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Digital Camera Patent Abstract
A digital camera module (100) includes a barrel (1), an IR-cut filter
(3) and at least one lens element (4). The IR-cut filter is fixed
to the barrel. The at least one lens element is received in the
barrel and is disposed behind the IR-cut filter so that incoming
light firstly passes through the IR-cut filter, then passes through
the at least lens element. The IR-cut filter may protect the at
least one lens element so as to improve the quality of the digital
camera.
Digital Camera Patent Claims
1. A digital camera lens module comprising: a barrel, an IR-cut
filter fixed to the barrel; at least one lens element received in
the barrel, and the at least one lens element being disposed behind
the IR-cut filter so that incoming light firstly passes through
the IR-filter, then passes through the at least lens element.
2. The digital camera lens as claimed in claim 1, wherein a fringe
of the IR-cut filter is blackened.
3. The digital camera lens as claimed in claim 1, wherein the barrel
includes a flange and a barrel body formed together, and the IR-cut
filter is fixed in the flange.
4. The digital camera lens as claimed in claim 3, wherein the flange
has a rectangular hole defined in one side thereof, a frustum hole
defined in an opposite side thereof, and the rectangular hole communicate
with the frustum hole.
5. The digital camera lens as claimed in claim 4, wherein the IR-cut
filter is received in the rectangular hole, and the outside portions
of IR-cut filter where the extending lines of the frustum hole intersect
with the rectangular hole are blackened.
6. The digital camera lens as claimed in claim 3, wherein the barrel
body has a through hole defined therein, and the through hole communicates
with the rectangular hole and the frustum hole.
7. The digital camera lens as claimed in claim 1, wherein the at
least one lens element includes a first lens element and a second
lens element, the first lens element being immediately behind the
IR-cut filter along an optical path, and the first lens element
is a plastic lens.
8. The digital camera lens as claimed in claim 7, wherein the second
lens is a plastic lens.
9. The digital camera lens as claimed in claim 7, wherein a field
stop is disposed between the first lens element and the second lens
element.
10. A digital camera module having an optical path, the digital
camera module comprising: a barrel having an optical opening allowing
light to transmit therethrough; an IR-cut filter attached to the
barrel at the optical opening, the IR-cut filter being within the
optical path; at least one lens element received in the barrel and
being within the optical path, the at least one lens element disposed
behind the IR-cut filter with respect to the optical path; a base
engaging with the barrel; and an image sensor fixed in the base,
relative to the optical path.
11. The digital camera module as claimed in claim 10, wherein a
fringe of the IR-cut filter is blackened.
12. The digital camera module as claimed in claim 10, wherein the
barrel includes a flange and a barrel body formed together, the
IR-cut filter is fixed in the flange.
13. The digital camera module as claimed in claim 12, wherein the
flange has a rectangular hole defined in one side thereof, and a
frustum hole defined in an opposite side thereof, the rectangular
hole communicates with the frustum hole.
14. The digital camera module as claimed in claim 12, the IR-cut
filter is received in the rectangular hole, and the outside portions
of IR-cut filter where the extending lines of the frustum hole intersect
with the rectangular hole are blackened.
15. The digital camera module as claimed in claim 12, the barrel
body has a through hole defined therein, and the through hole communicates
with the rectangular hole and the frustum hole.
16. The digital camera module as claimed in claim 10, wherein the
at least one lens element includes a first lens element and a second
lens element, and the first lens element and the second element
are aspheric plastic lenses.
17. The digital camera module as claimed in claim 10, wherein the
barrel defines an outer thread at the outer periphery wall, the
base is a hollow cylinder, the inner periphery wall is defined an
inner thread, and the outer thread of the barrel engages in the
inner thread of the base.
18. A digital camera module comprising: a barrel having a front
barrel end and a back barrel end; a filter attached to a front portion
of the front barrel and sealing the front barrel end; a base attached
to the back barrel end and sealing the back barrel end, whereby
a closed space is cooperatively formed between the barrel, the filter,
and the base; an image sensor fixed to the base; and at least one
lens received in the barrel and located between the filter and the
image sensor, the lens being configured for routing incoming light
to the image sensor.
