U.S. patent application number 16/899062 was filed with the patent office on 2021-12-16 for anti-glare, privacy screen for windows or electronic device displays.
The applicant listed for this patent is LUMINIT LLC. Invention is credited to RIBERET ALMEIDA, ANTHONY ANG, CASEY SCOTT IRVIN.
Application Number | 20210389505 16/899062 |
Document ID | / |
Family ID | 1000004904129 |
Filed Date | 2021-12-16 |
United States Patent
Application |
20210389505 |
Kind Code |
A1 |
ANG; ANTHONY ; et
al. |
December 16, 2021 |
ANTI-GLARE, PRIVACY SCREEN FOR WINDOWS OR ELECTRONIC DEVICE
DISPLAYS
Abstract
An array of microstructures or frustums on a substrate for
reducing glare for electronic device displays or windows. The
microstructures are designed to nearly perfectly align with the
pixels on the display to avoid adverse viewing effects, such as
Moire effects. Substantially all light from the environment
illuminating the front side of the film containing the
microstructures from all angles is not reflected to the primary
viewer (often viewing at an angle normal to the film). Light
illuminating the microstructure from the environment will reflect
off the microstructures at angles greater than a defined threshold
outside the primary viewers field of view. Thus, glare to the
primary viewer is minimized while glare to other views who view
from other angles than the primary viewer is increased. This
increased glare for other viewers adds privacy for the viewing by
the primary viewer.
Inventors: |
ANG; ANTHONY; (TORRANCE,
CA) ; IRVIN; CASEY SCOTT; (TORRANCE, CA) ;
ALMEIDA; RIBERET; (TORRANCE, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LUMINIT LLC |
Torrance |
CA |
US |
|
|
Family ID: |
1000004904129 |
Appl. No.: |
16/899062 |
Filed: |
June 11, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 1/1609 20130101;
G02B 1/118 20130101 |
International
Class: |
G02B 1/118 20060101
G02B001/118; G06F 1/16 20060101 G06F001/16 |
Claims
1. A privacy screen for a display or a window comprising an array
of frustums positioned on a substrate wherein an index of
refraction of the substrate is comparable to an index of refraction
of the frustum, wherein an index of refraction of the spaces
between the frustums is lower than the index of refraction of the
frustums, and wherein incoming light is controlled in at least one
direction.
2. The privacy screen of claim 1 wherein a base of the frustum is
larger than the top of the frustum.
3. The privacy screen of claim 1 wherein the substrate and the
frustums comprise the same material or different materials.
4. The privacy screen of claim 1 wherein the frustums are nearly
perfectly aligned with pixels of a display.
5. The privacy screen of claim 1 comprising an anti-reflective
coating, a transparent dielectric coating, or a combination
thereof.
6. The privacy screen of claim 1 wherein the substrate is flexible,
rigid, or a combination thereof.
7. The privacy screen of claim 1 wherein the frustums comprise
conical frustums, square frustums, pentagonal frustums, hexagonal
frustums, octagonal frustums, n-gon frustums, rectangular frustums,
diamond frustums, rhombus frustums, quadrilateral frustums, star
frustums, donut frustums, irregular polygon frustums, frustums
hollowed out by removing a central region of the frustum of a
certain shape, or any combination thereof.
8. The privacy screen of claim 1 wherein the height of the frustum
is like the width of the frustum.
9. The privacy screen of claim 1 wherein one or more parameters of
the frustums are varied to optimize optical performance, wherein
the parameters include height, size, spacing from a center of one
frustum to a center of an adjacent frustum, arrangement, rotation
of the frustum about an axis normal to a surface of the substrate,
angles between a side of the frustum and the base of the frustum,
centeredness of the top surface of the frustums with respect to the
base of the frustums, index of refraction of the frustums, and
combinations thereof.
10. The privacy screen of claim 1 wherein a portion of the top
surface of the frustum is raised up above the rest of the surface
of the frustum or wherein the portion of the top surface of the
frustum is raised up is a lip around the perimeter of the top
surface of the frustum or a region within the top surface of the
frustum, or a mixture thereof.
11. The privacy screen of claim 1 wherein the top surfaces of the
frustums are co-planar with each other and parallel to the surface
of the substrate or wherein the top surfaces of the frustums are
parallel to each other but not parallel to the surface of the
substrate or wherein a tilt of the top surfaces of the frustums
vary by a gradient with respect to the surface of the
substrate.
12. The privacy screen of claim 1 wherein the frustums comprise
steep side walls having a steepness of about 80 degrees from a
plane of the surface of the substrate, wherein light illuminating
the substrate does not produce significant reflective glare into a
primary viewing angle range of about +/-30 degrees with respect to
normal to the surface of the substrate, but does produce glare
outside of the primary viewing angle range.
13. The privacy screen of claim 1 wherein an internal angle of a
side of the frustum to the base of the frustum is in the range of
about 45 to 90 degrees.
14. The privacy screen of claim 1 wherein gaps or no gaps exist
between the bases of adjacent frustums in the array.
15. The privacy screen of claim 14 wherein the gap between the
bases of adjacent frustums comprises a size of about 0-5 times the
width of the base of the frustums.
16. The privacy screen of claim 1 wherein the frustums are an
inverse surface relief of frustums or a mixture of frustums and
inverse surface relief of frustums and wherein the inverse surface
relief structures have a lower index of refraction than surrounding
material.
17. The privacy screen of claim 1 wherein a second substrate is
bonded to the top surfaces of the frustums, wherein the top
surfaces of the frustums are in contact with a surface of the
second substrate, wherein the second substrate comprises a same
index of refraction as the frustums and a first substrate that
comprises the frustums, wherein there is no significant
back-scattering of light passing through an interface between the
top surfaces of the frustums and the surface of the second
substrate, and wherein there is no significant degradation in
transmission of light passing through the first substrate, the
frustums, and second substrate due to the interfaces.
18. The privacy screen of claim 1 wherein a second substrate is in
contact with a portion of the top surfaces of each frustum, and
wherein the second substrate comprises a same index of refraction
as the frustums and the first substrate.
