Printing multi-channel image on web receiver

A multi-channel image is printed on a web receiver by a plurality of printing modules. The receiver is entrained around a take-up roll on a movable transport. During printing, the transport moves past the printing modules while the take-up roll holds the receiver in position with respect to the transport, and then the transport comes to a stop and the take-up roll draws the receiver across the transport. A cutter downstream of the take-up roll cuts off the printed portion of the web receiver to provide a printed sheet.

FIELD OF THE INVENTION

This invention relates to printing images on continuous-web receivers.

BACKGROUND OF THE INVENTION

Color and other multi-channel images can be printed using ink jet printers, multicolor transferable toner printers, heat sensitive coated paper printers, thermal dye transfer printers, and other types of printers. Many mass-market retail establishments have user-friendly kiosks at which shoppers make color prints. Because the kiosks use large amounts of paper, the images can be printed on a continuous web of paper, often supplied in roll form and fed from a feed roll to the printhead that applies the image to the receiver. The images are later separated from each other and from the web by a suitable cutter or knife.

It is desirable when roll-feeding to pull the web past the printhead. This provides positive control of the web as it passes the printhead. In various schemes, the printhead forms part of the pulling apparatus, as in U.S. Pat. No. 5,441,353 to Kim. In other schemes, a separate pulling mechanism beyond the printhead is used, as in U.S. Pat. No. 5,021,804 to Nozawa et al. However, printing technologies such as inkjet printing use non-contact printheads, so the printhead cannot form part of the pulling apparatus. Moreover, using a pulling mechanism downstream of the printhead results in the receiver between the printhead and the pulling mechanism being unprinted and discarded, increasing waste and print cost.

Other schemes push the web past the printhead. Examples of such schemes are JP Publication No. H05-147284 (1993) by Kikumura et al. and JP Publication No. 2004-217342 by Iemura et al. However, these schemes do not provide positive control of the receiver until it engages a pulling member sometime after printing begins. This can result in variations in the spacing between the receiver and a non-contact printhead in the leading portion of the image, changing image attributes. These changes can produce a visibly-objectionable difference between the portion of the image pushed past the printhead and the portion pulled past. Pushing the web past the printhead over its entire length exacerbates these problems and can lead to receiver buckle, possibly contacting a non-contact printhead and damaging it (a “head strike”).

There is a continuing need, therefore, for a way of printing images on a continuous web with reduced waste of paper while maintaining consistent image quality.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided apparatus for printing a multi-channel image on a web receiver, comprising:

a) a plurality of printing modules arranged in sequence along a feed path of the receiver and spaced apart from the feed path, each adapted to produce on the receiver a separation image corresponding to one channel of the multi-channel image;

b) a movable transport for the web receiver, the transport including a take-up roll around which the receiver is entrained and a cutter arranged downstream of the take-up roll for selectively cutting the web receiver, wherein:the transport is operative in a first state to traverse from the leading printing module to the trailing printing module;the take-up roll is operative in the first state to retain the receiver in position with respect to the transport; andthe take-up roll is operative in a second state to draw the receiver across the transport; and

c) a controller adapted to perform the following steps in order:operate the transport and take-up roll in the first state and activate one or more of the printing modules in sequence to print a first portion of the image;once the transport traverses to bring the web receiver into operative arrangement with the plurality of printing modules, operate the take-up roll in the second state and activate one or more of the printing modules to print a second portion of the image; andcause the cutter to cut the web receiver to provide a cut sheet bearing the printed image.

According to another aspect of the present invention, there is provided a method of producing a print of a multi-channel image on a web receiver, comprising:

entraining the web receiver around a take-up roll on a transport;

traversing the transport past a plurality of non-contact printing modules and depositing respective separation images on the receiver by activating the printing modules as they are brought into operative association with the receiver on the transport, so that a first portion of the image is printed; and

drawing the receiver past the printing modules using the take-up roll and activating the printing modules to deposit respective separation images on the receiver, so that a second portion of the image is printed.

