U.S. patent application number 15/386300 was filed with the patent office on 2018-01-04 for rotational actuator for optical device and camera module having the same.
The applicant listed for this patent is JAHWA electronics Co., Ltd.. Invention is credited to Sang Chul KIM, Doo Sik SHIN.
Application Number | 20180003915 15/386300 |
Document ID | / |
Family ID | 60786898 |
Filed Date | 2018-01-04 |
United States Patent
Application |
20180003915 |
Kind Code |
A1 |
SHIN; Doo Sik ; et
al. |
January 4, 2018 |
ROTATIONAL ACTUATOR FOR OPTICAL DEVICE AND CAMERA MODULE HAVING THE
SAME
Abstract
Disclosed is a rotational actuator for an optical device, which
includes a rotary shaft capable of freely rotating at a fixed
position; a first shape-memory alloy wire fixed in a first
direction to give a rotation moment to the rotary shaft, the first
shape-memory alloy wire making length contraction with respect to
the rotary shaft when an electric current is applied thereto; a
second shape-memory alloy wire fixed in a second direction opposite
to the first direction to give a rotation moment with respect to
the rotary shaft, the second shape-memory alloy wire making length
contraction with respect to the rotary shaft when an electric
current is applied thereto; and a control unit configured to supply
an electric current to the first shape-memory alloy wire when
rotating the rotary shaft in the first direction and supply an
electric current to the second shape-memory alloy wire when
rotating the rotary shaft in the second direction.
Inventors: |
SHIN; Doo Sik; (Gyeonggi-do,
KR) ; KIM; Sang Chul; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JAHWA electronics Co., Ltd. |
Chungcheongbuk-do |
|
KR |
|
|
Family ID: |
60786898 |
Appl. No.: |
15/386300 |
Filed: |
December 21, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 7/006 20130101;
H04N 5/2253 20130101; F03G 7/065 20130101; H04N 5/2254 20130101;
G06K 9/00604 20130101; G02B 26/007 20130101; G02B 5/208 20130101;
H04N 5/33 20130101; G06K 9/2018 20130101 |
International
Class: |
G02B 7/00 20060101
G02B007/00; G06K 9/00 20060101 G06K009/00; F03G 7/06 20060101
F03G007/06; G02B 5/20 20060101 G02B005/20; H04N 5/33 20060101
H04N005/33; H04N 5/225 20060101 H04N005/225 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 1, 2016 |
KR |
10-2016-0083741 |
Claims
1. A rotational actuator for an optical device, comprising: a
rotary shaft capable of freely rotating at a fixed position; a
first shape-memory alloy wire fixed in a first direction to give a
rotation moment to the rotary shaft, the first shape-memory alloy
wire making length contraction with respect to the rotary shaft
when an electric current is applied thereto; a second shape-memory
alloy wire fixed in a second direction opposite to the first
direction to give a rotation moment with respect to the rotary
shaft, the second shape-memory alloy wire making length contraction
with respect to the rotary shaft when an electric current is
applied thereto; and a control unit configured to supply an
electric current to the first shape-memory alloy wire when rotating
the rotary shaft in the first direction and supply an electric
current to the second shape-memory alloy wire when rotating the
rotary shaft in the second direction.
2. The rotational actuator for an optical device according to claim
1, wherein the control unit blocks power supply to the first
shape-memory alloy wire or the second shape-memory alloy wire when
the rotary shaft completely rotates in first direction or second
direction.
3. The rotational actuator for an optical device according to claim
1, wherein the first shape-memory alloy wire and the second
shape-memory alloy wire are respectively made of a single
shape-memory alloy wire and adhered to the rotary shaft at a
boundary point of the first direction and the second direction; and
the rotary shaft is electrically connected to the single
shape-memory alloy wire as a common negative electrode terminal,
and first and second independent positive electrode terminals are
respectively electrically connected to both ends of the single
shape-memory alloy wire.
4. The rotational actuator for an optical device according to claim
1, wherein the first shape-memory alloy wire and the second
shape-memory alloy wire are respectively made of a single
shape-memory alloy wire and wound on the rotary shaft by at least
one turn; and the rotary shaft is electrically connected to the
single shape-memory alloy wire as a common negative electrode
terminal, and first and second independent positive electrode
terminals are respectively electrically connected to both ends of
the single shape-memory alloy wire.
5. The rotational actuator for an optical device according to claim
1, wherein middle portions of the first shape-memory alloy wire and
the second shape-memory alloy wire are coupled to the rotary shaft
to be capable of expanding or contracting so that both ends of each
shape-memory alloy wire extend in the first direction and the
second direction, respectively; and both ends of each shape-memory
alloy wire are electrically connected to a negative electrode
terminal and first and second independent positive electrode
terminals.
