U.S. patent application number 13/717252 was filed with the patent office on 2013-07-04 for camera module and auto focusing method of camera module.
This patent application is currently assigned to LG INNOTEK CO., LTD.. The applicant listed for this patent is LG Innotek Co., Ltd.. Invention is credited to Seong Min LEE, Sang Ok PARK.
Application Number | 20130169832 13/717252 |
Document ID | / |
Family ID | 48694536 |
Filed Date | 2013-07-04 |
United States Patent
Application |
20130169832 |
Kind Code |
A1 |
PARK; Sang Ok ; et
al. |
July 4, 2013 |
CAMERA MODULE AND AUTO FOCUSING METHOD OF CAMERA MODULE
Abstract
A camera module and an auto focusing method of the camera module
are provided, the camera module including a VCM (Voice Coil Motor)
including a rotor including a lens distanced from a reference
plane, in a case no driving signal is applied, a posture detection
sensor determining a posture of the VCM; an ISP (Image Signal
Processor) generating a driving signal for driving the VCM using an
optimum focus value of the lens calculated by an auto focus
algorithm in response to a posture of the VCM determined by the
posture detection sensor, an image sensor changing lens-passed
light to a digital signal, and a controller controlling the VCM,
the posture detection sensor, the image signal processor and the
image sensor.
Inventors: |
PARK; Sang Ok; (Seoul,
KR) ; LEE; Seong Min; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG Innotek Co., Ltd.; |
Seoul |
|
KR |
|
|
Assignee: |
LG INNOTEK CO., LTD.
Seoul
KR
|
Family ID: |
48694536 |
Appl. No.: |
13/717252 |
Filed: |
December 17, 2012 |
Current U.S.
Class: |
348/208.2 ;
348/357 |
Current CPC
Class: |
H04N 5/2257 20130101;
G02B 7/28 20130101; H04N 5/23212 20130101; G02B 7/09 20130101; G03B
13/36 20130101 |
Class at
Publication: |
348/208.2 ;
348/357 |
International
Class: |
H04N 5/232 20060101
H04N005/232 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 29, 2011 |
KR |
10-2011-0145806 |
Dec 29, 2011 |
KR |
10-2011-0145807 |
Claims
1. An auto focusing method of a camera module, the method
comprising: determining a posture of a rotor, in a case a driving
current is not applied; determining a non-driving section of the
rotor where the rotor is not driven even if a driving current is
applied in response to the posture of the rotor, and determining a
driving section of the rotor where driving is started by the
driving current; and skipping an auto focusing of the non-driving
section and performing an auto focusing of the driving section.
2. The method of claim 1, wherein, at the step of determining the
posture of the rotor, the rotor is brought into contact with a
reference plane by elasticity force, in a case no driving current
is applied.
3. The method of claim 1, wherein, at the step of determining the
posture of the rotor, the posture of the rotor is directed by a
gyro sensor.
4. The method of claim 1, wherein, at the step of determining the
posture of the rotor, the posture of the rotor is any one of a down
posture where a lens mounted at the rotor faces downwards, a side
posture where an optical axis of the lens is side by side with a
ground, and an up posture where the lens is opposite to the
ground.
5. The method of claim 4, wherein a length of the non-driving
section increases in the order of the down posture, the side
posture and the up posture.
6. The method of claim 1, wherein the step of performing the auto
focusing at the driving section includes measuring a focus value of
the lens mounted at the rotor at the driving section, determining a
focus adjustment state by calculating a DOFV (Difference of Focus
Value) which is a difference value between a current focus value of
the lens and a previous focus value, while increasing or decreasing
the driving current as much as a predetermined step and moving the
rotor, and fixing the rotor, in a case it is determined as a result
of determination that the lens is on an optimum focus position.
7. The method of claim 1, wherein, at the step of determining the
posture of the rotor, the rotor is distanced from the reference
plane by an elastic member, in a case the driving current is not
applied.
8. The method of claim 7, the method further comprises tightly
contacting the rotor to the reference plane by applying an initial
driving current to perform the auto focusing operation, between the
step of determining the posture of the rotor and the step of
determining the driving section and the non-driving section of the
rotor.
9. The method of claim 7, wherein the non-driving section is a
section not drivable from the reference plane even if the driving
current is applied.
10. An auto focusing method of a camera module, the method
comprising: determining a posture of a rotor, in a case a driving
current is not applied; selecting any one of a plurality of auto
focus algorithms in response to the posture of the rotor; and
skipping an auto focusing of the non-driving section of the rotor
where the rotor is not driven even if a driving current is applied
in response to the selected auto focus algorithm, and performing
the auto focus from a driving section of the rotor where the rotor
is driven by the driving current.
11. The method of claim 10, wherein, at the step of determining the
posture of the rotor, the posture of the rotor is directed by a
gyro sensor.
12. The method of claim 11, wherein the posture of the rotor is any
one of a down posture where a lens mounted at the rotor faces
downwards, a side posture where an optical axis of the lens is side
by side with a ground, and an up posture where the lens is opposite
to the ground.
13. The method of claim 10, wherein the auto focus algorithm
includes a first auto focus algorithm in response to the down
posture, a second auto focus algorithm in response to the side
posture, and a third auto focus algorithm in response to the up
posture.
14. The method of claim 10, wherein the step of performing the auto
focusing includes measuring a focus value of the lens mounted at
the rotor at the driving section, determining a focus adjustment
state by calculating a DOFV (Difference of Focus Value) which is a
difference value between a current focus value of the lens and a
previous focus value, while increasing or decreasing the driving
current as much as a predetermined step and moving the rotor, and
fixing the rotor, in a case it is determined as a result of
determination that the lens is on an optimum focus position.
15. The method of claim 10, wherein, at the step of determining the
posture of the rotor, the rotor is distanced from the reference
plane by an elastic member, in a case the driving current is not
applied.
16. The method of claim 15, the method further comprises tightly
contacting the rotor to the reference plane by applying an initial
driving current to perform the auto focusing operation, between the
step of determining the posture of the rotor and the step of
selecting one of the auto focus algorithms.
17. A camera module, the camera module comprising: a VCM (Voice
Coil Motor) including a rotor including a lens distanced from a
reference plane, in a case no driving signal is applied; a posture
detection sensor determining a posture of the VCM; an ISP (Image
Signal Processor) generating a driving signal for driving the VCM
using an optimum focus value of the lens calculated by an auto
focus algorithm in response to a posture of the VCM determined by
the posture detection sensor; an image sensor changing lens-passed
light to a digital signal; and a controller controlling the VCM,
the posture detection sensor, the image signal processor and the
image sensor.
18. The camera module of claim 17, wherein the rotor of the VCM
drives the rotor including the lens distanced from the reference
plane to a direction or a bi-direction in a case no driving signal
is applied.
19. The camera module of claim 17, wherein the auto focus algorithm
is formed in the number corresponding to the posture of the
VCM.
20. The camera module of claim 17, wherein the auto focus algorithm
calculates the optimum focus value only at the driving section
where the rotor is driven by the driving current, and does not
calculate the optimum focus value at a non-driving section where
the rotor is not driven even if the driving current is applied to
the VCM.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119 of Korean Patent Application Nos. 10-2011-0145806, filed
Dec. 29, 2011, and 10-2011-0145807, filed Dec. 29, 2011, which are
hereby incorporated by reference in their entirety.
BACKGROUND
[0002] 1. Field of the invention
[0003] The present disclosure relates to a camera module configured
to be driven to one direction or to a bi-direction, and an auto
focusing method of a camera module.
[0004] 2. Description of Related Art
[0005] Recently, a mobile phone embedded with a super small digital
camera and a tablet PC has been developed. A conventional super
small digital camera used on a mobile phone has suffered from a
disadvantage of disablement to adjust a gap between a lens and an
image sensor changing an outside light to a digital image or a
digital video (moving image). However, recently, a lens driving
device, such as a VCM (Voice Coil Motor) capable of adjusting a gap
between an image sensor and a lens, has been developed to obtain a
digital image or a digital video that is more improved and advanced
than that of a conventional super small digital camera.
[0006] Generally, a VCM (Voice Coil Motor) applied to a camera
module is mounted therein with a rotor mounted with a lens, where
the rotor vertically moves upwards from a base to adjust a gap
between an image sensor arranged at a rear surface of the base and
a lens of the camera. Recently, a bi-directional VCM has been
developed capable of accomplishing an auto focusing by floating a
rotor of the VCM from a base and moving the rotor downwards or
upwards.
[0007] A conventional VCM is configured such that an elastic member
depresses a rotor for contact with a base when no driving signal is
applied. A rotor of a conventional bi-directionally driven VCM has
an approximately 30 .mu.m-50 .mu.m displacement depending on
self-weight of the rotor and posture of the VCM.
[0008] However, the rotor according to the conventional
bi-directionally driven VCM is disadvantageous in that, although
the rotor has a displacement depending on the posture of the VCM,
and even if no driving signal is applied, the rotor includes a
non-driving section, the auto focus operation is performed by auto
focusing algorithm not reflected with the displacement, thereby
taking lots of time for auto focusing and consuming lot of
currents.
BRIEF SUMMARY
[0009] The present invention is directed to provide a camera module
configured to determine a displacement of a rotor depending on
posture of a VCM having a bi-directionally driven rotor, and to
determine a non-driving section where the rotor is not driven even
if a driving signal is applied, skipping an auto focusing at the
non-driving section to thereby shorten an auto focusing time, and
an auto focusing method of a camera module.
[0010] The present invention is also directed to provide a camera
module configured to determine a displacement of a rotor depending
on posture of a VCM, and to determine a non-driving section where
the rotor is not driven even if a driving signal is applied,
skipping an auto focusing at the non-driving section to thereby
shorten an auto focusing time, and an auto focusing method of a
camera module.
