an approach to ensure continued accumulation of preforms while a pervious stack of preforms is unloaded from the elevator bar.

[0032] Figure 12 is a top view of fourth alternative embodiment of an approach to ensure continued accumulation of preforms while a pervious stack of preforms is unloaded from the elevator bar.

[0033] Figure 13 is a perspective view of a fifth alternative embodiment of an approach to ensure continued accumulation of preforms while a pervious stack of preforms is unloaded from the elevator bar.

[0034] Figure 13A is a perspective view of the fifth alternative embodiment illustrated in Figure 13, showing the accumulator in a second state.

[0035] Figure 14 is a perspective view of a sixth alternative embodiment of an approach to ensure continued accumulation of preforms while a pervious stack of preforms is unloaded from the elevator bar.

Detailed Description

[0036] Fig. 1 A illustrates an end view of a portion of a conventional single-cell honeycomb panel 10, such as widely used for shade-type window coverings. For illustration purposes, this portion comprises just two identical cells 12 bonded together by a pair of adhesive bead lines 14 that typically extend longitudinally along the full length of the elongated cells. One conventional way of forming cells 10 is to crease an initially flat elongated strip of fabric along two longitudinal crease lines 16 and then fold the outer portions inwardly toward the strip center line to form flaps 18, thus creating a "preform" 20 in the shape shown in Fig. IB. Next, two parallel lines or beads of adhesive 14 are applied adjacent to the edges of flaps 18, these adhesive lines preferably extending for the full length of the preform. A single-cell column or panel of honeycomb material may then be created by aligning, stacking and heat-curing the adhesive lines in a stack of the thus-formed preforms 20. [0037] A preferred strip-forming apparatus 22 is illustrated in the simplified schematic of Fig. 2. Fabric supply roll 26 and the other illustrated components are secured to one or more vertical support panels 24. In this illustrated embodiment, the supply roll carries uncolored, unpatterned, flat fabric strip 28. The width of strip 28 is selected to create the single-cell preform illustrated in Fig. IB, a preform that has no overlap when creased and folded. Alternatively, the strip width could be selected to provide an overlap of the preform edges if desired for the particular type of cell being formed. The fabric may be a woven textile made of cloth or polyester thread, or non- woven materials such as thin-film polyester. As will be described below, alternative processes could begin with a roll of pre-colored and patterned fabric, or the supply roll fabric could be pre-folded or a composite of multiple, joined, adjacent or superimposed, strips of identical or differing material, texture or opacity.

[0038] Strip 28 is pulled through apparatus 22, until it emerges as a fully formed and cut-to-length preform 30, by the combined control of supply reel motor 32, a pair of servo motor-driven nip or pulling rolls 34 and a pivoting, counterweighted, tension- leveling dancer 36, all conventional. From dancer 36, strip 28 passes through digital ink jet printer 38, where desired color and pattern is applied. Applicant has used a Fuji Film Dimatix printer, with associated proprietary software, for this purpose. The colored strip then moves into curing station 40, where the ink is set, preferably by high intensity UV radiation. Strip 28 then goes through creasing station 42 where, in the case of the single- cell preform 20 of Fig. IB, a pair of spring-loaded, sharp-edged creaser wheels, in conjunction with a backer roll, impresses two crease lines 16 into the strip near to the 1/4-width points in from each edge of the strip. This conventional type of creasing station is shown in schematic, simplified form in Fig. 2, and is more fully described and illustrated in the aforementioned Colson patent, 4,450,027.

[0039] After creasing, strip 28 is drawn through a conventional folding station

44, also shown in simplified and schematic form. This station may comprise a series of rollers of progressively changing shape or orientation and/or a channel which act to fold flaps 18 upwardly and then back down against the central portion of the strip, into the configuration shown in Fig. IB. Exemplary components of a conventional folding station are illustrated and described in the aforementioned Colson patent, 4,450,027. The folded strip then passes around a pair of heated drums 46 to set or iron in the folds, and then through an adhesive applicator station 48, also shown in schematic form. There, liquid bonding material, preferably a polyester hot melt adhesive, is supplied from a pump (not illustrated) and fed to nozzles that apply continuous, uniform, parallel adhesive beads 14 near to the flap edges. See Colson patent, 4,450,027, for further exemplary details. The adhesive only partially cures to a gel state while in strip former assembly 22, so that it will achieve a firm bond only after it is subsequently brought into contact with an adjacent preform and thereafter fully cured by the application of heat, as described below.

[0040] Finally, the folded but still continuous strip 28 is cut to a predetermined length by cut-off knife 50 and deposited onto receiver belt 52. The main process controller (not illustrated) utilizes data from the servo motors that drive nip rolls 34 to generate digital instructions to time the cutting stroke of knife 50 and thereby achieve the predetermined preform length. Preferably, belt 52 travels faster than the speed of strip 28 through strip former assembly 22, to assure that preform 30 is adequately spaced from following strip portions to avoid collisions and possible misalignment on belt 52.

