U.S. patent application number 11/852683 was filed with the patent office on 2008-03-27 for light source assemblies.
This patent application is currently assigned to Bookham Technology plc. Invention is credited to Brett Bryars, Peter C. Egerton, Rance M. Fortenberry, Michael A. Scobey, Rad Sommer.
Application Number | 20080074898 11/852683 |
Document ID | / |
Family ID | 40075515 |
Filed Date | 2008-03-27 |
United States Patent
Application |
20080074898 |
Kind Code |
A1 |
Sommer; Rad ; et
al. |
March 27, 2008 |
LIGHT SOURCE ASSEMBLIES
Abstract
A light source assembly comprises: a light pipe and one or more
tapered light collectors operative to reduce the angular
distribution of light entering the light pipe from light sources at
one or more ports. Dichroic filters and angle-dependent, wavelength
selective pass filters control light flow into and through the
light pipe. The tapered light collector is operative to reduce the
angular distribution of light entering the light pipe. At least a
first dichroic filter positioned in the light pipe optically
between first and second light entrances is operative to pass first
color light from the first light source toward the light port, and
to reflect second color light from the second light source toward
the light port.
Inventors: |
Sommer; Rad; (Sebastopol,
CA) ; Egerton; Peter C.; (Windsor, CA) ;
Fortenberry; Rance M.; (Cazadero, CA) ; Bryars;
Brett; (Santa Rosa, CA) ; Scobey; Michael A.;
(Santa Rosa, CA) |
Correspondence
Address: |
BANNER & WITCOFF, LTD.
28 STATE STREET
28th FLOOR
BOSTON
MA
02109-9601
US
|
Assignee: |
Bookham Technology plc
Towcester
GB
NN12 8EQ
|
Family ID: |
40075515 |
Appl. No.: |
11/852683 |
Filed: |
September 10, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11501923 |
Aug 9, 2006 |
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11852683 |
Sep 10, 2007 |
|
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60939716 |
May 23, 2007 |
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60810317 |
Jun 2, 2006 |
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Current U.S.
Class: |
362/583 ;
362/551 |
Current CPC
Class: |
G02B 27/145 20130101;
H04N 9/3152 20130101; G02B 27/102 20130101; G02B 6/0026 20130101;
G02B 6/0068 20130101; G02B 27/142 20130101; G02B 6/0028
20130101 |
Class at
Publication: |
362/583 ;
362/551 |
International
Class: |
F21V 9/08 20060101
F21V009/08; G02B 6/00 20060101 G02B006/00 |
Claims
1. A light source assembly comprising, in combination: a light pipe
forming at least a light port and an elongate axial optical pathway
from first and second light entrances to the light port, the second
light entrance being axially spaced along the light pipe from the
first light entrance; a first tapered light collector at the first
light entrance, operative to reduce the angular distribution of a
first color light to be fed into the light pipe via the first
tapered light collector; a second tapered light collector at the
second light entrance, operative to reduce the angular distribution
of a second color light, different from the first color light, to
be fed into the light pipe via the second tapered light collector;
and at least a first dichroic filter positioned in the light pipe
optically between the first and second light entrances and
operative as oriented in the light pipe to pass first color light
from the first light source toward the light port, and to reflect
second color light from the second light source toward the light
port.
2. The light source assembly of claim 1 further comprising: a first
light source operative to generate first color light into the light
pipe at the first light entrance via the first tapered light
collector; and a second light source operative to generate second
color light, different from the first color light, into the light
pipe via the second tapered light collector.
3. The light source assembly of claim 2 wherein at least one of the
first and second tapered light collectors comprises a tapered
hollow light pipe fixedly integrated with the light pipe.
4. The light source assembly of claim 2 further comprising a short
wave pass filter positioned at the first or second light
entrance.
5. The light source assembly of claim 2 wherein the first dichroic
filter is positioned in the light pipe at a 30.degree. to
60.degree. angle to the axial optical pathway.
6. The light source assembly of claim 2 wherein the second light
entrance is located axially along the light pipe between the first
light entrance and the light port, and wherein the light source
assembly further comprises a primary second light entrance filter
positioned at the second light entrance in a plane generally
parallel to the elongate axial optical pathway, the second light
entrance filter being operative: c. to pass at least second color
light having an angle of incidence of from 0.degree. to 30.degree.
upon the primary second light entrance filter, and d. to reflect at
least i. second color light having an angle of incidence of from
60.degree. to 90.degree. upon the primary second light entrance
filter, and ii. first color light having an angle of incidence of
from 0.degree. to 30.degree. upon the primary second light entrance
filter.
7. The light source assembly of claim 6 wherein the primary second
light entrance filter is a short wave pass filter.
8. The light source assembly of claim 6 further comprising
reflective surface at the perimeter of at least one of the light
entrances operative to provide recirculation of at least a portion
of the light from the associated light source.
9. The light source assembly of claim 6 further comprising
reflective surface at the perimeter of the second light entrance,
and wherein a. the second light collector increases in size toward
an opening at the second light entrance into the light pipe, b. the
opening of the light collector is larger than the second light
entrance, and c. the reflective surface at the perimeter of the
second light entrance is operative to reflect back at least a
portion of the light from the second light source which does not
pass through the primary second light entrance filter.
10. The light source assembly of claim 6 further comprising a
secondary second light entrance filter positioned in the axial
optical pathway optically between the second light entrance and the
light port, the secondary second light entrance filter being
operative: a. to pass at least i. first color light having an angle
of 0.degree. to 30.degree. to the axial optical pathway to the
light port, and ii. second color light having an angle of 0.degree.
to 30.degree. to the axial optical pathway to the light port; and
b. to reflect at least second color light having an angle of
60.degree. to 90.degree. to the axial optical pathway to the light
port.
11. The light source assembly of claim 10 wherein the secondary
second light entrance filter is oriented normal to the axial
optical pathway.
12. The light source assembly of claim 10 wherein the secondary
second light entrance filter is a short wave pass filter.
13. The light source assembly of claim 2 further comprising: a. at
least one light valve positioned to receive light passed from the
light pipe via the light port, and b. at least one focusing relay
lens positioned between the light port and the light valve and
operative to focus light passed from the light pipe via the light
port to the light valve.
14. The light source assembly of claim 2 wherein the dichroic
filter has an index of refraction n greater than 1.9.
15. The light source assembly of claim 2 further comprising: a
third tapered light collector at a third light entrance to the
light pipe, the third light entrance being axially spaced from the
first and second light entrances and located between the second
light entrance and the optical port; a third light source operative
to generate a third color light, different from the first and
second color lights, into the light pipe via the third tapered
light collector, the third tapered light collector being operative
to reduce the angular distribution of the third color light
entering the light pipe from the third light source; and at least a
second dichroic filter positioned in the axial optical pathway
optically between the second light entrance and the third light
entrance, 30.degree. to 60.degree. angle to the axial optical
pathway, the second dichroic filter being operative to pass first
and second color light from the first and second light sources,
respectively, toward the light port and to reflect third color
light from the third light source toward the light port; wherein
the light pipe is operative to homogenize the first, second and
third color lights passed simultaneously to the light port from the
first, second and third light sources, respectively.
16. The light source assembly of claim 15 further comprising: a. a
primary second light entrance filter positioned at the second light
entrance in a plane generally parallel to the axial optical
pathway, the second light entrance filter being operative: i. to
pass at least second color light having an angle of incidence of
from 0.degree. to 30.degree. upon the primary second light entrance
filter, and ii. to reflect at least second color light having an
angle of incidence of from 60.degree. to 90.degree. upon the
primary second light entrance filter, and first color light having
an angle of incidence of from 0.degree. to 30.degree. upon the
primary second light entrance filter; and b. a primary third light
entrance filter positioned at the third light entrance in a plane
generally parallel to the axial optical pathway, the second light
entrance filter being operative: iii. to pass at least second color
light having an angle of incidence of from 0.degree. to 30.degree.
upon the primary second light entrance filter, and iv. to reflect
at least second color light having an angle of incidence of from
60.degree. to 90.degree. upon the primary second light entrance
filter, and first color light having an angle of incidence of from
0.degree. to 30.degree. upon the primary second light entrance
filter.
17. The light source assembly of claim 15 further comprising: a. a
secondary second light entrance filter positioned in the axial
optical pathway optically between the second light entrance and the
light port, the secondary second light entrance filter being
operative: i. to pass at least first color light having an angle of
0.degree. to 30.degree. to the axial optical pathway to the light
port, and second color light having an angle of 0.degree. to
30.degree. to the axial optical pathway to the light port; and ii.
to reflect at least second color light having an angle of
60.degree. to 90.degree. to the axial optical pathway to the light
port; and b. a secondary third light entrance filter positioned in
the axial optical pathway optically between the third light
entrance and the light port, the secondary third light entrance
filter being operative: i. to pass at least first, second and third
color light having an angle of 0.degree. to 30.degree. to the axial
optical pathway, and ii. to reflect at least third color light
having an angle of 60.degree. to 90.degree. to the axial optical
pathway.
18. The light source assembly of claim 15 wherein: a. the light
pipe comprises a hollow elongate rectangular pipe segment extending
from a first axial end of the rectangular pipe segment to the light
port at a second axial end of the rectangular pipe segment; b. the
first light entrance is an axial entrance at the first axial end of
the rectangular pipe segment; c. the second light entrance is a
lateral entrance through a side wall of the rectangular pipe
segment; and d. the third light entrance is a lateral entrance
through a side wall of the rectangular pipe segment.
19. The light source assembly of claim 15 wherein the first light
source comprises a green LED, the second light source comprises a
blue LED and the third light source comprises a red LED.
20. The light source assembly of claim 15 wherein the third light
source comprises a green LED.
21. The light source assembly of claim 15 wherein the first light
source is a red LED, the second light source is a green LED, and
the third light source is a blue LED.
22. The light source assembly of claim 1 wherein at least one of
the first and second tapered light collectors is an anamorphic
collector.
