U.S. patent application number 11/408049 was filed with the patent office on 2007-07-26 for rotational micro mirror.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Jin-woo Cho, Hee-Moon Jeong, Jin-ho Lee.
Application Number | 20070171496 11/408049 |
Document ID | / |
Family ID | 38106417 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070171496 |
Kind Code |
A1 |
Jeong; Hee-Moon ; et
al. |
July 26, 2007 |
ROTATIONAL MICRO MIRROR
Abstract
A rotational micro mirror is rapidly driven, has a large driving
angle, and is structurally stable. The rotational micro mirror
includes: a substrate; a reflection plate which is rotatable and
reflects light; a pair of torsion springs which support opposite
ends of the reflection plate so that the reflection plate is raised
from the substrate, and acting as a rotation axis when the
reflection plate is rotationally driven; a pair of frames which are
connected to the reflection plate without connecting to the torsion
springs and are symmetrically formed with respect to the torsion
springs; frame supporting units which connect the reflection plate
and the frames; and a driving unit including moving combs disposed
on the frames and static combs disposed on the substrate and
respectively corresponding to the moving combs in order to generate
an electrostatic force.
Inventors: |
Jeong; Hee-Moon; (Yongin-si,
KR) ; Lee; Jin-ho; (Suwon-si, KR) ; Cho;
Jin-woo; (Seongnam-si, KR) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
|
Family ID: |
38106417 |
Appl. No.: |
11/408049 |
Filed: |
April 21, 2006 |
Current U.S.
Class: |
359/224.1 ;
348/E5.139; 348/E5.142; 348/E9.026 |
Current CPC
Class: |
H04N 5/7458 20130101;
H02N 1/008 20130101; Y10S 359/904 20130101; H04N 9/3129 20130101;
G02B 26/0841 20130101; H04N 5/7416 20130101 |
Class at
Publication: |
359/198 |
International
Class: |
G02B 26/08 20060101
G02B026/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 20, 2006 |
KR |
10-2006-0006273 |
Claims
1. A rotational micro mirror comprising: a substrate; a reflection
plate which is rotatable and reflects light; a pair of torsion
springs which support opposite ends of the reflection plate so that
the reflection plate is raised from the substrate, and acting as a
rotation axis when the reflection plate is rotationally driven; a
pair of frames which are connected to the reflection plate without
connecting to the torsion springs and are symmetrically formed with
respect to the torsion springs; frame supporting units which
connect the reflection plate and the frames; and a driving unit
comprising moving combs disposed on the frames and static combs
disposed on the substrate and respectively corresponding to the
moving combs in order to generate an electrostatic force.
2. The rotational micro mirror of claim 1, wherein the reflection
plate has a circular shape.
3. The rotational micro mirror of claim 1, wherein the pair of
torsion springs are installed so that the rotation axis of the
reflection plate passes through the center of volume of the
reflection plate.
4. The rotational micro mirror of claim 1, wherein the
cross-sectional areas of the torsion springs are different from one
another.
5. The rotational micro mirror of claim 4, wherein, in the torsion
springs, the cross-sectional areas of first portions which are
close to the reflection plate are larger than those of second
portions which are more distant from the reflection plate.
6. The rotational micro mirror of claim 1, wherein the frame
supporting units connect contact portions of the reflection plate
and the torsion springs with inner circumferences of the
frames.
7. The rotational micro mirror of claim 6, wherein the number of
the frame supporting units is at least four.
8. The rotational micro mirror of claim 1, wherein the frames have
curved shapes surrounding the circumference of the reflection
plate.
9. The rotational micro mirror of claim 1, wherein the moving combs
comprise a plurality of comb-fingers arranged on outer
circumferences of the frames.
10. The rotational micro mirror of claim 9, wherein the plurality
of comb-fingers of the moving combs formed on the outer
circumferences of the frames are formed perpendicular to the
rotation axis of the reflection plate.
11. The rotational micro mirror of claim 1, wherein the pair of
frames are not connected to the reflection plate through the
torsion springs.
12. The rotational micro mirror of claim 1, wherein the
cross-sectional areas of the torsion springs vary over the lengths
of the torsion springs.
