U.S. patent application number 13/792137 was filed with the patent office on 2013-10-03 for miniature mems autofocus zoom camera module.
This patent application is currently assigned to DIGITALOPTICS CORPORATION. The applicant listed for this patent is DIGITALOPTICS CORPORATION. Invention is credited to Dalit Bahar, Mark Harland, Uri Kinrot, Moshe Kriman, Moshe Levy, Ariel Lipson, Ocie Ward.
Application Number | 20130258140 13/792137 |
Document ID | / |
Family ID | 48140098 |
Filed Date | 2013-10-03 |
United States Patent
Application |
20130258140 |
Kind Code |
A1 |
Lipson; Ariel ; et
al. |
October 3, 2013 |
Miniature MEMS Autofocus Zoom Camera Module
Abstract
An autofocus zoom miniature MEMS camera module includes a
housing with an aperture for capturing digital images, an image
sensor, and an optical assembly. The optical assembly includes at
least one fixed lens group, at least one movable lens group, and a
MEMS actuator that is configured to move the movable lens group
along an optical axis of the camera module relative to the image
sensor and the fixed lens group. The MEMS actuation of the movable
lens group automatically focuses an object at a determined zoom
disposed an arbitrary distance from the camera module onto the
image sensor.
Inventors: |
Lipson; Ariel; (Tel-Aviv,
IL) ; Kinrot; Uri; (Tel-Aviv, IL) ; Bahar;
Dalit; (Tel-Aviv, IL) ; Kriman; Moshe;
(Tel-Aviv, IL) ; Levy; Moshe; (Tel-Aviv, IL)
; Ward; Ocie; (Petaluma, CA) ; Harland; Mark;
(Hilton, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DIGITALOPTICS CORPORATION |
San Jose |
CA |
US |
|
|
Assignee: |
DIGITALOPTICS CORPORATION
San Jose
CA
|
Family ID: |
48140098 |
Appl. No.: |
13/792137 |
Filed: |
March 10, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61609293 |
Mar 10, 2012 |
|
|
|
61643331 |
May 6, 2012 |
|
|
|
Current U.S.
Class: |
348/240.3 |
Current CPC
Class: |
G02B 7/09 20130101; G03B
5/00 20130101; H04N 5/2257 20130101; G02B 26/0833 20130101; G03B
3/10 20130101; H04N 5/23212 20130101; G02B 13/009 20130101; G03B
2205/0046 20130101; G03B 13/36 20130101; H04N 5/23296 20130101;
G03B 2205/0053 20130101 |
Class at
Publication: |
348/240.3 |
International
Class: |
G02B 13/00 20060101
G02B013/00; H04N 5/232 20060101 H04N005/232 |
Claims
1. An autofocus zoom miniature MEMS camera module, comprising: a
housing with an aperture for capturing digital images, an image
sensor, at least one fixed lens group, at least one movable lens
group, and a MEMS actuator that is configured to move the movable
lens group along an optical axis of the camera module relative to
the image sensor and the fixed lens group to automatically focus an
object at a determined zoom disposed an arbitrary distance from the
camera module onto the image sensor.
2. The autofocus zoom miniature MEMS camera module of claim 1,
wherein the movable lens group comprises one or more movable lenses
disposed nearest an object end of the optical path that are movable
along the optical axis of the camera.
3. The autofocus zoom miniature MEMS camera module of claim 2,
wherein the fixed lens group comprises one or more fixed lenses
disposed between the movable lens group and the image sensor that
are fixed in position relative to the image sensor, housing or a
substrate to which the image sensor is coupled, or combinations
thereof.
4. The autofocus zoom miniature MEMS camera module of claim 3,
wherein the image sensor is disposed approximately at a back focal
length of the one or more fixed lenses.
5. The autofocus zoom miniature MEMS camera module of claim 4,
wherein the one or more fixed lenses are configured to compensate
for a field curvature induced by the one or more moving lenses.
6. The autofocus zoom miniature MEMS camera module of claim 4,
wherein the one or more fixed lenses are configured to match an
associated point spread function to a pixel dimension of the image
sensor approximately uniformly over an area of the image
sensor.
7. The autofocus zoom miniature MEMS camera module of claim 4,
wherein the one or more fixed and movable lenses are configured
such that an autofocus distance range comprises 10 cm to 9 m.
8. The autofocus zoom miniature MEMS camera module of claim 4,
wherein the one or more fixed and movable lenses are configured
such that an autofocus distance range comprises 15 cm to 5 m.
9. The autofocus zoom miniature MEMS camera module of claim 4,
wherein the one or more fixed and movable lenses are configured
such that an autofocus distance range comprises 20 cm to 3 m.
10. The autofocus zoom miniature MEMS camera module of claim 19,
wherein the autofocus distance excludes a hyperfocal distance.
11. An optical assembly for an autofocus zoom miniature MEMS camera
module, comprising: a housing with an aperture, at least one fixed
lens group, at least one movable lens group within the housing, and
a MEMS actuator that is configured to move the movable lens group
along an optical axis of the camera module relative to the fixed
lens group to automatically focus an object at a determined zoom
disposed an arbitrary distance from the camera module onto an image
sensor when the housing is coupled to an image sensor
component.
12. The optical assembly for an autofocus zoom miniature MEMS
camera module of claim 11, wherein the movable lens group comprises
one or more movable lenses disposed nearest an object end of the
optical path that are movable along the optical axis.
13. The optical assembly for an autofocus zoom miniature MEMS
camera module of claim 12, wherein the fixed lens group comprises
one or more fixed lenses disposed between the movable lens group
and the image sensor that are fixed in position relative to the
image sensor, housing or a substrate to which the image sensor is
coupled, or combinations thereof.
14. The optical assembly for an autofocus zoom miniature MEMS
camera module of claim 13, wherein the image sensor is disposed
approximately at a back focal length of the one or more fixed
lenses.
15. The optical assembly for an autofocus zoom miniature MEMS
camera module of claim 11, wherein the one or more fixed lenses are
configured to compensate for a field curvature induced by the one
or more moving lenses.
16. The optical assembly for an autofocus zoom miniature MEMS
camera module of claim 11, wherein the one or more fixed lenses are
configured to match an associated point spread function to a pixel
dimension of the image sensor approximately uniformly over an area
of the image sensor.
17. The optical assembly for an autofocus zoom miniature MEMS
camera module of claim 11, wherein the one or more fixed and
movable lenses are configured such that an autofocus distance range
comprises 10 cm to 9 m.
18. The optical assembly for an autofocus zoom miniature MEMS
camera module of claim 11, wherein the one or more fixed and
movable lenses are configured such that an autofocus distance range
comprises 15 cm to 5 m.
19. The optical assembly for an autofocus zoom miniature MEMS
camera module of claim 11, wherein the one or more fixed and
movable lenses are configured such that an autofocus distance range
comprises 20 cm to 3 m.
20. The optical assembly for an autofocus zoom miniature MEMS
camera module of claim 19, wherein the autofocus distance excludes
a hyperfocal distance.
Description
PRIORITY
[0001] This application claims the benefit of priority to U.S.
provisional patent application Ser. Nos. 61/609,293, filed Mar. 10,
2012(Docket: IO2-0382-US-01); and 61/643,331, filed May 6, 2012
(Docket: IO2-0382-US-02), which are incorporated by reference.
