U.S. patent application number 16/453881 was filed with the patent office on 2019-10-17 for static multiview display and method.
The applicant listed for this patent is LEIA INC.. Invention is credited to Francesco Aieta, David A. Fattal, Xuejian Li.
Application Number | 20190317265 16/453881 |
Document ID | / |
Family ID | 62791093 |
Filed Date | 2019-10-17 |
United States Patent
Application |
20190317265 |
Kind Code |
A1 |
Fattal; David A. ; et
al. |
October 17, 2019 |
STATIC MULTIVIEW DISPLAY AND METHOD
Abstract
A static multiview display and method of static multiview
display operation provide a static multiview image using
diffractive gratings to diffractively scatter light from guided
light beams having different radial directions. The static
multiview display includes a light guide configured to guide
plurality of guided light beams and a light source configured to
provide the guided light beam plurality having the different radial
directions. The static multiview display further includes a
plurality of diffraction gratings configured to provide from a
portion of the guided light beams directional light beams having
intensities and principal angular directions corresponding to view
pixels of the static multiview image.
Inventors: |
Fattal; David A.; (Mountain
View, CA) ; Li; Xuejian; (Menlo Park, CA) ;
Aieta; Francesco; (Menlo Park, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LEIA INC. |
Menlo Park |
CA |
US |
|
|
Family ID: |
62791093 |
Appl. No.: |
16/453881 |
Filed: |
June 26, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/US2017/053817 |
Sep 27, 2017 |
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16453881 |
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62442982 |
Jan 6, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 27/106 20130101;
G02B 6/0035 20130101; G02B 30/26 20200101; G02B 27/42 20130101;
G02B 6/0068 20130101; G02B 6/003 20130101; G02B 5/1861
20130101 |
International
Class: |
F21V 8/00 20060101
F21V008/00; G02B 5/18 20060101 G02B005/18 |
Claims
1. A static multiview display comprising: a light guide configured
to guide light beams; a light source at an input location on the
light guide, the light source being configured to provide within
the light guide a plurality of guided light beams having different
radial directions from one another; and a plurality of diffraction
gratings configured to emit directional light beams representing a
static multiview image, each diffraction grating being configured
to provide from a portion of a guided light beam of the guided
light beam plurality a directional light beam having an intensity
and a principal angular direction corresponding to an intensity and
a view direction of a view pixel of the static multiview image.
2. The static multiview display of claim 1, wherein the input
location of the light source is on a side of the light guide at
about a midpoint of the side.
3. The static multiview display of claim 1, wherein a grating
characteristic of the diffraction grating is configured to
determine the intensity and the principal angular direction, the
grating characteristic being a function of both a location of the
diffraction grating on a surface of the light guide and the input
location of the light source on a side of the light guide.
4. The static multiview display of claim 3, wherein the grating
characteristic comprises one or both of a grating pitch of the
diffraction grating and a grating orientation of the diffraction
grating, the grating characteristic being configured to determine
the principal angular direction of the directional light beam
provided by the diffraction grating.
5. The static multiview display of claim 3, wherein the grating
characteristic comprises a grating depth configured to determine
the intensity of the directional light beam provided by the
diffraction grating.
6. The static multiview display of claim 1, wherein an emission
pattern of a directional light beam of the directional light beam
plurality is wider in a direction parallel to a direction of
propagation of the guided light beam plurality than in a direction
perpendicular to the direction of propagation of the guided light
beam plurality.
7. The static multiview display of claim 1, wherein the plurality
of diffraction gratings are located on a surface of the light guide
opposite to a light beam emission surface of the light guide.
8. The static multiview display of claim 1, further comprising a
collimator between the light source and the light guide, the
collimator being configured to collimate light emitted by the light
source, the plurality of guided light beams comprising collimated
light beams.
9. The static multiview display of claim 1, further comprising
another light source at another laterally offset input location on
the light guide, the other light source being configured to provide
another plurality of guided light beams, wherein the plurality of
guided light beams and the other plurality of guided light beams
have different radial directions from one another, and wherein
switching between the light source and the other light source is
configured to animate the static multiview image, the static
multiview display being a quasi-static multiview display.
10. The static multiview display of claim 1, wherein the light
guide is transparent to light propagating in a direction orthogonal
a direction of propagation of a guided light beam of the guided
light beam plurality within the light guide.
11. A static multiview display comprising: a plate light guide; a
light source configured to provide a plurality of guided light
beams having different radial directions from one another within
the plate light guide; and an array of multiview pixels configured
to provide a plurality of different views of a static multiview
image, a multiview pixel comprising a plurality of diffraction
gratings configured to diffractively couple out light from the
guided light beam plurality to provide directional light beams
representing view pixels of the multiview pixel, wherein a
principal angular direction of a directional light beam provided by
a diffraction grating of the diffraction grating plurality is a
function of a grating characteristic, the grating characteristic
being a function of a relative location of the diffraction grating
and the light source.
12. The static multiview display of claim 11, wherein the grating
characteristic comprises one or both of a grating pitch and a
grating orientation of the diffraction grating.
13. The static multiview display of claim 11, wherein an intensity
of the directional light beam provided by the diffraction grating
and corresponding to an intensity of a corresponding view pixel is
determined by a diffractive coupling efficiency of the diffraction
grating.
14. The static multiview display of claim 11, wherein the light
source comprises a first optical emitter laterally offset from a
second optical emitter along a side of the light guide, the first
optical emitter being configured to provide a first plurality of
guided light beams and the second optical emitter being configured
to provide a second plurality of guided light beams.
15. The static multiview display of claim 11, wherein the light
guide is transparent in a direction orthogonal to a direction of
propagation of a guided light beam of the guided light beam
plurality within the light guide.
16. A method of static multiview display operation, the method
comprising: guiding in a light guide a plurality of guided light
beams having a common point of origin and different radial
directions from one another; and emitting a plurality of
directional light beams representing a static multiview image using
a plurality of diffraction gratings, a diffraction grating of the
diffraction grating plurality diffractively coupling out light from
the guided light beam plurality as a directional light beam of the
directional light beam plurality having an intensity and a
principal angular direction of a corresponding view pixel of the
static multiview image, wherein the intensity and principal angular
direction of the emitted directional light beam are controlled by a
grating characteristic of the diffraction grating that is based on
a location of the diffraction grating relative to the common origin
point.
17. The method of static multiview display operation of claim 16,
wherein grating characteristic controlling the principal angular
direction comprises one or both of a grating pitch and a grating
orientation of the diffraction grating.
18. The method of static multiview display operation of claim 16,
wherein the grating characteristic controlling the intensity
comprises a grating depth of the diffraction grating.
19. The method of static multiview display operation of claim 16,
further comprising providing light to be guided as the plurality of
guided light beams using a light source, the light source being
located at a side of the light guide, wherein the light source
location is the common origin point of the guided light beam
plurality.
20. The method of static multiview display operation of claim 16,
further comprising animating the static multiview image by guiding
a first plurality of light guided light beams during a first time
period and guiding a second plurality of guided light beams during
a second time period during a second period, the first guided light
beam plurality having a common origin point that differs from a
common origin point of the second guided light beam plurality,
wherein animation comprises a shift in an apparent location of the
static multiview image during the first and second time periods.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation patent application of and
claims the benefit of priority to International Application No.
PCT/US2017/053817, filed Sep. 27, 2017, which claims priority to
U.S. Provisional Patent Application Ser. No. 62/442,982, filed Jan.
6, 2017, the entire contents of which are incorporated by reference
herein.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] N/A
BACKGROUND
[0003] Displays and more particularly `electronic` displays are a
nearly ubiquitous medium for communicating information to users of
a wide variety of devices and products. For example, electronic
displays may be found in various devices and applications
including, but not limited to, mobile telephones (e.g., smart
phones), watches, tablet computes, mobile computers (e.g., laptop
computers), personal computers and computer monitors, automobile
display consoles, camera displays, and various other mobile as well
as substantially non-mobile display applications and devices.
Electronic displays generally employ a differential pattern of
pixel intensity to represent or display an image or similar
information that is being communicated. The differential pixel
intensity pattern may be provided by reflecting light incident on
the display as in the case of passive electronic displays.
Alternatively, the electronic display may provide or emit light to
provide the differential pixel intensity pattern. Electronic
displays that emit light are often referred to as active
displays.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Various features of examples and embodiments in accordance
with the principles described herein may be more readily understood
with reference to the following detailed description taken in
conjunction with the accompanying drawings, where like reference
numerals designate like structural elements, and in which:
[0005] FIG. 1A illustrates a perspective view of a multiview
display in an example, according to an embodiment consistent with
the principles described herein.
[0006] FIG. 1B illustrates a graphical representation of angular
components of a light beam having a particular principal angular
direction corresponding to a view direction of a multiview display
in an example, according to an embodiment consistent with the
principles described herein.