19. The privacy screen of claim 1 wherein the frustums are
rectangular frustums that extend over the entire privacy screen or
beyond the edges of the privacy screen.
20. A method of fabricating a substrate comprising an array of
microstructures or nanostructures on one side of the substrate
comprising a photolithography process or a mechanical process;
which includes applying a rastering laser beam to develop and form
a series of identical or non-identical microstructures or
nanostructures wherein the microstructures or nanostructures
comprise frustums or inverse frustums, and wherein the developed
photoresist can be used to make molds, replicas, final parts, or
mixtures thereof.
Description
TECHNICAL FIELD
[0001] This application is directed to an anti-glare, privacy
screen for windows or electronic device displays. In particular,
this screen is designed so as to selectively reduce environmental
glare relative to the primary viewer, while increasing glare for
others outside of the primary viewer's field of view. This privacy
screen thus improves the quality of the view for the primary viewer
and hinders unwanted viewing by nearby bystanders.
BACKGROUND
[0002] Older television screens used grey tinting on the screen to
help combat ambient light that interfered with enjoyment of the
picture. However, glare could still come from a light source
reflecting from the smooth surface of the television glass. One way
to combat this glare was to arrange the television and lighting to
reduce the glare on the television screen. Another way for more
expensive television screens was to include a diffuser surface to
combat the direct reflections of light. However, these implements
failed to remedy the instance of lights behind the user causing
some haze on the screen.
[0003] For hand-held electronic devices, in addition to glare, a
lack of privacy is a major concern, especially in crowded areas.
Although dark-colored, tempered glass and plastic films are
commercially available and can be used, these measures merely
reduce glare at all angles, so little to no privacy protection is
provided. Moreover, these types of screen protectors adversely
affect the screen brightness and clarity. Also, in hand-held
devices, increasing the screen brightness of the device to
compensate for a dimmer screen can drain the battery quickly. Other
measures, such as micro-louver screen protectors, can suffer from
decreased light transmittance, reduced screen clarity, diminished
color contrast, image distortion, and glare from light behind the
user.
[0004] Thus, there exists a need for an effective solution to the
problem of lack of privacy for the screens of electronic devices
while at the same time decreasing glare for the primary viewer and
increasing glare for others, which the present disclosure
addresses.
BRIEF SUMMARY
[0005] The present disclosure is directed to a privacy screen for
an electronic display or a window comprising an array of frustums
positioned on a substrate wherein the index of refraction of the
substrate is comparable to the index of refraction of the frustum,
wherein the index of refraction of the spaces between the frustums
is lower than the index of refraction of the frustums, and wherein
incoming light is controlled in at least one direction.
[0006] In one embodiment, the substrate and the frustums comprise
the same material.
[0007] In another embodiment, the width of the top of the frustums
is about 8-16 microns wide and the width of the base is about 10-20
microns wide.
[0008] In another embodiment, the base of the frustum is larger
than the top of the frustum.
[0009] In another embodiment, the frustums are perfectly aligned
with pixels of the device display.
[0010] In another embodiment, the substrate is flexible, rigid, or
a combination thereof.
[0011] In another embodiment, the frustums comprise conical
frustums, square frustums, pentagonal frustums, hexagonal frustums,
octagonal frustums, n-gon frustums, irregular polygon frustums,
star frustums, donut frustums, frustums hollowed out by removing a
central region of the frustum of a certain shape, or any
combination thereof.
[0012] In another embodiment, one or more of parameters of the
frustums are varied to optimize optical performance, wherein the
parameters include height, size, spacing from a center of one
frustum to a center of an adjacent frustum, arrangement, rotation
of the frustum about an axis normal to a surface of the substrate,
angles between a side of the frustum and the base of the frustum,
centeredness of the top surface of the frustums with respect to the
base of the frustums, index of refraction of the frustums, and
combinations thereof.
[0013] In another embodiment, the geometric shape of each frustum
results from a subtraction of a smaller frustum from a larger
frustum, wherein the larger frustum and the smaller frustum share
the same top surface, wherein the top surface is parallel to a
plane of a surface of the substrate.
[0014] In another embodiment, the top surfaces of the frustums are
parallel to each other and either parallel to a plane of a surface
of the substrate or not parallel to the surface of the
substrate.
[0015] In another embodiment, the frustums with tops that are
parallel to the surface of the substrate comprise steep side walls
having a steepness of about 80 degrees from a plane of the surface
of the substrate, wherein light illuminating the substrate does not
produce reflective glare into a primary viewing angle range of
about +/-30 degrees with respect to normal to the surface of the
substrate, but does produce glare outside of the primary viewing
angle.
[0016] In another embodiment, an internal angle of a side of the
frustum to the base of the frustum is greater than or equal to 45
degrees.
[0017] In another embodiment, gaps or no gaps exist between the
bases of adjacent frustums in the array.
[0018] In another embodiment, the gap between the bases of adjacent
frustums comprises a size of about 0-5 times the base of the
frustums.
[0019] In another embodiment, each frustum is initially positioned
randomly on the surface of the substrate without overlapping an
adjacent frustum, wherein additional different frustums of various
sizes are iteratively placed in-between existing frustums, wherein
initial spaces between the frustums are filled up with the
additional different frustums of various sizes, and wherein all
frustums are fully intact.
[0020] In another embodiment, each frustum is initially positioned
randomly on the substrate without overlapping an adjacent frustum,
wherein additional different frustums of various sizes are
iteratively placed in-between existing frustums, wherein initial
spaces between the frustums are filled up with the additional
different frustums of various sizes except for a predetermined
border, wherein no frustums overlap each other, and wherein all
frustums are fully intact. This predetermined border provides a gap
between frustums.
[0021] In another embodiment, the microstructures or nanostructures
on the surface of the substrate are an inverse surface relief of
frustums or a mixture of frustums and inverse surface relief of
frustums and wherein the inverse surface relief structures have a
lower index of refraction than the surrounding material. In another
embodiment, the microstructures or nanostructures on the substrate
are a combination of frustums and inverse frustums.
