U.S. patent application number 11/436192 was filed with the patent office on 2006-09-21 for reflection-type video projection screen.
Invention is credited to Howard Sinkoff.
Application Number | 20060209405 11/436192 |
Document ID | / |
Family ID | 29214818 |
Filed Date | 2006-09-21 |
United States Patent
Application |
20060209405 |
Kind Code |
A1 |
Sinkoff; Howard |
September 21, 2006 |
Reflection-type video projection screen
Abstract
A projection screen includes a substrate, a reflective layer
having a first surface and an opposing second surface, and
diffusion layer. The second surface of the reflective layer is
attached (e.g., via an adhesive) to the substrate and the diffusion
layer is attached (e.g., via an optically transparent adhesive) to
the first surface of the reflective layer. The first surface of the
reflective layer has an unpolished (e.g., matte) finish. The
projection screen is preferably flexible and wound around a
conventional roller to form a projection screen system.
Alternatively, the projection screen may be attached to a rigid
substrate. In one embodiment, the diffusion layer includes two
surfaces, one of which is attached to the first surface of the
reflective layer and the other of which is outward facing. At least
the outward facing surface of the diffusion layer includes
irregularities to achieve a desired screen directivity
performance.
Inventors: |
Sinkoff; Howard; (Pompano
Beach, FL) |
Correspondence
Address: |
KEVIN P. CROSBY;BRINKLEY MCNERNEY MORGAN SOLOMAN & TATUM LLP
200 E. LAS OLAS BLVD, SUITE 1900
FORT LAUDERDALE
FL
33301
US
|
Family ID: |
29214818 |
Appl. No.: |
11/436192 |
Filed: |
May 18, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10719356 |
Nov 21, 2003 |
7057812 |
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11436192 |
May 18, 2006 |
|
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10125628 |
Apr 17, 2002 |
6724529 |
|
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10719356 |
Nov 21, 2003 |
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Current U.S.
Class: |
359/459 |
Current CPC
Class: |
G03B 21/602 20130101;
G03B 21/60 20130101 |
Class at
Publication: |
359/459 |
International
Class: |
G03B 21/60 20060101
G03B021/60 |
Claims
1. A projection screen comprising: a substrate; a reflective layer
having a first surface and an opposing second surface, the second
surface of the reflective layer being attached to the substrate,
the first surface of the reflective layer having an unpolished
finish; and a diffusion layer attached to the first surface of the
reflective layer.
2. The projection screen of claim 1, wherein the reflective layer
comprises aluminum.
3. The projection screen of claim 1, wherein the first surface of
the reflective layer has a matte finish.
4. The projection screen of claim 1, wherein the second surface of
the reflective layer has a polished finish.
5. The projection screen of claim 1, wherein the diffusion layer is
a resin.
6. The projection screen of claim 5, wherein the resin is one of
polyethylene and polypropylene.
7. The projection screen of claim 1, further comprising an
optically transparent adhesive that attaches the diffusion layer to
the first surface of the reflective layer.
8. The projection screen of claim 1, further comprising an adhesive
that attaches the first surface of the substrate to the second
surface of the reflective layer.
9. The projection screen of claim 1, wherein the diffusion layer
has a thickness greater than one one-thousandth of an inch (one
mil).
10. The projection screen of claim 9, wherein the thickness of the
diffusion layer is in the range of approximately two mils to
approximately eight mils.
11. The projection screen of claim 1, wherein the substrate
comprises polyvinylchloride and has a thickness in the range of
approximately five mils to approximately eight mils.
12. The projection screen of claim 1, wherein the reflective layer
has a thickness in the range of approximately one-third of a mil to
approximately one mil.
13. The projection screen of claim 1, wherein the substrate, the
reflective layer and the diffusion layer are sufficiently flexible
to enable the projection screen to be wound around a roller during
periods of non-use.
14. The projection screen of claim 1, wherein the diffusion layer
includes a first surface and an opposing second surface, the second
surface of the diffusion layer being attached to the first surface
of the reflective layer, at least the first surface of the
diffusion layer including a plurality of irregularities.
