U.S. patent application number 13/357737 was filed with the patent office on 2013-07-25 for three dimensional image projector.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. The applicant listed for this patent is Casimer M. DeCusatis. Invention is credited to Casimer M. DeCusatis.
Application Number | 20130188149 13/357737 |
Document ID | / |
Family ID | 48796955 |
Filed Date | 2013-07-25 |
United States Patent
Application |
20130188149 |
Kind Code |
A1 |
DeCusatis; Casimer M. |
July 25, 2013 |
THREE DIMENSIONAL IMAGE PROJECTOR
Abstract
A system is provided for projecting a three-dimensional image.
The system includes a first light source, the first light source
emitting light in a first direction and a second light source
emitting light in a second direction. A beam splitter device is
disposed adjacent each light source and an imaging device is
disposed adjacent the beam splitter device. Light from the first
light source and the second light source travel a common optical
path to a projector lens assembly.
Inventors: |
DeCusatis; Casimer M.;
(Poughkeepsie, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DeCusatis; Casimer M. |
Poughkeepsie |
NY |
US |
|
|
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
Armonk
NY
|
Family ID: |
48796955 |
Appl. No.: |
13/357737 |
Filed: |
January 25, 2012 |
Current U.S.
Class: |
353/8 ; 353/121;
353/20; 362/19 |
Current CPC
Class: |
F21V 9/14 20130101; G02B
30/25 20200101; G03B 35/26 20130101; G03B 21/14 20130101; G03B
33/12 20130101; G02B 27/1033 20130101 |
Class at
Publication: |
353/8 ; 362/19;
353/20; 353/121 |
International
Class: |
G02B 27/26 20060101
G02B027/26; G03B 21/14 20060101 G03B021/14; F21V 9/14 20060101
F21V009/14 |
Claims
1-13. (canceled)
14. A system comprising: a first light source emitting light having
a first polarization; a second light source emitting light having a
second polarization; a first beam splitter device (PBS) adjacent
the first light source; a second PBS adjacent the second light
source; a first imaging device adjacent the first PBS; a second
imaging device adjacent the second PBS; a third PBS disposed
between the first PBS and the second PBS; a projection lens
assembly located adjacent the third PBS; and, a mirror disposed on
the side of the third PBS opposite the projection lens
assembly.
15. The system of claim 14 wherein the first polarization is
orthogonal to the second polarization.
16. The system of claim 14 wherein the first light source emits a
first light in a first direction and the second light source emits
a second light in a second direction, the second direction being
opposite the first direction.
17. The system of claim 14 wherein the first imaging device and the
second imaging device are LCoS devices.
18. The system of claim 14 wherein the light emitted by the first
light source and the light emitted by the second light source are
transmitted along the same optical path from the third PBS to the
projection lens assembly.
19. The system of claim 14 further comprising: a first fly's eye
lens arranged between the first light source and the first PBS;
and, a first pre-polarizer lens arranged between the first fly's
eye lens and the first PBS.
20. The system of claim 19 further comprising: a second fly's eye
lens arranged between the second light source and the second PBS;
and, a second pre-polarizer lens arranged between the second fly's
eye lens and the second PBS.
21. The system of claim 19 wherein the first light source
comprises: a plurality of first LED devices; a plurality of first
light collection optics, each of the plurality of first light
collection optics associated with one of the plurality of first LED
devices; and, a first dichroic color combiner disposed between the
plurality of first light collection optics, the first dichroic
color combiner arranged to direct light from the plurality of first
LED devices into the first fly's eye lens.
22. The system of claim 20 wherein the second light source
comprises: a plurality of second LED devices; a plurality of second
light collection optics, each of the plurality of second light
collection optics associated with one of the plurality of second
LED devices; and, a second dichroic color combiner disposed between
the plurality of second light collection optics, the second
dichroic color combiner arranged to direct light from the plurality
of second LED devices into the second fly's eye lens.
23. The system of claim 14 further comprising a feedback circuit
coupled to the first light source, the second light source, the
first PBS, the second PBS, the first imaging device, and the second
imaging device.
Description
BACKGROUND
[0001] The present invention relates to a stereoscopic three
dimensional image projector, and more specifically, to a small
three dimensional projector usable with passive glasses.
