U.S. patent application number 13/947542 was filed with the patent office on 2014-01-23 for transparent diffuser for lighting and methods of manufacturing transparent diffuser.
This patent application is currently assigned to PANASONIC CORPORATION. The applicant listed for this patent is PANASONIC CORPORATION. Invention is credited to Yosuke MIZUYAMA.
Application Number | 20140023319 13/947542 |
Document ID | / |
Family ID | 49946611 |
Filed Date | 2014-01-23 |
United States Patent
Application |
20140023319 |
Kind Code |
A1 |
MIZUYAMA; Yosuke |
January 23, 2014 |
TRANSPARENT DIFFUSER FOR LIGHTING AND METHODS OF MANUFACTURING
TRANSPARENT DIFFUSER
Abstract
A light diffuser panel for coupling to an optical element,
includes a substrate with a first surface that is diffusive to a
plurality of wavelengths of light and a second surface, wherein the
substrate comprises a material with a refractive index n.sub.in
that is greater than a refractive index n.sub.d of a medium outside
of the first surface, .lamda..sub.min is a minimum wavelength of
the plurality of wavelengths of light, .lamda..sub.max is a maximum
wavelength of the plurality of wavelengths of light, the first
surface is a diffractive grating surface with a grating period P,
the grating period P is greater than
.lamda..sub.max/(n.sub.d+n.sub.in), and P is smaller than
.lamda..sub.min.
Inventors: |
MIZUYAMA; Yosuke; (Newton,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PANASONIC CORPORATION |
Osaka |
|
JP |
|
|
Assignee: |
PANASONIC CORPORATION
Osaka
JP
|
Family ID: |
49946611 |
Appl. No.: |
13/947542 |
Filed: |
July 22, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13553925 |
Jul 20, 2012 |
|
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13947542 |
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Current U.S.
Class: |
385/37 ;
264/1.24 |
Current CPC
Class: |
G02B 6/0051 20130101;
G02B 6/34 20130101; G02B 6/0038 20130101; G02B 5/0252 20130101;
B29D 11/00798 20130101; B29D 11/00721 20130101 |
Class at
Publication: |
385/37 ;
264/1.24 |
International
Class: |
G02B 6/34 20060101
G02B006/34; B29D 11/00 20060101 B29D011/00 |
Claims
1. A light diffuser panel for coupling to an optical element,
comprising: a substrate with a first surface that is diffusive to a
plurality of wavelengths of light and a second surface; wherein the
substrate comprises a material with a refractive index n.sub.in
that is greater than a refractive index n.sub.d of a medium outside
of the first surface, .lamda..sub.min is a minimum wavelength of
the plurality of wavelengths of light, .lamda..sub.max is a maximum
wavelength of the plurality of wavelengths of light, the first
surface is a diffractive grating surface with a grating period P,
the grating period P is greater than
.lamda..sub.max/(n.sub.d+n.sub.in), and P is smaller than
.lamda..sub.min.
2. The light diffuser panel according to claim 1, wherein the
substrate comprises at least one location on an edge of the
substrate configured to receive the plurality of wavelengths of
light from a light emitting element, at an angle of incidence
relative to a normal of one of the first surface and the second
surface, the angle of incidence being greater than a critical angle
of the substrate, such that the plurality of wavelengths of light
are waveguided in the substrate by total internal reflection and
diffused by diffraction to allow a portion of at least one of the
plurality of wavelengths of light to exit the substrate from at
least one of the first surface and the second surface.
3. The light diffuser panel according to claim 2, wherein the light
emitting element is mounted on the at least one location on the
edge of the substrate, coupled to the substrate and configured to
transmit the plurality of wavelengths of light into the substrate
at the angle of incidence.
4. The light diffuser panel according to claim 1, wherein the first
surface comprises a plurality of binary grating grooves to allow a
portion of at least one of the plurality of wavelengths of light to
exit the substrate from the first surface and the second
surface.
5. The light diffuser panel according to claim 1, wherein the first
surface comprises a plurality of blaze grating grooves to allow a
portion of at least one of the plurality of wavelengths of light to
exit the substrate from only the second surface.
6. The light diffuser panel according to claim 1, wherein the first
surface comprises at least one of symmetrical triangular grating,
symmetrical sinusoidal grating, asymmetrical triangular grating,
and asymmetrical sinusoidal grating.