[0002] This application is one of a group of related,
contemporaneously-filed patent applications by the same Assignee
and Inventors, entitled: MINIATURE CAMERA MODULE WITH MEMS-ACTUATED
AUTOFOCUS (Docket: IO2-0382-US-03); MINIATURE MEMS AUTOFOCUS ZOOM
CAMERA MODULE (Docket: IO2-0382-US-04); CAMERA MODULE WITH MEMS
AUTOFOCUS AND ZOOM (Docket: IO2-0382-US-05); MEMS AUTOFOCUS CAMERA
MODULE WITH ALIGNMENT REGISTRATION (Docket: IO2-0382-US-06); CAMERA
MODULE WITH PROCESSOR-BASED MEMS-ACTUATED AUTOFOCUS (Docket:
IO2-0382-US-07); MEMS AUTOFOCUS CAMERA MODULE WITH MULTIPLE LENS
GROUPS (Docket: IO2-0382-US-08); MEMS AUTOFOCUS CAMERA MODULE WITH
FIXED AND MOVABLE LENS GROUPS (Docket: IO2-0382-US-09), which are
incorporated by reference.
BACKGROUND
[0003] 1. Field of the Invention
[0004] The present application is related to electronic cameras and
more particularly, to electronic cameras with autofocus and/or
zoom, and particularly having optical and electrical integration of
autofocus and/or zoom components.
[0005] 2. Description of the Related Art
[0006] If the position of an optical train of a camera is fixed
relative to the position of the image sensor, the resulting
electronic camera is said to be fixed focus. Rigidly fixing the
optical system in place means only objects that are a certain
distance from the camera will be in focus on the image sensor.
Fixed focus cameras have advantages in terms of smallness of
physical dimensions and cost, but the performance is limited. In
particular, the focus distance is often set at 1.2 m so that
objects from 60 cm to infinity appear tolerably sharp. However, the
image sharpness is not especially good and objects that are closer
to the camera than 60 cm will be blurred.
[0007] While it is possible to set the focus at a closer distance
to correct for this problem, this means that the sharpness of
distant objects declines in compensation. A characteristic that is
common to both conventional fixed and auto focus cameras is that
the area that can be viewed, known as the field of view of the
camera, is determined by the optical design and the dimensions of
the image sensor and cannot be changed. For convenience, field of
view is often described as the equivalent solid angle in the
horizontal, vertical or diagonal plane.
[0008] Cropping an image to reduce the field of view has advantages
that it entails no moving parts, can be performed almost
instantaneously and involves very low power and physical space to
implement. It is a relatively low cost method of changing the field
of view. However cropping involves the loss of information. That
is, to restrict the field of view, an image is cropped to, say, one
quarter of its original area, such that three quarters of the image
is discarded. Consequently, a cropped image can often have inferior
quality to both the original image and a mechanical zoom image of
the same field of view.
[0009] Generally, the lower the quality of the optical train, the
larger the PSF or point spread function will be. In many
conventional cameras, the optical train tends to be underspecified,
such that points of captured light spread excessively to cover
several pixels resulting in blurred images.
[0010] Lenses may be assembled in a lens turret to form an optical
train. In a conventional method, a lens turret may be fabricated
first, after which the lenses may be inserted, and then fixed in a
desired location inside the lens turret. Methods of enhanced
precision are desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates schematically certain components of an
optical train of an auto focus zoom camera in accordance with
embodiments, including fixed and moving lens groups for imaging a
scene onto an image sensor.
[0012] FIGS. 2A-2B illustrate center and tilt misalignments,
respectively, between the fixed and moving lens groups of an auto
focus zoom camera in accordance with certain embodiments.
[0013] FIGS. 3A-3B illustrate camera module guide pins in
accordance with certain embodiments, shown in section and plan view
(inset).
[0014] FIGS. 4A-4B illustrate a circular sleeve in accordance with
embodiments in section and plan views.
[0015] FIGS. 4C-4G illustrate a selection of sleeves for guide pins
that may be used in certain embodiments.
[0016] FIG. 5 illustrates an auto focus zoom camera module in
accordance with embodiments including a moving lens mounted in a
housing and the housing attached to sleeves that ride on guide
pins.
[0017] FIG. 6 depicts a detail view of an example of an optical
train in accordance with embodiments where the fixed and moving
lenses can be been aligned to each other by physical features.
[0018] FIG. 7 illustrates an auto focus zoom camera module at
intermediate state of assembly where the fixed and moving lenses
are aligned by registration features, but the housing of the moving
lenses is not attached to the sleeves.
[0019] FIG. 8 illustrates a cross-section of a completed camera
where a housing that is offset to the optical axis has been joined
to the sleeves with the fixed and moving lenses still aligned to
each other but separated by a working distance.
[0020] FIG. 9 depicts a plan view of an auto focus zoom camera
where the mechanical axis of the guide pins is offset from the
optical axis.
[0021] FIG. 10A illustrates optics for a fixed focus camera.
[0022] FIG. 10B illustrates optics for an auto-focus camera.
[0023] FIG. 10C illustrates an example of an optical train for an
autofocus zoom camera in accordance with embodiments.
[0024] FIG. 11 illustrates a section view of a camera module in
accordance with certain embodiments.
[0025] FIG. 12 illustrates a side view of the camera module of FIG.
11.
[0026] FIG. 13 illustrates the side view of the camera module of
FIG. 12 without the lenses.
[0027] FIG. 14 illustrates a top view of the camera module of FIGS.
11-13.
[0028] FIGS. 15-18 illustrate advantageous examples involving zoom
factors for camera modules in accordance with embodiments.
DETAILED DESCRIPTIONS OF THE EMBODIMENTS
[0029] A miniature MEMS autofocus camera module is provided that
includes a MEMS actuated movable lens group and at least one fixed
lens group defining an optical axis within a camera module housing
within which objects disposed an arbitrary distance from the camera
module are automatically focused at a determined zoom to an image
sensor by MEMS actuation of the movable lens group to accomplish
autofocus functionality.
[0030] The camera module may include a processor and embedded code
for programming the processor to electronically zoom the image
data. The electronic zoom may utilize both electronic and optical
processing elements. The optical autofocus may also utilize both
electronic and optical processing elements. One or more lenses may
participate as a same electronic and optical processing element
used for both the optical autofocus and the electronic zoom.
[0031] The at least one fixed lens group may include first and
second lens groups. The movable lens group may be disposed between
the first and second fixed lens groups.
[0032] An optical assembly for a miniature MEMS autofocus camera
module is also provided including a MEMS actuated movable lens
group and at least one fixed lens group defining an optical axis
within a housing configured to couple with an image sensor
component to capture digital images of objects disposed an
arbitrary distance from the camera module that are automatically
focused at a determined zoom to an image sensor portion of the
image sensor component by MEMS actuation of the movable lens group
to accomplish autofocus functionality.
[0033] The optical assembly may include contact pads for coupling
with a processor programmed to electronically zoom the image data.
The electronic zoom may utilize both electronic and optical
processing elements. The optical autofocus may also utilize both
electronic and optical processing elements. One or more lenses may
participate as a same electronic and optical processing element
used for both the optical autofocus and the electronic zoom.
[0034] The at least one fixed lens group may include first and
second lens groups. The movable lens group may be disposed between
the first and second fixed lens groups.
[0035] An autofocus zoom miniature MEMS camera module is provided
that includes a housing with an aperture for capturing digital
images, an image sensor and an optical assembly. The optical
assembly is provided with at least one fixed lens group and at
least one movable lens group. A MEMS actuator is configured to move
the movable lens group along an optical axis of the camera module
relative to the image sensor and the fixed lens group to
automatically focus an object at a determined zoom disposed an
arbitrary distance from the camera module onto the image
sensor.