[0002] Three dimensional (3D) movies and pictures have become a
popular form of entertainment due to the increased realism of the
images. 3D images utilize the human physical trait of binocular
vision. Human eyes are spaced about 2 inches (5 centimeters) apart;
therefore each eye sees the world from a slightly different
perspective. The brain receives both images and has a binocular
vision function that correlate the difference between what each eye
sees to determine distance. The determination of the distance
provides the three-dimensional effect that a person sees.
[0003] To create a binocular image on a two dimensional surface,
such as a movie or television screen, the user typically wears
glasses. The glasses alter the way that the user views the images
to create the simulated 3D effect. Typically there are two types of
glasses, passive glasses and active glasses. The type of glasses
used will depend on the type of image projection system being
used.
[0004] Passive glasses rely upon an optical effect created by using
different lenses for each eye. The projection system emits a
sequential series of images where subsequent images are slightly
offset. The images are arranged such that the user sees the first
image through a first lens of the glasses (e.g. the right eye) and
the second image is seen with the other lens (e.g. the left eye).
Since the images are projected quickly, the user does not notice
the multiple images, but rather sees a three dimensional effect.
Originally, passive glasses used different color lenses to filter
out images; however this limited the use of 3D images when full
color images are desired. To alleviate this issue, polarized lenses
were developed where each lens of the glasses allowed the
transmission of different polarized light. The polarized passive
lenses allowed for full color 3D images to be transmitted. Passive
lenses are more common with projector type systems, such as movie
theaters for example, where multiple projectors may be used to
project the images on a screen.
[0005] The development of 3D television systems created a new
challenge as there typically isn't enough room for multiple
projectors. To accommodate this, active lenses were created. With
an active lens, the glasses wirelessly communicate with the
projector to synchronize the glasses operation with the images
being displayed. With active glasses, the lenses are typically
liquid crystal displays that can switch between transmitting light
and blocking light. In this way, the glasses may rapidly switch the
left and right lenses between clear and opaque. While the glasses
are switching, the television is projecting a series of sequential
images. When this switching is synchronized between the television
and the glasses, the user experiences a three dimensional
effect.
[0006] Accordingly, while existing three dimensional projectors are
suitable for their intended purpose a need for improvement remains,
particularly in providing a system with a single projector that can
project images viewable with passive glasses.
SUMMARY
[0007] According to one embodiment of the invention, a method is
provided having a first light source and a second light source. A
first polarizing beam splitter (PBS) is disposed adjacent the first
light source and a second PBS is located adjacent the second light
source. A first imaging device is adjacent the first PBS and a
second imaging device is adjacent the second PBS. Additionally,
disposed between the first PBS and the second PBS is a third PBS.
The first light source emits a first light. The first light is
reflected from the first PBS onto the first imaging device. The
image reflects from the first imaging device to the third PBS.
[0008] According to another embodiment of the present invention, a
method of projecting a three dimensional image is provided having a
first light source with a first polarization and a second light
source with a second orientation wherein the first polarization is
orthogonal to the second polarization. A first eye image of a first
color is projected from the first light source. A second eye image
of the same first color is projected from the second light source.
A first eye image of a second color is projected from the first
light source. A second eye image of the same second color is
projected from the second light source. A first eye image of a
third color is projected from the first light source. A second eye
image of a third color is projected from the second light
source.
[0009] According to another embodiment of the present invention, a
projector system for a portable electronic device is provided
having a first light source that emits light having a first
polarization. A second light source emits a light having a second
polarization. A first polarizing beam splitter device (PBS) is
adjacent the first light source and a second PBS is adjacent the
second PBS. A first imaging device is adjacent the first PBS and a
second imaging device is adjacent the second PBS. A third PBS is
disposed between the first PBS and the second PBS. A projection
lens assembly is located on one side of the third PBS and a mirror
is located on the opposite side of the third PBS.
[0010] Additional features and advantages are realized through the
techniques of the present invention. Other embodiments and aspects
of the invention are described in detail herein and are considered
a part of the claimed invention. For a better understanding of the
invention with the advantages and the features, refer to the
description and to the drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0011] The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The forgoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0012] FIG. 1 is a schematic view of a three-dimensional image
projector in accordance with an embodiment of the invention;
[0013] FIG. 2 is a flow chart for a method of operating a
three-dimensional image projector in accordance with an embodiment
of the invention; and,
[0014] FIG. 3 is another flow chart for a method of operating the
three-dimensional image projector in accordance with an embodiment
of the invention.