[0007] FIG. 2 illustrates a cross-sectional view of a diffraction
grating in an example, according to an embodiment consistent with
the principles described herein.
[0008] FIG. 3A illustrates a plan view of a static multiview
display in an example, according to an embodiment consistent with
the principles described herein.
[0009] FIG. 3B illustrates a cross-sectional view of a portion of a
static multiview display in an example, according to an embodiment
consistent with the principles described herein.
[0010] FIG. 3C illustrates a perspective view of a static multiview
display in an example, according to an embodiment consistent with
the principles described herein.
[0011] FIG. 4 illustrates a plan view of a static multiview display
in an example, according to an embodiment consistent with the
principles described herein.
[0012] FIG. 5A illustrates a plan view of a static multiview
display including spurious reflection mitigation in an example,
according to an embodiment consistent with the principles described
herein.
[0013] FIG. 5B illustrates a plan view of a static multiview
display including spurious reflection mitigation in an example,
according to another embodiment consistent with the principles
described herein.
[0014] FIG. 6A illustrates a plan view of a multiview display in an
example, according to an embodiment consistent with the principles
described herein.
[0015] FIG. 6B illustrates a plan view of the static multiview
display of FIG. 6A in another example, according to an embodiment
consistent with the principles described herein.
[0016] FIG. 7A illustrates a plan view of a diffraction grating of
a multiview display in an example, according to an embodiment
consistent with the principles described herein.
[0017] FIG. 7B illustrates a plan view of a set diffraction
gratings organized as a multiview pixel in an example, according to
another embodiment consistent with the principles described
herein.
[0018] FIG. 8 illustrates a block diagram of a static multiview
display in an example, according to an embodiment consistent with
the principles described herein.
[0019] FIG. 9 illustrates a flow chart of a method of static
multiview display operation in an example, according to an
embodiment consistent with the principles described herein.
[0020] Certain examples and embodiments have other features that
are one of in addition to and in lieu of the features illustrated
in the above-referenced figures. These and other features are
detailed below with reference to the above-referenced figures.
DETAILED DESCRIPTION
[0021] Examples and embodiments in accordance with the principles
described herein provide display of a static or quasi-static
three-dimensional (3D) or multiview image. In particular,
embodiments consistent with the principles described display the
static or quasi-static multiview image using a plurality of
directional light beams. The individual intensities and directions
of directional light beams of the directional light beam plurality,
in turn, correspond to various view pixels in views of the
multiview image being displayed. According to various embodiments,
the individual intensities and, in some embodiments, the individual
directions of the directional light beams are predetermined or
`fixed.` As such, the displayed multiview image may be referred to
as a static or quasi-static multiview image.
[0022] According to various embodiments, a static multiview display
configured to display the static or quasi-static multiview image
comprises diffraction gratings optically connected to a light guide
to provide the directional light beams having the individual
directional light beam intensities and directions. The diffraction
gratings are configured to emit or provide the directional light
beams by or according to diffractive coupling or scattering out of
light guided from within the light guide, the light being guided as
a plurality of guided light beams. Further, guided light beams of
the guided light beam plurality are guided within the light guide
at different radial directions from one another. As such, a
diffraction grating of the diffraction grating plurality comprises
a grating characteristic that accounts for or that is a function of
a particular radial direction of a guided light beam incident on
the diffraction grating. In particular, the grating characteristic
may be a function of a relative location of the diffraction grating
and a light source configured to provide the guided light beam.
According to various embodiments, the grating characteristic is
configured to account for the radial direction of the guided light
beam to insure a correspondence between the emitted directional
light beams provide by the diffraction gratings and associated view
pixels in various views of the static or quasi-static multiview
image being displayed.
[0023] Herein, a `multiview display` is defined as an electronic
display or display system configured to provide different views of
a multiview image in different view directions. A `static multiview
display` is a defined as a multiview display configured to display
a predetermined or fixed (i.e., static) multiview image, albeit as
a plurality of different views. A `quasi-static multiview display`
is defined herein as a static multiview display that may be
switched between different fixed multiview images or between a
plurality of multiview image states, typically as a function of
time. Switching between the different fixed multiview images or
multiview image states may provide a rudimentary form of animation,
for example. Further, as defined herein, a quasi-static multiview
display is a type of static multiview display. As such, no
distinction is made between a purely static multiview display or
image and a quasi-static multiview display or image, unless such
distinction is necessary for proper understanding.
[0024] FIG. 1A illustrates a perspective view of a multiview
display 10 in an example, according to an embodiment consistent
with the principles described herein. As illustrated in FIG. 1A,
the multiview display 10 comprises a diffraction grating on a
screen 12 configured to display a view pixel in a view 14 within or
of a multiview image 16 (or equivalently a view 14 of the multiview
display 10). The screen 12 may be a display screen of an
automobile, a telephone (e.g., mobile telephone, smart phone,
etc.), a tablet computer, a laptop computer, a computer monitor of
a desktop computer, a camera display, or an electronic display of
substantially any other device, for example.
[0025] The multiview display 10 provides different views 14 of the
multiview image 16 in different view directions 18 (i.e., in
different principal angular directions) relative to the screen 12.
The view directions 18 are illustrated as arrows extending from the
screen 12 in various different principal angular directions. The
different views 14 are illustrated as shaded polygonal boxes at the
termination of the arrows (i.e., depicting the view directions 18).
Thus, when the multiview display 10 (e.g., as illustrated in FIG.
1A) is rotated about the y-axis, a viewer sees different views 14.
On the other hand (as illustrated) when the multiview display 10 in
FIG. 1A is rotated about the x-axis the viewed image is unchanged
until no light reaches the viewer's eyes (as illustrated).
[0026] Note that, while the different views 14 are illustrated as
being above the screen 12, the views 14 actually appear on or in a
vicinity of the screen 12 when the multiview image 16 is displayed
on the multiview display 10 and viewed by the viewer. Depicting the
views 14 of the multiview image 16 above the screen 12 as in FIG.
1A is done only for simplicity of illustration and is meant to
represent viewing the multiview display 10 from a respective one of
the view directions 18 corresponding to a particular view 14.
Further, in FIG. 1A only three views 14 and three view directions
18 are illustrated, all by way of example and not limitation.
[0027] A view direction or equivalently a light beam having a
direction corresponding to a view direction of a multiview display
generally has a principal angular direction given by angular
components {.theta., .PHI.}, by definition herein. The angular
component .theta. is referred to herein as the `elevation
component` or `elevation angle` of the light beam. The angular
component .PHI. is referred to as the `azimuth component` or
`azimuth angle` of the light beam. By definition, the elevation
angle .theta. is an angle in a vertical plane (e.g., perpendicular
to a plane of the multiview display screen while the azimuth angle
.PHI. is an angle in a horizontal plane (e.g., parallel to the
multiview display screen plane).
[0028] FIG. 1B illustrates a graphical representation of the
angular components {.theta., .PHI.} of a light beam 20 having a
particular principal angular direction corresponding to a view
direction (e.g., view direction 18 in FIG. 1A) of a multiview
display in an example, according to an embodiment consistent with
the principles described herein. In addition, the light beam 20 is
emitted or emanates from a particular point, by definition herein.
That is, by definition, the light beam 20 has a central ray
associated with a particular point of origin within the multiview
display. FIG. 1B also illustrates the light beam (or view
direction) point of origin O.
[0029] Further herein, the term `multiview` as used in the terms
`multiview image` and `multiview display` is defined as a plurality
of views representing different perspectives or including angular
disparity between views of the view plurality. In addition, herein
the term `multiview` explicitly includes more than two different
views (i.e., a minimum of three views and generally more than three
views), by definition herein. As such, `multiview display` as
employed herein is explicitly distinguished from a stereoscopic
display that includes only two different views to represent a scene
or an image. Note however, while multiview images and multiview
displays may include more than two views, by definition herein,
multiview images may be viewed (e.g., on a multiview display) as a
stereoscopic pair of images by selecting only two of the multiview
views to view at a time (e.g., one view per eye).
[0030] In the multiview display, a `multiview pixel` is defined
herein as a set or plurality of view pixels representing pixels in
each of a similar plurality of different views of a multiview
display. Equivalently, a multiview pixel may have an individual
view pixel corresponding to or representing a pixel in each of the
different views of the multiview image to be displayed by the
multiview display. Moreover, the view pixels of the multiview pixel
are so-called `directional pixels` in that each of the view pixels
is associated with a predetermined view direction of a
corresponding one of the different views, by definition herein.