[0036] The movable lens group may include one or more movable
lenses disposed nearest an object end of the optical path that are
movable along the optical axis of the camera. The fixed lens group
may include one or more fixed lenses disposed between the movable
lens group and the image sensor that are fixed in position relative
to the image sensor, housing or a substrate to which the image
sensor is coupled, or combinations thereof.
[0037] The image sensor may be disposed approximately at a back
focal length of the one or more fixed lenses. The one or more fixed
lenses may be configured to compensate for a field curvature
induced by the one or more moving lenses. The one or more fixed
lenses may be configured to match an associated point spread
function to a pixel dimension of the image sensor approximately
uniformly over an area of the image sensor. The one or more fixed
and movable lenses may be configured such that an autofocus
distance range comprises 10 cm to 9 m. The one or more fixed and
movable lenses may be configured such that an autofocus distance
range comprises 15 cm to 5 m. The one or more fixed and movable
lenses may be configured such that an autofocus distance range
comprises 20 cm to 3 m. The autofocus distance may exclude a
hyperfocal distance.
[0038] An optical assembly for an autofocus zoom miniature MEMS
camera module is also provided that includes a housing defining an
aperture, one or more lenses that are fixed relative to the
housing, a MEMS actuator, and one or more movable optical elements
coupled to the MEMS actuator. An object disposed an arbitrary
distance from a camera module that includes the optical assembly is
automatically focused at a determined zoom onto the image sensor by
MEMS actuation of the one or more movable optical elements.
[0039] The optical assembly and/or MEMS camera module may include a
zoom feature ranging between .times.0.5 and .times.5, or between
.times.1 and .times.3.
[0040] The optical assembly may include a movable lens housing
containing the one or more movable lenses.
[0041] An optical axis of the one or more movable optical elements
may be displaced from an optical axis of the camera module by not
more than approximately 0.5 mm, or by not more than approximately
0.2 mm, or by not more than approximately 0.1 mm.
[0042] The movable and fixed lens groups may be relatively disposed
with a centering alignment within 90 microns, or in a range between
40 microns and 140 microns.
[0043] A third lens group may be fixed relative to the housing. The
movable lens group may be disposed between the first and third
fixed lens groups.
[0044] The focus travel length of the second lens group may be more
than 50, 100, 200, or 300 microns, and/or within a range between
100 microns and 300 microns or within a range between 50 microns
and 500 microns.
[0045] Another autofocus zoom miniature MEMS camera module is
provided that includes a housing, a MEMS actuator, one or more
movable optical elements coupled to the MEMS actuator, an image
sensor, a processor, and a storage medium having code embedded
therein for programming the processor to perform an autofocus zoom
method. An object disposed an arbitrary distance from the camera
module is automatically focused at a determined zoom onto the image
sensor by MEMS actuation of the one or more movable optical
elements.
[0046] The code may be configured to program the processor to
correct for distortion or another artifact produced in a
predictable manner by one or more optical elements of the camera.
The code may be configured to program the processor to process
information from image sensor pixels irrespective of a number of
pixels within an image area that are illuminated by the one or more
optical elements.
[0047] The code may be implemented in hardware or software or
both.
[0048] The processor may be configured to perform an autofocus zoom
method within an image processing pipeline on the image sensor.
[0049] The processor may be configured to perform the autofocus
zoom method on a discrete platform. The discrete platform may
include an image processor or image signal processor. The discrete
platform may include a baseband chip in a mobile phone. A machine
readable file that has largely constant size and effective image
resolution irrespective of autofocus zoom setting. The camera may
be configured with a zoom feature ranging between .times.0.5 and
.times.5, or between .times.1 and .times.4, or between .times.1 and
.times.3.
[0050] A movable lens housing may contain the one or more movable
lenses. The movable lens housing may be configured to be movable
mechanically along the optical axis of the camera. The MEMS
actuator or another actuator may be configured to move the movable
lens housing along the optical axis. The movable lens housing may
include one or more guide pins and one or more sleeves configured
such that the guide pins are fixed in position while the sleeves
move along the guide pins.
[0051] The guide pins may be mechanically referenced to the image
sensor and the sleeves may be joined to the movable lens housing.
The guide pins may include two or more guide pins, or three or more
guide pins, or five or more guide pins. The guide pins may include
a circular cross section. The one or more sleeves may include a
shape, when viewed in section, that forms one or more area contacts
to the guide pins. The shape of the one or more sleeves may include
an oval shape, a "V" shape, a triangular shape, a square shape, a
pentagon shape, a hexagon shape, and/or another polygon shape,
e.g., a regular polygon, or an irregular polygon, or the one or
more sleeves may have a circular shape.
[0052] The one or more sleeves may be configured to be forced into
contact with the one or more guide pins by a lateral force. The
lateral force may include approximately 0.5 grams. A spring may be
used to provide the lateral force. A magnet may be used to provide
the lateral force.
[0053] A movable housing may include one or more guide pins and one
or more flexible components that are flexible in a direction along
the optical axis. The guide pins may be fixed in position while the
flexible components move along the guide pins. The one or more
flexible components may include leaf springs that are fixedly
attached to the guide pins and the movable lens housing. The one or
more flexible components may include one or more opposing pairs
having a spring rate that is approximately constant through a
flexure range.
[0054] The camera module housing and image sensor may define an
optical axis of the MEMS camera module. An axis of the one or more
movable optical elements may be displaced from the optical axis of
the MEMS camera module by not more than approximately 0.5 mm, or by
not more than approximately 0.2 mm, or by not more than
approximately 0.1 mm.
[0055] The MEMS actuator may be configured to move the one or more
movable lenses within a range between 50 and 500 microns, or within
a 350 micron range, or within a 200 micron range.
[0056] A method of assembly of a miniature MEMS camera module is
provided. The method includes abutting registration features of an
optical assembly that includes both a fixed lens group and a
movable lens group including one or more movable lenses, and
affixing the movable lens group in location within a movable lens
housing. A MEMS actuator is coupled to the movable lens group or
housing or both, whereby in use the MEMS actuator is configured to
move the movable lens group relative to the fixed lens group to
automatically adjust a focus distance of the optical assembly.
[0057] The affixing may involve applying an adhesive. The applying
an adhesive may include joining the movable lens housing to a
sleeve that is configured to couple with a pin that is fixed to the
miniature camera module.
[0058] The method may include coupling the optical assembly with an
image sensor component, which may involve fixing the fixed lens
group relative to an image sensor portion of the image sensor
component while the movable lens group or movable lens housing or
both is configured to be movable relative to the image sensor
portion by actuation of the MEMS actuator to adjust said focus
distance of the optical assembly. The method may further include
coupling the image sensor component to a printed circuit.
[0059] The miniature MEMS camera module, upon assembly, may defines
an optical axis that is displaced from an axis of the movable lens
group not more than approximately 0.5 mm, or not more than
approximately 0.2 mm, or not more than approximately 0.1 mm.
[0060] A miniature MEMS autofocus camera module is also provided
that includes a housing, an image sensor coupled to the housing, an
autofocus optical module coupled within the housing and including a
MEMS actuator that is configured to move one or more movable lenses
relative to one or more fixed lenses along an optical axis of the
camera module to adjust a focusing distance of the autofocus
optical module to automatically focus an object disposed an
arbitrary distance from the camera module onto the image sensor.
This miniature MEMS autofocus optical module includes one or more
pairs of adjacent lens surfaces that include abutting registration
features to aid in alignment. An optical assembly for the
aformentioned miniature MEMS autofocus camera module is also
provided.
[0061] The one or more movable lenses may be disposed nearest an
object end of the optical path between a housing aperture and the
image sensor. The one or more fixed lenses may include at least a
first fixed lens disposed between the one or more movable lenses
and the image sensor. The image sensor may be disposed
approximately at a back focal length of the first fixed lens.
[0062] The one or more fixed lenses may include at least a second
fixed lens disposed between the object end and the one or more
movable lenses, such that the one or more movable lenses are
disposed between the first and second fixed lenses. The second
fixed lens may be configured in accordance with a
processor-implemented zoom component to apply zoom to captured
image data.
[0063] The miniature MEMS camera module, upon assembly, may define
an optical axis that is displaced from an axis of the movable lens
group not more than approximately 0.5 mm, or not more than
approximately 0.2 mm, or not more than approximately 0.1 mm. The
one or more fixed lenses may include first and second fixed lens
groups each comprising one or more lenses that are fixed relative
to the image sensor. The one or more movable lenses may be disposed
between the first and second fixed lens groups.
[0064] A miniature MEMS autofocus camera module is also provided
that includes an image sensor and an optical assembly including a
movable lens group that includes one or more lenses and that is
coupled to a MEMS actuator such that the movable lens group is
movable relative to the image sensor. The optical assembly also
includes at least a first fixed lens group that comprises one or
more lenses and that is fixed relative to the image sensor. A
processor is programmed to control an autofocus method designed to
adjust a focus distance to an object disposed an arbitrary distance
from the miniature MEMS autofocus camera module by actuating the
MEMS actuator that is coupled with the movable lens group.
[0065] The optical assembly may include a second fixed lens group
that includes one or more lenses that are fixed relative to the
image sensor. The movable lens group may be disposed between the
first and second fixed lens groups.
[0066] A first surface of the one or more fixed lenses furthest
from the image sensor and a second surface of the one or more
movable lenses nearest to the image sensor may be provided with one
or more physical registration features configured to abut to aid
alignment during assembly.
[0067] A spacer may be disposed between the first and second
surfaces. The spacer may have been inserted for operation after
assembly. The absence of the spacer during assembly may have
permitted the registration features of the first and second
surfaces to abut. The spacer may be configured to achieve a
separation in a range between 50 and 500 microns, or in a range
between 50 and 150 microns, or in a range between 200 and 300
microns, or the spacer may be configured to achieve a separation of
approximately 100 microns, or approximately 250 microns.
[0068] The optical assembly may include one or more pairs of
adjacent lens surfaces that include abutting registration
features.
[0069] The miniature MEMS camera module, upon assembly, may define
an optical axis that is displaced from an axis of the movable lens
group not more than approximately 0.5 mm, or not more than
approximately 0.2 mm, or not more than approximately 0.1 mm.
[0070] In operation of the autofocus zoom module, a registration of
de-center between the one or more fixed lenses and the one or more
moving lenses may be approximately seven microns or less, or
approximately five microns or less, or approximately three microns
or less.
[0071] In operation of the autofocus zoom module, a registration of
tilt between the one or more fixed lenses and the one or more
moving lenses may be approximately 0.3 microns or less, or
approximately 0.2 microns or less, or approximately 0.1 microns or
less.
[0072] An optical assembly for a miniature MEMS camera module may
include an optical assembly housing, configured for coupling with
an image sensor component, and an autofocus optical module coupled
within the housing. The autofocus optical module includes a MEMS
actuator that is configured to move one or more movable lenses
relative to one or more fixed lenses along an optical axis to
adjust a focusing distance of the autofocus optical module.
[0073] The one or more movable lenses may be disposed nearest an
object end of the optical path and may be movable along the optical
axis. The one or more fixed lenses may be disposed nearest an image
end of the optical path and may be fixed in position relative to
the housing. The optical assembly housing may be configured to
couple with an image sensor portion of the image sensor component
that is disposed approximately at a back focal length of the one or
more fixed lenses.
[0074] The one or more fixed lenses may include first and second
fixed lens groups each having one or more lenses that are fixed
relative to the housing. The one or more movable lenses may be
disposed between the first and second fixed lens groups. The
optical assembly may include one or more pairs of adjacent lens
surfaces that include abutting registration features. The optical
assembly, upon assembly with an image sensor component, may define
an optical axis that is displaced from an axis of the movable lens
group not more than approximately 0.5 mm, or not more than
approximately 0.2 mm, or not more than approximately 0.1 mm.
[0075] The optical assembly and an image sensor component may be
coupled to form an autofocus camera module, whereby a registration
of de-center between the one or more fixed lenses and the one or
more moving lenses comprises approximately seven microns or less,
or approximately five microns or less, or approximately three
microns or less.
[0076] A registration of tilt between the one or more fixed lenses
and the one or more moving lenses of the optical assembly may
comprise approximately 0.3 microns or less, or approximately 0.2
microns or less, or approximately 0.1 microns or less.
[0077] A further miniature MEMS autofocus camera module is provided
that includes an image sensor and an optical assembly including a
movable lens group that includes one or more lenses and that is
coupled to a MEMS actuator such that the movable lens group is
movable relative to the image sensor. The optical assembly further
includes at least a first fixed lens group that includes one or
more lenses and that is fixed relative to the image sensor. In
operation of the miniature MEMS autofocus camera module, a
registration of de-center between the one or more fixed lenses and
the one or more moving lenses comprises approximately seven microns
or less.
[0078] A first surface of a first fixed lens of the first fixed
lens group and a second surface of a first movable lens of the
movable lens group may be provided with one or more physical
registration features configured to abut to aid alignment.
[0079] A first surface of the one or more fixed lenses furthest
from the image sensor and a second surface of the one or more
movable lenses nearest to the image sensor may be provided with one
or more physical registration features configured to abut to aid
alignment.
[0080] In operation of the autofocus zoom module, a registration of
de-center between the one or more fixed lenses and the one or more
moving lenses may comprise approximately five microns or less, or
approximately three microns or less.
[0081] In operation of the autofocus zoom module, a registration of
tilt between the one or more fixed lenses and the one or more
moving lenses comprises approximately 0.3 microns or less, or
approximately 0.2 microns or less, or approximately 0.1 microns or
less.
[0082] A spacer may be disposed between the first and second
surfaces. The spacer may have been inserted for operation after
assembly. The absence of the spacer during assembly may have
permitted the registration features of the first and second
surfaces to abut. The spacer may be configured to achieve a
separation in a range between 50 and 500 microns, or in a range
between 50 and 150 microns, or in a range between 200 and 300
microns, or the spacer may be configured to achieve a separation of
approximately 100 microns, or approximately 250 microns.
[0083] Another miniature MEMS-actuated camera module is provided
that includes one or both of a camera module housing or a rigid
substrate that either defines an aperture or is coupled to an
aperture, or both. An image sensor is coupled to the one or both of
the camera module housing or rigid substrate. A first lens group is
coupled to the housing and fixed relative to the image sensor or
coupled directly to the image sensor or both. A MEMS actuator is
coupled to the housing or rigid substrate. A second lens group is
coupled to the actuator and is movable relative to the image
sensor.
[0084] An optical assembly for the miniature MEMS camera module may
include a housing that either defines an aperture or is coupled to
an aperture, or both, and that is configured to couple with an
image sensor component for focusing images with said optical
assembly onto an image sensor portion of said image sensor
component when said housing is coupled to said image sensor
component, a first lens group coupled to and fixed relative to the
housing, a MEMS actuator coupled to the housing, and a second lens
group coupled to and movable with the MEMS actuator relative to the
first lens group.