23. The light source assembly of claim 2 wherein at least one of
the first and second tapered light collectors is a focusing light
collector operative to focus light from the associated light source
into the light pipe.
24. The light source assembly of claim 2 wherein at least one of
the first and second tapered light collectors is a non-focusing
light collector.
25. A light source assembly comprising, in combination: an light
pipe forming at least a light port and an elongate axial optical
pathway to the light port; a first tapered light collector; a first
light source operative to generate a first color light into the
light pipe at a first light entrance via the first tapered light
collector, the first tapered light collector being operative to
reduce the angular distribution of the first color light entering
the light pipe from the first light source; a second tapered light
collector; a second light source operative to generate a second
color light, different from the first color light, into the light
pipe via the second tapered light collector at a second light
entrance axially spaced from the first light entrance, the second
tapered light collector being operative to reduce the angular
distribution of the second color light entering the light pipe from
the second light source; and at least a first dichroic filter
comprising a thin film filter and positioned in the light pipe
optically between the first and second light entrances and
operative as oriented in the light pipe-- to pass first color light
from the first light source toward the light port, and to reflect
second color light from the second light source toward the light
port.
Description
RELATED APPLICATIONS
[0001] This application claims the priority benefit of U.S.
Provisional Patent Application Ser. No. 60/939,716, filed May 23,
2007, entitled "LIGHT SOURCE ASSEMBLIES," the entire contents of
which are incorporated herein by reference for all purposes, and
this application is a continuation-in-part of commonly assigned and
co-pending U.S. patent application Ser. No. 11/501,923 entitled
LIGHT SOURCE ASSEMBLY WITH INTEGRATED OPTICAL PIPE, filed on Sep.
8, 2006, the entire disclosure of which is hereby incorporated by
reference for all purposes, which in turn claims the priority
benefit of, and incorporated by reference the entire contents of
U.S. Provisional Patent Application Ser. No. 60/810,317, filed on
Jun. 2, 2006.
INTRODUCTION
[0002] The inventive subject matter disclosed here involves a light
source assembly and, in particular, a light source assembly
comprising a light pipe, alternatively referred to as an optical
pipe.
BACKGROUND
[0003] Light source assemblies of various types are used to provide
light for projection systems and other optical equipment. Light
source assemblies able to collect, pass, homogenize and/or direct
light have various industrial and commercial applications. In
general, devising alternative light source assemblies or improving
currently known light source assemblies have proven difficult and
in some cases expensive to achieve. Substantial complexity and
commercial constraints exist in the various involved
technologies.
[0004] It is an objective of the present disclosure to provide
improved light source assemblies comprising an optical pipe and one
or more associated light sources comprising a light emitting diode
(LED) or other suitable light emitter.
SUMMARY
[0005] In accordance with a first aspect, a light source assembly
comprises a light pipe, at least a first and second light injection
port, and at least a first dichroic filter positioned in the light
pipe optically between the first and second light injection port.
In certain exemplary embodiments the light source assembly further
comprises a first light source operative to generate a first color
light at the first light injection port and a second light source
operative to generate a second color light at the second light
injection port, different from the first color light. The light
pipe forms at least an exit or downstream light port and an
elongate optical pathway to the light port from the light injection
ports. Each of the light injection ports comprises a first tapered
light collector. The tapered light collector is operative to pass
light emitted by the associated light source into the light pipe
via the associated light injection port (also referred to here in
some instances as a light entrance) and to reduce the angular
distribution of such light entering the light pipe from the light
source. Thus, at least certain embodiments of the light source
assemblies disclosed here are etendue preserving. The light
injection ports into the light pipe are axially spaced. Thus, a
first injection port is operative to inject light of the first
color into the light pipe. A second injection port operative to
inject light of a second color into the light pipe, is downstream
of the first light injection port, that is, it is optically closer
to the output port of the light pipe. The dichroic filter is
positioned in the light pipe optically between the first and second
light entrances. It is operative, as oriented in the light pipe, to
pass light from the first light source toward the light port and to
reflect the second color light from the second light source toward
the light port. In at least certain exemplary embodiments the light
pipe is operative to homogenize the first and second color lights
passed simultaneously to the light port from the first and second
light sources, respectively.
[0006] In accordance with a second aspect, a light source assembly
comprises a light pipe forming at least a light port and an
elongate axial optical pathway to the light port; a first tapered
light collector; a first light source operative to generate a first
color light into the light pipe at a first light entrance via the
first tapered light collector, a second tapered light collector; a
second light source operative to generate a second color light,
different from the first color light, into the light pipe via the
second tapered light collector at a second light entrance axially
spaced from the first light entrance; and at least a first dichroic
filter positioned in the light pipe optically between the first and
second light entrances. The dichroic filter is operative, as
oriented in the light pipe, to pass first color light from the
first light source toward the light port, and to reflect second
color light from the second light source toward the light port. The
light pipe is operative to homogenize the first and second color
lights passed simultaneously to the light port from the first and
second light sources, respectively. The first tapered light
collector is operative to reduce the angular distribution of the
first color light entering the light pipe from the first light
source, and the second tapered light collector is operative to
reduce the angular distribution of the second color light entering
the light pipe from the second light source.
[0007] Those of ordinary skill in the art will recognize that the
light source assemblies disclosed here present significant
technical and commercial advantages. Likewise, those of ordinary
skill in the art will recognize that innumerable modifications can
be made and other features are aspect added without departing from
the principles disclosed here.
[0008] A light source assembly for providing a homogenized light
beam includes a first light source, a second light source, and an
optical pipe that defines a pipe passageway. The first light source
generates a first light that is directed into the pipe passageway
at a first region. The second light source generates a second light
that is directed into the pipe passageway at a second region that
is different than the first region. The optical pipe homogenizes
the first light and the second light. With this design, the present
invention provides a way to combine multiple lights to generate a
uniform light beam with a relatively small package.
[0009] Additionally, the light source assembly can include a third
light source that generates a third light that is directed into the
optical pipe at a third region that is different than the first
region and the second region. In this embodiment, the optical pipe
homogenizes the first light, the second light, and the third light.
With this design, one of the light sources can be a red LED that
generates red light, one of the light sources can be a blue LED
that generates blue light, and one of the light sources can be a
green LED that generates green light.
[0010] Additionally, the light source assembly can include a blue
pass filter that is positioned between the blue LED and the pipe
passageway. The blue pass filter (i) transmits a high percentage of
blue light that is within a blue predetermined angle of incidence
range, (ii) reflects a high percentage of blue light that is
outside the blue predetermined angle of incidence range, (iii)
reflects a high percentage of green light, and (iv) reflects a high
percentage of red light.
[0011] Moreover, the light source assembly can include a green pass
filter that is positioned between the green LED and the pipe
passageway. The green pass filter (i) transmits a high percentage
of green light that is within a green predetermined angle of
incidence range, (ii) reflects a high percentage of green light
that is outside the green predetermined angle of incidence range,
and (iii) reflects a high percentage of red light.
[0012] The light source assembly can also include a blue dichroic
filter and/or a green dichroic filter positioned in the pipe
passageway. The blue dichroic filter (i) transmits a high
percentage of red light and green light, and (ii) reflects a high
percentage of blue light. The green dichroic filter (i) transmits a
high percentage of red light, and (ii) reflects a high percentage
of green light.
[0013] In one embodiment, (i) the first light source directs the
first light into the pipe passageway transverse to a passageway
axis of the pipe passageway, and/or (ii) the second light source
directs the second light into the pipe passageway transverse to the
passageway axis of the pipe passageway. In one embodiment, the
first light and the second light are directed into the pipe
passageway at an angle that is approximately 90 degrees relative to
the passageway axis.
[0014] Additionally, the present invention is directed to a light
source assembly that includes (i) an optical pipe that defines a
pipe passageway; (ii) a red LED that generates a red light that is
directed into the pipe passageway at a first region; (iii) a green
LED that generates a green light that is directed into the pipe
passageway at a second region that is different than the first
region; (iv) a green pass filter positioned between the green LED
and the pipe passageway, the green pass filter (a) transmitting a
high percentage of green light that is within a green predetermined
angle of incidence range, (b) reflecting a high percentage of green
light that is outside the green predetermined angle of incidence
range, and (c) reflecting a high percentage of red light; (v) a
blue LED that generates a blue light that is directed into the pipe
passageway at a third region that is different than the first
region and the second region; and (vi) a blue pass filter
positioned between the blue LED and the pipe passageway, the blue
pass filter (a) transmitting a high percentage of blue light that
is within a blue predetermined angle of incidence range, (b)
reflecting a high percentage of blue light that is outside the blue
predetermined angle of incidence range, (c) reflecting a high
percentage of green light, and (d) reflecting a high percentage of
red light.