Further, according to various examples and embodiments, the
different view pixels represented by the view pixels of a multiview
pixel may have equivalent or at least substantially similar
locations or coordinates in each of the different views. For
example, a first multiview pixel may have individual view pixels
corresponding to view pixels located at {x.sub.1, y.sub.1} in each
of the different views of a multiview image, while a second
multiview pixel may have individual view pixels corresponding to
view pixels located at {x.sub.2, y.sub.2} in each of the different
views, and so on.
[0031] In some embodiments, a number of view pixels in a multiview
pixel may be equal to a number of views of the multiview display.
For example, the multiview pixel may provide eight (8) view pixels
associated with a multiview display having 8 different views.
Alternatively, the multiview pixel may provide sixty-four (64) view
pixels associated with a multiview display having 64 different
views. In another example, the multiview display may provide an
eight by four array of views (i.e., 32 views) and the multiview
pixel may include thirty-two 32 view pixels (i.e., one for each
view). Further, according to some embodiments, a number of
multiview pixels of the multiview display may be substantially
equal to a number of pixels that make up a selected view of the
multiview display.
[0032] Herein, a `light guide` is defined as a structure that
guides light within the structure using total internal reflection.
In particular, the light guide may include a core that is
substantially transparent at an operational wavelength of the light
guide. In various examples, the term `light guide` generally refers
to a dielectric optical waveguide that employs total internal
reflection to guide light at an interface between a dielectric
material of the light guide and a material or medium that surrounds
that light guide. By definition, a condition for total internal
reflection is that a refractive index of the light guide is greater
than a refractive index of a surrounding medium adjacent to a
surface of the light guide material. In some embodiments, the light
guide may include a coating in addition to or instead of the
aforementioned refractive index difference to further facilitate
the total internal reflection. The coating may be a reflective
coating, for example. The light guide may be any of several light
guides including, but not limited to, one or both of a plate or
slab guide and a strip guide.
[0033] Further herein, the term `plate` when applied to a light
guide as in a `plate light guide` is defined as a piece-wise or
differentially planar layer or sheet, which is sometimes referred
to as a `slab` guide. In particular, a plate light guide is defined
as a light guide configured to guide light in two substantially
orthogonal directions bounded by a top surface and a bottom surface
(i.e., opposite surfaces) of the light guide. Further, by
definition herein, the top and bottom surfaces are both separated
from one another and may be substantially parallel to one another
in at least a differential sense. That is, within any
differentially small section of the plate light guide, the top and
bottom surfaces are substantially parallel or co-planar.
[0034] In some embodiments, the plate light guide may be
substantially flat (i.e., confined to a plane) and therefore, the
plate light guide is a planar light guide. In other embodiments,
the plate light guide may be curved in one or two orthogonal
dimensions. For example, the plate light guide may be curved in a
single dimension to form a cylindrical shaped plate light guide.
However, any curvature has a radius of curvature sufficiently large
to ensure that total internal reflection is maintained within the
plate light guide to guide light.
[0035] Herein, a `diffraction grating` is generally defined as a
plurality of features (i.e., diffractive features) arranged to
provide diffraction of light incident on the diffraction grating.
In some examples, the plurality of features may be arranged in a
periodic or quasi-periodic manner having one or more grating
spacings between pairs of the features. For example, the
diffraction grating may comprise a plurality of features (e.g., a
plurality of grooves or ridges in a material surface) arranged in a
one-dimensional (1D) array. In other examples, the diffraction
grating may be a two-dimensional (2D) array of features. The
diffraction grating may be a 2D array of bumps on or holes in a
material surface, for example. According to various embodiments and
examples, the diffraction grating may be a sub-wavelength grating
having a grating spacing or distance between adjacent diffractive
features that is less than about a wavelength of light that is to
be diffracted by the diffraction grating.
[0036] As such, and by definition herein, the `diffraction grating`
is a structure that provides diffraction of light incident on the
diffraction grating. If the light is incident on the diffraction
grating from a light guide, the provided diffraction or diffractive
scattering may result in, and thus be referred to as, `diffractive
coupling` in that the diffraction grating may couple light out of
the light guide by diffraction. The diffraction grating also
redirects or changes an angle of the light by diffraction (i.e., at
a diffractive angle). In particular, as a result of diffraction,
light leaving the diffraction grating generally has a different
propagation direction than a propagation direction of the light
incident on the diffraction grating (i.e., incident light). The
change in the propagation direction of the light by diffraction is
referred to as `diffractive redirection` herein. Hence, the
diffraction grating may be understood to be a structure comprising
diffractive features that diffractively redirects light incident on
the diffraction grating and, if the light is incident from a light
guide, the diffraction grating may also diffractively couple out
the light from the light guide.
[0037] Further, by definition herein, the features of a diffraction
grating are referred to as `diffractive features` and may be one or
more of at, in and on a material surface (i.e., a boundary between
two materials). The surface may be a surface of a light guide, for
example. The diffractive features may include any of a variety of
structures that diffract light including, but not limited to, one
or more of grooves, ridges, holes and bumps at, in or on the
surface. For example, the diffraction grating may include a
plurality of substantially parallel grooves in the material
surface. In another example, the diffraction grating may include a
plurality of parallel ridges rising out of the material surface.
The diffractive features (e.g., grooves, ridges, holes, bumps,
etc.) may have any of a variety of cross-sectional shapes or
profiles that provide diffraction including, but not limited to,
one or more of a sinusoidal profile, a rectangular profile (e.g., a
binary diffraction grating), a triangular profile and a saw tooth
profile (e.g., a blazed grating).
[0038] As described further below, a diffraction grating herein may
have a grating characteristic, including one or more of a feature
spacing or pitch, an orientation and a size (such as a width or
length of the diffraction grating). Further, the grating
characteristic may selected or chosen to be a function of the angle
of incidence of light beams on the diffraction grating, a distance
of the diffraction grating from a light source or both. In
particular, the grating characteristic of a diffraction grating may
be chosen to depend on a relative location of the light source and
a location of the diffraction grating, according to some
embodiments. By appropriately varying the grating characteristic of
the diffraction grating, both an intensity and a principal angular
direction of a light beam diffracted (e.g., diffractively
coupled-out of a light guide) by the diffraction grating (i.e., a
`directional light beam`) corresponds to an intensity and a view
direction of a view pixel of the multiview image.
[0039] According to various examples described herein, a
diffraction grating (e.g., a diffraction grating of a multiview
pixel, as described below) may be employed to diffractively scatter
or couple light out of a light guide (e.g., a plate light guide) as
a light beam. In particular, a diffraction angle .theta..sub.m of
or provided by a locally periodic diffraction grating may be given
by equation (1) as:
.theta. m = sin - 1 ( n sin .theta. i - m .lamda. d ) ( 1 )
##EQU00001##
where .lamda. is a wavelength of the light, m is a diffraction
order, n is an index of refraction of a light guide, d is a
distance or spacing between features of the diffraction grating,
.theta..sub.i is an angle of incidence of light on the diffraction
grating. For simplicity, equation (1) assumes that the diffraction
grating is adjacent to a surface of the light guide and a
refractive index of a material outside of the light guide is equal
to one (i.e., n.sub.out=1). In general, the diffraction order m is
given by an integer. A diffraction angle .theta..sub.m of a light
beam produced by the diffraction grating may be given by equation
(1) where the diffraction order is positive (e.g., m>0). For
example, first-order diffraction is provided when the diffraction
order m is equal to one (i.e., m=1).
[0040] FIG. 2 illustrates a cross-sectional view of a diffraction
grating 30 in an example, according to an embodiment consistent
with the principles described herein. For example, the diffraction
grating 30 may be located on a surface of a light guide 40. In
addition, FIG. 2 illustrates a light beam (or a collection of light
beams) 50 incident on the diffraction grating 30 at an incident
angle .theta..sub.i. The light beam 50 is a guided light beam
within the light guide 40. Also illustrated in FIG. 2 is a
coupled-out light beam (or a collection of light beams) 60
diffractively produced and coupled-out by the diffraction grating
30 as a result of diffraction of the incident light beam 50. The
coupled-out light beam 60 has a diffraction angle .theta..sub.m (or
`principal angular direction` herein) as given by equation (1). The
coupled-out light beam 60 may correspond to a diffraction order `m`
of the diffraction grating 30, for example.
[0041] According to various embodiments, the principal angular
direction of the various light beams is determined by the grating
characteristic including, but not limited to, one or more of a size
(e.g., a length, a width, an area, etc.) of the diffraction
grating, an orientation, and a feature spacing. Further, a light
beam produced by the diffraction grating has a principal angular
direction given by angular components {.theta., .PHI.}, by
definition herein, and as described above with respect to FIG.
1B.