[0085] A rigid substrate may be coupled to the camera module
housing.
[0086] A lens barrel may contain at least the second lens
group.
[0087] The MEMS actuator may be coupled to one, two, three, four or
more lenses of the second lens group for moving the one, two,
three, four or more lenses along the optical path relative to the
image sensor.
[0088] The second lens group may include four lenses. The first
lens group may include a single lens.
[0089] The second lens group may include a single movable lens. The
first lens group may include two fixed lenses. A third lens group
may include one or two more fixed lenses. The second lens group may
be disposed and movable through an autofocus range between the
first and third fixed lens groups.
[0090] The first and second lens groups may be relatively disposed
with a centering alignment within 1 micron, or within 3 microns, or
within 5 microns, or within 10 microns.
[0091] The first and second lens groups may be relatively disposed
with a tilt alignment within of 0.01.degree., or within
0.05.degree., or within 0.1.degree., or within 0.2.degree., or
within 0.3.degree., or within 0.4.degree..
[0092] The first and second lens groups may be relatively disposed
within a centering alignment in a range between of 1 micron and 10
microns, or in a range between 2 microns and 5 microns.
[0093] The first and second lens groups may be relatively disposed
within a tilt alignment in a range between 0.05.degree. and
0.3.degree., or in a range between 0.1.degree. and 0.2.degree.. The
focus travel length of the second lens group may be more than 50
microns, or more than 100 microns, or more than 150 microns, or
more than 200 microns, or more than 250 microns, or more than 300
microns, or within a range between 100 microns and 300 microns, or
within a range between 50 microns and 500 microns.
[0094] The first lens may be disposed a distance from the sensor
along the optical path within a range between around its back focal
length.+-.10 microns. The back focal length may include between 700
and 1100 microns, or between 500 and 1300 microns, or approximately
900 microns.
[0095] The second lens group and image sensor may be relatively
disposed with a centering alignment within 90 microns, or in a
range between 40 microns and 140 microns.
[0096] A third lens group may be coupled to the housing and fixed
relative to the image sensor. The second lens group which is
movable relative to the image sensor may be disposed between the
first and third lens groups which are each fixed relative to the
image sensor.
[0097] A camera in accordance with embodiments described herein
includes an image sensor, which converts an image in an optical
domain to an electronic format, and an optical train that focuses
the scene of interest onto the image sensor. Embodiments include
cameras configured with an enhanced ability to accurately capture
detail in a scene. The quality of the optical train and/or the
resolution of the image sensor may be selected in accordance with a
desired ability to accurately capture such detail. The image sensor
may contain millions of pixels (picture elements) and the optical
train may include two, three, four, five or more lenses.
[0098] The position of at least one movable lens of the optical
train is not fixed relative to the position of the image sensor,
and thus, cameras in accordance with embodiments described herein
can alter the distance from the electronic camera at which objects
will be in focus on the image sensor. A system may be utilized in
accordance with certain embodiments to determine one or more
distances of one or more principal objects in a scene from the
camera. The at least one movable lens is movable in accordance with
the determined distance in certain embodiments and/or until one or
more principle objects are in focus on the image sensor. These
objects can range from being very close (10 cm or closer) to very
distant (infinity) from the camera.
[0099] Embodiments are provided herein of cameras that provide
image quality that is better than conventional autofocus and fixed
focus cameras. Cameras in accordance with certain embodiments also
exhibit miniature size, as well as advantageous power
efficiency.
[0100] Electronic cameras in accordance with certain embodiments
exhibit an advantageous capability to alter the field of view
significantly. For example, a photograph of a family taken in front
of their house might inadvertently include a refuse container at
the edge of the scene when a conventional camera is being used. A
camera in accordance with certain embodiments can be adjusted to
restrict the field of view of the camera to eliminate this artifact
from the captured image. Conversely, a photograph of a family taken
on top of a hill can be enhanced using a camera in accordance with
certain embodiments by adjusting to a wider field of view that
captures more of the panorama.
[0101] It is possible to alter the field of view of an electronic
camera in accordance with certain embodiments in multiple ways. One
way is to alter an aspect of the optical system, e.g., using zoom
capability, whereby one or two or more and in some embodiments four
or more lenses, and/or one or more apertures, is/are movable back
and forth along the optical axis of the camera.
[0102] Another way of changing the field of view of an electronic
camera in accordance with certain embodiments is to crop, delete
and/or clip peripheral regions of the captured scene when it is in
electronic format, although cropping is subject to the limitations
described above involving the discarding of peripheral image data.
However, because a cropped image is smaller than the original, it
can be electronically expanded so that it is the equivalent size as
the original but, because parts of the scene are now absent, the
effective field of view is diminished.
[0103] Another method of accomplishing zoom in an electronic camera
in accordance with certain embodiments exploits matching the
so-called point spread function of the optical train to the image
sensor. Point spread function (PSF) can be defined as a quantity
that describes the extent to which a theoretical point of light of
zero area would expand as it passes through the optical train of
the camera and/or would spread out by viewing, optical quality,
diffraction, following up on accuracy, and/or the resolution of the
sensor. The expansion occurs due to defects in the materials used
for the lenses, surface imperfections, alignment tolerances and/or
potentially a host of other factors. A good match between the
optical train and image sensor occurs when the PSF matches the
dimensions of the pixels in the image sensor. If the optical train
is over-specified, the point of light will spread slightly and
remain smaller than one pixel.
[0104] In certain embodiments, the PSF of the optical train does
not vary significantly with the radius. This electronic camera has
no significant mismatch between the PSF and pixel size across the
lens radius. In some embodiments, the pixels in the center are
smaller than those at the periphery to match the variation in PSF
function across the lens radius.
[0105] In certain embodiments, the PSF is set to match the pixel
size at about two thirds of the lens radius, particularly when it
is determined that the objects of greatest interest in the scene
are in the center of the image.
[0106] In an alternative embodiment, an optical train is designed
so that at the periphery the PSF matches the pixel size of the
imager. This optic design is adjusted as it is continued inwards,
so that it results in the lens being over-specified since the PSF
decreases towards the optical axis. In certain embodiments, the
magnification of the optical system is increased towards the
center. This magnification increases the effective size of the
point of light and hence the effective PSF. The magnification may
be set to be sufficient so that the PSF matches the pixel size over
the entire area of the imager. The result is the lens has higher
magnification in the center than at the periphery.
[0107] An electronic camera using an optic of the type described is
able to provide for dynamic alteration of the field of view, in
other words zoom, by imaging cropping. The resolution of the
cropped image advantageously does not diminish since the center of
the image has been magnified by the lens. The special optic
involved in producing a dynamic field of view camera in accordance
with certain embodiments generally produces distortion of the image
that resembles barrel distortion. The extent of the distortion is
fixed and controlled by the lens design. In certain embodiments,
this distortion is corrected and removed, along with potentially
one or more other predictable artifacts, using an advantageous
image processing technique incorporated in a camera system in
accordance with certain embodiments that has code embedded within a
digital storage device for programming a camera processor to
perform the technique and generate modified image data.
[0108] Cameras in accordance with certain embodiments exhibit clear
improvements in overall performance by incorporating dynamic field
of view feature with an auto focus mechanism. In certain
embodiments, the design of the optical train of the camera includes
a part that is fixed and a part that is movable along the optical
axis of the camera by an actuator. In certain embodiments, some
image processing is provided by code embedded within a fixed or
removable storage device on the camera and/or using a remote
processor, e.g., removal of image distortion.