13. A rotational micro mirror comprising: a substrate; a reflection
plate which is rotatable and reflects light; a pair of torsion
springs which support opposite ends of the reflection plate so that
the reflection plate is raised from the substrate, and acting as a
rotation axis when the reflection plate is rotationally driven; a
pair of frames which are connected to the reflection plate in a
manner other than through the torsion springs; and a driving unit
comprising moving combs disposed on the frames and static combs
disposed on the substrate and respectively corresponding to the
moving combs in order to generate an electrostatic force.
14. The rotational micro mirror of claim 13, wherein the pair of
frames are connected to the reflection plate at least one of
directly and through frame supporting units.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This application claims priority from Korean Patent
Application No. 10-2006-0006273, filed on Jan. 20, 2006, in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a rotational micro mirror
and, more particularly, to a micro mirror used for scanning a laser
beam in a display device such as a laser TV, and a method of
manufacturing the same.
[0004] 2. Description of the Related Art
[0005] With the advances of the multimedia era, large screen
displays are increasingly demanded, and accordingly, various kinds
of large screen display devices have been developed. A laser TV has
been suggested as a next-generation display device because of
inexpensive manufacturing costs and the possibility of
manufacturing it with a large screen that displays high resolution
images.
[0006] The laser TV includes a light scanner which scans
horizontally and vertically laser beams radiating from laser diode
modules according to red-green-blue (RGB) image signals. A micro
mirror manufactured using a micro-electro mechanical system (MEMS)
is used for the light scanner.
[0007] FIGS. 1A and 1B are plan views of conventional micro
mirrors. FIG. 2 illustrates the operation of the micro mirrors of
FIGS. 1A and 1B.
[0008] Referring to FIG. 1A and 1B, the micro mirror includes a
rotatable mirror unit 1, a pair of spring units 2 and 2' connected
to opposite ends of the mirror unit 1 to support the mirror unit 1
and act as a rotation axis when the mirror unit 1 rotates, and
moving combs 3 and static combs 4 forming a driving unit which
rotates the mirror unit 1.
[0009] The moving combs 3 and static combs 4 respectively include a
plurality of comb-fingers. The moving combs 3 may be installed in
the mirror unit 1 as illustrated in FIG. 1A or in spring units 2
and 2' as illustrated in FIG. 1B. In addition, the static combs 4
are installed in a lower portion or an upper portion of the moving
combs 3 as illustrated in FIG. 2 and the comb-fingers of the static
combs 4 are arranged to respectively alternate with the
comb-fingers of the moving combs 3.
[0010] As illustrated in FIG. 2, when first and second comb-fingers
3a and 3b of the moving combs 3 are negatively charged (-), and
first comb-fingers 4a of the static combs 4 are positively charged
(+), an electrostatic force is generated between the first
comb-fingers 3a of the moving combs 3 and the first comb-fingers 4a
of the static combs 4, and thus the mirror unit 1 is rotationally
driven, as shown with the dotted line in FIG. 2, around a spring
unit 2. When second comb-fingers 4b of the static combs 4 are
positively charged (+), the mirror unit 1 is rotationally driven in
the opposite direction. Due to the rotational driving of the mirror
unit 1, incident light is continuously and uniformly reflected in a
predetermined range to scan a scanning surface.
[0011] A driving speed of a micro mirror is related to the
resolution of a display device, and a driving angle is related to a
screen size. That is, as the driving speed of a micro mirror
increases, the resolution becomes high. As the driving angle
increases, the screen size increases. Accordingly, a laser TV with
a large screen and high resolution should have a light scanner,
that is, a micro mirror, which is rapidly driven and has a large
driving angle.
[0012] The driving speed of the micro mirror is inversely
proportional to the driving angle, and thus it is difficult to
obtain both a rapid driving speed of the micro mirror and a large
driving angle. Meanwhile, to increase the driving speed of the
micro mirror, resonant driving can be used. However, it is
difficult to match the inherent frequency of the micro mirror to
the driving frequency due to manufacturing errors, and thus
manufacturing yield of the micro mirror is low. In addition, an
additional tuning structure for adjusting the frequency may be
required.
[0013] The micro mirror of FIG. 1A has moving combs 3 on sides of
the mirror unit 1. In this structure, the distance D.sub.1 from a
rotation center of the mirror unit 1 is large, and thus the
magnitude of a rotational moment is large compared with the micro
mirror of FIG. 1B when the same number of the moving combs 3 is
used. However, the number of the moving combs 3 is limited. In
addition, when a large number of the moving combs 3 is formed, the
size of the mirror unit 1 increases, thereby increasing the moment
of inertia and decreasing the inherent frequency of the micro
mirror, and thus, a rapid driving speed cannot be obtained.
