Patent Application
20080158327
1. Field of the Invention
This disclosure relates generally to printing systems and, in particular, to a portable printing system for large areas that can be set up to print digital images on interior walls and ceilings of buildings and other manmade structures.
2. Background
Decoration of walls and ceilings are generally limited to a uniform paint application that is brushed, rolled or sprayed on or wallpaper which generally has a repetitive pattern. Those seeking a more pictorial treatment always have the option of hiring a painter to paint a mural, though this can be quite costly. Stenciling is another option, though, like wallpaper, it is generally applied in a repeating pattern.
With the onset of digital technology and digital printing in particular, new opportunities now exist for the application of detailed images on a variety of different surfaces and substrates. There are several limitations, of course, and these are generally with respect to the type of surface being printed on (the substrate) and the mechanical alignment between the print mechanism and the surface that will be receiving the image.
A wide variety ink jet printing devices have been described. Examples of such devices are found in U.S. Pat. Nos. 3,512,173; and 4,074,284 which described inkjets printers with removable print heads.
Several different methods have been used to eject the droplets.
U.S. Pat. No. 4,504,845 issued Mar. 12, 1985 to Erich Kattner describes a piezo-electric ink jet printer, where a piezo tube is used to drive the ink through a plurality of hollow tubes.
U.S. Pat. No. to 4,612,554 Michael Poleshuk on Sep. 16, 1986 describes a thermal ink jet printer where ink is ejected from a series of nozzles by selective application of current pulses to the heating elements in response to digitized data signals received by the printer.
U.S. Pat. No. 4,751,528 granted Jun. 14, 1988 to Charles Spherhly, et al., describes a hot-melt ink jet printer in which a solid ink made of a wax-like substance is melted then ejected onto a substrate whereupon it cools and re-solidifies. An electrical heater and a thermoelectric coolers are use to control platen temperature.
U.S. Pat. No. 3,893,623, granted to Richard A. Toupin on Jul. 8, 1975, describes an early ink jet printer where a stream of ink which is amplitude or frequency modulated to produce discrete droplets. A weir is located downstream from the jet orifice, near the point of drop formation where it contacts and deflects droplets of larger transverse diameter. The deflected droplets are caught in a gutter.
U.S. Pat. No. 4,250,510 John L. Dressler, issued Feb. 10, 1981 describes a continuous ink jet printer, wherein fluid filaments are stimulated to break up into jet drop streams directed at the fluid receiving medium. An electrically conductive catcher is used to deflect those drops not intended for the image. Drops which are not charged by the catcher means travel past the catcher means and are deposited on the fluid receiving medium. This approach allows the unused ink to be recycled, which is an important cost savings.
The question of large area printing is addressed in part by inventions such as U.S. Pat. No. 5,488,397 to Nguyen on Jan. 30, 1996. This device uses multiple printheads which move in a given scan direction to apply a swath of images to media which is periodically advanced in a media feed direction. In this case as in all the others above, the printhead scans across while the media is advanced perpendicular to the scan direction.
Murray, U.S. Pat. No. 5,686,947, issued Nov. 11, 1997 describes a large format ink jet printer with a large ink reservoir mounted inside the housing of the ink jet printer at a location which is remote from the ink jet cartridge and tubing connecting the ink reservoir to the ink jet cartridge. The large ink reservoirs may be stacked in side by side horizontal manner within the housing.
Robertson, U.S. Pat. No. 5,751,319 May 12, 1998 describes a system where an ink cartridge can be automatically replenished from a reservoir.
U.S. Pat. No. 6,180,228 to Bruno Mueller Jan. 30, 2001, describes an outdoor advertising system, where a multi-layer substrate is used to attach to a sidewalk or a road surface upon which images can be printed. The printed layer is then covered by a transparent protective layer.
Obviously, there is still a need for a portable printing system for large areas that can be set up to print digital images on interior walls and ceilings of buildings and other manmade structures.
Accordingly, the Portable System for Large Area Printing described herein is intended specifically for applying images to large flat surfaces such as those found in buildings. The system consists of a specialized set of inks and primers developed for this purpose with respect to their cost and durability, a printing head that can deliver the various colors of pigment or ink with appropriate carrier vehicle at a suitable resolution, a measurement and alignment system that is used to determine key dimensional characteristics of the intended target surfaces and surrounding structural elements, a portable computer containing a representation of the desired image and a software program that will drive the printing head and align and scale the desired image on the target surface with respect to the key target surface dimensions, and a modular adjustable printing frame comprised of a selection of extendable frame elements to be assembled in such a way so as to rigidly support the printing head during its operation, making use of surrounding and adjacent building elements in order to do so. The intent is for a skilled technician or contractor to assemble the printer in situ in a configuration that will support the printing operation for that particular site using adjacent walls or the ceiling and floor or any combination of the above that will provide the required structural stability for the printing operation. The printing head will then be attached to the frame along a scan rail. Said technician will then perform the necessary alignment measurements including the start position of the printing head and enter parameters into the computer. The software program will then perform the appropriate alignment and scaling operations and show a preview of the finished job. If the preview is accepted, the printing operation will begin. It is further intended that the administration of this printing service be structured as a franchise operation, with franchisees obtaining equipment, materials and training from the parent company at an appropriate cost and providing said parent company a percentage of earnings in return for the use of proprietary equipment as well as the company name.