[0022] In another embodiment, a second substrate is bonded to the
top surfaces of the frustums, wherein the top surfaces of the
frustums is in contact with a surface of the second substrate,
wherein the second substrate comprises a same index of refraction
as the frustums and a first substrate, wherein there is no
significant back-scattering of light passing through an interface
between the top surfaces of the frustums and the surface of the
second substrate, and wherein there is no significant degradation
in transmission of light passing through the first substrate, the
frustums, and second substrate due to the interfaces.
[0023] In another embodiment, the privacy screen includes an
anti-reflective coating, a transparent dielectric coating, or a
combination thereof.
[0024] Also disclosed herein is a method of fabricating a flexible
or rigid substrate including an array of microstructures or
nanostructures on one side of the substrate comprising coating a
substrate with a uniform thickness of photoresist polymer; which
includes applying a rastering laser beam to form the microstructure
or nanostructure to make molds, replicas, final parts, or mixtures
thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1: Square Frustum.
[0026] FIG. 2: Conical Frustum.
[0027] FIG. 3: Pentagonal Frustum.
[0028] FIG. 4: Top View of Array of Square Frustums.
[0029] FIG. 5: Example of Array of Square Frustums.
[0030] FIG. 6: Array of Rectangular Frustums.
[0031] FIG. 7: Array of Rectangular Frustums with lengths
significantly longer than widths.
[0032] FIG. 8: Side view of Frustum with lip on surface extending
around perimeter.
[0033] FIG. 9: Dimensional view of Frustum with lip on surface
extending around perimeter.
[0034] FIG. 10: Side View of Grid Array of Square Frustums with no
gap between Frustums.
[0035] FIG. 11: Top View of Array of Square Frustum with gaps in
between Frustums.
[0036] FIG. 12: Side View of Grid Array of Square Frustums with gap
between Frustums.
[0037] FIG. 13: Array of Rectangular Frustums with lengths
significantly longer than widths and gaps.
[0038] FIG. 14: Top View of Array of Hexagonal Frustums.
[0039] FIG. 15: Array of Square Frustum of two Different Sizes and
a Certain Checkerboard Pattern.
[0040] FIG. 16: Array of Square Frustum of two Different Sizes and
a Certain Pattern.
[0041] FIG. 17: Depiction of Rectangular Frustums.
[0042] FIG. 18: Representing Rectangular Frustums following paths
of concentric circles.
[0043] FIG. 19: Representing Rectangular Frustums following paths
of concentric squares.
[0044] FIG. 20: Representing Rectangular Frustums following paths
of triangle waves.
[0045] FIG. 21: Representing Rectangular Frustums following paths
of curved waves.
[0046] FIG. 22: Side View of Film consisting of an array of Square
Frustum on the Back Surface of a Substrate.
[0047] FIG. 23: ANGLE OF INCIDENCE zero degrees.
[0048] FIG. 24: ANGLE OF INCIDENCE 5 degrees.
[0049] FIG. 25: ANGLE OF INCIDENCE 10 degrees.
[0050] FIG. 26: ANGLE OF INCIDENCE 15 degrees.
[0051] FIG. 27: ANGLE OF INCIDENCE 20 degrees.
[0052] FIG. 28: ANGLE OF INCIDENCE 25 degrees.
[0053] FIG. 29: ANGLE OF INCIDENCE 30 degrees.
[0054] FIG. 30: ANGLE OF INCIDENCE 40 degrees.
[0055] FIG. 31: ANGLE OF INCIDENCE 50 degrees.
[0056] FIG. 32: ANGLE OF INCIDENCE 60 degrees.
[0057] FIG. 33: ANGLE OF INCIDENCE 70 degrees.
[0058] FIG. 34: Side View of Film with Array of Frustums showing a
Primary Viewing Angle which is Normal to the First Surface of the
Film (not drawn to scale).
[0059] FIG. 35: Side View of Film with Array of Frustums showing a
Primary Viewing Angle which is not Normal to the First Surface of
the Film (not drawn to scale).
[0060] FIG. 36: Side View of Field of Interfaces between two
Indexes of Refraction (n1 and n2).
[0061] FIG. 37: Side View of Field of Interfaces between two
Indexes of Refraction (n1 and n2).
[0062] FIG. 38: Side View of Field of Interfaces between two
Indexes of Refraction (n1 and n2).
[0063] FIG. 39: Isometric View of Field of Flat Interfaces between
two different Indexes of Refraction (n1 and n2) with n2 above each
interface and n1 below each interface.
[0064] FIG. 40: Side View of Interfaces between two Indexes of
Refraction (n1 and n2) arranged in a configuration.
[0065] FIG. 41: Side View of array of Square Frustums on Substrate
with Index of Refraction n1 in Frustums and base substrate and
Index of Refraction n2 in space above Frustums.
[0066] FIG. 42: Side View of Configuration of a Field of Interfaces
between two Different Indexes of Refraction, n1 and n2.
[0067] FIG. 43: Side View of array of Square Frustums on Substrate
with Index of Refraction n1 in Frustums and Bottom Substrate and
Index of Refraction n2 in space above Frustums and Below Second
Substrate on top of Frustums.
[0068] FIG. 44: Side View of Substrate with Embedded regions with a
different index of refraction than the substrate.
[0069] FIG. 45: Side View of Substrate with Embedded regions with a
different index of refraction than the substrate.
[0070] FIG. 46: Side View of Film consisting of an array of Square
Frustum between Two Substrates.
[0071] FIG. 47: Side View of Array of Square Frustums with Second
Substrate bonded to the tops of the Frustums where all materials
have the Substantially the Same Index of Refraction.
[0072] FIG. 48: Ambient Light Source on Film-Lambertian input light
direction with no screen.
[0073] FIG. 49: A ray diagram of a radiant intensity distribution
plot of Ambient Light Source on Film-Lambertian input light
direction with no screen.
[0074] FIG. 50: Radiant intensity distribution plot through
Film.