[0041] An apparatus and method similar to that described immediately above is described in commonly assigned U.S. provisional applications 61/029,201 and

61/030,164, filed February 15, 2008 and February 20, 2008, respectively. There, individual cells are formed from a continuously-fed narrow strip of uncolored fabric, including the steps of coloring by digital ink jet printing, folding and cutting to predetermined lengths. However, in the process disclosed therein, the individual cells are not accumulated and bonded directly to each other to form an integrated array of cells, but instead form a blind-type of window covering having spaced-apart, separately expandable, cell-like vanes.

[0042] As shown in Figs. 3-5, cut-to-length preform 30 is conveyed along receiver/stacker assembly 54 by receiver belt 52 until it hits feed stop 56. The length of assembly 54 should be not less than the width of the greatest shade (i.e., the length of preforms 30) to be produced. Several sets of longitudinally- spaced idler rollers 58 function to create belt dip zones 60, where belt 52 dips below the horizontal plane of conveyance of preforms 30. These dip zones provide clearance for a series of preform stacker fingers 62 to push preforms 30 laterally off belt 52, without obstruction by or interference with the belt, once longitudinal movement of the preform has been stopped by feed stop 56. The preforms have sufficient rigidity to ride across dip zones 60 as they are conveyed toward stop 56. Because even short preforms need at least two stacker fingers to push them without misalignment of the preform, the pair of stacker fingers nearest stop 56 should be more closely spaced than the other pairs. Further, the spacing between successive pairs of pushers preferably increases uniformly from that end toward the cutter end, to assure optimum pusher position for a full range of preform lengths with the minimum number of pushers.

[0043] An optical interrupt (not shown) senses the presence of a newly arrived preform at stop 56, and signals stacker ball-screw drive 64 (see Fig. 4) to cause stacker bar 66 and its associated set of stacker fingers 62 to stroke transversely across receiver belt 52. This movement causes fingers 62 to engage the edge of the stopped preform and push it to accumulator chute 68, which is defined as the space between chute back plate 70 and chute front plate 72. The top edge of back plate 70 is slightly higher than the upper run of receiver belt 52 and the preform carried thereby, so that it acts as a locating stop to vertically align transversely moving preform 30 with previously accumulated preforms. Once the preform engages back plate 70 it will come to rest upon elevator bar 74, or upon the uppermost preform that was previously deposited there by stacker fingers 62. The longitudinal position of the accumulated preforms will also be identical, because each preform abutted stop 56 when it was engaged by the stacker fingers. That is, the respective opposite ends of the preforms in the stack will be laterally aligned with each other, forming opposite longitudinal edges of the array that are substantially

perpendicular to the length of the preforms.

[0044] While fingers 62 are still engaging the now stationary uppermost preform

30, tamper bar 76 is stroked downwardly by tamper cylinder 78 to initially compress the stack of preforms on elevator bar 74 and aid in preform-to-preform adhesion. As stacker bar 66 begins its return horizontal stroke over receiver belt 52, fingers 62 are raised relative to stacker bar 66 by stacker finger lift cylinders 80 so that the fingers will clear the next preform 30 that is moving along receiver belt 52 toward stop 56. In this way, the advance and return strokes of stacker bar 66 can proceed at a slower cycle time than the time elapsed while the following preform is advancing along receiver belt 52 toward stop 56, avoiding the need to reduce the speed of fabric strip 28 through strip forming assembly 22. At the conclusion of the return stroke of stacker bar 66, stacker fingers 62 are lowered by finger lift cylinders 80 to be in position to engage the following preform 30 when stacker bar 66 next strokes toward accumulator 68. In this regard, the distance from cut-off knife 50 to feed stop 56, along with the linear speeds of belt 52 and strip 28 through strip former 22, should be coordinated so that the leading edge of a given preform 30 has not advanced as far as the first (right-hand in Fig. 3) stacker finger 62 until the latter, is in its lowered position for engaging and laterally pushing the preceding preform 30, has completed its pushing stroke across belt 52.

[0045] As best shown in Figs. 4-5, the elevations of elevator bar 74 and the stack of preforms 30 resting thereon are controlled by elevator cylinder 82. Elevator bar 74 descends by a pre-determined amount for each preform deposited thereon, while maintaining the top of the preform stack just below the height of belt 52 to avoid obstructing the lateral transfer of a preform from belt 52 onto the accumulating stack. This accumulator arrangement permits a continuous infeed of newly cut preforms 30 from strip former assembly 22, but efficiency further requires that a complete stack of the predetermined number of preforms necessary to form a customer-ordered shade be immediately removed from accumulator chute 68 so that the preceding operations can continue uninterrupted. The overall system controller keeps track of the number of preforms that have been transferred from belt 52 to accumulator chute 68, so that a completed stack containing the required number of preforms for the ordered window covering will be automatically and timely removed from the chute for further processing.

