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Digital Camera Patent Abstract
A lens module (20) is adapted for use in a digital camera. A lens
module includes a lens barrel (21), a plurality of lenses including
a first lens (22) and a second lens (23) and an aligning mechanism.
The two lenses received in the lens barrel. The aligning mechanism
an aligning mechanism configured to align respective optical axes
of the first and second lenses with each othe. The aligning mechanism
is disposed between the two lenses.
Digital Camera Patent Claims
1. A lens module comprising: a lens barrel; a plurality of lenses
including a first lens and a second lens, each lens being received
in the lens barrel; and an aligning mechanism configured to align
respective optical axes of the first and second lenses with each
other, the aligning mechanism disposed between the two lenses.
2. The lens module as claimed in claim 1, wherein the first lens
has a first lens surface facing a second lens surface of the second
lens, the first lens surface and the second lens surface having
formed therein, respectively, a first annular groove and a second
annular groove, the aligning mechanism includes the first annular
groove, the second annular groove, and an orientation means, the
orientation means being disposed between the two lenses and engaging
in the annular grooves.
3. The lens module as claimed in claim 2, wherein the orientation
means comprises a spacer.
4. The lens module as claimed in claim 3, wherein the spacer separates
from the lens barrel.
5. The lens module as claimed in claim 3, wherein the spacer is
annular shaped, an outer diameter of the spacer is equal to or slightly
greater than an outer diameter of corresponding annular grooves,
and an inner diameter of the spacer is equal to or slightly smaller
than an inner diameter of a corresponding annular groove.
6. The lens module as claimed in claim 1, wherein the first lens
has a first lens surface facing a second lens surface of the second
lens, the first lens surface and the second lens surface having
formed thereon, respectively, a first annular protrusion and a second
annular protrusion, the aligning mechanism includes the first annular
protrusion, the second annular protrusion, and an orientation means,
the orientation means is disposed between the two lenses and engaging
with the first and second annular protrusions.
7. The lens module as claimed in claim 6, wherein the orientation
means is a spacer, the spacer has two annular grooves respectively
defined in two surfaces thereof, corresponding to the annular protrusions.
8. The lens module as claimed in claim 7, wherein the spacer separates
from the lens barrel.
9. The lens module as claimed in claim 1, wherein the lens barrel
has an open end and a half-closed end.
10. A lens module comprising: a lens barrel; a plurality of lenses
received in the lens barrel; and a plurality of aligning mechanisms
configured to align optical axes of the plurality of lenses with
each other, each aligning mechanism disposed between each corresponding
two lenses.
11. The lens module as claimed in claim 10, wherein the first lens
has a first lens surface facing a second lens surface of the second
lens, the first lens surface and the second lens surface having
formed therein, respectively, a first annular groove and a second
annular groove, the aligning mechanism includes the first annular
groove, the second annular groove, and an orientation means, the
orientation means being disposed between the two lenses and engaging
in the annular grooves.
12. The lens module as claimed in claim 11, wherein the orientation
means comprises a spacer.
13. The lens module as claimed in claim 12, wherein the spacer
separates from the lens barrel.
14. A lens module comprising: a lens barrel; a plurality of lenses
including a first lens and a second lens, each lens being received
in the lens barrel; and an aligning mechanism respectively fixed
with the first and second lenses radially and axially such that
the optical axes of the first and second lenses align with each
other.
15. The lens module as claimed in claim 14, wherein the first lens
has a first lens surface facing a second lens surface of the second
lens, the first lens surface and the second lens surface having
formed therein, respectively, a first annular groove and a second
annular groove, the aligning mechanism includes the first annular
groove, the second annular groove, and an orientation means, the
orientation means being disposed between the two lenses and engaging
in the annular grooves.
16. The lens module as claimed in claim 15, wherein the orientation
means comprises a spacer.
17. The lens module as claimed in claim 17, wherein the orientation
means comprises a spacer.
18. The lens module as claimed in claim 14, wherein the first lens
has a first lens surface facing a second lens surface of the second
lens, the first lens surface and the second lens surface having
formed thereon, respectively, a first annular protrusion and a second
annular protrusion, the aligning mechanism includes the first annular
protrusion, the second annular protrusion, and an orientation means,
the orientation means is disposed between the two lenses and engages
with the first and second annular protrusions.
19. The lens module as claimed in claim 18, wherein the orientation
means is a spacer, the spacer has two annular grooves respectively
defined in two surfaces thereof, engagingly receiving the annular
protrusions.
Digital Camera Patent Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to lens modules,
and, more particularly, to a lens module for a digital camera.