[0011] Technical problems to be solved by the present disclosure
are not restricted to the above-mentioned descriptions, and any
other technical problems not mentioned so far will be clearly
appreciated from the following description by skilled in the
art.
[0012] In one general aspect of the present invention, there is
provided an auto focusing method of a camera module, the method
comprising: determining a posture of a rotor, in a case a driving
current is not applied; determining a non-driving section of the
rotor where the rotor is not driven even if a driving current is
applied in response to the posture of the rotor, and determining a
driving section of the rotor where driving is started by the
driving current; and skipping an auto focusing of the non-driving
section and performing an auto focusing of the driving section.
[0013] In another general aspect of the present disclosure, there
is provided an auto focusing of a camera module, the method
comprising: determining a posture of a rotor, in a case a driving
current is not applied; selecting any one of a plurality of auto
focus algorithms in response to the posture of the rotor; and
skipping an auto focusing of the non-driving section of the rotor
where the rotor is not driven even if a driving current is applied
in response to the selected auto focus algorithm, and performing
the auto focus from a driving section of the rotor where the rotor
is driven by the driving current.
[0014] In still another general aspect of the present disclosure,
there is provided a camera module, the camera module comprising: a
VCM (Voice Coil Motor) including a rotor including a lens distanced
from a reference plane, in a case no driving signal is applied; a
posture detection sensor determining a posture of the VCM; an ISP
(Image Signal Processor) generating a driving signal for driving
the VCM using an optimum focus value of the lens calculated by an
auto focus algorithm in response to a posture of the VCM determined
by the posture detecting sensor; an image sensor changing
lens-passed light to a digital signal; and a controller controlling
the VCM, the posture detection sensor, the image signal processor
and the image sensor.
[0015] The VCM according to the present disclosure has an
advantageous effect in that a displacement of a rotor is determined
depending on posture of a VCM having a bi-directionally driven
rotor, and a non-driving section is determined where the rotor is
not driven even if a driving signal is applied, and an auto
focusing is skipped at the non-driving section to thereby shorten
an auto focusing time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In the drawings, the width, length, thickness, etc. of
components may be exaggerated or reduced for the sake of
convenience and clarity. Furthermore, throughout the descriptions,
the same reference numerals will be assigned to the same elements
in the explanations of the figures, and explanations that duplicate
one another will be omitted. Now, a voice coil motor according to
the present disclosure will be described in detail with reference
to the accompanying drawings.
[0017] The teachings of the present disclosure can be readily
understood by considering the following detailed description in
conjunction with the accompanying drawings, in which:
[0018] FIG. 1 is a block diagram illustrating a camera module
according to a first exemplary embodiment of the present
disclosure;
[0019] FIG. 2 is a schematic cross-sectional view illustrating a
VCM of FIG. 1;
[0020] FIG. 3 is a cross-sectional view illustrating a side posture
of a VCM of FIG. 2;
[0021] FIG. 4 is a cross-sectional view illustrating a down posture
of a VCM of FIG. 2;
[0022] FIG. 5 is a flowchart illustrating an auto focusing method
of a camera module according to a first exemplary embodiment of the
present disclosure;
[0023] FIG. 6 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at an `up` posture;
[0024] FIG. 7 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at a `side`
posture;
[0025] FIG. 8 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at a `down`
posture;
[0026] FIG. 9 is a flowchart illustrating an auto focusing method
of a camera module according to another exemplary embodiment of the
present disclosure;
[0027] FIG. 10 is a flowchart illustrating an auto focusing method
of a camera module according to a second exemplary embodiment of
the present disclosure;
[0028] FIG. 11 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at an `up` posture;
[0029] FIG. 12 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at `side` posture;
[0030] FIG. 13 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at `down` posture;
and
[0031] FIG. 14 is a flowchart illustrating an auto focusing method
of a camera module according to a third exemplary embodiment of the
present disclosure.
DETAILED DESCRIPTION
[0032] Advantages and features of the present disclosure may be
understood more readily by reference to the following detailed
description of exemplary embodiments and the accompanying drawings.
Detailed descriptions of well-known functions, configurations or
constructions are omitted for brevity and clarity so as not to
obscure the description of the present disclosure with unnecessary
detail. Thus, the present disclosure is not limited to the
exemplary embodiments which will be described below, but may be
implemented in other forms.
[0033] The meaning of specific terms or words used in the
specification and claims should not be limited to the literal or
commonly employed sense, but should be construed or may be
different in accordance with the intention of a user or an operator
and customary usages. Therefore, the definition of the specific
terms or words should be based on the contents across the
specification.
[0034] Now, exemplary embodiments of the present disclosure will be
explained in detail together with the figures.
First Exemplary Embodiment
[0035] FIG. 1 is a block diagram illustrating a camera module
according to a first exemplary embodiment of the present
disclosure, and FIG. 2 is a schematic cross-sectional view
illustrating a VCM of FIG. 1.
[0036] Referring to FIGS. 1 and 2, a camera module (800) includes a
VCM (Voice Coil Motor, 100) driven to one direction, a posture
detection sensor (200), an auto focus algorithm (300), an ISP
(Image Signal Processor, 400), an image sensor (500) and a
controller (600).
[0037] Referring to FIG. 2, the VCM (100) performs an auto focusing
operation by driving a lens to one direction. That is, a lens
mounted on the VCM (100) is moved to a direction ascending from a
base (110, described later), and performs the auto focusing
operation between the lens and the image sensor (500) during the
moving process. The VCM (100) includes a base (110), a stator
(120), a rotor (130), an elastic member (140) and a cover
(150).
[0038] The base takes a shape of a plate centrally formed with an
opening passing light, and functions as a bottom stopper of the
rotor (130). The base (110) may be arranged at a rear surface or at
a side distanced from the rear surface with the image sensor (500).
The image sensor (500) converts light focused through the lens of
the rotor (130) to a digital image or a video. The stator (120) is
fixed to an upper surface of the base (110), and includes a first
driving unit (125) generating a magnetic field. The stator (120) is
formed therein with an accommodation space.
[0039] The first driving unit (125) in an exemplary embodiment of
the present disclosure may include a coil formed by winding a long
wire insulated by an insulation resin to generate a magnetic field
in response to a current, for example. Alternatively, the first
driving unit (125) may include a magnet generating a magnetic
field. The first driving unit (125) of the stator (120) in an
exemplary embodiment of the present disclosure includes a coil.
[0040] The rotor (130) is arranged inside the stator (120), and
includes a lens (135). The rotor (130) is mounted at an external
surface thereof with a second driving unit (138) generating a
magnetic field.
[0041] In a case the first driving unit (125) of the stator (120)
includes a coil in an exemplary embodiment of the present
disclosure, the second driving unit (138) of the rotor (130) may
include a magnet. Alternatively, in a case the first driving unit
(125) of the stator (120) includes a magnet, the second driving
unit (138) of the rotor (130) may include a coil. The second
driving unit (138) of the rotor (130) in an exemplary embodiment of
the present disclosure includes a magnet, for example.
[0042] The elastic member (140) is fixed at one side to the rotor
(130), and is fixed to the stator (120) at the other side opposite
to the one side, and elastically supports the rotor (130). In an
exemplary embodiment of the present disclosure, the elastic member
(140) may include a first elastic member (143) formed at a bottom
surface of a periphery of the rotor (130), and a second elastic
member (146) formed at an upper surface of the periphery of the
rotor (130). The elastic member (140) causes the rotor (130) to
contact an upper surface of the base (110), in a case no driving
signal is applied to the first driving unit (125) of the stator
(120) or the second driving unit (138) of the rotor (130).
[0043] That is, the elastic member (140) provides a force to the
rotor (130) to a direction facing the base, in a case no driving
signal is applied to the first driving unit (125) of the stator
(120) or the second driving unit (138) of the rotor (130). Thus, in
an exemplary embodiment of the present disclosure, an
electromagnetic force greater than an elasticity force of the
elastic member (140) or a self-weight of the rotor (130) is needed
to allow the rotor (130) to float from the base (110).
[0044] The cover (150) is fixed to the base (110), and wraps the
stator (120) and the rotor (130). The cover (150) functions as an
upper stopper stopping the rotor (130).
[0045] Referring to FIG. 1 again, the posture detection sensor
(200) outputs a sensing signal by determining a posture of the VCM
(100). In an exemplary embodiment of the present disclosure, the
posture detection sensor (200) may include a gyro sensor detecting
a direction of gravity, for example. The posture detection sensor
(200) including the gyro sensor senses three postures of the VCM
(100), for example. Of course, although the posture detection
sensor (200) can sense three or more postures of the VCM (100), the
posture detection sensor (200) in an exemplary embodiment of the
present disclosure is explained to sense three postures, i.e., an
`up` posture, a `side` posture and a `down` posture, for
convenience sake.
[0046] FIG. 3 is a cross-sectional view illustrating a side posture
of a VCM of FIG. 2, and FIG. 4 is a cross-sectional view
illustrating a down posture of a VCM of FIG. 2.
[0047] Referring to FIGS. 3 and 4, the VCM (100) includes an `up`
posture as in FIG. 2, a `side` posture as in FIG. 3, and a `down`
posture as in FIG. 4.
[0048] The "up posture" illustrated in FIG. 2 is formed by an
optical axis of the lens (135) of the rotor (130) of the VCM (100)
being arranged to a direction perpendicular to a ground, and may be
defined as a posture by the base (110) being arranged in opposition
to the ground. The `side posture` illustrated in FIG. 3 is formed
by an optical axis of the lens (135) of the rotor (130) of the VCM
(100) being arranged to a direction parallel with a ground, and may
be defined as a posture by the base (110) being arranged
perpendicular to the ground. Furthermore, the `down posture`
illustrated in FIG. 4 is formed by an optical axis of the lens
(135) of the rotor (130) of the VCM (100) being arranged to a
direction perpendicular to a ground, and may be defined as a
posture by the cover (150) being arranged in opposition to the
ground.
[0049] The auto focus algorithm (300) is electrically connected to
the ISP (400). The auto focus algorithm (300) outputs a detection
signal by detecting an optimum focus value of the VCM (100) in
response to a distance to an object in order to realize an accurate
auto focusing and a quick response time of the auto focusing. The
auto focus algorithm (300) may be formed in a shape of an algorithm
inside the ISP (400), or may be independently used or separately
used from the ISP (400).
[0050] Particularly, in an exemplary embodiment of the present
disclosure, the auto focus algorithm (300) outputs a detection
signal by detecting an optimum focus value between the lens (135)
of the rotor (130) of the VCM (100) and the image sensor (500) in
response to the abovementioned postures of the VCM (100) determined
by the posture detection sensor (200). The auto focus algorithm
(300) may be formed in the number corresponding to the number of
postures of the VCM (100), for example.
[0051] The ISP (400) outputs a driving signal for driving the VCM
(100) in response to the detection signal outputted by the auto
focus algorithm (300), and the driving signal outputted by the ISP
(400) is provided to the VCM (100) through a driving unit (not
shown), where the rotor (130) of the VCM (100) is driven in
response to the driving signal.
[0052] Referring to FIG. 1 again, the controller (500) is connected
to the VCM (100), the posture detection sensor (200), the auto
focus algorithm (300), the ISP (Image Signal Processor, 400) and
the image sensor (500) via a data bus and/or a control bus.
[0053] Hereinafter, an auto focusing method of a camera module will
be illustrated and explained with reference to the accompanying
drawings, using a VCM contacted, by a rotor, to a base by an
elastic member, in a case no driving signal is applied.
[0054] FIG. 5 is a flowchart illustrating an auto focusing method
of a camera module according to a first exemplary embodiment of the
present disclosure.
[0055] Referring to FIGS. 1 and 5, in order to perform the auto
focusing of a camera module, a step of determination is first
performed on what type of posture the rotor is currently taking, in
a case no driving current is applied to the VCM (100) (S10). The
posture of the VCM (100) may be realized by the posture detection
sensor (200) such as a gyro sensor, for example.
[0056] The posture detection sensor (200) outputs mutually
different sensing signals in response to the postures of the VCM
(100), e.g., the `up` posture, the `side` posture and the `down`
posture of the VCM (100). In a case the posture of the VCM (100) is
determined by the posture detection sensor (200), a `non-driving
section` and a `driving section` of the rotor (130) of the VCM
(100) corresponding to the posture of the VCM (100) are determined
by the ISP (400) and the auto focus algorithm (300) (S20).
[0057] Hereinafter, the `non-driving section` is defined as a
section where the rotor (130) is not driven even if a driving
signal is applied to the VCM (100), and the `driving section` is
defined as a section where the rotor (130) is driven by a driving
signal applied to the VCM (100). Now, the non-driving section and
the driving section of the VCM (100) will be illustrated and
explained with reference to FIGS. 6, 7 and 8.
[0058] FIG. 6 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at an `up` posture.
[0059] Referring to FIG. 6, an electromagnetic force greater than
the self-weight of the rotor (130) and the elasticity force of the
elastic member (140) is required to drive the rotor (130) of the
VCM (100), because the VCM (100) is arranged in an `up` posture.
Thus, the rotor (130) is not driven by a current less than A [mA]
in FIG. 6, such that a current section less than A [mA] is a
non-driving section where the rotor (130) is not driven, where the
auto focus operation is not realized due to the rotor (130) not
being operated.
[0060] Meanwhile, under a current greater than A [mA], an
electromagnetic force driving the rotor (130) is greater than the
self-weight of the rotor (130) and the elasticity force of the
elastic member (140) to drive the rotor (130), whereby a current
section greater than A [mA] is a driving section where the rotor
(130) can be driven, where the auto focus operation can be
implemented because the rotor (130) is driven.
[0061] FIG. 7 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at a `side`
posture.
[0062] Referring to FIG. 7, an electromagnetic force greater than
the self-weight of the rotor (130) and the elasticity force of the
elastic member (140) is required to drive the rotor (130) of the
VCM (100), because the VCM (100) is arranged in a `side` posture.
Thus, the rotor (130) is not driven by a current less than B [mA]
(where, B is smaller than A) in FIG. 7, such that a current section
less than B [mA] is a non-driving section where the rotor (130) is
not driven, where the auto focus operation is not realized due to
the rotor (130) not being operated.
[0063] In the exemplary embodiment of the present disclosure, the
non-driving section of VCM (100) arranged in the `side` posture of
FIG. 7 is smaller than the non-driving section of VCM (100)
arranged in the `up` posture of FIG. 6. That is, the VCM (100)
arranged in `side` posture is driven by a smaller current than that
of the VCM (100) arranged in `up` posture.
[0064] Meanwhile, in a case a current greater than B [mA] is
provided in FIG. 7, an electromagnetic force driving the rotor
(130) is greater than the self-weight of the rotor (130) and the
elasticity force of the elastic member (140) to drive the rotor
(130), whereby a current section greater than B [mA] is a driving
section where the rotor (130) can be driven, where the auto focus
operation is now implemented, because the rotor (130) is
driven.
[0065] FIG. 8 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at a `down`
posture.
[0066] Referring to FIG. 8, an electromagnetic force greater than
the self-weight of the rotor (130) and the elasticity force of the
elastic member (140) is required to drive the rotor (130) of the
VCM (100), because the VCM (100) is arranged in a `down` posture.
Thus, the rotor (130) is not driven by a current less than C [mA]
(where, C is smaller than B) in FIG. 8, such that a current section
less than C [mA] is a non-driving section where the rotor (130) is
not driven, where the auto focus operation is not realized due to
the rotor (130) not being operated.
[0067] In the exemplary embodiment of the present disclosure, the
non-driving section of VCM (100) arranged in the `down` posture of
FIG. 8 is smaller than the non-driving section of VCM (100)
arranged in the `side posture of FIG. 7. That is, the VCM (100)
arranged in `down` posture is driven by a smaller current than that
of the VCM (100) arranged in `side` posture.
[0068] Meanwhile, in a case a current greater than C [mA] is
provided in FIG. 8, an electromagnetic force driving the rotor
(130) is greater than the self-weight of the rotor (130) and the
elasticity force of the elastic member (140) to drive the rotor
(130), whereby a current section greater than C [mA] is a driving
section where the rotor (130) can be driven, where the auto focus
operation is now implemented, because the rotor (130) is
driven.
[0069] In FIGS. 6, 7 and 8, the VCM (100) in the up posture, the
VCM (100) in the side posture and the VCM (100) in the down posture
respectively have the non-driving section and the driving section
in common. That is, the VCM (100) commonly has the non-driving
section and the driving section regardless of posture, where the
auto focus operation is not realized at the non-driving section due
to the rotor (130) not working, and the auto focus operation is
realized only at the driving section due to the rotor (130)
working.
[0070] Referring to FIG. 7 again, the posture of the VCM (100) is
determined at S10, and the non-driving section and the driving
section are determined (judged) by the ISP (400) and the auto focus
algorithm (300) in response to the posture of the VCM (100) at
S20.
[0071] In a case the posture of the VCM (100) is determined to
determine the non-driving section and the driving section of the
VCM (100), the auto focus operation to the non-driving section by
the auto focus algorithm (300) is skipped to start the auto focus
operation from the driving section. In a case the auto focus
operation to the non-driving section by the auto focus algorithm
(300) is skipped to start the auto focus operation from the driving
section, a time required to implement the auto focus operation can
be greatly reduced over the implementation of the auto focus
operation starting from the non-driving section.
[0072] To be more specific, a focus value of the lens mounted on
the rotor (130) is measured by the image sensor in the driving
section determined by the posture of the VCM (100) for implementing
the auto focus operation. In a case the focus value is not an
optimum focus value, a current on the VCM (100) is increased or
decreased as much as a predetermined step to move the rotor (130),
and a DOFV (Difference of Focus Value), which is a difference value
between a current focus value and a previous focus value is
calculated to determine a focus adjustment state.
[0073] As a result of the determination, if the focus value is an
optimum focus value, the rotor (130) is fixed to a current
position, and the image sensor is used to convert an outside light
to an image or a video.
[0074] Although the exemplary embodiment of the present disclosure
has illustrated and explained that the posture of the VCM is
determined by gyro sensor, the non-driving section of the rotor is
skipped, and an auto focusing function is implemented using one
auto focus algorithm performing the auto focusing operation from
the driving section of the rotor, alternatively, the auto focusing
function may be implemented using a plurality of auto focus
algorithms in response to the posture of the VCM.
[0075] To be more specific, referring to FIGS. 1 and 9, in order to
implement the auto focusing operation, in a case a driving current
is not applied from the camera module, a posture of the rotor (130)
contacted to the base (100) by the elastic member (140), which is a
reference plane, is first determined by using a position detection
sensor such as a gyro sensor (S40).
[0076] Successively, one auto focus algorithm is selected from a
plurality of auto focus algorithms formed in number corresponding
to the posture of the rotor (130) of the VCM (100) (S50). An auto
focusing operation of non-driving section of the rotor (130)
despite the application of the driving current is skipped by the
selected auto focus algorithm, and the auto focusing operation is
performed from the driving section of the rotor driven by the
driving current, and an auto focusing operation is performed within
a shortened period of time over the auto focusing operation of the
non-driving section (S60).
[0077] As apparent from the foregoing, the auto focusing operation
of non-driving section of the rotor (130) despite the application
of the driving current is skipped, and the auto focusing operation
is performed only from the driving section of the rotor driven by
the driving current, whereby auto focusing time can be
advantageously shortened and a current consumption at the
non-driving section is reduced to reduce the power consumption.
Second Exemplary Embodiment
[0078] FIG. 10 is a flowchart illustrating an auto focusing method
of a camera module according to a second exemplary embodiment of
the present disclosure.
[0079] Referring to FIGS. 1 and 10, a step of determining what
posture is currently taken by the VCM (100) is implemented in order
to perform the auto focusing of the camera module (S10). The
posture of the VCM (100) may be realized by the posture detection
sensor (200) such as a gyro sensor.
[0080] The posture detection sensor (200) outputs mutually
different sensing signals in response to the postures of the VCM
(100), e.g., the `up` posture, the `side` posture and the `down`
posture of the VCM (100). In a case the posture of the VCM (100) is
determined by the posture detection sensor (200), the auto focus
algorithm (300) applies an initial driving signal to contact the
rotor (130) to an upper surface of the base (110) (S15).
[0081] In a case the rotor (130) is contacted to an upper surface
of the base (110), a `non-driving section` and a `driving section`
of the rotor (130) of the VCM (100) corresponding to the posture of
the VCM (100) are determined by the ISP (400) and the auto focus
algorithm (300) (S20).
[0082] Hereinafter, the `non-driving section` is defined as a
section where the rotor (130) is not driven even if a driving
signal is applied to the VCM (100), and the `driving section` is
defined as a section where the rotor (130) is driven by a driving
signal applied to the VCM (100). Now, the non-driving section and
the driving section of the VCM (100) will be illustrated and
explained with reference to FIGS. 6, 7 and 8.
[0083] FIG. 11 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at an `up` posture.
[0084] Referring to FIG. 11, an electromagnetic force greater than
the self-weight of the rotor (130) and the elasticity force of the
elastic member (140) is required to drive the rotor (130) of the
VCM (100), because the VCM (100) is arranged in an `up` posture.
Thus, the rotor (130) is not driven by a current less than A [mA]
in FIG. 11, such that a current section less than A [mA] is a
non-driving section where the rotor (130) is not driven, where the
auto focus operation is not realized due to the rotor (130) not
being operated.
[0085] Meanwhile, under a current greater than A [mA], an
electromagnetic force driving the rotor (130) is greater than the
self-weight of the rotor (130) and the elasticity force of the
elastic member (140) to drive the rotor (130), whereby a current
section greater than A [mA] is a driving section where the rotor
(130) can be driven, where the auto focus operation can be now
implemented because the rotor (130) is driven.
[0086] FIG. 12 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at side posture.
[0087] Referring to FIG. 12, an electromagnetic force greater than
the self-weight of the rotor (130) and the elasticity force of the
elastic member (140) is required to drive the rotor (130) of the
VCM (100), because the VCM (100) is arranged in a `up` posture.
Thus, the rotor (130) is not driven by a current less than B [mA]
(where, B is smaller than A) in FIG. 12, such that a current
section less than B [mA] is a non-driving section where the rotor
(130) is not driven, where the auto focus operation is not realized
due to the rotor (130) not being operated.
[0088] The VCM (100) arranged in `side` posture is driven by a
smaller current than that of the VCM (100) arranged in `up`
posture.
[0089] Meanwhile, in a case a current greater than B [mA] is
provided as shown in FIG. 12, an electromagnetic force driving the
rotor (130) is greater than the self-weight of the rotor (130) and
the elasticity force of the elastic member (140) to drive the rotor
(130), whereby a current section greater than B [mA] is a driving
section where the rotor (130) can be driven, where the auto focus
operation is now implemented, because the rotor (130) is
driven.
[0090] FIG. 13 is a graph illustrating a current-distance
characteristic in a case a VCM of FIG. 1 is at down posture.
[0091] Referring to FIG. 13, an electromagnetic force greater than
the self-weight of the rotor (130) and the elasticity force of the
elastic member (140) is required to drive the rotor (130) of the
VCM (100), because the VCM (100) is arranged in a `down` posture.
Thus, the rotor (130) is not driven by a current less than C [mA]
(where, C is smaller than B) in FIG. 13, such that a current
section less than C [mA] is a non-driving section where the rotor
(130) is not driven, where the auto focus operation is not realized
due to the rotor (130) not being operated.
[0092] In the exemplary embodiment of the present disclosure, the
VCM (100) arranged in `down` posture is driven by a smaller current
than that of the VCM (100) arranged in `side` posture.
[0093] Meanwhile, in a case a current greater than C [mA] is
provided as shown in FIG. 13, an electromagnetic force driving the
rotor (130) is greater than the self-weight of the rotor (130) and
the elasticity force of the elastic member (140) to drive the rotor
(130), whereby a current section greater than C [mA] is a driving
section where the rotor (130) can be driven, where the auto focus
operation is now implemented, because the rotor (130) is
driven.
[0094] In FIGS. 11, 12 and 13, the VCM (100) in the up posture, the
VCM (100) in the side posture and the VCM (100) in the down posture
respectively have the non-driving section and the driving section
in common. That is, the VCM (100) commonly has the non-driving
section and the driving section regardless of posture, where the
auto focus operation is not realized at the non-driving section due
to the rotor (130) not working, and the auto focus operation is
realized only at the driving section due to the rotor (130)
working.
[0095] Referring to FIG. 12 again, the posture of the VCM (100) is
determined at S10, the rotor (130) is brought into contact with the
upper surface of the base (110), and the non-driving section and
the driving section are determined (judged) by the ISP (400) and
the auto focus algorithm (300) in response to the posture of the
rotor (130) of the VCM (100) at S20.
[0096] In a case the posture of the rotor (130) of the VCM (100) is
determined to determine the non-driving section and the driving
section of the VCM (100), the auto focus operation to the
non-driving section by the auto focus algorithm (300) is skipped to
start the auto focus operation from the driving section (S30). In a
case the auto focus operation to the non-driving section by the
auto focus algorithm (300) is skipped to start the auto focus
operation from the driving section, a time required to implement
the auto focus operation can be greatly reduced over the
implementation of the auto focus operation starting from the
non-driving section.
[0097] To be more specific, a focus value of the lens mounted on
the rotor (130) is measured by the image sensor in the driving
section determined by the posture of the VCM (100) for implementing
the auto focus operation. In a case the focus value is not an
optimum focus value, a current on the VCM (100) is increased or
decreased as much as a predetermined step to move the rotor (130),
and a DOFV (Difference of Focus Value), which is a difference value
between a current focus value and a previous focus value is
calculated to determine a focus adjustment state.
[0098] As a result of the determination, if the focus value is an
optimum focus value, the rotor (130) is fixed to a current
position, and the image sensor is used to convert an outside light
to an image or a video.
[0099] Although the exemplary embodiment of the present disclosure
has illustrated and explained that the posture of the VCM is
determined by gyro sensor, the non-driving section of the rotor is
skipped, and an auto focusing function is implemented using one
auto focus algorithm performing the auto focusing operation from
the driving section of the rotor, alternatively, the auto focusing
function may be implemented using a plurality of auto focus
algorithms in response to the posture of the VCM.
Third Exemplary Embodiment
[0100] FIG. 14 is a flowchart illustrating an auto focusing method
of a camera module according to a third exemplary embodiment of the
present disclosure.
[0101] To be more specific, referring to FIGS. 1 and 14, in order
to implement the auto focusing operation, in a case a driving
current is not applied from the camera module, a posture of the
rotor (130) contacted to the base (100) by the elastic member
(140), which is a reference plane, is first determined by using a
position detection sensor such as a gyro sensor (S40).
[0102] Successively, an initial driving current is applied to the
rotor (130) in order to implement the auto focusing operation to
cause the rotor (130) to be arranged an upper surface of the base
(110) (S45).
[0103] Thereafter, one auto focus algorithm is selected from a
plurality of auto focus algorithms formed in number corresponding
to that of the postures of the rotor (130) of the VCM (100) (S50).
The auto focus algorithm may include a first auto focus algorithm
corresponding to the `down` posture, a second auto focus algorithm
corresponding to the `side` posture, and a third auto focus
algorithm corresponding to the `up` posture.
[0104] An auto focusing operation of non-driving section of the
rotor (130) despite the application of the driving current is
skipped by the auto focus algorithm selected from the plurality of
auto focus algorithms in response to the posture of the VCM (100),
and the auto focusing operation is performed from the driving
section of the rotor (130) driven by the driving current, and an
auto focusing operation is performed within a shortened period of
time over the auto focusing operation of the non-driving section
(S60).
[0105] As apparent from the foregoing, the auto focusing operation
of non-driving section of the rotor (130) despite the application
of the driving current is skipped, and the auto focusing operation
is performed only from the driving section of the rotor driven by
the driving current, whereby auto focusing time can be effectively
shortened and a current consumption at the non-driving section is
reduced to reduce the power consumption.
[0106] The above-mentioned camera module and the auto focusing
method of the camera module according to the present disclosure
may, however, be embodied in many different forms and should not be
construed as limited to the embodiment set forth herein. Thus, it
is intended that embodiment of the present disclosure may cover the
modifications and variations of this disclosure provided they come
within the scope of the appended claims and their equivalents.
While particular features or aspects may have been disclosed with
respect to several embodiments, such features or aspects may be
selectively combined with one or more other features and/or aspects
of other embodiments as may be desired.
* * * * *