15. The projection screen of claim 14, wherein the plurality of
irregularities comprises a plurality of micro lenses.
16. The projection screen of claim 14, wherein plurality of
irregularities constitute a matte finish.
17. A projection screen system comprising: a projection screen that
includes: a substrate; a reflective layer having a first surface
and an opposing second surface, the second surface of the
reflective layer being attached to the substrate, the first surface
of the reflective layer having an unpolished finish; and a
diffusion layer attached to the first surface of the reflective
layer; and a roller around which the projection screen is wound
when the projection screen is not in use.
18. The projection screen system of claim 17, wherein the first
surface of the reflective layer has a matte finish.
19. The projection screen system of claim 17, wherein the diffusion
layer includes a first surface and an opposing second surface, the
second surface of the diffusion layer being attached to the first
surface of the reflective layer, at least the first surface of the
diffusion layer including a plurality of irregularities.
20. A projection screen comprising: a substrate; a reflective layer
having a first surface and an opposing second surface, the second
surface of the reflective layer being attached to the substrate,
the first surface of the reflective layer having an unpolished
finish; a diffusion layer coupled to the reflective layer such that
the reflective layer is positioned between the substrate and the
diffusion layer, the diffusion layer including a plurality of
irregularities to achieve a desired directivity.
21. The projection screen of claim 20, wherein the first surface of
the reflective layer has a matte finish.
22. The projection screen of claim 20, wherein the plurality of
irregularities comprises a plurality of micro lenses.
23. The projection screen of claim 20, wherein the second surface
of the reflective layer has a polished finish.
24. The projection screen of claim 20, wherein the diffusion layer
has a thickness greater than one one-thousandth of an inch (one
mil).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S.
application Ser. No. 10/719,356, which is a continuation-in-part of
U.S. application Ser. No. 10/125,628 (now U.S. Pat. No. 6,724,529),
and hereby claims priority upon such co-pending application under
35 U.S.C. .sctn.120.
BACKGROUND OF THE INVENTION
[0002] This invention relates to reflection-type projection
screens. More particularly, the invention relates to
reflection-type projection screens having excellent reflection
directivity in the horizontal and vertical directions yet which
produce a reflected image having superior gain and contrast.
[0003] The desirability of producing reflection-type projection
screens having a wide angle of reflectivity with suitable contrast
is well known. In settings such as movie theaters and home viewing
areas, the viewer is often times positioned at a significant angle
with respect to the direction of the projected image from the
projector, i.e. the direction of incident projected light.
Therefore, the screen must have an effective viewing angle greater
than would be producible if a highly reflective medium were used
alone.
[0004] Numerous attempts have been made to remedy this problem.
U.S. Pat. No. 3,653,740 to Ogura ("the '740 Patent") discloses a
projection screen having a double rolled aluminum foil sheet
attached to a support member, and a brushed resin film covering the
foil as a protective coating against scratching, fingerprints, etc.
No mention is made of the brushing techniques used or of the
resulting surface characteristic of the resin film after it is
brushed.
[0005] U.S. Pat. No. 6,144,491 to Orikasa ("the '491 Patent")
discloses a reflection-type projection screen having a substrate, a
light reflecting layer made from a transparent resin in which
flakes of a light-reflective material are dispersed, and a
transparent light-diffusing layer made from a transparent resin in
which fine crystalline particles of calcite and a pigment are
dispersed. The films of '491 Patent are complicated, expensive and
particularly difficult to achieve.
[0006] U.S. Pat. No. 6,040,941 to Miwa ("the '941 Patent")
discloses a reflection-type projection screen having a
light-reflecting substrate laminated to a light-transmitting
polymer layer having light absorptive slits or "crazes" of regular
directionality disposed therein. The slits are filled with a
light-absorbing substance such as a black pigment or dye.