6. The rotational actuator for an optical device according to claim
5, wherein the negative electrode terminal to which one of both
ends of each shape-memory alloy wire is connected is a single
common negative electrode terminal.
7. The rotational actuator for an optical device according to claim
1, further comprising a rotator fixed to the rotary shaft.
8. The rotational actuator for an optical device according to claim
7, wherein two filters having different characteristics as an
optical window are provided at the rotator.
9. The rotational actuator for an optical device according to claim
8, wherein the two filters are respectively an infrared cutoff
filter and an infrared pass filter.
10. A camera module, at which the rotational actuator for an
optical device defined in claim 1 is loaded.
11. The camera module according to claim 10, wherein the rotational
actuator for an optical device is loaded on a surface of the camera
module at which an opening is formed to allow light to pass to a
lens assembly of the camera module.
12. The camera module according to claim 11, wherein the rotary
shaft is installed at an edge of the camera module.
13. The camera module according to claim 12, wherein the first
direction and the second direction extend from the rotary shaft
with an angle of 90.degree..
14. The camera module according to claim 13, wherein the surface at
which the opening is formed has a rectangular shape, and the first
shape-memory alloy wire and the second shape-memory alloy wire
respectively extend along two edges of the rectangular surface.
15. The camera module according to claim 10, wherein the camera
module having an infrared cutoff filter and an infrared pass filter
at the rotator is used for iris recognition.
Description
CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY
[0001] The present application claims priority to Korean Patent
Application No. 10-2016-0083741 filed on Jul. 1, 2016 in the Korea
Intellectual Property Office, the disclosures of which are
incorporated herein by reference.
BACKGROUND
1. Technical Field
[0002] The present disclosure relates to a rotational actuator for
an optical device and a camera module having the same, and more
particularly, to a rotational actuator for an optical device, which
is integrally provided at a camera module mounted to a portable
terminal but is capable of rotating without giving any serious
influence on size and power consumption of the camera module, and a
camera module having the same.
2. Background Art
[0003] Generally, a camera module for taking an image is basically
loaded on a portable terminal (hereinafter, referred to as a
"portable terminal") such as a cellular phone, a smart phone, a PDA
or the like.
[0004] The camera module loaded on the portable terminal should
have a very small design, and thus at early stages, the camera
module has a deteriorated photographing function in comparison to
general digital cameras. However, recently, along with continuous
technical development, various functions such as autofocusing,
optical zooming, optical image stabilization or the like have been
added thereto so that a user may satisfactorily take images of
daily lives every time.
[0005] Such an optical adjustment function is heavily indebted to
the technical development of a small actuator which moves an
optical element. In a camera module for a portable terminal, the
small actuator technique is being developed in various ways for
improving the performance of the actuator, improving a design to
effectively dispose the small actuator in a narrow space, or the
like.
[0006] Until now, the small actuator applied to a camera module is
mostly classified into VCM (Voice Coil Motor) actuators and
piezo-electric actuators. These actuators are capable of linearly
moving a subject, because optical elements in the camera module are
mostly operated to linearly move along an optical axis for focusing
or move on a plane orthogonal to the optical axis for image
stabilization.
[0007] Meanwhile, recently, security of personal information stored
in the portable terminal has become a serious social issue. For
security of a portable terminal, it is possible to use inherent
biometric data of a user when the user accesses a home screen of
the portable terminal, accesses personal information or makes a
payment, in order to authenticate whether the user is a sincere
user of the portable terminal.
[0008] As a user authentication device included in the portable
terminal, there are generally used a voiceprint recognition device,
a fingerprint recognition device, an iris recognition device or the
like.
[0009] An iris recognition device applicable to a portable terminal
is introduced in Korean Unexamined Patent Publication No.
2002-0042004 (published on Jun. 5, 2002), entitled "an
authentication device using iris recognition". The iris recognition
device applicable to a portable terminal as mentioned above
basically includes an iris recognition chip for extracting iris
codes from an iris image taken by a camera module mounted to the
portable terminal to perform user registration or
authentication.
[0010] However, an imaging device such as a charge-coupled device
(CCD) and a complementary metal-oxide semiconductor (CMOS) applied
to the camera module of the portable terminal responds to
near-infrared ray or infrared ray with a wavelength of about 700
nm. However, the near-infrared ray or infrared ray causes crosstalk
to the imaging device to weaken color reproduction of the imaging
device and deteriorate a signal-to-noise ratio of the imaging
device. Therefore, the camera module needs an infrared cutoff
filter for blocking near-infrared ray or infrared ray.
