U.S. patent application number 11/528756 was filed with the patent office on 2007-04-05 for electronic display systems.
Invention is credited to Richard V. Jessop.
Application Number | 20070075922 11/528756 |
Document ID | / |
Family ID | 37901395 |
Filed Date | 2007-04-05 |
United States Patent
Application |
20070075922 |
Kind Code |
A1 |
Jessop; Richard V. |
April 5, 2007 |
Electronic display systems
Abstract
A display or light-modulating device incorporates one or more
measures of liquid that obstruct or filter light that passes onto
or through the liquid; a space distribution of different
light-modulating filters, optical instrument or materials or of
materials that change the frequency or color of light passing onto
or through them, to emit a different frequency or color of light;
and means to apply electrowetting effect to controllably modulate
the location or shape of one or more measures of a polar or
conductive liquid, so that at least some portion of one or more
light-obstructing or light-filtering measures of liquids is caused
to be located between one or more light sources and the space
distribution of light-modulating filters, optical instruments or
light-modulating materials, or said space distribution of materials
that change the frequency or color of light passing onto or through
them, to emit a different frequency or color of light, thereby
controllably modulating properties of light emitted from said
device.
Inventors: |
Jessop; Richard V.; (New
York, NY) |
Correspondence
Address: |
DAVIDSON, DAVIDSON & KAPPEL, LLC
485 SEVENTH AVENUE, 14TH FLOOR
NEW YORK
NY
10018
US
|
Family ID: |
37901395 |
Appl. No.: |
11/528756 |
Filed: |
September 28, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60721712 |
Sep 28, 2005 |
|
|
|
Current U.S.
Class: |
345/49 |
Current CPC
Class: |
G09G 2300/06 20130101;
G02B 26/005 20130101; G09G 3/2003 20130101; G09G 3/3446 20130101;
G09G 3/348 20130101 |
Class at
Publication: |
345/049 |
International
Class: |
G09G 3/19 20060101
G09G003/19 |
Claims
1. A display or light-modulating device, incorporating: one or more
measures of liquid which serve to obstruct the passage of light, or
which filter light which passes onto said measure(s) of liquid; a
space distribution of different light-modulating filters, optical
instrument or materials; or a space distribution of materials which
convert or change the frequency or color of light passing onto or
through them, to emit a different frequency or color of light;
means to apply electrowetting effect to controllably modulate the
location or shape of one or more measures of polar or conductive
liquid, so that at least some portion of one or more
light-obstructing or light-filtering measure of liquids is caused
to be located between one or more light sources and said space
distribution of light-modulating filters, optical instruments or
light-modulating materials, or said space distribution of materials
which convert or change the frequency or color of light passing
onto or through them, to emit a different frequency or color of
light, thereby controllably modulating properties of light emitted
from said device.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn.
119(e) from U.S. Provisional Patent Application No. 60/721,712,
filed Sep. 28, 2005.
BACKGROUND OF THE INVENTION
[0002] U.S. Pat. No. 6,924,792, by the inventor hereof, teaches
various approaches to using electric fields and/or electrowetting,
and/or electrostatic techniques to move, or distort the shape of,
liquid droplets located between polymer (or other) substrates were
discussed, so as to change the color of light passing through
display systems.
[0003] The droplet would typically--but not invariably--be located
between two substrates or surfaces, at least one of which would
present a hydrophobic surface to (and in respect of) the
droplet(s), and said droplets could in some approaches be present
together with one or more other liquids (typically one other) where
said measures of liquid would, typically, be mutually-immiscible
(e.g., a polar liquid droplet together with a non-polar liquid such
as silicon oil).
[0004] Various different positions and designs of electrodes were
discussed to induce the droplet due to electrowetting effect to
change its location, or change its cross-sectional profile or
contact area with an surface which may be hydrophobic in respect of
that liquid in the absence, at least, of any electric field
affecting the surface energy relationship between liquid and
solid--and thereby to affect the passage of light passing onto or
through the droplet, so that, for example, the droplet focussed
light onto one or more selected colors on an adjacent multi-colored
filter array--and thereafter passed on, towards the display
screen.
[0005] The primary approaches discussed were (a) to change the
location, or change the shape of, droplets of a suitable liquid
functioning as optical lenses, which focussed light onto
differently-colored color filters; and (b) using similar
techniques, to change the location of dyed liquid droplets, passing
one or more droplets of the desired color into light paths, so that
they functioned as light filters. Optionally, suitable optical lens
arrangements could cause the resulting colored light to `fill` the
pixel area of the display.
[0006] In this new patent application, we will discuss different
dynamic color display screen and other light-modulating techniques,
devices and appr aches, which though in some cases employing many
fundamentally similar means of changing the location or shape of
droplets as were previously discussed, are also in these new
approaches concerned with using the droplets to perform functions
not previously discussed, or alternatively using the droplets in
different display or light color-changing arrangements than were
previously disclosed.
[0007] In any of the following approaches, it should be assumed
that the means of inducing a change of location or shape of the
droplet(s) is by employing electrowetting effect. There may be an
electrically insulating layer between the droplet(s) which are
affected by electrowetting effect and one or more electrodes
located on the other side of a substrate with which the droplet is
in contact; in other approaches, this electrically insulating layer
may, optionally, be absent.
[0008] It should also be understood, with any of the approaches
described below, that, optionally, any droplet or measure of liquid
which due to a change of shape or location of that droplet due to
electrowetting effect is causing a modulation of properties of
light may be either directly affected by an electrowetting effect
acting on it, or may alternatively be a measure of liquid which is
caused to itself change its location or shape due to one or more
other measures of liquid (which are affected by an electrowetting
effect) coming into physical contact with such a measure of liquid
(as a result of the other type of droplet's change of shape or
location due by electrowetting effect)--and as a result, the latter
droplet (unaffected by said electrowetting effect) is itself caused
to change its own shape or location. In such circumstances, the
above two different classes of droplets (or measures of liquid)
would normally be mutually-immiscible. This may be termed `passive`
change of a droplet's location or shape, due to a change of shape
or location due to electrowetting effect of some other measure of
liquid, where the `active` droplet as a result of its change of
shape or location causes the `passive` measure of liquid to itself
change location or shape. This patent, and all the descriptions of
different devices and arrangements for electrowetting devices,
includes within its scope optical changes which occur as a result
of either such a `passive` or such an `active` change or shape or
location of any measure of liquid.
SUMMARY OF THE INVENTION
[0009] Further electrowetting/electric
field-driven/electrohydrodynamic-driven liquid droplet-based screen
display approaches are disclosed herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The objects and advantages of the invention will be apparent
upon consideration of the following detailed description, taken in
conjunction with the accompanying drawings, in which the reference
characters refer to like parts throughout and in which:
[0011] FIG. 1 shows an arrangement of light-obscuring droplets used
with color filters.
[0012] The patent or application file contains at least one drawing
executed in color. Copies of this patent or patent application
publication with color drawings will be provided by the Office upon
request and payment of the necessary fee.
DETAILED DESCRIPTION OF THE INVENTION
The Use of Droplet Displacement to Achieve `Selective
Color-Blocking`
[0013] In one possible approach, instead of using droplets either
to focus or direct light onto appropriate color filters, or to pass
differently-colored droplets into and out of the path of light,
here we are using one or more light-obstructing or light-reflecting
(e.g., dyed) droplets to block, or obstruct, or absorb, or reflect,
controlled amounts of light from passing onto or through light
filters of different colors or onto any space distribution of
different light-modulating or light frequency-converting items or
materials--thereby enabling us to controllably modulate the color
or other properties of light which emerges at any particular
location of a screen display or light-projecting or
light-modulating device or system.
[0014] Where color filters are present, for example, changing the
location and/or the liquid-solid contact area of the
light-obscuring droplet at any time will consequently change the
color balance of light which passes onto or through any of the
colors in a space distribution of different color filters.
[0015] Optionally, the `light-obstructing` droplets described
herein may reflect light which would otherwise have passed directly
onto or through said color filters, were such one or more droplets
not located within light paths between the light source and the
color filters.
[0016] As an illustration of this approach, FIG. 1 shows one
possible arrangement. On the left-hand side, vertically aligned, we
see (from top, moving downwards) green, red and blue color filters
(as an example).
[0017] To the right of each of these filters, we see three measures
of liquid, subject to control by electrowetting means, which are,
in this example, colored black so as to obstruct the passage of, or
to absorb light which in the absence of said black droplets being
located at least partially in the light path(s) leading to the
colored droplets, would have passed onto/through the colored
filters.
[0018] By using electrowetting means to induce the black droplets
(in this example) to move to obstruct different portions of the
colored light filters, we are by this means able to determine the
respective amounts of light passing onto each of the three color
filters--and are thereby able to determine both the color balance,
and the amplitude, of the light which emerges from the system.
[0019] One or more optical lenses may be used to cause the light
from the different filters to `merge` at or before the display
screen, and to fill the `pixel area`, or to perform other optical
functions.
[0020] It should also be understood that time division
multiplexing, or various possible time-distribution techniques
which are well-known to those skilled in the art may be employed to
achieve the color-changing or other effects described in this
document.
[0021] As an example of this, in FIG. 1, below, instead of varying
the location of the black droplet to block or obstruct different
amounts of light from reaching the color filters, a
time-distribution approach could alternatively be employed to
achieve a similar result--where for example the black droplet might
only have two possible positions: (1) totally obscuring the color
filter; and (2) not obstructing the passage of any light onto a
particular color filter.
[0022] In such an approach, by changing the ratio of time duration
between the above two different states, it is possible to
controllably vary the perceived intensity or amplitude of light of
the color of that particular color filter that is emitted by the
system. Clearly, by applying this approach to more than one filter
of different colors, it is possible to controllably vary the
perceived average color, or intensity, of a pixel, for example, on
a screen display system.
[0023] It should also be understood that although, in the following
document, I have used color filters as an example of the means by
which the change of shape or location of a light-obscuring/light
absorbing/light reflecting measure of liquid can vary the amplitude
or light passing onto or through said color filters, the same
approach may alternatively be employed in respect of any surface or
plurality of surfaces incorporating a space distribution of
different light-modulating properties or different light frequency
converting materials, where said change of location or shape of
said measure of liquid due to electrowetting effect causes a change
in the amplitude or intensity or other properties of light passing
onto one or more locations within said space distribution of
different light-modulating or frequency-converting areas
incorporated within a device.
[0024] It should be noted, thus, as an example, that this approach
may be employed to controllably modulate the amplitude (or other
properties of light) of (e.g., ultra-violet, or near-UV) light
passing onto different florescent or `down-converting`, or light
frequency-converting materials, so as to controllably modulate the
colors, or light intensity, or other properties of light which
emerge from such a system.
[0025] In such an arrangement, for example, the amplitude of
ultra-violet light (if that were the exciting frequency, for
example) being allowed to reach different light-frequency
converting materials due to the EW-achieved change of shape or
location of such measures of liquid can be controllably
modulated--thus causing, for example, a corresponding change of
emitted colors of light by said frequency-changing materials due to
different amounts of light reaching each of a number of different
such materials which convert light into a different, (usually
visible) frequency or color of light.
[0026] This principle is applicable to all of the inventions
described here. Similarly, instead of a range of different
frequency-converting materials emitting light of different
frequencies or color due to their innate frequency of light or
light-converting properties, as merely another of almost
innumerable possible examples of the same principle, said space
distribution of different light-modulating properties might be one
or more surfaces which refracted or reflected the incoming light in
different directions, or with other different light-modulating
effects: thus, by changing the shape or location of a measure of
liquid due to electrowetting effect--and thereby changing
properties of light reaching different locations of such
angle-of-light-changing surfaces (or other light-modulating
properties--the respective ratio of light which was reflected or
refracted (for example) by the different surfaces would be
controllably modulated.
[0027] Thus, to be clear, taking FIG. 1 as an example, said green,
red and blue color filters might instead be different light
frequency-changing, or for example `down-converting` materials--and
by changing the location or shape of the droplets shown, we are
able to modulate the amplitude or intensity (or other properties)
of light (e.g., ultra-violet light) which reaches those light
frequency-changing materials.
[0028] Finally, it should be understood that whilst in the
following examples I have given the droplets' color as being black,
they could alternatively have been of any other color--thereby, for
example, providing the means of themselves modulating the color or
other properties of light passing onto or through said (for
example) color filters.
[0029] Equally, it should be understood that such measures of
liquid as are being change in location or shape--directly or
indirectly, or `passively or `actively` as described above--by
electrowetting effect could themselves include, or incorporate,
florescent or light frequency-converting materials.
[0030] FIG. 2 shows a different but related approach, where a
single black-colored droplet is moved in respect of a number of
different color filters. Optionally, in this approach, the location
and/or the size of the droplet can be changed by electrowetting
effect (i.e., the cross-sectional profile, or area of
droplet/surface contact can be modulated by electrowetting
effect--thus changing its total area in contact with a hydrophobic
surface where said hydrophobic properties in respect of said
measure of liquid have been changed by electrowetting effect). The
various means of employing electrowetting effect to change the
shape and/or the location of droplets are well-known to those
skilled in the art--and are in addition discussed in my existing
published US patent on electrowetting display means.
[0031] In essence, however, such methods employ electrodes located
adjacent to the droplet(s) in question to create an electric field,
which in turn causes a change in the surface energy relationship
between one or more droplets on the one hand, and the hydrophobic
layer or material with which the droplet comes into contact on the
other.
[0032] An increase in electrical potential applied in such an
approach typically causes a hydrophobic surface to become less
hydrophobic--or to become hydrophilic--in respect of such a
droplet. Thus, by causing a surface adjacent to a droplet to become
less hydrophobic in respect of a droplet (e.g., a polar droplet)
due to electrowetting effect, said droplet can be induced to change
location to position itself in contact with that location adjacent
to an electrode which is less hydrophobic in respect of the droplet
than surrounding adjacent locations on the surface along which said
droplet is able to move.
[0033] The same basic approach can be employed to change the area
of contact between the droplet and the surface--as is similarly
well-known to those skilled in the art. Bruno Berge is credited
with conceiving such a system for the purpose of achieving variable
focal length liquid lenses.
[0034] A `color wheel`, or any other suitable multi-color filter
arrangement, could alternatively be used, where the black droplet
is moved controllably in front of the wheel to block selected
portions of selected colors. The particular size of the droplet
shown does not suggest an ideal size for this droplet, and is used
purely for illustrative purposes.
[0035] With reference to the alternative `windows` approach
described in this document (see below), where instead of blocking
or obstructing light, the droplet (e.g., a polar or conductive
droplet) is more light-transmissive, or allows more light to pass
through it, or has different light-transmitting or light-modulating
properties from, a second liquid with which it is
mutually-immiscible and in contact (e.g., a non-polar liquid), it
should be appreciated with reference to, for example, FIGS. 2 and
3, that such a `window droplet` could replace the shown `black
droplet` in these drawings--and wherever the droplet was located,
the light would pass through it and onto or through the filters (or
other light-modulating or frequency-converting materials or
items)--and wherever the droplet was not located in respect of the
aforementioned items or filters, light would either not be able to
pass onto or though them (because, for example, the second--e.g.,
non-polar--liquid might either block or totally obstruct or absorb
the light) or because the 2nd liquid would be less
light-transmissive, or would have different light filtering
properties from the first droplet.
[0036] Clearly, such a `window droplet` could be changed in either
its location or its total area of contact (thus its size) by
electrowetting effect. Thus, in the most simple `clear droplet in
black 2nd liquid` example, we would effectively be looking at a
hole through which light can pass, and which can be expanded or
contracted in area, and which can be changed in location along a
hydrophobic surface in respect of the different elements upon which
light will pass, having passed through the `window`--and this
`hole`, or light path, would in this example be surrounded by a
black, or light-reflecting area (the second liquid) through which
it could not pass. Thus, we would have a very flexible and
innovative light-modulating system for selecting which items in a
space distribution of different light-modulating for light
frequency-converting items light passed onto or through at any
time
[0037] In FIG. 3, the black liquid droplet has increased in size,
and is now largely obscuring most of the light coming from/going to
the red and green color filters, with the result that now the light
emerging from the system will be a different color, composed of
more blue than red or green.
