U.S. patent application number 11/841693 was filed with the patent office on 2008-02-21 for screen.
Invention is credited to William J. Allen, Anurag Gupta, John M. Koegler, Lawrence C. Mann.
Application Number | 20080043327 11/841693 |
Document ID | / |
Family ID | 35615559 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080043327 |
Kind Code |
A1 |
Allen; William J. ; et
al. |
February 21, 2008 |
Screen
Abstract
A projection screen includes a plurality of passive elements
each having a sidewall surrounding a surface, wherein said sidewall
is configured to attenuate light.
Inventors: |
Allen; William J.;
(Corvallis, OR) ; Koegler; John M.; (Corvallis,
OR) ; Gupta; Anurag; (Corvallis, OR) ; Mann;
Lawrence C.; (Corvallis, OR) |
Correspondence
Address: |
HEWLETT PACKARD COMPANY
P O BOX 272400, 3404 E. HARMONY ROAD
INTELLECTUAL PROPERTY ADMINISTRATION
FORT COLLINS
CO
80527-2400
US
|
Family ID: |
35615559 |
Appl. No.: |
11/841693 |
Filed: |
August 20, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10966447 |
Oct 15, 2004 |
7274508 |
|
|
11841693 |
Aug 20, 2007 |
|
|
|
Current U.S.
Class: |
359/459 ;
427/163.3 |
Current CPC
Class: |
G03B 21/60 20130101;
B33Y 80/00 20141201 |
Class at
Publication: |
359/459 ;
427/163.3 |
International
Class: |
G03B 21/60 20060101
G03B021/60; B05D 5/06 20060101 B05D005/06 |
Claims
1-27. (canceled)
28. A method of forming a projection screen, comprising:
micro-embossing a plurality of passive elements on a substrate,
each element including a sidewall and a floor, said sidewalls being
tilted slightly and configured to attenuate light.
29. The method of claim 28, and further comprising forming a
scattering reflective surface on each surface of said passive
elements.
30. The method of claim 28, and further comprising: determining
ambient conditions in which said projection screen is to be
operated; and establishing dimensions of said passive elements
based on said ambient conditions.
31. The method of claim 30, wherein determining said ambient
conditions includes determining a location for at least one ambient
light source.
32. The method of claim 31, wherein establishing said dimensions
comprises elongating said passive elements with respect to a
horizontal axis.
33. The method of claim 31, wherein establishing said dimensions
comprises elongating said passive elements with respect to a
vertical axis.
34. The method of claim 30, wherein determining said ambient
conditions includes determining a viewing angle for said projection
screen.
35. The method of claim 30, wherein establishing said dimensions
includes establishing a depth of said sidewalls.
36. The method of claim 28, wherein micro-embossing said passive
elements comprises depositing a layer of material on said
substrate, depositing a mask on said layer of material using
contact printing, exposing said mask to light from a single point
source to form exposed sidewalls, and heating said layer of
material to cause said exposed sidewalls to consolidate said
exposed sidewalls, and removing unconsolidated material from said
layer of material such that extensions of said sidewalls are
substantially parallel to light from said single point source.
37. The method of claim 28, and further comprising applying at
least one surface treatment to said passive elements.
38. The method of claim 37, wherein applying said surface treatment
comprises applying matte white paint.
39. The method of claim 28, and further comprising applying a
plurality of surface treatments to said passive elements.
40. The method of claim 28, wherein applying said plurality of
surface treatments comprises applying a reflective surface
treatment to said floors and a light absorbing surface treatment to
said sidewalls.
41. The method of claim 28, and further comprising providing a
screen gain enhancement on surfaces of said passive elements.
42. The method of claim 41, wherein said screen gain enhancement
comprises mica.
43. The method of claim 41 wherein said screen gain enhancement
comprises glass beads.
44. The method claim 28, wherein micro-embossing said passive
elements comprises three-dimensional printing.
45. The method of claim 28, wherein micro-embossing said passive
elements further comprises etching.