[0007] U.S. Pat. No. 6,233,095 B1 to Niwa ("the '095 Patent")
discloses a reflex-type screen comprised of a first layer formed
integrally with an inner reflex layer on a surface of a substrate,
and a second layer formed of a deflection film bonded to a surface
of the first layer. The screen of the '095 Patent was developed to
facilitate the use of screens which can be deflected, e.g. rolled
up when not in use. Beads such as acrylic or silicon beads are
applied to the substrate surface prior to deposition of a metal
reflective layer, rendering the process of attaching the metal
reflective layer all the more complicated.
[0008] U.S. Pat. No. 5,456,967 to Nezu ("the '967 Patent")
discloses a reflection-type screen of the type that can be wound up
in a roll form and unwound as needed and comprises a substrate
sheet to which is laminated a high-density light
diffusion-reflection layer and a translucent light diffusion layer
including a soft vinyl chloride sheet, the translucent light
diffusion layer having a surface provided with a light-diffusing
fine uneven pattern.
[0009] U.S. Pat. No. 5,361,163 to Matsuda ("the '163 Patent")
discloses a reflection-type projection screen comprising a dark
plastic substrate, a fibrous sheet of glass fibers, a white, opaque
base material sheet and a light diffusing layer of a translucent
plastic onto which a lustrous pigment or calcite powder is
incorporated. An emboss is formed on the outer surface of the light
diffusion layer. Light absorbing strips are provided each at a
position corresponding to a concave portion of the emboss on the
surface of the base material sheet adjoining the light diffusing
layer.
[0010] U.S. Pat. No. 5,148,309 to Yamada ("the '309 Patent")
discloses a reflective type screen comprising a reflective surface
layer, a polarizing plate layer in position in front of the
reflective surface layer, and a diffusion layer located in front of
the polarized plate layer, wherein the reflective surface layer,
the polarizing plate layer and the diffusion layer are laminated
together using an adhesive to form an integral structure.
Additional embodiments are disclosed in the '309 Patent, all of
which require a polarizing layer, perhaps to accommodate exotic
applications of projection images onto a screen.
[0011] U.S. Pat. No. 4,232,939 to Kikuchi ("the '939 Patent")
discloses a transparent base plate to which is attached on one side
an aluminum mirror surface and on the other side a diffusing
specular layer of low diffusing performance. The diffusing
performance of the diffusing specular layer can be adjusted as
desired while the reflection performance of the mirror surface is
constant. The diffusing specular layer is formed with a plurality
of elongated columnar lenticles having convex surfaces facing the
viewer. The curvature of the lenticles is determined by the
distance between the screen and the viewers. The outer convex
surface of the lenticles is treated by sandblasting. The lenticles
are arranged in a vertically elongated pattern, which sacrifices
vertical directivity.
[0012] U.S. Pat. No. 4,201,449 to Campion ("the '449 Patent")
teaches a front projection screen having a substrate, a reflective
aluminum ink coating applied to a surface of a substrate, and a
protective coating, preferably of a clear acrylic having a gloss
finish for the purpose of protecting the reflective film. The
disclosure specifies that the coating reduces somewhat the
reflective efficiency of the screen. Therefore, the directionality
of such a screen is likely to be extremely narrow.
[0013] U.S. Pat. No. 4,190,320 to Ferro ("the '320 Patent") teaches
a front projection screen having two reflecting layers separated by
a light transmissive layer, and a light-diffusing surface coating
provided on the frontmost reflecting layer. The screen forms an
embossed pattern across its front surface.
[0014] U.S. Pat. No. 4,089,587 to Schudel ("the '587 Patent")
discloses a projection screen having a film which is constructed of
a partially deformable, resilient material. One surface of the film
has in combination a random matte texture and a substantially
unidirectional striated, i.e. grooved, texture. A layer of
reflective material is deposited on the above-mentioned surface of
the film to provide a high gain, damage resistant reflective
surface. The screen of the '587 Patent is intended to be of the
double-coverture type, i.e. curved about at least two axes so as to
focus the reflected image in a confined area. Another embodiment of
the '587 Patent discloses a flat screen. Striations are provided,
usually vertically aligned to disburse the light reflected off of
the reflective film. The arrangement of the striations or lenticles
as vertical grooves limits the directionality to nearly a
side-by-side viewing field and not top to bottom or diagonal.
