Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified...
Reexamination Certificate
1997-07-09
2004-06-22
Ahmad, Nasser (Department: 1772)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
C252S299010, C349S115000, C349S175000, C349S176000, C428S001100, C428S001300, C428S001310, C428S001600, C428S323000, C428S327000
Reexamination Certificate
active
06753044
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to broadband and spectrally-tuned circularly-polarizing reflective microflakes made from non-absorptive film material such as cholesteric liquid crystal (CLC) film material, and more particularly to a method of making super-white, mirror-like and additive-primary colored inks, paints and crayons embodying the same, for employment in additive-primary type coloring systems requiring radiation absorbing substrates.
2. Brief Description of Prior Art
In U.S. Pat. No. 5,364,557, Applicant has taught how to make CLC pigments for use in various applications. The advantage of using such CLC pigments is that color characteristics can be imparted to images painted and printed therewith by virtue of the reflection polarizing properties of CLC materials. In color printing, and in the fine arts, CLC color inks are known to possess much higher color saturation and brightness than conventional pigment and dyed based inks. This is in contrast with conventional pigments made from inorganic dyes where the color characteristics thereof are imparted to images painted and printed therewith by virtue of the absorption properties of such materials. A direct consequence of the absorption properties of prior art pigments based on inorganic dyes is that they are characterized by low reflection characteristics over their respective spectral bands. This makes the colors less bright than would otherwise be desired in many applications where a premium is provided for highly reflective paints, surface coatings, and the like, e.g. in the automotive industries, in particular.
However, CLC-based pigments based on the teachings of Applicant's U.S. Pat. No. 5,364,557 are not without shortcomings and drawbacks.
For example, Applicants have discovered that the reflection characteristics of prior art CLC-based microflakes differ on different sides of every CLC microflake. Consequently, as it is impossible to control microflake surface arrangement during application, the color purity and brightness characteristics of color coatings formed by prior art CLC microflakes are generally non-uniform and inadequate for commercial utility.
Moreover, when painting or printing on radiation absorptive surfaces (e.g. black paper) using CLC-based coloring media having “additive” primary color characteristics (e.g red, green and blue), there arises a great need for a CLC-based coloring media having “white” color characteristics in order to render color images with a full range of color shades and intensities, naturally required by human artistic expression. However, the only way in which to obtain the “perfect white” color characteristics using CLC-based coloring media having red, green and blue color characteristics, is to additively mix together CLC-based coloring media having “ideal” (i.e. spectrally pure) red, green and blue color characteristics, which have very narrow spectral reflection characteristics as shown in FIGS.
1
A
1
,
1
A
2
, and
1
A
3
.
FIG. 1B
shows the spectral reflection characteristics produced when CLC-based coloring media having “ideal” red, green and blue color characteristics are additively mixed together to produce “imperfect white” color characteristics.
In practice, however, CLC-based coloring having “actual” red, green and blue color characteristics have relatively wide spectral reflection characteristics, as graphically illustrated in FIGS.
1
C
1
,
1
C
2
and
1
C
3
. Consequently, when “actual” CLC-based coloring media having red, green and blue color characteristics are added together, it is not possible to produce the “perfect white” color characteristics, but only “imperfect white” color characteristics having spectral reflection characteristics as graphically illustrated in FIG.
1
D. As a result, when painting or printing with CLC-based coloring media having “actual” red, green and blue color characteristics, the color shade and balance of color images produce thereby invariably fall far short of the sought after ideal color characteristics made available using other coloring mediums.
Consequently, when using the prior art CLC-based coloring media taught in U.S. Pat. No. 5,364,557, it has been impossible to produce color images capturing the colorful aspects of nature in a faithful manner, nor produce color images having color tones and shades demanded by even those endowed with low levels of artistic expression.
Thus there is a great need in the art for a system and method of forming highly-reflective full-color images using coloring media that avoids the shortcomings and drawbacks of prior art printing and painting systems and methodologies.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide reflective microflakes for use in “super-white” and “additive-primary” coloring media (e.g. colored inks, paints, and crayons) while avoiding the shortcomings and drawbacks of prior art printing and painting systems and methodologies.
Another object is to provide such reflective microflakes made from circularly polarizing reflective material having improved spectral and band-pass position characteristics for imparting improved color characteristics.
Another object of the present invention is to provide such microflakes with a laminated construction, wherein each surface thereof exhibits symmetrical broadband reflection characteristics over particular regions of the visible band of the electromagnetic spectrum, in order to provide improved light reflectively and brightness when used in the manufacture of colored inks, paints and/or crayons of the present invention.
Another object of the present invention to provide such microflakes made from microscopic size fragments of thin CLC film material in which the axis of helical pitch of CLC molecules extends along the thickness dimension of the CLC microflake (i.e. transverse to the surface thereof), and in which the pitch of the helices of the CLC molecules varies in a non-linear (e.g. exponential) manner along the thickness dimension of each CLC microflake.
Another object of the present invention is to provide such CLC microflakes with a laminated construction, wherein each surface thereof normal to the helical axis exhibits symmetrical broadband reflection characteristics over the visible band of the electromagnetic spectrum, in order to provide improved light reflectively and brightness when used in the manufacture of super-white polarizing inks, paints and/or crayons of the present invention.
Another object of the present invention is to provide CLC microflakes which have reflection characteristics over the visible band of the electromagnetic spectrum which provide improved light reflectively and brightness when used in the manufacture of super-white polarizing inks and/or paints of the present invention.
Another object is to provide CLC microflakes made from both left-handed and right-handed circularly polarizing material having circularly-polarizing reflection characteristics over the entire visible band of the electromagnetic spectrum, for improved color characteristics.
Another object is to provide a method of fabricating CLC microflakes from circularly polarizing material having extremely broadband spectral reflection and transmission characteristics, low optical loss properties, high polarizing efficiency and low manufacturing cost.
Another object is to provide a method of fabricating circularly polarizing reflective microflakes having broadband spectral characteristics, low optical loss properties, high polarizing efficiency, simplified fabrication, and low manufacturing cost.
Another object of the present invention is to provide a novel method of fabricating broadband CLC-based pigments by producing CLC polymer films having liquid crystal molecules arranged along helical axes normal to the surface of the film, and then fragmenting the CLC film into flat flakes or platelets of microscopic size and thereafter mixing them in a suitable carrier medium for application onto the surface of particular radiation ab
Faris Sadeg M.
Li Le
Ahmad Nasser
Crispino Ralph J.
Perkowski Esq., PC Thomas J.
Reveo Inc.
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