[0038] From the above, it is clear that by moving,--and/or,
optionally, changing the size of--a liquid droplet which prevents
much or all light falling on it from penetrating it, we can control
the color of the light emerging from the system.
[0039] It should also be pointed out that if a `color wheel` type
of multi-color filter is used, a special layout of the different
colors in the visible spectrum could be provided that would enable
a single dark-colored droplet of fixed size to provide the greatest
possible number of color combinations to the display, by blocking
appropriate areas of the `color wheel` filter.
[0040] In the above example--as in many of the other approaches
described in this, and my U.S. Pat. No. 6,924,792--the droplet may
be used on its own, sandwiched between two substrates, at least one
of which must be transparent or translucent, or it may be located
together with a 2nd liquid or fluid--where, typically, such
different liquids (e.g., polar and non-polar, respectively) would
be mutually-immiscible.
[0041] Elsewhere in this document, a similar approach is used, with
the difference instead of employing one or more measures of liquid
that function to obstruct, or reflect some portion of light from
passing onto a particular sector of a space distribution of
different light-modulating elements (e.g., color filters), and
thereby to control the (e.g.) color of the light which emerges from
such a system, instead one or more measures of liquid is used to
perform a kind of inversion of this approach--i.e., that more light
passes through, for example, a droplet than passes through liquid
(typically mutually-immiscible with the first liquid) which is
surrounding the first liquid.
[0042] In this way, the droplet acts as a type of `window` to
permit light (or a greater amount of light, for example) to pass
through it than passes through the surrounding liquid.
[0043] Thus, taking an one example of an application of this
principle, if a transparent droplet were located adjacent to a
number of differently-colored color filters, then by employing
electrowetting effect to change the position or size of that
droplet, the amount of light which passes through that droplet and
passes subsequently onto or through the differently-colored filters
can be controllably modulated--thus providing a novel color display
or dynamically color-changeable light-projection means.
[0044] Equally of course, this `window` approach can be used to
control the amount of light, or alternatively other properties of
light, which passes onto any space distribution of different
light-modulating or light frequency-converting filters or materials
located adjacent to said liquids.
[0045] Thus, as an example, ultra-violet (or near ultra-violet)
light might be employed as a light source, with one droplet under
electrowetting control allowing that light to pass through to
selected frequency-converting materials located on the other side
of the droplet from the light source--and another liquid, typically
mutually-immiscible with the first liquid, may prevent such light
from passing onto such (e.g.) `down-converting` materials of
different properties located on the other side of the droplet from
the light source, and within the same space distribution of such
different light frequency-converting materials.
[0046] By this means, it is possible to controllably modulate which
different light-modulating materials, filters or other elements are
illuminated by the light source--and also to control the respective
amplitude of light which passes onto such different
light-modulating items or materials at any one time. Time
distribution techniques may be employed, optionally, to
controllably modulate properties of light which passes onto such
different filters, frequency-converting materials or elements.
[0047] Several of the droplet-moving systems described in my
previous patent applications show how liquid droplets can be
controllably moved over a surface, and how this can be used for
display, light-projecting, and/or dynamic color-changing (of
emitted light) purposes.
[0048] However, to refresh the reader's memory, I shall now give
one or two examples, applied to this particular application of
droplet-moving techniques, wherein the function of the droplet is
to selectively prevent, or reduce, the amount of light that has, or
will, pass through different color filters (or other items, as
described above), and thereby controlling the color or other
properties of light that will exit the system.
[0049] In cross-section, FIG. 4 is a drawing, simplified for the
purposes of clarity, showing one of many possible ways that the
system could be arranged for one particular cell, or `pixel`. In
this particular approach, three electrodes are located below a
substrate or layer which--at least in the absence of electrical
potential being applied to one or more of the electrodes shown--is
hydrophobic in respect of the black droplet shown. A ground plane
is shown located above another substrate located above the
droplet.
[0050] Thus, in this simple example, by applying suitable
electrical potential to electrodes A or C (since the droplet is
currently located above electrode B) and with no potential applied
to electrode B), an electric field can be created which causes an
electrowetting effect to cause the droplet (e.g., a polar droplet)
to be induced to locate itself above the electrode to which the
electrical potential has been applied--thereby reducing the amount
of light which would pass upwards (in the above diagram) through
the particular color filter which is being partially or wholly
`blocked` from the light source by the droplet.
[0051] In the above type of arrangement, transparent electrodes, or
conductive material, (e.g., ITO) may optionally be used;
alternatively, non-transparent electrodes may be used, where they
are so shaped that light passes through areas not occupied by the
electrodes; optical lenses, for example, may be used as described
in the prior art to focus or direct light through `holes` or slots
in the electrode areas.
[0052] It should be noted that drawings herein do not generally
show lenses and other optical arrangements or electrical
arrangements (e.g. electrodes or address lines, etc), many of which
have been alluded to in the prior applications and other prior art,
since the concern here is to introduce the principle of moving
droplets to as to selectively modulate properties of light passing
onto or through different items in a space distribution of such
items, rather than covering optical and electrical, and particular
electrowetting configurations and techniques, which are well-known
to those skilled in the art, and are documented in prior art.
[0053] Almost innumerable alternative arrangements of the
electrodes can be used, the options for which are well-known to
those skilled in the art. Almost any practical number of electrodes
could be used, for example, beneath the lower substrate layer shown
above, and any appropriate number of them could be charged with all
the same, or different, polarities--with or without the use of the
electrode above the upper substrate acting as a ground plane, or as
a counter-electrode--so as to produce a very large number of
different possible fields, or combinations of electric fields,
acting on the droplet.
[0054] Thus, the droplet may, for example, be distorted in its
shape, either in terms of the profile (cross-sectional view) and/or
its shape when viewed from above, in terms of the drawing above. In
combination with a suitable pattern of color filters, and/or a
suitable pattern of wetting surfaces on the inner face(s) of the
substrates, a vast number of possible positions and shapes for the
droplet can be controllably achieved.
[0055] In U.S. Pat. No. 6,924,792, the possible use of one or more
resistant electrodes was discussed as a means of controlling the
location of the droplet.
[0056] FIG. 5 shows a simplified drawing of one means by which a
resistant electrode could be used to change the location of a
droplet by electrowetting means along one axis (though the same
approach is applicable to more than one axis), by creating electric
fields of different strengths at different points along the
hydrophobic (at least, hydrophobic in the absence of an electric
field, and subject to the other methods discussed in this document
for a permanent treatment of the surface with a space distribution
of different hydrophobic properties) substrate surface adjacent to
those sectors of the resistant electrode.
[0057] In some approaches, a permanent pre-treatment of one or more
of the surfaces with which the droplet is in contact may be applied
to produce a gradient of progressively increasing hydrophobicity
may be employed--as shown in the diagram.
[0058] FIG. 5 provides a simplified, graphical illustration of this
point. It should be noted that this, and all other methods of
controllably moving or manipulating droplets discussed herein or in
earlier applications, are equally applicable to droplets which are
designed to be light-obstructing, or are dyed, or are acting as
`liquid lenses`, or are, or incorporate, materials with properties
to convert, or `down-convert` the frequency of light which passes
onto them, or are acting as vehicles to carry solid lenses or other
optical devices (see more, below). Equally, light-obstructing
droplets may optionally be located within other, non-immiscible,
liquids.
[0059] Depending upon the particularly configuration of the device
and its particular purpose, a second electrode, which may be a
second resistant electrode, or may be a conventional electrode, may
be provided `above` the droplet in the diagram below, to provide a
difference of electrical potential between different points along
one or both electrodes--thereby governing the strength and
distribution of electric field between the two electrodes--and
thereby governing the distribution of hydrophobic properties along
one or more surfaces with which the droplet is in contact.
[0060] FIG. 5 is only provided for the purposes of example: there
are many alternative means of controlling the distribution of
electric field--and thus the hydrophobic properties at different
points along one or more surfaces due to electrowetting
effect--that the general principle of the resistant electric can be
employed to achieve. As is explained above, whereas different color
filters are shown in the diagram, these could be replaced with a
space distribution of any range of different light-modulating
properties, or light frequency converting materials with different
frequency-converting properties.
[0061] Clearly, it is, optionally, possible to provide duplicate
resistant electrodes on the same axis both below and above the
droplet; it is also, alternatively or complimentarily, possible to
use this principle in more than one axis, so as, for example, to
provide 2-axis movement of the droplet to whatever location is
desired so as to block different amounts/proportions of light from
passing from or to the different color filters, and onwards to the
viewing screen--i.e., to whatever proportion is desired in the case
of each filter--and thereby to determine the color of light
emerging from the system.
[0062] Clearly, such an approach, employing electrowetting effect,
can also be used to change the location or shape of droplets used
to provide functionality other than `light blocking`--e.g.,
droplets directing (e.g., focussing, or reflecting) light towards
selected color(s) or a space distribution of different
light-modulating or frequency-changing properties, and so on.
[0063] FIG. 6 provides a graphical representation of the `2-axis
resistant electrode` approach: here, the shape of the resistant
electrodes has been distorted for clarity, and the blue triangles
represent increasingly non-wetted surfaces adjacent to the higher
voltage ends of the respective resistant electrodes.
[0064] FIG. 7 shows a different (simplified) representation of such
an arrangement. As with other diagrams herein, only elements of the
design relevant to making the current points clear are shown in the
drawing.
[0065] In FIG. 7, we are looking down (plan view) on one possible
arrangement of a `pixel` of a display employing the movement of a
droplet. The brown square represents the substrate area; the
turquoise rectangle is a resistant electrode (say) immediately
underneath the lower substrate, and the rectangle marked with a
dotted line is another resistant electrode, which may be located
immediately adjacent--above or beneath--the first, or in another
alternative approach, is located above the top substrate of systems
such as those shown above.
[0066] The important point here is that by arranging the two
resistant electrodes so that they are, for example, at right angles
in orientation to each other, we are able to use the `resistant
electrode+ varying surface wettability` approach described above to
control 2 different axis of movement--and thus to move the droplet
to wherever we wish, or to change its shape in many different
possible directions, or to achieve blocking, or `controlled passage
of light` by the `window approach` described in this document--of
whatever colors or other space distribution of light-modulating or
frequency-modulating elements is desired, as shown in FIGS. 2 and 3
above, or to focus, or reflect, light onto different filters or
other of the aforementioned light-modulating or frequency-changing
items, so as to control the colors, or other properties of light,
emerging from the system.
[0067] The voltages shown in the drawing are merely given for
illustrative purposes, to show that there is a voltage difference
applied to different points, or ends, or sides, of the
electrodes.
[0068] With respect to the resistant electrode arrangements
discussed above, it should be said that of course these only
represent one example of how to control the location of the
droplets: there are innumerable other ways, using techniques well
known to those skilled in the art, of applying the necessary
electrical potential or voltage to move the droplets to the desired
location--some of which are described in my U.S. Pat. No.
6,924,792. But whereas most--if not all--other approaches for
achieving many different possible locations for the droplet rely on
many different, often separately-addressable electrodes, the great
advantage with the resistant electrode is that it keeps the number
of address lines very low.
[0069] One optional possible arrangement of the resistant
electrodes shown in the above diagram, for example, would be to
locate one above the upper substrate (i.e., above the droplet in
cross-sectional termns), and the other below the lower
substrate.
[0070] FIG. 8 shows how the wettability gradients, or gradients of
hydrophobic properties, could be arranged for a system as described
in FIG. 6 and 7. However, it should be understood that the scope of
claims within this patent with respect to resistant electrodes are
not in any way limited to this type of electrode being used in
combination with one or more gradients of wettability or
hydrophobic properties: these are provided only for the purpose of
illustrating one method of employing resistant electrodes to change
the shape or location of measures of liquid being changed in shape
or location by electrowetting effect.
[0071] In FIG. 8, the two red triangles represent the gradient of
hydrophobic properties in respect of the droplet in the
`north-south` axis (in respect of electrode 1), and in the
`east-west` axis, in respect of electrode 2. The application of a
wettability gradient--say, screen printing, for example--of the
inner faces of the two substrates could be executed, for example,
by only applying the gradient in one axis for each substrate
respectively.
[0072] Alternatively, of course, the varying hydrophobic properties
on the relevant substrate surfaces (i.e., those within which the
droplet is in contact, or may come into contact) could optionally
be applied in both axis on either or both surfaces or in both axis
for both substrates, etc. Thus, for example, a surface facing and
immediately adjacent the droplet could on the same face of a single
substrate (using points of the compass metaphorically) increase
wettability from East to West, and also increase wetting from a
lowest level at North towards a highest level at South.
[0073] It should be pointed out here that while FIGS. 2 and 3 show
red, green and blue color filters arranged in a triangular format,
there is no real limit to either the choice of the number, or the
color of the color filters in systems where the droplet is
providing a `color-blocking` or light-focussing, or `controlled
passage of light` via the `window` approach described herein
function, nor in the arrangement of how those colored filters are
arranged in respect of each other, or in respect of the droplet. A
`rainbow-like` line, for example, incorporating many or all colors
in the visible spectrum could be laid down, and the droplet could
simply move up and down that `spectrum line`.
[0074] Equally, there could be more than one droplet employed for
one or more filters or other elements or locations within a space
distribution of different light-modulating or frequency-converting
items within (for example) each pixel of the display: the droplets
could be separately addressable--due, for example, to the material
of which they are composed (as for example those discussed in my
existing published electrowetting US patent) or, for example,
because separately-addressable electrodes control different
droplets confined within different areas of the pixel color
filtering system that do not encroach on, or `overlap`, each other.
Thus, there could be, for example, one black-dyed droplet for each
of the R, G, and B filters.
[0075] Interestingly, another way of controlling the location (or
indeed area) of multiple droplets with respect to more than one
color filter within one `pixel` or cell of the display with the
minimum number of address lines leading to each `cell` would be to
employ the variable wetting patterning of the hydrophobic
substrate(s) discussed in this and the previous applications.
[0076] Thus, a single cell of the display, containing (for example)
two droplets functioning (say) as light-blocking droplets, could
have different voltages (respectively, for example with regard to
the potential applied to each end of each resistant electrode)
applied to each end of two different `zones`, within which there
would be one droplet contained within each zone by variable wetting
`energy barriers`. If all the colors in the visible light spectrum
were, for example, distributed in an appropriate layout across each
of the two zones, then by independently manipulating the voltage
differences supplied to each end/side of each resistant electrode,
it would be possible to achieve most, if not all, of the possible
color combinations with two droplets.
[0077] The ability to control the size of the droplet (by, for
example, increasing the electrical potential applied to
appropriately-positioned electrodes so as to increase the
`flattening` effect on the droplet by known electro hydrodynamic or
electrowetting means where, for example, the droplet is located
within another appropriate liquid) means that we could, if desired,
make an arrangement whereby there was one droplet adjacent to each
of (say) the three primary colors red, green and blue in such a
location as to block/obstruct (or filter, or use the `window`
approach described herein to allow controlled amounts of light to
pass through a droplet) a desired portion of the light passing from
that filter (or other light-modulating or frequency-changing
material or item) to a display screen, or to projected--or for
other light-modulating purposes.
[0078] By expanding or contracting these (e.g.) light-obstructing
droplets, we are able to determine the color of the light emerging
from the system.
[0079] FIG. 9 illustrates this principle. In this particular
example, one electrode is inserted into an electrically-conductive
liquid (an electrolyte) `surrounding` droplets (e.g., oil droplets)
with which the electrolyte is immiscible.
