Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
1997-08-22
2001-06-12
Niland, Patrick D. (Department: 1714)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031010, C106S031130, C106S031270, C106S031430, C523S160000, C523S161000, C524S187000, C524S210000, C524S230000, C524S589000, C524S590000
Reexamination Certificate
active
06245135
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a specific phase change ink composition that is useful for printing on various substrates, particularly transparencies, to produce high quality medical images such as x-ray, ultrasound, nuclear medicine, magnetic resonance, computer tomography, positron emission tomography, and angiography. In particular, the present invention relates to a phase change ink which may be used to create images that match the print quality and perceived appearance of black silver halide medical images. The ink is formulated by combining a black colorant, preferably a dye, having a deficient low absorbance region in the human visible response spectrum with at least one other colorant, preferably a dye, having a high absorbance region corresponding to the deficient low absorbance region of the black dye.
2. Background of the Invention
X-ray photographic films have long been used in medical imaging to help perform medical diagnoses. The black color generated from the development of silver halide photographic film has a somewhat brownish-black hue. A majority of the medical imaging photographic films today are produced on a blue tinted polyester transparent support to produce a more neutral black shade upon development of the silver halide film. Radiologists have been trained to read these films by looking for subtle gradations in optical densities in this particular black shade. Silver halide films for medical imaging have proven extremely useful in making medical diagnoses. However, the use of silver halide compositions for medical imaging has several disadvantages. These unimaged films are expensive, have limited shelf life, must be protected from light and other radiation, require chemical wet processing to develop an image, and disposal of the development chemicals employed raise environmental concerns.
It has been proposed to use in an ink jet imaging system commercially available phase change ink compositions having a black dye colorant on non-silver halide x-ray substrates having the same blue-tint or a clear or opaque appearance in medical diagnostic imaging applications.
It has been found that the resulting non-silver halide-containing films imaged with phase change ink in an ink jet imaging system are of diagnostic quality; however, the black color is different than what radiologists are accustomed to viewing. It was determined this different color (i.e. a bluish-black shade on the standard blue-tinted x-ray substrate) is due to great differences in the absorbance of the black dye over the visible wavelength spectrum from about 380 nanometers (nm) to about 670 nm compared to the absorbance of images generated on silver halide containing film. For example, with a standard black dye, such as Color Index (C.I.) Solvent Black 45, there are high and low absorbance regions. Furthermore, the absorbance in the 475 nm region was only about 60-70 percent of the absorbance in the 580 nm region. Accordingly, more light passes through the imaged substrate in the low absorbance region than in the higher absorbance region, causing an unintended shading difference on the imaged film substrate, again compared to an image created on a silver halide film.
Therefore, there is a need for an improved phase change ink composition which overcomes this problem created by the attempted use of commercially available back phase change ink for use on non-silver halide photographic film in medical diagnostic imaging applications.
BRIEF SUMMARY OF THE INVENTION
Accordingly, one aspect of the present invention is directed to a phase change ink composition comprising a phase change ink base in combination with a lightfast, thermally stable compatible black colorant system that includes a black coloring agent having at least one low absorbance region and at least one high absorbance region in the visible spectrum and at least one other coloring agent having a high absorbance band in the low absorbance region of the black coloring agent.
It is another aspect of the present invention that the colorant system comprises a combination of (1) a black coloring agent having an absorbance in the 475 nanometer region which is less than 80% of the absorbance at the 580 nanometer region and (2) a sufficient amount of at least one other color agent having an absorbance in the 475 nanometer region whereby the colorant system has a ratio of absorbances in the 475 nanometer region to the 580 nanometer region from about 0.92:1.0 to about 1.01:1.0.
Another aspect of the present invention is directed to a printed substrate comprising a substrate that has this phase change ink printed thereon.
It is a feature of the present invention that a black coloring agent and another coloring agent are combined in a phase change ink to obtain the desired optical density in the final imaged non-silver halide-containing transparency film for use in medical diagnostic imaging applications.
It is preferred feature of the present invention that the second coloring agent combined with the black coloring agent in the phase change ink is an orange dye.
It is another feature of the present invention that the ratio of the dyes comprising the colorant system when incorporated into an ink can be adjusted to yield an absorbance spectrum comparable to the absorbance spectrum on silver halide films between about 380 nanometers and about 650 nanometers.
It is still another feature of the present invention that the image produced from the phase change inks incorporating the black colorant system duplicates the silver halide black color perceived by the human eye when observed in the environment in which the medical images are normally viewed on a fluorescent lightbox.
It is an advantage of the present invention that the phase change ink produced from the combining of a process or composite black colorant, such as dye, and another colorant, such as dye, with a phase change ink base can be used in an ink jet imaging system that is environmentally friendly and a relatively low cost alternative imaging system to the chemical wet processing system using silver halide photographic film currently employed in medical diagnostic imaging.
It is another advantage of the present invention that the phase change inks employing the compatible black colorant system manifest no precipitates or print head inkjet orifice clogging when used in an ink jet printer.
It is another advantage of the present invention that the black colorant system is compatible in a phase change ink when used in an ink jet printer in medical diagnostic imaging applications.
It is a further advantage of the present invention that the black colorant system is stationary and does not migrate over time in the imaged areas.
It is still a further advantage of the present invention that none of the dyes in the black colorant system bloom; that is no dye crystallizes and migrates to the surface manifesting itself as a dust-like powder on the surface of the printed image.
These and other aspects, features and advantages are obtained in the ink of the present invention by the combining of a black coloring agent such as a dye having a low absorbance region with at least a second coloring agent such as a dye having a high absorbance region corresponding to the low absorbance region of the black coloring agent to produce an ink that is useful in ink jet medical diagnostic imaging applications to create images with black colored regions in the human visible response spectrum of from about 380 to about 670 nanometers that are comparable to images produced using black silver halide photographic film when viewed using a fluorescent light source typically used by radiologists.
REFERENCES:
patent: 4889560 (1989-12-01), Jaeger et al.
patent: 5000786 (1991-03-01), Matsuzaki
patent: 5372852 (1994-12-01), Titterington et al.
patent: 5389958 (1995-02-01), Bui et al.
patent: 5750604 (1998-05-01), Banning et al.
patent: 5764252 (1998-06-01), Burr et al.
patent: 0 546 403 A1 (1993-06-01), None
patent: WO 91/10710 (1991-07-01), None
Colour Index, vol.
Jaeger C. Wayne
King Clifford R.
Niland Patrick D.
Wells, St. John, Roberts Gregory & Matkin P.S.
Xerox Corporation
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