[0042] Herein, a `collimated light` or `collimated light beam` is
generally defined as a beam of light in which rays of the light
beam are substantially parallel to one another within the light
beam (e.g., the guided light beam in the light guide). Further,
rays of light that diverge or are scattered from the collimated
light beam are not considered to be part of the collimated light
beam, by definition herein. Moreover, herein a `collimator` is
defined as substantially any optical device or apparatus that is
configured to collimate light.
[0043] Herein, a `collimation factor` is defined as a degree to
which light is collimated. In particular, a collimation factor
defines an angular spread of light rays within a collimated beam of
light, by definition herein. For example, a collimation factor
.sigma. may specify that a majority of light rays in a beam of
collimated light is within a particular angular spread (e.g.,
+/-.sigma. degrees about a central or principal angular direction
of the collimated light beam). The light rays of the collimated
light beam may have a Gaussian distribution in terms of angle and
the angular spread be an angle determined by at one-half of a peak
intensity of the collimated light beam, according to some
examples.
[0044] Herein, a `light source` is defined as a source of light
(e.g., an optical emitter configured to produce and emit light).
For example, the light source may comprise an optical emitter such
as a light emitting diode (LED) that emits light when activated or
turned on. In particular, herein the light source may be
substantially any source of light or comprise substantially any
optical emitter including, but not limited to, one or more of a
light emitting diode (LED), a laser, an organic light emitting
diode (OLED), a polymer light emitting diode, a plasma-based
optical emitter, a fluorescent lamp, an incandescent lamp, and
virtually any other source of light. The light produced by the
light source may have a color (i.e., may include a particular
wavelength of light), or may be a range of wavelengths (e.g., white
light). In some embodiments, the light source may comprise a
plurality of optical emitters. For example, the light source may
include a set or group of optical emitters in which at least one of
the optical emitters produces light having a color, or equivalently
a wavelength, that differs from a color or wavelength of light
produced by at least one other optical emitter of the set or group.
The different colors may include primary colors (e.g., red, green,
blue) for example.
[0045] Further, as used herein, the article `a` is intended to have
its ordinary meaning in the patent arts, namely `one or more`. For
example, `a diffraction grating` means one or more diffraction
gratings and as such, `the diffraction grating` means `the
diffraction grating(s)` herein. Also, any reference herein to
`top`, `bottom`, `upper`, `lower`, `up`, `down`, `front`, back`,
`first`, `second`, `left` or `right` is not intended to be a
limitation herein. Herein, the term `about` when applied to a value
generally means within the tolerance range of the equipment used to
produce the value, or may mean plus or minus 10%, or plus or minus
5%, or plus or minus 1%, unless otherwise expressly specified.
Further, the term `substantially` as used herein means a majority,
or almost all, or all, or an amount within a range of about 51% to
about 100%. Moreover, examples herein are intended to be
illustrative only and are presented for discussion purposes and not
by way of limitation.
[0046] According to some embodiments of the principles described
herein, a multiview display configured to provide multiview images
and more particularly static multiview images (i.e., a static
multiview display) is provided. FIG. 3A illustrates a plan view of
a static multiview display 100 in an example, according to an
embodiment consistent with the principles described herein. FIG. 3B
illustrates a cross-sectional view of a portion of a static
multiview display 100 in an example, according to an embodiment
consistent with the principles described herein. In particular,
FIG. 3B may illustrate a cross section through a portion of the
static multiview display 100 of FIG. 3A, the cross section being in
an x-z plane. FIG. 3C illustrates a perspective view of a static
multiview display 100 in an example, according to an embodiment
consistent with the principles described herein. According to some
embodiments, the illustrated static multiview display 100 is
configured to provide purely a static multiview image, while in
others the static multiview display 100 may be configured to
provide a plurality of multiview images and therefore functions as
(or is) a quasi-static multiview display 100. For example, the
static multiview display 100 may be switchable between different
fixed multiview images or equivalently between a plurality of
multiview image states, as described below.
[0047] The static multiview display 100 illustrated in FIGS. 3A-3C
is configured to provide a plurality of directional light beams
102, each directional light beam 102 of the plurality having an
intensity and a principal angular direction. Together, the
plurality of directional light beams 102 represents various view
pixels of a set of views of a multiview image that the static
multiview display 100 is configured to provide or display. In some
embodiments, the view pixels may be organized into multiview pixels
to represent the various different views of the multiview
images.
[0048] As illustrated, the static multiview display 100 comprises a
light guide 110. The light guide may be a plate light guide (as
illustrated), for example. The light guide 110 is configured to
guide light along a length of the light guide 110 as guided light
or more particularly as guided light beams 112. For example, the
light guide 110 may include a dielectric material configured as an
optical waveguide. The dielectric material may have a first
refractive index that is greater than a second refractive index of
a medium surrounding the dielectric optical waveguide. The
difference in refractive indices is configured to facilitate total
internal reflection of the guided light beams 112 according to one
or more guided modes of the light guide 110, for example.
[0049] In some embodiments, the light guide 110 may be a slab or
plate optical waveguide comprising an extended, substantially
planar sheet of optically transparent, dielectric material. The
substantially planar sheet of dielectric material is configured to
guide the guided light beams 112 using total internal reflection.
According to various examples, the optically transparent material
of the light guide 110 may include or be made up of any of a
variety of dielectric materials including, but not limited to, one
or more of various types of glass (e.g., silica glass,
alkali-aluminosilicate glass, borosilicate glass, etc.) and
substantially optically transparent plastics or polymers (e.g.,
poly(methyl methacrylate) or `acrylic glass`, polycarbonate, etc.).
In some examples, the light guide 110 may further include a
cladding layer (not illustrated) on at least a portion of a surface
(e.g., one or both of the top surface and the bottom surface) of
the light guide 110. The cladding layer may be used to further
facilitate total internal reflection, according to some
examples.
[0050] According to various embodiments, the light guide 110 is
configured to guide the guided light beams 112 according to total
internal reflection at a non-zero propagation angle between a first
surface 110' (e.g., a `front` surface) and a second surface 110''
(e.g., a `back` or `bottom` surface) of the light guide 110. In
particular, the guided light beams 112 propagate by reflecting or
`bouncing` between the first surface 110' and the second surface
110'' of the light guide 110 at the non-zero propagation angle.
Note, the non-zero propagation angle is not explicitly depicted in
FIG. 3B for simplicity of illustration. However, FIG. 3B does
illustrate an arrow pointing into a plane of the illustration
depicting a general propagation direction 103 of the guided light
beams 112 along the light guide length.
[0051] As defined herein, a `non-zero propagation angle` is an
angle relative to a surface (e.g., the first surface 110' or the
second surface 110'') of the light guide 110. Further, the non-zero
propagation angle is both greater than zero and less than a
critical angle of total internal reflection within the light guide
110, according to various embodiments. For example, the non-zero
propagation angle of the guided light beam 112 may be between about
ten (10) degrees and about fifty (50) degrees or, in some examples,
between about twenty (20) degrees and about forty (40) degrees, or
between about twenty-five (25) degrees and about thirty-five (35)
degrees. For example, the non-zero propagation angle may be about
thirty (30) degrees. In other examples, the non-zero propagation
angle may be about 20 degrees, or about 25 degrees, or about 35
degrees. Moreover, a specific non-zero propagation angle may be
chosen (e.g., arbitrarily) for a particular implementation as long
as the specific non-zero propagation angle is chosen to be less
than the critical angle of total internal reflection within the
light guide 110.
[0052] As illustrated in FIGS. 3A and 3C, the static multiview
display 100 further comprise a light source 120. The light source
120 is located at an input location 116 on the light guide 110. For
example, the light source 120 may be located adjacent to an edge or
side 114 of the light guide 110, as illustrated. The light source
120 is configured to provide light within the light guide 110 as
the plurality of guided light beams 112. Further, the light source
120 provides the light such that individual guided light beams 112
of the guided light beam plurality have different radial directions
118 from one another.
[0053] In particular, light emitted by the light source 120 is
configured enter the light guide 110 and to propagate as the
plurality of guided light beams 112 in a radial pattern away from
the input location 116 and across or along a length of the light
guide 110. Further, the individual guided light beams 112 of the
guided light beam plurality have different radial directions from
one another by virtue of the radial pattern of propagation away
from the input location 116. For example, the light source 120 may
be butt-coupled to the side 114. The light source 120 being
butt-coupled may facilitate introduction of light in a fan-shape
pattern to provide the different radial directions of the
individual guided light beams 112, for example. According to some
embodiments, the light source 120 may be or at least approximate a
`point` source of light at the input location 116 such that the
guided light beams 112 propagate along the different radial
directions 118 (i.e., as the plurality of guided light beams
112).
[0054] In some embodiments, the input location 116 of the light
source 120 is on a side 114 of the light guide 110 near or about at
a center or a middle of the side 114. In particular, in FIGS. 3A
and 3C, the light source 120 is illustrated at an input location
116 that is approximately centered on (e.g., at a middle of) the
side 114 (i.e., the `input side`) of the light guide 110.