[0080] As the applied potential or voltage differential between
that of the electrode in contact with the electrolyte and that of
an electrode underneath the (hydrophobic) substrate is increased,
the droplet will `flatten` itself, as shown in the diagram below.
Of course, although the diagram below shows such an approach being
used in a light-emitting system, it could also be used in a
light-reflecting system--employing, for example, ambient light.
Equally, of course, this example of an electrolyte and oil droplets
could be replaced with polar droplets acting as the (for example)
light-blocking droplets--as is shown in prior art, including my own
US patent.
[0081] Thus, taking FIG. 9 as an example, if there were no light
sources underneath the lower substrate, but instead, the lower
substrate (or one or more surfaces underneath that substrate, if
the lower substrate were transparent or translucent) could be
light-reflecting, and the change in size (or in other approaches,
the location) of the (e.g.) light-obstructing droplets would serve
as a controllable means of modulating the respective intensities
(or other properties of light) of light able to pass onto, or be
reflected by, the respective different light-modulating elements in
question (in this example, red, green and blue color filters).
[0082] In the particular example given here, it is clear that
provided the (e.g.) black-colored droplet is at least largely
non-permeable by light--even when it is `flattened` by
electrowetting and/or other (e.g., electro hydrodynamic) droplet
shape-changing effects--then by dynamically modifying the profile
(and thus the liquid-solid contact area) of the droplets above each
of the 3 shown color filters, it is possible to control the amount
of the color that passes through the system onto or from each
filter--and thereby to control the color of light emerging from the
system. Clearly, as an alternative arrangement to that shown above,
the black droplets could have been any color or of any desired
light-modulating properties, and could for example alternatively
have been located beneath (in terms of the diagram) the color
filters, to achieve similar functionality.
[0083] As is well known to those skilled in the art, there are many
other methods and arrangements for changing the curvature of a
droplet surface, or the angle at which the droplet meets the
substrate beneath it, other than the arrangement shown above, which
is provided merely as an example of one possible system. (The
droplet could, for example, be electro hydrodynamically (including
by means of electrowetting effect) induced to move sideways along
the surface shown, thereby, for example, bringing it into contact
with an area of the substrate where a wetting pattern induces it to
spread itself more widely--thus, in this important example, the
permanent pre-treatment of the surface upon which the droplet moves
or changes shape is of different hydrophobic levels at different
locations along its surface; thus, if the droplet were induced due
to electrowetting effect to change location to a location where the
permanent hydrophobic level is relatively lower than the
surrounding areas, then the droplet could be caused to expand its
contact area with the surface at that location.
[0084] What is claimed here is any suitable means of changing the
location on a surface, or the total area of liquid-solid contact,
of a droplet by varying the electrical potential applied to one or
more electrodes proximate to that droplet (whether electrically
insulated from it, or with one or more other mutually-immiscible
liquid(s) or fluid(s) surrounding liquid it or not), where such a
change of location or area caused by electrowetting effect or other
electro-hydrodynamic means provides the means by which that change
will serve to modulate, in a controllable manner, the amplitude,
intensity, or other properties of light passing from one or more
light sources (including ambient light) onto one or more
light-modulating or frequency-converting items within a space
distribution of such elements which are incorporated within that
device.
[0085] It should be noted that the middle electrode in the FIG. 9
has a `hole` in it: this example of one possible arrangement or
shape for an electrode is provided simply to illustrate that,
optionally complimented by one or more suitably-positioned optical
lens (or lens arrays) [shown], a transparent electrode (such as
ITO, etc.) is not necessarily required.
[0086] In relation to electrodes, it should of course also be noted
that although FIG. 9 shows an electrode introduced into a second
liquid which is an electrolyte (where, for example, the location or
shape-changing droplet shown could be a non-polar liquid immiscible
from the electrolyte), this particular approach is only shown in
the diagram for illustrative purposes on one possible means of
applying the principles detailed herein: many other
well-established configurations of different one or more liquids
and differently-arranged electrodes--as shown in my existing US
patent, for example, and in other prior art could equally be
employed to achieve similar functionality. Thus, for example, there
could have been a ground electrode placed above or within the top
substrate, and the mobile liquid droplet could have been a polar
liquid--with, optionally, a non-polar liquid surrounding it.
[0087] In conclusion then, the purpose of the above discussion and
examples is to demonstrate a few of many possible arrangements
whereby the surface profile (i.e., the cross-sectional shape, or
the liquid-solid contact area), or location, of droplets in a
suitably-configured electrowetting or other electro-hydrodynamic
light-modulating device can be used to selectively block light from
passing onto, or controllably allow modulated amount of light to
pass onto, different elements are areas within a space distribution
of different light-modulating or light frequency-converting
elements or materials, so as to controllably modulate the color or
other properties of light emerging from such a light-modulating or
display device.
[0088] It should also be understood that while the diagrams
referred to above have shown droplets located above color filters,
and in turn illuminated from underneath, there are clearly many
other possible arrangements of the light source, filters and
droplets, the electrodes and addressing means, and the presence or
absence of light-reflecting surfaces, and the use or non-use of
time-distribution systems which employ the same principles as are
described here.
[0089] It should also be noted that light-blocking systems exampled
by some of the above drawings can also be used where the light
source is in front of the display, and a light-reflecting surface
is located, for example, behind the droplet array. Thus, for
example, in FIG. 9, above, by expanding or contracting droplet's
total area (as described above), the apparent color of a
multi-pixel array, when viewed from a certain minimum distance
necessary to allow the eye to perceive a `composite` color, and
from a suitable range of angles, can be controllably changed.
Finally, although black droplets have been used as an example of a
means of obstructing or absorbing light, such droplets could
alternatively be of any color or light-modulating material--e.g.,
they could have been light-reflecting, or of light
frequency-converting materials, or incorporating such materials
within their volume--whether in a uniform distribution, or
otherwise.
`Wobbling` Droplet Approach
[0090] In my earlier patent application, I described a
droplet-manipulation approach employing electrowetting effect where
by varying the electrical potential applied to two or more
different electrodes, it is possible to distort the shape of a
droplet--and therefore its light-diffracting properties. FIG. 10
shows one example of such an approach, as was shown in my existing
US patent on electrowetting devices.
[0091] It should be pointed out here that this `controlled
wobbling` of the droplet can be used not only in one axis, but also
in two axis, if desired, by, for example, `crossing the electrodes`
as explained elsewhere herein.
[0092] It should be understood, with reference to FIG. 10, that the
actual respective locations and positions of the elements within
the above drawings are given only to illustrate the principle being
introduced here--they are not intended to be accurate in any way.
It should also be understood, with reference to the marked areas to
the left and right-hand side of the droplet which are of higher
hydrophobic properties than the other surfaces with which the
droplet can come into contact, that clearly the materials employed
to achieve this higher hydrophobic property must be so
configured--in addition to the positioning of the electrodes shown,
crudely, as being underneath these areas--so that, optionally, said
areas retain some hydrophobic properties in respect of the droplet
notwithstanding whatever electrical potential is applied--thus,
they continue to `resist` the presence of the droplet above them,
even though a potential is applied to the adjacent electrode. Thus,
the adjacent electrode may, for example, be located further to the
left (in respect of the right-hand electrode) than is actually
shown in the diagram above--so that the hydrophobic properties of
the marked more hydrophobic areas continue to resist the presence
of the droplet above them.
[0093] Fundamentally the same approach can be used with a droplet
in a container, where we seek to change the curvature of the top
(and/or bottom) surface of a droplet or measure of liquid.
[0094] FIG. 11 shows one of many ways of achieving a purpose
similar to the diagram above, but where the electrodes are located
at the side of the container of the liquid. As in all the
electrowetting devices described in this document, the electrodes
shown would in EWOD approaches be electrically insulated from the
liquid shown--but this is not necessarily the only approach, and
this patent includes, in the case of all electrowetting devices
described herein, that such devices alternatively do not
incorporate an electrical insulator between such controlling
electrodes and any particular liquids.
[0095] In FIG. 11, I have shown resistant electrodes being
used--although clearly a similar effect could have been achieved
using a number of separately-addressable electrodes. It may be
assumed for the purposes of this diagram that the electrodes shown
at the right of the drawing are electrically insulated from those
on the left, and are in this example oppositely-poled.
[0096] If we assume that the electrodes to the right and left of
the liquid shown are resistant electrodes, then it will be
appreciated that by modulating the voltages applied to different
electrical connections to different locations on the respective
electrodes, the cross-sectional profile of the top surface of the
liquid, for example, can be controllably modulated.
[0097] It should be noted that an alternative to the system shown
in FIG. 11 would have been to have arranged one or more circular
resistant electrodes (like lengths of a hollow tube, within which
the liquid is contained, and where the liquid is electrically
insulated from the resistant electrode(s)). By this alternative
means, we would have been able to manipulate the cross-sectional
profile of the top surface of the liquid in a different axis. More
than one such ring-shaped resistant electrodes surrounding a liquid
could optionally be employed for many other possible
purposes--including for example to provide a means whereby elements
or particles (for example, light-refracting or light-reflecting
particles or optical instruments) located within the liquid could
change their location, orientation or angle due to modulation of
electrical fields created by the modulation of potentials applied
to different locations on different resistant electrodes such as
those shown in the diagram, thereby serving, for example, to
controllably modulate properties of light passing through the
liquid.
[0098] Clearly, the same approach can be taken where a solid lens
or other optical instrument `floats` on (in this example) the upper
surface of the liquid, as is illustrated in FIG. 12, for
example.
[0099] One application of the approach shown in FIG. 11, for
example, is to provide a dynamic light-modulating means employing
electrowetting effect--which could be used, for example, so that it
operates as a different kind of variable focal length lens than is
currently available. If both the top and bottom surfaces were
manipulated by means such as those described, then clearly the
optical potential of the device expands considerably!
[0100] In FIG. 11, the use of a resistant electrode also provides
another interesting possibility: namely, that of inducing by
electrowetting means one or more measures of liquid to move to
different locations within (for example) a tube. If there were, for
example, two separate measures of liquid subject to electrowetting
effect located within a tube with some distance between them, these
measures of liquid could be separately moved, or changed in shape
(and thus optical performance) with respect to each other. Thus for
example if the distance between the two droplets or measures of
liquid was changed by electrowetting effect, that would (among
other potential uses) thereby provide a new type of liquid zoom
lens arrangement. Of course, optionally, more than 2 separate (or
separately-addressable and mutually-immiscible) such measures of
liquid could be employed for additional functionality.
[0101] The focal length of the two different and separate measures
of liquid could be dynamically modulated by, for example, changing
the cross-sectional profile of their surfaces by the means
described here and in my existing US patent on electrowetting
devices, thereby enhancing the zoom/light-modulating capabilities
of such a system. The use of resistant electrodes in such a device
would be very attractive, as it would provide the means of achieve
the aforementioned functions without the need for a number of
different, separately-addressable electrodes to (for example)
induce the change of location of one or more measures of liquid
within such systems.
[0102] In this example, the surface of liquid may be simply convex,
but due to different electrowetting forces at play in the top and
lower sections of the drawing below (due to the different
voltages(s) applied to the different ends of the resistant
electrodes shown, as described elsewhere herein), the lens could be
controllably `tilted` at different angles by the employment of
electrowetting effect and biasing techniques such as are described
in my existing US patent on electrowetting devices.
[0103] Clearly such `tilting` techniques can be far more
sophisticated that merely tilting in one axis, as is implied by the
drawings below. More separately-addressable electrodes, for
example, could have been provided in the `sleeve` around the
container shown in the drawings above and below here--or of course
a resistant electrode approach could have operated in two axes,
instead of the one axis approach shown here.
[0104] FIG. 12 shows a similar device to that shown in FIG. 11--but
with a solid lens being additionally supplied to the system. For
the purpose only of illustration of one or many possible
applications of such a system, a multicolored filter has been added
to the drawing--so as, for example, to change the color of light
departing from such a system.
[0105] The particular design shown here suggests that any light
source employed in a system similar to this one shown would be
located beneath the container shown. However, clearly there are
almost innumerable possible arrangements of lenses, reflectors or
other optical instruments (with for example the latter two classes
replacing the lens shown) which could exploit this basic idea.
[0106] If we stay with the instrument being a lens, and a
multi-colored filter being the two elements in the system (instead
of innumerable other elements exploiting the same principle would
could optionally have been employed instead of these two items) as
an example, the multi-colored filter could optionally have been
located below the liquid container shown, and a reflective surface
located beneath that, so that it then would becomes a reflective
display. (Obviously, the container shown is purely to illustrate
the principle here--in this particular example, the container might
be extremely shallow to increase its performance for this
particular function).
[0107] Or as just one of so many other possible employments of the
same principle, the system shown above could be located above each
of a number of differently-colored filters--say, R, G B--so that by
tilting the lenses, different portions of the light passing through
the filters from, say, a light source beneath the filters would be
allowed to pass on to the display screen--the remainder being
diverted on paths which would not reach the screen. And so on.
[0108] Equally of course, with other optical instruments or items
within or on the surface of the liquid, different effects could be
caused to take place by employment of the same fundamental
idea--for example, if the solid lens shown in the drawing were
instead a light-reflective element--e.g., a mirror--and the light
source was instead above the device, then clearly the incoming
light could be reflected at different angles onto other optical
instruments--e.g., color filters, other reflectors or lens, prisms,
etc.--or simply back out to the world.
[0109] As with all of the light-modulating devices discussed in
this document, the use of such terms as `color filters` is only
used for the purposes of example: as I have stated many times
before within this article, any space distribution or distribution
of any light-modulating or light-frequency converting elements or
materials may alternatively be employed, with the change of
light-modulating properties caused, directly or indirectly, by
electrowetting effect being caused to change the location,
orientation, angle or other suchlike light-modulating effects of
solid optical instruments on the surface of, or within, a liquid
subject to electrowetting effect are included within the scope and
claims of this patent application. Equally, the term optical
instrument can include any kind of such instrument--e.g., it might
be a prism, for example.
The Use of One or More Lenses Trapped at the Interface Between Two
Fluids
[0110] One additional, optional approach would be to employ a solid
lens or other optical instrument (e.g., one or more
light-reflecting surfaces) trapped at the interface between two
fluids which are mutually-immiscible, and at least one of which is
subject to influence by electrowetting effect. Thus, by changing
the shape, disposition or location of one or more such liquids in
contact with another liquid by electrowetting effect, such an
optical instrument trapped between two such liquids--for example,
due to the respective different densities of the two liquids, the
optical instrument may be changed in its attitude or performance
due to it being forced to accord with said changes of shape or
disposition of one or more of said liquids.
Solid optical Lenses Located Inside, or on the Surface or, Fluid
Droplets
[0111] As has already been discussed, one alternative to simply
using droplets which are changed in shape or location by
electrowetting or other electro-hydrodynamic forces is the use of a
lens (or item able to function as a lens), or other optical
instrument such as a reflector, prism, etc., composed of a solid
material such as transparent plastic positioned either within, or
on the surface of, a fluid droplet.
[0112] Taking as one possible example the case of a transparent
plastic or glass sphere, it will be appreciated that, using a
suitable fluid and (for example) a transparent sphere of
appropriate refractive indexes and surface tensions,
[0113] (1) the sphere could be retained inside the droplet by,
among other factors, the surface tension on the droplet's outside
surface; and
[0114] (2) the sphere can, if so designed, perform an optically
very predictable light-refracting function without significant
optical distortion by the droplet within which it is located.
[0115] It will further be appreciated that, optionally, the
lens-like solid particle, lens or other suitable optical item may
be so shaped as to reduce any tendency for it to change its
location or orientation within the droplet--which motion could, for
example, otherwise have undermine its optical integrity and
consistency.
[0116] Another possible function of the solid optical instrument
(e.g., a suitably-shaped lens) located inside a droplet would be to
assist in maintaining the desired curvature of the droplet--and
thus helping to determine the refractive index of the droplet--by
being so designed that the top surface of the lens lay close to,
and roughly parallel with, the surface of the droplet.
[0117] Thus, the purpose here could be to achieve a higher degree
of optical performance--in terms of predictably and accurately
focussing or directing light onto a multi-colored light filter, for
example--than could be achieved--or could be easily achieved--by
only using a droplet to perform that light-refracting (or
reflecting) function.
[0118] FIG. 13 shows such an example of one of many possible
different electronic and lens-positioning/design configurations
employing this `lens in droplet` approach. Note that the term
`hydrophobic polymer substrates` is only provided as one example of
materials and arrangements. Of course the material need not
necessarily be polymer, for example, and not both inside surfaces
necessarily need to be hydrophobic in respect of the liquid shown.
Similarly, there are of course--as is shown in my existing patent
and other prior art--many other possible electrowetting device
arrangements and configurations that could be employed. As with all
the diagrams in this patent application, the drawings are supplied
simply to illustrate the principle being introduced--and in no way
suggest that the particular configuration is the preferred route
amongst so many possible ways of employing the same principle.
[0119] Clearly, aside from the many other possible electrical
arrangements of such a system to achieve a `droplet+lens` movement,
other possible optical arrangements could position the lens in
other positions in respect of the droplet--e.g., resting on the top
surface of the lens. Clearly, in the particular design shown, the
electrodes would probably be transparent--e.g., made of ITO.
[0120] FIG. 14 shows a similar design to that of FIG. 13, but here
the droplet, or measure of liquid, has a flat top (thus undermining
its capabilities in functioning as a lens, for example), and the
diffracting function may be performed solely by the solid lens
within the droplet. (The elements of multi-colored filter, light
source, etc. are included here merely to remind the reader of one
of the many ways that the droplet can be used to direct light onto
selected locations or zones of any space distribution of different
light-modulating properties, or different light
frequency-converting materials or items).
[0121] Of course, many other possible configurations employing
different elements of the design shown could employ the same
principles as those shown here, but achieve similar functionality
with such different arrangements, or could achieve quite different
functionality--e.g., the lower substrate could be light-reflective,
and the light source could come from above the system in FIG. 13:
e.g., it could be ambient light, with the lens focussing light onto
a color filter, for example, located within the lower substrate,
and thereby performing a similar `color-selecting` function. Other
lenses, not shown, are clearly possible.
[0122] [Incidentally, in most of the designs herein, and in the
previous patent applications, such factors as collimating the light
derived from a light source are not mentioned, although they are
important for some of the designs--the reason being simply that the
lens systems incorporated within these inventions do not constitute
the inventive elements of these applications--and their design
constraints and features are well-known to those skilled in the
art. Methods of collimation are well-known to those skilled in the
art.
[0123] In respect of all the diagrams in this patent application,
it should be remembered that configurations and arrangements shown
only represent demonstrations of a small number of the many
possible different configurations and arrangements: for
convenience, for example, light is generally shown as coming from
the bottom of the diagram--though it could just as easily come from
the top; equally, in most cases, systems depending upon reflected
light--whether ambient or otherwise--can equally employ variations
of arrangements shown herein where such is not the case.
[0124] With reference, then, to FIG. 14, the key point is that
because the droplet within which the lens is located has a
flattened top, it may therefore perform no refractive function--the
refraction function thus being left to the lens within the droplet.
Clearly, this `flat-topped droplet` approach could also be used
with many other approaches outlined herein and in the previous
applications.
[0125] Similarly, the fact that a different electrode arrangement
is shown in FIG. 14 is not specifically relevant to the point of
the drawing and the associated design principles: it is merely used
to remind the reader that many different electronics arrangements
and configurations are possible to achieve the controlled
displacement of the droplet to achieve the desired color
change.
[0126] The reference in FIG. 14 to resistant electrodes with a hole
in each is, similarly, just a reminder of different configurations
possible in the designs, and is not intended to be specifically
relevant to that particular droplet arrangement. The intention is
simply to remind the reader that electrodes might be made of
transparent or translucent conductive material, or they might be
non-transparent materials--e.g., copper--with a slot, or hole in
their design to allow light to pass through the areas it must pass
through to allow the system to function. If a `slot` is used, for
example, the system design might be such that the droplet can only
move along one axis--with a corresponding multi-color filter array
(for example) arranged so that light focussed by the solid lens
focuses onto different color(s) as the droplet is moved from one
end of its range to the other end.
[0127] FIG. 15 provides another example of a design approach
whereby it is the solid lens, rather than the droplet, or the
droplet combined with the solid lens, that is responsible for the
diffraction of light in the system. In this drawing, a second
liquid, immiscible with the droplet, surrounds the droplet.
Provided that the refractive index of said second liquid is similar
to that of the droplet fluid, then it will be appreciated that the
solid lens within the droplet may be the only light-refracting
element between the two substrates. Such an approach might, for
example, be used where the liquid droplet is composed of a polar
liquid, and the surrounding liquid is a non-polar liquid. In this
as in all other designs and ideas provided within this document,
where more than one measures of liquid are in contact with each
other, typically they will be mutually-immiscible.
[0128] It is noteworthy that one of a number of important potential
advantages of locating a solid lens within the droplet includes the
diminishing or removal of potential problems associated with
ensuring a proper `lens-like` curvature of the top surface of a
droplet not incorporating a solid lens, if the system design were
to permit the droplet to be flattened at the top surface by contact
with the upper polymer substrate: clearly, if a solid lens is
located within the droplet, for example, its optical performance as
a lens would not be undermined by such a situation.
[0129] Although the lens shown has a shape which enhances its
shape-conformity with the top surface of the droplet shown, any
shape of lens-performing item may be employed, with accordingly
different performance results, and concomitant potential advantages
and disadvantages. Similarly, once again, it should be remembered
that in all these drawings and descriptions, where a solid lens is
used in a drawing or a description, it could just as well have been
a light-reflecting or other light-refracting element, or any other
light-modulating or light frequency converting instrument or
material that was employed instead of such a lens.
[0130] Also noteworthy is that although one attractive way of
employing this `solid lens in/on droplet` approach is for the
purposes of controllably moving the droplet sideways, and thereby
directing light onto different colors within a multi-colored filter
array, it would also be possible to employ the same approach where
a droplet is being made `flatter` or more bulbous by electrowetting
means affecting the angle between the droplet and the surface it is
touching, or increasing the field strength acting on the
droplet--and a solid lens is located within, or on the surface of,
a droplet being thus made flatter or more bulbous.
[0131] Clearly, one potential use of this approach would be as a
focussing, or `zoom lens` tool (depending on the configuration of
other lenses), where the solid lens is simply being raised or
lowered by the change in the profile of the droplet. Another
potential use would be to provide a variable focal length lens by
providing one or more additional solid lens at appropriate other
positions in respect of the `lens in droplet`.
[0132] FIG. 16 gives a simplified illustration of this type of
approach, where the distance between the two solid lenses shown
varies according to the controllable variation of the
voltage/polarity of the electric charge delivered to (in this
particular layout) two different electrodes, as the droplet causes
the solid `lens in droplet` to rise and fall.
[0133] It will be appreciated that in the above diagram, simplified
for the purposes of showing the principle of this approach, light
(advantageously, collimated) passes through a first lens (or lens
system) which is permanently located in that position; it then
passes through the lens located within the droplet and then onwards
towards, for example, a display screen--or one or more further
lenses to expand the light paths to fill the pixel size at the
screen front. Clearly, additional lenses may be located above, as
well as below, the droplet, depending upon the objectives of the
particular system. Equally, although a transparent substrate is
shown acting as a `window` above the droplet, in certain design
approaches that `window` could simply be a hole in the
substrate.
[0134] In this drawing, the green-outlined droplet represents the
droplet in a bulbous profile configuration (i.e., the surface upon
which it is located is hydrophobic in respect of the liquid), and
the red-outlined droplet represents one possible profile when, for
example, electrowetting/effect exerts a `flattening` effect on the
droplet profile. The choice of liquid for the droplet would,
obviously, be determined by the particular droplet
shape-manipulation method being used, as well the need for an
appropriate diffraction index to suit the particular optical
arrangement, and to avoid optically disrupting the function of the
`lens in droplet` unless so desired. (Thus, for example, the
droplet might, as previously discussed, actually be located within
a 2nd liquid of similar refractive index). For the sake of an
example, the droplet being manipulated could be a polar, or
conductive, droplet--and the 2nd liquid could be a
mutually-immiscible non-polar liquid.
[0135] The point marked `A` is one possible position of the solid
lens when the droplet is `flattened` (i.e., spread over a larger
area), as shown by the red-outlined droplet. The solid lens has,
thus, dropped down in the drawing, thereby shortening the distance
between itself and the permanently-positioned lens shown below the
lower substrate.
[0136] Another, optional, approach would be to `tilt` the angle of
solid lens in the droplet by causing the droplet to `bulge up` at
one side more than at the other--e.g., to bias the system. Examples
of methods of achieving this effect have been discussed in existing
patent application, and in other prior art. A similar purpose could
be achieved with a `lens in droplet` approach--but with the
additional potential advantage of perhaps better optical
performance from the `lens in droplet` than could be achieved with
only the droplet.
[0137] It should be noted that while only one `level` of system is
shown in the above drawing, it will be appreciated that--as is the
case with many of the electrowetting systems described in this
document) multiple duplications of the `lens in droplet` approach
could be used, so that more than one solid lens is controllably
movable--either vertically (e.g., so as to increase or decrease the
distance between the solid lenses within droplets), or laterally
(which could, for example, achieve a greater diffraction of light
paths by a smaller distance movement of one or more lenses within
droplets).
[0138] Similarly, though no physical `walls` are shown in the above
or other drawings which would restrict lenses within droplets (or
indeed droplets themselves) in their scope of physical movement,
these are clearly feasible, and in certain
applications/configurations, could be used advantageously. These
walls, or barriers, need not in all applications be solid, but may
instead restrict, for example, a solid lens within a droplet from
moving laterally, whilst allowing the fluid within which it is
located to flow freely, so as, for example, to restrict the solid
optical instrument so that it remains properly positioned to
perform its optical task in relation to other lenses or optical
instruments, including color filter arrays. Such `permeable walls`
are shown in FIG. 17.
[0139] In examples like this, other suitable means may be added to
enhance the stability of the optical instrument--in this case, the
solid lens--so that it does not become destabilised by making
contact with the walls surrounding it. One means of achieving this
is to ensure that the surface tension differential between the
inner surface of the `walls` within which the lens is located, and
the liquid itself, is suitably calibrated so that the solid optical
instrument will be constrained by said surface tension differential
from touching the sides of the `tube` within which it is
located.
[0140] Optionally, magnetic fields produced by fixed-position,
permanent magnets could be used to help retain optical elements,
which would be magnetised, in their desired location.
[0141] It should also be pointed out that while with some
applications of the `lens in/on droplet` approach, the objective
would be to make, insofar as is feasible, the fluid droplet to be
`optically invisible` in terms of its diffractive index allowing
the solid lens to be the only light-diffracting element in the
droplet, other approaches could potentially take the opposite
approach, and employ the diffractive qualities of both the `lens in
droplet` and the droplet itself.
[0142] This patent application includes within its scope the use of
other light path-changing optical instruments--such as prisms,
reflectors, etc.--where their affect on the passage and routes of
light passing through the system is controllably altered by
changing the shape, position or orientation of the droplet. Thus,
as a simple example, a hinged diffractive or reflective element
which `floated` on the top of droplet, and was secured at one side
to a permanently-located design element so that it changed its
angle (for example) to the horizontal, or its orientation, as the
droplet moved or changed its profile or shape, would fall within
the scope of this application.
[0143] Similarly, multiple solid lenses--e.g., a solid lens
array--which `floated` within or on the surface of one or more
droplets whose position, shape, profile or area was controllably
varied by methods discussed in this or my previous application,
would also fall within the terms of this patent application.
[0144] FIG. 18 shows a simplified illustration of one means of
executing such an approach.
[0145] In FIG. 18, we see one of many possible arrangements whereby
the `sideways` movement of a droplet can be used as an actuator
means to move a lenticular or other lens array, or
light-diffracting or light-reflecting array or color filter array,
sideways--and thereby change the color or image emerging from the
system. Such a system could of course be used in 2-axis, so that a
`floating` microlens array could be controllably moved both
North-South, and East-West (figuratively speaking) in respect of
other, fixed-position lenses or lens or reflector arrays.
[0146] As with all the other diagrams herein, the above drawing is
only meant to focus on the particular idea in question--and thereby
in this case, for example, one or more possible arrangements of the
electrodes, etc. are not shown, as these are discussed elsewhere in
this and my previous applications, and in many cases are well-known
to those skilled in the art.
[0147] It will be understood that in respect of the above drawing,
the use of the electrowetting means of moving droplets already
discussed, as well as other droplet-moving means already known to
those skilled in the art, provides a useful means of moving the
lenticular array from side to side (for example) so that the array
may focus light onto differently-colored light filters on the
filter array shown above the lens array.
[0148] By this means, of course, different colors or images may be
controllably caused to emerge from the system. If the above light
filter array were, for example, in fact a series of pictures
compressed in the normal manner used in `lenticular photographs`,
then it will be appreciated that a series of different `frames`
showing different images contained within the `composite
photograph` would be shown.
[0149] It will be appreciated that many other droplet-moving
arrangements are possible to achieve a similar result, using the
same principles--such as, for example, using more than one droplet
to influence the position of the lens array, so that, for example,
the lens or reflective array `rides` on a number of droplets.
Similarly, it will be understood that the positions of the lens and
filter array could easily be reversed, so that the position or
`posture` of the droplet(s) are instead moving the light filter or
composite photograph or image, and the lens array be fixed in
position. And so on.
[0150] Clearly, a similar approach can be taken to moving one lens
array in respect of another. Such lens arrays may, optionally, be
microlens arrays.
[0151] The reason why this approach is particularly interesting is
that it potential presents an actuation means for varying the
configuration of optical elements within a display without having
to use existing actuators such as piezoceramics, etc., which often
are either too expensive, or require high voltage, or suffer from
other disadvantages such as very small `stroke`.
[0152] Apart from the well-known (to those skilled in the art, as
revealed in existing prior art) means of `flattening` or making
more `bulbous` the profile of a droplet or measure of liquid,
another interesting technique is to manipulate a droplet's total
area is to move it laterally--employing techniques already
discussed in -this and my former patent applications--onto areas of
pre-treated surface(s) with different wetting patterns that the
droplet is in contact with, so that the droplet will change its
profile (=total area) due to the different surface wetting patterns
of the polymer surfaces to which it is displaced.
[0153] FIG. 18 shows one of many possible arrangements employing
this principle. The top half of the illustration shows a view of a
substrate bearing a droplet from above; the lower half shows the
same substrate from the viewpoint of the human eye at right
(shown). Although a resistant electrode is the preferred means of
controlling such a device, alternatively a plurality of
separately-addressable electrodes could be employed to achieve
similar functionality.
[0154] The turquoise area represents an area of greater
wettability, or wetting. That area is surrounded by an area of less
wettability--e.g., it might be ultrahydrophobic. A gradient of
hydrophobicity may optionally be employed to induce the droplet to
move from one end to the other of the area within the
ultra-hydrophobic boundaries.
[0155] In the drawing, we can see that, from right to left, the
width of the area within the droplet can move decreases: this
forces the droplet to become more `bulbous` as it moves from right
to left due to electrowetting effect--thus changing its optical
performance, or focal length.
[0156] Optionally, if the above system were to be used in a display
system, one or more optical lenses could be used in the above
example to compensate for the lateral movement of the drop in
respect of its position within the total `cell` area in a
display--so that, for example, light rays passing through such a
droplet are progressively `diffracted towards the centre of the
`pixel` at the screen itself, as the droplet is moved progressive
further from the centre of said pixel, or `cell`.
