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Digital Camera Patent Abstract
A digital camera module (100) with an auto-focusing function is
adapted for use in a foldable electronic device. The digital camera
module includes a lens mount (10), a lens barrel (20), a voice coil
actuator (40), and an image pick-up module (50). The lens barrel
receives at least one lens (24) therein and is mounted on/in the
lens mount. The lens barrel is made of a composite material including
a magnetic metallic nano-powder. The voice coil actuator is adapted
for cooperating with the lens barrel to form a magnetic loop. The
image pick-up module is disposed under the lens mount and is configured
for receiving an image from the at least one lens and converting
that image to an electrical signal.
Digital Camera Patent Claims
1. A digital camera module with an auto-focusing function, comprising:
a lens mount; a lens barrel having at least one lens positioned
therein, the lens barrel being mounted at least one of on and in
the lens mount, the lens barrel being made of a composite material
having a magnetic metallic nano-powder therein; a voice coil actuator
adapted for cooperating with the lens barrel to form a magnetic
loop; and an image pick-up module disposed under the lens mount,
the image pick-up module being configured for receiving from the
at least one lens light corresponding to an image.
2. The digital camera module as claimed in claim 1, wherein the
magnetic metallic nano-powder is selected a group consisting of
manganese-zinc-ferrite, nano cobalt particles, and nano nickel particles,
or a combination thereof.
3. The digital camera module as claimed in claim 1, wherein the
composite material used for the lens barrel is made of a plastic
mixed with the magnetic metallic nano-powder.
4. The digital camera module as claimed in claim 3, wherein the
magnetic metallic nano-powder in the lens barrel has a weight percent
less than about one percent.
5. The digital camera module as claimed in claim 4, wherein the
magnetic metallic nano-powder is essentially equally distributed
throughout the plastic of the lens barrel.
6. The digital camera module as claimed in claim 1, wherein the
lens barrel is manufactured by an injection molding process.
7. The digital camera module as claimed in claim 1, further comprising
a sleeve, the voice coil actuator being located outside of the sleeve.
8. The digital camera module as claimed in claim 1, wherein the
lens mount comprises a plate and a cylindrical lens holder disposed
on the plate.
9. The digital camera module as claimed in claim 8, wherein an
inner diameter of the sleeve is slightly larger than an outer diameter
of the lens holder such that the sleeve can be placed around the
lens holder.
10. The digital camera module as claimed in claim 1, wherein the
lens holder has internal thread defined in peripheral wall thereof.
11. The digital camera module as claimed in claim 10, wherein the
lens barrel has external thread defined in outer peripheral wall
thereof, the external thread thereof being configured for movably
engaging with the internal thread of the lens holder.
12. The digital camera module as claimed in claim 1, wherein the
image pick-up module includes an image pick-up sensor, a printed
circuit board, and a flexible circuit board.
13. The digital camera module as claimed in claim 12, wherein the
image pick-up sensor is electrically connected with the printed
circuit board, and the printed circuit board is electrically connected
with the flexible circuit board.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to a digital camera
module with an auto-focusing function and, more particularly, to
a small-sized digital camera module with an auto-focusing function
and to a portable electronic device, such as a mobile phone or a
Personal Digital Assistant (PDA), having such a camera module mounted
therein.
[0003] 2. Discussion of the Related Art
[0004] Recently, with the development of wireless communication
technologies, there are many cases where digital cameras are mounted
in mobile phones or PDAs.
[0005] Generally, digital cameras are image recording media capable
of photographing a plurality of still images without using film.
Such a digital camera typically uses an image pickup device, which
is a kind of semiconductor device, such as a Charge Coupled Device
(CCD) or Complementary Metal Oxide Semiconductor (CMOS). In the
digital camera, an object image formed on the image pickup device
through a lens is converted into an electrical signal by the image
pickup device, and the electrical signal is stored as a digital
signal, e.g., in the camera unit or in a mobile phone or PDA in
which the digital camera is mounted.
[0006] Since the digital camera is desirably mounted in small mobile
phones or PDAs, a fixed focus lens module is usually used to facilitate
mounting thereof within a small phone or PDA. However, images photographed
by a digital camera module with a fixed focus lens module tend to
be poor in quality. It is partly due to the fixed focus lens, which
is incapable of adjusting focal length to make a clearer image.