[0014] The micro mirror of FIG. 1B has the moving combs 3 formed
along spring units 2 and 2'. In this structure, the number of the
moving combs 3 can be increased, thereby decreasing the magnitude
of moment of inertia, compared with the structure of FIG. 1A.
However, the distance D.sub.2 from the center axis is short so that
a small moment is generated, and thus a sufficient driving angle is
not obtained. In addition, elastic coefficients of the spring units
2 and 2' may not be the same due to a processing error.
[0015] Since the conventional micro mirror does not have both a
rapid driving speed and a large driving angle, it is not suitable
for use in a light scanner for a laser TV having a large size and
high resolution.
SUMMARY OF THE INVENTION
[0016] The present invention provides a rotational micro mirror
having an improved structure to decrease the moment of inertia and
increase the rotational moment, thereby providing a large driving
angle.
[0017] The present invention also provides an improved structure of
the rotational micro mirror, which decreases the moment of inertia
and increases the rotational moment, and minimizes deformation due
to the rapid operation of the micro mirror so that a display device
having the rotational micro mirror provides improved images.
[0018] According to an aspect of the present invention, there is
provided a rotational micro mirror including: a substrate; a
reflection plate which is rotatable and reflects light; a pair of
torsion springs which support opposite ends of the reflection plate
so that the reflection plate is raised from the substrate, and
acting as a rotation axis when the reflection plate is rotationally
driven; a pair of frames which are connected to the reflection
plate without connecting to the torsion springs and are
symmetrically formed with respect to the torsion springs; frame
supporting units which connect the reflection plate and the frames;
and a driving unit including moving combs disposed on the frames
and static combs disposed on the substrate and respectively
corresponding to the moving combs in order to generate an
electrostatic force.
[0019] The reflection plate may have a circular shape with a
minimum area for light reflection, but the present invention is not
limited thereto.
[0020] The pair of torsion springs may be installed so that the
rotation axis of the reflection plate passes through the center of
volume of the reflection plate, and are twisted when the reflection
plate is rotationally driven. The cross-sectional areas of the
torsion springs may be different from one another. In addition, in
the torsion springs, the cross-sectional areas of first portions
which are close to the reflection plate may be larger than those of
second portions which are more distant from the reflection plate.
The different cross-sectional areas can prevent stress
concentration on contact portions of the reflection plate and the
torsion springs when the reflection plate is rotationally
driven.
[0021] The frame supporting units may connect contact portions of
the reflection plate and the torsion springs with the frames. At
least four frame supporting units may be used.
[0022] The frames may have a curved shape surrounding the
circumference of the reflection plate.
[0023] The moving combs include a plurality of comb-fingers
arranged on the outer circumference of the frame. In addition, the
comb-fingers of the moving combs may be formed perpendicular to the
rotation axis of the reflection plate, but the present invention is
not limited thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings, in which:
[0025] FIGS. 1A and 1B are plan views of conventional micro
mirrors;
[0026] FIG. 2 illustrates the operation of the micro mirrors of
FIGS. 1A and 1B;
[0027] FIG. 3 is a perspective view illustrating the configuration
of a micro mirror according to an exemplary embodiment of the
present invention; and
[0028] FIG. 4 illustrates the operation of the micro mirror of FIG.
3.
DETAILED DESCRIPTION OF ILLUSTRATIVE, NON-LIMITING EMBODIMENTS OF
THE INVENTION
[0029] Hereinafter, the present invention will be described more
fully with reference to the accompanying drawings, in which
exemplary embodiments of the invention are shown.
[0030] FIG. 3 is a perspective view illustrating a configuration of
a rotational micro mirror according to an exemplary embodiment of
the present invention. FIG. 4 illustrates the operation of the
rotational micro mirror of FIG. 3.
[0031] In the rotational micro mirror of FIG. 3, a reflection plate
10 for reflecting light has a circular shape with a minimum area
for light reflection. The reflection plate 10 is not limited to the
circular shape illustrated in FIG. 3, but the circular shape is
desirable because the moment of inertia does not increase too much
in this case. The radius of the reflection plate 10 can be adjusted
according to the light to be used.