[0075] FIG. 51: Radiant intensity distribution of a single optical
element.
[0076] FIG. 52: Radiant intensity distribution plot of Light
Reflected off Film.
[0077] FIG. 53: Radiant intensity distribution plot of Light
Reflected off Film for a single optical element.
[0078] FIG. 54: Lambertian Reflector with Collimated Input.
[0079] FIG. 55: Radiant intensity distribution plot of Lambertian
Reflector with Collimated Input.
[0080] FIG. 56: Radiant intensity distribution plot of Light
Reflected from Film and Lambertian Reflector Combined.
[0081] FIG. 57: Light Reflected from Film and Lambertian Reflector
Combined.
[0082] FIG. 58: Method of Making Privacy Screen with Frustums.
[0083] FIG. 59: Method of Making Privacy Screen with Uneven
Frustums.'
[0084] FIG. 60: Side views of three different types of frustum in
which the tops of the frustums are either all parallel to the
surface of the substrate or the tops of the frustums are all
parallel to each other but not parallel to the surface of the
substrate, or the tilt of the top surfaces of modified frustums
vary by a gradient with respect to the surface of the
substrate.
[0085] FIG. 61: Example of top view of square frustum in which
alternating frustums are rotated 90 degrees.
[0086] FIG. 62: Side view of non-right frustums in which the top of
the frustum is not centered above the base of each frustum.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0087] Electronic screens of laptops, tablets, phones, e-readers,
etc. under ambient light conditions must regulate glare from direct
reflected images originating from smooth optical surfaces as well
as haze coming from diffuse reflective surfaces in order to provide
a clear, high contrast image. A vibrant image is vital for reading
to obtain informational content, to protect from distraction, and
to provide a comfortable view of the image. A clear, distinct image
reduces eye strain and other biological problems. In addition,
screen privacy is important when the user is in a public or
semi-public setting.
[0088] The present application relates to a privacy screen having a
solid substrate that is transparent to some or all of the
ultraviolet, visible and infrared light spectrum. The reflected
light from the initial screen surface is scattered to break up the
strong imaging specular reflection, and also to reduce the rays
that scatter in the direction of the intended primary viewer. Most
of the light must be allowed to transmit to the secondary layers,
which house the e-ink, and are close to the surface normal. In this
manner, the reflected light from the e-ink is relatively strong
compared to the scattered light from the first surface when viewed
by the primary user, which establishes a high signal to noise
ratio. The aim is to reduce eye strain and other long-term
biological degradation to the eyes. In addition, a secondary
effect, which is also favorable, is to make the scattered light
from the first surface stronger outside the primary viewing angle.
The signal to noise is therefore inverted towards the unwanted
audience. This provides increased privacy for the primary viewer
when an electronic device is used in public places.
[0089] This privacy screen contains a clear substrate containing
surface microstructures made of optically clear material, which
serve as optical elements that allow light, within a select range
of angles from the normal to the plane of a window or display
screen, to pass through and reach the window or display screen.
Other incident light undergoes total internal reflection (TIR)
within the microstructures before being reflected back to the
viewer. Thus, such a screen reduces environmental glare to the
primary viewer who is viewing the screen within the range of angles
around the primary viewing angle, while increases glare to other
viewers outside the viewer's field of view, which provides privacy
for the viewer and improves the screen view for the primary
viewer.
[0090] More specifically, this application is directed to a privacy
screen having a substrate comprising nanostructures or
microstructures, known as frustums, on a surface of the substrate.
The frustums can cover the entire width and/or length of the
substrate or partially cover the substrate. A frustum is generally
defined as any part of a geometric shape between two parallel
planes. FIG. 1 is a drawing of a square frustum. FIG. 2 is a
drawing of a conical frustum. FIG. 3 is a drawing of a pentagonal
frustum. The frustums are arranged in an array, such as that shown
in FIGS. 4 and 5, which are examples of a top view of an array of
square frustums. In both of those examples, the base of the frustum
is larger than the top surface of the frustum so that the sides of
the frustum are slanted at an angle. FIG. 6 is a drawing of an
array of rectangular frustums. FIG. 7 is a drawing of an array of
rectangular frustums where the lengths are significantly longer
than the widths. The length of the frustum can extend the entire
length of the screen. The rectangular frustums can extend over the
entire privacy screen or beyond the edges of the privacy screen.
This embodiment can have the effect of reducing the glare on one
axis while not reducing the glare in the perpendicular axis.
[0091] In another embodiment, a portion of the top surface of the
frustum is raised up above the rest of the surface of the frustum,
as in a lip of the frustum. A side view of a frustum having a lip
on the surface that extends around the top surface of the frustum,
shown in FIG. 8. FIG. 9 shows a dimensional view of a frustum with
a lip on the top surface, which extends around the perimeter of the
top surface. In general, the lip has a width and a height between
0.1 to 5 microns.
[0092] In some embodiments, the frustum base ranges from about 1 to
500 microns in width and the frustum top surface ranges from about
0.5 to 499 microns in width. Generally, the height of a frustum is
between about 1 to 500 microns. In another embodiment, the frustums
have a height to base aspect ratio of about 1:1, so that the height
is similar to the base of the frustum. For an individual frustum,
the base of the frustum is wider than the top of the frustum.
[0093] The top surfaces of the frustums can be centered or
off-centered above the base of the frustum. FIG. 62 shows the side
view of non-right frustums in which the tops are not centered above
the bases of the frustums. The top surfaces can be off-centered
according to a gradient offset across the array or can be
off-centered according a constant offset. Also, some of the
frustums can be centered and some off-centered in the same or
varying amounts so the slopes of the sides of the frustums are
different. The tops of the frustums can be parallel to each other
and not parallel to the surface of the substrate, as shown in FIG.
60. In addition, the tops of the frustums can be tilted, by a
constant amount, a varying amount, a gradient, or a combination
thereof. Both parameters, being off-centered and tilted, can change
the primary viewing angle of the privacy screen because the
reflection of glare is different with different combinations and
compositions of frustums. In an embodiment, the geometric shape of
each frustum results from a subtraction of a smaller frustum from a
larger frustum, wherein the larger frustum and the smaller frustum
share the same top surface, wherein the top surface is parallel to
a plane of a surface of the substrate.