According to another aspect of the present invention, there is provided a method of producing a print of a multi-channel image on a web receiver, comprising:

entraining the web receiver around a take-up roll on a transport;

traversing the transport past a plurality of non-contact printing modules and depositing respective separation images on the receiver by activating the printing modules as they are brought into operative association with the receiver on the transport, so that a first portion of the image is printed;

drawing the receiver past the printing modules using the take-up roll and activating the printing modules to deposit respective separation images on the receiver, so that a second portion of the image is printed, wherein a selected one of the printing modules deposits a first-layer separation image on a selected area of the receiver in the first or second portion;

repositioning the receiver by returning the transport or rewinding the receiver, or both, so that the selected area of the receiver is brought into operative association with the selected printing module; and

moving the receiver by traversing the transport or drawing the receiver, or both, while activating the selected printing module to deposit a second-layer separation image on the selected area of the receiver.

An advantage of this invention is that it provides reduced waste of receiver material in a non-contact, continuous-web printer. It maintains positive tension on the paper during printing, improving image quality. It is not limited in the total length of sheet that can be printed, and it is not limited to certain predetermined sizes of cut sheet. The receiver only moves in a single direction during printing, which can improve throughput. The movable transport can overcome the inertia of the supply of web receiver, permitting the take-up roll to be driven by a smaller, more responsive motor, and permitting the take-up roll to have a lower diameter than would be required if the take-up roll had to overcome the web inertia. Using a smaller-diameter take-up roll reduces the amount of receiver wasted as a leader before the image. In embodiments using arcuate transports with concentric supply rolls, the device is more compact than prior-art systems with supply rolls arranged ahead of the printing modules. Unlike prior schemes, the amount of leader in the present invention is independent of the number of stations. This is particularly useful for additive-fabrication schemes, which can have tens of stations for jetting different components.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, some embodiments will be described in terms that would ordinarily be implemented as software programs. Those skilled in the art will readily recognize that the equivalent of such software can also be constructed in hardware. Because image manipulation algorithms and systems are well known, the present description will be directed in particular to algorithms and systems forming part of, or cooperating more directly with, systems and methods described herein. Other aspects of such algorithms and systems, and hardware or software for producing and otherwise processing the image signals involved therewith, not specifically shown or described herein, are selected from such systems, algorithms, components, and elements known in the art. Given the systems and methods as described herein, software not specifically shown, suggested, or described herein that is useful for implementation of any embodiment is conventional and within the ordinary skill in such arts.

A computer program product can include one or more storage media, for example; magnetic storage media such as magnetic disk (such as a floppy disk) or magnetic tape; optical storage media such as optical disk, optical tape, or machine readable bar code; solid-state electronic storage devices such as random access memory (RAM), or read-only memory (ROM); or any other physical device or media employed to store a computer program having instructions for controlling one or more computers to practice the method(s) according various embodiment(s).

FIG. 1is a schematic representation of an inkjet printer system10useful with various embodiments. Additional details are set forth in U.S. Pat. No. 7,350,902, the disclosure of which is incorporated by reference herein. Inkjet printer system10includes an image data source12, which provides data signals that are interpreted by a controller14as being commands to eject drops. Controller14includes an image processing unit15for rendering images for printing, and outputs signals to an electrical pulse source16of electrical energy pulses that are inputted to an inkjet printhead100, which includes at least one inkjet printhead die110.

In the example shown inFIG. 1, there are two nozzle arrays. Nozzles121in the first nozzle array120have a larger opening area than nozzles131in the second nozzle array130. In this example, each of the two nozzle arrays120,130has two staggered rows of nozzles121,131, each row having a nozzle density of 600 per inch. The effective nozzle density d in each array is thus 1200 per inch (i.e., d= 1/1200 inch inFIG. 1). If pixels on the recording medium20were sequentially numbered along the paper advance direction, the nozzles121,131from one row of an array120,130would print the odd numbered pixels, while the nozzles121,131from the other row of the array120,130would print the even numbered pixels. Printheads can include any number of nozzle arrays. In various embodiments, a printer includes one nozzle array.