19. The digital camera module of claim 18, wherein the filter is
an IR-filter.
20. The digital camera module of claim 18, wherein the at least
one lens is a plastic lens.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to digital camera,
and more particularly, to a lens module for a digital camera.
[0003] 2. Discussion of the Related Art
[0004] 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.
[0005] However, the color spectrum seen by a CCD or CMOS camera
is much wider than the spectrum seen by the human eye. Especially
in the near infrared region of the spectrum the difference in sensitivity
is significant. Since many light sources, including the sun, emit
infrared light, a CCD or CMOS camera in daylight will therefore
see a significant amount of infrared light resulting in strange
colors. Therefore, many lenses need to be designed with an IR-cut
filter. The IR-cut filter may block the transmission of the infrared
light while passing the visible light.
[0006] A typical lens for a digital camera is represented in FIG.
2. The lens includes an aperture stop 81, a first lens element 82,
a field stop 83, a second lens element 84, an IR-cut filter 85 and
a CMOS image sensor 86. The first lens element 82 and the second
lens element 84 are made of plastic, and are aspheric lens elements.
The light reflected from an image object passes through the first
lens element 82 and the second lens element 84. The light is then
focused and then passes through the IR-cut filter 85. The light
then arrives at the CMOS image sensor 86. The aperture stop 81 can
adjust the quantity of the light entering from the outside. The
field stop 83 can control the quantity of the light entering the
CMOS image sensor 86. The IR-cut filter 85 filters the infrared
rays from the light. Although the lens is light and does not easily
break owing to using plastic lens elements, the first lens element
82 is located at the front, and is easily scraped or abraded which
can effect the image quality.
[0007] Therefore, a digital camera with a new lens module is desired
in order to overcome the above-described shortcomings.
SUMMARY OF THE INVENTION
[0008] In one embodiment thereof, a digital camera lens module
includes a barrel, an IR-cut filter and at least one lens element.
The IR-cut filter is fixed to the barrel. The at least one lens
element is received in the barrel and is disposed behind the IR-cut
filter so that incoming light firstly passes through the IR-cut
filter, then passes through the at least lens element.
[0009] 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
[0010] Many aspects of the lens for digital camera 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 digital camera module. Moreover, in the drawings, like reference
numerals designate corresponding parts throughout the several views.
[0011] FIG. 1 is an cut-away view of an embodiment of a lens for
a digital camera; and
[0012] FIG. 2 is a conventional schematic view of a lens for a
digital camera.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0013] Referring now to the drawing, FIG. 1 shows a digital camera
module 100, according to a preferred embodiment. The digital camera
module 100 is adapted for use in a digital camera or a 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 and digital camcorders as well. The digital
camera module 100 includes a barrel 1, a base 2, an IR-cut filter
3, a first lens element 4, a field stop 5, a second lens element
6 and an image sensor 7.
[0014] The barrel 1 is substantially a cylinder in shape, and has
a barrel body 10 and a flange 11 formed together. The barrel body
10 has a through hole 13 defined therein. The flange 11 is formed
at one end of the barrel body 10. The flange 11 has a rectangular
hole 111 defined in one side thereof, and a frustum hole 112 defined
in an opposite side thereof. The frustum hole 112 communicates with
the rectangular hole 111 and the through hole 13 so that light beams
can be transmitted therethrough. The barrel body 10 has an outer
thread 12 defined in the outside periphery wall thereof.
[0015] The base 2 is substantially a hollow cylinder in shape.
An outer diameter of the barrel body 10 is approximately equal to
an inner diameter of the base 2 so that the barrel 1 may be inserted
into the base 2. The base 2 has an inner thread 21 defined in the
inside periphery wall thereof for engaging with the outer thread
12 of the barrel 1.