DESCRIPTION OF RELATED ART
[0002] Currently, digital camera modules are in widespread use
in a variety of portable electronic devices. Most portable electronic
devices are becoming progressively more miniaturized over time,
and digital camera modules are correspondingly becoming smaller
and smaller. For example, digital camera modules are now widely
available as a feature of a mobile phone. Nevertheless, in spite
of the small size of a contemporary digital camera module, consumers
still demand excellent imaging. The quality of the image provided
is mainly dependent upon the optical elements of the digital camera
module.
[0003] Referring to FIG. 4, a contemporary lens module 10 for a
digital camera generally includes a lens barrel 11, a plurality
of lenses 12, 13, a plurality of spacers 14, 15, and an IR-cut filter
16. The lens barrel 11 is a hollow cylinder for receiving the lenses
12, 13, the spacers 14, 15, and the IR-cut filter 16 therein. The
spacers 14, 15 are annular shaped. In assembly, the lenses 12, 13
and the spacers 14, 15 are arranged in the lens barrel 11 in an
alternating fashion. The lenses 12, 13 are adhered to the inside
of the lens barrel 11. Each spacer has a thickness that defines
a desired distance between the lenses 12, 13. The IR-cut filer 16
is disposed at the bottom of the lens barrel. The optical axes of
the lenses 12, 13 are aligned by means of a round tolerance of the
inner wall of the lens barrel 11 and configuration of the spacers
14, 15.
[0004] However, because different plastics have about a 0.5 percent
to 0.6 percent contraction factor during the injection molding process,
precisely matching the inner diameter of the lens barrel 11 to provide
the greatest effect for optical axes alignment is difficult. Further,
the round tolerance of the lens barrel 11 may not meet a desired
requirement or the axis of the lens barrel 11 may not be able to
be aligned with the optical axis of the lenses 12, 13. Although
spacers 14, 15 are adopted, they do not overcome the above-mentioned
deficiencies. Furthermore, though alignment may be obtained initially
this can be lost over time due to the imprecise assembly. That is,
the optical axes of the plurality of lenses 12, 13 may become misaligned.
[0005] What is needed, therefore, is a lens module for a digital
camera, which satisfies the needs for convenient assembly and accurate,
long lasting alignment of optical axes of lenses.
SUMMARY OF INVENTION
[0006] A lens module is adapted for use in a digital camera. The
lens module includes a lens barrel, two lenses and an aligning mechanism.
The two lenses received in the lens barrel. The aligning mechanism
is adapted to align optical axes of the two lenses, and is disposed
between the two lenses.
[0007] 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 DRAWINGS
[0008] Many aspects of the lens module 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 lens
module. Moreover, in the drawings, like reference numerals designate
corresponding parts throughout the several views.
[0009] FIG. 1 is a schematic view of a lens module for a digital
camera, in accordance with a first preferred embodiment, the lens
module including lenses;
[0010] FIG. 2 is a schematic view of the lenses of FIG. 1;
[0011] FIG. 3 is a schematic view of a lens module for a digital
camera, in accordance with a second preferred embodiment; and
[0012] FIG. 4 is a schematic view of a conventional lens module
for a digital camera.
DETAILED DESCRIPTION
[0013] Referring now to the drawings, FIG. 1 shows a lens module
20 for a digital camera, according to a first preferred embodiment.
The lens module 20 is adapted for use in digital cameras used in
portable electronic devices such as a mobile phones or Personal
Digital Assistants (PDAs), but the compact nature thereof could
prove useful in compact digital camera units or digital camcorders,
as well. The lens module 20 includes a lens barrel 21, a first lens
22, a second lens 23, a spacer 24 functioning as an aligning mechanism,
and an IR-cut filter 25. The first lens 22, the spacer 24, the second
lens 23, and the IR-cut filter 25 are received in the lens barrel
21 in that order.
[0014] The lens barrel 21 is a hollow cylinder with an open end
212 and a half-closed (i.e., partially-closed) end 214. The lens
barrel 21 defines a cone-shaped hole 216 in the center of the half-closed
end 214 so that light beams can be transmitted therethrough.
[0015] The first lens 22 and the second lens 23 are both used to
focus the incident light. The first lens 22 and the second lens
23 are circular. The outer diameters of the first lens 22 and the
second lens 23 correspond to the inner diameter of the lens barrel
21.
[0016] The first lens 22 has an outer peripheral surface 221, a
top mounting surface 223, and a bottom mounting surface 224. The
first lens 22 has a meniscus central portion, which defines two
opposite top and bottom aspheric surfaces (not shown) respectively.
The bottom aspheric surface of the first lens 22 is concave. The
first lens 22 has an annular groove 225 defined in the bottom mounting
surface 224, by a groove peripheral surface 226 and a groove bottom
surface 227.