[0011] Contrary to the above case where a general image is taken,
when an image is taken for vein recognition, iris recognition or
face recognition, the precision of recognition seriously
deteriorates under a visible light, and thus an infrared light is
required. However, since the camera module basically includes the
infrared cutoff filter as described above, even though an infrared
light is used, 90% or above of the infrared light is blocked by the
infrared cutoff filter, thereby eliminating the effect of the
infrared light. If the infrared cutoff filter is removed to solve
this problem, an image may be taken under an infrared light, but
the quality of a daylight image which is most ordinary and frequent
should be sacrificed.
[0012] In order to solve this problem, Korean Unexamined Patent
Publication No. 10-2006-0119077 (published on Nov. 24, 2006)
discloses a `portable communication terminal having an iris
recognition function`, which includes a filter unit installed at a
terminal body at the front of a camera lens and classified into an
infrared pass filter and an infrared cutoff filter, wherein a
filter suitable for a photographing mode is selected by moving the
filter unit right or left by means of clockwise/counterclockwise
rotation of a motor having a lead screw shaft or moving the filter
unit right or left while gripping a filter moving knob.
[0013] However, in Korean Unexamined Patent Publication No.
2006-0119077 (published on Nov. 24, 2006), the filter unit
classified into an infrared pass filter and an infrared cutoff
filter should be mounted separately to the terminal body, and a
motor should be provided to automatically move the filter unit
right and left. In other words, since the filter unit is not
integrated with the camera module, the number of parts and
assembling processes increases, and thus a communication terminal
manufacturer cannot easily select the filter unit. In addition, in
the current trends, the portable terminal gets thinner and thinner,
the battery becomes larger and larger, and more diverse attachments
are included in the portable terminal. Thus, it is substantially
impossible to ensure a space for mounting a separate filter
unit.
[0014] Heretofore, the necessity of an actuator for automatically
selecting a suitable filter for iris recognition or general imaging
has been described. In order to add other functions in addition to
autofocusing, optical zooming and optical image stabilization to
the camera module to follow the recent development trend of the
portable terminal, these functions should be integrated with the
camera module. However, if a VCM actuator or piezo-electric
actuator broadly used in the art is applied to the existing camera
module, the camera module has too large size to be applied to the
portable terminal. In addition, the VCM actuator and the
piezo-electric actuator need a conversion unit to give a rotation
since they are basically used for giving a linear motion.
[0015] Therefore, there is a need to develop a rotational actuator
for an optical device, which may give a rotation with a new
structure without giving an influence on the size of the camera
module.
SUMMARY
[0016] The present disclosure is directed to providing a rotational
actuator for an optical device, which is integrally provided at a
camera module mounted to a portable terminal and may give a
rotation with a new structure without giving an influence on the
size and power consumption of the camera module.
[0017] In one aspect of the present disclosure, there is provided a
rotational actuator for an optical device, comprising: a rotary
shaft capable of freely rotating at a fixed position; a first
shape-memory alloy wire fixed in a first direction to give a
rotation moment to the rotary shaft, the first shape-memory alloy
wire making length contraction with respect to the rotary shaft
when an electric current is applied thereto; a second shape-memory
alloy wire fixed in a second direction opposite to the first
direction to give a rotation moment with respect to the rotary
shaft, the second shape-memory alloy wire making length contraction
with respect to the rotary shaft when an electric current is
applied thereto; and a control unit configured to supply an
electric current to the first shape-memory alloy wire when rotating
the rotary shaft in the first direction and supply an electric
current to the second shape-memory alloy wire when rotating the
rotary shaft in the second direction.
[0018] Here, the control unit may block power supply to the first
shape-memory alloy wire or the second shape-memory alloy wire when
the rotary shaft completely rotates in first direction or second
direction.
[0019] In an embodiment of the present disclosure, the first
shape-memory alloy wire and the second shape-memory alloy wire may
be respectively made of a single shape-memory alloy wire and
adhered to the rotary shaft at a boundary point of the first
direction and the second direction, and the rotary shaft may be
electrically connected to the single shape-memory alloy wire as a
common negative electrode terminal, and first and second
independent positive electrode terminals are respectively
electrically connected to both ends of the single shape-memory
alloy wire.
[0020] In other case, in another embodiment of the present
disclosure, the first shape-memory alloy wire and the second
shape-memory alloy wire may be respectively made of a single
shape-memory alloy wire and wound on the rotary shaft by at least
one turn, the rotary shaft may be electrically connected to the
single shape-memory alloy wire as a common negative electrode
terminal, and first and second independent positive electrode
terminals may be respectively electrically connected to both ends
of the single shape-memory alloy wire.