[0016] The IR-cut filter 3 is situated in the rectangular hole
111 of the barrel 1. At least one surface of the IR-cut filter 3
is coated with an IR-cut coating. The IR-cut coating can filer out
infrared rays from incoming light so as to improve the image quality.
The outside portions of IR-cut filter where the two extending lines
"B" of the frustum hole intersect with the rectangular
hole are blackened. The blackened portions of the IR-cut filter
may absorb those light radiating thereat, thus avoiding the reflection
of the IR-cut filter 3 effecting the image quality.
[0017] The first lens element 4 includes two aspheric surfaces
41 and 42, with both convex to the flange 11. The first lens element
4 is made of plastics. The second lens element 6 also includes two
aspheric surfaces 61 and 62, with both convex to the direction opposite
to the flange 11. The second lens element 6 is made of plastics.
Both of the lens elements are received in the barrel body 10 of
the barrel 1.
[0018] The field stop 5 is ringlike in shape, and is received in
the barrel body 10 of the barrel 1. The field stop 5 is located
between the first lens element 4 and the second lens element 6.
The field stop 5 may control/limit the quantity of the light arriving
at the image sensor 7, thereby preventing ghost images or lens-flare.
[0019] The image sensor 7 is usually a charge-coupled device (CCD)
or a complementary metal-oxide semiconductor (CMOS). The image sensor
7 has an image sensor surface 71, and the image sensor 7 is located
behind the second lens element 6, and is received in the base 2.
The image sensor 7 may transform light signals to electronic signals.
[0020] In assembly, firstly, the blackened IR-cut filter 3 is fixed
in the rectangular hole 111 of the barrel 1 by means of adhesion
and/or welding. The first lens element 4, the field stop 5 and the
second lens element 6 are received in the barrel body 10 of the
barrel 1 in that order, with the first aspheric surface 41 of the
first lens element 4 being accommodated in the frustum hole 112.
After that, the image sensor 7 is fixed in the base 2 by means of
adhesion and/or welding. Finally, the assembled barrel 1 is threaded
into the base 2. Accordingly, all of the above elements are assembled
together.
[0021] In use, the digital camera module 100 can be fitted within
a portable electronic device, such as a mobile phone, and the image
sensor 7 is electrically connected with a circuit board of the mobile
phone for receiving power. When taking pictures, the light reflected
from an image object (not shown) firstly passes through the IR-cut
filter 3. The IR-cut filter 3 filters the infrared rays from the
incoming light so as to improve the image quality. Then, the light
is transferred to the first lens element 4, then the field stop
5 and then the second lens element 6 in that order. The first lens
element 4 and the second lens element 6 focus the light, after which,
the light arrive at the image sensor 7. The image sensor 7 then
transforms the light signal to an electronic signal, permitting
the storage of the image information in the digital camera memory.
[0022] A main advantage of the digital camera module with a front
IR-cut filter is that the IR-cut filter not only filters infrared
rays from incoming light, but also protects the first lens element.
[0023] In a still further alternative embodiment, the base 2 may
be rectangular. The base 2 and the barrel 1 may be molded together
as a whole during manufacture. In the above embodiment, the IR-cut
filter, the first lens element, the field stop, the second lens
element and the image sensor are disposed on the same optical path.
[0024] As described above, the base may has a bottom for sealing
the barrel. Accordingly, a closed space is cooperatively formed
between the barrel, the filter and the base.
[0025] As described above, the preferred embodiment provides a
digital camera module with a front IR-cut filter for devices such
as mobile phones, having both simplicity and ease of use. It is,
however, to be understood that the digital camera module could potentially
be useful in other applications in which it may be desirable to
allow incoming light to be adjusted so as to attain a clear image.
[0026] It is believed that the present embodiments and their advantages
will be understood from the foregoing description, and it will be
apparent that various changes may be made thereto without departing
from the spirit and scope of the invention or sacrificing all of
its material advantages, the examples hereinbefore described merely
being preferred or exemplary embodiments of the invention. |