7. The light diffuser panel according to claim 2, wherein the light
emitting element comprises at least one of a LED, a laser diode, a
fluorescent light source, an optical waveguide, an optical
reflector, an optical refractor, and a polarizer.
8. The light diffuser panel according to claim 1, wherein the first
surface comprises a plurality of grating grooves in a pattern
comprising at least one of parallel grooves, diagonal grooves,
triangular grooves, spiral grooves, and hatched grooves.
9. A manufacturing process for manufacturing a light diffuser panel
that is capable of diffusing a plurality of wavelengths of light,
wherein .lamda..sub.min is a minimum wavelength of the plurality of
wavelengths of light and .lamda..sub.max is a maximum wavelength of
the plurality of wavelengths of light, the method comprising:
determining a material for a substrate with a refractive index
n.sub.in that is greater than a refractive index n.sub.d of a
medium within which the substrate is positioned; selecting a
grating period P, wherein the grating period P is greater than
.lamda..sub.max/(n.sub.d+n.sub.in), and P is smaller than
.lamda..sub.min; and forming the substrate with a first surface
that is diffusive to the plurality of wavelengths of light and a
second surface, wherein the first surface is a diffractive grating
surface with a grating period P.
10. The manufacturing process for manufacturing a light diffuser
panel according to claim 9, wherein forming the substrate
comprises: forming a mold with a molding surface that is an inverse
match of the first surface having the diffractive grating surface
with the grating period P; and at least one of injecting and
casting the material into the mold to form the substrate.
11. The manufacturing process for manufacturing a light diffuser
panel according to claim 9, wherein forming the substrate
comprises: forming the substrate; and at least one of cutting,
etching, and pressing the first surface to form the diffractive
grating surface on the first surface.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation application of pending U.S. patent
application Ser. No. 13/553,925, filed Jul. 20, 2012. The
disclosures of these documents, including the specifications,
drawings and claims, are incorporated herein by reference in their
entirety.
BACKGROUND
[0002] 1. Field of the Disclosure
[0003] The present invention generally relates to light diffusers
for illuminating environments or objects and methods of
manufacturing light diffusers.
[0004] 2. Background Information
[0005] Light sources used for illumination typically require
diffusers to diffuse or to spread out or to scatter the light to
produce soft light, which generally cast shadows with no edges or
soft edges as opposed to sharp edges. For example, in photography,
soft light is used to reduce visibility of wrinkles for people to
achieve a more youthful look.
[0006] Typical diffusers are hazy in appearance, or the diffusers
are opaque or non-transparent. That is, an observer cannot see
objects clearly through a typical diffuser. Typical diffusers may
include for example, ground glass diffusers, teflon diffusers,
holographic diffusers, opal glass diffusers, and greyed glass
diffusers. Because such diffusers are not transparent, their
presence in the view of observers may seem distracting and
unpleasant. Additionally, typical diffusers may scatter significant
amount of light back toward the light source, and thus, efficiency
of the light source is reduced when such typical diffusers are
used.
[0007] FIG. 1 illustrates a conventional diffuser panel, which may
be for example, a ground glass diffuser panel.
[0008] Such conventional ground glass diffuser panels are
isotropically diffusive and therefore look hazy and not
transparent. As illustrated in FIG. 1, when light, generally with
wavelength in the visible band, intersects the diffusive surface 12
of the diffuser panel 10, the uneven and rough texture of the
diffusive surface causes the light to become scattered or diffused
in nearly all directions, depending on the varying surface angles
of the diffusive surface. The diffuser panel 10 comprises another
surface 14, which may be generally flat or can be another diffusive
surface. Because the light is diffused in nearly all directions,
the diffuser is called isotropically diffusive. Furthermore,
because the diffuser is isotropically diffusive, regardless of the
angle of the incident light intersecting the diffusive surface,
normal incident light, which is light intersecting generally
perpendicularly to the plane of diffuser (.theta..sub.in=0), would
also be diffused isotropically. This would thus cause objects to
appear hazy and not clearly visible when viewed through such
conventional ground glass diffusers, thus making the conventional
ground glass diffusers appear opaque or non-transparent.
[0009] FIG. 2 illustrates another conventional diffuser panel,
which may be for example, an ordinary grating type diffuser panel
with a grating period (not shown) greater than the wavelengths of
visible light.
