U.S. patent application number 10/708272 was filed with the patent office on 2005-01-13 for head-mounted display and optical engine thereof.
This patent application is currently assigned to LEADTEK RESEARCH INC.. Invention is credited to Wu, Shih-Ping.
Application Number | 20050007672 10/708272 |
Document ID | / |
Family ID | 33563308 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050007672 |
Kind Code |
A1 |
Wu, Shih-Ping |
January 13, 2005 |
HEAD-MOUNTED DISPLAY AND OPTICAL ENGINE THEREOF
Abstract
A head-mounted display comprises monocular or binocular display
chambers. Each display chamber is equipped with an optical engine
that displays images. The mechanism of the optical engine is as
follows: cast rays from a light source onto an LCoS device through
a first polarizer, and an image is formed with rays, which reflect
off the bottom of the LCoS device. The reflective rays penetrate
the first polarizer and a film-coated beam splitter. With a concave
mirror, the image is magnified and projected onto the surface of
the beam splitter. Finally, the magnified image is formed in a
viewer's eyeballs by means of the beam splitter.
Inventors: |
Wu, Shih-Ping; (Chung Ho
City, TW) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
SUITE 800
1990 M STREET NW
WASHINGTON
DC
20036-3425
US
|
Assignee: |
LEADTEK RESEARCH INC.
18FL, No. 166, Chien-Yi Road Chung Ho City
Taipei Hsien
TW
|
Family ID: |
33563308 |
Appl. No.: |
10/708272 |
Filed: |
February 20, 2004 |
Current U.S.
Class: |
359/630 |
Current CPC
Class: |
G02B 27/0172 20130101;
G02B 2027/0178 20130101; G02B 27/017 20130101; G02B 2027/0132
20130101 |
Class at
Publication: |
359/630 |
International
Class: |
G02F 001/03; G02F
001/07; G02B 027/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 9, 2003 |
TW |
092118771 |
Claims
1. An optical engine for a head-mounted display capable of forming
images before man's eyeballs to be watched, comprising: a first
polarizer; a light source emitting rays toward the first polarizer;
an LCoS device for generating the images and reflecting reflective
rays from the first polarizer to penetrate the first polarizer; a
concave mirror; and a beam splitter for refracting the rays of the
images having penetrated the first polarizer to the concave mirror,
which then magnifies the images and projects the magnified images
on the beam splitter to be watched.
2. The optical engine for a head-mounted display of claim 1,
wherein an included angle between a luminous surface of the light
source and a surface of the LCoS device is in a range of 15 to 25
degrees, and an included angle between a surface of the first
polarizer and a surface of the LCoS device is in a range of 25 to
35 degrees.
3. The optical engine for a head-mounted display of claim 1,
wherein a luminous surface of the light source is perpendicular to
the LCoS device, and an included angle between the first polarizer
and the surface of the LCoS device is substantially 45 degrees.
4. The optical engine for a head-mounted display of claim 1,
further comprising a pre-polarizer placed between the beam splitter
and the eyeballs.
5. The optical engine for a head-mounted display of claim 1,
wherein the light source includes: a light generator for generating
visible rays; a pre-polarizer allowing a part of the visible rays
in a certain polarized direction to pass through; and a Fresnel
lens for changing the rays passing through the pre-polarizer into
parallel rays.
6. The optical engine for a head-mounted display of claim 5,
wherein the light generator is composed of a red LED, a blue LED
and a green LED.
7. The optical engine for a head-mounted display of claim 1,
wherein the first polarizer is substantially parallel to the beam
splitter.
8. The optical engine for a head-mounted display of claim 7,
wherein the first polarizer and the beam splitter are combined into
a polarized beam splitter.
9. The optical engine for a head-mounted display of claim 1,
wherein a coated film is formed on the surface of the beam
splitter.
10. The optical engine for a head-mounted display of claim 1,
wherein the concave mirror is a non-spherical concave mirror.