[0046] That removal step is performed by the apparatus illustrated in Fig. 5, which is a view looking upstream along the length of receiver belt 52 from a point downstream from the downstream end of belt 52 (in other words, from the left end of Figs. 3-4 toward the right end thereof). The position of elevator cylinder 82 and the length of its stroke are selected so that the top of a completed stack 90 of preforms on elevator bar 74 can clear the bottom of chute back plate 70, enabling the stack to thereafter be moved to the right (as viewed in Fig. 5) and onto transfer belt 84. When stack 90 in accumulator chute 68 is completed, elevator cylinder 82 retracts elevator bar 74 until the topmost preform on the stack is below the bottom of chute back plate 70. Transfer cylinder 86 then strokes transfer bar 88 to the right, engaging and pushing completed preform stack 90 onto transfer belt 84 and against transfer stop wall 92.

Transfer belt 84 may operate continuously if it has a smooth surface to permit it to freely slide beneath the stationary bottommost preform while the stack is held against stop plate 92 by transfer bar 88. Subsequent retraction of bar 88 would then free the stack to be conveyed by belt 84 to the adhesive-curing station (not shown in Fig. 5). Alternatively, belt 84 can be controlled to operate only after completed stack 90 has been deposited thereon by transfer bar 88. Vertically oriented rollers can be provided to confine and guide stack 90 as transfer belt 84 carries it to the curing station.

[0047] Transfer belt 84 conveys preform stack 90 to curing station 94, schematically illustrated in Fig. 6. The transfer belt serves as a wait-state holder for a queue of stacks. Therefore, its length may be selected as required, depending on the curing speed of the following heating and adhesive-curing step compared to the previously described stacking speed. The queue may be held on the belt, with the belt' s smooth surface sliding under the queued stacks as they pile up gently against a stop at the downstream end of transfer belt 84 and until an operator removes a stack 90 from the belt and places it into heating press or platen 96. A radio frequency (RF) type of heating press is preferred, for reasons that will be explained below. Use of this form of heating, to preferentially heat the adhesive rather than the fabric, is disclosed in a commonly assigned published application, US 2007/0251637, published on November 1, 2007.

[0048] Press 96 is preferably dimensioned to receive the largest contemplated stack size. The press 96 includes base 98 and lid 100 interconnected at hinge or hinges 102. A compression ram 104 is disposed at one end of the stack to assure alignment of all preforms 30 and to apply pressure to stack 90 and its adhesive lines. Stack 90 is placed in press 96, lid 100 closed and locked, and compression ram 104 advanced to compress the stack so that full contact is assured between the surfaces to be bonded by heated adhesive lines 14. Thereafter, an RF field is energized by generator 106, powered by an electrical input 108. Application of the resulting RF electromagnetic field by voltages on the conductive electrode platens 110, 112 of the curing apparatus 96 heats the adhesive lines (e.g., adhesive lines or beads 14 in Figs. 1A and IB) to trigger activation and curing of the adhesive, thereby bonding adjacent preforms together wherever adhesive lines are present between them.

[0049] To permit the accumulation of a new stack to continue in accumulator chute 68 while elevator bar 74 is lowering a completed stack and returning to its uppermost position, various approaches may be employed. The '617 patent described in the Background of this application describes the use of a series of temporary accumulator fingers (not illustrated) in the form of narrow, flat, horizontal blades that would slide horizontally (from right to left in Fig. 5) through slots in back chute plate 70. The fingers would receive the first few preforms of the next stack until elevator bar 74 has risen to its uppermost position, at which point the temporary accumulator fingers would be withdrawn, depositing the accumulated preforms onto elevator bar 74.

Alternatives to the use of such temporary accumulator fingers are described below in detail.

A. Embodiment #1 - Diverter

[0050] A first alternative approach to ensure continued accumulation of preforms while a previous stack of preforms is unloaded is described in connection with Figures 9 A and 9B, both of which illustrate the inclusion of a diverter mechanism 200 in the system described above in connection with Figures 2-6 (where the same reference numbers relate to the same elements). In general, the diverter 200 is positioned between cut-off knife 50 and receiver belt 52 and configured to selectively divert the travel path of material strip 28 so as prevent it from passing to receiver belt 52 for a period of time, typically the time period while the elevator bar 74 is lowered and until it returns to its uppermost position. The diverter 200 may be a selectively insertable fence, like that shown as element 200 in Figures 9 A and 9B, which may be controlled mechanically and/or electrically in conventional manners as known by persons skilled in the art.