SUMMARY OF THE INVENTION
[0015] It is therefore, an object of this invention to provide a
front projection screen that overcomes the aforementioned
disadvantages and shortcomings.
[0016] It is also an object of this invention to provide a front
projection screen that provides the same directionality (i.e.,
directivity) along vertical as well as horizontal axes relative to
a normal line passing perpendicularly through the center of the
projection screen.
[0017] It is a further object of this invention to provide a
projection screen that is simple and inexpensive to manufacture and
light weight yet which provides directivity characteristics not
heretofore experienced.
[0018] It is a further object of the present invention to provide
an improved directivity projection screen that is flexible and
capable of being rolled around a roller to form a composite and
optionally portable projection screen system.
[0019] In accordance with these and other objects, the present
invention is directed to a projection screen comprised of a
reflective film laminated, as by the use of adhesive, metal
deposition, or otherwise as will occur to those of skill in the
art, to a light diffusing layer on one side and, on another side,
as by adhesive, metal deposition, or other techniques known to
those of skill in the art, to a substrate. The substrate may be
rigid or flexible, flat or curved.
[0020] The reflective film may be vacuum metalized silver or vacuum
metalized aluminum or any other film exhibiting a high coefficient
of reflectivity. The characteristics of the light diffusing layer
can be adjusted depending upon the desired effect, intensity of
projected image light, ambient conditions, etc. One form of the
diffusing layer is an embossed film. One form of such embossed film
contains a plurality of concavities embossed in the film that act
as micro lenses. The surface characteristics (e.g., concavities)
associated with the light diffusing layer can be formed by
techniques such as hot roll stamping, ultra etching or the like.
Another form of such embossed film contains a plurality of
irregularities on at least one surface thereof. Such irregularities
are preferably in the form of a matte surface fabricated by rolling
or comparable techniques.
[0021] The reflective layer may be adhered to the substrate or to
the substrate-facing inner surface of the light diffusing
layer.
[0022] It can therefore be appreciated that one embodiment of the
invention is to a projection screen comprising a substrate; a
reflective layer having a first surface and an opposing second
surface, the second surface of the reflective layer being attached
to the substrate, the first surface of the reflective layer having
an unpolished finish; and a diffusion layer attached to the first
surface of the reflective layer.
[0023] These and other objects and features of the invention will
be more readily understood from a consideration of the following
detailed description, taken with the accompanying drawings, in
which corresponding parts are indicated by corresponding
numerals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a cross-sectional, elevational, exploded view of a
generalized embodiment of the invention.
[0025] FIG. 2 is a cross-sectional, elevational, exploded view of
an alternative embodiment of the invention.
[0026] FIG. 3 is a perspective, partial cutaway, view of the
alternative embodiment shown in FIG. 2.
[0027] FIG. 4 is a perspective exploded partial cutaway view of the
alternative embodiment of FIGS. 2 and 3.
[0028] FIG. 5 is a flow diagram of the method of the invention.
[0029] FIG. 6 is a cross-sectional, elevational, exploded view of a
projection screen in accordance with another alternative embodiment
of the present invention.
[0030] FIG. 7 is a perspective, partial cutaway, view of the
alternative projection screen shown in FIG. 6.
[0031] FIG. 8 is a perspective view of a projection screen system
in accordance with a further alternative embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0032] Referring now to the drawings, the screen of the first
embodiment of the invention is indicated by the reference numeral
10 and includes a substrate 15, which may be planar or curved
depending upon the requirements of the particular application, and
which, in the preferred embodiment, is of the rigid foam core
variety with plastic sheet panels on both sides for rigidity.
Although the screen of this invention can be used for any front
projected image, it is particularly suitable for use with LCD
projection or DLP and the like projection systems. The substrate is
commonly found in, and is preferably in, the thickness range of
between 1/4 inch and 2 inches. The thickness of the substrate 15 is
dictated by such parameters as strength requirements for a given
size of screen, the environment in which the screen will be used,
etc. The substrate defines a forward-facing or front surface
17.
