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Digital Camera Patent Abstract
A digital camera module (100) includes a lens module (110), an image
sensor (120) and a linear voice coil actuator (130). The lens module
further includes a lens set (111), an infrared cut filter (112),
a spacer set (113) and a barrel (114). The image sensor is a CCD
or a CMOS. The linear voice coil actuator includes an elongated
soft magnetic core (131), a tubular permanent magnet (132) positioned
parallel to the axis of the core, a sliding holder (133) and a coil
(134) attached to the sliding holder and positioned to interact
with the permanent magnet along the axis of the core. The digital
camera module further includes a servo-controller (140) for controlling
the movement of the linear voice coil actuator.
Digital Camera Patent Claims
1. A digital camera module comprising: a lens module configured
for transmitting an image; an image sensor configured for receiving
the image transmitted from the lens module and converting the image
from a light signal form into an electronic signal form; and a linear
voice coil actuator configured for driving the image sensor to move
so as to properly receive the image transmitted from the lens module.
2. The digital camera module as claimed in claim 1, wherein the
lens module further comprises a lens set, an infrared cut filter,
a spacer set and a barrel receiving the lens set and the infrared
cut filter therein.
3. The digital camera module as claimed in claim 2, wherein the
lens set comprises at least a glass aspheric lens and at least a
plastic aspheric lens.
4. The digital camera module as claimed in claim 3, wherein the
aspheric lens has an anti-reflective film formed on at least one
surface thereof
5. The digital camera module as claimed in claim 1, wherein the
image sensor is a CCD.
6. The digital camera module as claimed in claim 1, wherein the
image sensor is a CMOS.
7. The digital camera module as claimed in claim 1, wherein the
linear voice coil actuator comprises: an elongated soft magnetic
core; a tubular permanent magnet receiving the elongated soft magnetic
core therein; a coil surrounding and moveable relative to the elongated
soft magnetic core; and a sliding holder having a fixing portion
received in the tubular permanent magnet and fixedly coupled to
the coil, a driving portion configured for driving the image sensor
to move, and a connecting portion interconnecting the fixing portion
with the driving portion.
8. The digital camera module as claimed in claim 7, wherein the
tubular permanent magnet has a slit configured for allowing the
connecting portion to extend therethrough and to be slidable therein.
9. The digital camera module as claimed in claim 7, wherein the
digital camera module further includes a servo-controller for controlling
movement of the coil of the linear voice coil actuator.
10. The digital camera module as claimed in claim 7, wherein the
image sensor is attached to the driving portion of the sliding holder
of the linear voice coil actuator and is arranged in the tubular
permanent magnet.
11. The digital camera module as claimed in claim 7, wherein the
image sensor is attached to the driving portion of the sliding holder
of the linear voice coil actuator and is arranged outside the tubular
permanent magnet.
12. The digital camera module as claimed in claim 1, wherein a
step resolution of the linear voice coil actuator is in a range
of 0.01 micrometers to 0.02 micrometers.
Digital Camera Patent Description
TECHNICAL FIELD
[0001] The invention relates generally to digital camera modules,
and more particularly, to an image pickup module for digital camera
having auto-focus and zoom mechanism.
DISCUSSION OF RELATED ART
[0002] The use of digital cameras has increased greatly over the
past few years. With the development of wireless communication technologies
many mobile phones or Personal Digital Assistants (PDAs) now mount
digital cameras. Generally, digital cameras are image recording
media capable of photographing a plurality of still images without
using films. Such a digital camera uses an image pickup device,
which is a kind of semiconductor device, such as a charged 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 in a mobile phone or PDA in which the digital camera
is mounted.
[0003] Most automatic cameras include a device for automatically
focusing a subject to be photographed. An auto-focus device does
not require the user to manually bring the subject into focus, thereby
reducing focusing errors and making modern automatic cameras more
easy to use. A typical auto-focus device is controlled by a microcontroller
to control the relative position of a pair of lenses. The microcontroller
also coordinates other devices to perform an active range finding
function (e.g. infrared) or a passive range finding function. Once
the range of the subject from the camera is determined the microcontroller
controls the auto-focus device to position the lenses to correctly
focus the subject.
[0004] Since the digital camera for image pickup devices are intended
for mounting in small mobile phones or PDAs, technologies for miniaturization
of digital camera components are key to a successful product. Cost
effective automatic cameras usually employ a two-position lens system
where the lens system can be set to either a far-focus or a near-focus
position. A simplified range finding system provides ranging information
to a microcontroller that controls the two positional lens system.
Focus is then automatically established based on the subject being
at infinity or at a normal subject distance of about 8-12 feet (2.4-3.6
meters).
[0005] The digital camera industry, like other technological industries,
is constantly striving to reduce the size of products, while maintaining
or increasing the product's functionality. Conventional image pickup
modules for digital cameras do not use space economically and have
overly complicated linkage mechanisms and other unnecessary components.
