Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Migration imaging – process – composition – or product – e.g.,...
Reexamination Certificate
1995-05-01
2001-01-30
Martin, Roland (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Migration imaging, process, composition, or product, e.g.,...
Reexamination Certificate
active
06180297
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a migration imaging process. More specifically, the present invention is directed to a migration imaging process in which one of the exposure steps entails the use of radiation of a specifically controlled wavelength. One embodiment of the present invention is directed to a process which comprises (a) providing a migration imaging member comprising (1) a substrate, (2) an infrared or red light radiation sensitive layer comprising a pigment predominantly sensitive to infrared or red light radiation, and (3) a softenable layer comprising a softenable material, a charge transport material, and a photosensitive migration marking material predominantly sensitive to radiation at a wavelength other than that to which the infrared or red light sensitive pigment is predominantly sensitive; (b) uniformly charging the imaging member; (c) subsequent to step (b), uniformly exposing the charged imaging member to a source of activating radiation with a wavelength to which the migration marking material is sensitive, wherein a filter comprising the infrared or red light radiation sensitive pigment is situated between the radiation source and the imaging member; (d) subsequent to step (b), exposing the imaging member to infrared or red light radiation at a wavelength to which the infrared or red light radiation sensitive pigment is sensitive in an imagewise pattern, thereby forming an electrostatic latent image on the imaging member; and (e) subsequent to steps (c) and (d), causing the softenable material to soften, thereby enabling the migration marking material to migrate through the softenable material toward the substrate in an imagewise pattern.
Migration imaging systems capable of producing high quality images of high optical contrast density and high resolution have been developed. Such migration imaging systems are disclosed in, for example, U.S. Pat. Nos. 5,215,838, 5,202,206, 5,102,756, 5,021,308, 4,970,130, 4,937,163, 4,883,731, 4,880,715, 4,853,307, 4,536,458, 4,536,457, 4,496,642, 4,482,622, 4,281,050, 4,252,890, 4,241,156, 4,230,782, 4,157,259, 4,135,926, 4,123,283, 4,102,682, 4,101,321, 4,084,966, 4,081,273, 4,078,923, 4,072,517, 4,065,307, 4,062,680, 5,055,418, 4,040,826, 4,029,502, 4,028,101, 4,014,695, 4,013,462, 4,012,250, 4,009,028, 4,007,042, 3,998,635, 3,985,560, 3,982,939, 3,982,936, 3,979,210, 3,976,483, 3,975,739, 3,975,195, and 3,909,262, the disclosures of each of which are totally incorporated herein by reference, and in “Migration Imaging Mechanisms, Exploitation, and Future Prospects of Unique Photographic Technologies, XDM and AMEN”, P. S. Vincett, G. J. Kovacs, M. C. Tam, A. L. Pundsack, and P. H. Soden,
Journal of Imaging Science
30 (4) July/August, pp. 183-191 (1986), the disclosure of which is totally incorporated herein by reference.
The expression “softenable” as used herein is intended to mean any material which can be rendered more permeable, thereby enabling particles to migrate through its bulk. Conventionally, changing the permeability of such material or reducing its resistance to migration of migration marking material is accomplished by dissolving, swelling, melting, or softening, by techniques, for example, such as contacting with heat, vapors, partial solvents, solvent vapors, solvents, and combinations thereof, or by otherwise reducing the viscosity of the softenable material by any suitable means.
The expression “fracturable” layer or material as used herein means any layer or material which is capable of breaking up during development, thereby permitting portions of the layer to migrate toward the substrate or to be otherwise removed. The fracturable layer is preferably particulate in the various embodiments of the migration imaging members. Such fracturable layers of marking material are typically contiguous to the surface of the softenable layer spaced apart from the substrate, and such fracturable layers can be substantially or wholly embedded in the softenable layer in various embodiments of the imaging members.
The expression “contiguous” as used herein is intended to mean in actual contact, touching, also, near, though not in contact, and adjoining, and is intended to describe generically the relationship of the fracturable layer of marking material in the softenable layer with the surface of the softenable layer spaced apart from the substrate.
The expression “optically sign-retained” as used herein is intended to mean that the dark (higher optical density) and light (lower optical density) areas of the visible image formed on the migration imaging member correspond to the dark and light areas of the illuminating electromagnetic radiation pattern.
The expression “optically sign-reversed” as used herein is intended to mean that the dark areas of the image formed on the migration imaging member correspond to the light areas of the illuminating electromagnetic radiation pattern and the light areas of the image formed on the migration imaging member correspond to the dark areas of the illuminating electromagnetic radiation pattern.
The expression “optical contrast density” as used herein is intended to mean the difference between maximum optical density (D
max
) and minimum optical density (D
min
) of an image. Optical density is measured for the purpose of this invention by diffuse densitometers with a blue Wratten No. 47 filter. The expression “optical density” as used herein is intended to mean “transmission optical density” and is represented by the formula:
D
=log
10
[l
o
/l]
where l is the transmitted light intensity and l
o
is the incident light intensity. For the purpose of this invention, all values of transmission optical density given in this invention include the substrate density of about 0.2 which is the typical density of a metallized polyester substrate.
High optical density in migration imaging members allows high contrast densities in migration images made from the migration imaging members. High contrast density is highly desirable for most information storage systems. Contrast density is used herein to denote the difference between maximum and minimum optical density in a migration image. The maximum optical density value of an imaged migration imaging member is, of course, the same value as the optical density of an unimaged migration imaging member.
There are various other systems for forming such images, wherein non-photosensitive or inert marking materials are arranged in the aforementioned fracturable layers, or dispersed throughout the softenable layer, as described in the aforementioned patents, which also disclose a variety of methods which can be used to form latent images upon migration imaging members.
Various means for developing the latent images can be used for migration imaging systems. These development methods include solvent wash away, solvent vapor softening, heat softening, and combinations of these methods, as well as any other method which changes the resistance of the softenable material to the migration of particulate marking material through the softenable layer to allow imagewise migration of the particles in depth toward the substrate. In the solvent wash away or meniscus development method, the migration marking material in the light struck region migrates toward the substrate through the softenable layer, which is softened and dissolved, and repacks into a more or less monolayer configuration. In migration imaging films supported by transparent substrates alone, this region exhibits a maximum optical density which can be as high as the initial optical density of the unprocessed film. On the other hand, the migration marking material in the unexposed region is substantially washed away and this region exhibits a minimum optical density which is essentially the optical density of the substrate alone. Therefore, the image sense of the developed image is optically sign reversed. Various methods and materials and combinations thereof have previously been used to fix such unfixed migration images. One method is to
Tam Man C.
Zwartz Edward G.
Byorick Judith L.
Martin Roland
Xerox Corporation
LandOfFree
Migration imaging process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Migration imaging process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Migration imaging process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2513865