46. (canceled)
47. The method of claim 28, wherein micro-embossing said passive
elements comprises depositing a light sensitive material, forming a
mask on said light sensitive material, exposing said light
sensitive material to light to form exposed and unexposed portions,
consolidating said exposed portions, and removing said unexposed
portions.
48. The method of claim 47, wherein depositing said light sensitive
material includes depositing SU8 epoxy.
49. The method of claim 28, wherein micro-embossing said passive
elements comprises forming generally hexagonal passive
elements.
50. The method of claim 28, wherein micro-embossing said passive
elements comprises forming generally rectangular passive
elements.
51. The method of claim 28, wherein micro-embossing said passive
elements comprises forming generally square passive elements.
52. The method of claim 28, wherein micro-embossing said passive
elements comprises forming generally circular passive elements.
53-65. (canceled)
Description
[0001] This application is a divisional of Ser. No. 10/966,447,
filed Oct. 15, 2004, which is hereby incorporated by reference.
BACKGROUND
[0002] A popular class of display system is a front projection
system. A front projection system projects an image onto a
reflective screen which displays the image. Front projection
systems are generally suited for relatively dark rooms because
front projection screens indiscriminately reflect light incident to
the surfaces with substantially equal efficiency. Light from the
projector can be diluted by light from room lights, windows,
pixel-to-pixel interference, and/or other ambient light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The accompanying drawings illustrate various embodiments of
the present apparatus and method and are a part of the
specification. The illustrated embodiments are merely examples of
the present apparatus and method and do not limit the scope of the
disclosure.
[0004] FIG. 1 illustrates a schematic view of an exemplary display
system that includes an exemplary passive projection screen
according to one exemplary embodiment.
[0005] FIG. 2 illustrates an exemplary passive projection screen
according to one exemplary embodiment.
[0006] FIG. 3A illustrates a partial cutaway side view of an
exemplary passive element of a passive projection screen according
to one exemplary embodiment.
[0007] FIG. 3B illustrates a frontal view of an exemplary passive
element of a passive projection screen according to one exemplary
embodiment.
[0008] FIG. 4 illustrates a schematic view of an exemplary passive
projection screen according to one exemplary embodiment.
[0009] FIG. 5 illustrates a schematic view of an exemplary display
system according to one exemplary embodiment.
[0010] FIG. 6 is a flowchart illustrating an exemplary method of
forming a passive projection screen according to one exemplary
embodiment. Throughout the drawings, identical reference numbers
designate similar, but possibly not identical, elements.
DETAILED DESCRIPTION
[0011] An embodiment of a screen, such as a passive projection
screen, is provided herein that has a plurality of individual
passive elements formed thereon to enhance the contrast ratio of an
image displayed in the presence of ambient light. Further, the
passive projection screen may be formed of readily available
materials using fabrication techniques. These techniques may be
used to adjust the performance characteristics of the passive
projection display by varying the dimensions of the passive
elements.
[0012] An embodiment of a display system will be described herein
that makes use of an exemplary passive projection screen. The
passive projection screen will then be discussed, followed by a
discussion of the configuration of individual passive elements,
including passive elements that have angled sidewalls and passive
elements that are configured to be used with rear projection
systems. Thereafter, an exemplary method of forming a passive
projection screen will be discussed in more detail.
[0013] In the following description, for purposes of explanation,
numerous specific details are set forth in order to provide a
thorough understanding of the present method and apparatus. It will
be apparent, however, to one skilled in the art, that the present
method and apparatus may be practiced without these specific
details. Reference in the specification to "one embodiment" or "an
embodiment" means that a particular feature, structure, or
characteristic described in connection with the embodiment is
included in at least one embodiment. The appearance of the phrase
"in one embodiment" in various places in the specification may
possibly not be referring to the same embodiment.