[0109] Advantageous cameras are provided in accordance with certain
embodiments that integrating all three of these in a compact camera
module. Such camera module may be a stand-alone camera product, or
may be included in a fixed or portable electronics product, and/or
in various other environments such as automobiles.
[0110] Several embodiments will now be described with reference to
the figures. Electronic cameras are provided herein that
advantageously incorporate integrated auto focus and zoom
functionality. In certain embodiments, the autofocus and zoom
functions utilize a combination of an advantageous optical train
and processor-based image processing, and in certain embodiments
include the same or similar components in both cases.
[0111] An optical train in accordance with certain embodiments that
is able to realize the desired functions of auto focus and zoom
includes two general components (see FIG. 1). These are a first
lens group 101 of one or more lenses that can be moved 102 along
the optical axis 103 of the camera (hereafter referred to as the
"moving lens") and a second lens group 104 of one or more lenses
that are fixed in position (hereafter referred to as the "fixed
lens"). The moving lens is the lens closest to scene 105 and the
fixed lens is the lens closest to the imager 106. In general terms,
the moving lens performs the function of altering the focal
distance of the camera and the fixed lens performs the function of
matching the PSF function of the optic to the imager and
compensating for the field curvature induced by the moving
lens.
[0112] The moving lens is located at an appropriate distance along
the optical axis to achieve the desired focus distance, while the
fixed lens is located such that its back focal length matches the
distance between the lens and the imager.
[0113] A processor programmed by embedded code collects information
from pixels in the image sensor and makes changes to the associated
electronic file, in some cases automatically and in others based on
user inputs. For example, the degree of zoom is adjustable. The
processor endeavors to correct for distortion and other artifacts
that are produced in a predictable manner by the optical train. The
image processing features can be implemented in either hardware or
software. In certain embodiments, these features are placed early
in the image processing pipeline, such as RTL (resistor transistor
logic) code embedded in the image sensor, while in others they are
placed on an external DSP (digital signal processor) or entirely in
software in a processor, such as the base band chip in a mobile
phone.
[0114] The resulting auto focus zoom camera example illustrated at
FIG. 1 has a focus distance that can range 10 cm to 9 m, is
typically 15 cm to 5 m and is preferably 20 cm to 3 m (excluding
the hyper-focal distance), while the zoom function can range
.times.0.5-.times.5, is typically .times.1-.times.4 and is
preferably .times.1-.times.3. A noteworthy characteristic of the
final electronic file produced by the advantageous camera
illustrated schematically at FIG. 1 is that file size and effective
resolution of the image contained within it may be largely constant
in certain embodiments irrespective of the focus distance and zoom
setting.
[0115] In contrast to traditional electronic cameras that are
either fixed focus, where no lenses move, or auto focus where the
entire optical train is moved, advantageous cameras in accordance
with embodiments described herein include optical trains with both
a movable component and a fixed component. These advantageous auto
focus zoom cameras have one or more parts of the optical train
fixed and one or more parts moving. In certain embodiments, cameras
exhibit exactitude of centering and tilt alignment of the moving
lens to the fixed lens that differs from conventional fixed or auto
focus cameras.
[0116] With reference to the example illustrated schematically at
FIG. 2: The registration of de-center between the fixed and moving
lens can range +/-7 um, is typically +/-5 um and is preferably +/-3
um. When the optical axis 201 of the camera and the fixed lens 202
is not co-incident with the optical axis 203 of the moving lens
204, de-center 205 results. The registration of tilt is between the
fixed and moving lens can range +/-0.3 um, is typically +/-0.2 um
and is preferably +/-0.1 um. When the optical axis optical axis 203
of the moving lens 204 is tilted with respect to the optical axis
201 of the camera and the fixed lens 202, tilt 206 results.
[0117] The above features may be advantageously achieved when
cameras in accordance with certain embodiments are first assembled
and then are sustained when the camera is operated, in particular
when the moving lens is intentionally displaced along the optical
axis of the camera. How these criteria are met during assembly and
operation of the camera are two further advantageous features of
cameras in accordance with embodiments described herein.
[0118] Cameras in accordance with certain embodiments are
configured to perform registration between the moving lens and the
optical axis of the camera module during operation. With reference
to FIG. 3, a camera module 301 is provided with one or more guide
pins 302 that run parallel to the optical axis 303. The optical
axis is determined by a line 305 drawn normal to the center of the
imager 306. The guide pins can number up to 5 or more, and may be
typically 2 or 3 in certain embodiments, while in another
embodiment, one guide pin is used in combination with a second
stabilization and alignment component. The one or more guide pins
may be circular in cross-section, or alternatively may be
elliptically-shaped, or may have be a regular or irregular polygon
of any number of three or more sides.
[0119] In embodiments involving multiple (i.e., two or more) guide
pins, the guide pins may be in some embodiments distributed in a
substantially equidistant fashion about the image sensor, and in
other embodiments, two guide pins are more closely spaced than a
third guide pin, and in other embodiments, two guide pins are
closer on one side than another while a second stabilization and
alignment component is also used.
[0120] To provide motion substantially or approximately solely in a
direction parallel to the optical axis, movable sleeves are placed
over the guide pins in certain embodiments, as illustrated
schematically in the example of FIG. 4. The sleeves can take many
forms, some examples being shown in FIG. 4. However, because
advantageous camera modules in accordance with certain embodiments
are configured to eliminate or significantly reduce mechanical
play, the sleeve makes physical contact with the guide pin in a
consistent and predictable manner throughout the stroke of the
moveable lens group.
[0121] In addition, miniature cameras in accordance with certain
embodiments are configured to minimize or significantly reduce
friction force between the sleeve and guide pin. This feature
advantageously assists the miniature actuator that is used to move
the movable lens group, such that the actuator can move the movable
lens group with a smaller applied motive force than if greater
friction were present.
[0122] Advantageous low surface friction materials, bearings and/or
other low friction components may be used. Geometries of the sleeve
that are used in certain embodiments provide a small number of
small area contact points to the guide pin. Examples include
V-grooves, triangles, squares, pentagons, hexagons, ellipses and
other regular and irregular curved shapes and polygons. Of these,
V-grooves provide the fewest, i.e., two. A V-groove in a solid
object may be realized from two faces set at an obtuse angle, such
as from two faces of a pentagon that is larger in diameter than the
guide pin, or alternatively from two faces set at an acute angle
although these acute angle embodiments have an overall larger
diameter than the obtuse angle embodiments.
[0123] In an example embodiment of a pentagon shape, in order to
ensure that the same two faces of the pentagon are in contact with
the guide pin, a further embodiment includes a mechanism or other
stabilization or alignment component that ensures a small lateral
force is always present between the pentagon and the guide pin.
This force can typically range between 0.1 gf and 5 gf
(gram-force), and may be between 0.2 gf and 2 gf and may be
approximately 0.5 gf in certain embodiments. Lateral forces of this
magnitude are advantageously developed in various embodiments using
one or more springs, compressed materials (e.g., a block of
rubber), and/or magnets.
[0124] The moving lens in several embodiments includes a group of
individual lenses, apertures and optionally other optical
components, these components are mounted together as a unitary
element within a housing. The housing in certain embodiments is
attached to one or more sleeves that couple with one or more guide
pins. An example of one of these embodiments is schematically
illustrated in FIG. 5. The fixed lenses 501 are connected to the
camera module body 502, as is the imager 503. The imager defines
the optical axis of the camera 504. The moving lenses 505 are
located in a housing 506, which is joined by a medium 507 to a
sleeve 508. The sleeves are located on the guide pins 509. Methods
of making the joints between the housing and the sleeves, both of
which include in certain embodiments polymeric materials, may
include adhesive bonding.