Alternatively (not illustrated), the input location 116 may be away
from the middle of the side 114 of the light guide 110. For
example, the input location 116 may be at a corner of the light
guide 110. For example, the light guide 110 may have a rectangular
shape (e.g., as illustrated) and the input location 116 of the
light source 120 may be at a corner of the rectangular-shaped light
guide 110 (e.g., a corner of the input side 114).
[0055] In various embodiments, the light source 120 may comprise
substantially any source of light (e.g., optical emitter)
including, but not limited to, one or more light emitting diodes
(LEDs) or a laser (e.g., laser diode). In some embodiments, the
light source 120 may comprise an optical emitter configured produce
a substantially monochromatic light having a narrowband spectrum
denoted by a particular color. In particular, the color of the
monochromatic light may be a primary color of a particular color
space or color model (e.g., an RGB color model). In other examples,
the light source 120 may be a substantially broadband light source
configured to provide substantially broadband or polychromatic
light. For example, the light source 120 may provide white light.
In some embodiments, the light source 120 may comprise a plurality
of different optical emitters configured to provide different
colors of light. The different optical emitters may be configured
to provide light having different, color-specific, non-zero
propagation angles of the guided light corresponding to each of the
different colors of light.
[0056] In some embodiments, the guided light beams 112 produced by
coupling light from the light source 120 into the light guide 110
may be uncollimated or at least substantially uncollimated. In
other embodiments, the guided light beams 112 may be collimated
(i.e., the guided light beams 112 may be collimated light beams).
As such, in some embodiments, the static multiview display 100 may
include a collimator (not illustrated) between the light source 120
and the light guide 110. Alternatively, the light source 120 may
further comprise a collimator. The collimator is configured to
provide guided light beams 112 within the light guide 110 that are
collimated. In particular, the collimator is configured to receive
substantially uncollimated light from one or more of the optical
emitters of the light source 120 and to convert the substantially
uncollimated light into collimated light. In some examples, the
collimator may be configured to provide collimation in a plane
(e.g., a `vertical` plane) that is substantially perpendicular to
the propagation direction of the guided light beams 112. That is,
the collimation may provide collimated guided light beams 112
having a relatively narrow angular spread in a plane perpendicular
to a surface of the light guide 110 (e.g., the first or second
surface 110', 110''), for example. According to various
embodiments, the collimator may comprise any of a variety of
collimators including, but not limited to a lens, a reflector or
mirror (e.g., tilted collimating reflector), or a diffraction
grating (e.g., a diffraction grating-based barrel collimator)
configured to collimate the light, e.g., from the light source
120.
[0057] Further, in some embodiments, the collimator may provide
collimated light one or both of having the non-zero propagation
angle and being collimated according to a predetermined collimation
factor. Moreover, when optical emitters of different colors are
employed, the collimator may be configured to provide the
collimated light having one or both of different, color-specific,
non-zero propagation angles and having different color-specific
collimation factors. The collimator is further configured to
communicate the collimated light to the light guide 110 to
propagate as the guided light beams 112, in some embodiments.
[0058] Use of collimated or uncollimated light may impact the
multiview image that may be provided by the static multiview
display 100, in some embodiments. For example, if the guided light
beams 112 are collimated within the light guide 110, the emitted
directional light beams 102 may have a relatively narrow or
confined angular spread in at least two orthogonal directions.
Thus, the static multiview display 100 may provide a multiview
image having a plurality of different views in an array having two
different directions (e.g., an x-direction and a y-direction).
However, if the guided light beams 112 are substantially
uncollimated, the multiview image may provide view parallax, but
may not provide a full, two-dimensional array of different views.
In particular, if the guided light beams 112 are uncollimated
(e.g., along the z-axis), the multiview image may provide different
multiview images exhibiting `parallax 3D` when rotated about the
y-axis (e.g., as illustrated in FIG. 1A). On the other hand, if the
static multiview display 100 is rotated around the x-axis, for
example, the multiview image and views thereof may remain
substantially unchanged or the same because the directional light
beams 102 of the directional light beam plurality have a broad
angular range within the y-z plane. Thus, the multiview image
provided may be `parallax only` providing an array of views in only
one direction and not two.
[0059] The static multiview display 100 illustrated in FIGS. 3A-3C
further comprises a plurality of diffraction gratings 130
configured to emit directional light beams 102 of the directional
light beam plurality. As mentioned above and according to various
embodiments, the directional light beams 102 emitted by the
plurality of diffraction gratings 130 may represent a multiview
image. In particular, the directional light beams 102 emitted by
the plurality of diffraction gratings 130 may be configured to
create the multiview image to display information, e.g.,
information having 3D content. Further, the diffraction gratings
130 may emit the directional light beams 102 when the light guide
110 is illuminated from the side 114 by the light source 120, as is
further described below.
[0060] According to various embodiments, a diffraction grating 130
of the diffraction grating plurality are configured to provide from
a portion of a guided light beam 112 of the guided light beam
plurality a directional light beam 102 of the directional light
beam plurality. Further, the diffraction grating 130 is configured
to provide the directional light beam 102 having both an intensity
and a principal angular direction corresponding to an intensity and
a view direction of a view pixel of the multiview image. In some
embodiments, the diffraction gratings 130 of the diffraction
grating plurality generally do not intersect, overlap or otherwise
touch one another, according to some embodiments. That is, each
diffraction grating 130 of the diffraction grating plurality is
generally distinct and separated from other ones of the diffraction
gratings 130, according to various embodiments.
[0061] As illustrated in FIG. 3B, the directional light beams 102
may, at least in part, propagate in a direction that differs from
and in some embodiments is orthogonal to an average or general
propagation direction 103 of a guided light beams 112 within the
light guide 110. For example, as illustrated in FIG. 3B, the
directional light beam 102 from a diffraction grating 130 may be
substantially confined to the x-z plane, according to some
embodiments.
[0062] According to various embodiments, each of the diffraction
gratings 130 of the diffraction grating plurality has an associated
grating characteristic. The associated grating characteristic of
each diffraction grating depends on, is defined by, or is a
function of a radial direction 118 of the guided light beam 112
incident on the diffraction grating from the light source 120.
Further, in some embodiment, the associated grating characteristic
is further determined or defined by a distance between the
diffraction grating 130 and the input location 116 of the light
source 120. For example, the associated characteristic may be a
function of the distance D between diffraction grating 130a and
input location 116 and the radial direction 118a of the guided
light beam 112 incident on the diffraction grating 130a, as
illustrated in FIG. 3A. Stated differently, an associated grating
characteristic of a diffraction grating 130 in the plurality of the
diffraction gratings 130 depends on the input location 116 of the
light source and a particular location of the diffraction grating
130 on a surface of the light guide 110 relative to the input
location 116.
[0063] FIG. 3A illustrates two different diffraction gratings 130a
and 130b having different spatial coordinates (x.sub.1, y.sub.1)
and (x.sub.2, y.sub.2), which further have different grating
characteristics to compensate or account for the different radial
directions 118a and 118b of the plurality of guided light beams 112
from the light source 120 that are incident on the diffraction
gratings 130. Similarly, the different grating characteristics of
the two different diffraction gratings 130a and 130b account for
different distances of the respective diffraction gratings 130a,
130b from the light source input location 116 determined by the
different spatial coordinates (x.sub.1, y.sub.1) and (x.sub.2,
y.sub.2).
[0064] FIG. 3C illustrates an example of a plurality of directional
light beams 102 that may be provided by the static multiview
display 100. In particular, as illustrated, different sets of
diffraction gratings 130 of the diffraction grating plurality are
illustrated emitting directional light beams 102 having different
principal angular directions from one another. The different
principal angular directions may correspond to different view
directions of the static multiview display 100, according to
various embodiments. For example, a first set of the diffraction
gratings 130 may diffractively couple out portions of incident
guided light beams 112 (illustrated as dashed lines) to provide a
first set of directional light beams 102' having a first principal
angular direction corresponding to a first view direction (or a
first view) of the static multiview display 100. Similarly, a
second set of directional light beams 102'' and a third set of
directional light beams 102''' having principal angular directions
corresponding to a second view direction (or a second view) and a
third view direction (or third view), respectively of the static
multiview display 100 may be provided by diffractive coupling out
of portions of incident guided light beams 112 by respective second
third sets of diffraction gratings 130, and so on, as illustrated.
Also illustrated in FIG. 3C are a first view 14', a second view
14'', and a third view 14''', of a multiview image 16 that may be
provided by the multiview display 100. The illustrated first,
second, and third views 14', 14'', 14''', represent different
perspective views of an object and collectively are the displayed
multiview image 16 (e.g., equivalent to the multiview image 16
illustrated in FIG. 1A).
