|
Digital Camera Patent Abstract
Provided is a hand-shake correction module for a digital camera,
which has a small volume and small operational load when moved.
The hand-shake correction module includes a base plate; a first
sliding member which moves in a first axis direction with respect
to the base plate; a second sliding member including an image pickup
device, the second sliding member being movable with respect to
the first sliding member in a second axis direction perpendicular
to the first axis; and a pressing means which generates a magnetic
force preventing the first sliding member and the second sliding
member from being separated from the base plate.
Digital Camera Patent Claims
1. A hand-shake correction module for a camera, comprising:a base
plate;a first sliding member that is movable in a first axis direction
with respect to the base plate;a second sliding member that is movable
in a second axis direction with respect to the base plate, the second
axis direction being generally perpendicular to the first axis direction;an
image pickup device coupled with one of the first sliding member
and the second sliding member for movement in the first and second
axis directions; anda means for generating a magnetic force that
presses the first and second sliding members toward the base plate
to prevent the first and second sliding members from being separated
from the base plate in a third axis direction that is generally
perpendicular to the first and second axis directions.
2. The hand-shake correction module of claim 1 wherein the means
for generating a magnetic force comprises:a first magnetic or magnetizable
member coupled to at least one of the first sliding member and the
second sliding member; anda second magnetic or magnetizable member
coupled to the base plate.
3. The hand-shake correction module of claim 2 wherein the first
magnetic or magnetizable member is a permanent magnet.
4. The hand-shake correction module of claim 3 wherein the second
magnetic or magnetizable member is a second permanent magnet configured
to have a polarity opposite the first permanent magnet.
5. The hand-shake correction module of claim 3 wherein the second
magnetic or magnetizable member is a metal plate.
6. The hand-shake correction module of claim 5 wherein the base
plate comprises a material selected from the group consisting of
paramagnetic materials and nonmagnetic materials.
7. The hand-shake correction module of claim 2 wherein a length
of the second magnetic or magnetizable member along the first axis
direction is greater than a length of the first magnetic or magnetizable
member along the first axis direction.
8. The hand-shake correction module of claim 2 wherein the second
magnetic or magnetizable member is a permanent magnet.
9. The hand-shake correction module of claim 8 wherein the base
plate comprises a material selected from the group consisting of
paramagnetic materials and nonmagnetic materials.
10. The hand-shake correction module of claim 8 wherein the first
magnetic or magnetizable member is a metal plate.
11. The hand-shake correction module of claim 1 further comprising:a
first driving means coupled with one of the first and second sliding
members, the first driving means configured to move said one of
the first and second sliding members in one of the first and second
axis directions; anda second driving means coupled with the other
one of the first and second sliding members, the second driving
means configured to move said other one of the first and second
sliding members in the other one of the first and second axis directions.
12. The hand-shake correction module of claim 11 wherein at least
one of the first and second driving means is a piezo electric motor.
13. The hand-shake correction module of claim 1 further comprising
a shift sensing means that senses an amount of movement of the image
pickup device along the first and second axis directions with respect
to the base plate.
14. The hand-shake correction module of claim 13 wherein the shift
sensing means comprises:a hall sensor coupled to the base plate;
anda magnet coupled to one of the first and second sliding members.
15. A hand-shake correction module for a camera, the hand-shake
correction module comprising:a base plate including a first magnetic
or magnetizable member;a first sliding member movably coupled with
the base plate for movement in a first axis direction; anda second
sliding member including a second magnetic or magnetizable member,
the second sliding member being movably coupled with the first sliding
member for movement in a second axis direction that is generally
perpendicular to the first axis direction,wherein the first and
second magnetic or magnetizable members cooperate to prevent the
first and second sliding members from being separated from the base
plate in a third axis direction that is generally perpendicular
to the first and second axis directions.