11. An optical engine for a head-mounted display capable of forming
images before man's eyeballs, comprising: a first polarizer; a
light source for emitting rays toward the first polarizer; an LCoS
device for generating the images and reflecting reflective rays
from the first polarizer to penetrate the first polarizer; a
concave mirror; and a beam splitter reflecting the rays of images
having penetrated the first polarizer to the concave mirror, which
magnifies the images and has the magnified images pass through the
beam splitter to the eyeballs.
12. The optical engine for a head-mounted display of claim 11,
wherein an included angle between a luminous surface of the light
source and a surface of the LCoS device is in a range of 15 to 25
degrees, and an included angle between the surface of the first
polarizer and the surface of the LCoS device is in a range of 25 to
35 degrees.
13. The optical engine for a head-mounted display of claim 11,
further comprising a pre-polarizer placed between the beam splitter
and the eyeballs.
14. The optical engine for a head-mounted display of claim 11,
wherein the light source includes: a light generator for generating
visible rays; a pre-polarizer allowing a part of the visible rays
in a certain polarized direction to pass through; and a Fresnel
lens for changing the rays passing through the pre-polarizer into
parallel rays.
15. The optical engine for a head-mounted display of claim 14,
wherein the light generator is composed of a red LED, a blue LED
and a green LED.
16. The optical engine for a head-mounted display of claim 11,
wherein the concave mirror is a non-spherical concave mirror.
17. A head-mounted display, comprising: at least one display
chamber having an optical engine therein, wherein the optical
engine includes: a first polarizer; a light source for emitting
rays toward the first polarizer; an LCoS device for generating
images and reflecting reflective rays from the first polarizer to
penetrate the first polarizer; a concave mirror; and a beam
splitter refracting the rays of the images having penetrated the
first polarizer to the concave mirror, which magnifies the images
and projects the magnified images on the beam splitter to be
watched; and a frame for holding the display chamber.
18. The head-mounted display of claim 17, further comprising an
earpiece fixed on the frame.
19. A head-mounted display, comprising: at least one display
chamber having an optical engine therein, wherein the optical
engine includes: a first polarizer; a light source for emitting
rays toward the first polarizer; an LCoS device for generating
images and reflecting reflective rays from the first polarizer to
penetrate the first polarizer; a concave mirror; and a beam
splitter reflecting the rays of the images having penetrated the
first polarizer to the concave mirror, which magnifies the images
and redirects the magnified images through the beam splitter to the
eyeballs; and a frame for holding the display chamber.
20. The head-mounted display of claim 19, further comprising an
earpiece fixed on the frame.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The present invention relates to a head-mounted display
(HMD) and the optical engine thereof and more specifically to a
head-mounted display capable of showing images formed by means of
an LCoS (liquid crystal on chip) device.
[0003] 2. Description of the Related Art
[0004] In recent years, virtual reality, a type of computer
simulation technology, has been vigorously developed, and can make
wearers temporarily feel that they exist in the three-dimensional
(3D) space of a simulated world. Through a head-mounted display,
the imitative voices and images are sent directly to the sense
organs of the wearer. Due to previous practical experiences, the
wearer would really think of these imaginary imagines as real ones.
Currently, such apparatus has been widely applied in computer
games. If a space positioner and a 3D joystick are added to the
apparatus, there would be feeling of truer reality.
[0005] In addition to being the standard apparatus of virtual
reality, the head-mounted display may be used to further replace
the display of a TV or a computer. Furthermore, it is also an
optimal solution for privacy when one uses a notebook in public
place to avoid peeping of the others. Also, many workers who
constantly move about, for example, researchers, soldiers or
stockjobbers, need to complete their works by wearing a
head-mounted display.
[0006] In as early as the 1960s, a professor from the University of
Utah, the USA, formed the first head-mounted display with a cathode
ray tube monitor, an optical system intended for focusing, and a
computerized image creation unit, wherein the process of displaying
signals on the screen was controlled by means of rotation of head.