[0010] Such conventional ordinary grating diffuser panels are also
isotropically diffusive and therefore look hazy and not
transparent. As illustrated in FIG. 2, light intersects the
diffusive surface 22 of the diffuser panel 20. The diffusive
surface 22 has a grating period (not shown). The grating period is
the distance between the corresponding edges of adjacent grooves of
the grating. The grating period (not shown) of such a conventional
ordinary grating diffuser panel is greater than the wavelengths of
visible light. The grating of the diffusive surface 22 causes the
light to become scattered or diffused in nearly all directions. The
diffuser is therefore also isotropically diffusive. This causes the
grating surface to appear non-transparent. The diffuser panel 20
has another surface 24, which may be generally flat. Furthermore,
because the diffuser is generally isotropically diffusive
regardless of the angle of the incident light intersecting the
diffusive surface, normal incident light (.theta..sub.in=0) would
also be diffused isotropically. This would thus cause objects to
appear hazy and not clearly visible when viewed through such
conventional ordinary grating diffusers, thus making the
conventional ordinary grating diffusers appear opaque or
non-transparent.
[0011] FIG. 3 illustrates a conventional subwavelength
anti-reflective (AR) surface panel with a binary grating, which
looks transparent but does not defuse light.
[0012] As illustrated in FIG. 3, the conventional subwavelength
binary grating panel 30 has a surface 32 with grating period P1 and
another surface 34 which may be generally flat.
[0013] The grating equation showing the relationship between the
grating period p, refractive index of incident side n.sub.in,
refractive index of exit side n.sub.d, incident angle
.theta..sub.in, diffraction angle .theta..sub.d, incident light
wavelength .lamda., and diffraction order in (integer) is given
by,
p(n.sub.d sin .theta..sub.d-n.sub.in sin .theta..sub.in)=m.lamda.
(1)
[0014] The conventional subwavelength AR binary grating surfaces
may satisfy,
where the grating period p=P1, and P1<.lamda.(n.sub.d+n.sub.in)
(2)
[0015] When equation (2) is true, then there is no solution for
equation (1) for diffraction orders (where 1 ml is greater or equal
to 1, and |sin .theta..sub.in|.ltoreq.1), and only zero order
diffraction occurs for all incident angles.
[0016] For example, if n.sub.d=1 (air), n.sub.in=1.5 (acrylic),
then if the grating period P1<.lamda./2.5, the panel will not
diffract light of .lamda.. If .lamda.=0.39 um (the low wavelength
end of the visible spectrum), then if P1<0.156 um, P1 would be
less than .lamda./2.5 for all the higher wavelengths of the visible
spectrum as well, and the panel will not diffract any visible
light.
[0017] In such a case, there is no diffraction of light, such that
the light can transmit through the panel without being diffracted.
This would cause objects to be clearly visible when viewed through
such conventional subwavelength binary grating from any angle, thus
making the conventional subwavelength binary grating appear
transparent. Because there is also little to no reflection of light
in the conventional subwavelength binary grating, the conventional
subwavelength binary grating would also appear to be
anti-reflective.
[0018] Therefore, a transparent diffuser that can provide higher
efficiency of lighting and a more pleasant transparent view may be
needed.
SUMMARY OF THE DISCLOSURE
[0019] The present disclosure, through one or more of its various
aspects, embodiments, and/or specific features or sub-components,
provides various device, apparatus, or structures that can achieve
the transparent diffuser, as well as method that can be used to
manufacture the transparent diffuser.
[0020] In one embodiment of the invention, a light diffuser panel
for coupling to an optical element, includes a substrate with a
first surface that is diffusive to a plurality of wavelengths of
light and a second surface, wherein the substrate comprises a
material with a refractive index n.sub.in that is greater than a
refractive index n.sub.d of a medium outside of the first surface,
.lamda..sub.min is a minimum wavelength of the plurality of
wavelengths of light, .lamda..sub.max is a maximum wavelength of
the plurality of wavelengths of light, the first surface is a
diffractive grating surface with a grating period P, the grating
period P is greater than .lamda..sub.max/(n.sub.d+n.sub.in), and P
is smaller than .lamda..sub.min.
[0021] According to another feature of the invention, the substrate
comprises at least one location on an edge of the substrate
configured to receive the plurality of wavelengths of light from a
light emitting element, at an angle of incidence relative to the
normal of one of the first surface and the second surface, the
angle of incidence being greater than a critical angle of the
substrate, such that the plurality of wavelengths of light are
waveguided in the substrate by total internal reflection and
diffused by diffraction to allow a portion of at least one of the
plurality of wavelengths of light to exit the substrate from at
least one of the first surface and the second surface.
[0022] According to another feature of the invention, the light
emitting element is mounted on the at least one location on the
edge of the substrate, coupled to the substrate and configured to
transmit the plurality of wavelengths of light into the substrate
at the angle of incidence.
[0023] According to another feature of the invention, the first
surface comprises a plurality of binary grating grooves to allow a
portion of at least one of the plurality of wavelengths of light to
exit the substrate from the first surface and the second
surface.
[0024] According to another feature of the invention, the first
surface comprises a plurality of blaze grating grooves to allow a
portion of at least one of the plurality of wavelengths of light to
exit the substrate from only the second surface.
[0025] According to another feature of the invention, the first
surface comprises at least one of symmetrical triangular grating,
symmetrical sinusoidal grating, asymmetrical triangular grating,
and asymmetrical sinusoidal grating.
[0026] According to another feature of the invention, the light
emitting element comprises at least one of a LED, a laser diode, a
fluorescent light source, an optical waveguide, an optical
reflector, an optical refractor, and a polarizer.
[0027] According to another feature of the invention, the first
surface comprises a plurality of grating grooves in a pattern
comprising at least one of parallel grooves, diagonal grooves,
triangular grooves, spiral grooves, and hatched grooves.
[0028] Another embodiment of the invention relates to a
manufacturing process or method for manufacturing a light diffuser
panel that is capable of diffusing a plurality of wavelengths of
light, wherein .lamda..sub.min is a minimum wavelength of the
plurality of wavelengths of light and .lamda..sub.max is a maximum
wavelength of the plurality of wavelengths of light. The method
includes determining a material for a substrate with a refractive
index n.sub.in that is greater than a refractive index n.sub.d of a
medium within which the substrate is positioned, selecting a
grating period P, wherein the grating period P is greater than
.lamda..sub.max/(n.sub.d+n.sub.in), and P is smaller than
.lamda..sub.min, and forming the substrate with a first surface
that is diffusive to the plurality of wavelengths of light and a
second surface, wherein the first surface is a diffractive grating
surface with a grating period P.
[0029] According to another feature of the invention, the forming
of the substrate includes forming a mold with a molding surface
that is an inverse match of the first surface having the
diffractive grating surface with the grating period P; and at least
one of injecting and casting the material into the mold to form the
substrate.
[0030] According to another feature of the invention, the forming
of the substrate includes forming the substrate; and at least one
of cutting, etching, and pressing the first surface to form the
diffractive grating surface on the first surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The present invention is further described in the detailed
description which follows, in reference to the noted plurality of
drawings, by way of non-limiting examples of preferred embodiments
of the present invention, in which like characters represent like
elements throughout the several views of the drawings.
[0032] FIG. 1 illustrates a conventional diffuser panel.
[0033] FIG. 2 illustrates another conventional diffuser panel.
[0034] FIG. 3 illustrates a conventional subwavelength
anti-reflective (AR) diffuser panel.
[0035] FIG. 4 illustrates a cross sectional view of an exemplary
binary grating surface panel in accordance with the embodiment
described herein.
[0036] FIG. 5 illustrates a cross sectional view of an exemplary
blaze grating surface panel in accordance with the embodiment
described herein.
[0037] FIG. 6A illustrates the optical reflection characteristics
of an exemplary binary grating surface panel, with imperfect total
internal reflection (TIR) in accordance with the embodiment
described herein.
[0038] FIG. 6B illustrates the optical reflection characteristics
of an exemplary blaze grating surface panel, with restored total
internal reflection (TIR) in accordance with the embodiment
described herein.
[0039] FIGS. 7A-7D illustrate exemplary diffuser panels with light
emitting elements integrated on one edge in plane views and cross
sectional views in accordance with the embodiment described
herein.
[0040] FIG. 8 illustrates an exemplary manufacturing process flow
for manufacturing the diffuser panels in accordance with the
embodiment described herein.
DETAILED DESCRIPTION
[0041] The present disclosure, through one or more of its various
aspects, embodiments and/or specific features or sub-components, is
thus intended to bring out one or more of the advantages as
specifically noted below.
[0042] FIG. 4 illustrates a cross sectional view of an exemplary
binary grating surface diffuser panel in accordance with the
embodiment described herein. The diffuser panel 100 is generally
shown in the cross sectional view. The diffuser panel 100 comprises
a grating surface 102 which may be, for example, a binary grating
surface. Also for example, the other surface 104 of the diffuser
panel 100 may be generally flat and smooth.
[0043] The exemplary binary grating surface 102 has a grating
period P2 that satisfies,
.lamda.(n.sub.d+n.sub.in)<P2<.lamda., (3)
[0044] (for coverage of the entire visible spectrum, .lamda. is
preferably from 0.38 um to 0.78 um).
[0045] Equation (1) yields no solution for the diffraction order
(non-zero m) for the normal incident angle (.theta..sub.in=0) or
near the normal incident angle, such that the light at or near the
normal incident angle transmits through the panel without being
diffracted. In such a case, objects would be clearly visible when
viewed through the exemplary binary grating surface diffuser panel,
through either panel sides of the diffuser panel at or near the
normal incident angle. Thus, the exemplary diffuser panel would
appear to be transparent.
[0046] On the other hand, for incident angles greater than the
total internal reflection angle (or the critical angle),
sin.sup.-1(1/n.sub.in), which are the angles for light waveguided
in the diffuser panel, equation (1) yields diffraction orders but
only a few (preferably only one). This diffraction is diffusive,
because the light is spread out and can be emitted over the entire
panel surface. The exemplary diffuser panel can be used for
illumination if light is waveguided in the panel and directed
toward the grating surface 102 at an oblique angle.
[0047] For an illustrative example:
[0048] If .lamda./p=1.5 and n.sub.d=1 (air), n.sub.in=1.5 (acrylic)
satisfying .lamda./(n.sub.d+n.sub.in)<p<.lamda., the grating
equation of equation (1) can rewritten as
sin .theta..sub.d=1.5m+1.5 sin .theta..sub.in (4)
[0049] In this case, diffraction angle .theta..sub.d would have no
solution for non-zero m, and only zero order diffractions occurs,
if |1.5 sin .theta..sub.in|<0.5, or
|.theta..sub.in|<19.47.degree.. Thus, objects would be clearly
visible when viewed at an angle |.theta..sub.in|<19.47.degree.,
where there are no diffraction orders.
[0050] The solutions to equation (1) for a waveguided light at an
incident angle .theta..sub.in=60.degree. in this example yield one
set of transmission diffraction order light rays (T-1.sup.st) at
generally -11.6.degree., reflection diffraction order light rays
(R-1.sup.st) at generally -11.6.degree. in the other side, and
reflection zero order light rays (R0.sup.th) at the waveguided
light angle of .theta..sub.m=60.degree..
[0051] As illustrated in FIG. 4, the transmission and reflection
diffraction orders light rays (T-1.sup.st) and (R-1.sup.st) are
transmitted out of the diffuser panel as illumination while the
reflection zero order light rays (R0.sup.th) continues to propagate
inside the panel as waveguided light to generate additional sets of
transmission and reflection diffraction orders light rays
(T-1.sup.st) and (R-1.sup.st) at the subsequent locations where the
reflection zero order light rays (R0.sup.th) intersects the grating
surface 102 of the panel.
[0052] Preferrably, the grating period P2 satisfies,
.lamda..sub.max/(n.sub.d+n.sub.in)<P2<.lamda..sub.min (5)
[0053] for multiple wavelengths ranging from a minimum wavelength
.lamda..sub.min and a maximum wavelength .lamda..sub.max (where
.lamda..sub.min<.lamda..sub.max).
[0054] For an illustrative example, if .lamda..sub.min=0.38 um
(minimum wavelength of visible light), .lamda..sub.max=0.78 um
(maximum wavelength of visible light), n.sub.d=1 (air) and
n.sub.in=1.5 (acrylic), the preferred range of p is 0.312
um<p<0.38 um.
[0055] FIG. 6A illustrates the optical reflection characteristics
of the above exemplary diffuser panel 100, in accordance with the
embodiment described herein. As illustrated in FIG. 4, a binary
grating surface such as the grating surface 102 disclosed in the
above embodiment allows for bi-directional illumination, which is
where the diffuser panel 100 cast diffused light from the
waveguided light at both sides of the panel. The bi-directional
illumination capability of the grating surface 102 is due to the
imperfect total internal reflection (TIR) in the case of the binary
grating surface. As illustrated in FIG. 6A, in the case of the
binary grating surface, imperfect TIR causes less than 100% of the
light to reflect at above the TIR angle (or the critical angle).