[0017] The second lens 23 has an outer peripheral surface 231,
a top mounting surface 233 and a bottom mounting surface 234. The
second lens 23 has a central portion, which defines two opposite
top and bottom aspheric surfaces (not shown) respectively. The top
and bottom aspheric surfaces protrude outwardly. The second lens
23 has an annular groove 235 defined in the top mounting surface
233, by a groove peripheral surface 236 and a groove bottom surface
237. The optical axis of the annular groove 225 of the first lens
22 and the annular groove 235 of the second lens 23 are aligned
with the optical axis of the first lens 22 and the second lens 23.
An outer diameter of the annular groove 225 of the first lens 22
is same as that of the annular groove 235 of the second lens 23.
[0018] The spacer 24 is annular shaped , and received in the lens
barrel 21. The spacer 24 is disposed between the first lens 22 and
the second lens 23. An outer diameter of the spacer 24 is same as
or slightly greater than an outer diameter of the annular grooves
225, 235, and an inner diameter of the spacer 24 is equal to or
slightly smaller than an inner diameter of the annular grooves 225,
235. One surface of the spacer 24 resists the bottom surface 227
of the annular groove 225 of the first lens 22, an opposite surface
of the spacer 24 resists the bottom surface 237 of the annular groove
235 of the second lens 23.
[0019] The IR-cut filter 25 can prevent incident infrared light
rays from reaching an image pick-up sensor in the digital camera.
The IR-cut filter 25 is received in the bottom of the lens barrel
21.
[0020] Referring now to FIG. 2, in assembling the lens module 20,
the first lens 22 is inserted into the lens barrel 21 via the open
end 212 of the lens barrel 21. The outer peripheral surface 221
tightly engages with an inner peripheral surface 218 of the lens
barrel 21. Then, the spacer 24 is received into the lens barrel
21 via the open end 212 of the lens barrel 21, and inserted into
the annular groove 225 of the first lens 22. An outer peripheral
surface of the spacer 24 tightly engages with the inner peripheral
surface 226 of the first lens 22, and supports the first lens 22.
The second lens 23 is placed in the lens barrel 21 fitting against
and receiving the spacer 23 into the annular groove 235 of the second
lens 23. The outer peripheral surface of the spacer 24 also tightly
engages with the inner peripheral surface 236 of the second lens
23. Lastly, the IR-cut filter 25 is received in the lens barrel
21, and an outer peripheral surface of the IR-cut filter 25 tightly
engages with the inner peripheral surface 218 of the lens barrel
21.
[0021] Referring to FIG. 3, a lens module 30 according to a second
preferred embodiment of the present invention is shown. The lens
module 30 includes a lens barrel 31, a first lens 32, a second lens
33, a spacer 34, and an IR-cut filter 35. In this embodiment, the
lens barrel 31, and the IR-cut filter 35 are same as the lens barrel
21 and the IR-cut filter 25 in the first embodiment. The first lens
32 has a first annular protrusion 322 in a bottom mounting surface
321 thereof. The second lens 33 has a second annular protrusion
332 in a top mounting surface 331 facing the bottom mounting surface
321 of the first lens 32. The spacer 34 has two annular grooves
342, 344 respectively defined in two surfaces thereof, corresponding
to the annular protrusions 322, 332. In assembly, the annular protrusions
322, 332 of the first lens 32, and the second lens 33 are respectively
inserted into the annular grooves 342, 344 of the spacer 34 to achieve
the alignment of the optical axes of the first lens 32 and the second
lens 33.
[0022] Additionally, an AR-Coating (anti-reflective coating) can
be provided on at least one of the aspheric surfaces of the first
lens 222. The AR-Coating is typically a thin film that includes
alternately stacked layers of silicon dioxide (SiO2) and tantalum
pentoxide (Ta2O5). Therefore, the light transmittance ratio of the
first lens 22 is increased, and the reflectivity of the first lens
22 is decreased. Furthermore, the IR-cut filter 25 can be omitted,
and an IR-Cut coating can be provided on at least one of the aspheric
surfaces of the second lens 23. The spacer 24 can be other orientation
means.
[0023] In alternative embodiments, the number of the lens in the
lens barrel can be three or more. Also, the number of the spacer
23 can be two or more dependent on the number of the lens.
[0024] Compared with other lens modules, the spacer 24 does not
directly contact with the lens barrel 21. Thus, the round tolerance
of the lens barrel 21 has nothing with the spacer 24. Therefore,
the optical axes of the first lens 22 and the second lens 23 are
reliably aligned to a greater accuracy since a spacer 24 is adopted
to determine not only the alignment of optical axes of the lenses
22, 23, but also orientation of the first lens 22 and the second
lens 23. Accordingly, an image quality of the digital camera with
the lens module is increased.
[0025] 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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