[0021] In addition, in still another embodiment of the present
disclosure middle portions of the first shape-memory alloy wire and
the second shape-memory alloy wire may be coupled to the rotary
shaft to be capable of expanding or contracting so that both ends
of each shape-memory alloy wire extend in the first direction and
the second direction, respectively, and both ends of each
shape-memory alloy wire may be electrically connected to a negative
electrode terminal and first and second independent positive
electrode terminals.
[0022] At this time, the negative electrode terminal to which one
of both ends of each shape-memory alloy wire may be a single common
negative electrode terminal.
[0023] In such various embodiments, a rotator fixed to the rotary
shaft may be further provided.
[0024] Here, two filters having different characteristics as an
optical window may be provided at the rotator.
[0025] The two filters may be respectively an infrared cutoff
filter and an infrared pass filter.
[0026] Meanwhile, the rotational actuator for an optical device
according to various embodiments as mentioned above may be loaded
at a camera module.
[0027] In an embodiment, the rotational actuator for an optical
device may be loaded on a surface of the camera module at which an
opening is formed to allow light to pass to a lens assembly of the
camera module.
[0028] Here, in the rotational actuator for an optical device, the
rotary shaft may be installed at an edge of the camera module, and
the first direction and the second direction may extend from the
rotary shaft with an angle of 90.degree..
[0029] In addition, the surface at which the opening is formed may
have a rectangular shape, and the first shape-memory alloy wire and
the second shape-memory alloy wire may respectively extend along
two edges of the rectangular surface.
[0030] Moreover, the camera module having an infrared cutoff filter
and an infrared pass filter at the rotator may be used for iris
recognition.
[0031] The rotational actuator for an optical device according to
the present disclosure configured as above may rotate a rotary
shaft in both directions just with a simple structure for adhering
a thin shape-memory alloy wire to the rotary shaft and selectively
supplying an electric current. Therefore, the rotational actuator
may be very easily applied to a camera module included in a small
portable terminal in an integrated form.
[0032] In addition, since the wire is prepared simply without
processing a shape-memory alloy into a special shape and is just
used to make length contraction by a resistance heat, it is
possible to ensure very reliable operation.
[0033] Moreover, since the shape-memory alloy wire has a diameter
of just several ten micrometers, a sufficient resistance heat may
be generated just with a fine electric current. Therefore, the
rotational actuator has low power consumption and thus is very
suitable for a portable terminal which is sensitive to power
control.
BRIEF DESCRIPTION OF DRAWINGS
[0034] FIGS. 1A and 1B are diagrams showing a basic structure of a
rotational actuator for an optical device according to the present
disclosure to explain an operation principle thereof.
[0035] FIG. 2 is a diagram showing a rotational actuator for an
optical device according to an embodiment of the present
disclosure.
[0036] FIG. 3 is a diagram showing a rotational actuator for an
optical device according to another embodiment of the present
disclosure.
[0037] FIG. 4 is a diagram showing a rotational actuator for an
optical device according to still another embodiment of the present
disclosure.
[0038] FIG. 5 is an exploded perspective view showing that the
rotational actuator for an optical device is applied to a camera
module according to an embodiment of the present disclosure.
[0039] FIG. 6 is a perspective view showing that the rotational
actuator for an optical device, depicted in FIG. 5, is coupled to
the camera module.
DETAILED DESCRIPTION
[0040] Hereinafter, embodiments of the present disclosure will be
described in detail with reference to the accompanying
drawings.
[0041] When describing the embodiments of the present disclosure,
any known feature obviously understood by those skilled in the art
will not be explained in detail in order to avoid ambiguity of the
present disclosure. In addition, like reference symbols are donated
to like elements though they are depicted in different drawings.
Also, it should be understood that thickness of lines or sizes of
components may be exaggerated in the drawings for better
understanding and convenient explanation.
[0042] In addition, when describing components of the present
disclosure, the terms such as "first", "second", "A", "B", "(a)",
"(b)" or the like may be used. These terms are just used for
distinguishing any component from another component and are not
intended to limit essence, order, sequence or the like of the
corresponding components. When it is described that any component
is "connected", "coupled" or "united" to another component, the
component may be directly connected, coupled or united to another
component, but it is also possible that the component is be
indirectly connected, coupled or united to another component in a
state where further another component is interposed between
them.