Alternatively, the diverter 200 may be a vacuum suction duct configured to pull the material strip 28 away from its normal travel path. Figure 9A illustrates the diverter 200 in a first position, outside the normal path of material strip 28, and Figure 9B illustrates the diverter 200 in a second position, in the normal path of material strip 28 so as to divert material strip 28. During the time that the material strip 28 is being diverted, it may be deposited into a waste container 210, such as that shown as element 210 in Figures 9 A and 9B. The diverter 200 may be actuated after the cutting and separation of the last preform 30 of the current preform stack (corresponding to a single window covering). Once actuated (shown in Figure 9B), the diverter 200 redirects the oncoming strip of material into waste receiver 210 until the accumulator chute 68 is emptied and the elevator bar 74 has risen to its uppermost position. Then, the cut-off knife 50 is activated again, severing the waste strip from the beginning of a new stack of preforms. The diverter 200 is then de-actuated, which causes the preforms 30 (for the subsequent window covering) to flow onto receiver belt 52 again and accumulate in accumulator chute 68 and on elevator bar 74. Embodiment #2 - Multiple Movable Belt Chute and Elevator Bar Assemblies ("Receiver Assemblies")

[0051] A second alternative approach to ensure continued accumulation of preforms while a previous stack of preforms is unloaded is described in connection with Figure 10, which illustrates the inclusion of a second substantially identical belt 52', chute 68', and elevator bar 74' assembly (collectively, a "Receiver Assembly") in the system described above in connection with Figures 2-6 (where the same reference numbers relate to the same elements). The second Receiver Assembly (52', 68', 74') is positioned beside the first Receiver Assembly (52, 68, 74). The two Receiver

Assemblies are mounted on a lateral slide 73. The slide 73 is equipped with an actuator 71 that aligns the Receiver Assemblies (one at a time) with the path of strip 28 and preforms 30 approaching from the cut-off knife 50 in response to electronic controls. When a first stack of preforms 30 has formed on the first elevator bar 74, the actuator switches state, pushing the first Receiver Assembly (52, 68, 74) aside and bringing the second Receiver Assembly (52', 68', 74') into alignment with the oncoming strip 28. While a second stack of preforms is accumulating on the second chute 68' & elevator 74' assembly, the first stack of preforms 30 is removed from the first elevator bar 74 and the first elevator bar 74 is returned to its uppermost position. Once the second stack of preforms 30 is fully accumulated on the second elevator bar 74', the actuator reverses state and returns the first belt 52 to alignment with the oncoming strip. While the first elevator bar 74 is accumulating another stack of preforms, the second elevator bar 74' is emptied of the second accumulated stack of preforms 30 and is returned to its uppermost position. This sequence is repeated to produce a continuous series of stacked preforms.

[0052] This particular embodiment may be modified by implementing multiple

(two or more) substantially identical Receiver Assemblies that are connected by a transverse belt or other carrier (e.g., a chain) of known type, which is used to

alternatively align any one of the multiple Receiver Assemblies in the path of the strip 28 and preforms 30. The carrier may be equipped with an actuator that sequentially aligns each of the belts 52 with the path of the strip 28 and preforms 30 approaching from the cut-off knife 50. When a first stack of preforms 30 has formed on a first elevator bar 74, the actuator advances the carrier, pushing the first Receiver Assembly aside and bringing a second belt 52' into alignment with the oncoming strip. While a subsequent stack of preforms 30 is accumulating, the first formed stack is removed and the first elevator bar 74 returned to its uppermost position. Once the second stack of preforms 30 is fully accumulated on the second elevator bar 74', the actuator again advances the carrier and, pushing the second Receiver Assembly aside and bringing a subsequent chute 52" into alignment with the oncoming strip 28. While the subsequent elevator bar 74' ' is accumulating another stack of preforms, the second elevator bar 74' is emptied of the second accumulated stack of preforms 30 and returned to its uppermost position. This sequence is repeated to produce a continuous series of stacked preforms.

[0053] Another modification of this embodiment could include employing just the chutes (68, 68') and elevator bars (74, 74') as the Receiving Assembly and maintaining a single stationary belt 52. That is, it is possible to maintain a single belt 52 for transporting the preforms from the cutter 50, which pushes each of the preforms directly onto the chutes (68, 68') and elevator bars (74, 74') without the use of fingers 62. In this alternative embodiment, the preforms are pushed into the first chute 68 and elevator bar 74 until a first stack is accumulated and then the second chute 68' and elevator bar 74' are moved into alignment with the single belt 52, after which preforms are pushed onto the second chute 68' and elevator bar 74' until a second stack of preforms are accumulated.