[0015] The present invention is also directed to a method for
generating a homogenized light beam for a precision apparatus. The
method can include the steps of (i) generating a first light with a
first light source; (ii) generating a second light with a second
light source; and (iii) homogenizing the first light and the second
light with an optical pipe that defines a pipe passageway. In this
embodiment, the first light is directed into the pipe passageway at
a first region, and the second light is directed into the pipe
passageway at a second location that is different than the first
region.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic illustration of a light injection port
subassembly in accordance with certain exemplary embodiments of the
present disclosure;
[0017] FIG. 2 is a schematic illustration of a light source
assembly in accordance with certain exemplary embodiments of the
present disclosure, employing injection port filters, optionally
referred to here in some instances as Z-filters, for selected light
injection ports, together with dichroic filters optically
interposed between axially spaced light injection ports;
[0018] FIG. 3 is a schematic illustration of a light source
assembly in accordance with an alternative exemplary embodiment of
the present disclosure, employing dual injection port Z-filters for
selected light injection ports, together with dichroic filters
optically interposed between axially spaced light injection
ports;
[0019] FIG. 4 is a schematic illustration of an alternative
embodiment of a light source assembly in accordance with the
present disclosure, wherein the injection ports are sequenced
differently with respect to wavelength or color of the injected
light;
[0020] FIG. 5 is a schematic illustration of an alternative
embodiment of a light source assembly in accordance with the
present disclosure, wherein the injection ports are sequenced
differently with respect to wavelength of the injected light;
[0021] FIGS. 6-8 show plan, elevation and end views, respectively,
of a light source assembly in accordance with certain exemplary
embodiments of the present disclosure;
[0022] FIG. 9 is a schematic illustration of an alternative
embodiment of a light source assembly in accordance with the
present disclosure, employing dual injection port Z-filters for a
light injection port, along with recirculation stubs, together with
a dichroic filter optically interposed between axially spaced light
injection ports;
[0023] FIG. 10 is a graphical representation of LED energy angular
displacement in an exemplary embodiment of a light source assembly
in accordance with the present disclosure;
[0024] FIGS. 11 and 12 are schematic perspective views of an
exemplary embodiment of a light source assembly in accordance with
the present disclosure;
[0025] FIG. 13 is a single color or single wavelength light pipe in
accordance with an exemplary embodiment of the present
disclosure;
[0026] FIG. 14 is a single color or single wavelength light pipe in
accordance with an exemplary embodiment of the present disclosure,
employing recirculation stubs in the light injection port
subassembly;
[0027] FIG. 15. is a single color or single wavelength light pipe
in accordance with an exemplary embodiment of the present
disclosure, employing a light pipe having an expanding or enlarging
cross-sectional size in the downstream direction.
[0028] FIG. 16 is a simplified perspective illustration of a
precision apparatus having features of the present invention;
[0029] FIG. 17A is a perspective view of a light source assembly
having features of the present invention;
[0030] FIG. 17B is a cut-away view of the light source assembly of
FIG. 17A;
[0031] FIG. 18 is a cut-away view of another embodiment of a light
source assembly having features of the present invention;
[0032] FIG. 19 is a cut-away view of yet another embodiment of a
light source assembly having features of the present invention;
[0033] FIG. 20 is a cut-away view of still another embodiment of a
light source assembly having features of the present invention;
[0034] FIG. 21 is a cut-away view of another embodiment of a light
source assembly having features of the present invention;
[0035] FIG. 22 is a cut-away view of yet another embodiment of a
light source assembly having features of the present invention;
[0036] FIGS. 23A and 23B are alternative graphs that illustrate the
properties of alternative pass filters having features of the
present invention; and
[0037] FIG. 24 is a chart that lists the layer of materials for
making a filter having features of the present invention.
DETAILED DESCRIPTION OF CERTAIN EXEMPLARY EMBODIMENTS
[0038] The following detailed description of certain exemplary
embodiments is not intended to limit the scope of the disclosure to
merely those exemplary embodiments, but rather to be illustrative
of such scope. It will be apparent to those of ordinary skill in
the art that various different embodiments of the light source
assemblies disclosed here are suitable to be adapted for use in
innumerable video projection and display applications and the like.
Advantageously, for example, at least certain embodiments of the
light source assemblies disclosed here are suitable to have 3, 4, 5
or even more light injection ports.
[0039] In certain exemplary embodiments of the light source
assemblies disclosed here, multiple light sources are arranged to
feed light of different colors or wavelengths into a light pipe
operative to homogenize the light. The different color light
sources feed into the light pipe at spaced locations, with dichroic
filters being positioned diagonally across the light path in the
light pipe at correspondingly spaced locations. Dichroic filters
and angle-dependent, wavelength selective pass filters (or
"Z-filters"), described further below, control the flow of light
into and through the light pipe from at least selected light
sources associated with the light pipe. In certain exemplary
embodiments a light pipe assembly has dual angle-dependent,
wavelength-selective pass filters for one or more of the multiple
light sources, that is, both a horizontal angle-dependent,
wavelength-selective pass filter and a vertical angle-dependent,
wavelength-selective pass filter associated with a light injection
port feeding a particular light color into the light pipe. As
illustrated below, the angle-dependent, wavelength-selective pass
filters of the light pipes and light source assemblies disclosed
here pass the associated or corresponding wavelength range at
certain angles of incidence and reflect at other angles. Each of
the dichroic filters passes color(s) from any light source which is
upstream of that filter and reflects color(s) fed downstream of it.
Certain exemplary embodiments employ a single or mono
angle-dependent, wavelength-selective pass filter at a feed or
color injection port, and such angle-dependent,
wavelength-selective pass filter is not reflective of any color(s)
fed into the light pipe downstream of that filter. As illustrated
below, in certain exemplary embodiments of the light pipe
assemblies disclosed here, the angle-dependent,
wavelength-selective pass filters pass wavelength ranges different
from each other, rather than all passing the full spectrum of
wavelengths handled by the light pipe. Substantial cost savings can
be achieved in the design and production of such sequentially
varying, angle-dependent pass filters as compared to a set of
filters all operative to pass the full spectrum of wavelengths.
[0040] The angle-dependent, wavelength-selective pass filters are
etendue preserving or contribute to the etendue preserving
characteristics of the assembly, particularly in combination with
the dichroic filters of the light assemblies. The filters can be
short wave pass filters in certain embodiments, and in certain
embodiments can serve to increase the efficiency of the light pipe
assembly. The filters typically, including those shown in the
illustrated embodiments discussed below, are transmissive at least
of the color fed by the associated light source within a low angle
of incidence range, e.g., 0.degree.-30.degree.. Thus, each such
angle-dependent, wavelength-selective pass filter is transmissive
at the angle at which light is initially fed into the light pipe
through that filter from the associated light source. The filter is
reflective of those same wavelengths from the associated light
source within a high angle of incidence range, e.g.,
60.degree.-90.degree.. Also, the filter is reflective of other
colors fed into the light pipe, at least from upstream light
sources and at least within the high angle of incidence range,
e.g., 60.degree.-90.degree.. The angle-dependent,
wavelength-selective pass filters described here can be, but need
not be reflective of other colors, i.e., any colors fed into the
light pipe downstream of that filter. Likewise, such filters can
be, but need not be reflective of any of the colors at the
mid-range of angles of incidence.
[0041] In that respect, at least for applications in which the
human eye is the ultimate detector, such as a video display, an
advantageous order of the LED colors, i.e., of the light injection
ports into the light pipe, has been found to be (from the rear of
the unit to the front, where the front is the end at which light
exits the pipe in a combined or homogenized condition) is red,
green, blue. Such sequence is found to facilitate filter design. In
particular, for example, certain embodiments of the light source
assemblies disclosed here, having a red, green, blue sequence from
back to front facilitates horizontal angle-dependent,
wavelength-selective pass filter designs more readily produced
using current commercial filter production equipment and
techniques. Other color sequences also are found to be advantageous
in at least certain embodiments. The sequence blue, green, red
facilitates vertical filter designs more readily produced using
current commercial filter production equipment and techniques. The
sequence green, blue, red involves injecting the green color light
at the beginning, that is, at the back of the light pipe, and may
provide in at least certain exemplary embodiments, better overall
efficiency. For applications in which the absolute number of
photons (optical power) is more important, an advantageous order
may be different. The human eye sensitivity drives the previous
scenario (i.e., the eye is not as sensitive to blue as it is to
green, but the raw number of photons drives the desired balance in
other instrumentation. In that case, blue may more advantageously
be positioned at the back, because blue LEDs are efficient. Without
wishing to be bound by theory, it currently is understood that
there is more photonic energy in blue LED light output than in the
green or red portions of the spectrum.
[0042] In certain embodiments high index filters are used for the
dichroic filters and are advantageously found to be less sensitive
to angle of incidence. For example, filters having an index of
refraction n greater than 1.9, an even greater than 2.0 are within
the design capability of those skilled in the art given the benefit
of this disclosure.
[0043] A collimator optionally is employed with one or more, e.g.,
each, of the light sources. Also within the scope of this
disclosure are various alternative sequences of the light sources
(e.g., green/blue/red, etc.), as further presented below. In
certain exemplary embodiments of the light source assemblies
disclosed here, at least one of the tapered light collectors
comprises a tapered hollow light pipe or a solid-body molded
plastic light pipe. The tapered light collector is "operative to
reduce the angular distribution of the first color light entering
the light pipe from the first light source" means that it, at
least, results in the angular distribution of the light is smaller
or tighter or similarly improved in contrast to the angular
distribution which would result from the same configuration
(position, sizes, etc.) of the light pipe and light source(s)
without the tapered collimator.
[0044] Referring now to the drawings, the arrangement of FIG. 1
shows an LED 30 (blue in the illustration, but optionally any other
color/wavelength) with an associated light collector 31, e.g., a
lens and/or a tapered secondary (or feeder) light pipe, etc., to
collect the light output of the LED and pass it through an
angle-dependent, wavelength-selective pass filter 32, optionally
here referred to as a Z-filter or a feed filter, to the light pipe,
i.e., to the main or primary light pipe wherein multiple light
colors are passed along a common light path. The LED feed filter,
optionally referred to as a horizontal filter (notwithstanding that
it is shown in a vertical position in FIG. 1) in view of its
orientation substantially normal to the longitudinal axis of the
light path from the LED to the filter, can be in certain exemplary
embodiments a short wave pass filter operative to pass low angle
light rays, i.e., light impinging on the filter at low angles of
incidence, e.g., at least light incident at an angle within the
range of 0-30.degree., and further operative to pass high angle
light rays, i.e., light hitting the surface of the filter at a high
angle of incidence, e.g., at least light incident at an angle that
is near normal to the plane of the filter surface, e.g., within the
range of 60-90.degree.. The light pipe filter 33 oriented
diagonally to the longitudinal axis of the light path from the LED
to the angle-dependent, wavelength-selective pass filter, can be in
certain exemplary embodiments be reflective of all LED feed colors
to be passed along the common light path of the light pipe.