[0043] FIGS. 1A and 1B are diagrams showing a basic structure of a
rotational actuator 10 for an optical device according to the
present disclosure to explain an operation principle thereof.
Therefore, the present disclosure is not limited to the structure
of FIGS. 1A and 1B, but various embodiments will be described
later.
[0044] The rotational actuator 10 for an optical device, shown in
FIGS. 1A and 1B, includes a rotary shaft, a first shape-memory
alloy wire 210, a second shape-memory alloy wire 220 and a control
unit 300.
[0045] The rotary shaft may freely rotate at a fixed position, and
a rotator 120, explained later, may be attached or integrated to
the rotary shaft. In other words, by means of the rotation of the
rotary shaft, the rotator 120 may be turned to a desired direction
by a desired angle.
[0046] The first and second shape-memory alloy wires 210, 220 are
used for rotating the rotary shaft to a desired direction and are
made of a shape-memory alloy. Even though the shape-memory alloy is
deformed by applying a force thereto, the shape-memory alloy
restores to its original shape instantly by applying just a little
heat thereto since it memorizes its original shape. At the present,
a titanium-nickel alloy obtained by mixing titanium and nickel at a
ratio of 1:1 and a copper-zinc-aluminum alloy containing 20 to 25%
of zinc and 4 to 6% of aluminum are available in the market.
[0047] The first shape-memory alloy wire 210 is fixed in a first
direction P1 to apply a rotation moment to the rotary shaft 100. In
other words, one end of the first shape-memory alloy wire 210 is
fixed at one point deviating from the rotation center of the rotary
shaft 100, for example at a surface of the rotary shaft 100, so
that a rotation moment is applied to the rotary shaft 100 as the
length of the first shape-memory alloy wire 210 changes.
[0048] If an electric current is applied to the first shape-memory
alloy wire 210, heat is generated by means of resistance. Due to
the heat, the first shape-memory alloy wire 210 restores to its
original shape from a deformed state, thereby making length
contraction with respect to the rotary shaft 100. Based on FIGS. 1A
and 1B, if an electric current is applied to the first shape-memory
alloy wire 210 to make length contraction, the rotary shaft 100
rotates in a counterclockwise direction.
[0049] The second shape-memory alloy wire 220 is substantially
identical to the first shape-memory alloy wire 210 in its basic
configuration. However, the second shape-memory alloy wire 220 is
fixed at a second direction P2 so that when making length
contraction, the second shape-memory alloy wire 220 rotates the
rotary shaft 100 in a direction opposite to the case where the
first shape-memory alloy wire 210 makes length contraction. In
other words, based on FIGS. 1A and 1B, if an electric current is
applied to the second shape-memory alloy wire 220 to make length
contraction, the rotary shaft 100 rotates in a clockwise
direction.
[0050] Here, the first direction P1 and the second direction P2 are
terms to indicate that the first and second shape-memory alloy
wires 210, 220 make length contraction in opposite directions based
on a direction in which a rotation moment is applied to the rotary
shaft 100. In other words, the first direction P1 and the second
direction P2 do not merely mean that the first and second
shape-memory alloy wires 210, 220 simply extend in opposite
directions.
[0051] In FIG. 1A, the first and second shape-memory alloy wires
210, 220 extend in opposite directions, but in FIG. 1B, the first
and second shape-memory alloy wires 210, 220 extend in the same
direction. In other words, the first direction P1 and the second
direction P2 are determined according to both point of actions (PA)
at which the first and second shape-memory alloy wires 210, 220 are
fixed on the rotary shaft 100 and directions in which the first and
second shape-memory alloy wires 210, 220 extend.
[0052] In addition, the length contraction of the first and second
shape-memory alloy wires 210, 220 may cause a rotation moment to
the rotary shaft 100 if one end of each of the shape-memory alloy
wires 210, 220 is fixed to the rotary shaft 100 and the other end
is fixed to any one point.
[0053] Here, the length contraction by resistance heat depends on
strain rates and entire lengths of the first and second
shape-memory alloy wires 210, 220. In other words, the absolute
contraction length of each of the first and second shape-memory
alloy wires 210, 220 is determined according to the entire length
thereof and the contraction ratio caused by heat applied
thereto.
[0054] In addition, an angle by which the rotary shaft 100 rotates
in the first direction P1 or in the second direction P2 is
determined according to the absolute contraction length of the
first and second shape-memory alloy wires 210, 220 and a distance
from the point of action (PA) to the rotation center. Therefore,
the rotation angle of the rotary shaft 100 may be designed as
desired by using three factors as above.