Embodiment #3 - Multiple Stationary Chute and Elevator Assemblies

[0054] A third alternative approach to ensure continued accumulation of preforms while a previous stack of preforms is unloaded is described in connection with Figure 11, which illustrates a second stationary chute 68' and elevator bar 74' combination in the system described above in connection with Figures 2-6 (where the same reference numbers relate to the same elements). Unlike the system described in connection with Embodiment #2, the first chute 68 and elevator bar 74 assembly and the second chute 68' and elevator bar 74 assembly are stationary and a mechanism is used to selectively stack the preforms 30 in one or the other. In one embodiment (shown in Figure 11), the two chute & elevator assemblies are positioned parallel to each other on opposite sides of belt 52. Bi-directional fingers 62' are configured similar to fingers 62 (shown in Figure 3), except that they configured to be alternatively actuated toward the first chute and elevator assembly 68 and 74 and the second chute and elevator assembly 68' and 74' . While accumulating a stack of preforms for a first window covering, fingers 62' operate to push each individual preform onto the first chute 68. When the first stack of preforms is complete, the chute and elevator assembly 68 and 74 lower and the fingers 68' begin to push oncoming preforms onto the second chute and elevator assembly 68' and 74'. While a second stack of preforms 30 is accumulating on the second chute and elevator assembly 68' and 74', the first formed stack of preforms is removed from the first chute 68 and the first elevator 74 is returned to its uppermost position. Once the second stack is fully accumulated on the second elevator bar 74', the second elevator bar 74' lowers and the fingers 62' push preforms 30 to the first chute 68. While the first elevator bar 74 is accumulating another stack of preforms 30, the second elevator bar 74' is emptied of the second accumulated stack of preforms 30 and is returned to its uppermost position. This sequence is repeated to produce a continuous series of stacked preforms 30.

[0055] Alternatively to the fingers 62', the system may instead be equipped with a pick-and-place device of well-known type (e.g., vacuum lifters on servo-driven XYZ slides) to capture and deliver incoming preforms 30 into one of the elevator bars 74 or 74'. When a first stack of preforms 30 has been formed on a first elevator bar 74, the pick-and-place device starts placing the incoming preforms 30 onto a second elevator bar 74'. While a second stack of preforms 30 is accumulating there, the first formed stack is removed and the first elevator bar 74 returned to its uppermost position. Once the second stack is fully accumulated on the second elevator bar 74', the pick-and-place device starts placing the incoming preforms 30 onto another of the plurality of elevator bars 74, including possibly the first elevator bar (which has since risen to its uppermost position). This sequence is repeated to produce a continuous series of stacked preforms 30. The number of elevator bars 74 is chosen to allow sufficient time for unloading each elevator bar 74 before it is required again for a subsequent stack of preforms 30.

[0056] Another modification of this embodiment could include employing just the chutes (68, 68') and elevator bars (74, 74') as the Receiving Assembly. That is, it is possible to transport the preforms from the cutter 50, by pushing each of the preforms directly onto the chutes (68, 68') and elevator bars (74, 74') without the use of fingers 62 or pick-and-place device. In this alternative embodiment, the preforms are pushed into the first chute 68 and elevator bar 74 until a first stack is accumulated and then a diverter (not shown) redirects the preforms into the second chute 68' and elevator bar 74', after which preforms are pushed onto the second chute 68' and elevator bar 74' until a second stack of preforms are accumulated. Embodiment #4 - Multiple Sequential Chute and Elevator Assemblies

[0057] A fourth alternative approach to ensure continued accumulation of preforms while a previous stack of preforms is unloaded is described in connection with Figure 12, which illustrates a second stationary chute 68' and elevator bar 74' assembly in the system described above in connection with Figures 2-6 (where the same reference numbers relate to the same elements). Second substantially identical elevator bar 74' is positioned in line after the first elevator bar 74 in chute 68. The two elevator assemblies are each equipped with end stops 56 and 56', respectively. When a first stack of preforms 30 is accumulating, the nearer stop 56 is withdrawn and the farther stop 56' is in place, so that the preforms 30 accumulate on the farther elevator bar 74'. When the first stack of preforms has completely formed on the farther elevator bar 74', the nearer stop 56 is switched into position, so that subsequent preforms 30 are halted and accumulated on the nearer elevator bar 74. During that subsequent accumulation, the first-formed stack on farther elevator bar 74' is removed and that elevator bar 74 is returned to its uppermost position. Once the second stack of preforms 30 is fully accumulated on the nearer elevator bar 74, the nearer stop 56 is withdrawn, and subsequent preforms 30 pass over the nearer receiver belt 52 and accumulate against farther stop 56' and on farther elevator bar 74' . While the farther elevator 74' is accumulating another stack of preforms 30, the nearer elevator 74 is emptied of its accumulated stack of preforms 30 and returned to its uppermost position. This sequence is repeated to produce a continuous series of stacked and removed preforms 30.

[0058] Embodiment #5 - Expandable Accumulator

[0059] A fifth alternative approach to ensure continued accumulation of preforms while a previous stack of preforms is unloaded is described in connection with Figures 13 and 13 A, which illustrate an expandable accumulator in the system described above in connection with Figures 2-6 (where the same reference numbers relate to the same elements). An expandable accumulator (comprising rollers 34 that selectively slide in slots 35) can be provided after the coloring, folding, and gluing steps, to maintain their continuous operation, but before the cutting step. Figure 13 illustrates the expandable accumulator in a first state during which strip 28 is flowing through the system and preforms 30 are being generated. Figure 13A illustrates the expandable accumulator in a second state during which the output of strip 28 is halted by gripper 51 and the accumulator slack in the strip 28 is taken up by the expanded accumulator (rollers 34 in slots 35). A gripping mechanism 51 may be provided near the cutter 50, to temporarily halt the output of strip material 28. Gripper mechanism 51 descends and grips the strip material 28 when actuated. During such halt period, a series of separable wheels 34 over which is threaded the strip 28 is moved apart in corresponding slots 35 to increase the length of strip engaged there and absorbing the continuous flow despite the halt downstream. The accumulator expands until elevator bar 74 has risen to its uppermost position. Then, the gripper 51 is withdrawn, and the outflow of strip restarts, with the cutter again cutting the strip 28 into preforms 30, and depositing the accumulated preforms 30 onto elevator bar 74.