Embodiment of a Display System Having a Passive Projection
Screen
[0014] FIG. 1 illustrates an exemplary display system (100)
according to one exemplary embodiment. In particular, the display
system (100) shown is a frontal projection system. The display
system (100) generally includes an embodiment of a passive
projection screen, such as passive projection screen (110), and an
exemplary projector assembly, projector assembly (120). The
projector assembly (120) described is exemplary only and may be
modified or changed as best serves a particular application.
[0015] Image data is input into an image processing unit (130). The
image data defines an image that is to be displayed by the
projector assembly (120). While one image is illustrated and
described as being processed by the image processing unit (130), it
will be understood by one skilled in the art that a plurality or
series of images may be processed by the image processing unit
(130). The image processing unit (130) performs various functions
including controlling the illumination of a light source (140) and
controlling a spatial light modulator (SLM) (150).
[0016] The light source (140) provides a beam of light to the
spatial light modulator (150). The light source (140) may be, but
is not limited to, a high pressure mercury lamp, a xenon bulb, or
an array of light emitting diodes.
[0017] The incident light may be modulated in its phase, intensity,
polarization, or direction by the modulator (150). Thus, the SLM
(150) of FIG. 1 modulates the light output by the projector
assembly (120) based on input from the image processing unit (130)
to form an image-bearing beam (160) that is eventually displayed or
cast onto the passive projection screen (110).
[0018] The image-bearing beam (160), as well as ambient light (170)
from an ambient light source (180), are both incident upon the
passive projection screen (110). As will be discussed in more
detail below, the passive projection screen (110) directs a
substantial portion of the image-bearing beam (160) back toward a
viewer (190) or viewers within a viewing cone, while attenuating
the ambient light (170) directed back toward a viewer (190) or
viewers within a viewing cone. The attenuation of a portion of the
ambient light (170) increases the contrast ratio of the image
displayed on the passive projection screen (110). The configuration
of the passive projection screen (110) will now be discussed in
more detail.
Passive Projection Screen
[0019] FIG. 2 illustrates the passive projection screen (110) in
more detail. The passive projection screen (110) includes a
plurality of individual passive elements (200) formed thereon to
enhance the contrast ratio of an image displayed in the presence of
ambient light. As previously discussed, the individual passive
elements (200) direct light from a display system back toward a
user while reducing the amount of light from ambient sources that
is directed back to the viewers.
[0020] The passive projection screen (110) is composed of a matrix
of individual passive elements (200) in the form of hexagonal
wells. The matrix of hexagonal passive elements (200) forms a
honeycomb pattern. As will be discussed in more detail below, the
design of the passive projection screen (110) can be adjusted to
vary the angle of view versus the degree of rejection of ambient
light. In particular, the height of the walls of each of the
passive elements (200) may be increased to attenuate more light. As
the height of the walls of the passive element increases, the size
of the viewing cone decreases. Accordingly, the height of the
passive elements (200) may be adapted for the viewing cone to be
used in any given application. The exemplary passive elements (200)
discussed with reference to FIG. 2 are generally hexagonal in shape
and may, according to one exemplary embodiment have a size of
approximately 0.2 mm to about 1.0 mm or more with sidewalls having
aspect ratios (height divided by width) of about 10:1 or 20:1. The
elements may be of any suitable size and shape. For example, other
shapes include, without limitation, squares, rectangles, and
circles.
[0021] Further, the passive projection screen (110) can be tuned
independently for rejecting ambient light from the light sources
located above or below the projection screen or for rejecting
ambient light located to the sides of the projection screen. The
configuration of the passive projection screen (110) will now be
discussed in more detail with reference to an individual passive
element (200).
Configuration of Individual Passive Elements
[0022] FIGS. 3A-3B illustrates an individual element, such as a
passive element, in more detail. In particular, FIG. 3A illustrates
a cutaway side view of an individual passive element (200), while
FIG. 3B illustrates a front view of the passive element (200). As
shown in FIG. 3A, the passive element (200) includes a front plane
(300) and a rear plane or floor (310). A hexagonal well is formed
in the front plane (300) such that the second or rear plane (310)
forms a floor that is surrounded by sidewalls (320). The sidewalls
(320) shown are substantially perpendicular (within the range of
variation that may result from the technique used to fabricate the
passive element) to both the front and rear planes (300, 310). In
one exemplary embodiment, the sidewalls (320) and the floors are
each covered with matte white paint and treated to act as
scattering reflectors.