[0007] A kind of conventional digital camera with a focusing function
usually uses an actuator, such as step motor, to drive the lens
module, such as disclosed in Taiwan Patent No. 88200669. Referring
to FIG. 3 (Prior Art), a focusing adjusting apparatus includes an
inner housing 60, a lens 62, a circular gear 64, and a step motor
66. The lens 62 and the step motor 66 are received in the inner
housing 60. One end of the step motor 66 is connected with a driving
gear 662. The driving gear 662 drives the circular gear 64 to rotate,
which makes the lens 62 located in the circular gear 64 move. However,
the focusing adjusting apparatus using such a step motor is relatively
large in volume and consumes a substantial amount of power, especially
relative to the amount of power that can be stored in the typical
battery system of a mobile phone or PDA. As such, a step motor is
not suitable to be used in mobile phone or PDA, which needs to be
small and power saving.
[0008] Another kind of conventional digital camera with a focusing
function usually uses an actuator such as coil motor to drive the
camera lens disclosed in U.S. Patent Application No. 2004016587,
published Aug. 26, 2004. Referring to FIG. 4 (Prior Art), a drive
source of a camera lens is disclosed. The camera lens includes a
camera lens mount 70, a telescopic lens 72, a coil stator 74, and
a magnetic ring rotor 76. The coil stator 74 and the magnetic ring
rotor 76 cooperate with each other to drive the telescopic lens
72. The inside of the camera lens mount 70 is built with the coil
stator 74 to place the magnetic ring rotor 76 inside a designated
space 742. The outside of the telescopic lens 72 is designed with
an external thread member 722 to allow it to be screwed on an internal
thread 764 on the inside of a spindle 762 of the magnetic ring rotor
76. The magnetic ring rotor 76 rotates under the reaction induced
by the coil stator 74, and the internal thread 764 of the spindle
762 drives the external thread 722 of the telescopic lens 72 for
telescopic motion. However, the presence of the magnetic rotor 76
increases the weight of the digital camera lens. Further, the combination
of the coil stator 74, the magnetic ring rotor 76, the external
thread member 722, and the telescopic lens 72, together, will occupy
a relatively large volume, and the adjustment of such a combination
will consume a substantial amount of power, especially relative
to the amount of power that can be stored in the typical battery
system of a mobile phone or PDA.
[0009] What is needed, therefore, is a digital camera module with
an auto-focusing function, which satisfies the needs for performance
enhancement, downsizing, and power saving.
SUMMARY OF THE INVENTION
[0010] A digital camera module with auto-focusing function is adapted
for use in a foldable electronic device. The digital camera module
includes a lens mount, a lens barrel, a voice coil actuator, and
an image pick-up module. The lens barrel receives at least one lens
therein and is mounted on/in the lens mount. The lens barrel is
made of a material having a magnetic metallic nano-powder mixed
therein. The voice coil actuator is adapted for cooperating with
the lens barrel to form a magnetic loop. The image pick-up module
is disposed under the lens mount and is configured for generating
a signal based upon an image picked up from the at least one lens.
[0011] A main advantage of the digital camera module with auto-focusing
function is that a magnetic field loop is produced between the voice
coil actuator and the lens barrel to drive the telescopic movement
of the lens barrel. There are no any additional element between
the voice coil actuator and the lens barrel, such as magnet or stepper
motor. The digital camera module with auto-focusing function has
simply structure.
[0012] Other advantages and novel features will become more apparent
from the following detailed description when taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Many aspects of the digital camera module with an auto-focusing
function can be better understood with reference to the following
drawings. The components in the drawings are not necessarily to
scale, the emphasis instead being placed upon clearly illustrating
the principles of the present digital camera module with an auto-focusing
function. Moreover, in the drawings, like reference numerals designate
corresponding parts throughout the several views.