[0060] Embodiment #6 - Gripper

[0061] A sixth alternative approach to ensure continued accumulation of preforms while a previous stack of preforms is unloaded is described in connection with Figure 14, which illustrates the incorporation of a gripper mechanism 71 in the system described above in connection with Figures 2-6 (where the same reference numbers relate to the same elements). A stack-removing gripper 71 is provided at the far end of the elevator bar 74. When a stack of preforms 30 is complete, the gripper 71 is actuated and closes on the far end of the stack and extracts the stack from the elevator bar 74 by accelerated pulling of the entire stack away from the next incoming perform 30, while the elevator bar 74 is rising back to its uppermost position. The next preform 30 falls freely onto the emptied, rising elevator bar 74 (which is never more than a few inches below its uppermost position, due to the compactness of stacks relative to their expanded, window-covering heights).

[0062] Any of the above-described alternatives may be advantageously used to ensure the continuous accumulation of consecutive stacks of preforms.

[0063] Adhesives that are advantageously used with RF- field curing must be thermally curable and sensitive to excitation and self-heating or curing when exposed to RF electromagnetic fields. They should include compounds such as polyester monomers, metal salts, or nylon that readily absorb energy from such fields.

[0064] In an exemplary heating press 96, generator 106 is a 25 KW power supply that operates at 17MHz. A frequency of 27.12 MHz is ideal for coupling to the adhesive, but field efficiency and stability is enhanced at lower frequencies, and coupling is still adequate. At that frequency, the fabric portion of the assembled preforms has significantly less energy absorption than the adhesive, minimizing the risk of thermal distortion of delicate fabrics. The temperatures of upper electrode 110 and lower electrode 112 are controlled to a constant temperature of 65 degrees Fahrenheit by chilled and heated water (not shown). The temperature is raised and lowered with changes in ambient temperature. The power and frequency are continually adjusted to compensate for load changes during curing. Compression ram 104 and upper electrode 110 pressures are deliverable pneumatically in two stages between 20 and 50 pounds per square inch (PSI).

[0065] In one exemplary process, stack 90 is placed in press 96 and onto lower electrode 112. Lid and upper electrode 110 are lowered to a predetermined height in contact with the stack. The stack is initially compressed by pneumatic ram 104, at which time the RF field is activated at 3.5 amps to preheat adhesive lines 14 without forcing stack 90 out of stacked alignment. After a predetermined time, the adhesive lines have been softened, the stack is then further compressed, and the RF field is reduced to 2.75 amps to complete the bonding. After a second predetermined period of time, the RF field is terminated and the stack remains under pressure for an additional predetermined cooling period to cool in position, setting the bonds. After the cooling cycle, upper lid 100 and upper electrode 110 are raised and the fully bonded and cured stack 90 is removed from press 96. The bonded array or panel is then ready for assembly to secondary components, such as top and bottom rails and control cords or wands, in conventional manner.

[0066] A final trimming step may be necessary if the ends of the individual preforms in the bonded stack are not perfectly aligned. For that purpose, the process may be set up so that preforms 30, as cut-to-length by cut-off knife 50, are very slightly over-length. It is contemplated, however, that this trim loss would be minimal, as alignment errors in stacking are typically less than 1/16 ^ώ of an inch on each end of the preform. In a typical shade width of four feet, this 1/8 ^ώ of an inch of trim loss represents less than 0.3% of material waste, an insubstantial amount.

[0067] The presently disclosed equipment and process could be modified without departing from some of the important aspects of the disclosed method. For example, the strip on fabric supply roll 26 could be pre-folded into the shape of the preform before it is wound onto that roll, thereby eliminating the creasing, folding and fold-setting heating steps from taking place within strip forming assembly 22. Other modifications include use of other types of digital printing devices, such as dye sublimation or wax transfer; or non-digital printing (such as by spray or transfer rolls) or even elimination of the coloring step by using pre-colored fabric on the supply roll; or application of the adhesive lines after rather than before the preforms are cut to length, or as interrupted, stitch-like lines; or producing pre-cut preforms in several standard lengths (as for common window widths), perhaps combined with post-manufacture trimming to final window covering-size width (i.e., preform length), with or without bonding during initial manufacture; or producing bonded preform assemblies of a standard number of cells corresponding to the desired drop length for windows of a standard height, followed by cutting to final window covering width only upon receipt of a customer order; or use of other types of heating to cure the adhesive. In-line punching of clearance holes for control cords could also be accomplished at an appropriate station within strip forming assembly 22, before strip 28 is cut to length.