[0094] FIG. 4 illustrates an array where there are no gaps between
the bases of adjacent frustums. A side view of the square frustum
array with no gaps is shown in FIG. 10. In FIG. 11, which is also
an example of a top view of an array of square frustums, there are
gaps between the bases of adjacent frustums. The gap between the
bases of adjacent frustums comprises a size of about 0-5 times the
width of the base of the frustums. A side view of the square
frustum array with gaps is shown in FIG. 12. FIG. 13 shows a
rectangular array of frustums with lengths that are significantly
longer than the widths of each base and comprising a gap between
the frustums.
[0095] In another embodiment, the frustums are conical frustums,
square frustums, pentagonal frustums, hexagonal frustums, octagonal
frustums, n-gon frustums, rectangular frustums, diamond frustums,
rhombus frustums, quadrilateral frustums, star frustums, donut
frustums, irregular polygon frustums, frustums hollowed out by
removing a central region of the frustum of a certain shape, or any
combination thereof. The frustums can be an inverse surface relief
of frustums or a mixture of frustums and inverse surface relief of
frustums wherein the inverse surface relief structures have a lower
index of refraction than the surrounding material. FIG. 14
illustrates a top view of an array of hexagonal frustums. In some
embodiments, the frustums in the array are all the same shape and
size. However, the frustums can also be of different shapes and/or
different sizes, as shown in FIGS. 15 and 16, which show a top view
of different patterns of frustum arrays. Each frustum is initially
positioned randomly on the surface of the substrate without
overlapping an adjacent frustum, wherein additional different
frustums of various sizes are iteratively placed in-between
existing frustums, wherein initial spaces between the frustums are
filled up with the additional different frustums of various sizes,
and wherein all frustums are fully intact. In another embodiment,
all frustums are fully intact except for a predetermined boarder
around each frustum. The frustums can also be rotated with respect
to each other.
[0096] In another embodiment, the frustums can have a cross section
of a square or rectangular frustum but follow a path of a pattern
in another direction. In this manner, the structures form modified
frustums. For example, the rectangular frustums in FIG. 7 can be
described as frustum with a cross section of a rectangular frustum
and following the paths of parallel lines in the other dimension,
as shown in FIG. 17. Likewise, FIGS. 18-21 show other patterns
which represent paths that frustums can follow. These are top views
of the patterns that the centers of the frustums follow. In these
cases, the cross sections are rectangular frustums, but in other
embodiments, the cross sections can be frustums with other cross
sections. FIG. 17 shows an arrangement of parallel rectangular
frustums as parallel lines indicating the arrangement of the paths
of the center of each frustum on the substrate. FIG. 18 shows a
representation of a top view of rectangular frustums following
paths of concentric circles. FIG. 19 shows a representation of a
top view of rectangular frustums following paths of concentric
squares. FIG. 20 shows a representation of rectangular frustums
following paths of triangle waves. FIG. 21 shows a representation
of a top view of rectangular frustums following paths of curved
waves. The rectangular frustums can extend along the entire length
of the privacy screen, or width of the screen, or can extend beyond
the edges of the screen.
[0097] The substrate has frustums on one surface of the substrate,
where the base of the frustum is attached to the back surface of
the substrate. The substrate and the frustum can be the same or
different material. The substrate can be a polymer, glass, ceramic,
metal, or a combination thereof. In one embodiment, the substrate
is a thermoplastic polymer film, such as polycarbonate or
polyethylene terephthalate. The substrate can be flexible, rigid,
or a combination thereof.
[0098] The substrate is transparent to ultra-violet, visible,
infrared light, or mixtures thereof. The transparency is adjustable
so that the substrate and the frustums are transparent to a very
narrow range of light or to a very broad range of light. In one
embodiment, the index of refraction of the substrate and the
frustums are the same and in another embodiment, the index of
refraction of the substrate and the frustums are similar but not
exactly the same.
[0099] An anti-reflection coating can be placed on the top surface
of the substrate, as shown in FIG. 22, where the substrate is
labelled as "First Substrate." When light from the environment is
incident on the front surface of the substrate, the anti-reflection
coating prevents light from reflecting off the front surface of the
substrate. Thus, the ambient light transmits through the substrate
and reaches the frustums. The anti-reflection coating can cover the
entire surface or part of the surface. The anti-reflection coating
can cover the top surface of the frustum but not the sides of the
frustum. The anti-reflection coating can be one or more dielectric
layers. The substrate can comprise both an anti-reflective coating
and a transparent dielectric coating.
[0100] In one embodiment, the index of refraction of the substrate
and the microstructures are substantially the same, which allowed
most light to transmit from the substrate to the microstructures.
The index of refraction of the space outside the substrate and
between the frustums is significantly different from the index of
refraction of the frustums, which have a higher index of
refraction. The side walls of the frustums are steep enough so as
to cause total internal reflection to occur for the light
transmitted through the substrate at certain angles with respect to
the plane of the substrate, as seen in the tray tracing of FIGS.
23-33.
[0101] FIGS. 23-33 show the side view of a film with an array of
square frustums where the incident light that illuminates the front
side of the substrate has a certain angle of incidence with respect
to the normal surface of the substrate. The ray tracing shows the
path of light in each situation. FIG. 23 shows the angle of
incidence at zero degrees. FIG. 24 shows the angle of incidence at
five degrees. FIG. 25 shows the angle of incidence at ten degrees.
FIG. 26 shows the angle of incidence at fifteen degrees. FIG. 27
shows the angle of incidence at twenty degrees. FIG. 28 shows the
angle of incidence at twenty-five degrees. FIG. 29 shows the angle
of incidence at thirty degrees. FIG. 30 shows the angle of
incidence at forty degrees. FIG. 31 shows the angle of incidence at
fifty degrees. FIG. 32 shows the angle of incidence at sixty
degrees. FIG. 33 shows the angle of incidence at seventy
degrees.