[0157] Clearly, this is only a simplified illustration to
demonstrate a point: namely, that suitable patterning of wetting
and non-wetting on the substrate surface, together with
suitably-positioned and configured electrodes, can be used as a
means of controllably changing the cross-sectional profile, or to
change the area of solid-liquid interface--and thus change the
optical performance of the droplet.
[0158] Such an approach can be used in an almost infinite number of
different ways to change one or more droplet's optical performance
as it/they are moved along the surface of a substrate. Thus, for
example, this technique could be used to change the focal length of
a droplet functioning as a lens, or to change the reflective
performance of the droplet's surface if it were serving to reflect
light, and so on. Clearly, if this system were duplicated `one on
top of the other` so that (say) two substrates bearing droplets
were above each other, and were moved so that, for example, they
stay above each other in the path of light, then they might change
their shapes in similar or different ways as they moved (say) to
the left--thereby changing their combined optical effects on light
passing through or onto them.
[0159] Clearly, optionally, one or more droplets could bear solid
lenses or other optical instruments within or on their
surfaces.
[0160] It should be pointed out that this type of technique can be
used to cause droplets to move to positions which are not within
the strongest field (or most wettable areas) close to them--but are
`as close as they can get` in view of the wetting patterns to which
they are subject.
Florescent `Doping` of Droplets
[0161] It should be pointed out that in any appropriate
droplet-employing display or color filter means such as those
disclosed herein or in my previous patent applications, the
droplets can optionally be `doped` with fluorescent material which
convert UV, for example, into visible light of different colors
(depending upon the frequency-converting, or `down-converting`
materials employed. In this way, whether using UV-emitting light
source(s) or ambient light, a high brightness can be emitted by the
droplets. Such systems can also employ reflective surfaces to
reflect ambient light, and can also employ systems exploiting
internal reflections within a transparent solid material such as
plastic together with the droplets.
The Use of Droplet-Using Display Means as a Dynamic Color Filter
Control Means
[0162] As has been pointed out in my earlier patent applications,
the various droplet-manipulating systems discussed can be used for
applications beside electronic displays. For instance, the same or
similar techniques can be used to provide a
dynamically-controllable color filter means, instead of displaying
visual information in the conventional sense.
[0163] Examples of such applications include placing a
droplet-using array in front of one or more light source(s) so as
to change the color of the emerging light for such purposes as
concert or theatre lighting, underwater swimming pool lighting,
shop lighting, etc.
[0164] Equally, many if not all of the systems and design
principles described herein can be used for the purposes of optical
signalling--e.g., for fibber optics communications--or any other
light-modulating purposes.
Color-Changing Walls, Screens, etc.
[0165] One possible application of the droplet displays/filter
described is to block light, or uniformly change its color, across
an array or surface. Thus, a glass screen around a shower could
employ the droplet approach to cause the glass screen to change
from transparent or translucent to (e.g.) black or another color
when someone is showering, for their privacy.
[0166] The same methods can be used wherever it is desired to
uniformly. (or non-uniformly) change the color, or render
non-transparent, an entire surface--be it an (e.g.)
transparent/translucent screen or wall, or the surface of a
product, etc. Thus, for example, the surface of a mobile phone case
could be changed to a desired color, or pattern, if any appropriate
one of the droplet systems already disclosed is located at or
beneath the surface of the case of a product (assuming a
transparent case where the droplet system is located beneath the
outer surface).
[0167] It should be pointed but it is possible to `pump` droplets
progressively across a transparent or translucent
medium--preferably where there are at least two layers of the
material, so that the droplets can be moved in the gap between the
layers. Techniques for moving droplets of liquids can include any
combination of those described in this, or my previous
applications, but with the change that instead of merely moving the
droplet back and forth (as in the case of the `moving liquid lens`
type of approaches), in this case we would be `passing` the droplet
from one pair of electrodes to another, so as to progressively move
the droplet to its target `destination`. Such droplets, for
example, could be of different colors, or possess other different
light-modulating properties.
[0168] Optionally, any of my invented droplet-moving systems can
incorporate `feedback` systems to enable the controlling
microprocessor to monitor the current position of droplets, and to
apply appropriate voltages to appropriately-located electrodes so
as to move the droplet by electrowetting means to a new position
from that current position. One of many possible technology means
of achieving such feedback on droplet location across an arrays
would be capacitive sensing used between two or more electrodes
within the system: different readings would indicate the presence,
or absence, of a droplet, and, indeed, could be used to derive such
information as the color of, for example, a certain pixel by
determining the droplet's current position.
[0169] By this means, a `glass wall` or glass screen, for example,
can be caused to either change color, or to change from opaque to
non-opaque, for example, by moving droplets in an interstice
between layers within the transparent or translucent item in
question.
Droplet-Based `Camera` (`Ejected Image-Bearing Substrate`)
System
[0170] It is possible, using many of the droplet-using display
systems and approaches discussed herein or in the previous
applications, or combinations thereof, to make a system which will
take a digital photograph` using any suitable optical sensor array
system--e.g. CCD, CMOS array, etc--and then use that data to adjust
a multi-pixel droplet display mounted on a suitable substrate(s)
composed of one or more layers, so that the display on said
substrate represents, within the limits of the droplet system used,
represents the image recorded by the optical sensor array--and then
to `lock` that display (if necessary, in the case of `volatile`
droplet systems) so that it becomes non-volatile, and then to eject
the image-bearing substrate(s)/film from the camera. The ejected
substrate thus would function similarly to a photograph, or printed
sheet of plastic or paper, etc., in displaying a representation of
the recorded image.
[0171] FIG. 20 shows, in schematic terms, one means of achieving
this.
[0172] Equally, it is possible to so arrange said substrate and its
component elements and electrical connections to the camera system
so that that the `photograph` (as described above) can be re-used
to display another, different image, and then to be again ejected
or removed from the camera. To achieve this, the `photograph` could
be inserted into a suitably-designed device similar to the device
described above, which would re-connect the image-bearing
substrate(s) to the addressing hardware, to then `unlock` the
droplet-positioning system if necessary by any suitable means, and
then to repeat the process described above.
[0173] The only essential difference between this approach and
other described above it is that instead of the display means being
a screen system permanently connected to a microprocessor and other
hardware, with the approach outlined above, the display means,
incorporating one or more (probably multi-layered) substrate(s) or
film, and employing whatever arrangement of droplets, second liquid
(optional), electrodes, address lines, etc. that is applicable to
the particular droplet display system chosen, can be detachable
from the image-collecting and (optionally) the processing and/or
addressing hardware. Clearly, if microprocessors, CMOS optical
arrays and the like in the future become sufficiently low-cost, the
ejected image-bearing substrate might incorporate one or more of
such elements permanently on-board the image-bearing substrate--so
that, for example, a `flat camera` with incorporated image display
would be feasible.
[0174] Clearly, a similar approach can be taken without the use of
an optical image array, where instead an image, or other text
(etc.) data is transmitted by any suitable means (e.g., direct
electrical connection, RJF, optically, etc.) to hardware connected
to a droplet-based display system, which then uses the received
data to configure the display at each pixel, or cell, of the
display, and then the image-bearing substrate is released from the
suitable elements of the microprocessor/hardware equipment, so that
the image-bearing substrate is as low-cost as is feasible--thus
potentially providing a `printing` system, for example, where the
`printed material` could be re-used to carry different
text/images.
[0175] It should also be noted that with the ever-decreasing cost
of optical arrays, microprocessors, etc., a device may be feasible
quite soon which employs an image-gathering means such as a CMOS
array, a microprocessor, memory facility, conductive address lines,
multi-layer substrates, droplets, power source etc. on a single
flat device--so that, for example, a device approximately the size
of a credit card could incorporate all of the above, and display an
image of whatever the optical image-gathering array is pointed
at.
PCB-Mounted Droplet-Employing Display Systems
[0176] Clearly, droplet-employing flat-screen color display systems
such as are discussed herein and in my previous applications have
the potential for being applied to many unique new product
missions--perhaps particularly because many of said display systems
can be light-reflective (i.e., employ ambient light to be read, and
thus require little electric power.
[0177] As just one or so many possible examples to illustrate this
point, such display systems could be mounted directly onto PCBs and
the like, thereby potentially achieving substantial economies for
manufacturers of electronic devices benefiting from a low-cost,
on-board display means.
Uniform Color Across a Droplet-Employing Display System
[0178] Clearly, there are many product or technology missions where
only a color change is required across an area (i.e., a
representation of text or images is not needed), and thus
individual addressing of each pixel, or `cell` is similarly not
required. If, for example, the function of the droplet-employing
`screen display` is merely to change the color of a product's outer
case (or portion of it), then substantial economies can be obtained
by arranging the addressing system so that all pixels, or cells,
are addressed in common--as if, in effect, they were all one pixel.
Using such an approach (often together with a reflective layer
beneath the droplets) the color of many every day objects such as
phones, computer monitor cases, cars, credit cards, wall paper,
dynamic light filters for lamps, etc., etc.
[0179] Equally, it may be that the requirements of the display
system fall somewhere between an individually-addressable `matrix
pattern` pixel system on the one hand, and a uniform color on the
other. Perhaps--as a somewhat poor example which nevertheless
illustrates the point--color-changing wallpaper bearing multiple
images of fleur de lys may require that the fleur de lys will all
be the same color (but that their color is adjustable), and that
the `background` color `behind` them is also addressed as a single
entity. This example is only supplied to illustrate the point that
in some cases, there is no point in providing an addressing system
able to address a vast number of individual pixels of equal size,
equally distributed in matrix array, when actually only a far
smaller number of `pixels` (all the fleur de lys may be addressed
as one) are required. Thus, each fleur de Lys may optionally
incorporate a large number of droplets which are addressed as
one.
[0180] Similarly, traffic signs with multiple possible messages to
be displayed could have the different text and/or graphic patterns
arranged as `icons` with single address systems (rather than
addressing multiple pixels within each message). (Like the examples
above, this could employ any of my proposed droplet-using display
approaches).
[0181] As a simple example, a traffic sign with the graphic
messages `No entry` and `One Way Street` for display at different
times of the day, if the particular droplet approach was
transparent droplets (possibly fluorescent-doped) with a
light-reflective surface, then one approach would simply be to
arrange the droplets as though they were a lenticular array--thus
by moving them, they would cause light to be directed onto one of
the two possible images. If, however, that approach were not
desired, then electrodes could be positioned so as to create both
display--and either one set of electrodes would be charged, or the
other one would.
[0182] It should be pointed out that `uniform color droplet arrays`
can also advantageously be used to control the color of the
backlighting for other display technologies--e.g., LCD--allowing
the user of a device to themselves determine what backlighting
color they want within a vast array of possible colors.
The Use of Any Electrowetting Effect-Driven Light-Modulating
Droplet System with Stationary Cameras or Other Optical Sensors
[0183] If the location or shape of a measure of liquid subject to
electrowetting effect is manipulated by electrowetting effect so
that said change of shape or location serves to change properties
of light passing into a camera--whether conventional or
digital--then clearly this can be used as a means of achieving some
of the functionality of having a movable camera (or other optical
sensor) where the camera itself remains stationary. Many of the
droplet-manipulation systems described herein, or in my existing US
patent (or indeed any other electrowetting droplet manipulation
system) may be employed, together with a camera or other optical
sensing device, to achieve this purpose.
[0184] I claim as my invention any electronically-controlled
display system employing measures of liquid which are changed in
shape or location by electrowetting effect to controllably direct,
or control the amplitude or other properties of light which pass
onto or through any space distribution of different
light-modulating or different light frequency converting elements,
items or materials for the purposes of controllably modulating
properties of light emerging from such a system.
Multiple Droplets within Single `Pixels` or `Cells`, and Cell Wall
Design
[0185] There are many circumstances where it may be advantageous to
provide a number of droplets within a `cell` or pixel, instead of
providing only one droplet within one separately-addressable cell
or pixel.
[0186] One of many possible reasons why multiple droplets within
cells can be advantageous is related to gravity: generally
speaking, and depending upon the particular design of the system in
question, as droplets get bigger, then become less subject to
electrostatic forces, and more subject to gravitational
sources.
[0187] Thus, it may in many circumstances be attractive to provide
a number of small (e.g., 10-50 microns diameter) droplets within a
single `cell`, which will therefore (apart from other
considerations) be less subject to being accidentally displaced
from their correct position, or indeed to being displaced from
their own cell altogether, by a large physical shock being applied
to the screen system (when it's dropped, for example), if `walls`
between cells are not used.
[0188] Thus, a single display cell might look like any of the
droplet display systems shown herein and in my previous
applications--but duplicated several times, with common address
lines leading to electrodes (generally speaking) insulated from,
but close to, each individual droplet.
[0189] FIG. 21 shows one single `cell` of one possible arrangement
for a droplet display system. In this particular arrangement, which
is simplified and not to scale, and is chosen merely for the
purposes of example, we see a backlit layout, employing resistant
electrodes with different voltages applied to each electrode end
beneath the lower substrate, and simple electrodes shown above the
upper substrate. The address lines are shown to illustrate the
point that the upper and lower electrode `sets` are addressed in
common--i.e., there are in effect only 3 separate address lines
here.
[0190] I have also added in markers indicating ultrahydrophobic
areas to delimit the scope of movement (in droplet-displacing
approaches) of the droplets, and to keep them separate. Obviously,
the drawing is not to scale--as otherwise the droplets could hardly
move!
Wetting Patterns Used to Retain Droplets in a Desired Position.
[0191] With many of the droplet systems discussed herein, and in my
previous applications, it is advantageous that the droplet(s),
having been moved to a target location, should stay in that
location until a different performance (e.g., color variation) is
required of them--at which time they will again be moved. A
non-volatile display system, where the droplets do not require an
electric charge to hold them in a certain position, is clearly
advantageous.
[0192] Provided that droplets are sufficiently small, electrostatic
forces will in many circumstances be quite adequate for retaining
droplets in their `targeted` locations. However, one means of
assisting in maintaining the position of a droplet that is in
contact with one or more substrates or surfaces is to provide a
pattern of different wetting properties on the surfaces with which
droplets may come into contact so that a certain amount of
energy--which preferably is unlikely to be exerted other than by
the application of electrical energy to appropriate electrodes
proximate to the droplets--is required to be applied to the droplet
in order to move it from any position.
[0193] There are many possible patterning approaches for the
distribution of differentially wetted surfaces to achieve such a
`movement inhibiting` function. The main point is that by
presenting the droplet with a series of `energy barriers` provided
by surfaces that are unwetted relative to other adjacent surfaces,
the droplet must have sufficient energy applied to it to overcome
the resistance that that energy barrier presents.
[0194] Thus, in a simple example where the droplet's scope of
movement is only along a straight line from position A to position
B, if there are a series of suitably-configured and suitably-sized
and shaped such energy barriers presented to it along that line,
these will act to inhibit the movement of the droplet from its
assigned location.
[0195] If, on the other hand, the droplet is permitted to move in
more than one axis, then a pattern of lines, or gradients, of
wetted and relatively unwetted surfaces can serve to similarly
inhibit droplet movement. Whilst in many cases these could take the
shape of straight or curved zones across the substrate surface,
there are many alternative patterning approaches--including, for
example, `dots` with hydrophilic properties so that the droplet
will tend to `centre` itself over such small filled circles unless
appropriate electrical power is applied to adjacent electrodes.
[0196] Clearly, the ideal level of such `energy barriers` is that
they are the minimum necessary to prevent accidental (i.e., droplet
movement not dictated by the electronic droplet control system)
movement, while requiring only the minimum energy necessary to
induce the droplets to `climb over` such barriers--e.g., the
voltage applied to proximate electrodes is sufficient to overcome
the `resistance` of the `energy barriers`--when such a movement is
required of the display system.