[0023] Further, as shown in FIG. 3A, ambient light (170) from an
ambient light source (180), such as a ceiling light fixture, that
is incident on the passive element (200) is far from normal with
respect to the rear plane (310). Accordingly, the sidewalls (320)
shade some of the rear plane (310) from this high-angle ambient
light. Consequently, this ambient light is not efficiently directed
into the eyes of viewers. Alternatively, projected light from the
image-bearing beam (160) arrives nearly parallel to the sidewalls
(320). The image-bearing beam (160) is then reflected out of the
passive element (200) and is relayed to the eyes of a viewer or
audience. Accordingly, a substantial portion of the image-bearing
beam (160) is perceived by a viewer or audience while at least some
of the ambient light (170) is reflected away from the viewer or
audience. The portion of incident ambient light (170) that is
reflected away from the viewer or audience may be controlled by
varying the dimensions of the passive elements, including the depth
of the sidewalls (320).
[0024] Deeper sidewalls (320) increase the contrast ratio by
reducing the amount of ambient light that reaches the viewer.
However, there is a tradeoff between the contrast ratio and the
angle of view. More specifically, as the sidewalls (320) increase
in depth, portions of the image-bearing beam (170) are also
attenuated from the viewer by the sidewalls (320). Consequently,
the depth of the sidewalls (320) affects, at least in part, the
contrast ratio and viewing angle of the passive projection screen
(110).
[0025] In one exemplary embodiment, a passive projection screen
(110; FIG. 1) includes a plurality of passive elements (200) each
having dimensions of approximately 0.5 mm in depth by approximately
1.0 mm in width and height. The base and sidewalls (320) of the
exemplary embodiment were deposited using three-dimensional
printing techniques. In addition, the surfaces of the sidewalls
(320) and rear planes (310) were coated with a matte white
paint.
[0026] The performance characteristics of the passive projection
screen (110; FIG. 1) were then analyzed under controlled high
ambient light conditions and dark conditions and compared to the
optical characteristics of an 81/2''.times.11'' size sheet of
high-quality printer paper when receiving light from a typical
digital projector. The results of the comparison are summarized
below, in which the sensed light from the passive projection screen
are characterized by the designation "Hex" and the sensed light
from the sheet of paper is designated as "Paper." The pixels
displayed are either white (W) or black (K) in order to calculate
the maximum contrast ratio (CR). TABLE-US-00001 Light coming off
screen (cd/m.sup.2) to viewer centered in front of screen
Fluorescent Lights On Fluorescent Lights Off Hex W 547 348 Hex K
195 0.52 Hex CR 2.8 669 Paper W 705 413 Paper K 303 0.63 Paper CR
2.3 656
[0027] As shown above, with the ambient lights on, the passive
projection screen attenuated the ambient light and increased the
contrast ratio from 2.3 with a plain white surface to 2.8 with the
passive projection screen. In the dark, where ambient light was
substantially reduced, the structure of the passive projection
screen had very little effect on the contrast ratio. Accordingly,
the hexagonal structure of the individual passive elements
increases the contrast ratio of a displayed image.
[0028] As previously discussed, the dimensions of each of the
passive elements (200) may be varied or adjusted to control the
performance characteristics of the passive projection screen (110;
FIG. 1). In particular, the width of the passive elements (200),
which may be measured about a horizontal axis of the passive
element, may be approximately 200 .mu.m or less. Further, the width
and height of the passive elements (200) may be independently
varied to attenuate ambient light from overhead light sources
differently than light sources located to the sides of the passive
projection screen (110; FIG. 1).