[0006] What is needed, therefore, is a digital camera module having
an auto-focus and zoom mechanism, and which could function to reduce
size, weight, and costs of modern automatic cameras.
SUMMARY
[0007] The present invention provides a digital camera module having
an auto-focus and zoom mechanism. In one embodiment, the digital
camera module includes a lens module, an image sensor and a linear
voice coil actuator. The lens module is configured for transmitting
images. The lens module further includes a lens set, an infrared
cut filter, a spacer set and a barrel receiving the lens set and
the infrared cut filter therein. The lens set includes at least
a glass aspherical lens and at least a plastic aspherical lens.
The image sensor is a charged coupled device (CCD) or a complementary
metal oxide semiconductor (CMOS).
[0008] The linear voice coil actuator includes an elongated soft
magnetic core, a tubular permanent magnet, a coil and a sliding
holder. The tubular permanent magnet receives the elongated soft
magnetic core therein. The coil surrounds and is moveable relative
to the elongated soft magnetic core. The sliding holder has a fixing
portion, a driving portion and a connecting portion. The fixing
portion is received in the tubular permanent magnet and coupled
to the coil. The driving portion is configured for driving the image
sensor to move. The connecting portion interconnects the fixing
portion and the driving portion. The digital camera module further
includes a servo-controller for controlling the action of the linear
actuator.
[0009] Advantages and novel features of the present digital camera
module will become more apparent from the following detailed description
of preferred embodiments when taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Many aspects of the present digital camera module can be
better understood with reference to the following drawings. The
components in the drawings are not necessarily drawn to scale, the
emphasis instead being placed upon clearly illustrating the principles
of the present invention.
[0011] FIG. 1 is a schematic, isometric view of a digital camera
module in accordance with a first preferred embodiment;
[0012] FIG. 2 is a schematic, cross-sectional view of a lens module
of the digital camera module of FIG. 1, taken along line II-II;
[0013] FIG. 3 is a schematic, horizontal cross-sectional view of
a linear voice coil actuator of the digital module of FIG. 1, taken
along line III-III;
[0014] FIG. 4 is a schematic, vertical cross-sectional view of
a linear voice coil actuator of the digital module of FIG. 1, taken
along line IV-IV;
[0015] FIG. 5 is a schematic, isometric view of a digital camera
module in accordance with a second preferred embodiment;
[0016] FIG. 6 is a schematic, horizontal cross-sectional view of
a linear voice coil actuator of the digital module of FIG. 5, taken
along line V-V; and
[0017] FIG. 7 is a schematic, vertical cross-sectional view of
a linear voice coil actuator of the digital module of FIG. 6, taken
along line VI-VI.
[0018] Corresponding reference characters indicate corresponding
parts throughout the several views. The exemplifications set out
herein illustrate at least one preferred embodiment of the present
digital camera module, in one form, and such exemplifications are
not to be construed as limiting the scope of the invention in any
manner.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0019] Reference will now be made to the drawings to describe embodiments
of the present digital camera module in detail.
[0020] Referring to FIG. 1, a digital camera module 100 according
to a first preferred embodiment is shown. The digital camera module
100 includes a lens module 110, an image sensor 120 and a linear
voice coil actuator 130. The lens module 110 is configured for transmitting
an image from outside the digital camera module 100. The image sensor
120 is configured for receiving the image transmitted from the lens
module and converting the image from a light signal form into an
electronic signal form. The image sensor 120 is connected to the
linear voice coil actuator 130. The linear actuator 130 is adapted
to drive the image sensor 120 nearer to or further away from the
lens module 110 for realization of auto-focus and zoom function.
The linear voice coil linear voice coil actuator 130 is controlled
by a servo-controller 140.
[0021] Referring to FIG. 2, the lens module 110 includes a lens
set 1 11, an infrared cut filter 112, a spacer set 113 and a barrel
114. The lens set 111 includes a group of aspheric lenses. The aspheric
lens is selected from a group consisting of a glass aspheric lens
(G) and a plastic aspheric lens (P). The hybrid combination of the
lens set 111 can be 1G2P, 3P, 2G1P, 3G or more lenses. Resolution
of the lens set 111 can be 1.3 mega pixels, 2 mega pixels, 3 mega
pixels, 4 mega pixels, 5 mega pixels, 6 mega pixels or more. Resolution
of more than 3 mega pixels requires four aspheric lenses. All surfaces
of the lens set 111 have an anti-reflective coating. A spacer set
113 is placed between each lens of the lens set 111 and its neighboring
lenses. The infrared cut filter 112 is placed between the lens set
111 and the image sensor 112. The lens set 111, the spacer set 113
and the infrared cut filter 112 are accommodated and fixed in the
barrel 114.
[0022] An image is shone from the outer of the digital camera module
100 into the lens module 110, and received by the image sensor 120
for converting the image into electrical signals. A 1/4 inch complementary
metal oxide semiconductor (CMOS) sensor is used as the image sensor
120. The lens module 110 is designed to be suitable for a device
equipped with a 1/4 inch CMOS sensor. Alternatively, the image sensor
120 can be a charged coupled device (CCD).