Alternatively, as discussed further below, especially in
embodiments of the light pipe assemblies disclosed here wherein one
or more LED feeds are upstream of the one feed shown in FIG. 1, the
diagonal filter can be operative to pass such upstream colors or,
in certain exemplary embodiments, to pass such upstream colors
which are incident at a high angle, e.g., at least light incident
at an angle within the range of 60-90.degree.. Thus, the diagonal
filter in such exemplary embodiments would pass at least light
traveling generally axially along the primary light path in the
light pipe.
[0045] FIG. 2 shows a light pipe design employing single Z-filters
for each downstream LED light feed, i.e., for the green and blue
LEDs in the illustrated embodiment. The light pipe design of FIG. 2
comprises red, green and blue LED feeds 34, 35, 36, in that order
from upstream to downstream, into the light pipe 37. The red LED
emits red light into the light pipe via a lens system or the like,
such as a tapered feeder light pipe 38. The green and blue LEDs
each likewise emits light into the light pipe via a tapered feeder
light pipe, lens, etc., 39, 40. The dichroic filter 41 for the
green LED, oriented diagonally to the common light path 42 of the
light pipe, i.e., to its primary axial light path, passes red light
from the red LED, which is seen to be upstream of the green LED,
and reflects green light. The dichroic filter for the blue LED
passes red light from the red LED and green light from the green
LED, both of which are upstream of the blue LED, and reflects blue
light. The horizontal LED feed filters 44, 45 can be short wave
pass filters in accordance with the operating principles discussed
above for the horizontal blue LED feed filter discussed above in
connection with the embodiment of FIG. 1. Thus, the green and blue
Z-filters in embodiments consistent with FIG. 2 can be operative to
pass low angle light rays, e.g., at least light incident at an
angle within the range of 0-30.degree., and further operative to
pass high angle light rays, e.g., at least light incident at an
angle that is near normal to the plane of the filter surface, e.g.,
within the range of 60.degree.-90.degree.. At least certain
embodiments of the light pipe assemblies disclosed here, including,
for example, those in accordance with the assembly illustrated in
FIG. 2, having such reflectivity and light transmission properties,
are etendue preserving such that light is passed from the light
pipe at the downstream outlet of the light pipe as F1 output at
60.degree.-90.degree.. In the illustrated embodiment of FIG. 2, no
light filter is employed for the red LED, although those skilled in
the art will appreciate, given the benefit of this disclosure, that
a filter, lens, etc. may optionally be employed.
[0046] FIG. 3 shows a dual filter design, i.e., a design with dual
angle-dependent, wavelength-selective pass filters at one or more
light input ports, for a light pipe having red, green, and blue LED
light sources 46, 47, 48, in that order from upstream to
downstream. Each horizontal angle-dependent, wavelength-selective
pass filter is simply a short wave pass filter. Each vertical
angle-dependent, wavelength-selective pass filter 49, 50 is
operative to pass two colors or three colors. Specifically, the
vertical z-filter 51 for the green LED passes red light and passes
green light at high angles of incidence. It reflects green light at
low angles of incidence. The vertical z-filter 52 for the blue LED
is optional and passes red light and green light, as well as blue
light at high angles of incidence. It reflects blue light at low
angles of incidence. In embodiments of the light pipe assemblies
disclosed here which are consistent with FIG. 3, a light filter at
the injection port for the red LED may be employed but is optional.
Thus, those skilled in the art will appreciate, given the benefit
of this disclosure, that a filter, lens, etc. may optionally be
added for the red LED in the assembly illustrated in FIG. 3. At
least certain embodiments having the reflectivity properties
mentioned above provide light output at the downstream (right side
in FIG. 3) output of the light pipe as F1 light output at
60.degree.-90.degree..
[0047] FIG. 4 shows a dual filter design for a light pipe having a
blue, green, red LED sequence. Each horizontal angle-dependent,
wavelength-selective pass filter 53, 54, i.e., the filters
positioned at a color's injection port into the light pipe (i.e.,
into the primary light pipe) passes the injected color, at least at
high angles of incidence, and reflects the upstream colors. In at
least certain exemplary embodiments the horizontal filter 53 for
the green LED reflects blue light, at least at high angles of
incidence, reflects green light at low angles of incidence, and
passes green light at high angles of incidence, e.g.,
60.degree.-90.degree., such as light directly from the green LED
along the longitudinal axis of the light main light path from the
green LED to the associated horizontal filter. The horizontal
filter 54 for the red LED passes red light at high angles of
incidence, reflects red light at low angles of incidence, and
reflects green and blue light at least at high angles of incidence.
The green LED and the red LED each also has a vertical
angle-dependent, wavelength-selective pass filter. The vertical
filter 55 associated with the green LED and the vertical filter 56
associated with the red LED, which are positioned in the light pipe
and oriented substantially perpendicular or normal to the primary
light path 57 of the light pipe, each can be provided as a short
wave pass filter operative to pass the upstream colors incident on
the filter, at least at a large angle of incidence, e.g., at
60.degree.-90.degree..
[0048] FIG. 5 shows a mono-filter design, an angle-dependent,
wavelength-selective pass filter design for a green, blue, red LED
injection sequence. Each horizontal angle-dependent,
wavelength-selective pass filter is a short wave pass filter. The
horizontal z-filter 58 for the blue LED 60 passes blue light at
high angles of incidence and reflects blue light at low angles of
incidence. Further, it is operative to reflect green light from the
upstream green LED at least at high angles of incidence. The red
LED's 61 horizontal angle-dependent, wavelength-selective pass
filter 59 is operative to pass red light from the associated red
LED and to reflect blue and green light emitted by the upstream
LEDs and passed downstream along the light path of the light pipe.
In certain alternative embodiments otherwise consistent with the
illustrated embodiment of FIG. 5, red LED's horizontal
angle-dependent, wavelength-selective pass filter is omitted, as it
has been determined and that substantial cost savings can be
thereby achieved with only small loss of red light throughput,
e.g., approximately 5% or less reduction in red light efficiency
for the overall light pipe assembly. Further in this regard, the
upstream/downstream positions of the red and blue LEDs can be
reversed in alternative embodiments. In such alternative
embodiments, the horizontal angle-dependent, wavelength-selective
pass filter for the blue LED can be omitted on the same principles
discussed immediately above with respect to omitting the red LED
horizontal angle-dependent, wavelength-selective pass filter in the
illustrated embodiment of FIG. 5. In the illustrated embodiment of
FIG. 5, no light filter is employed for the upstream green LED,
although those skilled in the art will appreciate, given the
benefit of this disclosure, that a filter, lens, etc. may
optionally be employed. At least certain exemplary embodiments of
the light pipe assemblies disclosed here comprise for the various
LEDs associated etendue preserving structure for passing light into
the light pipe, e.g., a lens system or the like, such as a tapered
feeder light pipe.
[0049] Light pipe assembly dimensions for certain exemplary
embodiments in accordance with the present disclosure are shown in
FIGS. 6-8. The overall length of the light pipe 62 is 65 mm,
including a tapered portion at the upstream (left-hand side in FIG.
6) suitable for use as an axial-end injection port, i.e., an
injection port for a first LED. The lateral dimension of the main
light pipe, that is, its outside cross-sectional dimension, is 8.2
mm by 6.15 mm. The inside dimension is 6.0 mm by 4.5 mm. For ease
of construction, the light pipe may be constructed with flat
sidewalls in a square or other rectangular cross-sectional
figuration. Each of the two side injection ports for additional
LEDs has an outside axial dimension (i.e., a dimension measured
along the longitudinal direction of the main light pipe) of about
8.2 mm at its largest point where it joins the main light pipe, and
a lateral dimension of about 5.0 mm. The tapered light pipes of the
LED injection ports have an inside axial dimension (i.e., a
dimension measured along the longitudinal direction of the main
light pipe) tapering from 6.06 mm to 3.81 mm. The second (i.e.,
middle) LED injection port is 7.5 mm from the axial-end injection
port. The third (i.e., left-most) LED injection port axially
overlaps the second LED injection port by approximately 0.6 mm.
While this configuration and these dimensions have been found to be
advantageous for at least certain exemplary embodiments of light
pipe assemblies in accordance with this disclosure, those of
ordinary skill in the art, given the benefit of this disclosure,
will recognize that innumerable alternative configurations and
dimensions are possible for other embodiments of the light pipes
disclosed here.
[0050] FIG. 9 illustrates an alternative embodiment of the light
pipe assemblies disclosed here. As seen in FIG. 9, the red LED
injection port 63 is upstream of the green LED injection port 64.
The red LED is axially in line with the main output port 65 of the
light pipe. A dichroic filter 66 oriented diagonally across the
axial light path 67 from the red LED to the main output port passes
red light emitted by the red LED and reflects green light emitted
by the green LED. The green LED injection port is at a side wall 68
of the light pipe 69. The horizontal angle-dependent,
wavelength-selective pass filter 70 for the green LED, which is
positioned in-line with the side wall 68 of the main light pipe
(and is oriented vertically in the illustration of FIG. 9) reflects
light above 60.degree. and passes might below 60.degree.. The
second angle-dependent, wavelength-selective pass filter 71 passes
the red and green lights. The red LED being at the most upstream of
the injection ports simplifies the filter design for embodiments in
accordance with FIG. 9. Those of ordinary skill in the art will
recognize, however, that alternative sequences are possible for the
LEDs without departing from the principles disclosed here.
[0051] The embodiment of FIG. 9 also illustrates an optional
feature of the light pipe assemblies disclosed here. Specifically,
stubs 72a, 72b are provided at the periphery of the green LED's
horizontal angle-dependent, wavelength-selective pass filter. Such
stubs may be used for any or all of the LED injection ports. The
stubs provide certain degree of light recirculation within the
injection port sub-assembly 73 and rely upon the LED's surface
being somewhat reflective. Improved efficiency can be achieved
through the use of such stubs in at least certain embodiments of
the light pipe assemblies disclosed here.