[0068] It is also contemplated that the length of the initially cut-to-length preform could be selected to correspond to the combined length of two or more preforms, of either identical or different lengths. For example, if a customer were to order multiple window coverings of identical style, color and height, but of different widths (e.g., three and four feet), the initial preform could be cut to their combined length (seven feet in the example). Following accumulation and bonding of that combined-length array (to assure positional stability of the preforms in the array to be cut), the bonded array could then be cut again to divide that array into the two (or more) specified window covering widths.

[0069] Strip forming assembly 22 can be readily modified to form other types of known window covering panels, such double-cell honeycomb, pleated shades, non- pleated or non-creased shades such as billowed or open flap Roman shades, conventional roller shades formed of horizontal strips of different materials or colors or patterns, or fabric-vane window shadings (in both horizontal or vertical orientation), each of which is or could be comprised of multiple preform elements directly joined to adjacent such elements. The conversion steps may include one or more of the following: a change in the material or width of the fabric on supply roll 26, a change in number or lateral position of the creasing wheels at creasing station 42, a change in the number or position of adhesive applicators at station 48, and a change in the out feed apparatus for accumulating preforms that are not to be stacked vertically. [0070] Figs. 7 and 8 show examples of differently shaped preforms used to form other types of window covering panels. Fig. 7 A shows a three-cell fragment of a conventional double-cell window covering panel 114, fabricated from two identical preforms 116a and 116b (one of which is shown in Fig. 7B) that have been bonded together. Each preform has two creases 120 and three longitudinally extending adhesive lines, 122, 124 and 126. The creases serve as crisp hinge points that, after folding and heat-setting of the folds in strip former assembly 22, create preform 116 having central portion 128, long flap 130 and short flap 132. Preferably, after creases 120 are applied and the two flaps folded into the configuration shown in Fig. 7B, adhesive line 124 is applied to ultimately secure flap 130 to central portion 128, thereby defining a first closed cell. Subsequently, before preform exits strip former assembly 22, adhesive lines 122 and 126 are applied. Thereafter, when preforms 116 have been cut to length and stacked (as previously described with respect to Figs. 3-4), adhesive lines 122b and 126b will bond preforms 116a and 116b together, as shown in Fig. 7A. Alternatively, preform 115 could be formed in a C- shape rather than the Z- shape of Figure 7B, by folding short flap 132 upwardly rather than downwardly, and shifting adhesive line 126 to the upper surface of flap 132 adjacent its free end. In that position, adhesive line 126 would contact the upper adjacent preform rather than the lower adjacent preform.

[0071] Fig. 8A illustrates a two-preform fragment of fabric-vane window shading 134 made by bonding together adjacent and partially overlapping identical three- component preforms 136a and 136b. Other multi-component preforms that may be used to make fabric-vane window shadings are disclosed in commonly assigned U.S. Patent Nos. 6,024,819 to Corey and 6,302,982 to Corey and Marusak. The presently disclosed method of forming and assembling window coverings could also be used to create fabric - vane window shadings having configurations disclosed in those earlier patents.

Referring to Figs. 8 A and 8B, by way of example, the forming process would begin with a three-component strip consisting of at least two dissimilar fabrics whose adjoining longitudinal edges have been connected by gluing, ultrasonic welding, thermal bonding or stitching. Ultrasonic welding is preferred, because it is speedy and permits precise location of adjoining edges. Outer strips 138, 140 are formed of relatively translucent or sheer material, and may be formed of the same or different fabrics. Central portion 142 is formed of a relatively opaque material, opacified by use of a more densely woven material, or by coating or laminating or by insertion of opaque inserts into an integrally formed pocket. Alternatively, central portion 142 could be formed from the same uncolored fabric as outer strips 138, 140, and then digitally colored by the ink jet printer 38 to provide the desired contrast. Preferably, the three-component strip would be wound in a pre-joined state on supply reel 26, but the joining of the adjacent components 138, 140, 142 of the three-element strip could be accomplished in a preliminary, but still continuous, extension of the disclosed strip former assembly 22, or it could be achieved by folding rather than by ultrasonic joining. As shown in Figs. 8A and 8B, adhesive lines 144 and 146 are applied to preform 136 within strip former 22, but without creasing or folding steps in the disclosed fabric-vane window shadings embodiment.

[0072] As shown in Fig. 8 A, formation of a fabric-vane window shading requires laterally staggered, only partially overlapping, positioning of successive preforms 136a, 136b, similar to the way bacon strips are placed in a display pack.