[0029] The exemplary projector screen (110; FIG. 1) discussed above
included passive elements (200) having a single surface treatment
applied thereto to reduce the amount of light that is directed back
to the viewers. The projector screen (110; FIG. 1) may also be
treated with multiple surface treatments. For example, the
sidewalls (320) may be treated with a light absorbing surface
treatment, such as gloss black paint, while the rear plane (310)
may be treated with a diffuse reflecting surface, such as matte
white paint.
[0030] As previously discussed, light incident on such a screen
comes from a variety of sources. For example, an incoming light ray
that is nearly perpendicular to the rear plane (310), may graze one
of the sidewalls (320). The angle between such an incoming light
ray and the sidewall (320) will be beyond a critical angle of the
sidewall (320), and the incoming light ray will be substantially
reflected by the sidewall (320). Thereafter, the incoming light ray
will be incident on the rear plane (310), which then directs the
light ray to the viewer.
[0031] In other cases, a light ray that arrives nearly
perpendicularly to the sidewalls (320) will penetrate the light
absorbing surface treatment where the light is absorbed. By
absorbing a portion of the ambient light incident on each passive
element, the passive projection screen (110; FIG. 1) further
decreases the amount of ambient light directed back to a viewer,
thereby increasing the contrast ratio of an image displayed in the
presence of ambient light.
[0032] The passive projection screens described thus far have made
use of sidewalls that are generally perpendicular to the rear plane
or floors (310) of each of the passive elements. As shown in FIG.
4, a passive projection screen (110-1) may be formed having
sidewalls (320-1) that are tilted slightly. The size of the
sidewalls (320-1) has been exaggerated for ease of reference. The
sidewalls (320-1) shown are tilted such that if each of the
sidewalls were extended, they would converge near a single point
(not shown).
[0033] These sidewalls (320-1) may be formed using a photo imaging
process, which may include a contact print process. In such a
process, a layer of SU8 epoxy is first deposited to form the front
plane (300-1). Thereafter, a mask is formed that includes a field
of black hexagons separated by thin clear lines. The thin clear
lines correspond to the shape of the frontal view of the passive
elements (320-1). This mask is placed on the front plane (300-1),
such as through contact printing. Thereafter, the front plane
(300-1) with the mask applied thereto is exposed to light. Light
passes through the thin clear lines while the dark black hexagons
block the transmission of light. Light is thus selectively passed
through the thin clear lines to the SU8 material. As light passes
through the layer of material, it exposes the SU8 epoxy. This
exposed material is then consolidated in a post exposure baking
step, which causes molecular cross linking of the exposed SU8
epoxy. Thereafter, the unconsolidated material, which is the
material below the mask that has not been exposed, is removed
leaving the consolidated material of the sidewalls (320-1).
Accordingly, the material that is exposed and later consolidated to
form the sidewalls depends, at least in part, on how light is
directed to the mask.
[0034] The light used in exposing the layer of SU8 epoxy may be
provided by a single point source. The light passing through the
layers of SU8 would be parallel to rays of light drawn from the
point source, thereby exposing the material in the tilted fashion
shown in FIG. 4. As previously discussed, this exposed material is
later consolidated to form solid walls, after which the non-exposed
material is removed. As a result, the sidewalls (320-1) of passive
elements nearest the point source would have nearly perpendicular
walls, while other passive elements would have tilted walls.
Accordingly, the sidewalls would be tilted or biased toward a
single point. The resulting passive projection screen (110-1) may
focus light from the area of a single source, thereby reducing the
amount of ambient directed to the viewer. Accordingly, the
dimensions of the passive elements may be varied to control several
performance characteristics.