In fluid communication with each nozzle array120,130is a corresponding ink delivery pathway122,132. Ink delivery pathway122is in fluid communication with the first nozzle array120, and ink delivery pathway132is in fluid communication with the second nozzle array130. Portions of ink delivery pathways122and132are shown inFIG. 1as openings through printhead die substrate111. One or more inkjet printhead dice110will be included in inkjet printhead100, but for greater clarity only one inkjet printhead die110is shown inFIG. 1. The inkjet printhead dice110are arranged on a support member as discussed below relative toFIGS. 2A-2B. InFIG. 1, first fluid source18supplies ink to first nozzle array120via ink delivery pathway122, and second fluid source19supplies ink to second nozzle array130via ink delivery pathway132. Although distinct fluid sources18and19are shown, in some applications it may be beneficial to have a single fluid source supplying ink to both the first nozzle array120and the second nozzle array130via ink delivery pathways122and132respectively. Also, in some embodiments, fewer than two or more than two nozzle arrays can be included on printhead die110. In some embodiments, all nozzles on inkjet printhead die110are the same size (within manufacturing tolerances), rather than having multiple sizes of nozzles on inkjet printhead die110.

Not shown inFIG. 1, are the drop forming mechanisms associated with the nozzles. Drop forming mechanisms can be of a variety of types, some of which include a heating element to vaporize a portion of ink and thereby cause ejection of a droplet, or a piezoelectric transducer to constrict the volume of a fluid chamber and thereby cause ejection, or an actuator which is made to move (for example, by heating a bi-layer element) and thereby cause ejection. In any case, electrical pulses from electrical pulse source16are sent to the various drop ejectors according to the desired deposition pattern. In the example ofFIG. 1, droplets181ejected from the first nozzle array120are larger than droplets182ejected from the second nozzle array130, due to the larger nozzle opening area. Typically other aspects of the drop forming mechanisms (not shown) associated respectively with nozzle arrays120and130are also sized differently in order to provide desired drop characteristics for the different sized drops. During operation, droplets of ink are deposited on a recording medium20. To print a multi-channel image, e.g., an image containing yellow

(Y), magenta (M), cyan (C), and black (K) image data, each image channel is printed separately using a respective nozzle array. Other colors, such as orange (Or), green (G), and transparent protectant (P) can be used in producing prints. As used herein, a “multi-channel image” is data defining respective patterns of a plurality of respective inks to be deposited on a receiver. This can be a conventional multi-color photograph or line-art image, or a mask set for a device to be fabricated by printing with additive-fabrication materials or etchants.

FIG. 2Ashows a plan, andFIG. 2Ban elevation, of a multi-component inkjet printer. Web receiver210is pulled from supply roll212, travels from left to right, and is wound onto take-up roll214. Printing modules220c,220m,220y, and220kextend across the full width of receiver210and deposit, respectively, cyan, magenta, yellow, and black ink. For example, cyan printing module220cdeposits cyan ink droplets225c. Any number, width, and color order of printing modules can be used. In embodiments using continuous or drop-on-demand inkjet printing, each printing module220c,220m,220y,220kincludes a respective printhead (not shown). Supply roll212and take-up roll214can be rolls of receiver material. They can also be drums or bars around which receiver210is entrained, and the initial supply and final take-up of receiver material can be performed by other components. This is represented graphically by the dashed extensions of receiver210. In various embodiments, supply tensioner222and take-up tensioner224are driven by motors (not shown). Supply tensioner222and take-up tensioner224maintain a selected tension on receiver210while it is being printed. Tension can also be maintained by underdriving supply roll212or overdriving take-up roll214. In various embodiments, tension is selected to maintain the surface of the receiver substantially normal to the ink or other colorant from each printing module220c,220m,220y,220k, without tearing the receiver210.

In embodiments, including those using printing technologies other than inkjet, each printing module220c,220m,220y,220kproduces on the receiver210, or causes to be produced on the receiver210, a separation image corresponding to one channel (e.g., C, M, Y, or K) of the multi-channel image to be printed. The printing modules220c,220m,220y,220kproduce the images without coming into mechanical contact with the receiver. That is, the receiver210and the printing modules220c,220m,220y,220kare spaced apart during normal operation, although they can come into contact if the receiver210buckles or cockles severely. Not all printing modules are necessarily used for each image.

FIG. 3shows an elevational cross-section of printing apparatus for printing a multi-channel image on a web receiver according to various embodiments. Printing modules220c,220m,220y,220k, receiver210, supply roll212, optional supply tensioner222, take-up roll214, and take-up tensioner224are as shown inFIG. 2. In some embodiments, feed roll310holds the receiver material; the web is entrained around supply roll212. Tension can be maintained by underdriving feed roll310. In other embodiments, a platen is placed under receiver210opposite one or more printhead(s)220c,220m,220y,220k, as discussed below with respect toFIG. 4.