[0055] The control unit 300 may rotate the rotary shaft 100 in a
desired direction by controlling an electric current applied to
each of the first and second shape-memory alloy wires 210, 220. The
control unit 300 supplies an electric current to the first
shape-memory alloy wire 210 when rotating the rotary shaft 100 in
the first direction P1 and supplies an electric current to the
second shape-memory alloy wire 220 when rotating the rotary shaft
100 in the second direction P2.
[0056] In other words, the control unit 300 controls to apply an
electric current to the first and second shape-memory alloy wires
210, 220, respectively, in order to apply a rotation moment in the
first direction P1 and the second direction P2, and while applying
an electric current to any one shape-memory alloy wire 210 or 220,
the control unit 300 does not supply an electric current to the
other of the shape-memory alloy wire 220 or 210.
[0057] Therefore, when any one shape-memory alloy wire 210 or 220
makes length contraction by resistance heat, the other shape-memory
alloy wire 220 or 210 to which an electric current is not applied
is deformed to expand due to the length contraction, the expanded
shape-memory alloy wire 220 or 210 to which an electric current is
not applied is prepared for next length contraction. Such expansion
and contraction occurs alternately and oppositely at both
shape-memory alloy wires 210, 220 when the rotary shaft 100 repeats
rotation.
[0058] Here, if the rotary shaft 100 is completely rotated in the
first direction P1 or the second direction P2, the control unit 300
may block the supply of electric current to the first shape-memory
alloy wire 210 or the second shape-memory alloy wire 220.
Accordingly, if the rotary shaft 100 rotated in one direction keeps
the rotated state until an electric current is supplied to the
second shape-memory alloy wire 220 or the first shape-memory alloy
wire 210.
[0059] The rotational actuator 10 for an optical device according
to the present disclosure has many advantages.
[0060] First, just with a simple structure for adhering the first
and second thin shape-memory alloy wires 210, 220 to the rotary
shaft 100 and supplying an electric current thereto, the rotary
shaft 100 may be rotated in both directions. Therefore, the
rotational actuator may be very easily applied to a camera module
included in a small portable terminal in an integrated form.
[0061] In addition, since the wire is prepared simply without
processing a shape-memory alloy into a special shape and is just
used to make length contraction by a resistor heat, it is possible
to ensure very reliable operation.
[0062] Moreover, since the shape-memory alloy wire 200 has a
diameter of just several ten micrometers, a sufficient resistor
heat may be generated just with a fine electric current. Therefore,
the rotational actuator has low power consumption and thus is very
suitable for a portable terminal which is sensitive to power
control.
[0063] FIG. 2 is a diagram showing the rotational actuator 10 for
an optical device according to an embodiment of the present
disclosure, which operates based on the above principle. Here, the
control unit 300 is not depicted in FIG. 2 as well as in FIGS. 3
and 4 explained later.
[0064] In the embodiment depicted in FIG. 2, the first shape-memory
alloy wire 210 and the second shape-memory alloy wire 220 are made
of a single shape-memory alloy wire 200, and are adhered to the
rotary shaft 100 at a boundary point of the first direction P1 and
the second direction P2. In other words, the shape-memory alloy
wire 200 connected in a single wire is functionally separated or
distinguished into the first shape-memory alloy wire 210 and the
second shape-memory alloy wire 220 based on the point adhered to
the rotary shaft 100.
[0065] In addition, the rotary shaft 100 is electrically connected
to the first and second shape-memory alloy wires 210, 220 as a
common negative electrode terminal (or, a ground terminal) 400, and
independent positive electrode terminals 510, 520 are respectively
electrically connected to both ends of the single shape-memory
alloy wire 200. The electric currents applied to both ends of the
single shape-memory alloy wire 200 are selectively supplied under
the control of the control unit 300.
[0066] In the depicted embodiment, the first and second
shape-memory alloy wires 210, 220 are made of the single
shape-memory alloy wire 200, and the single shape-memory alloy wire
200 is adhered and electrically connected to the rotary shaft 100
serving as a common negative electrode terminal 400. Therefore, an
electric current supplied to any one end of the shape-memory alloy
wire 200 does not flow to the other side based on the point adhered
to the rotary shaft 100.
[0067] FIG. 3 is a diagram showing a rotational actuator 10 for an
optical device according to another embodiment of the present
disclosure.
[0068] The rotational actuator 10 for an optical device as shown in
FIG. 3 is identical to the embodiment of FIG. 2 in the point that
the first shape-memory alloy wire 210 and the second shape-memory
alloy wire 220 are made of the single shape-memory alloy wire 200,
but the shape-memory alloy wire 200 is not adhered to one point at
the surface of the rotary shaft 100 but is wound at least one turn
around the rotary shaft 100, different from the embodiment of FIG.