[0035] Further, the passive elements may be adapted for use with
rear projection display systems. For example, as shown in FIG. 5,
an embodiment of a rear projection display system (500) includes a
passive projection screen (110-2) configured to be used with a rear
projection assembly (510). In such a configuration, the rear plane
(310; FIG. 3) of each of the passive elements (300; FIG. 3) is
formed of a transparent material. As a result, light from the rear
projection assembly (400) is able to pass through the passive
projection screen (110-2) to be viewed by a viewer (190) or
viewers. Further, the sidewalls (320; FIG. 3) of each of the
passive elements (300; FIG. 3) shields a portion of the rear plane
(310; FIG. 3) as previously discussed, thereby increasing the
contrast ratio of the image.
[0036] Accordingly, the passive projection screen attenuate ambient
light to thereby increase the contrast ratio of an image displayed
thereon. In addition, as will now be discussed in more detail,
passive projection screens may be readily formed. Further, the size
of the viewing angle, as well as the horizontal and vertical
ambient light dissipating properties of the passive projection
screens may be readily adjusted by varying the dimensions of the
passive elements.
Method of Forming a Passive Projection Screen
[0037] FIG. 6 is a flowchart illustrating an exemplary method of
forming a passive projection screen. As previously introduced, the
performance characteristics of the passive projection screen may be
adjusted to suit environmental conditions by varying the dimensions
of the passive elements. Accordingly, the exemplary method begins
by determining the ambient conditions (step 600). These ambient
conditions may include determining the likely location of ambient
light sources and the desired viewing angle of the passive
projection screen. For example, ambient light sources are
frequently located overhead, such as in ceiling light fixtures. In
other situations, light sources may be located primarily to the
sides of the passive projection screens, such as may be the case
where table lamps or wall lamps are used extensively. Further, some
applications allow the use of a relatively narrow viewing angle,
such as when the display system is located in a long, narrow room.
Other factors, which include without limitation, the geometry of
the projector, the geometry of the screen, and the characteristics
of the audience may also be used in determining the dimensions of
the passive elements.
[0038] These ambient conditions are then used to determine the
dimensions of the passive elements (step 610). For example, where a
higher contrast ratio is desired, the depth of the passive elements
may be relatively large. Further, in the case where ambient light
is provided primarily by overhead ambient light sources, the
passive elements may be elongated along a horizontal axis.
Similarly, where ambient light is provided primarily by ambient
light sources located to the side of the projection screen, the
passive elements may be elongated along a vertical axis.
[0039] The passive elements are formed on a substrate (step 620).
The substrate may be any suitable material, including materials
commonly used in forming projection screens. The passive elements
themselves may be formed of any suitable material, including,
without limitation, SU8 epoxy resin. Several approaches may be used
to form the passive elements that include, without limitation,
etching, micro-embossing, or three-dimensional printing.
[0040] Once the passive elements have been formed on the substrate
(step 620), the surfaces are coated with at least one surface
treatment (step 630). As previously discussed, the surfaces may be
covered with a single surface treatment, such as matte white paint,
to form surfaces which are scattering reflectors. These coatings
may be applied by any suitable means including, without limitation,
contact printing. Further, the surfaces may be treated with
multiple surface treatments, such as treating the surfaces of the
sidewalls with a light absorbing surface treatment while treating
the floors or rear planes of each of the passive elements with a
reflective material. Further, the rear planes of each of the
passive elements may be formed with a transparent substrate.
[0041] In addition, the surfaces may be treated with screen gain
enhancements (step 640) such as mica or glass beads that are
applied to the surfaces of the passive projection screen. These
particles increase the amount of light reflecting off the rear
plane of the passive projection screen and back to the viewer.
[0042] Accordingly, the present method provides for the formation
of a variety of passive projection screens. Formation of such
passive projection screens by the disclosed techniques reduces the
costs associated with production. Further, the present method
provides for the formation of passive projection screens with
characteristics that are well suited to the operating environment
of the display system.
[0043] The preceding description has been presented only to
illustrate and describe the present method and apparatus. It is not
intended to be exhaustive or to limit the disclosure to any precise
form disclosed. Many modifications and variations are possible in
light of the above teaching. It is intended that the scope of the
claimed subject matter be defined by the following claims.
* * * * *