[0102] To further elaborate, a frustum having a steep wall has an
angle between the base of the frustum and the side wall, which is
greater than a certain threshold angle. In another embodiment, the
frustums with tops that are parallel to the surface of the
substrate comprise steep side walls having a steepness of about 80
degrees from a plane of the surface of the substrate, wherein light
illuminating the substrate does not produce reflective glare into a
primary viewing angle range of about +/-30 degrees with respect to
normal to the surface of the substrate, but does produce glare
outside of the primary viewing angle. An internal angle of a side
of the frustum to the base of the frustum is in the range of about
45 to 90 degrees. This structure results in a percentage of light
that experiences total internal reflection on the side walls of the
frustums and is transmitted fully through the film, and another
percentage that experiences multiple total internal reflection
events on surfaces of the frustums and/or a second substrate to
which the tops of the frustums might be bonded wherein the light is
ultimately reflected to the front surface of the first substrate.
The reflected light is then transmitted through the first surface
and at an angle with respect to normal to the film and is outside
of the viewing angle of the primary viewer. The primary viewing
angle is the angle from which the primary viewer observes the
substrate. The substrate minimizes the glare for the primary viewer
by minimizing the glare in an angular viewing range around the
primary viewing angle. At the same time, glare is still present at
angles outside of the angular viewing range of the primary viewing
angle. The glare increases the difficulty of outside viewers to see
the substrate and anything on the other side of the substrate, such
as words and images.
[0103] FIG. 34 shows a two-dimensional side view of a primary
viewing angle of the substrate and the range of angles around the
primary viewing angle in which the glare is minimized. The range of
angles around the primary viewing angle in are within the plane of
the figure. A three-dimensional frustum can have a
three-dimensional range of angles around the primary viewing angle
in which the glare is reduced. This is accomplished by having side
walls of a frustum, which are perpendicular to multiple axes in a
three-dimensional space. Examples include square frustum, hexagonal
frustum, rectangular frustum and octagonal frustum. In this way, a
privacy screen consisting of multiple frustums can create a
three-dimensional cone of a range of angles around a primary
viewing angle in which the glare is minimized. The shape of this
cone can be adjusted by varying the number of side walls of the
frustums and the three-dimensional positioning of the side walls of
the frustums. The three-dimensional range of angles in which glare
is reduced can be within an irregular cone. Two-dimensional
figures, such as FIG. 34 can be used to represent how ranges of
angles of minimized glare or maximized glare are created in a
three-dimensional space. There is a range of angles that are
outside the primary viewing angle range where reflection of glaring
light is present. Because the reflection of glaring light is
present in this range of angles outside the viewing angle range, it
is difficult to see the privacy screen or to see anything on the
other side of the privacy screen. Therefore, the reflected glaring
light, which is present outside the primary viewing angle range,
adds to the privacy for the primary viewer in viewing through the
privacy screen. FIG. 35 shows a side view of a substrate with an
array of frustums showing a primary viewing angle, which is not
normal to the first surface of the substrate. Here for the primary
viewing angle, which is a range of angles is like a cone shape, the
reflection of glaring light is minimized. Glare is present in a
range of angles that are outside the primary viewing angle. The
range of angles is different on either side of the primary viewing
angle.
[0104] FIGS. 36-40 illustrate the idea of interfaces of regions of
two different indexes of refraction that can be arranged in various
ways. FIG. 36 illustrates a side view of a field of interfaces
between two indexes of refraction (n1 and n2). FIG. 37 illustrates
a side view of a field of interfaces between two indexes of
refraction (n1 and n2). FIG. 38 illustrates a side view of a field
of interfaces between two indexes of refraction (n1 and n2). FIG.
39 illustrates an isometric view of a field of flat interfaces
between two indexes of refraction (n1 and n2) with n2 above each
interface and n1 below each interface. FIG. 40 is a side view of
interfaces between two indexes of refraction (n1 and n2) arranged
in a configuration. FIG. 40 shows how these interfaces between two
different indexes of refraction can be designed to have the same
pattern and effect as the square frustums arranged as an array on
the back side of a substrate. FIG. 41 is a side view of an array of
square frustums on a substrate with index of refraction n1 in
frustums and substrate and index of refraction n2 in the space
above the frustums.
[0105] In another embodiment, the total internal reflection on the
back side of the first substrate is accomplished by embedding
regions of lower index of refraction within the first substrate,
shown in FIG. 42. FIG. 42 is a side view of a configuration of a
field of interfaces between two different indexes of refraction, n1
and n2. FIG. 43 is a side view of an array of square frustums on a
substrate with index of refraction n1 in frustums and substrate and
index of refraction n2 in the space above the frustums and below
the second substrate on top of the frustums. By comparing FIGS. 43
and 42, it is shown that the two different methods can be used to
create a substrate with the same geometry and function. The regions
of lower index of refraction can be created by embedding a solid,
liquid, or gas with a lower index of refraction that the index of
refraction of the substrate, or by creating regions of a vacuum.
The regions of lower index of refraction have the opposite polarity
of the shapes of the frustums.
[0106] In another embodiment, regions of various shape and
arrangement consisting of vacuum or materials with an index of
refraction lower than the surrounding substrate can be embedded in
the substrate. Two examples of this are shown in FIGS. 44 and 45.
FIG. 44 shows a side view of a substrate with index of refraction
n1 with embedded regions with a different index of refraction n2
than the substrate. FIG. 45 shows a side view of a substrate with
index of refraction n1 with embedded regions with a different index
of refraction n2 than the substrate.
[0107] One or more of parameters of the frustums can be varied to
optimize optical performance, wherein the parameters include
height, size, spacing from a center of one frustum to a center of
an adjacent frustum, arrangement, rotation of the frustum about an
axis normal to a surface of the substrate, angles between a side of
the frustum and the base of the frustum, centeredness of the top
surface of the frustums with respect to the base of the frustums,
index of refraction of the frustums, and combinations thereof. FIG.