[0197] I claim, in addition to the above, the use of relatively
high hydrophobic levels in certain areas to act as `borders`--i.e.,
to act as energy barriers to delimit the scope of movement of one
or more droplets to the area--e.g., a cell, or pixel--within which
they are designed to be able to move.
Meniscus/Liquid Surface Profile-Distortion Dynamic Color
Filtering/Screen Display Approaches
[0198] Whereas many of the optical display and dynamic color
filtering approaches discussed herein and in my published US patent
on electrowetting displays, applications have related to liquid
droplets being moved or shape-manipulated in what could be termed
`open` environments--i.e., where the droplets are not constrained
on all sides--similar approaches can be used with liquids located
within tubes and other containers.
[0199] As is well known, the shape of the top and bottom surface
meniscuses of a droplet in a tube can be made to be convex or
concave by providing a suitable surface tension differential
between the inside surfaces of the tube and the surface tension of
the droplet liquid itself. For this reason, it is possible for a
droplet to function as an optical lens--the optical refractive
index of which can be controlled by modulation of the aforesaid
absolute and comparative surface tension levels.
[0200] Similarly, using the techniques shown herein and in my
existing US patent, it has been shown that droplets can be induced
to move by various different approaches employing, generally,
electro hydrodynamic forces--in particular, electrowetting
effect--induced by various different arrangements of electrodes and
different types of liquids (e.g., polar and non-polar liquids).
[0201] FIG. 22 shows a simple example of one such possible
arrangement, where a tube is used instead of, for example, a couple
of hydrophobic substrates with a droplet in between them.
[0202] Here we see a droplet of appropriate dielectric properties
located within a tube, which we may assume here incorporates on its
inner surface a hydrophobic material, and is in most (but not all)
possible approaches there will be an electrical insulating layer
between the electrodes and the liquid--with the hydrophobic layer
closest to the liquid.
[0203] In this particular example, the inner walls of the tube are
pre-treated--as explained in other examples herein--so as to make
(in this particular example) the wetting properties lowest towards
the top, with progressively increasing wettability further down the
tube. However, this is only one strictly optional approach.
[0204] Outside the tube is located, (in this example), two
electrodes, each occupying, as it were, one hemisphere of the
`sleeve` around the tube, insulated from each other. One electrode
is a resistant electrode; occupying the other half of the `sleeve`
is a counter-electrode. (Obviously, there are many other possible
arrangements, including laterally-oriented and
separately-addressable `rings` of electrodes [which may optionally
be resistant electrodes], either separately addressable, or
addressable as `sets` of electrodes which are separately
addressable, which can then be used to controllably induce the
droplets to move up and down the tube, or to change their
shape).
[0205] In this example employing a resistant electrode where we are
modulating the difference of potential between one electrode and
the other at different points along the length of the resistant
electrode by modulating the voltage applied to different points on
the resistant electrode (and thereby modulating the location and
value of one or more electric field being applied between the
electrodes--thereby modulating the hydrophobic properties of a
surface with which the droplet is in contact).
[0206] The voltage applied to address line A may be, for example,
15 V, and the potential delivered to the other electrode may be
zero volts (purely for the sake of example to illustrate the
principle here).
[0207] In the absence of suitable electrical potential being
applied to the electrodes, the droplet might lie at the bottom of
the tube due to gravity; with sufficient and suitable electrical
charges applied at points A and B, and C, the resulting electro
hydrodynamic forces can induce the droplet to controllably move up
and down the tube. Optionally of course, there may be two or more
liquids present--for example the droplet shown may be of a polar
liquid, and there may be a second, non-polar liquid with which it
is mutually-immiscible present as well. In some cases it may be
advantageous to use liquids of similar density or specific gravity,
so as to offset some effects of gravity, if so desired.
[0208] At the bottom of the drawing is shown a fixed-location lens.
Beneath this lens might, for example, be a light source, or a
light-reflective layer, depending on whether this system is used
for backlit, or reflective display, purposes (if it is, of course,
a display system at all; it could be any kind of light-modulating
device).
[0209] It will be appreciated that by controllably moving the
droplet up and down the tube, a focussing function, or variable
focal length optical system, can be achieved. Clearly, an array of
such devices as are shown in this diagram could be arranged in an
array alongside each other, for example, to provide multi-cell
similar or different optical performance. Whilst the principles
above can be used at many different scales, such an array might
prove particularly attractive on a very small scale--say, for
example, where the droplet size might be 20-200 microns in
diameter, and the system is contained within two or more
substrates, at least one of them being transparent.
[0210] Also notable is the observation that by electrically
changing the electrowetting/electro hydrodynamic forces acting on
the droplet, both the curvature of the top and bottom faces can be
changed, as well as the distance between the top and bottom--with
the consequent changes in optical performance of the droplet.
[0211] As a further development of this approach, it will be
appreciated that it would be possible to have more than one mobile
droplet in such a `tube` as is shown above (e.g., one able to
operate in the upper half, and another limited to the bottom
half)--thereby providing, for example, the potential for a flat
array of `zoom lens` capability in each `cell`. In such a scenario,
there may optionally be provided more than one resistant
electrode--for example, one to control each of two droplets.
[0212] Optionally, a solid optical instrument such as a lens,
reflector, etc. could be located within one or more droplet of such
systems, if desired.
Solid Multicolored Filter within a Droplet
[0213] It should be pointed out that apart from the other optical
instruments--lens, reflector, etc.--that may be located within or
on the surface of a droplet, a multi-colored light filter could
alternatively be used. In addition to the other control means
already discussed, its orientation or location--and this applies
also to any of the other alternative optical instruments--could as
an alternative to the methods described elsewhere herein optionally
be controlled or influenced by an electric field, or
electromagnetic or magnetic field, applied for example by the use
of one or more resistant electrodes located adjacent to, but
preferably insulated from, the droplet.
`Window` Droplet in Combination with a 2nd Mutually-Immiscible
Droplet of Different Light-Modulating or Light-Transmitting
Properties
[0214] It is simply impossible to list all the different--or even
the primary--possible ways and arrangements to exploit the droplet
moving/manipulating techniques I have described in this and
previous patent applications. However, I will outline the following
`different` approach simply to show that what may seem to be
`different` from the arrangements I have discussed hitherto is
really still simply yet another alternative way of applying the
same principles as I have already described.
[0215] [Note: I have labelled the following diagrams used to
illustrate this principle with (a), (b) and (c) suffixes to the
previous diagram's number, simply to continue the sequence of
figure numbers. There is no other significance to this labelling of
these figures, and it does not imply any particular relationship
with the previous drawing--FIG. 22].
[0216] FIGS. 22(a), 22(b) and 22(c)
[0217] In this `windows` approach (as I shall call it), one or more
transparent, or translucent, or light-transmitting, droplets are
located within a light-obscuring/blocking/reflective (or at least
less, or differently, light-transmitting than the 1st droplet) 2nd
measure of liquid. For the sake of example, the 1st (window)
droplet might be a polar liquid, and the 2nd droplet might be a
non-polar liquid.
[0218] The `window` droplet is moved around on a hydrophobic
surface to different locations, or is changed in its shape or size,
by the employment of electrowetting effect, in any of the ways
already discussed with respect to methods of moving or changing the
shape of partially or entirely light-obstructing (`black droplets,
in the above descriptions) or light filtering droplets in this
document, or by any of the well-known methods of achieving this
function by electrowetting effect, which are well-documented in my
existing US patent on electrowetting displays, and in other prior
art.
[0219] FIG. 22 (a): the circular items marked 1, 2 and 3 represent
three different light-modulating, or light frequency converting
(e.g., `down converting`) items or materials within a space
distribution of such items or materials.
[0220] The circle marked `droplet outline` represents the outer
perimeter of the `window droplet` which is being changed in its
shape or location on a hydrophobic substrate, due to electrowetting
effect.
[0221] The dotted oval shape represents a possible area of the
second liquid, with which the 1st liquid is mutually immiscible.
This might be a non-polar liquid such as oil, with the 1st liquid
being a polar liquid, for example.
[0222] It will be understood that if for example the 2nd liquid
were black, or light-reflecting, and if we imagine that the marked
different light-modulating items 1, 2 and 3 were color light
filters, for example, then in the state shown in (a), light would
pass through the first, translucent/transparent droplet onto the
colors 1, 2 and 3--but with most of the light passing onto/through
the colors represented by 1 and 2.
[0223] I have inserted the letter A simply to indicate that this
area might, for example, be simply a transparent area (in a
light-transmitting version of the device)--or in a light-reflecting
version, it might be reflective or simply white. Using time
distribution techniques, it would in some configurations of this
device be useful to modulate the proportion of time `spent` on this
area A, so as to modulate the brightness, or intensity, of the
perceived color, for example, of the light which emerges from the
system.
[0224] In 22 (b), we see that the droplet has been moved to a new
location by electrowetting effect--thus changing (for example) the
color balance of the light which emerges from the system, due to
the fact that the light passing through the window droplet is now
passing onto different items/colors within the space-distribution
of different light-modulating items.
[0225] In 22 (c), we see that now the size of the droplet (i.e.,
its contact area with the hydrophobic surface upon which it is
moving) has increased. This represents an addition tool in
providing a wide range of light-modulating capabilities from this
device.
[0226] In 22 (d), we see a cross-sectional view of the (e.g.,
polar) window droplet located `within` the 2nd (e.g. non-polar)
measure of liquid. The many possible arrangements of electrodes in
this system are not shown, as they have been widely described in my
existing US electrowetting patent, and in this document, and in
other prior art. It will be appreciated from this drawing that if
we wanted to cause the `window` to stop operating, then it would be
possible, with suitable droplet size and suitable distance between
top and bottom enclosing surfaces, to achieve this by simply
`flattening` the window droplet sufficiently using established
electrowetting means to achieve this with sufficient electrical
potential causing the lower hydrophobic layer in contact with the
droplet to become sufficiently hydrophilic.
[0227] In 22 (e), we see a plan (from above) view of the window
droplet located together with the second liquid. 1 and 2 are
provided simply to illustrate that the droplet may be changed in
both location and shape, if desired.
[0228] It should be noted, incidentally, that of course there might
be provided more than 2 types of liquid (in most cases,
mutually-immiscible), and equally of course there might be more
than one `window` droplet within a system--thereby, for example,
providing the means of simultaneously directing light to two or
more different locations within said space distribution of
different light-modulating or frequency-converting items, filters
or materials.
[0229] It should also be noted that, if desired, electrode
arrangements, and the electrical potential delivered to those
electrodes, can be made so as to modulate the hydrophobic
properties of both the upper and the lower inner surfaces in
contact with the window droplet. For example, if both surfaces were
very hydrophilic, the droplet could be caused to be very `spread`
on both top and bottom surfaces, and very narrow in the `neck`
between the top and bottom liquid-solid contact areas, in
cross-sectional terms.
[0230] As has been pointed out many times in this article, the
capabilities of this approach are extremely wide, as the particular
items onto which we choose to selectively direct light is almost
unlimited--they may be different colors, or different optical
instruments, or other light-modulating surfaces or items, or they
may be different frequency converting materials. Thus, if UV, or
near-UV light were being emitted by one or more light sources
incorporated within the device, then clearly we would be able to
modulate the colors of light which emerged from the system by
exciting different such materials to different extents at different
times by allowing the UV light to pass onto them.
[0231] If these two liquids are located within two substrates or
layers of material, and if (in most possible configurations) the
window droplet extends from `top` to `bottom` of its volume from
the inner surface of the top substrate to the inner surface of the
lower substrate, then it will be appreciated that this droplet can
act as a light path permitting light to pass through it.
[0232] In a light-transmitting version of this device (depending
upon where the light source(s) were located), both top and bottom
substrates enclosing the liquids on the upper and lower sides might
be transparent, or at least translucent. Thus there might, for
example, be a light source located below the device (in
cross-sectional terms), so that the light is directed upwards, and
passes through the `window` droplet, and onto particular filters or
other light-modulating or frequency-converting materials or items,
depending upon the location or shape of the window droplet at any
time.
[0233] Equally of course, the lower substrate might be
light-reflecting--or there might be one or more light-reflecting
items or surfaces located beneath (in cross-sectional terms) the
lower substrate, if it was translucent. In this configuration, the
space distribution of the items that light will reach through the
window droplet may be located beneath the lower substrate. Thus, it
will be appreciated that this device could be used, for example, as
a light-reflecting display means using ambient light--or as a
light-transmitting display means. Of course, its capabilities are
not limited to display, and extend in scope to any application
requiring dynamic light-modulating capabilities.
[0234] It will be understood that any light-filtering, or
light-reflective surface(s) located `below` the system (in
light-reflecting mode, as described above) might comprise graphics,
or lettering, in some arrangements or particular applications.
Thus, if for example, the word `Ricardo` was printed on a substrate
beneath (in cross-sectional terms) the window device described, and
if the window droplet were transparent, and the 2nd measure of
liquid was dyed black, then as the droplet was moved over the area
showing the word `Ricardo`, the observer would see that portion of
that word which was revealed through the window droplet. Thus, this
system represents a totally novel means of selectively displaying
selected amounts of visual information or graphics or the like, and
clearly has many applications in displays and signage.
[0235] Thus, in summary, this device is a `moving hole` acting as a
dynamic light path to allow light to pass onto selected locations
of a space distribution of different light-modulating or light
frequency-converting items--and then out towards the outside world,
having been modulated as desired by the system.
[0236] The purpose of this approach is to allow light to pass
through the 1st droplet or measure of liquid, but to control the
amplitude, intensity or other properties of light which passes
through the first liquid and then passes onto, for example,
differently-colored light filters, or a space distribution of
different light-modulating or light frequency-converting materials,
so as to controllably change the color, amplitude, intensity, or
other properties of light which emerges from this light-modulating
system by means of employing electrowetting effect to change the
liquid-solid contact area, or the droplet's shape (in plan, or
cross-sectional terms), or to change it's location in respect of
different locations or areas or items or elements within a space
distribution of different light-modulating filters or items, or a
space distribution of different light-frequency converting (e.g.,
`down-converting`) materials.
[0237] The purpose of these transparent droplets is to act as
`windows` within the (e.g., black-dyed) 2nd liquid. The transparent
droplets (though they may not necessarily be transparent--but they
must at least be translucent to some extent), thus, may not need to
function as lenses, but may instead merely function as windows
allowing light to flow through the 1st droplet, and to pass onto or
through selected filters or light-modulating or
frequency-converting elements, materials or items, for the purpose
of providing an innovative light-modulating means--which could, for
example, be used as a screen display or light projection system, or
an optical signal switching/modulation system, or any of many other
light modulating applications where dynamic modulation of
properties of light are required.
[0238] Clearly, the controlled movement of such transparent
`windows` provides many different means of, for example,
controlling the color of light emerging from the system. Such
transparent droplets could, of course, alternatively have a `flat
top` (thus different from droplets functioning as a lens) or could
alternatively function as a liquid lens. The droplet would be
manipulated in shape or location on a hydrophobic surface by
electrowetting means such as are described herein, in my existing
US patent on electrowetting devices, or in other prior art on
electrowetting devices.
[0239] Of course, many of the other droplet shape and size
manipulations techniques discussed in this and the previous
applications can also be applied to the above approach--e.g.,
transparent `window` droplets expanding/shrinking in total area
above respective color filters or other light-modulating or
frequency-converting filters, items or materials, and so on.
Equally, solid optical elements within droplets--e.g., a light
obstructing or light-reflecting particles, items or elements--could
be manipulated or moved within a transparent or translucent droplet
which is acting as a `window` to permit the passage of light. And
so on.
[0240] It should be appreciated that the above `window` approach
can also be used as a type of dynamically-controllable diaphragm
(for example, for use in a camera to control the amount of light
which is permitted to pass through the 1st droplet--e.g. by using
electrowetting effect to increase or decrease the solid-liquid
contact area), to control the amount of light permitted to pass
through a light-transmitting/transparent or translucent or
light-transmitting measure of liquid.