[0125] Various embodiments are provided that involve methods of
displacing the housing containing the moving lens group along the
optical axis. An actuator is used in certain embodiments that can
include, but is not limited to, devices that operate on principles
of the piezo-electric, electro-magnetic, electro-thermal and
electrostatic effects such as may involve a
(micro-electro-mechanical system) MEMS component. Of these, a
piezo-electric actuator may be used that delivers relatively high
force. Other actuators may be selected that deliver an extended
range of travel. The actuator is configured to deliver an
approximately minimum force to overcome the friction forces of the
sleeves against the guide pins and lift the weight of the housing,
the one or more lenses and/or other optical components that the
movable lens housing contains, against gravity.
[0126] The travel involved in many embodiments of the movable lens
group in an auto focus zoom camera module is relatively small,
e.g., in a range between 50 and 500 microns and may be in a range
around approximately 350 microns or 200 microns In certain
embodiments, an alternative to using guide pins and sleeves to
control the motion of the housing along the optical axis of the
camera involves use of components that are flexible in a direction
along the optical axis, but relatively stiff in one or more other
directions.
[0127] A leaf spring is used in certain embodiments. This
advantageous leaf spring may include a strip of metal whose length
is substantially greater than its width, which is in turn
substantially greater than its thickness. The dimensional ratios
may be around 10:1 in each case, and they are smaller or larger
than this example ratio in several embodiments. By fixing one end
of a leaf spring to a guide pin and the other end to the housing in
accordance with certain embodiments, motion is largely restricted
to being along the optical axis of the camera. In one embodiment, a
total of four leaf springs are used, with two pairs on opposing
sides of the camera housing. Where an even of leaf springs is used,
a further embodiment involves half of the springs on each side to
form an opposing pair. That is, extension of one spring results in
compression in the other. This advantageous mechanical arrangement
permits high stiffness at a low effective spring rate. The high
stiffness greatly decreases motion of the housing in undesired
directions while the low spring rate is advantageous when the
camera module includes a miniature actuator that produces a
relatively small force.
[0128] A miniature auto focus zoom camera that contains fixed and
moving lenses in accordance with certain embodiments exhibits high
image quality due to a high accuracy with which the optical
elements, notably the lenses, are manufactured and assembled as an
optical train. These optics are advantageously very close to the
computed ideal design. One reason for this is that the assembly
presents reduced risk, due to the lenses being placed to very high
precision in one or more degrees of freedom and in certain
embodiments, in five degrees of freedom. In certain embodiments,
even rotation is prohibited for lenses that are not symmetric about
the optical axis. Advantageous methods are used in assembling auto
focus zoom cameras in accordance with certain embodiments,
including high precision assembly of pre-assembled fixed and moving
lenses.
[0129] A method in accordance with certain embodiments involves
provide one or more lenses with one or more physical features that
register with significant precision with an adjacent component such
as the next lens in the optical train. Having accurately assembled
the optical train, the optical train is then inserted into a
housing. An adhesive is then applied to hold the lens train in
position in the housing.
[0130] This method is particularly advantageous when used to
assemble fixed and moving lenses and individual components,
although adjustments for building an auto focus zoom camera module
are provided in certain embodiments. The adjustments are provided
because there is a space between the fixed and moving lens group in
certain embodiments. This space can range between 50 and 500
microns, and may be in a range around approximately 250 microns in
some embodiments, and in a range around approximately 100 microns
in other embodiments. In these embodiments, the lenses do not abut
for the purposes of registration while also being separated for
operation at the same time.
[0131] Embodiments therefore include structures and a method that
are used to provide accurate alignment between fixed and moving
lenses that are separated by a gap. The basis of these embodiments
is to provide adjacent surfaces of the fixed lens and the moving
lens with physical registration features. While mating cups and
cones are provided as examples of such features herein, various
shapes and sizes of suitable alignment features may be used.
[0132] With reference to FIG. 6, the lower moving lens 601 has a
cone 602 on its image side while the upper fixed lens 603 has a cup
604 on its object side. The cones and cups can be reversed so the
cups are on the image side and the cones are on the object side.
The optical train can be aligned by stacking of the lenses so the
cups and cones nest. The cups and cones provide significantly
precise registration in plan and rotation from the object side of
the moving lens to the image side of the fixed lens. The pitch, yaw
and vertical spacing between lenses is dictated by the precision
with which the physical registration features abut. In FIG. 6, it
is the lenses themselves that are depicted as designed abutting;
however the abutting components between the fixed and moving lenses
may include additional components such as spacers.
[0133] At this juncture, with the fixed and moving lenses abutted,
the optical train is precisely aligned. FIG. 7 schematically
illustrates an autofocus zoom camera module at this step of
assembly. The housing 701 has been deliberately drawn
asymmetrically with respect to the optical axis, 702 to illustrate
that it is the cup and cone registration features 703 that provide
the alignment between the fixed 704 and moving lenses 705 at this
juncture, not the housing and guide pins 706. Adhesive 707, or
another joining method may be applied and activated in certain
embodiments to attach the housing to the sleeves, or the leaf
springs, as appropriate. Because the guide pins are parallel to the
optical axis, the housing may now be displaced (801) along the
optical axis until the desired separation (802) between the fixed
and moving lenses is obtained, without significantly altering the
alignment between the fixed and moving lenses. The resulting
structure then appears as drawn in FIG. 8.
[0134] Lenses may be assembled in alternative embodiments into a
lens turret to form the optical train. In certain alternative
embodiments, the lens turret may be fabricated with an accurate
interior space, and the lenses of the movable group inserted and
fixed in the desired location inside the lens turret. In the
preceding discussion and drawings it has generally been presumed
that mechanical components of an autofocus camera, such as guide
pins, sleeves and a housing in certain embodiments, are symmetric
about the optical axis of the camera. In certain embodiments this
is desirable, while in others it is not.
[0135] An example of one or these embodiments is schematically
illustrated at FIG. 9. The optical axis of the camera 901 is
derived from the imager 902. The mechanical axis 903 is derived
from the guide pins 904 (four guide pins are drawn to illustrate
the central location). Because the camera module of this embodiment
includes an actuator 905, which takes space, the mechanical axis is
displaced 906 from the optical axis a distance that can range to
0.5 mm in some embodiments, or 0.2 mm in other embodiments, or 0.1
mm or smaller in further embodiments.
[0136] FIGS. 10A-10B illustrate differences between optics for a
fixed focus camera compared with an auto-focus camera. The fixed
focus camera of FIG. 10A has not moving lenses and instead includes
five fixed lenses L1-L5. FIG. 10B illustrates an example of an
auto-focus camera wherein five lenses L1-L5 are movable together to
adjust focus of an object at an arbitrary distance from the camera
module onto the image sensor. Using a voice coil motor or VCM
actuator, the five lenses L1-L5 are movable to adjust the focus. As
described above, a MEMS actuator is included in accordance with
several embodiments to move one or more movable lenses quickly and
without adding nearly as significantly to a Z height of the camera
module or thickness along the optical path or direction of motion
of the movable lens or movable lenses.