Afterward, thin film transistor liquid crystal display (TFT-LCD)
was applied to head-mounted displays, and thus head-mounted
displays became lighter and have been used increasingly in fields
like entertainment, medicine, education, etc.
[0007] Recently, the technology of miniaturized LCoS displays has
forged into maturity, and the miniaturized LCoS displays have been
applied to the image generator used in head-mounted displays. The
principle of manufacturing LCoS displays is as follows: form an
active matrix driving circuit for driving liquid crystal materials
on silicon substrate with a CMOS manufacturing process, and stack a
liquid crystal layer and a glass plate on the silicon substrate to
form an LCoS display. A light source emits a ray that enters the
liquid crystal layer through the glass plate and returns to the
upper surface of the glass plate by reflection, and eventually the
LCoS display reflects the predetermined image. Hence, LCoS displays
are also known as reflective liquid crystal displays. Since LCoS
displays have a relatively high aperture ratio, luminance,
resolution and contrast, and the equipment for their manufacturing
process is relatively common, LCoS displays will be the mainstream
image generators for head-mounted displays.
BRIEF SUMMARY
[0008] The objective of the present invention is to provide a
head-mounted display and its optical engine, wherein images are
formed by means of an LCoS device, and interfering rays are
filtered out by means of the relative positions of a light source
and a polarizer so as to secure good imaging quality.
[0009] In order to achieve the objective, the present invention
discloses a head-mounted display and an optical engine thereof. The
head-mounted display comprises monocular or binocular display
chambers. Each display chamber is equipped with an optical engine
that displays images. The mechanism of the optical engine is as
follows: cast rays from a light source onto an LCoS device through
a first polarizer, and an image is formed with rays, which reflect
off the bottom of the LCoS device. The reflective rays penetrate
the first polarizer and a film-coated beam splitter. With a concave
mirror, the image is magnified and projected onto the surface of
the beam splitter. Finally, the magnified image is formed in a
viewer's eyeballs by means of the beam splitter.
DESCRIPTION OF THE DRAWINGS
[0010] The invention will be described according to the appended
drawings in which:
[0011] FIG. 1 is a perspective diagram of the head-mounted display
in accordance with the present invention;
[0012] FIG. 2(a) is a schematic diagram of the optical engine in
accordance with the first embodiment of the present invention;
[0013] FIG. 2(b) is a magnified diagram of the portion B in FIG.
2(a);
[0014] FIG. 3 is a schematic diagram of the optical engine in
accordance with the second embodiment of the present invention;
and
[0015] FIG. 4 is a schematic diagram of the optical engine in
accordance with the third embodiment of the present invention.
DETAILED DESCRIPTION
[0016] FIG. 1 is a perspective diagram of the head-mounted display
in accordance with the present invention. The head-mounted display
1 comprises the display chambers 2 in-tended for the right eye and
the left eye respectively, though its alternative design may have
one single display chamber 2 intended for users who move about
during work time. An optical engine 3, which creates images, is
installed in each display chamber 2. With both eyes close to the
display chambers 2, a user 8 browses various pictures displayed by
the head-mounted display 1. In addition to the display chambers 2,
the frame 5 of the head-mounted display 1 may be equipped with an
earpiece 4 to make the head-mounted display more useful.
[0017] As shown in FIG. 2(a), the optical engine 3 essentially
comprises an optical system composed of an LCoS device 12, a light
source 16, a first polarizer 13, a beam splitter 14 and a concave
mirror 15. The LCoS device 12 is installed on a circuit board 11.
The light source 16 is obliquely fixed on the circuit board 11. The
first polarizer 13 reflects part of the rays emitted by the light
source 16 so that the reflective rays fall on the LCoS device 12,
then the LCoS 12 reflects the rays which form a specific image so
that they fall on the first polarizer 13. Part of the rays
penetrate the first polarizer 13 and reach the beam splitter 14.