The light rays that are not reflected are leaked out as the
transmission diffraction orders light rays (T-1.sup.st) noted
above.
[0056] FIG. 5 illustrates a cross sectional view of another
exemplary diffuser panel in accordance with the embodiment
described herein. The diffuser panel 200 is generally shown in the
cross sectional view. The diffusive surface 202 is a grating
surface, for example, a blaze grating surface. Also for example,
the lower surface 204 may be generally flat and smooth.
[0057] The exemplary blaze grating surface 202 has a grating period
P3 that satisfies,
.lamda./(n.sub.d+n.sub.in)<P3<.lamda., (similar to equation 3
above)
[0058] which yields no solution for the diffraction order (non-zero
m) for the normal incident angle (.theta..sub.in=0) or near the
normal incident angle, such that the light at or near the normal
incident angle transmits through the panel without being
diffracted. In such a case, objects would be clearly visible when
viewed through the exemplary diffuser panel, through either side of
the diffuser panel at or near the normal incident angle. Thus, the
exemplary diffuser panel would appear transparent.
[0059] On the other hand, for incident angles greater than the
total internal reflection angle (or the critical angle), which are
the angles for light waveguided in the diffuser panel, equation (1)
yields diffraction orders but only a few (preferably only one).
This diffraction is diffusive, because the light is spread out and
can be cast out over the entire panel surface. The exemplary
diffuser panel can be used for illumination if light is waveguided
in the panel and directed toward the grating surface 202 at an
oblique angle.
[0060] Different from the diffuser panel 100 with binary grating
surface 102 illustrated in FIG. 4, the diffuser panel 200 with
blaze grating surface 202 illustrated in FIG. 5 has only one
reflection diffraction order of light rays (R-1.sup.st) and only
one order of diffraction. Thus, the waveguided light directed
toward the grating surface 202 at an oblique angle would cause
illumination on only one side of the diffuser panel 200,
specifically the side opposite the grating surface 202, or on the
same side as the lower surface 204.
[0061] The present invention describes exemplary diffuser panels
with a binary grating surface and a blaze grating surface. It is
understood that other types of grating surfaces, for example, a
sinusoidal grating surface, may also be used.
[0062] FIG. 6B illustrates the optical reflection characteristics
of the exemplary diffuser panel 200 illustrated in FIG. 5, in
accordance with the embodiment described herein. As disclosed
above, the diffuser panel 200 with blaze grating surface 202
illustrated in FIG. 5 has only one reflection diffraction order of
light rays (R-1.sup.st) and only one order of diffraction, causing
illumination from the waveguided light on only one side of the
diffuser panel 200. This uni-directional illumination is due to the
properties of blaze grating surface 202 illustrated in FIG. 6B,
which shows the total internal reflection (TIR) is restored to 100%
reflection above the TIR angle (or the critical angle), such that
there are no leakages of lights as transmission diffraction orders
light rays (T-1.sup.st) above the TIR angle (or the critical
angle).
[0063] FIGS. 7A-7D illustrate exemplary diffuser panels with light
emitting elements integrated on one edge in plane views and cross
sectional views in accordance with the embodiment described
herein.
[0064] FIG. 7A illustrates a plane view and a cross sectional view
of one exemplary diffuser panel with a similar cross sectional
profile as the diffuser panel illustrated in FIG. 4. The diffuser
panel 300 may have for example, a binary grating surface. The
diffuser panel 300 may be integrated with a light emitting element
350 on one edge of the diffuser panel 300. The light emitting
element 350 may be for example, light source such as LED, laser
diode and SLD (super luminescent diode), or coupling optics such as
collection lens, collimator, and beam shaper, etc. which transmit
light generated from a source of light. The light emitting element
350 may be mounted or bonded on the one edge of the diffuser panel
300, for example by mechanical mounting structures, chemical
adhesives, heating, or a combination of such mounting methods. The
light emitting element 350 may be for example, designed to direct
light of one or more visible wavelengths into the diffuser panel
300 from the one edge, at one or more oblique angles relative to
the plane of the diffuser panel 300, or at one or more angles that
are greater than the total internal reflection (TIR) angle or
critical angle of the diffuser panel 300.
[0065] In this configuration, the light transmitted by the light
emitting element 350 into the diffuser panel 300 will be waveguided
and diffused from generally the entire surface of diffuser panel
300, as noted above, to illuminate objects on both sides of the
panel via bi-directional illumination. As also noted above, the
illuminated objects would be clearly visible when viewed through
the panel. This provides a transparent diffuser that can provide
higher efficiency of lighting and a more pleasant transparent
view.
[0066] FIG. 7C illustrates a plane view and a cross sectional view
of another exemplary diffuser panel. The diffuser panel 500 is
integrated with a light emitting element 550, which may be similar
to the light emitting element 350 illustrated in FIG. 7A. The
diffuser panel 500 comprises a blaze grating surface as shown.
[0067] In this configuration, the light transmitted by the light
emitting element 550 into the diffuser panel 500 will be waveguided
and diffused from generally the entire surface of diffuser panel
500, as noted above, to illuminate objects. As also noted above,
the illuminated objects would be clearly visible when viewed
through the panel. This provides a transparent diffuser that can
provide higher efficiency of lighting and a more pleasant
transparent view.
[0068] FIGS. 7B and 7D illustrate plane views and cross sectional
views of two other exemplary diffuser panels. The diffuser panels
400 and 600 are similar to the diffuser panels 300 and 500 in FIGS.
7A and 7C, but the diffuser panels 400 and 600 may include for
example, additional grating grooves in diagonal patterns or
crisscrossing patterns. The additional grating grooves introduce
additional diffraction angles and patterns to the diffused light,
and thus provide more scattered illumination effect for the
diffuser panels 400 and 600.
[0069] The grating patterns as illustrated are intended as
non-limiting examples. Additional grating patterns are possible,
for example, spiral, arbitrary, triangular, curved, and etc.
[0070] The diffuser according to the present disclosed invention
can be made with ordinary diamond cutting on a molding material
(nickel for example) to form a mold, and then the diffuser panel is
formed by casting or injecting a substrate material, such as a
transparent plastic material, into the mold.
[0071] Alternatively, a different kind of mold can be made by
electron beam writing on electron beam resist spun on a silicon
wafer, the resist is developed and the silicon is etched using an
ordinary reactive ion etching machine. The silicon mold is mounted
in a step-and-repeat daughter mold generation machine to make a
larger size daughter mold. The diffuser panel is then formed by
casting or injecting a substrate material, such as a transparent
plastic material, into the daughter mold.
[0072] Further, a diffuser panel can be directly made by laser
cutting on a preformed transparent substrate panel using any kind
of laser such as CW or pulsed CO2 laser, DPSS (Diode Pumped Solid
State) laser, fiber laser, disc laser, laser diode, excimer laser,
femto-second laser, pico-second laser, and nano-second laser.
[0073] FIG. 8 illustrates an exemplary manufacturing process flow
for manufacturing the diffuser panels in accordance with the
embodiment described herein. The manufacturing process 800 starts
at step 810, where the appropriate substrate material and the
grating period for the diffuser panel are determined or selected.
The determination of the substrate material may depend upon
availability of material, cost of material and manufacturing,
quality and reliability of the material, and the type of use
intended for the diffuser panel. Once the substrate material is
selected, its refractive index may also be known. Then the grating
period p for the diffuser panel can be determined or chosen using
the equation:
.lamda..sub.max/(n.sub.d+n.sub.in)<p<.lamda..sub.min,
(similar to equation 5 above).
[0074] At step 815, if the process is done by molding the material
using a mold that comprises a grating surface, then the process
continues to step 820. Otherwise, a mold without a grating surface
would be used, then the process continues to step 840.
[0075] At step 820, a mold may be formed by pressing, cutting,
and/or etching processes, such as, diamond cutting, laser cutting,
chemical etching, ion etching, resist patterned etching, etc., to
make the molding surface for the grating surface of the diffuser
panel, using the determined grating period. Or intermediary molds
may be formed by such cutting and/or etching processes, and then
the molding surface for the grating surface can be transferred to a
final mold by pressing, or other transfer methods.
[0076] At step 830, the diffuser panel is formed by casting or
injection the substrate material into the final mold. The diffuser
panel would be then formed with the grating surface. Then the
diffuser panel may be separated and removed from the mold. Some
additional cutting, polishing, cleaning, baking, annealing,
setting, and/or laminating steps may be performed on the diffuser
panel to finalize its form and adjust its functions. Additionally,
light emitting elements may be mounted on the diffuser panel as an
integrating process step. After step 830, the diffuser panel is
completed, and the process ends.
[0077] Alternative to steps 820 and 830, at step 840, a transparent
panel substrate is preformed using the selected substrate material,
by for example, casting or injecting the material into a mold that
does not have a molding surface for the grating surface. Some
additional cutting, polishing, cleaning, baking, annealing,
setting, and/or laminating steps may be performed on the
transparent panel to adjust its form and its functions.
[0078] At step 850, the transparent panel substrate is pressed,
cut, and/or etched by processes, such as, diamond cutting, laser
cutting, chemical etching, ion etching, resist patterned etching,
etc., to form the grating surface of the diffuser panel, using the
determined grating period. Some additional cutting, polishing,
cleaning, baking, annealing, setting, and/or laminating steps may
be performed on the diffuser panel to finalize its form and adjust
its functions. Additionally, light emitting elements may be mounted
on the diffuser panel as an integrating process step. After step
850, the diffuser panel is completed, and the process ends.
[0079] Although the invention has been described with reference to
several exemplary embodiments, it is understood that the words that
have been used are words of description and illustration, rather
than words of limitation. Changes may be made within the purview of
the appended claims, as presently stated and as amended, without
departing from the scope and spirit of the invention in its
aspects. Although the invention has been described with reference
to particular means, materials and embodiments, the invention is
not intended to be limited to the particulars disclosed; rather the
invention extends to all functionally equivalent structures,
methods, and uses such as are within the scope of the appended
claims.
[0080] Although the present specification describes components and
functions that may be implemented in particular embodiments with
reference to particular standards and protocols, the disclosure is
not limited to such standards and protocols. Such standards are
periodically superseded by faster or more efficient equivalents
having essentially the same functions. Accordingly, replacement
standards and protocols having the same or similar functions are
considered equivalents thereof.
[0081] The illustrations of the embodiments described herein are
intended to provide a general understanding of the various
embodiments. The illustrations are not intended to serve as a
complete description of all of the elements and features of
apparatus and systems that utilize the structures or methods
described herein. In this regard, no attempt is made to show
structural details of the present invention in more detail than is
necessary for the fundamental understanding of the present
invention. Many other embodiments may be apparent to those of skill
in the art upon reviewing the disclosure. Other embodiments may be
utilized and derived from the disclosure, such that structural and
logical substitutions and changes may be made without departing
from the scope of the disclosure. Additionally, the illustrations
are merely representational and may not be drawn to scale. Certain
proportions within the illustrations may be exaggerated, while
other proportions may be minimized. Accordingly, the disclosure and
the figures are to be regarded as illustrative rather than
restrictive.
[0082] One or more embodiments of the disclosure may be referred to
herein, individually and/or collectively, by the term "invention"
merely for convenience and without intending to voluntarily limit
the scope of this application to any particular invention or
inventive concept. Moreover, although specific embodiments have
been illustrated and described herein, it should be appreciated
that any subsequent arrangement designed to achieve the same or
similar purpose may be substituted for the specific embodiments
shown. This disclosure is intended to cover any and all subsequent
adaptations or variations of various embodiments. Combinations of
the above embodiments, and other embodiments not specifically
described herein, will be apparent to those of skill in the art
upon reviewing the description.
[0083] The Abstract of the Disclosure is provided to comply with 37
C.F.R. .sctn.1.72(b) and is submitted with the understanding that
it will not be used to interpret or limit the scope or meaning of
the claims. In addition, in the foregoing Detailed Description,
various features may be grouped together or described in a single
embodiment for the purpose of streamlining the disclosure. This
disclosure is not to be interpreted as reflecting an intention that
the claimed embodiments require more features than are expressly
recited in each claim. Rather, as the following claims reflect,
inventive subject matter may be directed to less than all of the
features of any of the disclosed embodiments. Thus, the following
claims are incorporated into the Detailed Description, with each
claim standing on its own as defining separately claimed subject
matter.
[0084] The above disclosed subject matter is to be considered
illustrative, and not restrictive, and the appended claims are
intended to cover all such modifications, enhancements, and other
embodiments which fall within the true spirit and scope of the
present disclosure. Thus, to the maximum extent allowed by law, the
scope of the present disclosure is to be determined by the broadest
permissible interpretation of the following claims and their
equivalents, and shall not be restricted or limited by the
foregoing detailed description.
* * * * *