2.
[0069] In other words, instead of the configuration where the
shape-memory alloy wire 200 is fixed to the rotary shaft 100 by
means of welding or the like, in this embodiment, the shape-memory
alloy wire 200 is wound around the rotary shaft 100 by at least one
turn to ensure a sufficient frictional force so that the change of
length of the shape-memory alloy wire 200 is converted into a
rotational motion of the rotary shaft 100. A stress may be
accumulated at the adhered portion of the shape-memory alloy wire
200 due to repeated operations of the rotary shaft 100, which may
break the shape-memory alloy wire 200. The embodiment of FIG. 2
solves this problem and also allows the shape-memory alloy wire 200
to be conveniently coupled to the rotary shaft 100.
[0070] In addition, the rotary shaft 100 is electrically connected
to the single shape-memory alloy wire 200 as a common negative
electrode terminal 400, and first and second independent positive
electrode terminals 510, 520 are respectively electrically
connected to both ends of the single shape-memory alloy wire 200,
identical to the former embodiment of FIG. 2.
[0071] FIG. 4 is a diagram showing a rotational actuator 10 for an
optical device according to still another embodiment of the present
disclosure.
[0072] In the embodiment of FIG. 4, the first shape-memory alloy
wire 210 and the second shape-memory alloy wire 220 are made of
separate shape-memory alloy wires physically divided from each
other. Further, a middle portion of each of the shape-memory alloy
wires 210, 220 is coupled to the rotary shaft 100 to be capable of
expanding or contracting, and both ends of each of the shape-memory
alloy wires 210, 220 extend in the first direction P1 and the
second direction P2, respectively.
[0073] In other words, as shown in FIG. 4, two rings 110 are formed
at a surface of the rotary shaft 100, and the first shape-memory
alloy wire 210 and the second shape-memory alloy wire 220 are
inserted into the rings 110, respectively. The rings 110 allow the
first and second shape-memory alloy wires 210, 220 to give a
rotation moment to the rotary shaft 100. The first and second
shape-memory alloy wires 210, 220 are hooked by the rings 110 but
not adhered (or, fixed) thereto, and thus the portions hooked at
the rings 110 may also be expanded or contracted (or, change the
length) without limitation.
[0074] Moreover, in the embodiment of FIG. 4, it is also important
that both ends of each of the shape-memory alloy wires 210, 220
extend in the first direction P1 and the second direction P2. Since
the positive electrode terminals 510, 520 and the negative
electrode terminal 400 are respectively electrically connected to
both ends of each of the shape-memory alloy wires 210, 220, the
entire length of each of the shape-memory alloy wires 210, 220
increases about twice in comparison to the embodiments of FIGS. 2
and 3. As described above, the absolute length contracted by the
resistance heat is determined depending on a strain rate and an
entire length of the first and second shape-memory alloy wires 210,
220, and a rotation angle of the rotary shaft 100 is determined
depending on an absolute contraction length of the first and second
shape-memory alloy wires 210, 220 and a distance from the point of
action (PA) to the rotation center. Therefore, in the embodiment of
FIG. 4, the rotation angle of the rotary shaft 100 may be greatly
increased within a limited narrow space.
[0075] Since the arrangements and fixed points of the first and
second shape-memory alloy wires 210, 220 are different from those
of the embodiments of FIGS. 2 and 4, the rotary shaft 100 may not
be used as a common negative electrode. Therefore, both ends of
each of the shape-memory alloy wires 210, 220 are electrically
connected to the first and second positive electrode terminals 510,
520, independent from the negative electrode terminal 400. At this
time, if any one of both ends of each of the shape-memory alloy
wires 210, 220 is connected to the single common negative electrode
terminal 400, the number of terminals may be reduced by one.
[0076] FIG. 5 is an exploded perspective view showing that the
rotational actuator 10 for an optical device is applied to a camera
module 20 according to an embodiment of the present disclosure, and
FIG. 6 is a perspective view showing that the rotational actuator
10 for an optical device, depicted in FIG. 5, is coupled to the
camera module 20.
[0077] Here, the rotational actuator 10 for an optical device
according to the embodiment of FIG. 2 is applied to the camera
module 20 of FIGS. 5 and 6, but this is just an example, and it
should be understood that the rotational actuator 10 for an optical
device according to the embodiments of FIGS. 3 and 4 may also be
applied thereto.