Cutter320selectively cuts web receiver210to form printed sheets315. Cutter320can include one or more knives, rotary cutting blades, or automatic scissors or shears. Cutter320is arranged downstream of take-up roll214in the direction of travel of receiver210.

Transport305is a movable transport for web receiver210. Transport305includes optional feed roll310, supply roll212, optional supply tensioner222, receiver210, take-up roll214, take-up tensioner224, and cutter320. Transport305also includes mounting hardware (not shown) to hold these components in position with respect to each other so that all components of transport305can move past printheads220c,220m,220y,220ktogether. Transport305can be moved by a linear slide or driven belt. The movement of transport305, and the movement of receiver210past supply roll212and take-up roll214, causes receiver210to move in feed path240. Printing modules220c,220m,220y, and220kare arranged in sequence along feed path240, and are spaced apart from feed path240. In various embodiments, transport305is curved, or rotates (e.g., using a servo) rather than, or in addition to, translating.

In alternative embodiments, a collection roll (not shown) is used instead of cutter320. This permits roll-to-roll printing with reduced leader waste. In various embodiments, the collection roll is unwound into a second printing unit having a plurality of print modules to print images on the back side of receiver210. Alternatively, the collection roll can be removed from the printer and installed as feed roll310in the same printer or a different printer to produce backside prints. In these embodiments, the roll unwinds counterclockwise after installation as feed roll310, since it is wound onto the collection roll clockwise (or, in general, unwinds in the opposite direction of winding).

In still other embodiments, cutter320is a perforator, e.g., a full-width die punch or a wheel cutter with spikes that traverses the width of receiver210. In these embodiments, image content can be printed on receiver210up to the perforation on both sides. This reduces the length of the leader to the width of the perforation line, generally <0.5 mm. This provides printing with reduced leader, with reduced probability of bursting the perforations as can happen in a roll-to-roll process. Moreover, these embodiments provide prints one at a time, which is particularly useful in a kiosk. Mounting the perforator on transport305permits custom- or variable-length prints, as opposed to the fixed-length prints of pre-perforated receiver stock.

Transport405includes platen410, but does not include supply roll212, optional supply tensioner214, or optional feed roll310. Receiver210can bend as it reaches platen410(as shown), optionally over a roller or ski, or not. In various embodiments, platen410is curved to cause receiver210to follow a curved path, as will be discussed further below.

Transport drive406is represented graphically here for clarity; similar drives are present in other embodiments described herein. Transport drive406can include a ball screw, linear slide, piezoelectric actuator, servomotor, or other component providing linear or rotational motion. Controller486is also shown here; similar controllers are present in other embodiments described herein. Controller486is a CPU, PLD, PAL, PLA, microcontroller, FPGA, or other firmware or software device adapted to control the components of the printer.

Controller486is adapted to cause transport405to move past printing modules220c,220m,220y,220kto print a portion of the image, and to cause take-up roll214to draw receiver210across transport405(here, platen410specifically) to print the remainder of the image. This will be shown with reference toFIGS. 5-7, which show examples of the operation of a printer as inFIG. 3.

FIG. 5shows a printer as inFIG. 3with transport305in a first position. Printing modules220c,220m,220y, and220k, supply roll212, take-up roll214, receiver210, and cutter320are as shown inFIG. 3. In the first position, leading printing module220c(i.e., the first printing module a point on the receiver210encounters as it moves) is the first printing module over transport305. In embodiments using platen410(FIG. 4), leading printing module220cis the first printing module over platen410(FIG. 4). Transport305is operative in a first state to traverse from the leading printing module (here, printing module220c) to the trailing printing module (here, printing module220k). In the first state, take-up roll214is operative to retain receiver210in position with respect to transport305. In an embodiment, take-up roll214is braked in the first state (i.e., subjected to braking action, e.g., of a motor).

By “traverse from the leading printing module to the trailing printing module,” it is meant that transport305moves so that receiver210is successively brought into operative arrangement with each printing module220c,220m,220y,220k. InFIG. 5, transport305is positioned so that receiver210is in operative arrangement with, i.e., can receive a separation image from, only printing module220c. Receiver210will move with transport305to be in operative arrangement with more printing modules, and can be in operative arrangement with any number of printing modules simultaneously.