[0052] FIGS. 11 and 12 are perspective views, from different
angles, of one embodiment 74 of a light pipe assembly in accordance
with the present disclosure. The light pipe assembly of FIGS. 11
and 12 has 3 light injection ports, including an axial injection
port 75 at the upstream end and two lateral injection ports 76, 77.
In this regard, it should be understood that any of the features
discussed or disclosed here for any injection port may be used in
any permutation or combination with any other such disclosed
injection port feature(s). Likewise, any other light pipe features
discussed or disclose here may be used in any combination or
permutation with any other such discussed or disclosed features.
Typically, but not necessarily in all embodiments, a different
light color will be injected at each of the three ports, four total
of three different colors. The light may be emitted by associated
LEDs or other suitable light sources. Blue, green and red light
sources may be used, for example, in any order or sequence.
[0053] FIGS. 13 and 14 illustrate alternative embodiments of a
single color or single wavelength light pipe in accordance with the
present disclosure. FIG. 13 illustrates a single color light pipe
embodiment 78 in accordance with the present disclosure. An axial
injection port 79 comprises an LED light source 80 and an
associated tapered feeder light pipe 81. The LED 82 itself in
certain exemplary embodiments is sufficiently reflective to provide
a useful level of recirculation of the emitted light. Light emitted
by the LED light source passes into the light pipe 83 through an
angle-dependent, wavelength-selective pass filter 84, that is,
through a filter which passes the emitted light at high angles of
incidence, e.g., 60.degree.-90.degree., and reflects such light at
small angles of incidence, e.g., 0.degree.-30.degree.. Optionally,
the angle-dependent, wavelength-selective pass filter can be
positioned further downstream, typically, but not necessarily,
retaining its orientation in a plane substantially normal to the
longitudinal axis of light pipe. The light output of the light pipe
is unpolarized, although a polarizer could be used instead of, or
in series with, the angle-dependent, wavelength-selective pass
filter. For example, a polarizer filter could be positioned at the
outlet port 85 of the light pipe (that is, at the extreme right end
of the light pipe, as shown in FIG. 13), typically, but not
necessarily, being oriented in a plane normal to the longitudinal
axis of the light pipe.
[0054] FIG. 14 illustrates an alternative single color light pipe
embodiment in accordance with the present disclosure. An axial
injection port 86 comprises an LED light source and an associated
tapered feeder light pipe 88. The LED itself in certain exemplary
embodiments is sufficiently reflective to provide a useful level of
recirculation of the emitted light. The feeder light pipe also
employs stubs 89, 90 in the injection port sub-assembly 86 for
recirculation and etendue improvement. Light emitted by the LED
light source passes into the light pipe through an angle-dependent,
wavelength-selective pass filter 91, that is, through a filter
which passes the emitted light at high angles of incidence, e.g.,
60.degree.-90.degree., and reflects such light at small angles of
incidence, e.g., 0.degree.-30.degree.. The light output of the
light pipe is unpolarized, although a polarizer could be used
instead of, or in series with, the angle-dependent,
wavelength-selective pass filter.
[0055] FIG. 15 illustrates a single color light pipe embodiment 92
in accordance with the present disclosure, having F2.4 light
output. The light pipe 93 can be seen to be tapered, having an
inside cross-sectional size which becomes larger toward the output
port 94 of the light pipe. An axial injection port 95 comprises an
LED light source 96 and an associated tapered feeder light pipe 97.
As in other embodiments disclosed and discussed here, the lens
system for collecting and passing light from the LED or other light
source into the light pipe, may comprise a TIR, one or more lenses,
a straight-wall or tapered light pipe or the like any combination
of them. Optionally, stubs are employed in the injection port
subassembly to provide recirculation for improved etendue. The LED
itself in certain exemplary embodiments is sufficiently reflective
to provide a useful level of recirculation of the emitted light.
Light emitted by the LED light source passes into the light pipe
through a angle-dependent, wavelength-selective pass filter 98,
that is, through a filter which passes the emitted light at high
angles of incidence, e.g., 60.degree.-90.degree., and reflects such
light at small angles of incidence, e.g., 0.degree.-30.degree..
Optionally, the angle-dependent, wavelength-selective pass filter
can be positioned further downstream, typically, but not
necessarily, retaining its orientation in a plane substantially
normal to the longitudinal axis of light pipe. The light output of
the light pipe is unpolarized, although a polarizer could be used
instead of, or in series with, the angle-dependent,
wavelength-selective pass filter. For example, a polarizer filter
could be positioned at the outlet port of the light pipe (that is,
at the extreme right end of the light pipe, as shown in FIG. 13),
typically, but not necessarily, being oriented in a plane normal to
the longitudinal axis of the light pipe.
[0056] As seen in many illustrated embodiments discussed above, at
least one of the light injection ports may comprise a tapered light
collector, which may in turn comprise a hollow light pipe fixedly
integrated with the light pipe. In certain exemplary embodiments
the light source assembly may employ a short wave pass filter as a
horizontal angle-dependent, wavelength-selective pass filter
positioned at the light entrance port into the light pipe. In
certain embodiments the light source assembly a dichroic filter is
positioned in the light pipe at a 30.degree. to 60.degree. angle to
the axial optical pathway.
[0057] Certain embodiments of the light source assembly have a
second light injection port or entrance located axially along the
light pipe between the first light entrance or port and a third
light port. The light source assembly further comprises a primary
entrance filter positioned at the second light entrance in a plane
generally parallel to the elongate axial optical pathway. The
second light entrance filter is operative: [0058] a. to pass at
least a second color light having an angle of incidence of from
0.degree. to 30.degree. upon the primary second light entrance
filter, and [0059] b. to reflect at least [0060] i. the second
color light having an angle of incidence of from 60.degree. to
90.degree. upon the primary second light entrance filter, and
[0061] ii. first color light having an angle of incidence of from
0.degree. to 30.degree. upon the primary second light entrance
filter.
[0062] The light source assembly of certain embodiments further
comprises reflective surface area at the perimeter of at least one
of the light entrances, which reflective surface areas are
operative to provide recirculation of at least a portion of the
light from the associated light source. Optionally, the second
light collector increases in size toward an opening at the second
light entrance into the light pipe, the opening of the light
collector is larger than the second light entrance, and the
reflective surface at the perimeter of the second light entrance is
operative to reflect back at least a portion of the light from the
second light source which does not pass through the primary second
light entrance filter. In certain embodiments the light emitter is
an LED, LCD or the like, which is itself somewhat reflective of the
light it is emitting. The light source assemblies optionally
further comprise a secondary second light entrance filter
positioned in the axial optical pathway and optically between the
second light entrance and the light port. The secondary second
light entrance filter is operative to pass at least [0063] first
color light having an angle of 0.degree. to 30.degree. to the axial
optical pathway to the light port, and [0064] second color light
having an angle of 0.degree. to 30.degree. to the axial optical
pathway to the light port.
[0065] The secondary second light entrance filter is also operative
in certain such embodiments to reflect at least second color light
having an angle of 60.degree. to 90.degree. to the axial optical
pathway to the light port.
[0066] In accordance with another aspect, a light source assembly
further comprises at least one light valve positioned to receive
light passed from the light pipe via the light port (i.e., at the
front or output end), and at least one focusing relay lens
positioned between the light port and the light valve and operative
to focus light passed from the light pipe via the light port to the
light valve.
[0067] Certain exemplary embodiments of the light source assemblies
disclosed here further comprise a third tapered light collector at
a third light entrance to the light pipe. Such third light entrance
can be axially spaced from the first and second light entrances and
located between the second light entrance and the optical port
(i.e., output port of the light pipe). A third light source is
operative to generate a third color light, different from the first
and second color lights, into the light pipe via the third tapered
light collector. The third tapered light collector is operative to
reduce the angular distribution of the third color light entering
the light pipe from the third light source. At least a second
dichroic filter is positioned in the axial optical pathway
optically between the second light entrance and the third light
entrance, the second dichroic filter being operative to pass first
and second color light from the first and second light sources,
respectively, toward the light port and to reflect third color
light from the third light source toward the light port. The light
pipe is operative to homogenize the first, second and third color
lights passed simultaneously into the light pipe from the first,
second and third light sources, respectively. In certain exemplary
embodiments such light source assemblies, the second dichroic
filter is positioned in the light pipe at a 30.degree. to
60.degree. angle to the axial optical pathway.
[0068] Optionally such light source assemblies further comprise a
primary second light entrance filter positioned at the second light
entrance and a primary third light entrance filter positioned at
the third light entrance in a plane generally parallel to the axial
optical pathway. The primary second light entrance filter is
positioned at the second light entrance in a plane generally
parallel to the axial optical pathway. It is operative to pass at
least second color light having an angle of incidence of from
0.degree. to 30.degree. upon the primary second light entrance
filter, and to reflect at least second color light having an angle
of incidence of from 60.degree. to 90.degree. upon the primary
second light entrance filter, and first color light having an angle
of incidence of from 0.degree. to 30.degree. upon the primary
second light entrance filter. The primary third light entrance
filter can be positioned at the third light entrance in a plane
generally parallel to the axial optical pathway. It is operative to
pass at least second color light having an angle of incidence of
from 0.degree. to 30.degree. upon the primary second light entrance
filter, and to reflect at least second color light having an angle
of incidence of from 60.degree. to 90.degree. upon the primary
second light entrance filter, and first color light having an angle
of incidence of from 0.degree. to 30.degree. upon the primary
second light entrance filter.
[0069] As noted above, the light source assembly may comprise a
light pipe comprising a hollow elongate rectangular pipe segment
extending from a first axial end of the rectangular pipe segment to
the light port at a second axial end of the rectangular pipe
segment. The first light entrance in certain exemplary embodiments
is an axial entrance at the first axial end of the rectangular pipe
segment, and the second light entrance is a lateral entrance
through a side wall of the rectangular pipe segment. The third
light entrance optionally is a lateral entrance through a side wall
of the rectangular pipe segment. In some advantageous embodiments,
the first light source comprises a green LED, the second light
source comprises a blue LED, and the third light source comprises a
red LED. In alternative embodiments the light source assembly has a
green LED.