Owing to a coated film on the surface of the beam splitter 14,
incident rays are sent to the concave mirror 15 below by
refraction, and the rays backwardly reflect off the concave mirror
15 and then travel in the direction of an analyzer 17.
[0018] The concave mirror 15 magnifies the image and sends it to
the surface of the film-coated beam splitter 14 by reflection, and
then the magnified image reflects off the beam splitter 14 and is
finally formed in the eyeballs 80 of a user 8. As a result, the
user 8 is able to watch the magnified image displayed by the
optical engine 3 and centered at a visual axis 18 in a way
comparable to the large-screen effect of an ordinary desktop
monitor. The concave mirror 15 adopted in the present invention
will magnify images to a greater extent and display images better,
if it is non-spherical in shape. The analyzer 17 lying between the
beam splitter 14 and the eyeballs 80 filters out stray light,
making the images entering the eyeballs 80 softer.
[0019] FIG. 2(b) is a schematic diagram of the magnified part B
shown in FIG. 2(a). A 20.degree..+-.5.degree. included angle
between the luminous surface of the light source 16 and the surface
of the LCoS 12, coupled with a 30.degree..+-.5.degree. included
angle between the first polarizer 13 and the surface of the LCoS
12, makes the optimal relative relationship, eliminating
undesirable images like ghosting. The light source 16 comprises a
light generator 161, a pre-polarizer 162 and a Fresnel lens 163. In
general, the light generator 161 can be a tri-color RBG LED. The
purpose of the pre-polarizer 162 is to absorb polarized light that
travels in a certain direction but permit the passage of polarized
light that travels in a different direction. The Fresnel lens 163
turns the passing rays into parallel rays and enables even
distribution of light intensity.
[0020] FIG. 3 is a schematic diagram of the second preferred
embodiment of the optical engine put forth in the present
invention. Unlike FIG. 2, FIG. 3 shows a first polarizer 13' found
in a position parallel to the beam splitter 14 instead of its
previous position, a light source 16' lying to the right of the
first polarizer 13', and the parallel rays emitted from the light
source 16' falling on the first polarizer 13' at an incident angle
of 45.degree. approximately. The first polarizer 13' reflects part
of the light emitted by the light source 16' so that it falls on
the LCoS device 12. The LCoS device 12 then reflects the rays which
form a specific image, so that the rays return to the first
polarizer 13'. Part of the rays penetrate the first polarizer 13'
before they reach the beam splitter 14. Owing to a coated film on
the surface of the beam splitter 14, incident rays are sent to the
concave mirror 15 below by refraction, and the rays backwardly
reflect off the concave mirror 15 and then travel in the direction
of an analyzer 17. In terms of its function, the first polarizer
13' may be directly incorporated into the beam splitter 14, that
is, a polarizing beam splitter may substitute for the beam splitter
14 and the first polarizer 13'.
[0021] FIG. 4 is a schematic diagram of the third preferred
embodiment of the optical engine put forth in the present
invention. As shown in FIG. 4, both the concave mirror 15 and the
LCoS device 12 are installed on the same side of the beam splitter
14'. The first polarizer 13 reflects part of the light emitted by
the light source 16 to send it to the LCoS device 12. The LCoS 12
then reflects the rays that form a specific image, so that the rays
return to the first polarizer 13. The rays that form the specific
image penetrate the first polarizer 13 before they reach the beam
splitter 14'. Owing to a coated film on the surface of the beam
splitter 14', incident rays are sent to the concave mirror 15 on
the right side by refraction, and the rays backwardly reflect off
the concave mirror 15 and then travel in the direction of the
analyzer 17.
[0022] The above-described embodiments of the present invention are
intended to be illustrative only. Numerous alternative embodiments
may be devised by persons skilled in the art without departing from
the scope of the following claims.
* * * * *