[0033] A reflective, preferably metalized, film layer 20 is
included, which defines a forward facing, reflective, surface 22
and a rear surface 24 adapted to be connected to or placed adjacent
to, surface 17 of substrate15.
[0034] A light diffusing layer 30 is employed which sandwiches the
reflective layer 20 between light diffusing layer 30 and front
surface 17 of substrate 15. Layer 30 defines a forward facing
surface 32 and a rear facing surface 34. Rear surface 34 is
disposed adjacent to forward surface 22 of reflective layer 20.
[0035] Reflective layer 20 may be adhered to rear surface 34 of
light diffusing layer 30 by any suitable means, such as metallic
deposition or using transparent adhesive, etc. If an adhesive is
used, it should be an optically transparent formulated adhesive
that is transparent to light. Reflective layer 20 may alternatively
be applied to the rearward facing surface 34 of light diffusing
layer 30 or to forward facing surface 17 of substrate 15 by vacuum
metalization. The preferred materials which constitute layer 20 are
silver or aluminum. Still further, reflective layer 20 may be a
metal film such as aluminum, and may have a high polished mirror
finish, a matte finish or any other surface treatment deemed
desirable by one of skill in the art.
[0036] The light diffusing layer 30 is preferably fabricated of a
resin such as polyethylene, polypropylene or other material which
will permit light energy to enter through forward facing surface 32
and to be reflected by reflective layer 20 back through light
diffusing layer 30 but in a manner which will increase the viewing
angle of the reflected image such that the image can be seen from a
wide angle relative to a line I representing a projected image
light ray or wave projected at screen 10.
[0037] The higher the angle of diffusion, the wider the angle of
viewing that will be perceived by those watching the image
reflected by the screen. Normally, increasing the angle of
diffusion results in a decrease in the luminance of reflected
light. The make-up and physical contouring of light diffusing layer
30 is chosen so as to maximize the diffusion angle while also
maximizing the luminance of reflected light. Simultaneously, the
contrast of the reflected image should be kept as high as possible
for greater picture clarity. An ideal range of thickness of light
diffusing layer 30 is between 2-8 mils.
[0038] The ambient light characteristics, as well as the light
intensity of the projected image, dictate the particular
characteristics chosen for the light diffusing layer 30. Under
conditions where less diffusion is required such as in a setting
where the viewing angle does not need to be as great, polyethylene
can be used as a constituent of light diffusing layer 30. For
viewing settings where a greater angle of diffusion is desired,
polypropylene can be used as a constituent of light diffusing layer
30. The forward surface 32, or the rearward surface 34, or both, of
light diffusing layer 30 can be treated and/or contoured as by
random embossing, micro lensing, sandblasting or any equivalent
thereto indicated as reference number 35 in FIG. 1. Treatment 35
effects the magnitude of diffusion of the reflected image exiting
light diffusing layer 30.
[0039] As seen in FIGS. 2-4, an alternative or second embodiment of
the invention comprises a front projection screen 40 in which a
substrate 45, which may be similar to that described in connection
with FIG. 1, is provided, and which defines a front surface 47. A
reflective layer 50 is employed, also as disclosed in connection
with FIG. 1, including forward facing reflective surface 52. A
light diffusing layer 60 is employed, which defines forward surface
62 and rear surface 64. In this alternative embodiment, layer 60
defines a plurality of micro lenses M, which are, preferably,
concavities in the shape of semi spheres, prisms, parabaloids, or
any other raised structure which functions as a lens or prism with
respect to light incident thereupon. Layer 50 may be laminated to
inner surface 64 of light diffusing layer 60 (or to forward facing
surface 47 of substrate 45) by a transparent adhesive (not shown),
by vacuum deposition, or any other technique which will occur to
one of skill in the art. Layer 50 may be made of any of the
compositions discussed in connection with layer 20 of FIG. 1. Micro
lenses M may be formed in light diffusing layer 60 by ultra
etching, embossing, hot stamp rolling, or any other forming
technique which will yield small lens-shaped concavities or solid
embossed light-refracting elements therein. Micro lenses M may also
be formed in other shapes, such as micro prisms, similar to those
manufactured by Reflexsite Corporation.