The foregoing and other features of the exemplary embodiments will be apparent and easily understood from a further reading of the specification, claims and by reference to the accompanying drawings in which like reference numerals refer to like elements and wherein:
While preferred embodiments will be described hereinafter, it will be understood that it is not intended to limit the disclosure to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the disclosure as defined by the appended claims.
For a general understanding of the features of the exemplary embodiments, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to identify identical elements.
Referring now to
In step 50 the software is used to locate the print target area with respect to one or more physical datum points. This is used as a basis to project a virtual representation of the image upon the physical target. Once these data have been established, a two-dimensional coordinate system is developed that emanates from them. In step 51 a scanning operation is used to acquire a virtual map of the target area. This provides the software with a representation of the physical size of the target in terms of the virtual coordinate system used by the software. The map can also provide boundary information about the room itself. In many buildings, walls and ceilings are not perfectly square. Surfaces are neither perfectly vertical nor horizontal. Adjacent surfaces are not perfectly perpendicular and facing surfaces are not perfectly parallel. The map is created in 52 which gives the software program precise data from which image processing functions can be applied that can compensate for any target irregularities, by, for example, stretching or rotating the image to ensure that the edges of the completed image run parallel to the adjacent walls. In step 53 the detailed surface data of the target area is incorporated so that irregularities such as local curvatures in the wall surface can be compensated for by stretching the image over a curved section while stitching it together with its adjacent regions to provide a smooth and seamless appearance. In step 54 the software takes all of the data acquired in the previous steps and applies it to the virtual image so as to obtain a virtual print map. This includes any scaling or rotating functions, corrections for surfaces defects and so forth such that a virtual print map results which can be used to tell the computer exactly where and how to place every element of the image onto the target area. In step 55, any resolution enhancement processing is added. Since the image will be very large, it is likely that unless the digital image was of a very high resolution, some enhancement may be needed to avoid a grainy or jagged “pixilated” appearance that is common with digital images when they are displayed in a highly enlarged manner. For photographs a resolution of 120 to 200 pixels or dots per inch is commonly used. This would require an image file size of roughly 40 mega-pixels for a 3-foot by 4-foot picture or about 270 mega-pixels for an 8-foot by 10-foot picture. Because these wall pictures are to be viewed at some distance, a somewhat smaller resolution could be used satisfactorily, though the image file sizes would still be quite large, exceeding what conventional cameras are capable of by an order of magnitude or more. Resolution enhancement is an image processing technique commonly used in laser and inkjet printers to extend the effective resolution of an image, by algorithmically modifying pixel size in areas where it would be known to be beneficial, for example, when there is a curved line, smaller pixels are used to avoid a jagged appearance. The technique is also used in VLSI photolithography. An alternate way of effectively improving the resolution is to break the target image into a number of individual blocks, each of which would be of a reasonable file size, and then using the software to stitch the blocks together. This technique is already being using in digital cameras today in the so-called panorama mode. In step 56 the software can be used to drive the print head and the print head carriage to print a faint outline of the image to ensure that the image is located correctly before the complete image is laid down to avoid costly errors. In step 57 the actual printing is done. The software drives the print head carriage, the scan rail and the print head to ensure that the appropriate droplets of the appropriate colors are ejected at the appropriate locations. The print carriage speed is generally held constant with respect to the ink ejection rate, although this can be modified in curved or irregular areas so as to stretch or compress the image if so desired. Finally, in step 57 after the image has been applied to the surface, a drying and finishing operation may be applied to the image, to avoid any dripping or running of the image and to enhance the appearance and durability of the final product. A number of techniques such as heated air, radiant heat, Ultraviolet light or beamed microwave energy could be used to finish the drying process either immediately following the printing head at a fixed interval or as a separate operation after the image has been fully applied. Pressure could also be used with certain material sets to provide a more durable surface.
In recapitulation, a portable large area printing system has been described, which entails a temporary structural framework that is set up to support a number of scanning, printing and finishing operations, all precisely controlled by a computing device which combines a stored representation of the desired image with the specific requirements of the target area so as to produce a final image upon the target surface which could be a wall or a ceiling or other large areas. The system consists of a number of portable extendable structural elements, a specially adapted printing head and drive system, one or more distance sensors and the required software programs needed to combine these elements into the formation of a finished image upon the target surface.
While the invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit and scope of the invention as defined herein.