Controller486(FIG. 4) operates transport305and take-up roll214in the first state. Transport305begins moving to the right. Controller486(FIG. 4) then activates one or more of the printing modules220c,220m,220y,220kin sequence along feed path240(FIG. 3) to print a first portion of the image. Controller486(FIG. 4) determines which printing modules to activate using the image data.

Leader510is a portion of receiver210that is not printed since it is engaged with take-up roll214. Leader510cannot be brought into operative arrangement with any printing module (e.g.,220c). Leader510will be discussed further below. Various embodiments advantageously provide smaller leaders than prior schemes, reducing waste.

FIG. 6shows the printer ofFIG. 5with transport305having traversed to a second position so that receiver210is in operative arrangement with all four printing modules220c,220m,220y, and220k. Supply roll212, take-up roll214, receiver210, and cutter320are as shown inFIG. 3. In the second position, some of transport305can protrude beyond the printing modules (here, before printing module220cor after printing module220k). Cyan separation image620c(not shown to scale) was previously formed on receiver210and has been moved out from under printing module220cby the motion of transport305. Magenta separation image620mhas just been formed by printing module220m. Since the web receiver is in operative arrangement with the plurality of printing modules, controller486(FIG. 4) causes transport305to remain stationary. Controller486(FIG. 4) operates take-up roll214in a second state, in which take-up roll214draws receiver210across transport305(e.g., across platen410,FIG. 4). While take-up roll214is drawing receiver210across transport305, controller486(FIG. 4) activates one or more of the printing modules220c,220y,220m,220kto print a second portion of the image. In various embodiments, the first and second portions of the image together compose the whole image to be printed.

In various embodiments, controller486(FIG. 4) operates transport305and take-up roll214to provide a smooth transition between the first state and the second state. In an example, the speed of a point on receiver210with respect to one or more of the printing modules220c,220m,220y,220kis constant (within a selected tolerance) during a transition between the first state and the second state. Controller486slows transport305while speeding up take-up roll214so that receiver210continues moving relative to printing modules220c,220m,220y,220kthrough the transition and into the second state at the same speed it had in the first state. In various embodiments, transport305continues traversing until receiver210has reached a selected speed with respect to transport305.

In various embodiments, controller486(FIG. 4) includes a closed-loop feedback system to provide a smooth transition so that objectionable image artifacts are not created as transport305slows down. The control loop can also adjust the timing of printing of each line, or the amount of ink deposited, to hide artifacts resulting from velocity variations throughout the transition, e.g., due to the weight of the supply roll or friction in the system. For example, dynamic friction with transport305can slow down receiver210compared to its speed when take-up roll214is running. The feedback system can also monitor the speed of receiver210using a laser Doppler system or camera (similar to an optical mouse sensor) monitoring the surface texture of receiver210.

In one example, an inkjet press operating at a nominal web velocity of 200 m/min=131″/s and 300 dpi, each pixel passes a fixed point in 25.4 μs. Therefore, printing modules220c,220m,220y,220keach jet one line every 25.4 μs. It is desirable to move each dot no more than half a pixel from its intended position, so the pixel time is constant ±12.7 μs. Therefore, the speed of a given point on receiver210should be maintained between 133 m/min (25.4+12.7 μs) and 300 m/min (25.4-12.7 μs). This is “constant” as used above. In other embodiments, each dot moves no more than one-quarter of a pixel, here, ±6.35 μs.

Referring back toFIG. 5, in various embodiments, transport305moves with half of a desired web speed with respect to the printing modules220c,220m,220y,220k. Printing begins when take-up roll214reaches the midpoint of the group of printing modules, here between printing module220mand printing module220y. At that point, take-up roll214accelerates from stationary to an angular velocity appropriate to move receiver210with half the desired web speed in the same direction as transport305is moving. As a result, receiver210moves with the desired web speed. Referring toFIG. 6, as transport305completes its traverse and decelerates, take-up roll214accelerates to maintain receiver210at the desired web speed.

FIG. 8Ashows operation in the first state. Platen410is traversing and receiver210is held in position with respect to platen410(i.e., pulled along with platen410) by take-up roll214and take-up tensioner224. Feed roll310is turning as it is pulled by receiver210.