DETAILED DESCRIPTION
[0015] Contemporary three-dimensional (3D) image projectors that
use passive glasses have typically use two projectors. Previous
efforts to use only a single projector rely upon an active lens
within the projector that switches between the sequential images.
It should be appreciated that substantial costs may be involved in
using redundant projectors or having a costly active lens. Further,
these techniques do not scale well as users desire comparable
performance from smaller and smaller projector packages.
[0016] A second type of projector uses active glasses having a
liquid crystal diode (LCD) lens that coordinates with the projector
(typically a television). The active glasses alternately block one
of the lenses such that the user will see sequential images through
alternating lenses. While active glasses perform well to create the
3D effect for the user, they also have some less desirable
characteristics. The active glasses require an energy source such
as a battery that needs to be periodically recharged or replaced.
If the communication between the television and the glasses is
interrupted, the 3D effect may be lost. Further, due to the
complexity of the system, the active glasses tend to be much more
costly.
[0017] With reference now to FIG. 1, a three-dimensional projector
20 is shown for projecting a three-dimensional (3D) image in
accordance with an embodiment of the invention. The projector 20
includes a first light source 22 and a second light source 24
arranged to emit light in opposite directions. The direction of
light from first light source 22, indicated by arrow 26, is
substantially 180 degrees apart from the direction of the light
from second light source 24, as indicated by arrow 28. The first
and second light sources 22, 24 may be disposed on opposite sides
of centerline 23. In one embodiment, the first and second light
sources 22, 24 are offset from each other. The first light source
22 is spaced a distance D1 from a centerline 23 of the projector
and the second light source 24 is spaced a distance D2 from the
centerline 23. The first and second light sources 22, 24 may be
spaced equidistantly from centerline 23 such that distance D1 is
equal to distance D2. In the exemplary embodiment, each light
source includes three monochromatic light emitting diodes (LED), a
red LED 30, a green LED 32 and a blue LED 34. The LED's 30, 32, 34
are arranged to form three sides of a square and direct light
toward the center of the first and second light sources 22, 24.
Each LED 30, 32, 34 may be coupled to direct light into a light
collection optic 36.
[0018] The light collection optic 36 directs the light from the
LED's 30, 32, 34 into a dichroic color combiner 38. The dichroic
color combiner 38 combines light from the LED's to create a desired
light color. The light from the first light source 22 exits via an
open side 40 and passes through a first fly's eye lens 42 and a
first pre-polarizer lens 44. The first fly's eye lens 42 consists
of an array of lenslets that have the effect of breaking the
transmitted light into many components and projecting them evenly
over the field of view. The result is even, bright illumination
without any reduction in light intensity at the periphery of the
projected light. The first pre-polarizer lens 44 changes the
polarization of the outgoing light to have a desired polarization
characteristic that is suitable for the imaging device being used.
Once the light leaves first the pre-polarization lens 44, the light
passes into a first polarizing beam splitter device 54 (PBS).
[0019] Similar to the first light source 22, the light from the
second light source 24 leaves an open side 46 and enters a second
fly's eye lens 48 and a second pre-polarization lens 50. After
being conditioned by these lenses 48, 50, the second light enters a
second PBS 58.
[0020] A PBS 54, 56, 58 is an optical component that splits
incident light rays into a first (transmitted) polarization
component and a second (reflected) polarization component. A first
PBS 54 is positioned adjacent to the pre-polarizer lens 44 and a
second PBS 58 is located adjacent to pre-polarizer lens 50. First
and second imaging devices 60, 64 are positioned adjacent each of
the first and second PBS 54, 58 respectively. In one embodiment,
the first PBS 54 and the first imaging device 60 are arranged on an
opposite side of centerline 23 from the second PBS 58 and second
imaging device 64. The first imaging device 60 and the second
imaging device 64 may be arranged such that the imaging surfaces
62, 66 are on opposing sides of centerline 23. In still another
embodiment, the imaging surfaces are disposed to reflect light in a
direction substantially perpendicular to the arrows 26 and 28. In
the exemplary embodiment, the imaging devices 60, 64 may be liquid
crystal on silicone (LCoS) type devices that have an imaging
surface 62, 66 adjacent each respective PBS 54, 58. In operation,
the light from either lighting source 22, 24 reflects off the
surface 62, 66 of the respective imaging device 60, 64 and back
through the respective PBS 54, 58 to a middle or third PBS 56. For
example, if the light was emitted by the first light source 22, the
first light, reflecting off of the surface 62 of the first imaging
device 60, will pass through the first PBS 54 to the third PBS 56
which in turn reflects the first light into a projection lens
assembly 70 and out of the device 20. Similarly, if the light was
emitted by the second light source 24, the second light will
reflect off of the surface 66 of second imaging device 64, and pass
through second PBS 58 to third PBS 56. Because the polarization of
the second light is orthogonal to the polarization of the first
light, the third PBS 56 reflects the light outwards in a direction
opposite the projection lens assembly 70 and towards a mirror 68.
The second light reflects off of mirror 68 and reenters third PBS
56. Because the second light enters the third PBS 56 from a
different angle, the light passes through PBS 56 and continues
outward towards the projection lens assembly 70 along the same
optical path as the first light. Thus the light from both the first
and second light sources 22, 24 exits the projector 20 and is
transmitted along a common optical path. In the present embodiment,
use of an LCoS imaging device 60, 64 provides advantages in that
the LCoS device inherently polarizes the reflected light.
[0021] To create a 3D image, the image content for the left and
right eye needs to be independently modulated with orthogonal
polarizations of light. The light emitted from each light source
has a polarization orthogonal to the light emitted from the other
light source; consequently, the first light source provides all of
the image content for a first eye, and the second light source
provides all of the image content for the other or second eye.
Referring to the flow chart in FIG. 2, the projector device 20
works by activating the first and second light sources sequentially
such that both the left and right eye images of a first color are
projected before either the left or right eye image of a second
color. In block 90, a light source, such as light source 22, emits
a light such that an image for a first eye, such as the left eye,
is projected from projector 20. This image will be a first color
from the plurality of LEDs within the light source, such as red. In
block 110, another light source, such as light source 24, will
similarly emit a light of the same color, such that an image for a
second eye, for example the right eye, is projected out of
projector 20. Once both light sources have projected an image of a
first color, the first light source 22 will then project an image
of a second color, such as blue, as in block 130. In block 132, the
second light source will then project an image of the same second
color. This pattern repeats in blocks 134 and 136 such that the
first and second light sources 22, 24 sequentially produce images
of a third color from the plurality of LEDs within both light
sources, such as green. Although the colors need not be projected
in any particular order, conventional systems commonly emit a red
light first, a green light second, and lastly a blue light.
[0022] In some embodiments, it should be appreciated that the
combination of light sources 22 and 24, polarized beam splitters
(PBS) 54, 56, and 58, and LCoS devices 60, 64 provide advantages in
reducing the size of the projector into the category of a
pico-projector or micro-projector. These small projectors may be
suitable to be used in a portable electronic device, such as but
not limited to a cellular phone, a tablet computer, a laptop
computer, and a hand-held gaming device for example. Embodiments of
the present invention may also be used in non-portable devices,
such as but not limited to a desktop computer or a television for
example.
[0023] The projector 20 may also include an optional feedback
circuit 25. The feedback circuit 25 is electrically coupled to
communicate with the first light source 22, the second light source
24, the first and second PBS 54, 58 and the first and second
imaging devices 60, 64. The feedback circuit 25 provides a
modulation signal to the light sources 22, 24, to keep the light
sources and LCoS imaging devices synchronized during operation. The
feedback circuit 25 may additionally include LED drivers for both
the first and second light sources 22, 24 to control the order of
the LED colors being used in the images emitted by each source. The
feedback circuit 25 provides functionality to enable each light
source 22, 24 to emit the correct color light that corresponds to
an image being displayed on the surface 62, 66 of the respective
imaging devices.
