Rotating element sheet material with dual vector field...

Details Rotating element sheet material with dual vector field... Rotating element sheet material with dual vector field...

2001-01-11

2004-02-10

Saras, Steven (Department: 2675)

Computer graphics processing and selective visual display system

Plural physical display element control system

Display elements arranged in matrix

C348S084000, C348S085000

Reexamination Certificate

active

06690350

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the preparation and use of rotating element sheet material including dual vector-field addressing components. More particularly, the present invention relates to the preparation and use of rotating element sheet material having both electric and magnetic addressing components.
BACKGROUND OF THE INVENTION
Rotating element sheet material has been disclosed in U.S. Pat. Nos. 4,126,854 and 4,143,103, both hereinabove incorporated by reference, and generally comprises a substrate, an enabling fluid, and a class of rotatable elements. As discussed more below, rotating element sheet material has found a use as “reusable electric paper.”
FIGS. 1 and 2
depict an enlarged section of rotating element sheet material
50
, including rotatable element
10
, enabling fluid
20
, cavity
30
, and substrate
40
. Observer
60
is also shown. Although
FIG. 2
depicts a cylindrically shaped rotatable element and cavity, many other shapes will work and are consistent with the present invention. As disclosed in U.S. Pat. No. 5,389,945, herein incorporated by reference, the thickness of substrate
40
may be of the order of hundreds of microns, and the dimensions of rotatable element
10
and cavity
30
may be of the order of 10 to 100 microns.
In
FIGS. 1 and 2
, substrate
40
is an elastomer material, such as silicone rubber, that accommodates both enabling fluid
20
and the class of rotatable elements within a cavity or cavities disposed throughout substrate
40
. The cavity or cavities contain both enabling fluid
20
and the class of rotatable elements such that rotatable element
10
is in contact with enabling fluid
20
and at least one translational degree of freedom of rotatable element
10
is restricted. The contact between enabling fluid
20
and rotatable element
10
breaks a symmetry of rotatable element
10
and allows rotatable element
10
to be addressed. The state of broken symmetry of rotatable element
10
, or addressing polarity, can be the establishment of an electric dipole about an axis of rotation. For example, it is well known that small particles in a dielectric liquid acquire an electrical charge that is related to the Zeta potential of the surface coating. Thus, an electric dipole can be established on a rotatable element in a dielectric liquid by the suitable choice of coatings applied to opposing surfaces of the rotatable element about an axis of rotation.
The use of rotating element sheet material as “reusable electric paper” is due to that fact that the rotatable elements are typically given a second broken symmetry, a multivalued aspect, correlated with the addressing polarity discussed above. That is, the above-mentioned coatings may be chosen so as to respond to incident electromagnetic energy in distinguishable ways, as indicated in
FIG. 2
, for example. Thus, an applied vector field can control the aspect of rotatable element
10
to favorably situated observer
60
.
For example, as disclosed in U.S. Pat. No. 4,126,854, hereinabove incorporated by reference, rotatable element
10
may comprise a black polyethylene generally spherical body with titanium oxide sputtered on one hemisphere, where the titanium oxide provides a light-colored aspect in one orientation. Such a rotatable element in a transparent dielectric liquid will exhibit the desired addressing polarity as well as the desired aspect.
II.A. Rotatable Elements with Two-valued Aspects
A multivalued aspect in its simplest form is a two-valued aspect. When the aspect is the chromatic response to visible light, a rotatable element with a two-valued aspect can be referred to as a bichromal rotatable element. Such a rotatable element may be fabricated by the union of two layers of material as described in U.S. Pat. Nos. 5,262,098 and 6,147,791, herein incorporated by reference.
FIGS. 3-6
depict rotatable element
10
with a two-valued aspect and an exemplary system that use such rotatable elements from the prior art. In
FIG. 3
, rotatable element
10
is composed of first layer
70
and second layer
80
and is, by way of example again, a generally cylindrical body. The surface of first layer
70
has first coating
75
at a first Zeta potential, and the surface of second layer
80
has second coating
85
at a second Zeta potential. First coating
75
and second coating
85
are chosen such that, when in contact with a dielectric fluid (not shown), first coating
75
has a net negative electric charge with respect to second coating
85
. This is depicted in
FIG. 3
by the “−” and “+” symbols respectively. Furthermore, the combination of first coating
75
and the surface of first layer
70
is white-colored, and the combination of second coating
85
and the surface of second layer
80
is non-white-colored, indicated in
FIG. 3
by hatching. One skilled in the art should appreciate that the material associated with first layer
70
and first coating
75
may be the same. Likewise, the material associated with second layer
80
and second coating
85
may be the same.
FIG. 4
depicts no-field set
110
. No-field set
110
is a subset of randomly oriented rotatable elements in the vicinity of vector field
100
when vector field
100
has zero magnitude. Vector field
100
is an electric field. No-field set
110
, thus, contains rotatable elements with arbitrary orientations with respect to each other. Therefore, observer
60
in the case of no-field set
110
registers views of the combination of second coating
85
and the surface of second layer
80
, and first coating
75
and the surface of first layer
70
(as depicted in
FIG. 3
) in an unordered sequence. Infralayer
55
forms the backdrop of the resulting view. Infralayer
55
can consist of any type of material, including but not limited to other rotatable elements, or some material that presents a given aspect to observer
60
.
FIGS. 5 and 6
depict first aspect set
120
. First aspect set
120
is a subset of rotatable elements in the vicinity of vector field
100
when the magnitude of vector field
100
is nonzero and has the orientation indicated by arrow
105
. In first aspect set
120
, all of the rotatable elements orient themselves with respect to arrow
105
due to the electrostatic dipole present on each rotatable element
10
. In contrast to no-field set
110
, observer
60
in the case of first aspect set
120
registers a view of a set of rotatable elements ordered with the non-white-colored side up (the combination of second coating
85
and the surface of second layer
80
as depicted in FIG.
3
). Again, infralayer
55
forms the backdrop of the resulting view. In
FIGS. 5 and 6
, rotatable element
10
, under the influence of applied vector field
100
, orients itself with respect to vector field
100
due to the electric charges present as a result of first coating
75
and second coating
85
.
FIG. 5
is a side view indicating the relative positions of observer
60
, first aspect set
120
, and infralayer
55
.
FIG. 6
is an alternate view of first aspect set
120
from a top perspective. In
FIG. 6
, the symbol ⊙ indicates an arrow directed out of the plane of the figure.
One skilled in the art should appreciate that first aspect set
120
will maintain its aspect after applied vector field
100
is removed, in part due to the energy associated with the attraction between rotatable element
10
and the substrate structure, as, for example, cavity walls (not shown). This energy contributes, in part, to the switching characteristics and the memory capability of rotating element sheet material
50
, as disclosed in U.S. Pat. No. 4,126,854, hereinabove incorporated by reference, and discussed in more detail below.
Further still, one skilled in the art should appreciate that no-field set and first aspect set discussed above in
FIGS. 4-6
can form the elements of a pixel, where vector field
100
can be manipulated on a pixel by pixel basis using an addressing scheme as discussed, for example, in U.S. Pat. No. 5,717,515, herein incorporated by r

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