[0065] In general, the grating characteristic of a diffraction
grating 130 may include one or more of a diffractive feature
spacing or pitch, a grating orientation and a grating size (or
extent) of the diffraction grating. Further, in some embodiments, a
diffraction-grating coupling efficiency (such as the
diffraction-grating area, the groove depth or ridge height, etc.)
may be a function of the distance from the input location 116 to
the diffraction grating. For example, the diffraction grating
coupling efficiency may be configured to increase as a function of
distance, in part, to correct or compensate for a general decrease
in the intensity of the guided light beams 112 associated with the
radial spreading and other loss factors. Thus, an intensity of the
directional light beam 102 provided by the diffraction grating 130
and corresponding to an intensity of a corresponding view pixel may
be determined, in part, by a diffractive coupling efficiency of the
diffraction grating 130, according to some embodiments.
[0066] FIG. 4 illustrates a plan view of a static multiview display
100 in an example, according to an embodiment consistent with the
principles described herein. In FIG. 4, illumination volumes 134 in
an angular space that is a distance D from input location 116 of
the light source 120 at the side 114 of the light guide 110 are
shown. Note that the illumination volume has a wider angular size
as the radial direction of propagation of the plurality of guided
light beams 112 changes in angle away from the y-axis and towards
the x-axis. For example, illumination volume 134b is wider than
illumination volume 134a, as illustrated.
[0067] Referring again to FIG. 3B, the plurality of diffraction
gratings 130 may be located at or adjacent to the first surface
110' of the light guide 110, which is the light beam emission
surface of the light guide 110, as illustrated. For example, the
diffraction gratings 130 may be transmission mode diffraction
gratings configured to diffractively couple out the guided light
portion through the first surface 110' as the directional light
beams 102. Alternatively, the plurality of diffraction gratings 130
may be located at or adjacent to the second surface 110'' opposite
from a light beam emission surface of the light guide 110 (i.e.,
the first surface 110'). In particular, the diffraction gratings
130 may be reflection mode diffraction gratings. As reflection mode
diffraction gratings, the diffraction gratings 130 are configured
to both diffract the guided light portion and to reflect the
diffracted guided light portion toward the first surface 110' to
exit through the first surface 110' as the diffractively scattered
or coupled-out directional light beams 102. In other embodiments
(not illustrated), the diffraction gratings 130 may be located
between the surfaces of the light guide 110, e.g., as one or both
of a transmission mode diffraction grating and a reflection mode
diffraction grating.
[0068] In some embodiments described herein, the principal angular
directions of the directional light beams 102 may include an effect
of refraction due to the directional light beams 102 exiting the
light guide 110 at a light guide surface. For example, when the
diffraction gratings 130 are located at or adjacent to second
surface 110'', the directional light beams 102 may be refracted
(i.e., bent) because of a change in refractive index as the
directional light beams 102 cross the first surface 110', by way of
example and not limitation.
[0069] In some embodiments, provision may be made to mitigate, and
in some instances even substantially eliminate, various sources of
spurious reflection of the guided light beams 112 within the static
multiview display 100, especially when those spurious reflection
sources may result in emission of unintended direction light beams
and, in turn, the production of unintended images by static
multiview display 100. Examples of various potential spurious
reflection sources include, but not limited to, sidewalls of the
light guide 110 that may produce a secondary reflection of the
guided light beams 112. Reflection from various spurious reflection
sources within the static multiview display 100 may be mitigated by
any of a number of methods including, but not limited to absorption
and controlled redirection of the spurious reflection.
[0070] FIG. 5A illustrates a plan view of a static multiview
display 100 including spurious reflection mitigation in an example,
according to an embodiment consistent with the principles described
herein. FIG. 5B illustrates a plan view of a static multiview
display 100 including spurious reflection mitigation in an example,
according to another embodiment consistent with the principles
described herein. In particular, FIGS. 5A and 5B illustrate the
static multiview display 100 comprising the light guide 110, the
light source 120, and the plurality of diffraction gratings 130.
Also illustrated is the plurality of guided light beams 112 with at
least one guided light beam 112 of the plurality being incident on
a sidewall 114a, 114b of the light guide 110. A potential spurious
reflection of the guided light beam 112 by the sidewalls 114a, 114b
is illustrated by a dashed arrow representing a reflected guided
light beam 112'.
[0071] In FIG. 5A, the static multiview display 100 further
comprises an absorbing layer 119 at the sidewalls 114a, 114b of the
light guide 110. The absorbing layer 119 is configured to absorb
incident light from the guided light beams 112. The absorbing layer
may comprise substantially any optical absorber including, but not
limited to, black paint applied to the sidewalls 114a, 114b for
example. As illustrated in 5A, the absorbing layer 119 is applied
to the sidewall 114b, while the sidewall 114a lacks the absorbing
layer 119, by way of example and not limitation. The absorbing
layer 119 intercepts and absorbs the incident guided light beam 112
effectively preventing or mitigating the production of the
potential spurious reflection from sidewall 114b. On the other
hand, guided light beam 112 incident on the sidewall 114a reflects
resulting in the production of the reflected guided light beam
112', illustrated by way of example and not limitation.
[0072] FIG. 5B illustrates spurious reflection mitigation using
controlled reflection angle. In particular, the light guide 110 of
the static multiview display 100 illustrated in FIG. 5B comprises
slanted sidewalls 114a, 114b. The slanted sidewalls have a slant
angle configured to preferentially direct the reflected guided
light beam 112' substantially away from the diffraction gratings
130. As such, the reflected guided light beam 112' is not
diffractively coupled out of the light guide 110 as an unintended
directional light beam. The slant angle of the sidewalls 114a, 114b
may be in the x-y plane, as illustrated. In other examples (not
illustrated), the slant angle of the sidewalls 114a, 114b may be in
another plane, e.g., the x-z plane to direct the reflected guided
light beam 112' out a top or bottom surface of the light guide 110.
Note that FIG. 5B illustrates sidewalls 114a, 114b that include a
slant along only a portion of thereof, by way of example and not
limitation.
[0073] According to some embodiment, the static multiview display
100 may comprise a plurality of light sources 120 that are
laterally offset from one another. The lateral offset of light
sources 120 of the light source plurality may provide a difference
in the radial directions of various guided light beams 102 at or
between individual diffraction gratings 130. The difference, in
turn, may facilitate providing animation of a displayed multiview
image, according to some embodiments. Thus, the static multiview
display 100 may be a quasi-static multiview display 100, in some
embodiments.
[0074] FIG. 6A illustrates a plan view of a static multiview
display 100 in an example, according to an embodiment consistent
with the principles described herein. FIG. 6B illustrates a plan
view of the static multiview display 100 of FIG. 6A in another
example, according to an embodiment consistent with the principles
described herein. The static multiview display 100 illustrated in
FIGS. 6A and 6B comprises a light guide 110 with a plurality of
diffraction gratings 130. In addition, the static multiview display
100 further comprises a plurality of light sources 120 that are
laterally offset from each other and configured to separately
provide guided light beams 112 having different radial directions
118 from one another, as illustrated.
[0075] In particular, FIGS. 6A and 6B illustrate a first light
source 120a at a first input location 116a and a second light
source 120b at a second input location 116b on the side 114 of the
light guide 110. The first and second input locations 116a, 116b
are laterally offset or shifted from one another along the side 114
(i.e., in an x-direction) to provide the lateral offset of
respective first and second light sources 120a, 120b. Additionally,
each of the first and second light sources 120a, 120b of the
plurality of light sources 120 provide a different plurality of
guided light beams 112 having respective different radial
directions from one another. For example, the first light source
120a may provide a first plurality of guided light beams 112a
having a first set of different radial directions 118a and the
second light source 120b may provide a second plurality of guided
light beams 112b having a second set of different radial directions
118b, as illustrated in FIGS. 6A and 6B, respectively. Further, the
first and second pluralities of guided light beams 112a, 112b
generally have sets of different radial directions 118a, 118b that
also differ from one another as sets by virtue of the lateral
offset of the first and second light sources 120a, 120b, as
illustrated.
[0076] Thus, the plurality of diffraction gratings 130 emit
directional light beams representing different multiview images
that are shifted in a view space from one another (e.g., angularly
shifted in view space). Thus, by switching between the first and
second light sources 120a, 120b, the static multiview display 100
may provide `animation` of the multiview images, such as a
time-sequenced animation. In particular, by sequentially
illuminating the first and second light sources 120a, 120b during
different sequential time intervals or periods, static multiview
display 100 may be configured to shift an apparent location of the
multiview image during the different time periods, for example.
This shift in apparent location provided by the animation may
represent and example of operating the static multiview display 100
as a quasi-static multiview display 100 to provide a plurality of
multiview image states, according to some embodiments.