[0241] This could simply take the form of electrowetting effect
being used to change the area of the droplet in contact with a
hydrophobic surface--thereby increasing the size of the
`window`--or it could also take the form of the droplet acting as a
window being caused by electrowetting effect to change location on
a surface with respect to different areas or locations, or items or
elements which have different light-modulating or light
frequency-converting properties, so that the light passing through
the droplet (which would be surrounded by a second liquid with
relatively less, or zero, light-transmitting capabilities) passes
onto or through filters or other light-modulating items which
themselves serve to reduce the amplitude or intensity (or other
light-modulating properties) of that light.
[0242] It should be understood that the only requirement here is
that the light-transmitting properties of the first measure of
liquid are higher than the second--or that the 1st liquid provides
better optical properties (e.g., in terms of allowing more light to
pass through it, or in terms of distorting images or the passage of
light less than the 2nd liquid) than the 2nd measure of liquid.
[0243] An illustration of how wide the applications of this
approach are may be provided with this example: the 1st liquid may
be totally transparent, without any significant light or
image-distorting properties; the 2nd liquid may also be
translucent--but may have a somewhat `misty` appearance to the
human eye, rather like a bathroom window or a glass shower
enclosure might have, for example. Such an approach could be used,
for example, as an attractive and subtle dynamic visual display
means--such as on the window of a restaurant, where the transparent
1st liquid droplets could display a graphic design (e.g., a bottle
of wine) which would be transparent, allowing an observer to see
through the wine bottle shape--but where the 2nd liquid would be
sufficiently opaque to allow the observer to distinguish the wine
bottle shape (or lettering, or whatever) when observing the
restaurant window. Such a wine bottle shape might, for example, be
made up of many different pixels or cells, each containing two
liquids such as are described here.
[0244] Finally, it should be remembered that the window droplet may
be of any color, or any light-modulating properties--i.e., not
being limited to being transparent, and colorless--and this is also
true of the 2nd liquid discussed.
[0245] A different angle on this general approach would be that a
droplet caused by electrowetting effect to increase or reduce its
contact area with a surface with which it is in contact, or to
change its location on a hydrophobic surface, may be composed of,
or may incorporate within its volume, one or more light
frequency-converting materials. The change in the droplet's contact
area with the substrate could then serve to increase or reduce the
amplitude of light of particular colors emitted by such (e.g.)
`down-converting` materials when excited by, for example,
ultra-violet or near-UV frequencies of light from an adjacent light
source emitting those frequencies.
Use of Droplets to Change Internal or External Reflection
[0246] In my earlier patent application I pointed out that droplets
moving on transparent surfaces can be used to change light paths by
changing the internal (or external) reflection properties of the
surface they are moving on, and to thereby cause light which would
otherwise have been reflected off the other side of that substrate,
or surface, from the side occupied by the droplet, to instead pass
through it.
[0247] The sketch below serves to remind the reader of this
technique, and to point out that many of my droplet systems, or
derivates thereof, can be used in this way, or in combination with
this approach, to provide a display or light projection means (as a
simple example, the light path shown could be diverted through one
or more color light filters). In certain cases, particularly where
ambient or artificially-generated UV light is provided as a light
source, such droplets may be dosed with a UV fluorescent dye.
Alternatively, of course, such droplets may be dyed with one or
more colors.
The Use of Droplets to Reflect/Deflect Light
[0248] While some of this document, and the patent applications by
me which preceded it, have been concerned with the use of droplets
to refract light. I have, however, often pointed out that
reflecting, or deflecting light off the surfaces of droplets is
equally feasible--and is included within my claims, and is
applicable to any of the design approaches suggested here.
[0249] means of achieving this are almost innumerable--but they
would largely rely upon manipulating the shape (profile) or
position of a droplet so that the angle at which light arrives at
the surface of a droplet can be varied so as to either reflect it,
or not reflect it--or, of course, to modulate the angle of
reflection from the droplet so that, for example, the light passes
through different alternative color filters, or different points on
a filter array, or other light-modulating or frequency-converting
items.
The Use of Lasers with Droplets
[0250] Clearly, lasers, being merely a different form of light, can
be used together with many of the droplet systems contained in this
and my previous applications, and are thus contained within the
claims for protection that I make. Clearly, many of the devices
described herein would be suitable, for example, for optical
signalling and communication means, as well as for modulating
properties of the light from a laser being directed into systems
described herein.
Systems Described Herein, and in my Previous Patent Applications,
Being Used as Optical Switches
[0251] It will be readily appreciated that although I have mainly
concerned myself with the use of my droplet manipulation and
displacing techniques described in this and previous patent
applications being used for display and dynamic light filter
applications, they clearly can also be used for many
applications--all of which I consider to fall within the scope of
my patent applications. For example, they may be used as optical
switches, since they potentially have the capability of providing
an economic means of rapidly changing the quality, color or
amplitude of light passing onto or through the droplets, or items
contained on or in the droplets--thereby providing potential for
being either an analog or digital switching means.
Systems Described Herein, and in my Previous Patent Applications,
Being Used as Dynamic Light Filters
[0252] I have pointed out in my existing US electrowetting patent
concerning droplet manipulation that the droplet systems described
therein and herein can, in many cases, be applied to dynamically
changing the color projected from a droplet-employing system--e.g.,
the color of light emitted by a lamp of suitable type and
configuration, just as they may be used as a screen display
means--but I would repeat that statement to apply to the systems
described herein. Equally, many systems described herein could be
used to modify other properties of light emitted from a lamp or
similar device--for example, for changing the angle, or angle of
distribution, of such light passing through the devices described
herein.
Use of any Droplet Systems in Reflective, as Well as Transmissive,
Mode
[0253] As I have mentioned in my existing US electrowetting patent,
many of my proposed droplet systems--or other suchlike systems
employing similar fimdamental approaches--can be used either as
reflective displays or as displays relying on a light-transmitting
means associated with them--using backlighting, for example.
Multi-Level Droplet Systems
[0254] I claim as my invention any practical combination of any
droplet-using display or dynamic light-filtering device approaches
described or implied herein, or in my previous applications
relating to droplet-moving stems. Thus, for example, multi-level
droplet systems would be included within the claims of this patent.
(By `multi-level`, I mean droplet-using display or projection
systems where more than one of my proposed approaches are used `in
parallel`--e.g., one above the other. Thus, if the system shown in
FIG. 14 were duplicated underneath it, so that the droplets in each
system moved independently or together, that would comprise one
example of a `multi-level system`.
Droplets Dyed with Multiple Colors
[0255] It should be noted, for the avoidance of doubt, that many of
the droplet moving and/or distorting systems described in this and
the previous applications can employ droplets which contain one or
more colors--e.g., dyes. Thus, a single `droplet` may in fact
incorporate, for example, only one color, or many different colors
across its volume or area, so that by exposing different colors to
light paths by electrowetting means, different filtering effects
take place.
The Term `Liquid` in these Applications
[0256] The term `liquid` in this and previous of my applications
should be taken to include, as appropriate to each device and
system, fluids including gases, air, gels, and the like. Thus, for
example, droplets incorporating many colors within them may
actually be closer to gels than to, say, glycol or water.
Color Combining `Solid` Optical Instruments within, or on the
Surface of, Droplets
[0257] It is noteworthy that the term `optical instruments` in the
context of lenses, reflectors, prisms, etc. objects within or on
droplets can include optical devices designed so that, rather than
(for example) focussing light on a particular color within the
visible spectrum as a standard lens does, an alternative
manifestation of the same principles could simultaneously focus or
direct light from the light source onto more than different point
or area on a color filter array, and thereby `combine` colors onto
the display screen.
Addressing on `Sets` of Electrodes to `Pump` Droplets Across
Surfaces
[0258] Already discussed are many different types of electrode
arrangements. Although I have often used `resistant electrode-type`
arrangements, this is in no way to suggest that multiple different
electrodes are unlikely to be used. Similarly, I have often simply
only drawn one counter-electrode, or earth plane, on the other
sides of illustrations. This does not mean that there would
necessarily only be one counter-electrode opposite multiple
electrodes on the other `side` of the system--it is simply that
this is not the focus of matters under discussion, as the
principles behind, and the means of achieving, the displacement
and/or distortion of droplets are well known to those skilled in
the art, and constantly varying the number of electrodes here or
there would simply be likely to distract the reader from the points
at hand.
[0259] Both of these features have in fact quite a lot to do with
speed of drawing, and with keeping the drawing simple so as to
focus attention on particular points being currently discussed,
than to suggest that one system is always preferable to another--or
even that the particular arrangement of electrodes is even sensible
or feasible in each case. Another reason for not spending much time
or space in these documents on showing different possible electrode
layouts is simply that such knowledge is widely known to those
skilled in the art, and there is no point in repeating options that
are obvious and well-known to those skilled in the art.
[0260] Notwithstanding the above, it is perhaps worth pointing out
the following, for the avoidance of doubt. Just because a `cell` in
a display has many different electrodes, that does not mean, of
course, that each electrode needs to be separately addressed. One
of the reasons for the attractiveness in certain systems of using
one or more resistant electrodes is to keep to a minimum the number
of address lines leading to each cell, or pixel, or the display,
whilst still retaining the ability to move or distort a droplet
with a high degree of exactitude, rather than to be limited to a
certain number of `stop positions` along substrate, for example,
which could be the case with a simple arrangement of a few
electrodes underneath the (e.g.) hydrophobic polymer substrate.
[0261] In FIG. 24, the droplet is currently located roughly above
and between a red and a yellow electrode lying beneath the
hydrophobic surface of the lower substrate. The point here is that
we can move the droplet to the right by applying appropriate
electrical potential--as described already herein, and in earlier
patent applications by me--to each of the colored sets--without
needing to have a separate address line to each of the individual
electrodes. Clearly, with reference to the above diagram, there
could alternatively be a number of droplets located within the
above shown array, instead of only one. It should be remembered
that, if necessary, suitable `feedback` systems can be incorporated
into the system to provide real-time monitoring of the
location/posture of droplets, so as, for example, to `pump` them
along a surface such as that shown, containing many different
electrodes which are nevertheless only addressed by a relatively
small number of address lines.
Physical Indentations as Alternative `Droplet Braking`
Technique
[0262] Elsewhere herein I have discussed the use of patterns of
hydrophobic/hydrophilic material to help retain droplets in the
positions to which they have been moved by the electronic control
system.
[0263] A simple alternative or complementary approach to this is
the use of physical indentations, which may be arranged in
patterns, to restrict the movement of droplets. Thus, instead of,
or complementary with, an unwetted `energy barrier` on one or more
substrates with which the droplet may come into contact, an
addition physical ridge may be used on one or more of said
substrates to enhance the `movement retarding` techniques available
to retain droplets in desired positions. Advantageously, the
position and shape characteristics of such `ridges` would be
designed so as to avoid disrupting any applicable light paths,
etc.
An Alternative to the `Resistant Electrode` Approach Already
Discussed
[0264] A further tool in the armoury (so to speak) or controlling
techniques applicable to droplet systems is that of an electrode
which is so shaped that it is wider at one end, or at one or more
points along its length, or across its surface, than it is in one
or more other places, so that the electric field generated by said
electrode (in combination with some counter-electrode) is greater
where its surface area is wider than elsewhere.
[0265] A single address line, for example, may be attached to an
electrode which (say) is long and narrow, but which becomes
progressively wider at one end. This shape will, in the absence of
other contradictory factors, cause a greater electric field to
exist at the wider end than at the narrower end when the electrode
is appropriately charged.
[0266] Clearly whilst it will not be possible (or at least, not
sensible) to change the fixed shape of that electrode--and it thus
does not have the dynamically-changeability of the `resistant
electrode approach`--the use of an electrode shaped as described
above is nevertheless a useful tool, if combined with, for example,
a similarly-shaped electrode which is reversed in position so that
the second's wide end is opposite, and parallel to, the first's
narrow end.
[0267] It will be appreciated that if the two electrodes are part
of a droplet-controlling system such as those discussed herein, and
are suitably positioned and configured to be able to influence the
droplet's position, then by modulating the voltage applied to
single address lines attached to each of the two electrodes
(respectively), the droplet can be caused to controllably move back
and forth as the position of the strongest electric field, and/or
the strongest electrowetting influences, is controllably moved
between the two electrodes.
`Tilting` or Rotating Solid optical Instruments within or on
Droplets by `Tilting` the Electric Field
[0268] It should be noted here that dipole techniques can be
applied to tilt the angle (related to the top and bottom
substrates, for example), or to cause the rotation, of a solid
optical instrument which is located within, or on the surface of, a
droplet.
[0269] FIG. 25 shows the fundamentals of a dipole-type
electric-field controlled rotating or droplet system--which can be
configured in so many different ways there is little point in
specifying one or another approaches, as the principles of rotating
or tilting a dipole item located within an electric field, and
causing it to move in response to changes in that electric field,
are so well known. However, in the context of the droplet-type
systems that I have described, there are some new, and rather
interesting, possibilities.
[0270] The optical item located in the droplet might have any
feasible function--a lens, reflector, etc. It might bear different
colors on different areas of its surface, and of course there are
many possible locations for fixed position lenses which are not
shown here to be located. I have also ignored many other questions,
such as the fact that the droplet shown would be rather unlikely to
keep its position in the centre of the droplet--and so on. These
problems, and many possible solutions to them, are well-known to
those skilled in the art and do not require rehearsing here.
[0271] There are some interesting ideas to be noted in connection
with the above approach:
[0272] Firstly, that the droplet, and the optical item within it,
can be so configured to be effectively separately-addressable.
Thus, we can move the droplet in one direction or the other (this
is not necessarily required in all possible approaches); and we can
separately dictate the tilt, or rotational orientation, of the
optical item within the droplet by applying different fields
strengths, types, or field orientations by applying different
voltages and polarities to the different electrodes.
[0273] The many different possible means of achieving the
production of such fields are well-known, and the location and size
of electrodes shown above should not be interpreted literally at
all--they are merely there to shown that we have a number of
separately-addressable electrodes above and below, and insulated
from, the droplet and the item within it.
[0274] Since we clearly can separately control the droplet and the
optical item within, various possibilities, however, arise:
[0275] The optical item could be a lens: light would pass onto and
through it to one or more different colored filters, and then
onward, for example, to the display screen. (Electrodes A and E,
for example, could be charged with an appropriate to tilt the item
as shown), though clearly it would seem advisable for the
electrodes to be far closer together if that were the case, since
moving the droplet itself might not be required
[0276] The optical item could have differently-colored surfaces on
the outside, and by rotating, tilting or twisting it, could display
different colors or surfaces to the outside world on a screen.
[0277] The optical item could be a reflector, so that light passing
onto it is controllably reflected onto differently-colored light
filters--and then onwards to the screen display.
Permanent Magnets+Electro Hydrodynamic Droplet Displacement
[0278] If one or more permanent magnets were permanently positioned
in appropriate locations vis-a-vis the optical item within/on a
droplet, and if said optical item were subject to magnetic forces
associated with said permanent magnets, or magnetised elements,
then clearly the act of moving the droplet to the left or right
could cause the optical item to tilt and/or rotate accordingly.
(For example, if the spheres in the drawing above were instead
magnetised, for example, with North and South poles replacing the
`+` and `-` signs shown.
[0279] As an example: for the sake of simplicity, imagine that a
magnet or magnetised material is located within or near the bottom
substrate in the above drawing. If the magnet's North pole were
facing upwards, and the optical item were currently located above
and slightly to the left of that magnet's North pole, then as the
droplet--and thus the optical item within--is drawn by electro
hydrodynamic forces progressively to the right (say, by charging
electrodes B and E) the magnetised optical item would
then--assuming suitable design of the component parts of the
system--be induced to progressively rotate so that its South pole
constantly faced towards the magnet's North pole. Thus, in effect,
a `rolling` effect would be seen, with the optical item rotating
clockwise until it moved out of the magnet's effective field.