60 shows side views of three different types of frustum in which
the tops of the frustums are either all parallel to the surface of
the substrate or the tops of the frustums are all parallel to each
other but not parallel to the surface of the substrate, or the tilt
of the top surfaces of modified frustums vary by a gradient with
respect to the surface of the substrate.
[0108] In one embodiment, there is an array of square frustum in
which alternating frustum are rotated 90 degrees with respect to
each other, as seen in FIG. 61. In this embodiment, each row of
alternating frustum is combined with other rows of alternating
frustum such that the frustum in each column are also alternating
in their rotation by 90 degrees. In alternative embodiments, the
rotation of the alternating frustums can be any angle between 0 to
360 degrees and the frustums can be other shapes besides squares,
such hexagons or triangles or octagons or other shapes.
Additionally, there can be a series of frustums in which each
frustum in the series is successively rotated a fixed amount,
between 0 and 360 degrees, and then the series repeats as a
pattern. For example, the first square frustum in a series could be
rotated 0 degrees, the second rotated 15 degrees, the third rotated
another 15 degrees to make a total rotation of 30 degrees, the
fourth square frustum in the series rotated a total of 45 degrees,
the fifth square frustum in the series rotated 60 degrees, the
sixth frustum in the series rotated 75 degrees. Next, the series
would repeat over and over across the entire film. Multiple rows of
these repeating series would be combined in this embodiment.
Arranging the slanted sides of the frustums to face multiple
directions increases the directions along which glare is decreased
for the primary viewer and increased for viewers outside the range
of the primary viewing angle. The slanted sides of the frustum can
be arranged to face multiple directions by rotating the frustum in
a pattern, as described above, or randomly.
[0109] In another embodiment, the privacy screen has two
substrates, with the frustums in between them, as shown in FIGS. 46
and 47. The index of refraction of the first substrate, frustums,
and second substrate are all substantially the same, as seen in
FIG. 41. As a result of the matching indexes of refraction, the
light that is transmitted through the frustums is also transmitted
through the second substrate. FIG. 46 shows a side view of a
privacy screen or film with an array of square frustums in between
two substrates with an antireflection coating on the front surface
of the first substrate. FIG. 47 shows a side view of an array of
square frustums with a second substrate bonded to the tops of the
frustums. In this embodiment, the tops of the frustums are in full
contact with the surface of the second substrate for all the area
of the tops of the frustum.
[0110] In the embodiment of two substrates, the substrates can be
the same or different composition. Also, the two substrates can
have the same or different index of refraction. In one embodiment,
a second substrate is bonded to the top surfaces of the frustums,
wherein the top surfaces of the frustums is in contact with a
surface of the second substrate, wherein the second substrate
comprises a same index of refraction as the frustums and a first
substrate, wherein there is no significant back-scattering of light
passing through an interface between the top surfaces of the
frustums and the surface of the second substrate, and wherein there
is no significant degradation in transmission of light passing
through the first substrate, the frustums, and second substrate due
to the interfaces. The tops of the frustums that will be adjacent
to or bonded to that second substrate do not have an
anti-reflective coating.
[0111] In another embodiment, a small gap remains between most of
the tops of the frustums and the second substrate. The gap can be
formed by the tops of the frustums not being flat but rather having
a portion of the top of the frustums which is raised up above the
rest of the top surface. FIG. 8 shows the side view of a frustum
with a lip on surface of the top of the frustum which extends
around perimeter. The second substrate would be in full contact
with the tops of the lips, which are the portions of the tops of
the frustums, which are raised up above the rest of the tops of the
frustums. However, there would be a gap between the tops of the
frustums where there is no lip and the surface of the second
substrate. This gap can be filled with air or a vacuum or other
material, which has a lower index of refraction than the frustums
and which is comparable in index of refraction to the index of
refraction in the space in between the frustums. In general, the
lip has a width and a height between 0.1 to 5 microns.
Alternatively, in another embodiment, the top of each frustum would
have the center of the top of the frustum raised up above the rest
of the top of the frustum, rather than the perimeter of the top of
the frustum being raised up above the rest of the top of the
frustum. It would be the raised center of each frustum, which would
contact the second substrate. When a second substrate is put in
contact with the tops of the frustums from the first substrate,
then a small air gap remains between most of the tops of the
frustums and the second substrate, which can improve performance.
Alternatively, another part of the top of each frustum could be
raised up, rather than the center or the perimeter.
[0112] FIGS. 48-53 show the light incident on the substrate, the
light transmitted through the substrate, and the light reflected
off the substrate. FIG. 48 shows a graph of an ambient light source
on a film substrate with Lambertian input light direction with no
screen. FIG. 49 is a ray diagram with a limited number of rays
representing a radiant intensity distribution plot of an ambient
light source on a film substrate with Lambertian input light
direction with no screen. FIG. 50 shows a radiant intensity
distribution plot of the result of a Lambertian input on the
privacy screen and profile of the light that transmits through the
film. FIG. 51 shows a radiant intensity distribution plot of a
single optical element for a privacy screen that has a substrate,
an array of square frustums, and a second substrate on top of the
frustums. FIG. 52 shows a radiant intensity distribution plot of
light reflected off a film substrate for a privacy screen that has
a substrate, an array of square frustums, and a second substrate on
top of the frustums. FIG. 53 shows a radiant intensity distribution
plot of light reflected off a film substrate for a single optical
element.
[0113] In one embodiment, the substrate with frustums is applied to
the display of an e-reader, and the transmitted light is used to
view the e-reader. The light that transmits through the substrate
with frustums illuminates the e-reader display, then reflects off
the e-reader display and passes back through the substrate to the
primary viewer. In this embodiment, the size of the frustums can be
made to match the size of the pixels of the e-reader display and
the array of frustums on the substrate can be aligned with the
array of pixels in the e-reader so as to avoid adverse viewing
effect, such as Moire effects. FIGS. 54-57 show the light incident
on the substrate, which is on an e-reader surface, and the
combination of light, which reflects off the substrate and
transmits through the substrate from the e-reader, after reflecting
off the e-reader. FIG. 54 is a Lambertian reflector with collimated
input. FIG. 55 is a radiant intensity distribution plot of
Lambertian reflector with collimated input. FIG. 56 is radiant
intensity distribution plot of light reflected from film substrate
and Lambertian reflector combined. FIG. 57 is light reflected from
a film substrate and Lambertian reflector combined.