[0023] Referring to FIGS. 3 and 4, the linear voice coil actuator
130 includes an elongated soft magnetic core 131 having a longitudinal
axis; a tubular permanent magnet 132 positioned parallel to the
longitudinal axis of the core 131; a sliding holder 133 placed between
the core 131 and the permanent magnet 132; and a coil 134 attached
to the sliding holder 133 and positioned to interact with the tubular
permanent magnet 132 along the axis of the core 131. The tubular
permanent magnet 132 receives the elongated soft magnetic core 131
therein. The coil 134 is surrounded and moveable relative to the
elongated soft magnetic core 131. The sliding holder 133 has a fixing
portion 331, a driving portion 333 and a connecting portion 332.
The fixing portion 331 is received in the tubular permanent magnet
132 and coupled to the coil 134. The driving portion 333 is configured
for driving the image sensor 120 to move. The connecting portion
332 interconnects the fixing portion 331 with the driving portion
333. The tubular permanent magnet 132 is positioned with respect
to the core 131 in a manner so as to define a cavity 135 between
the core 131 and the permanent magnet 132. The sliding holder 133
is positioned in the cavity 135 and moved along the axis of the
core 131 by a magneto-motive force.
[0024] The tubular permanent magnet 132 has a slit 136 configured
for allowing the connecting portion 332 to extend therethrough and
to be slidable therein. The image sensor 120 is attached to the
driving portion 333 of the sliding holder 133 and is arranged outside
the tubular permanent magnet 132. Referring to FIG. 1, the servo-controller
140 for controlling the voice coil actuator 130 includes a sensor
(not shown) connected with the image sensor 120 for monitoring a
linear position of the image sensor 120. By controlling the magneto-motive
force (MMF) in the moving coil 134, a camera user is able to control
the characteristics of the linear voice coil actuator 130, for example
constant force across the stroke, or other desired performance characteristics.
The step resolution of the linear voice coil actuator 130 may be
thereby configured in a range of 0.01 micrometers to 0.02 micrometers.
[0025] Referring to FIGS. 5 to 7, a digital camera module 200 according
to a second preferred embodiment is shown. The digital camera module
200 includes a lens module 210, an image sensor 220 and a linear
voice coil actuator 230. The lens module 210 is the same as the
above described lens module 110. The image sensor 220 is configured
for receiving the image transmitted from the lens module and converting
the image from a light signal form into an electronic signal form.
The image sensor 220 is placed in the linear voice coil actuator
230. A 1/4 inch CMOS sensor generally used in mobile phones is used
as the image sensor 220. The lens module 210 is designed to be suitable
for the specification of a device equipped with the 1/4 inch CMOS
sensor. The image sensor 220 also can be a CCD.
[0026] The linear voice coil actuator 230 can drive the image sensor
220 closer to or further away from the lens module 210 thus enabling
auto-focus and zoom functions. The linear voice coil actuator 230
is controlled by a servo-controller 240. Referring to FIG. 6 and
FIG. 7, the linear voice coil actuator 230 includes an elongated
soft magnetic core set 231 having an axis; a tubular permanent magnet
232 positioned parallel to the axis of the elongated soft magnetic
core set 231; a sliding holder 233; and a coil 234 attached to the
sliding holder 233 and positioned to interact with the tubular permanent
magnet 232 along the axis of the core 231.
[0027] The coil set 231 is an assembly of four separating plates.
The permanent magnet 232 is positioned with respect to the core
set 231. The sliding holder 233 is positioned in the middle of the
permanent magnet 232 and can be moved along the axis of the core
set 231 by a magneto-motive force.
[0028] The image sensor 220 is attached to the sliding holder 233
and is arranged outside the tubular permanent magnet 232. Referring
to FIG. 7, the servo-controller 240 for controlling the voice coil
actuator 230 includes a sensor (not shown) that is connected with
the image sensor 220 to monitor a linear position of the image sensor
220. By controlling the magneto-motive force (MMF) in the moving
coil 234, a camera user is able to control the characteristics of
the linear voice coil actuator 230, for example constant force across
the stroke, or other desired performance characteristic. The step
resolution of the linear voice coil actuator 230 is in a range of
0.01 micrometers to 0.02 micrometers.
[0029] The linear voice coil actuators in accordance with the present
invention can have a variety of shapes, including a rectangular
configuration and a cylindrical configuration. The rectangular embodiments
are described in the above-described sections, as an example, it
being understood that other shapes are contemplated within the spirit
of the present invention. As will be apparent to those skilled in
the art, although not shown in the figures, brackets or other linkages
can be used to connect the image sensors to the load of the linear
voice actuators.
[0030] Finally, it is to be understood that the above-described
embodiments are intended to illustrate rather than limit the invention.
Variations may be made to the embodiments without departing from
the spirit of the invention as claimed. The above-described embodiments
illustrate the scope of the invention but do not restrict the scope
of the invention. |