U.S. patent application number 09/730023 was filed with the patent office on 2001-04-05 for integrated optical imaging assembly.
Invention is credited to Berg, Thomas E., Miksch, Eugene A..
Application Number | 20010000110 09/730023 |
Document ID | / |
Family ID | 23085583 |
Filed Date | 2001-04-05 |
United States Patent
Application |
20010000110 |
Kind Code |
A1 |
Miksch, Eugene A. ; et
al. |
April 5, 2001 |
Integrated optical imaging assembly
Abstract
An integrated optical imaging assembly for scanning an object
may comprise a printed circuit board having an upper end and a
lower end. An optical detector is mounted to the upper end of the
printed circuit board at an end of an image light path, and a lens
system is mounted to the printed circuit board below the optical
detector to be interposed in the image light path. A reflector is
mounted to the lens in the image light path between the lens and
the optical detector to direct the image light path between the
lens and the optical detector. An illumination source is mounted to
the lower end of the circuit board to illuminate a second end of
the image light path below the lens, and an illumination reflector
is mounted to the lens opposite the illumination source to direct
an illumination light path from the illumination source toward the
image light path below the lens.
Inventors: |
Miksch, Eugene A.;
(Loveland, CO) ; Berg, Thomas E.; (Fort Collins,
CO) |
Correspondence
Address: |
HEWLETT-PACKARD COMPANY
Intellectual Property Administration
P. O. Box 272400
Fort Collins
CO
80527-2400
US
|
Family ID: |
23085583 |
Appl. No.: |
09/730023 |
Filed: |
December 4, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09730023 |
Dec 4, 2000 |
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09283342 |
Mar 31, 1999 |
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6160250 |
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Current U.S.
Class: |
250/208.1 ;
235/462.45; 235/472.01; 358/473; 382/313 |
Current CPC
Class: |
H04N 1/0311 20130101;
H04N 1/0312 20130101; H04N 1/0314 20130101 |
Class at
Publication: |
250/208.1 ;
235/472.01; 235/462.45; 358/473; 382/313 |
International
Class: |
H01L 027/00; G06K
009/22; G06K 007/10; H04N 001/024 |
Claims
What is claimed is:
1. A method of producing an imaging system comprising: connecting
an optical detector to a mounting surface; connecting an
illumination source to said mounting surface; and mounting an
imaging lens on said mounting surface between said optical detector
and said illumination source.
2. The method of claim 1, wherein said optical detector is
connected to said mounting surface at an end of a light path, said
illumination source is connected to said mounting surface at an
opposite end of said light path, and said imaging lens is connected
to said mounting surface to be interposed in said light path.
3. The method of claim 1, wherein connecting said optical detector
to said mounting surface comprises electrically connecting said
optical detector to a printed circuit board.
4. The method of claim 3, wherein electrically connecting said
optical detector to said printed circuit board comprises soldering
said optical detector to said printed circuit board.
5. The method of claim 1, wherein connecting said optical detector
to said mounting surface comprises connecting a contact image
sensor to said mounting surface.
6. The method of claim 1, wherein connecting said optical detector
to said mounting surface comprises connecting a plurality of
photodetectors to said mounting surface.
7. The method of claim 1, wherein connecting said illumination
source to said mounting surface comprises connecting a plurality of
light emitting diodes to said mounting surface.
8. The method of claim 1, wherein mounting said imaging lens on
said mounting surface comprises mounting a gradient index lens on
said mounting surface.
9. The method of claim 8, further comprising aligning said gradient
index lens before mounting it so that image light passing through
said gradient index lens falls on said optical detector.
10. The method of claim 1, wherein mounting said imaging lens on
said mounting surface comprises mounting at least one shaped
optical lens on said mounting surface.
11. The method of claim 10, wherein said at least one shaped
optical lens comprises at least one cylindrical lens.
12. The method of claim 1, wherein said mounting surface comprises
a flexible printed circuit, the method further comprising attaching
a mounting bracket to said flexible printed circuit to support said
flexible printed circuit.
13. The method of claim 2, further comprising mounting a reflector
to said mounting surface to change a direction of said image light
path between said imaging lens and said optical detector.
14. The method of claim 2, further comprising mounting a reflector
to said imaging lens to change a direction of said image light path
between said imaging lens and said optical detector.
15. The method of claim 2, further comprising mounting an
illumination reflector to said imaging lens to direct an
illumination light path from said illumination source onto said
light path.
16. The method of claim 2, further comprising mounting an
illumination reflector to said illumination source to direct an
illumination light path from said illumination source onto said
light path.
17. The method of claim 2, further comprising mounting a lens to
said mounting surface to direct an illumination light path from
said illumination source onto said light path.
18. The method of claim 1, further comprising mounting at least one
signal conditioning element to said mounting surface for
conditioning an electrical signal produced by said optical
detector.
19. A method of producing an optical imaging assembly, comprising:
providing a printed circuit board having an upper end and a lower
end; mounting an optical detector to said upper end of said printed
circuit board at an end of an image light path; mounting a lens to
said printed circuit board below said optical detector and
interposed in said image light path; mounting a reflector to said
lens in said image light path between said lens and said optical
detector for directing said image light path between said lens and
said optical detector; mounting an illumination source mounted to
said lower end of said printed circuit board for illuminating a
second end of said image light path below said lens; and mounting
an illumination reflector to said lens opposite said illumination
source for directing an illumination light path from said
illumination source toward said image light path below said lens.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
1. This application is a continuation of U.S. patent application
Ser. No. 09/283,342 which is hereby incorporated by reference for
all that is disclosed therein.
FIELD OF THE INVENTION
2. This invention relates to scanner devices in general and more
specifically to a scanner optical imaging assembly mounted on a
single circuit board.
BACKGROUND
3. Optical scanner devices are well-known in the art and produce
machine-readable image data signals that are representative of a
scanned object, such as a photograph or a page of printed text. In
a typical scanner application, the image data signals produced by
an optical scanner may be used by a personal computer to reproduce
an image of the scanned object on a suitable display device, such
as a CRT or a printer. Some examples of optical scanner devices are
fax machines, digital copiers, and computer scanners (flatbed and
portable).
4. Optical scanners are well-known in the art and various
components thereof are disclosed in U.S. Pat. No. 5,552,597 of
McConica for "Hand-Held Scanner having Adjustable Light Path", U.S.
Pat. No. 5,586,212 of McConica, et al., for "Optical Wave Guide for
Hand-Held Scanner," U.S. Pat. No. 5,381,020 of Kochis, et al., for
"Hand-Held Optical Scanner with Onboard Battery Recharging
Assembly," and U.S. Pat. No. 5,306,908 of McConica, et al., for
"Manually Operated Hand-Held Optical Scanner with Tactile Speed
Control Assembly," all of which are hereby incorporated by
reference for all that they disclose.
5. A typical optical scanner may include an optical imaging
assembly comprising illumination, optical, and detection systems.
The illumination source illuminates a portion of the object
(commonly referred to as a "scan region"), whereas the optical
system collects light reflected by the illuminated scan region and
focuses a small area of the illuminated scan region (commonly
referred to as a "scan line") onto the surface of a photosensitive
detector positioned within the scanner. The photosensitive detector
converts the image light incident thereon into electrical signals
representative of the scan line. Image data representative of the
entire object then may be obtained by sweeping the scan line across
the entire object.
6. The term "image light" as used herein refers to the light
reflected from the document and focused onto the surface of the
detector array by the optical system. The image light may be
converted into digital signals in essentially three steps. First,
the photosensitive optical detector converts the light it receives
into a varying electric current. Second, the varying electric
currents from the detector elements are converted into analog
voltages by an analog amplifier. Finally, the analog voltages are
digitized by an analog-to-digital (A/D) converter. The digital data
then may be processed and/or stored as desired.
7. While optical scanners of the type described above are being
used, they are not without their problems. Image quality, scanner
size and cost, and ease of assembly are related to the design and
complexity of the optical imaging assembly. For example, the
various components of the imaging assembly, i.e., the illumination
source, the optical system and the detection system, must be
precisely aligned to properly illuminate the document and focus the
image light onto the detectors. The position, orientation, and
distance of each element with respect to other elements must be
correct to within close tolerances. Furthermore, the imaging
assembly must be robust enough to resist shifting when the optical
scanner is jolted or the operating environment varies.
8. If the illumination source is not properly aligned, the scan
region may be too dark and the resulting image may lack contrast.
If the image light is not properly focused and directed onto the
detectors, the resulting image may be blurry or dark. Complex
mounting and alignment systems may be employed to address these
problems. However, a complex imaging assembly results in a
relatively large, costly, and error prone optical scanner.
Furthermore, the more complex the imaging assembly, the more
difficult it is to assemble, and the more likely elements are to
shift out of alignment.
9. Highly complex imaging assemblies also have a large tolerance
stack. It is impossible to manufacture each part to the exact
design measurements, therefore each part has a design tolerance, or
an acceptable amount of error in size or shape. As parts are
assembled together, the tolerance of each is added to a tolerance
stack. Therefore, when elements of the imaging assembly are
separated by a relatively large number of parts, the tolerance
stack between the parts is relatively large, and the alignment
error may be large enough to reduce image quality.
10. Consequently, a need exists for a smaller imaging assembly
which is simple to assemble and align, resulting in a lower cost. A
need further exists for an imaging assembly having a reduced
tolerance stack to improve alignment and simplify assembly or
repair.
SUMMARY
11. To assist in achieving the aforementioned needs, the inventors
have devised an integrated optical imaging assembly which greatly
simplifies assembly and alignment. This provides for smaller,
lighter, and less expensive scanners in general.
12. A method of producing an imaging system having features of the
present invention may comprise mounting an optical detector to a
mounting surface at a first end of an image light path. An optical
system is mounted to the mounting surface and interposed in the
image light path, and an illumination source is mounted to the
mounting surface to illuminate a second end of the image light
path.
13. The invention may also comprise a method of producing an
integrated optical imaging assembly which includes providing a
printed circuit board having an upper end and a lower end. An
optical detector is mounted to the upper end of the printed circuit
board at a first end of an image light path, and a lens system is
mounted to the printed circuit board below the optical detector to
be interposed in the image light path. A reflector is mounted to
the lens in the image light path between the lens and the optical
detector to direct the image light path between the lens and the
optical detector. An illumination source is mounted to the lower
end of the circuit board to illuminate a second end of the image
light path below the lens, and an illumination reflector is mounted
to the lens opposite the illumination source to direct an
illumination light path from the illumination source toward the
image light path below the lens.
BRIEF DESCRIPTION OF THE DRAWING
14. Illustrative and presently preferred embodiments of the
invention are shown in the accompanying drawing, in which:
15. FIG. 1 is a perspective view of a portable scanner device
having an integrated optical imaging assembly;
16. FIG. 2 is a front view of the portable scanner device shown in
FIG. 1;
17. FIG. 3 is a bottom view of the portable scanner device showing
the contact surface of the image head;
18. FIG. 4 is a perspective view of an integrated optical imaging
assembly;
19. FIG. 5 is a cross-sectional side view of the integrated optical
imaging assembly of FIG. 4 taken along line 48;
20. FIG. 6 is a front view of the integrated optical imaging
assembly of FIG. 4 with the mirror removed;
21. FIG. 7 is a cross-sectional side view of an integrated optical
imaging assembly having a metal image light reflector;
22. FIG. 8 is a cross-sectional side view of an integrated optical
imaging assembly having a lens to direct the illumination light
towards the scan region and having the image light reflector
mounted on the printed circuit board; and
23. FIG. 9 is a cross-sectional side view of an integrated optical
imaging assembly having a flexible printed circuit mounted on a
mounting bracket.
DESCRIPTION OF THE PREFERRED EMBODIMENT
24. An integrated optical imaging assembly 10 according to the
present invention may be used in a hand-held or portable image
scanner 12 to scan an object 14, such as a document 16 with written
text 18 provided thereon. For example, in the application
illustrated in FIG. 1, the entire document 16 may be scanned by
moving the portable image scanner 12 over the document 16 along a
meandering or curvilinear scanning path 20. As will be explained in
greater detail below, the integrated optical imaging assembly 10
associated with the portable image scanner 12 illuminates the
document 16, then directs and detects the reflected image light to
create a computer readable representation of the text 18 on the
document 16. The integrated optical imaging assembly 10
significantly simplifies the alignment of the imaging components
and reduces the required mounting hardware. The quality of the
image data produced by the optical detector 42 is thereby generally
improved. Assembly and repair of the scanner 12 is also simplified,
and size, weight, and cost is reduced.
25. Referring now to FIG. 2, one embodiment of the portable image
scanner 12 having an integrated optical imaging assembly 10 may
comprise a main housing portion 22 having an image head portion 24
associated therewith. The main housing portion 22 of the portable
image scanner 12 may be sized to receive the various electronic
components and other devices (not shown) required for the operation
of the portable image scanner 12. For example, in addition to
housing the various electronic components that may be required or
desired for the operation of the portable image scanner 12, the
main housing portion 22 may also be provided with a display device
26, along with various buttons or switches 28, 30, and 32 to
control the function and operation of the portable image scanner
12. The main housing portion 22 may also be sized to receive a
suitable power source, such as a battery (not shown), to provide
electrical power to the portable image scanner 12.
26. The image head portion 24 of portable image scanner 12 may be
configured to receive an integrated optical imaging assembly 10.
The face or contact surface 36 of the image head portion 24 may be
provided with an elongate aperture or slot 38 therein which allows
the integrated optical imaging assembly 10 to illuminate a scan
region 66 (FIG. 5) on the document 16. The aperture or slot 38 also
allows image light 62 reflected by the illuminated scan region 66
to be received by the integrated optical imaging assembly 10. The
integrated optical imaging assembly 10 produces an image signal
(not shown) based on the image light 62. Image data contained in
the image signal may then be processed or manipulated by an image
processing system (not shown) to produce image data that are
representative of the object 14.
27. As was briefly mentioned above, the integrated optical imaging
assembly 10 illustrated in FIGS. 4, 5, and 6 significantly aids
alignment and assembly by locating the imaging components on a
single mounting surface 40. The imaging components may be mounted
to the mounting surface 40 during one manufacturing process which
may be automated, avoiding manual assembly and alignment.
28. The integrated optical imaging assembly 10 also significantly
improves tolerance control by removing intermediate bodies such as
multiple mounting brackets from the tolerance stack.
29. The integrated optical imaging assembly 10 may comprise an
optical detector 42, an optical system 44, and an illumination
source 46, all attached to a mounting surface 40. The integrated
optical imaging assembly 10 of a preferred embodiment may also
comprise a mirror 84 and an illumination reflector 70 to direct the
image light 62 and illumination light 60. Signal conditioning
components 90, such as resistors and capacitors, may also be
mounted on the mounting surface 40. The illumination source 46
first illuminates a scan region 66 on the document 16. In a
preferred embodiment, the illumination source 46 directs the
illumination light 60 towards the illumination reflector 70, which
reflects the illumination light 60 down to the scan region 66 at an
angle. The illumination light 60 reflects off the document 16 as
reflected image light 62. The intensity of the image light 62
varies as a function of the text 18 or graphics (not shown) on the
document 16. Lighter areas on the document 16 reflect more intense
image light 62 than dark areas.
30. The image light 62 is reflected from a scan line region 64 on
the document 16 to the optical system 44 which focuses and directs
it. In a preferred embodiment, the image light 62 travels from the
optical system 44 to the mirror 84 which reflects it to the optical
detector 42. The optical detector 42 converts the image light 62
into electrical signals which are representative of the text 18 or
graphics on the document 16. The electrical signals may be further
conditioned or processed by signal conditioning components 90 also
mounted to the mounting surface 40.
31. In a preferred embodiment, the mounting surface 40 comprises a
printed circuit board, to which the imaging components (e.g., the
optical detector 42, optical system 44, and illumination source 46)
may be hand mounted using mounting jigs and fixtures, or
preferably, automatically mounted through the use of robotics
during the manufacturing process. The method of component
attachment may be solder, glue, clipping, heat staking, or any of a
number of conventional attachment methods known in the art. This
use of a unitary mounting surface greatly reduces the number of
parts required in the scanner 12 and the manual labor involved in
assembly and alignment, since the number of mounting and alignment
components is reduced.
32. The portable image scanner 12 having an integrated optical
imaging assembly 10 may be operated as follows to scan an object
14, such as document 16 with written text 18 thereon. As a first
step, the user (not shown) would set up or initialize the portable
image scanner 12 to perform the scanning operation by actuating the
appropriate buttons or switches (e.g., 28, 30, and 32) in
accordance with the particular operational sequence for the
specific scanner device. The user may then place the contact
surface or face 36 of the portable image scanner 12 against the
document 16 and initiate the scanning operation. The user then
moves the portable image scanner 12 across the document 16 as the
integrated optical imaging assembly 10 produces an electrical
representation of the document 16.
33. Having briefly described the integrated optical imaging
assembly 10 and its use in a portable image scanner 12, as well as
some of its more significant features and advantages, the various
embodiments of the integrated optical imaging assembly 10 will now
be described in detail. However, before proceeding with the
detailed description it should be noted that while the integrated
optical imaging assembly 10 is shown and described herein as it
could be used in a portable image scanner 12, it is not limited to
use with any particular type or style of scanner device. For
example, the integrated optical imaging assembly 10 could also be
used in a flatbed scanner or fax machine. It should also be noted
that while the portable image scanner 12 is shown and described
herein as it may be used to scan an object 14, such as a document
16 with written text 18 thereon, it is not limited to use with any
particular type of object 14. Indeed, the portable image scanner 12
may be used to scan almost any type of object imaginable.
Accordingly, the integrated optical imaging assembly 10 according
to the present invention should not be regarded as limited to the
particular type of portable scanner device and applications shown
and described herein.
34. With the foregoing considerations in mind, one embodiment of
the integrated optical imaging assembly 10 is shown and described
herein as it could be used in a portable or hand-held image scanner
12 which may be used to scan an object 14, such as a document 16
with written text 18 thereon. See FIG. 1. In order to scan the
entire document 16, it may be necessary for the user to move the
portable image scanner 12 along a curvilinear or meandering
scanning path 20. If so, the portable scanner device 12 may be
provided with a navigation system (not shown) to allow image data
(not shown) obtained along the meandering or curvilinear scanning
path 20 to be "stitched" together to provide image data
representative of the entirety of the scanned object 14. Exemplary
navigation systems and stitching algorithms are disclosed in U.S.
Pat. No. 5,089,712 of Holland for "Sheet Advancement Control System
Detecting Fiber Pattern of Sheet" and U.S. Pat. No. 5,578,813 of
Allen, et al., for "Freehand Image Scanning Device which
Compensates for Non-Linear Movement," both of which are
specifically incorporated herein by reference for all that they
disclose. However, since the details of the navigation system and
stitching algorithm that may be used in such a portable image
scanner 12 are not necessary to understand or practice the present
invention, the particular navigation system and stitching algorithm
that may be utilized a portable image scanner 12 will not be
described in further detail herein.
35. Referring now primarily to FIGS. 1-2, a portable image scanner
12 employing an integrated optical imaging assembly 10 may be
provided with a main housing portion 22 and an image head portion
24. The main housing portion 22 may comprise an overall
configuration or shape conducive to hand manipulation by a user
(not shown), although other configurations may also be used. In one
preferred embodiment, the main housing portion 22 may be sized to
receive the various electronic components (not shown) required for
the operation of the portable image scanner 12. Alternatively, some
or all of the various electronic components may be located
elsewhere and may be connected to the main housing portion 22 by a
suitable link, such as a cable (not shown). The main housing
portion 22 may also be provided with a display device 26 and
various switching devices 28, 30, and 32 that may be required or
desired for the operation of the portable image scanner 12. While
the switching devices 28, 30, and 32 in one preferred embodiment
are located on the front face of the main housing portion 22 of the
portable image scanner 12, they may be positioned at any convenient
location on the scanner 12. The electrical power required to
operate the portable image scanner 12 may be provided by a suitable
electrical power source, such as a battery (not shown), that may
also be contained within the main housing portion 22 of the
portable image scanner 12. However, since the various electronic
components, display devices, switching devices, and batteries that
may be required or desired for use in a particular portable image
scanner are well-known in the art and since descriptions of the
various components are not required to understand or practice the
present invention, the various components, e.g., electronic
components (not shown), display device 26, switching devices 28,
30, and 32, etc., utilized in one preferred embodiment of the
portable image scanner 12 will not be described in further detail
herein.
36. The main housing portion 22 of the portable image scanner 12
may be made from any of a wide range of materials, such as metals
or plastics, suitable for the intended application. By way of
example, in one preferred embodiment, the main housing portion 22
is made of polycarbonate plastic, although other materials could
also be used.
37. The image head portion 24 may be sized to receive an integrated
optical imaging assembly 10, as illustrated in FIGS. 4, 5, and 6.
In a preferred embodiment, the integrated optical imaging assembly
10 comprises an optical detector 42, an optical system 44, and an
illumination source 46 mounted on a mounting surface 40. The
mounting surface 40 may comprise a printed circuit board containing
the electrical wiring to connect the various elements of the
integrated optical imaging assembly 10. This also provides the
benefit of aiding in component alignment, since the electrical
traces and solder pads on a printed circuit board are precisely
positioned, providing a precise reference to position the
components on the board. Furthermore, the electrical components may
be mounted and soldered to the printed circuit board by automated
machinery, speeding assembly and lowering costs while correctly
aligning the components.
38. The optical detector 42 may comprise a contact image sensor
(CIS), an array of individual photodetectors, or an integrated
photodetector such as a charge-coupled device (CCD). A typical
individual photodetector changes electrical resistance in response
to exposure to light. As the intensity of the light reflected from
the image onto the photodetector changes, the electrical current
passing through the photodetector varies. Thus a photodetector may
be used to detect light and dark regions on an image. Similarly, a
charge-coupled device is a semiconductor device which builds up an
electrical charge in areas exposed to light. The varying electrical
charge distributed across the two-dimensional face of the
semiconductor thus contains an electrical representation of the
varying light intensity across the face. The light detection
surface of a CCD is smaller than the detection area of a document,
therefore a CCD generally requires a relatively elaborate optical
system to reduce and focus the image light onto the CCD. In
contrast, a CIS has substantially the same dimensions as the target
area to be detected on the document, so the image light only needs
to be directed from the document to the CIS without reduction.
39. In a preferred embodiment, the optical detector 42 comprises a
contact image sensor (CIS). Alternatively, other types of detectors
having the same or other resolutions could also be used. The
optical detector 42 is preferably connected to the printed circuit
board 40 with one or more wire-bonds 50, fine uninsulated
electrical wires which are soldered to the printed circuit board 40
by automated machinery.
40. An illumination source 46 is also mounted to the printed
circuit board 40 to illuminate a scan region 66 on a document 16
positioned under the integrated optical imaging assembly 10. The
illumination source 46 may comprise an array of light emitting
diodes (LED's) which may be positioned in spaced-apart relation on
the printed circuit board 40. The array of LED's in the
illumination source 46 may have a length that is substantially
coextensive with the integrated optical imaging assembly 10, which
is likewise substantially coextensive with the length of the scan
line 64 that is to be provided. In one preferred embodiment, the
integrated optical imaging assembly 10 may have a length 92 in the
range of about 120 mm to about 130 mm (123.2 mm preferred),
although other lengths could also be used. Each light emitting
diode in the illumination source 46 may comprise an LED part number
HSMA-S690, available from Hewlett-Packard Company of Palo Alto,
Calif. The number of light emitting diodes provided in the
illumination source 46 will depend on the length 92 of the
integrated optical imaging assembly 10 as well as on the desired
intensity of the illumination that is to be provided to the scan
region 66. By way of example, in one preferred embodiment, the
illumination source 46 may be provided with eighteen (18) separate
light emitting diodes. The light emitting diodes in the
illumination source 46 utilized in one preferred embodiment produce
a substantially uniform light output over a wide angle, nearly
180.degree. in some cases. The illumination source 46 illuminates a
scan region 66 on a document 16 positioned under the integrated
optical imaging assembly 10. The illumination source 46 preferably
illuminates the scan region 66 at multiple angles.
41. Alternatively, the illumination source 46 may comprise any of a
wide variety of light sources now known or that may be developed in
the future that are suitable for use with the integrated optical
imaging assembly 10. Illumination source selection must take into
account the type of optical detector 42, the document 16 type, the
power, light intensity, and light wavelength requirements, etc. For
example, an alternate illumination source 46 may comprise a
fluorescent lamp.
42. The illumination source 46 may be surface mounted or wire
bonded to the printed circuit board 40, or may be connected by any
other suitable means.
43. An optical system 44 may be used to direct and focus the image
light 62 toward the surface of the optical detector 42. The optical
system 44 may comprise any of a wide variety of imaging systems
suitable to direct and focus the image light 62, such as typical
lens systems or projection imaging systems involving lenses and/or
reflectors. For example, the optical system 44 may comprise a
microlens array mounted to the printed circuit board 40.
44. In a preferred embodiment, the optical system 44 comprises a
rod lens array, or gradient index lens. A gradient index (GRIN)
lens comprises an array of glass or plastic tubes mounted side by
side in a single housing. Each tube directs light by refraction due
to a refractive index which smoothly varies from the center of the
tube out to the edges. In a preferred embodiment, the optical
system 44 may comprise a GRIN lens such as the type sold under the
name SELFOC which is a registered trademark of the Nippon Sheet
Glass Company, Limited, having a height 56 of about 6.9 mm and a
width 58 of about 3.8 mm. The optical system 44 is mounted to the
printed circuit board 40 between the optical detector 42 and the
illumination source 46 at a distance 54 below the optical detector
42 between about 2.17 mm and about 2.27 mm (2.22 mm preferred). The
optical system 44 may be mounted to the printed circuit board 40
using an adhesive layer or by any other suitable means.
45. To aid in directing illumination light 60 and image light 62,
the integrated optical imaging assembly 10 may also comprise an
illumination reflector 70 and a mirror 84. For example, the optical
detector 42 has a detection field, or a field of view, which is
directed away from the printed circuit board 40 rather than down
toward the scan region 66 on the document 16 when the optical
detector 42 is mounted to the printed circuit board 40. The mirror
84 reflects the image light 62' emerging from the optical system 44
toward the detection field of the optical detector 42.
46. In a preferred embodiment, a reflector mount 76 is mounted to
the optical system 44 opposite the printed circuit board 40. The
illumination reflector 70 is attached to the lower end of the
reflector mount 76 opposite the illumination source 46, while the
mirror 84 is attached to the upper end of the reflector mount 76
opposite the optical detector 42. In a preferred embodiment, the
reflector mount 76, illumination reflector 70, and a mirror mount
82 and 86 are integrally formed of sheet metal having a thickness
72 of about 0.5 mm. The reflector mount 76 is bent to an angle 74
of about 135 degrees to form the illumination reflector 70, and to
an angle 52 of about 45 degrees to form the mirror mount 82 and
86.
47. The illumination reflector 70 preferably comprises a polished
surface of the sheet metal used to form the reflector mount 76,
illumination reflector 70, and mirror mount 82 and 88.
Alternatively, the illumination reflector 70 may comprise a mirror
(not shown) attached to the reflector mount 76.
48. Alternatively, the reflector mount 76 may be molded of plastic
with an illumination reflector 70 and a mirror mount 82 and 88,
with an illumination mirror (not shown) and an image light mirror
84 mounted thereon.
49. The image light mirror 84 in a preferred embodiment comprises a
front surface glass substrate mirror having a thickness 80 of about
1.9 mm. A front surface mirror may aid in the layout of the
integrated optical imaging assembly 10 and typically has a higher
reflectivity than a rear surface mirror, but may have a higher
cost. The mirror 84 may comprise either a front surface mirror or a
rear surface mirror, or any other suitably reflective surface,
according to the needs of the scanner designers.
50. The mirror 84 may be mounted to the mirror mount 82 and 88
portion of the reflector mount 76 by a thin adhesive layer or by
metal tabs on the reflector mount 76 bent around the edges of the
mirror 84. The mirror mount comprises a lower support surface 82
and an upper support surface 88, forming a cutout region 86 in the
reflector mount 76. The mirror 84 is mounted to the upper and lower
support surfaces 88 and 82 so that the image light 62' may pass
through the cutout 86 to reflect from the mirror 84. Alternatively,
the mirror 84 may be mounted to the reflector mount 76 in any
suitable fashion to maintain the correct position and angle 52.
51. The mirror 84 may add an additional benefit of reducing stray
light incident on the optical detector 42. By positioning the upper
support 88 of the reflector mount 76 and the mirror 84 as closely
as possible to the printed circuit board 40, stray light reflected
inside the image head 24 is prevented from reaching the optical
detector 42. The optical detector 42 may thereby be surrounded by
the printed circuit board 40, the optical system 44, and the mirror
84 in a substantially closed configuration. The quality of the
resulting scanned image produced by the integrated optical imaging
assembly 10 is dependent upon the quality and purity of the image
light 62 reaching the optical detector 42. Reducing stray light
incident on the optical detector 42 thus improves the overall image
quality.
52. Alternatively a prism (not shown) could be used in place of the
mirror 84 to fold the image light path 62', internally reflecting
the image light 62'. In another alternative embodiment, a
refractive element could be used to fold the image light path 62'
refractively.
53. During operation of the integrated optical imaging assembly 10,
the illumination source 46 produces illumination light 60 to
illuminate the scan region 66 on the document 16. The scan region
66 is illuminated by light rays traveling directly from the
illumination source 46 to the document 16 (e.g., 60") and by light
rays reflecting from the illumination reflector 70 (e.g., 60').
Image light 62 is reflected from the illuminated scan line 64
inside the scan region 66 on the document 16 and travels to the
optical system 44. Focused and directed image light 62' emerges
from the optical system 44 and is reflected by the mirror 84 toward
the optical detector 42. The image light traveling toward the
mirror 84 (e.g., 62 and 62') may be substantially parallel to the
mounting surface 40, while the image light 62" traveling from the
mirror 84 to the optical detector 42 may be substantially
perpendicular to the mounting surface 40. The optical detector 42
then converts the reflected image light 62" into electrical signals
representing the light and dark patterns on the scan line 64.
54. The integrated optical imaging assembly 10 may also comprise
signal conditioning components 90 mounted to the printed circuit
board 40 to condition the electrical signals from the optical
detector 42 and the electrical power provided to the illumination
source 46. The signal conditioning components 90 may comprise
electrical components such as resistors and capacitors, preferably
miniature surface mount components.
55. In an alternative embodiment, illustrated in FIG. 7, an
integrated optical imaging assembly 110 may include a mounting
surface 140 comprising a printed circuit board, with an optical
detector 142, an optical system 144, and an illumination source 146
mounted thereon. The optical detector 142 may comprise a CIS
mounted to the printed circuit board 140 with a plurality of wire
bonds 150. The optical system 144 may comprise a GRIN lens having a
height 156 of about 6.9 mm and a width 158 of about 3.8 mm. The
optical system 144 is mounted to the printed circuit board 140
between the optical detector 142 and the illumination source 146 at
a distance 154 below the optical detector 142 between about 2.17 mm
and about 2.27 mm (2.22 mm preferred). The illumination source 146
preferably comprises an array of 18 LED's mounted to the printed
circuit board 140 below the optical system 144.
56. A reflector mount 176 is mounted to the optical system 144
opposite the printed circuit board 140, having an illumination
reflector 170 and an image light reflector 184 connected thereto.
The reflector mount 176, the illumination reflector 170 and the
image light reflector 184 may be integrally formed of sheet metal
having a thickness 172 of about 0.5 mm. The angle 152 between the
reflector mount 176 and the image light reflector 184 may be about
45 degrees, and the angle 174 between the reflector mount 176 and
the illumination reflector 170 may be about 135 degrees. The bends
in the sheet metal 152 and 174 may be formed in a stamping
operation or other bending process.
57. The illumination reflector 170 and the image light reflector
184 may comprise polished surfaces on the sheet metal or any other
reflective surface such as a reflective coating or a glass
substrate mirror mounted to the reflector mount 176. The reflector
mount 176 may be mounted to the optical system 144 with a thin
adhesive layer or with any other suitable mounting means, such as
heat staking, clips, or screws. To heat stake the reflector mount
176 to the optical system 144, small plastic tabs (not shown) may
extend from the optical system 144 through corresponding holes in
the reflector mount 176, where they are melted to increase the
width of the plastic tabs, preventing them from withdrawing through
the holes in the reflector mount 176.
58. A plurality of signal conditioning components 190 may also be
mounted to the printed circuit board 140 to condition or process
the electrical signals to and from the illumination source 146 and
the optical detector 142.
59. During operation of the integrated optical imaging assembly
110, the illumination source 146 produces light rays (e.g., 160 and
160") to illuminate a scan region 166 on the document 116
positioned below the integrated optical imaging assembly 110. The
illumination source 146 may direct light rays through an angle of
up to 180 degrees, thus some light rays (e.g., 160") may reach the
scan region 166 directly, while other light rays (e.g., 160 and
160') are reflected from the illumination reflector 170 to the scan
region 166.
60. Image light 162 is reflected from a scan line 164 in the scan
region 166 on the document 116 to the optical system 144. The
optical system 144 focuses and directs the image light 162' up to
the image light reflector 184, and reflected image light 162"
travels from the image light reflector 184 to the optical detector
142. The optical detector 142 then produces electrical signals
representative of the scan line 164, and the electrical signals may
then be conditioned or processed by the signal conditioning
components 190.
61. In an alternative embodiment of an integrated optical imaging
assembly 210, illustrated in FIG. 8, an optical detector 242, an
optical system 244 and a illumination source 246 are mounted to a
mounting surface 240 as in other embodiments discussed previously.
The mounting surface 240 may comprise a printed circuit board or
other rigid substrate, with the optical system 244 preferably
connected by a plurality of wire bonds 250.
62. A mirror 284 may be mounted to the mounting surface 240 above
the optical system 244 to angle down over the optical detector 242.
An illumination lens 294 may be mounted below the illumination
source 246 to direct the illumination light 260 toward a scan
region 266 on a document 216 positioned below the integrated
optical imaging assembly 210. The illumination lens 294 is
preferably mounted to the mounting surface 240. Alternatively, the
illumination lens 294 may be mounted to the illumination source
246.
63. In another embodiment of an integrated optical imaging assembly
310 illustrated in FIG. 9, a flexible printed circuit 396 is
mounted to a rigid mounting bracket 397. The mounting bracket 397
comprises a top portion 399 and a side portion 398, with the
flexible printed circuit 396 bending to mount to both the top and
side portions 399 and 398.
64. An optical detector 342 is connected with a plurality of wire
bonds 350 to the portion of the flexible printed circuit 396 that
is mounted to the top portion 399 of the mounting bracket 397. The
top portion 399 of the mounting bracket 397 is substantially
parallel to a document 316 positioned below the integrated optical
imaging assembly 310. As a result, the detection field of the
optical detector 342 is directed toward the document 316 and the
image light 362' need not be reflected.
65. An optical system 344 is mounted to the flexible printed
circuit 396 on the portion of the flexible printed circuit 396 that
is mounted to the side portion 398 of the mounting bracket 397. The
optical system 344 is positioned so that an optical axis of the
optical system 344 is aligned below the optical detector 342
directly in the detection field of the optical detector 342.
66. An illumination source 346 is located between the optical
system 344 and the document 316, and is connected to the flexible
printed circuit 396 on the portion of the flexible printed circuit
396 that is mounted to the side portion 398 of the mounting bracket
397. An illumination lens 394 is mounted below the illumination
source 346. The illumination lens 394 is preferably mounted to the
flexible printed circuit 396. Alternatively, the illumination lens
394 may be mounted to the illumination source 346.
67. During operation of the integrated optical imaging assembly
310, the illumination source 346 produces illumination light 360
which is directed by the illumination lens 394 toward the document
316. Image light 362 is reflected from the document 316 toward the
optical system 344. The optical system 344 focuses and directs the
image light 362' onto the optical detector 342, which produces
electrical signals representative of the image light 362.
68. While illustrative and presently preferred embodiments of the
invention have been described in detail herein, it is to be
understood that the inventive concepts may be otherwise variously
embodied and employed, and that the appended claims are intended to
be construed to include such variations, except as limited by the
prior art.
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