[0114] In another embodiment, the substrate with the frustums is
applied to the screen of a display, such as an LED display, an LCD
display, a computer display, a phone display, a tablet display, or
any other type of electronic display. In this embodiment, the size
of the frustums can be made to match the size of the pixels of the
display, and the array of frustums in the substrate can be aligned
with the array of pixels in the display, so as to avoid Moire
effects. In another embodiment, the frustums are nearly perfectly
aligned with pixels of a display and there are an integer number of
one or more frustums within each pixel pitch. In one embodiment,
the frustums are rectangular frustum and there can be an integer
number of frustums in one axis and an integer number of frustums in
the other axis. The number of frustums in these two axes can be
different but must be integers.
[0115] In another embodiment, the substrate with frustums is
applied to an electronic display, a window, or other viewing
surface, which serves as a privacy screen. The privacy screen for a
display or a window includes an array of frustums positioned on a
substrate wherein an index of refraction of the substrate is
comparable to an index of refraction of the frustum, wherein an
index of refraction of the spaces between the frustums is lower
than the index of refraction of the frustums, and wherein incoming
light is controlled in at least one direction.
[0116] A molding fabrication process allows for simple and large
area fabrication making these arrays applicable to small and large
display applications. In one embodiment of the fabrication process,
the frustums are first patterned in photoresist using a
Direct-Write-Laser (DWL) technique. The thickness of the
photoresist is precisely and uniformly controlled to match the
heights of the frustums that are patterned all the way down to the
substrate. In one embodiment, the tops of the frustums are defined
by the exposed substrate that the photopolymer is on. This provides
a smooth and well-defined top for the frustums and all the frustums
are then coplanar with each other. The DWL toolset uses a rastering
laser beam to expose the entire depth of the resist in one or
several passes. Other conventional photolithographic techniques,
such as Photomask aligners and/or steppers and scanners can also be
used to make these structures using contact or proximity
lithography. The desired frustum angles can be achieved by imaging
in grayscale or by tuning the lithographic process, such as the
exposure conditions. A mold is then made using an electroforming
process after depositing a seed layer on the frustums in resist.
The frustums are then replicated into a transparent flexible or
rigid plate using a mold transfer process.
[0117] In another embodiment, a method of fabricating a flexible or
rigid substrate, which includes an array of microstructures or
nanostructures on one side of the substrate comprises coating a
substrate with a uniform thickness of photoresist polymer; which
includes applying a rastering laser beam to develop and form a
series of identical or non-identical microstructures or
nanostructures wherein the microstructures or nanostructures
comprise frustums or inverse frustums, and wherein the developed
photoresist can be used to make molds, replicas, final parts, or
mixtures thereof.
[0118] In another embodiment, as shown in FIG. 58, a method of
making a master includes obtaining a smooth, flat substrate, such
as glass, placing a photoresist coating on one surface, exposing
the photoresist coating to light in a frustum pattern and removing
the exposed regions of the photoresist. This can be done by a
photolithography process, a mechanical process, such as diamond
turning, or a e-beam etching process. FIG. 58 shows 5 of the steps
in this method from the top of the figure to the bottom of the
figure. The patterned photoresist on the glass substrate is then
used as a master to replicate the frustums. The glass substrate is
exposed in the regions, which will become the tops of the frustums
by completely removing the photoresist in these regions. The master
is used to make copies of the inverse of the pattern of the
photoresist. The tops of the frustums are all flat and co-planar
because they were formed on the exposed surface of the smooth glass
substrate. Therefore, the tops of the frustums of the new part can
be bonded to a second substrate if desired. FIG. 59 shows the
opposite of this situation. FIG. 59 shows 5 of the steps in this
method from the top of the figure to the bottom of the figure in
which the glass substrate is not completely exposed for the tops of
all the frustums, and therefore, the tops of the frustums of the
replicated part from the photoresist master are not co-planar. This
is less desirable when a second substrate is to be bonded to the
tops of all the frustums and the goal is for the tops of the
frustums to have full contact with the second substrate. However,
when it is desirable for a small gap to be present between most of
the frustums and a second substrate, then having a small number of
frustums be formed against the exposed glass substrate and the rest
being less deep and not reaching the glass substrate can be
desirable. In this embodiment, the frustums with tops which are
formed against the glass substrate can be bonded to the second
substrate. The rest of the frustums will have a gap between the top
of the frustums and a second substrate. The frustums which contact
the second substrate will provide a firm point of contact and
create a fixed distance between the rest of the frustums and the
second substrate.
[0119] In another embodiment, the privacy screen can be formed by
the microstructures or nanostructures on a substrate wherein the
microstructures or nanostructures are an inverse surface relief of
frustums. In this embodiment, the inverse surface relief structures
are formed on the substrate and then another material with a higher
index of refraction fills in the surface relief structure. The
inverse surface relief structure has a lower index of refraction
than the material which fills it in. Both materials are transparent
to the wavelengths of light in which the privacy screen operates.
The top surface of the second material which fills in the inverse
surface relief structures is smooth. One advantage of this
embodiment is that air is not needed within the privacy screen.
FIG. 41 shows the sideview of such an embodiment. The green region
is a substrate with a surface relief of inverse frustums. The index
of refraction of the green region is n2 and the index of refraction
of the blue region is n1. The blue region is the second material
that is filled into the inverse frustum surface relief structures.
In this embodiment, n2 is lower than n1.
[0120] Alternative embodiments of the subject matter of this
application will become apparent to one of ordinary skill in the
art to which the present invention pertains without departing from
its spirit and scope. It is to be understood that no limitation
with respect to specific embodiments shown here is intended or
inferred.
* * * * *