Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2003-02-24
2004-06-08
Epps, Georgia (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S290000, C040S406000
Reexamination Certificate
active
06747777
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to display subsystems and, more particularly, to a reflective microfluidics display particularly suited for large format applications that relies upon illumination from outside the display to strike the display and illuminate the image thereof, as opposed to an active display that produces illumination from within and consumes relatively more power thereof
BACKGROUND OF THE INVENTION
All displays, whether active or passive, must adhere to a color model. Red, green, blue (RGB) and its subset cyan, magenta, yellow (CMY) form the most basic and well-known color models. These models bear the closest resemblance to how humans perceive color. These models also correspond to the principles of additive and subtractive colors. Although these principles are applicable to all displays, these principles are of particular importance to the present invention and are to be further discussed herein.
Additive colors are created by mixing spectral light in varying combinations. The most common examples of this are television screens and computer monitors, which produce colored pixels by firing red, green, and blue electron guns at phosphors on the television or monitor screen. More precisely, additive color is produced by any combination of solid spectral colors that are optically mixed by being placed closely together, or by being presented to a human viewer in very rapid succession. Under either of these circumstances, two or more colors may be perceived as one color. This can be illustrated by a technique used in the earliest experiments with additive colors: color wheels. These are disks whose surface is divided into areas of solid colors. When attached to a motor and spun at high speed, the human eye cannot distinguish between the separate colors, but rather sees a composite of the colors on the disk.
Subtractive colors are seen by a human viewer when pigments in an object absorb certain wavelengths of white light while reflecting the rest of the wavelengths. Humans see examples of this principle all around them. More particularly, any colored object, whether natural or man-made, absorbs some wavelengths of light and reflects or transmits others; the wavelengths left in the reflected/transmitted light make up the color humans see.
This subtractive color principle is the nature of color print production involving cyan, magenta, and yellow, as used in four-color process printing. The colors cyan (C), magenta (M) and yellow (Y) are considered to be the subtractive primaries. The subtractive color model in printing operates not only with CMY, but also with spot colors, that is, pre-mixed inks.
Red, green, and blue are the primary stimuli for human color perception and are the primary additive colors and the relationship between the colors red, green, and blue, (known in the art) as well as cyan, magenta, and yellow (also known in the art) comprising the CMYK ingredients, where k signifies the color black, can be seen in
FIG. 1
herein with regard to illustration
10
. The formation of the color related to the RGB and CMYK color principles are shown by the illustration
12
of FIG.
2
.
As may be seen in
FIG. 2
, the secondary colors of RGB, cyan, magenta, and yellow, are formed by the mixture of two of the primaries and the exclusion of the third. For example, red and green combine to make yellow, green and blue combine to make cyan, and blue and red combine to make magenta. The combination of red, green, and blue in full intensity makes white (shown in FIG.
1
). White light is created when all colors of the EM spectrum converge in full intensity.
The importance of RGB as a color model is that it relates very closely to the way humans perceive color striking their receptors in their retinas. RGB is the basic color model used in television or any other medium that projects the color. RGB is the basic color model on computers and is used for Web graphics, but is not used for print production.
Cyan, magenta, and yellow correspond roughly to the primary colors in art production: blue, red, and yellow.
FIG. 2
also shows the CMY counterpart to the RGB model.
As is known in the art, the primary colors of the CMY model are the secondary colors of RGB, and, similarly, the primary colors of RGB are the secondary colors of the CMY model. However, the colors created by the subtractive model of CMY do not exactly look like the colors created in the additive model of RGB. Particularly, the CMY model cannot reproduce the brightness of RGB colors. In addition, the CMY gamut is much smaller than the RGB gamut.
As seen in
FIG. 3
for illustration
14
, the CMY model used in printing lays down overlapping layers of varying percentages of transparent cyan, magenta, and yellow inks. As further seen in
FIG. 3
, white light is transmitted through the inks and reflects off the white surface below them (termed the substrate
16
). The percentages of CMY ink (which are applied as screens of halftone dots), subtract inverse percentages of RGB from the reflected light so that humans see a particular color.
In the illustration
14
of
FIG. 3
showing one example, the white substrate
16
reflects essentially 100% of the white light which is used for printing in cooperation with a 17% screen of magenta, a 100% screen of cyan, and an 87% screen of yellow. Magenta subtracts green wavelengths from the reflected light, cyan subtracts red wavelengths from the reflected light, and yellow subtracts blue wavelengths from the reflected light. The reflected light leaving the magenta screen, is made up of 0% of the red wavelengths, 44% of the green wavelengths, and 29% of the blue wavelengths.
When the reflected light is used for printing on paper, the screens of the three transparent inks (cyan, magenta, and yellow) are positioned in a controlled dot pattern called a rosette. To the naked eye, the appearance of the rosette is of a continuous tone, however when examined closely, the dots become apparent.
When used in printing on paper, the cyan screen at 100% prints as a solid layer; the 87% layer of yellow appears as green dots because in every case the yellow is overlaying the cyan, forming green. The magenta dots, at 17%, appear much darker because they are mostly overlaying both the cyan and yellow.
In theory, the combination of cyan (C), magenta (M), and yellow (Y) at 100%, create black (all light being absorbed). In practice, however, CMY usually cannot be used alone because imperfections in the inks and other limitations of the process, full and equal absorption of the light are not possible. Because of these imperfections, true black or true grays cannot be created by mixing the inks in equal proportions. The actual result of doing so results in a muddy brown color. In order to boost grays and shadows, and provide a genuine black printers resort to adding black ink, indicated as K in the CMYK method. Thus, the practical application of the CMY color model is a four color CMYK process.
This CMYK process was created to print continuous tone color images like photographs. Unlike solid colors, the halftone dot for each screen in these images varies in size and continuity according to the image's tonal range. However, the images are still made up of superimposed screens of cyan, magenta, yellow, and black inks arranged in rosettes.
In the process involving CMYK printing, though it is chiefly regarded as being dependent upon subtractive colors, the process is also an additive model in a certain sense. More particularly, the arrangement of cyan, magenta, yellow and black dots involved in printing appear to the human eye as colors because of an optical illusion. Humans cannot distinguish the separate dots at normal viewing size so humans perceive colors, which are an additive mixture of the varying amounts of the CMYK inks on any portion of the image surface.
The CMYK process involving the interactions of its ingredients has many benefits. One of the benefits is that the net resulting color does not require an external source, such as found in the RGB process related to active
McMahon Sean P.
Sikora Robert M.
Cymscape Incorporated
Epps Georgia
Hanig Richard
McMahon John P
LandOfFree
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