Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1998-04-03
2001-06-05
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S264000
Reexamination Certificate
active
06243127
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process of forming an image usig a thermal recording element comprising metal layers which coalesce.
BACKGROUND OF THE INVENTION
In recent years, thermal transfer systems have been developed to obtain prints from pictures which have been generated electronically from a color video camera. According to one way of obtaining such prints, an electronic picture is first subjected to color separation by color filters. The respective color-separated images are then converted into electrical signals. These signals are then operated on to produce cyan, magenta and yellow electrical signals. These signals are then transmitted to a thermal printer. To obtain the print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye-receiving element. The two are then inserted between a thermal printing head and a platen roller. A line-type thermal printing head is used to apply heat from the back of the dye-donor sheet The thermal printing head has many heating elements and is heated up sequentially in response to one of the cyan, magenta or yellow signals. The process is then repeated for the other two colors. A color hard copy is thus obtained which corresponds to the original picture viewed on a screen. Further details of this process and an apparatus for carrying it out are contained in U.S. Pat. No. 4,621,271, the disclosure of which is hereby incorporated by reference.
Another way to thermally obtain a print using the electronic signals described above is to use a laser instead of a thermal printing head. In such a system, the donor sheet includes a material which strongly absorbs at the wavelength of the laser. When the donor is irradiated, this absorbing material converts light energy to thermal energy and transfers the heat to the dye in the immediate vicinity, thereby heating the dye to its vaporization temperature for transfer to the receiver. The absorbing material may be present in a layer beneath the dye and/or it may be admixed with the dye. The laser beam is modulated by electronic signals which are representative of the shape and color of the original image, so that each dye is heated to cause volatization only in those areas in which its presence is required on the receiver to reconstruct the color of the original object. Further details of this process are found in GB 2,083,726A, the disclosure of which is hereby incorporated by reference.
DESCRIPTION OF RELATED ART
U.S. Pat. No. 4,394,661 relates to a thin metal film that will coalesce or “ball up” when heated rapidly with a high-intensity laser beam. This leads to a covering power change and an increased optical transmission. However, there is a problem with using such an element in that the optical density is not sufficient for many applications. If a thick metal film is employed in order to increase optical density, then the efficiency for coalescence decreases and the size of the debris created upon heating increases.
U.S. Pat. No. 4,650,742 relates to a method of using an optical recording medium having two metal layers sandwiching a sublimable organic layer. There is a problem with this method, however, in that removing the sublimable organic layer requires a material collection apparatus and may be environmentally detrimental.
U.S. Pat. No. 4,499,178 relates to a method of using an optical recording material where a heat insulating layer is interposed between a metallic recording layer and a reflecting layer. There is a problem with using this method in that the reflecting layer does not coalesce and therefore does not add to the image contrast
It is an object of this invention to provide a method of forming an image wherein total optical density can be increased and the coalescence efficiency is improved, thus providing higher resolution using lower laser power. It is another object of the invention to provide a method of forming an image wherein a separate collection apparatus is not needed, and no material is ablated in the imaging process.
SUMMARY OF THE INVENTION
These and other objects are achieved in accordance with this invention which relates to a process of forming an image comprising imagewise-exposing, by means of a laser, a thermal recording element comprising a transparent support having thereon at least two metal layers having a melting point below about 2,000° C. and a substantially transparent, polymeric spacer layer separating each metal layer from another metal layer, thereby causing portions of each metal layer to coalesce in response to the imagewise exposure by the laser, thus forming the image.
It has been found that by separating a metal layer in a thermal recording element into multiple thin layers, the coalescence efficiency can be optiized while maintaining the total optical density. In addition, the size of the coalesced particles is minimized, thereby increasing resolution.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the process of the invention, there are at least two metal layers in the thermal recording element and less than 30 such layers, but preferably 3 to 10 metal layers, each metal layer separated from the other by a substantially transparent polymeric spacer layer.
The thickness of the metal layer in the thermal recording element employed in the invention is generally such that the layer absorbs relatively strongly at the exposure, viewing, and masking wavelengths, but not so thick as to provide high reflectivity or poor melting characteristics when exposed. In general, the thickness of the layer is about 10 Å to about 5000 Å, preferably about 50 Å to about 500 Å.
The total optical density of the thermal recording element employed in the invention should be relatively high to provide good viewing contrast in applications, such as medical imaging and effective absorption in the UV/Visible region when used in masking applications, such as imagesetter films and integral printing plate applications. For example, each layer should have an optical density to UV, visible or near IR light above about 0.2 and below about 3.0, preferably above 0.5 and below 2.0. The total optical density of the thermal recording element is preferably greater than about 1.0 and less than about 6.0, preferably greater than 1.5 and less than 5.0.
Metals useful in the thermal recording element employed in the invention have a melting temperature below about 2000 ° C., preferably below 1500° C. Such metals include, for example, transition metals or a group III, group IV or group V metal. Such metals include titanium, chromium, iron, cobalt, nickel, copper, zinc, aluminum, tin, molybdenum, palladium, gold, silver, cadmium, tantalum, bismuth, tin oxide, indium tin oxide, platinum or mixtures or alloys thereof. In a preferred embodiment, the metal employed is nickel or platinum.
The substantially transparent, polymeric spacer layer used in the thermal recording element employed in the process of the invention is generally a material which does not readily sublime or produce excessive gaseous emissions under the exposure conditions. A low melting point is advantageous to allow the exposed areas to anneal and to prevent delamination of the layers. Suitable materials include poly(vinyl alcohol)s, fluoropolymers such as polytetrafluoroethylene, polylvinyl butyral)s, cellulosics, poly(methyl methacrylates), poly(methacrylic acid)s, polystyrenes, polyamides, polyethyleneoxides, poly(isobut methacrylate)s, and polyethylenes. The polymers may be crosslinked. In a preferred embodiment, the polymer is poly(vinyl alcohol) or polytetrafluoroethylene.
A protective layer consisting of a relatively thick transparent polymeric layer or layers may also be applied over the top metal layer in order to provide scratch-resistance. Suitable materials include polymers that can be the same or different from the polymeric material used for the spacer layers and include polymers from the same list of materials. The polymers in the protective layer may also be crosslinked. In a preferred embodiment, the protective layer is poly(vinyl butyral).
T
Burberry Mitchell S.
Spahn Robert G.
Tutt Lee W.
Barlow John
Cole Harold E.
Eastman Kodak Company
Shah Manish S.
LandOfFree
Process of forming an image using a multilayer metal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process of forming an image using a multilayer metal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process of forming an image using a multilayer metal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2466046