16. The hand-shake correction module of claim 15 further comprising:a
first driving means coupled with one of the first and second sliding
members, the first driving means configured to move said one of
the first and second sliding members in one of the first and second
axis directions; anda second driving means coupled with the other
one of the first and second sliding members, the second driving
means configured to move said other one of the first and second
sliding members in the other one of the first and second axis directions.
17. The hand-shake correction module of claim 16 wherein at least
one of the first and second driving means is a piezo electric motor.
18. The hand-shake correction module of claim 15 further comprising
a shift sensing means that senses an amount of movement of the image
pickup device along the first and second axis directions with respect
to the base plate.
19. The hand-shake correction module of claim 18 wherein the shift
sensing means comprises:a hall sensor coupled to the base plate;
anda magnet coupled to one of the first and second sliding members.
20. A camera comprising:a housing;a base plate coupled to the housing,
the base plate including a first magnetic or magnetizable member;a
first sliding member movably coupled with the base plate for movement
in a first axis direction; anda second sliding member including
a second magnetic or magnetizable member, the second sliding member
being movably coupled with the first sliding member for movement
in a second axis direction that is generally perpendicular to the
first axis direction,wherein the first and second magnetic or magnetizable
members cooperate to prevent the first and second sliding members
from being separated from the base plate in a third axis direction
that is generally perpendicular to the first and second axis directions.
Digital Camera Patent Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001]This application claims the benefit of Korean Patent Application
No. 10-2006-0054889, filed on Jun. 19, 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 hand-shake correction
module for a digital camera, and more particularly, to a hand-shake
correction module for a digital camera, which reduces the influence
of hand-shake when taking pictures.
[0004]2. Description of the Related Art
[0005]As digital still cameras and digital video cameras have become
ubiquitous, consumers' demands for high quality photographs and
moving images have increased. In particular, when a CMOS (complementary
metal oxidized semiconductor) sensor is used as an image pickup
device, instead of a CCD (charge coupled device), picture resolution
is degraded due to hand-shake. To address this problem, a hand-shake
correction module is being increasingly used in digital still cameras
and video cameras.
[0006]Hand shake correction can be performed using lens shifting,
image pickup shifting, or lens barrel shifting. Image pickup shifting
is schematically illustrated in FIG. 1. Referring to FIG. 1, a conventional
hand-shake correction system 1 includes a base plate 2, a slider
3, and an image pickup device base 4. The image pickup device base
4 is equipped with an image pickup device, (not illustrated), for
example, a CCD.
[0007]The image pickup device base 4 is installed on the slider
3 and can move along a Y-axis direction with respect to the slider
3. The slider 3 is installed on the base plate 2 and can move along
an X-axis direction with respect to the base plate 2. Therefore,
the image pickup device can move along the X-axis and Y-axis directions
with respect to the base plate 2. The slider 3 and the image pickup
device base 4 are driven along the X-axis and Y-axis directions
by separate driving means (not illustrated) such as motors, actuators
or other devices known in the art. A spring 5 is installed between
a protrusion 3a of the slider 3 and a protrusion 2a of the base
plate 2. The spring 5 provides an elastic force that prevents the
slider 3 and the image pickup device base 4 from separating from
the base plate 2 in a Z-axis direction.
[0008]The base plate 2 included in the hand-shake correction system
1 of FIG. 1 may be installed in a barrel (not illustrated) of an
optical system of a digital camera and thus, moves with the digital
camera. When a user of the digital camera takes a picture and the
hand of the user shakes in the X-axis or Y-axis directions, the
image pickup device base 4 moves in an opposite direction of the
hand-shake motion to compensate for the hand-shake. However, because
of the spring 5, the conventional hand shake correction system has
several disadvantages as explained below.
[0009]First, a driving means of the slider 3 provides a driving
force F (FIG. 2) to the slider 3. Therefore, when the slider 3 moves
to the right in the X-axis direction with respect to the base plate
2, the spring 5 applies an elastic force K in the opposite direction
of the driving force F in the X-axis direction. Thus, when the spring
5 is short, the elastic force K is larger, and accordingly, the
operation of the driving means is obstructed. Second, since the
elastic force K varies with the moving distance of the slider 3,
the load of the spring 5 applied to the driving means of the slider
3 also varies, and thus, it is difficult to achieve linear control
of the driving means of the slider 3.
[0010]To address these problems, the length of the spring 5 should
be sufficiently long. However, when the spring 5 is long the height
of the hand-shake correction system 1 increases. In addition, in
order to attach a long spring 5 between the protrusions 2a and 3a,
the height h (FIG. 1) may become greater than the average height
of the hand-shake correction system 1. To this end, the inner space
for placing other elements in the hand-shake correction system may
be limited.
SUMMARY OF THE INVENTION
[0011]A hand shake correction module for a camera is provided.
An embodiment of the hand shake correction module includes: a base
plate; a first sliding member that is movable in a first axis direction
with respect to the base plate; a second sliding member including
an image pickup device, the second sliding member being movable
with respect to the first sliding member in a second axis direction
being generally perpendicular to the first axis; and a pressing
means which prevents the first sliding member and the second sliding
member from being separated from the base plate.
[0012]An example pressing means may include a first magnetic or
magnetizable member connected to the first sliding member; and a
second magnetic or magnetizable member connected to the base plate
such that a magnetic force between the first and second members
presses the first sliding member to a side of the base plate in
a third axis direction that is generally perpendicular to the first
and second axis directions. In addition, the first and second members
are configured such that they are substantially aligned with each
other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013]FIG. 1 is a perspective view schematically illustrating a
conventional hand-shake correction system;
[0014]FIG. 2 is a diagram schematically illustrating that a spring
mounted between a base plate and a slider in the conventional hand-shake
correction system of FIG. 1;
[0015]FIG. 3 is an exploded view of an example hand-shake correction
module for a digital camera according to an embodiment of the present
invention;
[0016]FIG. 4 is a perspective view illustrating an assembled state
of the hand-shake correction module of FIG. 3;
[0017]FIG. 5 is a diagram schematically illustrating operation
of a pressing means of the hand-shake correction module of FIGS.
3 and 4; and
[0018]FIG. 6 is a side cut-away view of an example digital camera
partially showing internal components including the hand-shake correction
module of FIGS. 3 and 4.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019]Hereinafter, the present invention will be described more
fully with reference to the accompanying drawings, in which exemplary
embodiments of the invention are shown.
[0020]FIG. 3 is an exploded view of an example hand-shake correction
module 100 according to an embodiment of the present invention and
FIG. 4 is a perspective view illustrating an assembled state of
the example hand-shake correction module 100 illustrated in FIG.
3.
[0021]The hand-shake correction module 100 illustrated in FIGS.
3 and 4 includes a base plate 10, a first sliding member 20, a second
sliding member 30, a first driving means 23, a second driving means
33, a pressing means and a shift sensing means 62. The base plate
10 provides support for components of the hand-shake correction
module 100. The sliding member 20 is coupled to the base plate 10
and can move in a first direction (e.g., the X-axis direction) with
respect to the base plate 10.
[0022]The first driving means 23 is coupled to a portion 10b of
the base plate 10 to be able to move in the X-axis direction. The
driving shaft of the first driving means 23 is disposed in a V-shaped
groove 20b of the first sliding member 20. After the driving shaft
of the first driving means 23 is disposed in the V-shaped groove
20b of the first sliding member 20, a V-shaped cover 55 is disposed
on the driving shaft of the first driving means 23 and the V-shaped
cover 55 is pressed to a side of the V-shaped groove 20b using a
spring 56 (e.g., a torsion spring as shown).
[0023]The first driving means 23 may be, for example, a piezo-electric
motor, actuator or any driving device known in the art that is capable
of effecting reciprocal (i.e., back and forth) linear or rotational
motion. Therefore, the first driving means 23 moves the first sliding
member 20 in the X-axis direction with respect to the base plate
10.
[0024]The second sliding member 30 is coupled with the lower center
of the first sliding member 20 and can move in the Y-axis direction
with respect to the first sliding member 20. The second driving
means 33 is coupled to a portion 30a of the second sliding member
30 to be able to move in a second direction (e.g., the Y-axis direction)
that is generally perpendicular to the first direction. The driving
shaft of the second driving means 33 is disposed in a V-shaped groove
20c of the first sliding member 20. After the driving shaft of the
second driving means 33 is disposed into the V-shaped groove 20c
of the first sliding member 20, a V-shaped cover 57 is disposed
on the driving shaft of the second driving means 33 and the V-shaped
cover 57 is pressed to a side of the V-shaped groove 20c using a
spring 58 (e.g., a torsion spring as shown). The second driving
means 33 may be, for example, for example, a piezo-electric motor,
actuator or any driving device known in the art that is capable
of effecting reciprocal (i.e., back and forth) linear or rotational
motion. In some embodiments, the second driving means 33 may be
substantially similar to the first driving means 23, but the second
driving means 33 is not limited as such. The second driving means
33 moves the second sliding member 30 in the Y-axis direction with
respect to the first sliding member 20.
[0025]An image pickup device 41, for example, a CCD (charge coupled
device) or a CMOS (complementary metal oxidized semiconductor) sensor,
is disposed on the second sliding member 30 (e.g., in the center
thereof) and an IR filter (not illustrated) may be interposed between
the image pickup device 41 and lenses (not illustrated).
[0026]As further shown in FIG. 3, the image pickup device 41 is
coupled to an image pickup device assembly 40. In addition, a printed
circuit board 50 is configured on the image pickup device assembly
40 opposite the side including the image pickup device 41. The printed
circuit board 50 and the image pickup device assembly 40 may be
coupled together using connecting members 51 (e.g., fasteners such
as screws, bolts, etc.) as shown. Since the first sliding member
20 can move in the X-axis direction with respect to the base plate
10 and the second sliding member 30 can move in the Y-axis direction
with respect to the first sliding member 20, the image pickup device
41 can move with two degrees of freedom (in the X-axis and Y-axis
directions) with respect to the base plate 10.
[0027]First ball bearings 21 and first bearing plates 22 as well
as second ball bearings 31 and second bearing plates 32 may be interposed
between moving members of the module 100 as shown. In this way,
a space between moving members can be secured and friction between
the moving members can be reduced. In more detail, the first ball
bearing 21 and the first bearing plate 22 are interposed between
the first sliding member 20 and the second sliding member 30. Although
two first ball bearings 21 and two first bearing plates 22 are shown,
fewer or additional first ball bearings 21 and first bearing plates
22 may be provided. Similarly, the second ball bearing 31 and the
second bearing plate 32 are interposed between the second sliding
member 30 and the base plate 10. Although two second ball bearings
31 and two second bearing plates 32 are shown, fewer or additional
second ball bearings 31 and second bearing plates 32 may be provided.
In this way, the first sliding member 20 and the second sliding
member 30 can smoothly move in the X-axis and Y-axis directions
with respect to the base plate 10. As can be appreciated, the number
of the ball bearings and the bearing plates can vary and other devices
or parts (e.g., plastic members with inherent lubricity) may be
employed to facilitate relative movement of the first sliding member
20, the second sliding member 30 and the base plate 10.
[0028]As an example of the pressing means according to an embodiment
of the present invention, a first member being a magnet 25 is coupled
to one side portion 20a of the first sliding member 20 and a second
member being a magnetic guide plate 12 is coupled to one side portion
10a of the base plate 10. Thus, a magnetic attraction force is developed
between the first and second members (i.e., the magnetic guide plate
12 and the magnet 25) of the pressing means. Accordingly, the first
sliding member 20 and the second sliding member 30 cannot be easily
separated from the base plate 10. Although the magnet 25 is coupled
to the first sliding member 20 and the magnetic guide plate 12 is
coupled to the base plate 10, it should be appreciated that the
magnet 25 and magnetic guide plate 12 may be configured oppositely.
Furthermore, it should be appreciated that the magnet 25 may be
any one of the following magnetic members including a permanent
magnet, an electromagnet and a magnetized member. Similarly, it
should be appreciated that the magnetic guide plate 12 may be any
member known in the art that may be attracted to or otherwise cooperate
with the magnet 25 such as, for example, a permanent magnet, an
electromagnet, a magnetized member and a magnetizable (e.g., ferric)
member.
[0029]The one side portion 20a of the first sliding member 20 to
which the magnet 25 is coupled and the one side portion 10a of the
base plate 10 to which the magnetic guide plate 12 is coupled may
be generally aligned with each other. Also, as can be appreciated,
the magnetic guide plate 12 and the base plate 10 are made of different
materials (e.g., a magnetic material and non-magnetic material or
vice versa, respectively) such that the base plate 10 does not interfere
with attraction between the magnet 25 and the magnetic guide plate
12. In one example, the base plate 10 may comprise a paramagnetic
material such as aluminum.
[0030]As shown in FIG. 3, the length of the magnet 25 in the X-axis
direction is shorter than the length of the magnetic guide plate
12 in the X-axis direction. In addition, the length of the magnetic
guide plate 12 may be sufficiently long to allow the magnet 25 to
be disposed in the upper part of the magnetic guide plate 12, in
the range where the first sliding member 20 moves in the X-axis
direction. Due to magnetic attraction force between the magnet 25
and the magnetic guide plate 12, the first sliding member 20 and
the second sliding member 30 can be coupled to the base plate 10.
Therefore, the first sliding member 20 and the second sliding member
30 can be prevented from being separated from the base plate 10
in the Z-axis direction, for example in the case of an external
impact or vibrations.
[0031]FIG. 5 is a diagram schematically illustrating that a driving
load due to the pressing means is substantially insignificant when
the first sliding member 20 of the hand-shake correction module
of FIG. 3 moves in the X-axis direction. Referring to FIG. 5, although
the magnetic attraction force between the magnet 25 and the magnetic
guide plate 12 acts vertically and the first sliding member 20 moves
in the X-axis direction with respect to the base plate 10, the magnet
25 is substantially always disposed above the magnetic guide plate
12. Therefore, when the first sliding member 20 moves in the X-axis
direction with respect to the base plate 10 according to a driving
force F from the first driving means 23, an opposing load in the
X-axis direction hardly occurs in the present hand-shake correction
module 100 compared to the case of the conventional hand-shake correction
module of FIG. 2. Accordingly, a thorough motion control of the
image pickup device 41 (FIG. 3) is possible and an operational reliability
can be also improved.
[0032]In addition, when the magnet 25 and the magnetic guide plate
12 are fixed to the first sliding member 20 and the base plate 10,
respectively, installation of other elements is not limited in the
hand-shake correction module according to an embodiment of the present
invention as compared to the case of the conventional hand-shake
correction module 1 illustrated in FIG. 1. Furthermore, as can be
appreciated from FIG. 6, the space within camera housing 90 is conserved
for placing other elements due to the relatively compact configuration
of the hand-shake correction module 100.
[0033]As another example of the pressing means of the present invention,
the magnet 25 may be coupled to the portion 10a of the base plate
10 whereas the magnetic guide plate 12 may be coupled to the portion
20a of the first sliding member 20. In this case, the first sliding
member 20 may be a formed of a non-magnetic, paramagnetic (e.g.,
aluminum) or non-magnetizable (e.g., plastic) material. As described
above, the magnet 25 and the magnetic guide plate 12 are disposed
facing each other. The length of the magnetic guide plate 12 in
the X-axis direction may be longer than the length of the magnet
25. As can be appreciated, in this example the magnet 25 and magnetic
guide plate 12 are configured oppositely from the illustrated hand-shake
correction module 100 of FIG. 3.
[0034]As another example of the pressing means of the present invention,
a first member of the pressing means may be the magnet 25 that may
be coupled to the first sliding member portion 20a and the second
member of the pressing means may be a magnet, magnetic or magnetized
guide plate 12 (i.e., the plate 12 may be made of a magnet-type
material substantially similar to the magnet 25) that may be coupled
to the base plate 10a. In this example, it should be appreciated
that the facing surfaces of the first magnet 25 and the second magnet
12 should have opposite polarities such that they attract each other.
For example, the first magnet 25 may be configured such that its
lower surface defines a South pole, whereas the second magnet 12
is configured such that its upper surface defines a North pole.
Alternatively, the first magnet 25 may be configured such that its
lower surface defines a North pole, whereas the second magnet 12
is configured such that its upper surface defines a South pole.
[0035]A shift sensing means is provided on the right side of the
base plate 10 and is configured to sense a moving distance by which
the second sliding member 30 (and image pickup device 41) moves
in the X-axis and Y-axis directions with respect to the base plate
10. As an example of the shift sensing means, a hall sensor 62 may
be used in cooperation with a magnet 63. As is known in the art,
the hall sensor 62 operates based on the principle that a current
(or voltage) amplitude that is output from the hall sensor 62 is
changed according to a strength of a magnetic field to which the
hall sensor 62 is subjected or otherwise disposed in.
[0036]As illustrated in FIG. 3, the magnet 63 is disposed above
the hall sensor 62. The magnet 63 is coupled with the second sliding
member 30. When the second sliding member 30 moves in the X-axis
and Y-axis directions with respect to the base plate 10, the magnet
63 also moves. Therefore, a position of the magnet 63 with respect
to the hall sensor 62 varies according to a movement of the image
pickup device 41 in the X-axis and Y-axis directions with respect
to the base plate 10 during hand-shake correction. In this way,
since the strength of magnetic field changes and the change in current
(or voltage) amplitude output from the hall sensor 62 may be sensed,
determined or otherwise detected, for example by a controller (not
shown) in communication with the hall sensor 62, the shift sensing
means thus facilitates sensing of a moving distance by which the
image pickup device 41 moves in the X-axis and Y-axis directions
with respect to the base plate 10. The measured data can be used
as a feedback signal to control the first and second driving means
23 and 33.
[0037]Referring now to FIG. 6, an example digital camera is provided
that includes the hand-shake correction module 100. As illustrated
in FIG. 6, the base plate 10 of the hand-shake correction module
100 may be fixed to a portion of the body or housing 90 of the digital
camera. Thus, when the digital camera moves due to hand shake, the
base plate 10 also moves relative to the first and second sliding
members 20, 30, the circuit board 50 and the image pickup device
40 (FIGS. 3 and 4). On the other hand, hand-shake sensing means
(not shown), for example, gyro sensors, accelerometers and the like
are installed in the digital camera to detect the amount of motion
of the body or housing 90 of the digital camera (or the base plate
10), for example, the rotation amount in the yaw and pitch directions.
[0038]A device, for example a processor or controller (not shown)
of the digital camera, using measured data from one or more of the
hand-shake sensing means (not shown) and the shift sensing means
may calculate the amount of movement in the X-axis and Y-axis directions
of the second sliding member 30 to compensate for the hand shake
of the digital camera. Then, the first driving means 23 and the
second driving means 33 drive the first sliding member 20 and the
second sliding member 30, respectively, and the second sliding member
30 is moved in the X-axis and Y-axis directions. Here, since the
foregoing described and illustrated pressing means is used, driving
control of the first driving means 23 is precise and thus, an operational
reliability is improved. Therefore, the image pickup device 41 moves
in the opposite direction of the hand shake so that clear images
can be photographed.
[0039]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. |