[0280] Clearly, a potentially useful display system could be
created using fundamentally this approach, whether the optical item
were multi-colored on its outside, or was a lens as described
above, or a reflector. It has to be said that the system would, in
some applications of, or particular execution methods of this
approach, have to incorporate suitable means of coping with the
fact that the optical item was itself moving sideways. That
wouldn't matter if the lens were simply a sphere that would operate
similarly regardless of its orientation--thus directing light onto
differently colored filters, for example--but it could in certain
designs matter if our purpose was to rotate the magnetised sphere
to expose different colors on its outside.
[0281] Clearly, however, the magnets and electrodes could be far
closer together and smaller than the illustration above in order to
minimise that sideways movement, and lens systems, mirrors and
other devices--including even another droplet which `followed` its
movements on a separate substrate pair--could certainly be devised
to cope with this movement of the optical item.
[0282] Indeed, the system could if desired be modified to be
either:
[0283] (a) more than one magnetised `optical elements`--e.g.,
spheres--within each droplet, each bearing two or more colors or
differently-reflective surfaces, so that by moving the droplet
sideways, the (say) black or white-colored hemispheres of the
spheres would be facing in the same orientation--say, upwards,
towards the outside world--or
[0284] (b) a single sphere or other magnetised item, bearing at
least two different colors on its surface, located within each
single droplet (say, as part of a large number of such `magnetised
item within droplet`--configured droplets), each droplet being
moved sideways by electro hydrodynamic or any other suitable
droplet-moving system.
[0285] (b) first, it might look something like FIG. 26.
[0286] In this drawing, we see 3 stages (from top to bottom) of the
movement of the right-hand solid sphere, the surface of which is
divided into two halves for color purposes (black and white).
Clearly, electro hydrodynamic forces, acting in ways already
discussed herein, will be created by the appropriate charging of
the electrodes shown as yellow rectangles, and these forces can,
(as shown in the marked stage `2`) induce the droplet, and the
solid sphere within it, to move to the right.
[0287] Located in or on the lower substrate in this example are
shown the magnetic poles of one or more magnets, or magnetised
elements (of course it might be one magnet, with respective poles
shown).
[0288] The sphere is magnetised with a North and South Pole.
Provided that the surface tensions of the droplet and the sphere
are suitably configured, when the droplet is moved towards the
right by electro hydrodynamic/electro wetting forces exerted by the
electrodes, the sphere is forced to move with it. As it does so, it
is forced to rotate to align its magnetic poles to conform to the
magnetic fields generated by the two magnetic poles shown buried in
the lower substrate. As it rotates, the color perceived by an
observer looking from above the system changes.
[0289] Thus, in stage `1` in the above drawing, the sphere's upper
face is black. By the time it reaches its extreme right-hand
position, it has rotated through 180 degrees, and its upper surface
is now white.
[0290] Clearly, here we have the fundamentals of a rather
interesting display system. As with most, if not all, of the
drawings in this application, the particular arrangements of
elements--electrodes, address lines, presence or absence of
fixed-location lenses, etc., etc.--should not be taken as in any
way prescriptive or limiting: on the contrary, this approach can be
used in almost innumerable different configurations, both for black
and white, and in color, etc., displays. It should also,
incidentally, be remembered that this system could optionally be
used, for example, in a 2-axis control system, instead of the
one-axis approach shown above: this offers the potential for
`rolling` a ball covered with different colors in any direction, in
order to expose the desired color to view. One or more
permanently-located optical lenses may optionally be used to
magnify the image of the portion of the outside surface of the
sphere which it is desired should be displayed.
[0291] I claim as my invention any electronically-controlled
droplet-moving display system which employs electro hydrodynamic
forces to move droplets containing, or bearing, optical elements
which are magnetised, where said movement of said droplet and the
optical element(s) within causes said the optical elements to
change their orientation and/or optical performance as a result of
being exposed to changes in local magnetic fields generated by one
or more permanent magnets appropriately located within the
system.
[0292] Clearly, the optical elements could instead have been many
other possible optical devices--including lenses or reflectors, for
example, which are caused to tilt by the droplets containing them
being moved sideways, and magnetic forces acting on them
consequently changing, and tilting or rotating them; equally,
instead of only black and white hemispheres, a multitude of
different colors could be located on the outside surface of the
spheres, with, optionally, fixed lenses located, for example, on
the upper substrate so as to magnify the image of the
upward--facing color on the spheres.
[0293] Whilst there are almost innumerable different ways of
exploiting this combination of permanent magnetic fields and
electro hydrodynamic displacement, or shape-distortion, of
droplets, it is notable that potential `technology mission`
application areas for such display approaches are almost equally
numerous: so-called `electronic ink` would certainly appear to be
one of them, bearing in mind the non-volatile potential for this
system, and the potentially wide viewing angle that could be
achieved with appropriate design approaches.
[0294] FIG. 27 illustrates how, as another possible use of this
approach, a lens could be tilted--obviously, the angles, electrode
positions and size, etc. are not to be taken literally.
[0295] It is notable that the above system can be used in 2 axis
rather than the one shown above--so that, for example, a tiny
sideways movement in one direction may cause the sphere to `spin`
in more than one axis, thereby displaying a different color to the
outside world--whether directly, or through optical instruments
such as reflectors, lenses, etc.
[0296] Equally, the lens shown above could instead have been a
light-blocking element--so that it could be, for example, tilted to
allow a smaller of greater amount of light (either in total, or in
respect of particular light filters, and thus particular colors) to
be allowed through the system.
[0297] It should also be observed that the permanent magnets shown
could easily be replaced with, or complimented by, one or more
electromagnet--and the droplet-moving system, could optionally
similarly be eliminated if desired, since the electromagnet on its
own could achieve the rotation of such a sphere.
[0298] Equally, the multiple black & white hemispheres
shown--or suchlike spheres, etc., incorporating varied surface
treatments--could be used in respect (each) of a number of
different color filters--say, R, G B--to modulate the quantity of
light of those different colors reaching a display screen, or the
outside world. Equally, the liquid between the substrates could be
an electrolyte, and the orientation of the sphere changed by
applying different charges to said electrolyte.
[0299] As yet another example of the almost innumerable different
applications of the above magnetic+droplet-moving technique, the
magnetic item(s) shown in the lower substrate--or the substrate
bearing them--could be moved sideways, thereby changing the
magnetised sphere's orientation and displayed color or optical
performance, with, optionally, the droplets being used, for
example, to retain the spheres in their current location.
[0300] Whilst only one optical element--in the above two drawings,
a sphere and lens, respectively--are shown within each droplet in
the above diagram, the same principles can be used for multiple
spheres or other optical instruments contained within each single
droplet.
[0301] Equally, the magnetic elements shown in the lower substrate
could be located at any suitable location in the cell, provided
that the magnetised optical instrument may fall within the magnetic
field of said elements at some point in its possible range of
movement.
[0302] It should be noted that the droplet+sphere shown at the left
does not change position or orientation in the above drawing: it is
shown merely to illustrate that the above system could be used in a
display array. Also, the physical size specifications shown in the
drawing are purely to give a sense of one scale that this system
might be operated on: it should not be taken as indicating any
preferred scale or size for this approach.
Droplet Shape-Manipulation to Retain the Position or Orientation of
Optical Instruments within the Droplet
[0303] Also noteworthy is the fact that where droplets contain or
incorporate on their surface solid optical elements which are
caused to change their orientation, or position, as a result of any
controllable forces exerted on them (e.g., magnetic or electric
fields, or electro hydrodynamic forces), the shape or position of
those droplets can be manipulated by electro hydrodynamic or other
suitable forces or position so as to act to restrain said optical
elements from movement where it is desired that they continue to
perform their current optical or other function--i.e., that they do
not change their current position or orientation.
[0304] As a simple example of this very useful technique, and
referring to the drawing above, the electro hydrodynamic,
electrostatic, or electrowetting forces acting on the droplet can
be modulated to cause the droplet's shape to be compressed
vertically--by, for example, making the surface beneath it to
become more hydrophobic--thereby pressing the optical instrument
within the droplet against the substrate beneath, and thereby
exerting (e.g.) frictional forces on it to prevent to changing its
location, or orientation.
[0305] FIG. 28 illustrates this idea. No electrodes or other
orientation/displacement instruments are shown in the drawing, as
we are only concerned here with establishing a possible means of
retaining the sphere's orientation once we have rotated it to the
desired orientation--so the means of achieving the rotation is not
important here.
[0306] It should be appreciated that this approach may be used for
any systems described herein where an optical element is located
within a droplet. The citing of the ability to exert frictional
force on said element is merely an example of how this approach can
be exploited: clearly, many other possible forces can be used to
achieve the same end (i.e., of restraining the optical element's
movement), where the droplet moves said optical element into a
situation where its tendency to change its position or orientation
is less as a result of said droplet movement, than it would have
been without said droplet movement.
[0307] Physical contact between the optical element and another
item is not necessarily required: the droplet may, for example,
move said optical element into an energy field where the forces
acting to retaining the element's current optical performance are
stronger--e.g., it may be moved closer to one or more magnets.
Equally, rather than moving the optical element into a location in
order to achieve such a purpose, the droplet may `drag` it away
from the forces which caused the element to achieve a certain
`optical posture`, so that said posture is retained (or indeed
changed).
[0308] Clearly, where magnetised optical elements are employed,
provisions must be made to ensure the physical distancing of one
from another, lest they are sufficiently magnetically attracted to
each other that they join together. This may be achieved by many
possible alternative means, including physical separation of the
different `cells` of the system, or patterns of wettability to
ensure no droplet, or optical item, is allowed to become
unacceptably close to its neighbours (options, which, of course,
always apply to any droplet system).
[0309] It should also be noted that where one liquid is located
within an electrolyte liquid, or where the droplet is itself an
electrolyte, if one or more electrodes are located in contact with
either said electrolyte liquid, then a charge introduced to said
electrolyte, combined with an appropriate, and oppositely-poled
charge to one or more suitably-located electrodes proximate to the
droplet, and insulated from it, this can provide another
alternative means of changing the shape of the droplet.
Other Droplet/`Optical Instrument within Droplet` `Locking`
Systems
[0310] There are a great many different possible means of enhancing
a droplet's mechanical `resistance` to being displaced from a
position, or a shape or profile, to which it has been moved by
electrical means described herein. In addition, many of these
approaches can also potentially be applied to increasing the forces
retaining the orientation, and/or the position, of optical items
contained within droplets.
[0311] Included within such approaches are the use of materials
such as Bingham's plastic, visco-elastic materials,
electro-rheological fluids and materials within the material from
which droplets are composed, and/or within the material of which
substrates within droplet-using display systems are composed,
where, particularly, the droplet could come into direct contact
with such substrates, or areas of such substrates composed of, or
treated with, such materials.
[0312] Clearly, the primary application/purpose using any of these
materials would be to be able to controllably (e.g., by the
application of a suitable electric field, or electric charge, as
applicable) affect the amount of force necessary to displace a
droplet from a position to which it has been moved by the control
electronics, and/or to retain the droplet's shape, and/or to
inhibit movement of one or more optical elements within the droplet
until such time as the electronic control system wished to change
the applied electric field, or direct electrical charge applied to
the material, so as to `release` the droplet and/or optical
instrument within it from that inhibiting influence--i.e.,
preparatory to changing its position or shape. Thus, for example,
the shear properties, of the droplet's interface with a substrate
with which it is in contact could be changed by the application of
a suitable electric field, or electrical charge.
The Use of AC Voltages in Droplet-Using Display or Light Projection
Systems
[0313] For the avoidance of doubt, some of the effects in this and
my previous patent application documents that involve positioning
of droplets (and indeed some other droplet-manipulating effects)
using electrowetting effect are more controllable when AC voltages
are applied.
[0314] The AC need not be sinusoidal--it can be square pulses, for
example, which are easier to produce with digital electronics.
[0315] Thus, the use of AC, or alternatively DC, voltage for any
appropriate types of my proposed droplet-moving or manipulating
systems are included within the scope of this patent
application.
Electro Hydrodynamic Rotation of a Sphere or Other Optical
Instrument Bearing a Pattern of Differential Surface Tension
[0316] An optical element such as a lens, reflector, prism,
light-blocking element, etc. may be manufactured or treated so as
to incorporate on its outer surface more than one zone of different
surface tension. This approach may be used, in combination with the
various electrical means of changing surface tension discussed
herein, to manipulate the position, or orientation, of such any of
the aforesaid optical elements, in accordance with the principles
and approaches described herein.
Stylus-Employing Versions of Any of the Display Systems Described
Herein, or in my Previous Patent Applications
[0317] In my U.S. Pat. No. 6,924,792, I gave an example of how a
stylus connected to a droplet-based display system may be used. I
should emphasise that my claims with regard to this, and my
existing US electrowetting patent, also include any practical means
of employing a stylus to work in combination with any of the
droplet-based display systems discussed or implied herein. In many
cases such combination will involve the use of the stylus tip to
substitute for some other part of the system described
herein--e.g., delivering an electrical charge to the stylus tip so
that it can be one of the elements generating an electrical field
affecting the droplets, or items within or associated with
them.
Use of Any Droplet System to Control the Brightness of Light
[0318] In this document, and in my preceding patent applications
concerning droplet display and light projection systems, I have
focussed most of my attention on means of controlling the color of
light emerging from droplet-using systems.
[0319] It should be emphasised therefore, for the avoidance of
doubt, that many of my proposed droplet-using display and/or
projection systems may be used to control the brightness of light
emerging from said systems--whether color-selectively, or simply
the brightness of light irrespective of color.
The Use of Droplet Systems for Decorative Effects
[0320] There are many product missions where my proposed
droplet-using display and light-projection systems may be used
simply for decorative effect. As a simple example, the droplets may
be used in such applications as sunglasses or glasses frames, where
the purpose is merely to show a changing display of one or more
different colors on the frames. This type of effect, which may
optionally be constantly-changing, and may present a uniform color,
or many different colors, across a surface to the view of the
observer, can clearly be used in innumerable possible product
applications. I claim all such applications as my invention.
Droplet Systems Used Simply to Redirect Light
[0321] It will be appreciated that whereas many of the droplet
systems discussed by me have been used to change the color of
light, any appropriate members of the systems proposed by me could
be used to switch light reflection or transmission of and on, or to
modulate the direction in which light emerges from said
systems.
[0322] The said systems may simply be used to `bend` light
paths--for example, if an array of droplets--which may comprise
multiple layers of droplet arrays--is used in front of a halogen
light not to change its color, but to direct light which would
otherwise have been emitted `in front` of the lamp to be refracted
so that the user of the system can redirect it to another angle--as
an alternative to physically moving the lamp housing for
example.
[0323] It should be noted that I also claim any means of achieving
the same light-redirection function from a system of lenses in
front of a lamp, where physical manipulation of the lenses, or lens
arrays, allows the user to redirect the light from, say, shining
onto the top of someone's head to shining on to a bowl of flowers a
foot or so away from that person's head. This could, for example,
be achieved by rotating a ring associated with the lens array(s) so
that one or more lens array is moved to one side--thus `bending`
the light accordingly.
Notes
[0324] Use of more than 2 electrodes to position a droplet--i.e.,
by combining the forces of multiple electrodes on `the same side`
to distort, or spread, a droplet.
[0325] It should be emphasised that any systems, or approaches,
involving the use of liquid droplets for display or light-filtering
means described in this document, and in my previous applications,
can be combined in any practical way whatsoever.
[0326] It should also be emphasized that the systems described only
represent a small proportion of the many different ways that the
principles involved can be applied. This, and my previous patent
applications relating to droplets, should be seen in this context,
and my claims are in no way limited to the actual systems
described.
* * * * *