[0137] FIG. 10C illustrates an example of an optical train for an
autofocus zoom camera in accordance with embodiments. In the
example of FIG. 10C, lenses L1-L4 that are nearest an object end of
the optical path are movable to achieve autofocus functionality,
while L5 is fixed nearest to the image sensor. In fact, lens L5 has
a back focal length equal to its distance from the plane of the
image sensor. As described above, electronic zoom may be provided
by a combination of this fixed L5 lens and data processing. The
lens L5 is designed to compensate for a big field curvature. The
overall optical assembly may have fewer than five lenses or more
than five lenses. Moreover, the movable lens group may include
fewer than four lenses, and may include as few as one lens that may
be disposed at position L1, L2, L3 or L4 when L5 is designed to
provide zoom functionality.
[0138] FIG. 11 illustrates a section view of a camera module in
accordance with certain embodiments. In the example of FIG. 11,
L1-L4 are movable while L5 is fixed nearest the image sensor. The
movable lenses L1-L4 are disposed in a movable lens housing that is
coupled to a camera module body or image sensor component that is
itself coupled to a flexible printed circuit. The movable lens
housing utilizes a set of pairs of guide pins and sleeves to
facilitate the motion of the movable lenses L1-L4 as actuated by
the MEMS, piezo, VCM or other actuator (not shown in FIG. 11).
[0139] FIG. 12 illustrates a side view of the camera module of FIG.
11. A piezo motor is indicated in the example of FIG. 12 for moving
the movable lens housing the sleeves and guide pins. Alternatively,
a MEMS actuator may be used to move one, two, three or four movable
lenses to facilitate an autofocus feature or an autofocus zoom
feature of an advantageous camera module. The de-center and tilt
alignment of the movable lens group is advantageously precise as
described herein, while objects at arbitrary distances from the
camera module are automatically brought to focus by movement of the
movable lens or movable lenses of the autofocus camera module. An
ASIC or other electronic component is illustrated in FIG. 12 as
also being coupled to the flexible printed circuit along with the
camera module.
[0140] FIG. 13 illustrates the side view of the camera module of
FIG. 12 without the lenses L1-L5. In the example wherein a piezo is
used, a motor substrate is included as illustrated at FIGS.
12-13.
[0141] FIG. 14 illustrates a top view of the camera module of FIGS.
11-13. Two pairs of sleeves and guide pins are shown in this
embodiment to translate the movable lens housing containing the
movable lens group of the optical train of the camera module
relative to the image sensor and to the camera module housing and
to one or more fixed lenses in certain embodiments. The camera
module of FIG. 14 includes a piezo motor or MEMS for moving the
movable lens housing and/or one or more movable lenses of the
optical train whether or not the lens barrel also itself is
movable. In the embodiment wherein lenses L1 and L2 are fixed in a
first fixed lens group and lenses L4 and L5 are fixed in a second
fixed lens group and only lens L3 is movable to facilitate
autofocus, the movable lens housing may itself by fixed while the
MEMS component is coupled to the lens L3 and moves the lens L3 to
adjust the focus distance to objects disposed at arbitrary
distances to the camera module. A position sensor may be included
for monitoring, tracking, sensing and/or determining a position of
the movable lens housing or of the one or more movable lenses of
the optical train. An orientation sensor may also be included in
the form of an accelerometer or by utilizing capacitance values for
MEMS positioning components as described in more detail
separately.
[0142] FIGS. 15-18 illustrate advantageous examples involving zoom
factors for camera modules in accordance with embodiments. In
certain embodiments, optical zoom (OZ) may be used to create zoom
using a distorted lens and excess amount of pixels in the sensor.
The optical zoom factor may be calculated a product of lens
distortion zoom and extra pixels zoom and a digital component. In
one example wherein a five megapixel or 5 MP output is provided,
then for a sensor having excess pixels up to 8 MP, a zoom factor of
1.265 is achieved by the extra pixels. For excess pixels up to 10,
12 or 14 MP, zoom factors of 1.414, 1.550 and 1.673 are
respectively achieved.
[0143] A zoom factor provided by an optical zoom lens depends on
the allowed total track length (TTL) of the lens. For example, for
a large TTL (e.g., around 7 mm), a zoom factor of 1.42 is achieved
at center field, while for a smaller TTL (e.g., around 5.7 mm), a
zoom factor of 1.32 is achieved at center field in certain
embodiments. Continuing with these examples, if a 5 MP output is
provided, and a 12 MP input sensor is available, then for low TTL,
an overall zoom factor obtained by the optical zoom system at
center field is about .times.2. For a larger lens and TTL of 7 mm,
e.g., the optical zoom factor is about .times.2.2. FIGS. 17-18
respectively illustrate zoom factors for a 12 MP input sensor and
an 8 MP input sensor.
[0144] While example drawings and specific embodiments of the
present invention have been described and illustrated, it is to be
understood that that the scope of the present invention is not to
be limited to the particular embodiments discussed. Thus, the
embodiments shall be regarded as illustrative rather than
restrictive, and it should be understood that variations may be
made in those embodiments by workers skilled in the arts without
departing from the scope of the present invention. For example,
camera modules in accordance with various embodiments and component
of camera modules are described at U.S. patent application Ser.
Nos. 13/732,276, 13/571,393, 13/571,395, 13/571,397, 13/571,405,
13/445,857, 61/643,331, 61/657,012, 61/675,812, 61/698,567,
61/748,054, 61/748,062, 61/622,480.
[0145] In addition, in methods that may be performed according to
preferred embodiments herein and that may have been described
above, the operations have been described in selected typographical
sequences. However, the sequences have been selected and so ordered
for typographical convenience and are not intended to imply any
particular order for performing the operations, except for those
where a particular order may be expressly set forth or where those
of ordinary skill in the art may deem a particular order to be
necessary.
[0146] In addition, all references cited herein are incorporated by
reference, as well as the background, abstract and brief
description of the drawings, and U.S. application Ser. Nos.
12/213,472, 12/225,591, 12/289,339, 12/774,486, 13/026,936,
13/026,937, 13/036,938, 13/027,175, 13/027,203, 13/027,219,
13/051,233, 13/163,648, 13/264,251, and PCT application
WO2007/110097, and U.S. Pat. Nos. 6,873,358, and RE42,898 are each
incorporated by reference into the detailed description of the
embodiments as disclosing alternative embodiments.
[0147] The following are also incorporated by reference as
disclosing alternative embodiments:
[0148] U.S. Pat. Nos. 8,331,715, 8,279,301, 8,270,674, 8,224,108,
8,184,967, 8,055,090, 8,055,029, 7,855,737, 7,995,804, 7,970,182,
7,916,897, 8,081,254, 7,620,218, 7,995,855, 7,551,800, 7,515,740,
7,460,695, 7,965,875, 7,403,643, 7,916,971, 7,853,043, 7,773,118,
8,055,067, 7,844,076, 7,315,631, 7,792,335, 7,680,342, 7,692,696,
7,599,577, 7,606,417, 7,747,596, 7,506,057, 7,685,341, 7,694,048,
7,715,597, 7,565,030, 7,636,486, 7,639,888, 7,634,109, 7,536,036,
7,738,015, 7,590,305, 7,362,368, 7,352,394, 7,564,994, 7,315,658,
7,630,006, 7,440,593, 7,317,815;
[0149] U.S. patent application Ser. Nos. 13/306,568, 13/282,458,
13/234,149, 13/234,146, 13/234,139, 13/220,612, 13/084,340,
13/078,971, 13/077,936, 13/077,891, 13/035,907, 13/028,203,
13/020,805, 12/959,320, 12/944,701, and 12/944,662;
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