[0040] The dimensions of the micro lenses such as a radius of
curvature for curved lenses M, or the height and slope of sides if
micro prisms are used, can be varied to effect the diffusion
properties of diffusion layer 60. A larger radius of curvature, or
a shallower slope, respectively, will yield smaller diffusion
angles, and smaller radii of curvature, or steeper prism slopes,
respectively will yield larger diffusion angles. For a home
projection television, a higher diffusion angle is preferred, while
in a movie theater setting a lower diffusion, higher concentrated,
light reflectivity could be tolerated.
[0041] The luminance of reflected light (i.e., gain) of reflective
layers 20 and 50 can be made lower for home television
applications, while the same characteristics of screens 10, 40,
respectively, can be increased for the commercial (e.g., movie
theater) application.
[0042] It is to be understood that the particular surface
treatments and/or contouring of light diffusing layers 30 and 60
herein can be brought about by any suitable means which will occur
to one of skill in the art. The addition of protective films (not
shown) over the outer surfaces 32, 62 of light diffusing layers 30,
60, respectively, is also contemplated to be within the scope of
the invention, if desired.
[0043] Screens as disclosed herein are suitable for use in dark or
full daylight conditions, and provide visual performance
characteristics not hereto before known. It is to be understood
that variations in materials and dimensions are contemplated to be
within the scope of this invention without departing without the
spirit hereof.
[0044] A method, depicted schematically in FIG. 5, is also
disclosed for creating the screen of this invention. The method
comprises the steps of: providing a suitable diffusion layer;
forming micro lenses in the diffusion layer; depositing the
reflective layer thereon; and mating the diffusion layer/reflective
layer composite to the substrate. In this way, very inexpensive yet
high performance projection screens in conformance with the
invention can be provided.
[0045] FIG. 6 is a cross-sectional, elevational, exploded view of
an exemplary projection screen 100 in accordance with another
alternative embodiment of the present invention. The projection
screen 100 includes a substrate 101, two adhesive layers 103, 104,
a reflective layer 106, and a diffusion layer 108. The substrate
101 is preferably flexible and constructed from polyvinylchloride
(PVC) or some other comparable substrate material. The substrate
101 has a thickness preferably in the range of approximately five
(5) mils to approximately eight (8) mils. The thickness of the
substrate 101 is dictated by parameters such as strength
requirements for a given size of the projection screen 100, the
environment in which the projection screen 100 will be used, and
the desired flexibility of the projection screen 100. Similar to
the substrates 15, 45 of FIGS. 1-4, the substrate 101 of FIG. 6
defines a forward-facing or front surface 110. The substrate 101
may also define an opposed rear surface 120 that may be optionally
secured by any conventional method to a rigid substrate depending
on the desired use of the projection screen 100.
[0046] The reflective layer 106 is preferably substantially
identical to reflective layer 20 disclosed above with respect to
FIG. 1. Accordingly, the reflective layer 106 preferably comprises
a metallic film, such as a film or foil of aluminum, and has a
thickness in the range of approximately 1/3 mil to one (1) mil.
When commercial grade aluminum foil is used as the reflective layer
106, such foil typically includes two opposed surfaces 112, 114
having different reflectivity characteristics. For example, as
noted above with respect to reflective layer 20, one surface of the
reflective layer 106 may have a high polished mirror finish and the
other surface may have a matte finish. Depending on the desired
brightness of the image displayed on the projection screen 100, a
surface with either finish may serve as the front surface 114 and
be attached to the diffusion layer 108 as discussed in more detail
below. For example, when a brighter image is desired, the surface
of the reflective material having the greater reflectivity is used
as the front surface 114 of the reflective layer 106. On the other
hand, when a duller image is desired, the surface of the reflective
material having the lesser reflectivity is used as the front
surface 1 14 of the reflective layer 106.