[0077] According to various embodiments, as described above with
respect to FIGS. 3A-3C, the directional light beams 102 of the
static multiview display 100 are emitted using diffraction (e.g.,
by diffractive scattering or diffractive coupling). In some
embodiments, the plurality of the diffraction gratings 130 may be
organized as multiview pixels, each multiview pixel including a set
of diffraction gratings 130 comprising one or more diffraction
gratings 130 from the diffraction grating plurality. Further, as
has been discussed above, the diffraction grating(s) 130 have
diffraction characteristics that are a function of radial location
on the light guide 110 as well as being a function of an intensity
and direction of the directional light beams 102 emitted by the
diffraction grating(s) 130.
[0078] FIG. 7A illustrates a plan view of a diffraction grating 130
of a multiview display in an example, according to an embodiment
consistent with the principles described herein. FIG. 7B
illustrates a plan view of a set of diffraction gratings 130
organized as a multiview pixel 140 in an example, according to
another embodiment consistent with the principles described herein.
As illustrated in FIGS. 7A and 7B, each of the diffraction gratings
130 comprises a plurality of diffractive features spaced apart from
one another according to a diffractive feature spacing (which is
sometimes referred to as a `grating spacing`) or grating pitch. The
diffractive feature spacing or grating pitch is configured to
provide diffractive coupling out or scattering of the guided light
portion from within the light guide. In FIGS. 7A-7B, the
diffraction gratings 130 are on a surface of a light guide 110 of
the multiview display (e.g., the static multiview display 100
illustrated in FIGS. 3A-3C).
[0079] According to various embodiments, the spacing or grating
pitch of the diffractive features in the diffraction grating 130
may be sub-wavelength (i.e., less than a wavelength of the guided
light beams 112). Note that, while FIGS. 7A and 7B illustrate the
diffraction gratings 130 having a single or uniform grating spacing
(i.e., a constant grating pitch), for simplicity of illustration.
In various embodiments, as described below, the diffraction grating
130 may include a plurality of different grating spacings (e.g.,
two or more grating spacings) or a variable diffractive feature
spacing or grating pitch to provide the directional light beams
102, e.g., as is variously illustrated in FIGS. 3A-6B.
Consequently, FIGS. 7A and 7B are not intended to imply that a
single grating pitch is an exclusive embodiment of diffraction
grating 130.
[0080] According to some embodiments, the diffractive features of
the diffraction grating 130 may comprise one or both of grooves and
ridges that are spaced apart from one another. The grooves or the
ridges may comprise a material of the light guide 110, e.g., the
groove or ridges may be formed in a surface of the light guide 110.
In another example, the grooves or the ridges may be formed from a
material other than the light guide material, e.g., a film or a
layer of another material on a surface of the light guide 110.
[0081] As discussed previously and shown in FIG. 7A, the
configuration of the diffraction features comprises a grating
characteristic of the diffraction grating 130. For example, a
grating depth of the diffraction grating may be configured to
determine the intensity of the directional light beams 102 provided
by the diffraction grating 130. Alternatively or additionally,
discussed previously and shown in FIGS. 7A-7B, the grating
characteristic comprises one or both of a grating pitch of the
diffraction grating 130 and a grating orientation (e.g., the
grating orientation y illustrated in FIG. 7A). In conjunction with
the angle of incidence of the guided light beams, these grating
characteristics determine the principal angular direction of the
directional light beams 102 provided by the diffraction grating
130.
[0082] In some embodiments (not illustrated), the diffraction
grating 130 configured to provide the directional light beams
comprises a variable or chirped diffraction grating as a grating
characteristic. By definition, the `chirped` diffraction grating is
a diffraction grating exhibiting or having a diffraction spacing of
the diffractive features (i.e., the grating pitch) that varies
across an extent or length of the chirped diffraction grating. In
some embodiments, the chirped diffraction grating may have or
exhibit a chirp of the diffractive feature spacing that varies
linearly with distance. As such, the chirped diffraction grating is
a `linearly chirped` diffraction grating, by definition. In other
embodiments, the chirped diffraction grating of the multiview pixel
may exhibit a non-linear chirp of the diffractive feature spacing.
Various non-linear chirps may be used including, but not limited
to, an exponential chirp, a logarithmic chirp or a chirp that
varies in another, substantially non-uniform or random but still
monotonic manner. Non-monotonic chirps such as, but not limited to,
a sinusoidal chirp or a triangle or sawtooth chirp, may also be
employed. Combinations of any of these types of chirps may also be
employed.
[0083] In other embodiments, diffraction grating 130 configured to
provide the directional light beams 102 is or comprises a plurality
of diffraction gratings (e.g., sub-gratings). For example, the
plurality of diffraction gratings of the diffraction grating 130
may comprise a first diffraction grating configured to provide a
red portion of the directional light beams 102. Further, the
plurality of diffraction gratings of the diffraction grating 130
may comprise a second diffraction grating configured to provide a
green portion of the directional light beams 102. Further still,
the plurality of diffraction gratings of the diffraction grating
130 may comprise a third diffraction grating configured to provide
a blue portion of the directional light beams 102. In some
embodiments, individual diffraction gratings of the plurality of
diffraction gratings may be superimposed on one another. In other
embodiments, the diffraction gratings may be separate diffraction
gratings arranged next to one another, e.g., as an array.
[0084] More generally, the static multiview display 100 may
comprise one or more instances of multiview pixels 140, which each
comprise sets of diffraction gratings 130 from the plurality of
diffraction gratings 130. As shown in FIG. 7B, the diffraction
gratings 130 of the set that makes up a multiview pixel 140 may
have different grating characteristics. The diffraction gratings
130 of the multiview pixel may have different grating orientations,
for example. In particular, the diffraction gratings 130 of the
multiview pixel 140 may have different grating characteristics
determined or dictated by a corresponding set of views of a
multiview image. For example, the multiview pixel 140 may include a
set of eight (8) diffraction gratings 130 that, in turn, correspond
to 8 different views of the static multiview display 100. Moreover,
the static multiview display 100 may include multiple multiview
pixels 140. For example, there may be a plurality of multiview
pixels 140 with sets of diffraction gratings 130, each multiview
pixels 140 corresponding to a different one of 2048.times.1024
pixels in each of the 8 different views.
[0085] In some embodiments, static multiview display 100 may be
transparent or substantially transparent. In particular, the light
guide 110 and the spaced apart plurality of diffraction gratings
130 may allow light to pass through the light guide 110 in a
direction that is orthogonal to both the first surface 110' and the
second surface 110'', in some embodiments. Thus, the light guide
110 and more generally the static multiview display 100 may be
transparent to light propagating in the direction orthogonal to the
general propagation direction 103 of the guided light beams 112 of
the guided light beam plurality. Further, the transparency may be
facilitated, at least in part, by the substantially transparency of
the diffraction gratings 130.
[0086] In accordance with some embodiments of the principles
described herein, a multiview display is provided. The multiview
display is configured to emit a plurality of directional light
beams provided by the multiview display. Further, the emitted
directional light beams may be preferentially directed toward a
plurality of views zones of the multiview display based on the
grating characteristics of a plurality of diffraction grating that
are included in one or more multiview pixels in the multiview
display. Moreover, the diffraction gratings may produce different
principal angular directions in the directional light beams, which
corresponding to different viewing directions for different views
in a set of views of the multiview image of the multiview display.
In some examples, the multiview display is configured to provide or
`display` a 3D or multiview image. Different ones of the
directional light beams may correspond to individual view pixels of
different `views` associated with the multiview image, according to
various examples. The different views may provide a `glasses free`
(e.g., autostereoscopic) representation of information in the
multiview image being displayed by the multiview display, for
example.
[0087] FIG. 8 illustrates a block diagram of a static multiview
display 200 in an example, according to an embodiment consistent
with the principles described herein. According to various
embodiments, the static multiview display 200 is configured to
display a multiview image according to different views in different
view directions. In particular, a plurality of directional light
beams 202 emitted by the static multiview display 200 are used to
display the multiview image and may correspond to pixels of the
different views (i.e., view pixels). The directional light beams
202 are illustrated as arrows emanating from one or more multiview
pixels 210 in FIG. 8. Also illustrated in FIG. 8 are a first view
14', a second view 14'', and a third view 14''', of a multiview
image 16 that may be provided by the static multiview display
200.
[0088] Note that the directional light beams 202 associated with
one of multiview pixels 210 are either static or quasi-static
(i.e., not actively modulated). Instead, the multiview pixels 210
either provide the directional light beams 202 when they are
illuminated or do not provide the directional light beams 202 when
they are not illuminated. Further, an intensity of the provided
directional light beams 202 along with a direction of those
directional light beams 202 defines the pixels of the multiview
image 16 being displayed by the static multiview display 200,
according to various embodiments. Further, the displayed views 14',
14'', 14''' within the multiview image 16 are static or
quasi-static, according to various embodiments.