Successive preforms would, as in the case of the other disclosed preform configurations, still have their ends in lateral registry with each other. That arrangement is required so that successive sheer strips 138a, 138b, etc., will form adjacent segments of the front or rear sheer panel of the completed fabric-vane window shading, while successive sheer strips 140a, 140b, etc., will form adjacent segments of the other sheer panel. As is common with this type of product, the angular position of opaque vanes 142 between the parallel front and rear sheer panels is manually controlled by inducing relative movement between the two sheer panels. To accomplish that staggered rather than fully overlapped and stacked configuration, receiver/stacker assembly 54 would need to be modified so that the cut preform elements are pushed from receiver belt 52 onto a transversely moving or indexing belt rather, than into a vertical accumulator chute 68. The resulting product could be used as a vertical sheer or fabric-vane window shading, with the vanes oriented vertically, rather than as a fabric-vane window shading having horizontally oriented vanes.

[0073] Those skilled in the art will recognize that still other configuration of preforms may be created using the apparatus and method disclosed herein to form repeating and directly joined elements of other types of window coverings. Appropriate modifications of creasing wheel position, folding station configuration and adhesive applicator position would be required.

[0074] One benefit of the above described RF energy-curing process is the application to multiple linear adhesive features that are neither 'parallel' (i.e., reaching from one electrode to the other) nor 'perpendicular' (i.e., presenting a broad flat target normal to the field). In some instances, called 'stray field' heating, the adhesive to be heated cannot be arranged either perpendicularly or parallel to the electrode plates. In the described process, however, the adjacent substrate material is not RF-conductive and so experiences little absorption of the RF energy from stray fields. The fabric material supplied from reel 26 may be formed from woven fabric, non- woven fabric, polyester, or the like. The described process relies on the uniform placement of discontinuous absorbent zones (adhesive lines 14) to produce uniform absorption and heating of those zones. Otherwise, the field stability and heating uniformity becomes unsustainable.

[0075] Another benefit is the adaptation of an RF press 96 to a flexible substrate.

The RF curing of a complex, flexible, expandable, product, as described in the above- cited commonly assigned published application, US 2007/0251637, is believed to be unique and offers advantages over the prior art methods of bonding delicate window covering materials.

[0076] As will be clear to one skilled in the art, the described embodiments and methods, though having the particular advantages of compactness and convenience, are not the only methods or arrangements contemplated. Some exemplary variants include: a) material to be treated and bonded can be fed through the RF field in a continuous stream, rather than by batches; b) material blocks to be bonded can be fed through a smaller field area, curing from one end to the other sequentially, rather than the whole block at once; and c) any combination of frequencies and materials receptive thereto could be substituted for the chosen RF and adhesives.

[0077] The precise application of activation energy to the adhesive rather than the bulk stack of material has many advantages including: a) reduced total energy usage; b) reduced cycle time without waiting for heating and cooling the bulk material or containments; c) reduced handling of goods by in-line treatment rather than large oven- run batches; d) reduced thermal distortions and discolorations due to uneven heating of stack materials; e) precise and uniform heating of adhesive to assure uniform and complete bonding of adjacent layers without bleed-through to farther layers; f) usability with stack materials that are not amenable to thermal or other adhesive curing cycles in bulk; and g) improved regularity of pleat alignment and adhesive line positioning by reduced clamping and thermal loads during cure. [0078] The use of a digitally-controlled ink jet printer provides great flexibility in not only the color and pattern of inks applied to the supplied fabric, but also variation in color or pattern along the length of the strip being fed through the printer. That is, nonuniform coloring or patterning can be applied, not only along the length of what will (after cutting) be an individual preform, but also each preform of a given window covering need not be identical in color or pattern to others in a given stack and window covering. Thus, when differently colored or patterned successive preforms of a given window covering are properly collated, a large pattern, border or image can be created that requires integration of multiple preforms of the window covering for its complete rendition, with each preform only supplying a portion of the entire desired design.

[0079] The process disclosed above provides virtually total elimination of waste material formerly inherent in the cutting down of large bolts of fully formed expandable goods to customer-ordered window covering sizes. Also eliminated are the additional costs of handling such materials during and following fabrication of the bolts, as well as the storage space and costs of storing large bolts and remnants of each of the various colors and fabrics within a manufacturer's catalog of available products. This process also permits faster conversion of customer orders to deliverable goods, with fewer order entry and handling errors. To that end, it is contemplated that customer orders, for a specified window covering type, including style, window height and width, choice of fabric, color and pattern, could be transmitted by the Internet or other electronic communications medium from a retail outlet or interior designer' s studio to the manufacturer, where appropriate software and look-up tables could convert the customer's specifications into digital instructions for the system disclosed herein. For example, as is known in the art, the specified vertical height or "drop height" of a cellular type window covering can be readily converted to the required number of cells or preforms by reference to a look-up table.

[0080] The preceding description has been presented only to illustrate and describe exemplary embodiments of the methods and systems of the present invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. The invention may be practiced otherwise than is specifically explained and illustrated, without departing from its spirit or scope. The scope of the invention is limited solely by the following claims.