[0070] In certain exemplary embodiments of the light source
assemblies disclosed here, at least one of the first and second
tapered light collectors is an anamorphic collector or a focusing
light collector operative to focus light from the associated light
source into the light pipe. The light source assembly may employ a
non-focusing light collector for at least one of the first and
second tapered light collectors.
[0071] In certain exemplary embodiments of the light source
assemblies disclosed here, the first dichroic filter comprises a
thin film filter.
[0072] In accordance with certain exemplary embodiments, a light
source assembly comprises, in combination:
[0073] an light pipe forming at least a light port and an elongate
axial optical pathway to the light port;
[0074] a first tapered light collector;
[0075] a first light source operative to generate a first color
light into the light pipe at a first light entrance via the first
tapered light collector, the first tapered light collector being
operative to reduce the angular distribution of the first color
light entering the light pipe from the first light source;
[0076] a second tapered light collector;
[0077] a second light source operative to generate a second color
light, different from the first color light, into the light pipe
via the second tapered light collector at a second light entrance
axially spaced from the first light entrance, the second tapered
light collector being operative to reduce the angular distribution
of the second color light entering the light pipe from the second
light source; and
[0078] at least a first dichroic filter positioned in the light
pipe optically between the first and second light entrances and
operative as oriented in the light pipe
[0079] to pass first color light from the first light source toward
the light port, and
[0080] to reflect second color light from the second light source
toward the light port;
[0081] wherein the light pipe is operative to homogenize the first
and second color lights passed simultaneously to the light port
from the first and second light sources, respectively.
[0082] The light source assemblies disclosed here are applicable to
numerous different fields of use and to different applications
within a field of use. Such different fields of use include medical
applications for the light source assemblies, including, for
example, spectroscopic (UV fluorescence) applications, e.g.,
medical diagnostics, environmental testing, chemical testing and
processing, security detection, etc.
[0083] Referring initially to FIG. 16, the present invention is
directed to a precision apparatus 110 that, for example, can be
used as or in optical communications, light projection systems,
scientific instruments and manufacturing equipment. FIG. 16 is a
simplified, non-exclusive, perspective view of one embodiment of
the precision apparatus 110. In this embodiment, the precision
apparatus 110 is a light projection system, commonly referred to as
a Digital Mirror Device ("DMD system"). Alternatively, for example,
the precision apparatus 110 can be another type of apparatus that
uses a light beam. For example, the present invention can be used
in another type of projection system such as a Liquid Crystal
Display (LCD) system or a Liquid Crystal on Silicon (LCOS)
system.
[0084] In FIG. 16, the precision apparatus 110 includes a light
source assembly 112, a mirror 114, an imager 116, a lens 118, and a
screen 120 that cooperate to generate an image 122 (represented as
an "X") on the screen 120. The design and orientation of the
components of the precision apparatus 110 can be changed to suit
the requirements of the precision apparatus 110. Further, the
precision apparatus 110 can be designed with fewer or more
components than those illustrated in FIG. 16.
[0085] The light source assembly 112 generates a light 124 for the
projection system 110. As an overview, in certain embodiments, the
light source assembly 112 generates a homogenized, incoherent
bright white light 124 that includes blue light, green light and
red light. As a result thereof, in certain embodiments, one or more
components, such as a color wheel is not required for the DMD
system. Further, in one embodiment, multiple light beams are
multiplexed in a light pipe. With this design, the light source
assembly 112 can be controlled to generate an output beam having
any desired color, including red, blue, green or white.
[0086] Moreover, in certain embodiments, the light source assembly
112 can be designed to efficiently generate the light 124 with
relatively low power. This reduces the amount of heat generated by
the light source assembly 112 and improves the performance of the
precision apparatus 110. Additionally, the light source assembly
112 has a relatively long operational lifespan, has good power
stability, and is relatively small in size.
[0087] The mirror 114 reflects the light 124 exiting from the light
source assembly 112 and directs the light 124 at the imager
116.
[0088] The imager 116 creates the image 122. In one embodiment, the
imager 116 is a digital light processing chip that includes
anywhere from approximately 800 to more than 1 million tiny mirrors
that are individually controlled to generate the image 122.
Alternatively, for example, the imager 122 can be a LCD imager or a
LCOS imager.
[0089] The lens 118 collects the image 122 from the imager 116 and
focuses the image 122 on the screen 120. The screen 120 displays
the image 122.
[0090] FIG. 17A is a perspective view and FIG. 17B is a cut-away
view of one embodiment a light source assembly 212 that can be used
in a precision apparatus 110 (illustrated in FIG. 16). In this
embodiment, the light source assembly 212 includes a plurality of
light sources 226, an optical pipe 228, and a director assembly
230.
[0091] The number and design of the light sources 226 can be varied
pursuant to the teachings provided herein. In one embodiment, the
light source assembly 212 includes three separate light sources
226, namely a blue light source 234 (illustrated as a box) that
generates blue light 234A (illustrated as an arrow), a green light
source 236 (illustrated as a box) that generates green light 236A
(illustrated as an arrow), and a red light source 238 (illustrated
as a box) that generates red light 238A (illustrated as an arrow).
The blue light 234A has a wavelength of between approximately
450-490 nm, the green light 236A has a wavelength of between
approximately 490-570 nm, and the red light 238A has a wavelength
of between approximately 630-700 nm. Alternatively, the light
source assembly 212 could be designed with greater than or fewer
than three light sources 236.
[0092] It should be noted that the blue light source 234, the green
light source 236, and/or the red light source 238 can be referred
to herein as the first light source, the second light source, or
the third light source. Further, the blue light 234A, the green
light 236A, and/or the red light 238A can be referred to herein as
the first light, the second light, or the third light.
[0093] In one embodiment, each of the light sources 226 is a light
emitting diode ("LED"). In this example, the blue light source 234
is a blue LED, the green light source 236 is a green LED, and the
red light source 238 is a red LED. In one non-exclusive embodiment,
the blue light source 234 has an output of between approximately
100 to 200 lumen, the green light source 236 has an output of
between approximately 900 to 1100 lumen, and the red light source
238 has an output of between approximately 300 to 500 lumen.
Alternatively, each of the light sources 234, 236, 238 can be
designed to have an output that is greater or lesser than the
amounts described above.
[0094] In one embodiment, each of light sources 234, 236, 238 is
turned on and off is sequence. As a result thereof, a color wheel
(not shown) may not be necessary for a DMD system. This allows for
a smaller form factor for the DMD system and can reduce the cost
for assembly of the DMD system. Moreover, the LED's have a
relatively long operational lifespan. Alternatively, the light
sources 234, 236, 238 can be maintained on and a color wheel can be
utilized. Further, the light sources 234, 236, 238 can be
controlled to generate an output light 224 having any desired
color, including red, blue, green or white.
[0095] The optical pipe 228 captures the lights 234A, 236A, 238A
and homogenizes the lights 234A, 236A, 238A so that the light 224
exiting the light source assembly 212 is uniform, consistent, and
has the desired aspect ratio. Optical pipes are also sometimes
referred to as light tunnels or tunnel integrators. The design of
the optical pipe 228 can be varied pursuant to the teachings
provided herein. FIGS. 17A and 17B illustrate a first embodiment of
the optical pipe 228. In this embodiment, the optical pipe 228 is
generally rectangular tube shaped and defines a generally
rectangular shaped pipe passageway 228A.
[0096] Further, in this embodiment, the pipe passageway 228A (i) is
substantially linear and includes a substantially linear passageway
axis 228L, (ii) does not include any bends, and (iii) the light
234A, 236A, 238A from the light sources 234, 236, 238 travel down
the same pipe passageway 228A. As a result of this design, in
certain embodiments, the profile of the light source assembly 212
can be relatively small. Alternatively, pipe passageway 228A can
include one or more bends. For Example, the pipe passageway 228A
can include one or more 90 degree bends.
[0097] In one embodiment, the optical pipe 228 includes a generally
rectangular tube shaped pipe body 228B and a wall coating 228C that
define the generally rectangular shaped pipe passageway 228A. The
pipe body 228B can include four walls 228D, with each of the walls
228D having an interior wall surface and an exterior wall surface.
The four walls 228D can be referred to as a top wall, a bottom
wall, a left wall, and a right wall for convenience. Alternatively,
for example, the pipe body 228B can have another configuration,
such as a circular shaped tube, an octagon shaped tube, or a
triangular shaped tube for example.
[0098] In one embodiment, the interior wall surfaces are coated
with the wall coating 228C. For example, the wall coating 228C can
have a relatively high reflectivity for the visible wavelength
range (approximately 400-750 nm). With this design, the wall
coating 228C inhibits the light 224 from exiting the pipe
passageway 228A and homogenizes the light 224. Suitable wall
coatings 228C can include dielectric materials and/or metal (silver
or aluminum) material.
[0099] The wall coating 228C may have to be applied with multiple
coating layers, and can be deposited using a number of different
methods including physical vapor deposition such as ion beam
sputtering, magnetron sputtering, and ion assisted evaporation. One
method for depositing a coating is disclosed in U.S. Pat. No.
6,736,943, the contents of which are incorporated herein by
reference.
[0100] Moreover, in this embodiment, the optical pipe 228 includes
(i) a leading edge 228E, (ii) an opposed trailing edge 228F
(sometimes referred to as the "output end") that faces the mirror
114 (illustrated in FIG. 16), (iii) a red region 228G, (iv) a green
region 228H, (v) a blue region 228I, and (vi) a homogenizing region
228J. The design and location of each of these regions 228B-228E
can be varied pursuant to the teachings provided herein.
[0101] The red light 238A is directed into the optical pipe 228 at
the red region 228G, the green light 236A is directed into the
optical pipe 228 at the green region 228H, and the blue light beam
234A is directed into the optical pipe 228 at the blue region 228I.