[0089] The static multiview display 200 illustrated in FIG. 8
comprises an array of the multiview pixels 210. The multiview
pixels 210 of the array are configured to provide a plurality of
different views of the static multiview display 200. According to
various embodiments, a multiview pixel 210 of the array comprises a
plurality of diffraction gratings 212 configured to diffractively
couple out or emit the plurality of directional light beams 202.
The plurality of directional light beams 202 may have principal
angular directions, which correspond to different views directions
of different views in a set of views of the static multiview
display 200. Moreover, grating characteristics of the diffraction
gratings 212 may be varied or selected based on the radial
direction of incident light beams to diffraction gratings 212, a
distance to a light source that provides the incident light beams
or both. In some embodiments, the diffraction gratings 212 and
multiview pixels 210 may be substantially similar to diffraction
gratings 130 and multiview pixel 140, respectively, of the static
multiview display 100, described above.
[0090] As illustrated in FIG. 8, the static multiview display 200
further comprises a light guide 220 configured to guide light. In
some embodiments, the light guide 220 may be substantially similar
to the light guide 110 described above with respect to the static
multiview display 100. According to various embodiments, the
multiview pixels 210, or more particularly the diffraction gratings
212 of the various multiview pixels 210, are configured to scatter
or couple out a portion of guided light (or equivalently `guided
light beams 204`, as illustrated) from the light guide 220 as the
plurality of directional light beams 202 (i.e., the guided light
may be the incident light beams discussed above). In particular,
the multiview pixels 210 are optically connected to the light guide
220 to scatter or couple out the portion of the guided light (i.e.,
guided light beams 204) by diffractive scattering or diffractive
coupling.
[0091] In various embodiments, grating characteristics of the
diffraction gratings 212 are varied based on or as a function of a
radial direction of incident guided light beams 204 at the
diffraction gratings 212, a distance between a light source that
provides the guided light beams 204, or both. In this way, the
directional light beams 202 from different diffraction gratings 212
in a multiview pixel may correspond to pixels of views of a
multiview image provided by the static multiview display 200.
[0092] The static multiview display 200 illustrated in FIG. 8
further comprises a light source 230. The light source 230 may be
configured to provide the light to the light guide 220. In
particular, the provided light (e.g., illustrated by arrows
emanating from the light source 230 in FIG. 8) is guided by the
light guide 220 as a plurality of guided light beams 204. The
guided light beams 204 of the guided light beam plurality have
different radial directions from one another within the light guide
220, according to various embodiments. In some embodiments, the
guided light beams 204 are provided with a non-zero propagation
angle and, in some embodiments, have a collimation factor to
provide a predetermined angular spread of the guided light beams
204 within the light guide 220, for example. According to some
embodiments, the light source 230 may be substantially similar to
one of the light source(s) 120 of the static multiview display 100,
described above. For example, the light source 230 may be
butt-coupled to an input edge of the light guide 220. The light
source 230 may radiate light in a fan-shape or radial pattern to
provide the plurality of guided light beams 204 having the
different radial directions.
[0093] In accordance with other embodiments of the principles
described herein, a method of static multiview display operation is
provided. FIG. 9 illustrates a flow chart of a method 300 of static
multiview display operation in an example, according to an
embodiment consistent with the principles described herein. The
method 300 of static multiview display operation may be used to
provide one or both display of a static multiview image and display
of a quasi-static multiview image, according to various
embodiments.
[0094] As illustrated in FIG. 9, the method 300 of static multiview
display operation comprises guiding 310 the light along the light
guide as a plurality of guided light beams having a common point of
origin and different radial directions from one another. In
particular, a guided light beam of the guided light beam plurality
has, by definition, a different radial direction of propagation
from another guided light beam of the guided light beam plurality.
Further, each of the guided light beams of the guided light beam
plurality has, by definition, a common point of origin. The point
of origin may be a virtual point of origin (e.g., a point beyond an
actual point of origin of the guided light beam), in some
embodiments. For example, the point of origin may be outside of the
light guide and thus be a virtual point of origin. According to
some embodiments, the light guide along which the light is guided
310 as well as the guided light beams that are guided therein may
be substantially similar to the light guide 110 and guided light
beams 112, respectively, as described above with reference to the
static multiview display 100.
[0095] The method 300 of static multiview display operation
illustrated in FIG. 9 further comprises emitting 320 a plurality of
directional light beams representing a multiview image using a
plurality of diffraction gratings. According to various
embodiments, a diffraction grating of the diffraction grating
plurality diffractively couples or scatters out light from the
guided light beam plurality as a directional light beam of the
directional light beam plurality. Further, the directional light
beam that is coupled or scattered out has both an intensity and a
principal angular direction of a corresponding view pixel of the
multiview image. In particular, the plurality of directional light
beams produced by the emitting 320 may have principal angular
directions corresponding to different view pixels in a set of views
of the multiview image. Moreover, intensities of directional light
beams of the directional light beam plurality may correspond to
intensities of various view pixels of the multiview image. In some
embodiments, each of the diffraction gratings produces a single
directional light beam in a single principal angular direction and
having a single intensity corresponding to a particular view pixel
in one view of the multiview image. In some embodiments, the
diffraction grating comprises a plurality of diffraction grating
(e.g., sub-gratings). Further, a set of diffraction gratings may be
arranged as a multiview pixel of the static multiview display, in
some embodiments.
[0096] In various embodiments, the intensity and principal angular
direction of the emitted 320 directional light beams are controlled
by a grating characteristic of the diffraction grating that is
based on (i.e., is a function of) a location of the diffraction
grating relative to the common origin point. In particular, grating
characteristics of the plurality of diffraction gratings may be
varied based on, or equivalently may be a function of, radial
directions of incident guided light beams at the diffraction
gratings, a distance from the diffraction gratings to a light
source that provides the guided light beams, or both.
[0097] According to some embodiments, the plurality of diffraction
gratings may be substantially similar to the plurality of
diffraction gratings 130 of the static multiview display 100,
described above. Further, in some embodiments, the emitted 320
plurality of directional light beams may be substantially similar
to the plurality of directional light beams 102, also described
above. For example, the grating characteristic controlling the
principal angular direction may comprise one or both of a grating
pitch and a grating orientation of the diffraction grating.
Further, an intensity of the directional light beam provided by the
diffraction grating and corresponding to an intensity of a
corresponding view pixel may be determined by a diffractive
coupling efficiency of the diffraction grating. That is, the
grating characteristic controlling the intensity may comprise a
grating depth of the diffraction grating, a size of the gratings,
etc., in some examples.
[0098] As illustrated, the method 300 of static multiview display
operation further comprises providing 330 light to be guided as the
plurality of guided light beams using a light source. In
particular, light is provided to the light guide as the guided
light beams having a plurality of different radial directions of
propagation using the light source. According to various
embodiments, the light source used in providing 330 light is
located at a side of the light guide, the light source location
being the common origin point of the guided light beam plurality.
In some embodiments, the light source may be substantially similar
to the light source(s) 120 of the static multiview display 100,
described above. In particular, the light source may be
butt-coupled to an edge or side of the light guide. Further, the
light source may approximate a point source representing the common
point of origin, in some embodiments.
[0099] In some embodiments (not illustrated), the method of static
multiview display operation further comprises animating the
multiview image by guiding a first plurality of light guided light
beams during a first time period and guiding a second plurality of
guided light beams during a second time period during a second
period. The first guided light beam plurality may have a common
origin point that differs from a common origin point of the second
guided light beam plurality. For example, the light source may
comprise a plurality of laterally offset light sources, e.g.,
configured to provide animation, as described above. Animation may
comprise a shift in an apparent location of the multiview image
during the first and second time periods, according to some
embodiments.
[0100] In some embodiments, the provided 330 light is substantially
uncollimated. In other embodiments, the provided 330 light may be
collimated (e.g., the light source may comprise a collimator). In
various embodiments, the provided 330 light may be the guided
having the different radial directions at a non-zero propagation
angle within the light guide between surfaces of the light guide.
When collimated within the light guide, the provided 330 light may
be collimated according to a collimation factor to establish a
predetermined angular spread of the guided light within the light
guide.
[0101] Thus, there have been described examples and embodiments of
a static multiview display and a method of static multiview display
operation having diffraction gratings configured to provide a
plurality of directional light beams representing a static or
quasi-static multiview image from guided light beams having
different radial directions from one another. It should be
understood that the above-described examples are merely
illustrative of some of the many specific examples that represent
the principles described herein. Clearly, those skilled in the art
can readily devise numerous other arrangements without departing
from the scope as defined by the following claims.
* * * * *