[0014] FIG. 1 is an exploded, isometric view of a digital camera
module with an auto-focusing function, in accordance with one preferred
embodiment;
[0015] FIG. 2 is an cross-sectional, assembled view of the digital
camera module of FIG. 1;
[0016] FIG. 3 is an isometric view of a conventional digital camera
module with an auto-focusing function; and
[0017] FIG. 4 is an isometric view of another conventional digital
camera module with an auto-focusing function.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0018] Referring now to the drawings, FIG. 1 shows a digital camera
module 100 with an auto-focusing function, according to a preferred
embodiment. The digital camera module 100 is adapted for use in
portable electronic device such as a mobile phone or a Personal
Digital Assistant (PDA), but the compact nature thereof could prove
useful in compact digital camera units or digital camcorders, as
well. The digital camera module 100 includes a lens mount 10, a
lens barrel 20, a sleeve 30, a voice coil actuator 40, and an image
pick-up module 50. The lens mount 10 is mounted on and/or above
the image pick-up module 50. The sleeve 30 receives the lens barrel
20 mounted on and/or in the lens mount 10. The voice coil actuator
40 is wound around an outside of the sleeve 30.
[0019] The lens mount 10 includes a L-shaped plate 12 and a round
lens holder 14 located on the L-shaped plate 12. The L-shaped plate
12 defines a rectangular groove 122 in the bottom thereof. The lens
holder 14 is a hollow cylinder with two open ends so that light
beams can be transmitted therethrough. The lens holder 14 defines
a receiving cavity (not labeled) inside. The inner periphery of
the lens holder 14 is designed with an internal thread 142.
[0020] The lens barrel 20 is a hollow cylinder with an open end
(not labeled) and a half-closed (i.e., partially-closed) end 22
and receives a plurality of lenses 24 (referring to FIG. 2) therein.
The lens barrel 20 defines a hole 222 in the center of the half-closed
end 22 so that light beams can be transmitted therethrough. The
lens barrel 20 has an external thread 26 on the outside thereof
adjacent the open end. The external thread 26 of the lens barrel
20 corresponds to the internal thread 142 of the lens mount 10.
The lens barrel 20 is placed in and engages with the lens holder
14 of the lens mount 10. The lens barrel 20 is axially located in
the receiving cavity of the holder 14. The lens barrel 20 is capable
of moving axially under the influence of the voice coil actuator
40 due to the presence of the screw engagement between the lens
barrel 20 and the lens holder 14 of the lens mount 10.
[0021] The lens barrel 20 is beneficially made of a plastic mixed
with a metallic nano-powder (i.e., a plastic/nano-powder composite).
The metal nano-powder is magnetic (i.e., capable of being attracted
by an appropriately polarized magnet and/or being permanently magnetized)
in nature. The magnetic metal nano-powder can be selected a group
consisting of manganese-zinc-ferrite, nano cobalt particles, and
nano nickel particles, or a combination thereof. Nanoparticles of
other materials (e.g., iron; alloys containing a sufficient amount
of cobalt, nickel, and/or iron) capable of displaying magnetic behavior
would also be considered appropriate. The metal nano-powder is nano-scale
in the approximate range of 1-100 nanometers. The metal nano-powder
is beneficially essentially equally distributed throughout the lens
barrel 20. Due to this even distribution, the action of the voice
coil actuator 40 upon the lens barrel 20 can be expected to be essentially
uniform, contributing to a highly controllable focusing operation.
[0022] The weight percent of the metal nano-powder in the composite
used for lens barrel 20 is dependent on the electromagnetic capability
of the voice coil actuator 40 and on the magnetic properties displayed
by the metal nano-powder. The weight percent of the metal nano-powder
in the lens barrel 20, in most instances, is generally less than
about one percent of the plastic matrix material (i.e., .about.99
wt %, or more, plastic). Since the composite used for the lens barrel
20 is made of such a high proportion of plastic, the weight of the
lens barrel 20 is effectively minimized. In manufacturing, it is
required that the metal nano-powder is mixed in the plastic to form
the composite material. The lens barrel 20 is advantageously manufactured
by first forming the plastic composite and then injecting the plastic
composite into an appropriate mold, thereby achieving the desired
shape.
[0023] The sleeve 30 is a hollow cylinder with an open end (not
labeled) and a half-closed (i.e., partially-closed) end 32. The
sleeve 30 defines a hole 322 in the center of the half-closed end
32 so that light beams can be transmitted therethrough. An inner
diameter of the sleeve 30 is slightly larger than an outer diameter
of the lens holder 14 of the lens mount 10. The sleeve 30 is located
around the lens holder 14 of the lens mount 10 via the open end
thereof and receives the lens barrel 20 therein. The voice coil
actuator 40 is formed, e.g., by winding one or more conductive metal
wires around the sleeve 30. Alternatively, the voice coil actuator
40 could be a separate component, including one or more conductive
windings as a part thereof, capable of being positioned around the
sleeve 30.
[0024] The image pick-up module 50 includes a image pick-up sensor
52, a printed circuit board 54, and a flexible circuit board 56.
The image pick-up sensor 52 can, for example, be a Complementary
Metal-Oxide Semiconductor (CMOS) type sensor or a Charge Coupled
Device (CCD). The image pick-up sensor 52 is electrically connected
with the printed circuit board 54, and the printed circuit board
54 is electrically connected with the flexible circuit board 56.
The image pick-up sensor 52 is disposed on the center of the printed
circuit board 54. The image pick-up sensor 52 aligns with the open
end of the lens holder 14 of the lens mount 10 such that the lens
holder 14 of the lens mount 10 is capable of routing the input light
beams, corresponding to an image being photographed, to the image
sensor 52. A right end of the printed circuit board 54 is connected
with the flexible circuit board 56 so that an image signal can be
output to a signal processing unit (not labeled).
[0025] Referring now to FIG. 2, in assembling the digital camera
module 100, the lens mount 10 is fixed on the print circuit board
54 of the image pick-up module 50 by glue or another adhesive, with
the image pick-up sensor 52 aligning with the open end of the lens
holder 14 to receive a light signal thereupon. The printed circuit
board 54 is received in the rectangular groove 122 of the L-shaped
plate 12 of the lens mount 10. Then, the lens barrel 20 is rotated
into and mounted on the lens holder 14 of the lens mount 10, with
the external thread 26 of the lens barrel 20 engaging with the internal
thread 142 of the lens holder 14. The voice coil actuator 40 is
wound around the outside of the sleeve 30, and the sleeve 30 is
located around the lens holder 14 and the lens barrel 20.
[0026] In use, the digital camera module 100 is equipped within
a portable electronic device, such as mobile phone, and the voice
coil actuator 40 is electrically connected with a circuit board
of the mobile phone for capturing electrical power. Because the
lens barrel 20 is made of a plastic filled with a magnetic nano-powder,
the lens barrel 20 is also magnetic and can thus be influenced by
an electromagnetic field. When the voice coil actuator 22 is induced
with a current flow, the coil 22 generates a magnetic field, which
may be same as or contrary to the magnetism of the lens barrel 20.
Thus, a magnetic force that may be a magnetic attractive force or
a magnetic repulsive force is generated between the lens barrel
20 and the lens holder 14. The magnetic force can make the lens
barrel 20 rotate. During the rotation course of the lens barrel
20 relative to the lens holder 14, the lens barrel 20 moves axially
relative to the lens holder 14 under the thread engagement between
the external thread 26 of the lens barrel 20 and the internal thread
142 of the lens holder 14, thereby resulting in the stable telescopic
movement of the lens barrel 20. Thus, the focusing purpose is achieved
by changing the distance between the image pick-up sensor 52 and
the lenses 24 in the lens barrel 20.
[0027] A main advantage of the digital camera module 100 with an
auto-focusing function is that a magnetic field loop is produced
directly between the voice coil actuator 40 and the lens barrel
20 to drive the telescopic movement of the lens barrel 20. There
are no additional elements between the voice coil actuator 40 and
the lens barrel 20, such as a magnet or a stepper motor. The digital
camera module 100 thus has a simple, compact structure.
[0028] It is to be understood, however, that even though numerous
characteristics and advantages of the present embodiments have been
set forth in the foregoing description, together with details of
the structures and functions of the embodiments, the disclosure
is illustrative only, and changes may be made in detail, especially
in matters of shape, size, and arrangement of parts within the principles
of the invention to the full extent indicated by the broad general
meaning of the terms in which the appended claims are expressed.
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