In FIGS. 17A and 17B, the red region 228G, the green region 228H,
and the blue region 228I is each generally rectangular tube shaped
and each includes a region aperture 228K (e.g. a port) that
receives a portion of the director assembly 230 and that extends
through the front wall 228D. Alternatively, one or more of these
regions 228G-228I can have another configuration. It should be
noted that the red region 228G, the green region 228H, and/or the
blue region 228I can be referred to herein as the first region, the
second region, or the third region. Further, the region apertures
228K are spaced apart And can be referred to as the first inlet
port, the second inlet port, the third inlet. Further, the region
aperture 228K in the red region 228G can be referred to as the red
inlet port, the region aperture 228K in the green region 228H can
be referred to as the green inlet port, and the region aperture
228K in the blue region 228I can be referred to as the blue inlet
port.
[0102] The homogenizing region 228J homogenizes the light 234A,
236A, 238A that travel down the pipe passageway 228A. In FIGS. 17A
and 17B, the homogenizing region 228J is generally tapered
rectangular tube shaped and the light 234A, 236A, 238A from each of
the sources travels down the same path. As a result thereof, the
light 224 is generally rectangular shaped. Alternatively, the
homogenizing region 228J can have another configuration to suit the
desired aspect ratio of the light beam 224.
[0103] In FIGS. 17A and 17B, the red region 228G, the green region
228H, the blue region 228I, and the homogenizing region 228J are
illustrated as a continuous piece. Alternatively, one or more of
these regions 228G-228J can be made separately and subsequently
attached to the other regions 228G-228J.
[0104] Moreover, in FIGS. 17A and 17B, moving from the leading edge
228E to the trailing edge 228F the regions are organized as the red
region 228G, the green region 228H, the blue region 228I, and the
homogenizing region 228J. In this embodiment, moving from the
leading edge 228E to the trailing edge 228F, the regions 228G,
228H, 228I are organized so that the longest wavelength light
enters the pipe passageway 238A closest to the leading edge 228E
and the shortest wavelength light enters the pipe passageway 238A
closest to the trailing edge 228F. Stated in another fashion,
moving from the leading edge 228E to the trailing edge 228F, the
light sources 234, 236, 238 are organized so that the light enters
the pipe passageway 238A from longest wavelengths to the shortest
wavelengths. With this design, the red light 238A enters the pipe
passageway 238A closest to the leading edge 228E, the blue light
234A enters the pipe passageway 238A closest to the trailing edge
(exit) 228F, and the green light 236A enters the pipe passageway
238A intermediate where the red light 238A and the blue light 234A
enters the pipe passageway 238A. This simplifies the design of one
or more of the filters of the director assembly 230. Alternatively,
the orientation of the red region 228G, the green region 228H, and
the blue region 228I can be different than that illustrated in the
Figures.
[0105] The director assembly 230 allows the desired light to enter
the pipe passageway 228A and directs the desired light down the
pipe passageway 228A. The design of the director assembly 230 can
vary pursuant to the teachings provided herein. In FIGS. 17A and
17B, the director assembly 230 includes (i) a red pass filter 240,
(ii) an end reflector 242, (iii) a green pass filter 244, (iv) a
green Dichroic filter 246, (v) a blue pass filter 248, and (vi) a
blue Dichroic filter 250. Alternatively, the director assembly 230
could be designed to have more components or fewer components than
those illustrated in FIGS. 17A and 17B.
[0106] It should be noted that the red pass filter 240, the green
pass filter 244, and/or the blue pass filter 248 can be referred to
as a first pass filter, a second pass filter, or a third pass
filter. These pass filters 240, 244, 248 keep light that has
entered the pipe passageway 228A in the pipe passageway 228A to
enhance the efficiency of the assembly. It should also be noted
that the green Dichroic filter 246 or the blue Dichroic filter 250
can be referred to as a first Dichroic filter or a second Dichroic
filter.
[0107] The red pass filter 240 is positioned between the red light
source 238 and the pipe passageway 228A, allows red light 238A from
the red light source 238 to enter the pipe passageway 228A, and
inhibits red light 238A in the pipe passageway 228A from exiting
via the red pass filter 240. In one embodiment, the red pass filter
240 is capable of (i) transmitting a high percentage of red light
that is within a red predetermined angle of incidence range, (ii)
reflecting a high percentage red light that is outside the red
predetermined angle of incidence range, (iii) reflecting a high
percentage of blue light, and (iv) reflecting a high percentage of
green light. In alternative, non-exclusive embodiments, the red
predetermined angle of incidence range is between approximately 0
to 50; 0 to 45; 0 to 30; 0 to 20; 0 to 10; or 0 to 5 degrees.
[0108] Further, in alternative, non-exclusive embodiments, the
phrase "transmitting a high percentage" shall mean an average
transmittance of greater than approximately 85, 90, 95, 96, 97, 98,
or 99. Moreover, in alternative, non-exclusive embodiments, phrase
"reflecting a high percentage" shall mean an average reflection of
greater than approximately 85, 90, 95, 96, 97, 98, or 99.
[0109] In FIGS. 17A and 17B, the red pass filter 240 is positioned
in the region aperture 228K in the wall 228D of the pipe body 228B
at the red region 228G. In one embodiment, the red pass filter 240
is generally rectangular plate shaped and fits into the rectangular
shaped region aperture 228K. Alternatively, the red pass filter 240
can have another configuration. As illustrated in FIG. 17B, in one
embodiment, the red light 238A is directed into the pipe passageway
228A substantially transverse to the passageway axis 228L of the
pipe passageway 228A. As used herein, the term transverse shall
mean at an angle relative to the passageway axis. For example, the
red light 238A can be directed into the pipe passageway 228A at an
angle of approximately 90 degrees relative to the passageway axis
228L. Alternatively, the red light 238A can be directed into the
pipe passageway 228L at angles other than 90 degrees.
[0110] The end reflector 242 reflects the red light 238A and
directs the red light 238A along the pipe passageway 228A. In FIGS.
17A and 17B, the end reflector 242 extends across the pipe
passageway 228A at an angle (e.g. approximately 45 degrees in one
embodiment) and reflects substantially all light that is within the
visible wavelengths towards the trailing edge 228E. Additionally,
the end reflector 242 is positioned at the edge of the red region
228G. In one embodiment, the end reflector 242 is generally
rectangular plate shaped and has a size and shape that corresponds
to that of the pipe passageway 228A.
[0111] The green pass filter 244 is positioned between the green
light source 236 and the pipe passageway 228A, allows green light
236A from the green light source 236 to enter the pipe passageway
228A, and inhibits green light 236A and red light 238A in the pipe
passageway 228A from exiting via the green pass filter 244. In one
embodiment, the green pass filter 244 is capable of (i)
transmitting a high percentage of green light that is within a
green predetermined angle of incidence range, (ii) reflecting a
high percentage green light that is outside the green predetermined
angle of incidence range, (iii) reflecting a high percentage of
blue light, and (iv) reflecting a high percentage of red light. In
alternative, non-exclusive embodiments, the green predetermined
angle of incidence range is between approximately 0 to 50; 0 to 45;
0 to 30; 0 to 20; 0 to 10; or 0 to 5 degrees.
[0112] In FIGS. 17A and 17B, the green pass filter 244 is
positioned in the region aperture 228K in the wall 228D of the pipe
body 228B at the green region 228H. In one embodiment, the green
pass filter 244 is generally rectangular plate shaped and fits into
the rectangular shaped region aperture 228K. Alternatively, the
green pass filter 244 can have another configuration. As
illustrated in FIG. 17B, in one embodiment, the green light 236A is
directed into the pipe passageway 228A substantially transverse to
the passageway axis 228L. For example, the green light 236A can be
directed into the pipe passageway 228A at an angle of approximately
90 degrees relative to the passageway axis 228L. Alternatively, the
green light 236A can be directed into the pipe passageway 228L at
angles other than 90 degrees.
[0113] The green dichroic filter 246 reflects the green light 236A
and directs the green light 236A along the pipe passageway 228A
while allowing red light 238A to pass therethrough. In FIGS. 17A
and 17B, the green dichroic filter 246 extends across the pipe
passageway 228A at an angle (e.g. approximately 45 degrees in one
embodiment) and reflects substantially all green light 236A towards
the trailing edge 228E. Additionally, the green dichroic filter 246
is positioned between the red region 228G and the green region
228H. In one embodiment, the green dichroic filter 246 is generally
rectangular plate shaped and has a size and shape that corresponds
to that of the pipe passageway 228A.
[0114] The blue pass filter 248 is positioned between the blue
light source 234 and the pipe passageway 228A, allows blue light
234A from the blue light source 234 to enter the pipe passageway
228A, and inhibits blue light 234A, green light 236A, and red light
238A in the pipe passageway 228A from exiting via the blue pass
filter 248. In one embodiment, the blue pass filter 248 is capable
of (i) transmitting a high percentage of blue light that is within
a blue predetermined angle of incidence range, (ii) reflecting a
high percentage blue light that is outside the blue predetermined
angle of incidence range, (iii) reflecting a high percentage of
green light, and (iv) reflecting a high percentage of red light. In
alternative, non-exclusive embodiments, the blue predetermined
angle of incidence range is between approximately 0 to 50; 0 to 45;
0 to 30; 0 to 20; 0 to 10; or 0 to 5 degrees.
[0115] In FIGS. 17A and 17B, the blue pass filter 248 is positioned
in the region aperture 228K in the wall 228D of the pipe body 228B
at the blue region 228I. In one embodiment, the blue pass filter
248 is generally rectangular plate shaped and fits into the
rectangular shaped region aperture 228K. Alternatively, the blue
pass filter 248 can have another configuration. As illustrated in
FIG. 17B, in one embodiment, the blue light 234A is directed into
the pipe passageway 228A substantially transverse to the passageway
axis 228L. For example, the blue light 234A can be directed into
the pipe passageway 228A at an angle of approximately 90 degrees
relative to the passageway axis 228L. Alternatively, the blue light
234A can be directed into the pipe passageway 228L at angles other
than 90 degrees.