[0024] Referring now to FIG. 3, another method 80 is shown for
operating a three dimensional image projector. The method 80 first
synchronizes the light sources in block 84 and creates a first eye
image in block 90. To create the first image, a light source, such
as first light source 22, emits a first light of a first color LED,
for example red, from the plurality of LEDS within the first light
source in block 92. In block 94, the light is combined by the
dichroic color combiner 38 and passes through a first fly's eye
lens 42 which projects the transmitted light evenly over the field
of view. The light then passes through the pre-polarizer lens 44,
as shown in block 96, where the light is given a certain
polarization such that it reflects from the first PBS 54. The light
from the first light source reflects off of the first PBS 54 and
onto a first imaging device 60, such as an LCoS imaging device. In
block 98, the first light reflects off of the first imaging device
60 and through the first PBS 54 to a middle or third PBS 56
disposed between the first and second PBS 54, 58. The light
reflects out of third PBS 56 to a projection lens assembly 70 to
project a first eye image of a first color, such as a red image for
the left eye. After the first eye image of a first color is
projected, a second eye image of the same first color is then
projected, as shown in block 110. To project this second eye image,
in block 112 a light source, such as second light source 24, emits
a second light of the same color as the first light emitted by
first light source 22. The second light similarly is combined by a
dichroic color combiner 38 and passes through a second fly's eye
lens 48 which projects the transmitted light evenly over the field
of view collected by a dichroic mirror. In block 116, the second
light is polarized by second pre-polarizer lens 50 such that it
reflects from the second PBS 58 and onto the second imaging device
64. The light then reflects off of the surface 66 of the second
imaging device 64 in block 118, and through the second PBS 58 to a
third PBS 56.
[0025] Because of the polarization of the second light, which is
orthogonal to the light emitted by the first light source, the
second light is reflected from third PBS 56 in a direction opposite
the projection lens assembly 70 to a mirror 68 as shown in block
120. The second light reflects off the mirror 68, back through the
third PBS 56 and outwards towards the projection lens assembly 70
along the same optical path as the first light. In one example,
this second light may be the red image for the right eye. Once both
the first and second light sources have emitted images using the
same first color LED, the first light source will then emit another
image for the first eye using a second color LED from the plurality
of LEDS within the first light source, as shown in block 130. Once
the second color image from first light source has been projected,
the second light source will similarly produce an image using the
same color LED as the prior first light source emission, but a
different color LED than the previous second light source image.
For example, if the first set of left and right eye images were
red, the next set of left and right eye images from the first and
second light sources could be either green or blue in color. This
cycle continues in blocks 134 and 136 such that both of the images
produced by first light source and second light source are the
remaining color from the plurality of LEDs within the light source.
Projection of all three sets of left and right eye images produces
a three-dimensional color image visible to a viewer wearing passive
lenses. The method then loops back to block 90 to continue
projecting images from the projector device 20 in the color
sequence.
[0026] Embodiments of the present invention provide for a small,
reliable three-dimensional projector. Embodiments of the present
invention provide advantages of having multiple light sources that
are arranged to have the same path length for projecting the image.
Embodiments provide advantages in emitting a three-dimensional
image usable with passive glasses.
[0027] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one more other features, integers,
steps, operations, element components, and/or groups thereof.
[0028] The corresponding structures, materials, acts, and
equivalents of all means or step plus function elements in the
claims below are intended to include any structure, material, or
act for performing the function in combination with other claimed
elements as specifically claimed. The description of the present
invention has been presented for purposes of illustration and
description, but is not intended to be exhaustive or limited to the
invention in the form disclosed. Many modifications and variations
will be apparent to those of ordinary skill in the art without
departing from the scope and spirit of the invention. The
embodiment was chosen and described in order to best explain the
principles of the invention and the practical application, and to
enable others of ordinary skill in the art to understand the
invention for various embodiments with various modifications as are
suited to the particular use contemplated
[0029] The flow diagrams depicted herein are just one example.
There may be many variations to this diagram or the steps (or
operations) described therein without departing from the spirit of
the invention. For instance, the steps may be performed in a
differing order or steps may be added, deleted or modified. All of
these variations are considered a part of the claimed
invention.
[0030] While the preferred embodiment to the invention had been
described, it will be understood that those skilled in the art,
both now and in the future, may make various improvements and
enhancements which fall within the scope of the claims which
follow. These claims should be construed to maintain the proper
protection for the invention first described.
* * * * *