FIG. 8Bshows operation in the second state. Platen410is stationary and receiver210is being drawn across platen410by take-up roll214. Feed roll310is unwinding receiver210. Cutter320has cut a printed sheet315, which is falling into output tray888. Cutter320can also cut leader510(FIG. 5) from web receiver210. Leader510(FIG. 5) can fall into output tray888or can be deflected to a waste tray (not shown).

FIG. 9is a flowchart of methods of producing a print of a multi-channel image on a web receiver according to various embodiments. Processing begins with step905.

In step905, the web receiver is entrained around a take-up roll on a transport. Step905is followed by step910.

In step910, the transport is traversed past a plurality of non-contact printing modules. While the transport traverses, respective separation images are deposited on the receiver by activating the printing modules as they are brought into operative association with the receiver on the transport, so that a first portion of the image is printed. An example of this was shown inFIG. 5. By “traversed past” it is meant that the transport moves to successively bring the receiver into operative arrangement with more of the printing modules, until the receiver is in operative arrangement with the printing modules needed to produce the print image (and, optionally, other print modules not used for the particular image being printed). Once the receiver is in operative arrangement with the printing modules, the transport preferably does not move to remove the receiver from that arrangement until the print image is complete. Step910is followed by step915.

In step915, the receiver is drawn past the printing modules using the take-up roll and the printing modules are activated, so that a second portion of the image is printed. An example of this was shown inFIG. 6. Step915is optionally followed by step920or step925.

In optional step920, the printed portion is cut from the web receiver using a cutter downstream of the take-up roll in the feed path of the web receiver. An example of this was shown inFIG. 7.

In optional step925, the transport is returned to its initial position after printing the second portion of the image. The web receiver remains entrained around the take-up roll, so after the transport traverses back over its path, it is in position to print the next image. Step925is followed by step910. The transport can also return to its initial position so that additional ink can be deposited on the receiver. This permits depositing ink layers in an order different from the physical order of the printing modules along the receiver. This also provides drying time while the transport traverses back.

FIG. 10shows a method of producing a print of a multi-channel image on a web receiver according to various embodiments. This method uses a single printing module to deposit more than one layer. For example, in microelectronics processing, one printing module can include a jettable etchant used to etch multiple layers of silicon. Processing begins with step1010.

In step1010, the web receiver is entrained around a take-up roll on a transport. Step1010is followed by step1020.

In step1020, the transport is traversed past a plurality of non-contact printing modules. Respective separation images are deposited on the receiver by activating the printing modules as they are brought into operative association with the receiver on the transport. In this way, a first portion of the image is printed. Step1020is followed by step1030.

In step1030, the receiver is drawn past the printing modules using the take-up roll. The printing modules are activated to deposit respective separation images on the receiver, so that a second portion of the image is printed.

During printing of the first or second portions, a selected one of the printing modules deposits a first-layer separation image on a selected area of the receiver in the first or second portion. The selected area can also be divided between the first and second portions. Step1030is followed by step1040.

In step1040, the receiver is repositioned by returning the transport or rewinding the receiver, or both. The receiver is repositioned so that the selected area of the receiver is brought back into operative association with the selected printing module. In various embodiments, the receiver is rewound until only the leader is entrained around the take-up roll, then the transport is traversed back. Step1040is followed by step1050.

In step1050, the receiver is moved by traversing the transport or drawing the receiver, or both, as appropriate for the amount of repositioning performed. The selected printing module is activated while the receiver moves, and deposits a second-layer separation image on the selected area of the receiver.

This method is particularly useful in microelectronics fabrication. Devices such as solar panels can use 50 materials or more. Moreover, substrates for microelectronic devices can be very expensive. Substrates can include patterned glass and mono-crystalline silicon. Reducing leader waste is particularly useful with expensive substrates.

The invention is inclusive of combinations of the embodiments described herein. References to “a particular embodiment” and the like refer to features that are present in at least one embodiment of the invention. Separate references to “an embodiment” or “particular embodiments” or the like do not necessarily refer to the same embodiment or embodiments; however, such embodiments are not mutually exclusive, unless so indicated or as are readily apparent to one of skill in the art. The use of singular or plural in referring to the “method” or “methods” and the like is not limiting. The word “or” is used in this disclosure in a non-exclusive sense, unless otherwise explicitly noted.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations, combinations, and modifications can be effected by a person of ordinary skill in the art within the spirit and scope of the invention.

PARTS LIST