[0047] The diffusion layer 108 is preferably substantially
identical to diffusion layer 30 of FIG. 1 and, therefore, is
preferably fabricated from a resin, such as polypropylene or
polyethylene. The thickness of the diffusion layer 108 is greater
than one (1) mil and is preferably in the range of approximately
two (2) mils to eight (8) mils, as is the thickness of diffusion
layer 30 disclosed above. The diffusion layer 108 includes a front
surface 118 and an opposed rear surface 116. The front surface 118
of the diffusion layer 108 preferably includes a plurality of
irregularities, such as those used to form a matte finish as
illustrated in exemplary form in FIG. 7. The matte finish or other
irregularities may be fabricated using a press roller or any other
conventional technique. The rear surface 116 of the diffusion layer
108 preferably includes a substantially smooth finish, but may
alternatively include a matte or other finish, or other
irregularities, depending on the desired diffusion characteristics
of the diffusion layer 108.
[0048] The adhesive layers 103, 104 are preferably very thin (e.g.,
in the range of about 1/4 to 1/2 mil) and are fabricated from a
commercially-available optically transparent adhesive. In
alternative embodiments, different adhesives in different
thicknesses may be used for the adhesive layers 103, 104; however,
use of an optically transparent adhesive is preferred for adhesive
layer 104. Adhesive layer 103 functions to attach the front surface
110 of the substrate 101 to the rear surface 112 of the reflective
layer 106. Adhesive layer 104 functions to attach the front surface
114 of the reflective layer 106 to the rear surface 112 of the
diffusion layer 108. Reflective layer 106 may alternatively be
applied to the rear surface 116 of the diffusion layer 108 and/or
to the front surface 110 of the substrate 101 by vacuum
metalization or other conventional techniques, instead of using
adhesives. In such a case, the adhesive layers 103, 104 would not
be used to form the projection screen 100.
[0049] When constructed with the substrate 101, the reflective
layer 106, the diffusion layer 108 and the adhesive layers 103, 104
as described above, the projection screen 100 has a thickness
preferably in the range of approximately eight mils (8) to
approximately twenty (20) mils. In addition, when so constructed,
the projection screen 100 is sufficiently flexible to enable it to
be wound around a roller during periods of non-use and then
expanded during periods of use. Moreover, as confirmed through
experiments conducted on the above-described projection screen 100,
use of a matte finish on the front surface 118 of the diffusion
layer 108 causes the directivity along a vertical axis relative to
a normal line passing perpendicularly through a center of the
projection screen 100 to be substantially the same as the
directivity along a horizontal axis relative to such normal line,
thereby providing enhanced directionality as compared to prior art
screens.
[0050] FIG. 8 is a perspective view of a projection screen system
200 in accordance with a further alternative embodiment of the
present invention. As depicted, the projection screen system 200
preferably includes the above-described projection screen 100, a
roller 201, and an optional bar or tube 203. The roller 201 and
optional bar 203 are conventional devices used in various
commercially available front projection screens, such as the
"Lectric I" projection screen which is available from Vutec
Corporation of Pompano Beach, Fla. The bar 203 may be used to aid
in raising and lowering, or more generally opening and closing, the
projection screen 100, and may include an attached handle (not
shown). In the system 200 depicted in FIG. 2, the projection screen
100 is wound around the roller 201 for storage when the projection
screen 100 is not in use. In such system 200, the rear surface 120
of the substrate 101 is preferably adjacent the roller 201 when the
projection screen 100 is wound around the roller 201, thereby
preventing the viewing surface 118 of the screen 100 from
contacting the roller 201 when the projection screen 100 is closed
and stored. The projection system 200 may form part of a fixed
system (e.g., in a conference room or classroom) or may comprise
part of a portable system as desired by the user.
[0051] Various modifications and alterations of this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention, and it is understood that
this invention is not limited to the illustrative embodiments set
forth hereinbefore.
* * * * *