[0078] Referring to FIGS. 5 and 6, a rotator 120 is further
provided at the rotary shaft 100 of the rotational actuator 10 for
an optical device, described above. The rotator 120 is a portion
moving together when the rotary shaft 100 moves (or, rotates), and
the rotator 120 is used as a component for actually giving any
optical effect to the camera module 20. The rotary shaft 100 and
the rotator 120 may be prepared separately and the coupled to each
other as shown in the figures or may also be integrally prepared as
a single component.
[0079] One of optical effects given by the rotator 120 is a
filtering function for adjusting a wavelength band of light put
into a lens assembly (or, a lens barrel) 26 of the camera module
20. The rotator 120 having this function is provided with two
filters having different characteristics as an optical window. In
other words, any one of two filters provided at the rotator 120 may
be arranged to block an opening 24 formed in a top cover 22 of the
camera module 20 so that the wavelength band of light put into the
lens assembly 26 of the camera module 20 is adjusted. A filter
located at the front of the opening 24 of the top cover 22 is
selected by rotating the rotary shaft 100, and in an actual
implementation, a camera program (application) for controlling the
camera module 20 and obtaining image data may send an instruction
to the control unit 300 of the rotational actuator 10 for an
optical device to automatically select a filter according to an
imaging mode.
[0080] In an embodiment, two filters provided at the rotator 120
may be respectively an infrared cutoff filter 122 and an infrared
pass filter 124. As a preparation for iris recognition (or, vein
recognition) for user registration or authentication and general
imaging, the rotator 120 may be controlled so that the infrared
pass filter 124 for iris recognition (or, vein recognition) or the
infrared cutoff filter 122 for general imaging is located at the
front of the opening 24 of the top cover 22, thereby ensuring an
optimal imaging result.
[0081] Though not shown in the figures, in another embodiment,
holes with different diameters may be formed in the rotator 120,
instead of providing filters to the rotator 120. The holes formed
in the rotator 120 may serve as a kind of iris diaphragm. In other
words, by providing an iris diaphragm adjusted into two stages to
the camera module 20, the depth of field may be differently set.
Since it is substantially not yet found that a physical iris
diaphragm is provided at the camera module 20 loaded at a portable
terminal, the rotational actuator 10 for an optical device
according to the present disclosure may give a good solution
thereto.
[0082] Meanwhile, FIGS. 5 and 6 show an embodiment in which the
rotational actuator 10 for an optical device according to the
present disclosure is loaded at the camera module 20.
[0083] As shown in the figures, the rotational actuator 10 for an
optical device according to the present disclosure may be loaded on
a surface of the camera module 20 in which the opening 24 is formed
to allow light to move into the lens assembly 26, namely on the top
cover 22. Since the rotational actuator 10 for an optical device
according to the present disclosure is composed of just simple and
small components, namely the first and second shape-memory alloy
wires 210, 220 and the rotary shaft 100, the rotational actuator 10
may be applied to an existing camera module 20, whose design is
already completed, without any great difficulty.
[0084] In other words, without changing the inner configuration of
the camera module 20, the rotational actuator 10 of the present
disclosure may be applied to an existing camera module 20 through a
simple design change just by installing the first and second
shape-memory alloy wires 210, 220 and the rotary shaft 100 on the
top cover 22 and then connecting the positive electrode terminals
510, 520 and the negative electrode terminal (a ground terminal)
400 thereto to supply an electric current to the first and second
shape-memory alloy wires 210, 220. In addition, the control unit
300 for operating the rotational actuator 10 for an optical device
may be configured just by modifying programs of a control unit
which is already provided at the camera module 20 or the portable
terminal.
[0085] Here, in the rotational actuator 10 for an optical device,
the rotary shaft 100 may be installed at an edge of the camera
module 20, and the first direction P1 and the second direction P2
in which rotation moments are applied to the rotary shaft 100
oppositely may extend from the rotary shaft 100 with an angle of
90.degree.. This is because the camera module 20 is mostly designed
with a hexagonal shape in which the surface (the top cover) having
the opening 24 has a rectangular shape.
[0086] In addition, in this arrangement, the first shape-memory
alloy wire 210 and the second shape-memory alloy wire 220 may
respectively extend along two edges of the rectangular shape of the
top cover 22 to have sufficient lengths. This is because a
sufficient angle for operating the rotator 120 may be ensured when
the first and second shape-memory alloy wires 210, 220 are as long
as possible.
[0087] The present disclosure has been described and illustrated in
detail. However, it should be understood by those skilled in the
art that the present disclosure can be modified in various ways
within the scope of the present disclosure. Therefore, the scope of
the present disclosure should be defined by the appended claims and
their equivalents.
* * * * *