[0116] The blue dichroic filter 250 reflects the blue light 234A
and directs the blue light 234A along the pipe passageway 228A
while allowing red light 238A and green light 236A to pass
therethrough. In FIGS. 17A and 17B, the blue dichroic filter 250
extends across the pipe passageway 228A at an angle (e.g.
approximately 45 degrees in one embodiment) between the green inlet
port and the blue inlet port, and reflects substantially all blue
light 234A towards the trailing edge 228E. Additionally, the blue
dichroic filter 250 is positioned between the green region 228H and
the blue region 228I. In one embodiment, the blue dichroic filter
250 is generally rectangular plate shaped and has a size and shape
that corresponds to that of the pipe passageway 228A.
[0117] Further, in one embodiment, the green dichroic filter 246
and the blue dichroic filter 250 are arranged in series along the
linear passageway axis 228L. This can reduce the footprint of the
light source assembly 212. Moreover, one or both of the dichroic
filters 246, 250 can have a high effective index (n greater than
approximately 1.75) to provide improved response for the tilted
coatings. As described above, each dichroic filter 246, 250 can be
a plate type filter. In one embodiment, a plate type filter is an
interference filter deposited onto a parallel plate substrate (e.g.
glass). The plate type dichroic filter may be designed to have a
high effective refractive index to improve filter response when
tilted at angles to incident light.
[0118] The design of each of the red pass filter 240, the end
reflector 242, the green pass filter 244, the green Dichroic filter
246, the blue pass filter 248, and the blue Dichroic filter 250 can
be varied pursuant to the teachings provided herein. In one
embodiment, each of the components includes a substrate 252 and
coating 254 that coats the substrate 252. As an example, the
substrate 252 can be a piece of glass or other transparent
material. The coating 254 for each of the components is uniquely
designed to achieve the desired level of reflectance for each of
these components. Suitable coatings 254 can include dielectric
materials and/or metal (silver or aluminum) material. The coatings
254 may have to be applied with multiple coating layers, and can be
deposited using a number of different methods including physical
vapor deposition such as ion beam sputtering, magnetron sputtering,
and ion assisted evaporation. One method for depositing the
coatings 254 is disclosed in U.S. Pat. No. 6,736,943.
[0119] In one embodiment, each of the pass filters 240, 244, 248 is
built as an edge filter using thin film interference technology.
The edge filter is designed to transmit at normal incidence
(perpendicular to the filter) or near-normal incidence at the
desired pass color (wavelength) while reflecting all other colors.
Furthermore, the filter also reflects the desired color at
non-normal angles. This is done using the angle shifting properties
of thin films where at high angles, the edge, reflection bands and
passbands of the filter shifts to shorter wavelengths. The shifting
of the reflection bands provides the desired effect of having the
same color which transmits at normal to be substantially reflected
at non-normal wavelengths. Using these techniques, the pass filters
240, 244, 248 can also be designed to transmit a wavelength at
normal (perpendicular to the filter), and reflect the wavelength at
relatively high angles.
[0120] FIG. 18 is a cut-away view of another embodiment of a light
source assembly 312 that is somewhat similar to the light source
assembly 212 illustrated in FIGS. 17A and 17B and described above.
However, in this embodiment, the red light source 338 is are
located at the leading edge 328E and the red light source 338
directs the red light 338A along the passageway axis 328L.
Moreover, the director assembly 330 does not include the end
reflector 242 because in this configuration, there is no need to
redirect the red light 338A. Additionally, this design does not
include the red pass filter because the red light 338A enters the
pipe passageway 328 along the passageway axis 328L and very little
red light 338A is reflected back at the red light source 338.
[0121] Furthermore, in FIG. 18, the green light source 336 and the
blue light source 334 are located in alternative sides of the
passageway axis 328L. With this design, the blue light 334A and the
green light 336A enter the pipe passageway 328A at an angle
(perpendicular in one example) relative to the passageway axis 328L
and the red light 338A enters the pipe passageway 328A aligned
(parallel) with the passageway axis 328L. Stated in another
fashion, in one embodiment, the red light 338A enters the pipe
passageway 328A at an angle of approximately 90 degree angle
relative to the blue light 334A and the green light 336A, and the
green light 336A enters the pipe passageway 328A at an angle of
approximately 180 degree angle relative to the blue light 334A.
However, other angles can be utilized.
[0122] FIG. 19 is a cut-away view of yet another embodiment of a
light source assembly 412 including an optical pipe 428, five
spaced apart light sources 433 and the director assembly 430
include four pass filters 439 and four dichroic filters 445. In
this embodiment, extra colors can improve color and brightness of
the light source assembly 412. Alternatively, the light source
assembly 412 could be designed with greater than or fewer than five
spaced apart light sources 433 and/or greater than or fewer than
four pass filters 439 and four dichroic filters 445.
[0123] In one embodiment, the light sources 433 include a red LED,
a magenta LED, a green LED, a cyan LED, and a blue LED.
Alternatively, other colors can be utilized.
[0124] In one embodiment, moving from the leading edge 428E to the
trailing edge (not shown in FIG. 19), the light sources 433 can be
are organized so that the light enters the pipe passageway 428A
from longest wavelengths to the shortest wavelengths.
[0125] FIG. 20 is a cut-away view of still another embodiment of a
light source assembly 512 that includes the optical pipe 528 and
three light sources 533. In this embodiment, the optical pipe 528
is a solid light pipe. For example, the optical pipe 528 can be a
polished, rectangular shaped piece of glass or other material.
Further, in the embodiment, the director assembly 530 includes two
dichroic filters 545 that are embedded into the optical pipe 528.
The dichroic filters 545 can be molded with the optical pipe
528.
[0126] Additionally, in this embodiment, the director assembly 530
does not include any pass filters. More specifically, in this
embodiment, light that enters the solid light pipe continues to
travel in the light pipe using total internal reflection.
Alternatively, one or more pass filters can be used that function
as an anti-reflection coating at normal and a reflector at high
angles.
[0127] In FIG. 20, the light sources 533 are illustrated as being
spaced apart from the optical pipe 528. Alternatively, the light
sources 533 can be positioned against the optical pipe 528 and
fixedly secured to the optical pipe 528.
[0128] FIG. 21 is a cut-away view of another embodiment of a light
source assembly 612 that is somewhat similar to the light source
assembly 212 illustrated in FIGS. 17A and 17B and described above.
However, in this embodiment, the director assembly 630 is slightly
different. More specifically, in this embodiment, the director
assembly 630 does not include (i) the red pass filter 240
(illustrated in FIG. 17B), (ii) the green pass filter 244
(illustrated in FIG. 17B), or (iii) the blue pass filter 248
(illustrated in FIG. 17B). In this embodiment, the pass filters
240, 244, 248 have been replaced with a transparent material such
as glass. Alternatively, the ports can be open.
[0129] FIG. 22 is a cut-away view of another embodiment of a light
source assembly 712 that is somewhat similar to the light source
assembly 212 illustrated in FIGS. 17A and 17B and described above.
However, in this embodiment, the light source assembly 712 includes
(i) a blue collimator 734B positioned between the blue light source
734 and the blue pass filter 248, (ii) a blue heat sink 734C that
cools the blue light source 734, (iii) a green collimator 736B
positioned between the green light source 736 and the green pass
filter 244, (iv) a green heat sink 736C that cools the green light
source 736, (v) a red collimator 738B positioned between the red
light source 738 and the red pass filter 740, and (vi) a red heat
sink 738C that cools the red light source 738. Alternatively, the
light source assembly 712 could be designed without one or more of
the collimators and/or the heat sinks.
[0130] Each collimator 734B, 736B, 738B collimates the light from
the respective light source 734, 736, 738 so that the light
entering the pipe passageway 728A is largely collimated. The design
of each collimator 734B, 736B, 738B can vary. In one embodiment,
each of the collimators 734B, 736B, 738B is tapered light pipe
collimator. Alternatively, one or more of the collimators 734B,
736B, 738B can be a lens type collimator Or a total internal
reflection type collimator.
[0131] Each heat sink 734C, 736C, 738C removes heat from the
respective light source 734, 736, 738. The design of each heat sink
734C, 736C, 738C can vary. In one embodiment, the heat sink 734C,
736C, 738C can include a plurality of spaced apart fins.
[0132] Further, in the embodiment illustrated in FIG. 22, the pipe
passageway 728A has a slightly different shape than that
illustrated in FIGS. 17A and 17B. In particular, in the embodiment,
the pipe passageway 728A is not tapered.
[0133] It should be noted that one or more of the collimators 734B,
736B, 738B and/or one or more of the heat sinks 734C, 736C, 738C
can be incorporated into one or other embodiments described or
illustrated herein.
[0134] FIGS. 23A and 23B are alternative graphs that illustrate the
properties of alternative pass filters in more detail. In
particular, FIG. 23A is a graph that illustrates the properties of
one embodiment of the blue pass filter, and FIG. 23B is a graph
that illustrates the properties of one embodiment of the green pass
filter. It should be noted that the coating could be designed to
have other characteristics than that illustrated in FIGS. 23A and
23B.
[0135] FIG. 24 is a chart that lists the layer of materials used
for making a one embodiment of a blue pass filter. Starting with
the substrate, the layers of materials (detail in FIG. 24) are
deposited. The thickness of each layer is in nanometers.
[0136] While the particular apparatus 110 as herein shown and
disclosed in detail is fully capable of obtaining the objects and
providing the advantages herein before stated, it is to be
understood that it is merely illustrative of the presently
preferred embodiments of the invention and that no limitations are
intended to the details of construction or design herein shown
other than as described in the appended claims.
[0137] Those of ordinary skill in the art will recognize that the
light source assemblies disclosed here present significant
technical and commercial advantages. Likewise, those of ordinary
skill in the art will recognize that innumerable modifications can
be made and other features are aspect added without departing from
the principles disclosed here.
* * * * *