[0032] The reflection plate 10 is rotationally driven within a
predetermined angle using a pair of torsion springs 20 and 20' as a
central axis. The pair of torsion springs 20 and 20' support the
reflection plate 10. When the reflection plate 10 is rotationally
driven, the reflection plate 10 is twisted. The torsion springs 20
and 20' should be installed so that the rotation axis of the
reflection plate 10 passes through the center of volume of the
reflection plate 10, and thus the reflection plate 10 is not
initially bent and the micro mirror operates stably when it is
rotationally driven. In FIG. 3, the cross-sectional areas of the
torsion springs 20 and 20' are different from one another. That is,
in the torsion springs 20 and 20', the cross-sectional areas of
first portions 20a and 20a' which are close to the reflection plate
10 are larger than those of second portions 20b and 20b' which are
more distant from the reflection plate 10. The different
cross-sectional areas can prevent stress concentration on contact
portions of the reflection plate 10 and the torsion springs 20 and
20' when the reflection plate 10 is rotationally driven. However,
the different cross-sectional areas of the torsion springs 20 and
20' may not be required.
[0033] The pair of frames 30 and 30' have curve shapes surrounding
the reflection plate 10, and are symmetrical with respect to the
torsion springs 20 and 20'. The pair of frames 30 and 30' are not
directly connected to the torsion springs 20 and 20', but are
connected via both sides of the reflection plate 10 and frame
supporting units 60 protruding from the reflection plate 10. The
frames 30 and 30' support moving combs 40 and transfer a driving
force to the reflection plate 10, the driving force being caused by
an electrostatic force and transferred from static combs 50 (see
FIG. 4) to the moving combs 40. In addition, portions of the frames
30 and 30' circumscribe portions of the outer circumference of the
circular reflection plate 10 so that predetermined spaces S are
formed between uncontacted portions of the outer circumference of
the reflection plate 10 and the frames 30 and 30'. The spaces S
improve an airflow to rotationally drive the reflection plate 10
smoothly.
[0034] The frame supporting units 60 protrude from the contact
portions of the reflection plate 10 and the torsion springs 20 and
20', connect the contact portions with the inner circumference of
the frames 30 and 30', and support the frames 30 and 30', thereby
providing structural stability. In FIG. 3, two frame supporting
units 60 are formed in each of the frames 30, but the present
invention is not limited thereto. For example, more than four frame
supporting units may be formed in a single frame.
[0035] The moving combs 40 include a plurality of comb-fingers. As
illustrated in FIG. 3, the plurality of comb-fingers of the moving
combs 40 are arranged on the outer circumferences of the frames 30
and 30' with a predetermined interval. Accordingly, compared with
the conventional structure, the structure according to the present
embodiment can have the moving combs 40 including more
comb-fingers, but the size of a reflection plate 10, which affects
the moment of inertia, decreases.
[0036] The static combs 50 also include a plurality of
comb-fingers. The plurality of comb-fingers of the static combs 50
are arranged in a lower portion of the moving combs 40, as
illustrated in FIG. 4, and fixed on a substrate (not illustrated).
The comb-fingers of the moving combs 40 are arranged to
respectively alternate with the comb-fingers of the static combs
50.
[0037] In the rotational micro mirror of the present embodiment, an
electrostatic force acts on the moving combs 40 formed in the
frames 30 and 30' and the static combs 50 formed to alternate with
the moving combs 40, as illustrated in FIG. 4. The electrostatic
force induces a rotational force to move the moving combs 40 around
the torsion springs 20 and 20' of the reflection plate 10. That is,
first and second comb-fingers 40a and 40b of the moving combs 40
are, for example, negatively charged (-), and first comb-fingers
50a of the static combs 50 are positively charged (+), and then an
electrostatic force is generated between the first comb-fingers 40a
of the moving combs 40 and the first comb-fingers 50a of the static
combs 50. Then, the reflection plate 10 rotates around the torsion
springs 20 and 20'. When a voltage is applied to the static combs
50 with a regular driving frequency, the reflection plate 10
repeatedly rotates with the driving frequency.
[0038] According to the present invention, there is provided a
micro mirror having a structure to decrease the moment of inertia
and increase the rotational moment.
[0039] Consistent with the present invention, there is also
provided an improved structure of the rotational micro mirror,
which decreases the moment of inertia and increases the rotational
moment, and minimizes deformation due to the rapid operation of the
micro mirror so that a laser display device having a rotational
micro mirror can display high resolution images.
[0040] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *