Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2000-04-03
2002-07-30
Kim, Robert H. (Department: 2882)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S208100
Reexamination Certificate
active
06426498
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to optical scanner devices and, more particularly to a cost effective and functionally efficient optics module and scan window for an optical scanner device.
2. Description of the Related Art
Optical scanners are well-known in the art to produce machine-readable data that can represent an image contained on an object, e.g. a page of printed text. In general, the data is obtained from an optics module reflecting a beam of light off of a “scan line” region of the object being scanned. When an optics module is used in a portable scanner, the reflected beam of light is obtained as the user physically moves the optical scanner across the object with their hand. Consequently, the optics module for hand-held or portable scanning devices must generally be very compact and often employ a navigational assembly to track and associate what portion of the object has been scanned.
Referring to
FIG. 1
, the basic components of a portable scanner are shown. The scanner
5
includes an optics module
10
having a scanning assembly
12
and a navigational assembly
14
coupled to an image processing system
30
. With each assembly, an illumination device
16
, such as one or more LED's, creates a beam of light
18
A,
18
B that passes through the scanner casing
20
at a scan window
22
A,
22
B having a transparent material
32
. Next, the beam of light
18
A,
18
B reflects off of the surface of the object
24
being scanned before reflecting back through the scan window
22
A,
22
B. The reflected beam of light
18
A′,
18
B′ is focused by a lens
26
and received by an illumination sensor or photosensor
28
.
The photosensor
28
works with other electronic components
30
to evaluate and translate the reflected beam of light
18
A′,
18
B′ into an electronic copy of the image contained by the object
24
. The electronic components
30
could include a microprocessor, memory and related translational software that is contained by the scanner or by a personal computer being accessable by a data cable.
With the conventional optics modules described above, the illumination source
16
radiates light over a full hemisphere, so only a small portion of the light is directed toward the scan region, and the light flux per unit angle is relatively low. Consequently, if the illumination source
16
is tilted or moved slightly away from the object
24
, the illumination level through the scan window
22
A and
22
B at the scan line falls rapidly, resulting in an undesirably dark image or a very non-uniform image to be captured by the photosensor
28
.
The transparent material
32
is made from plastic or glass and functions as a seal in the casing so that the optical and electronic components contained therein can be protected from dust, moisture and other potential contaminants that could possibly damage the operation of the scanner. The transparent material provides optical losses due to surface reflections and internal transmissions. In particular, each time a beam of light
18
A or
18
A′ passes through the transparent material, the beam of light is diminished by about 8%. An anti-reflective coating may be applied to the transparent material to reduce the optical losses, however this will only reduce the optical loss to about 1.5%.
FIG. 2
illustrates a cross-sectional view of how the transparent material
32
may be secured to the scanner casing
20
. In particular,
FIG. 2
shows how the casing
20
can be manufactured to provide a scan window
22
A,
22
B that includes a ledge for supporting the transparent material
32
with an adhesive
36
. With this structure, the transparent material
32
is positioned a depth “d”, between 0.02-0.05 mm, away from an outer surface
38
of the casing
20
to create a recessed border defined by square comer regions
40
.
The recessed border is not deep enough to prevent a staple or a hard particle contained on an object from scratching the transparent material while the object is being scanned. In addition, the square comer regions
40
collect dust and other contaminants in areas that are hard to clean. Consequently, the scratches and collected contaminants further increase optical losses in the operational scanner. In turn, such optical losses may force the user to have the manufacturer replace the transparent material, which is not only time consuming, but costly. Lastly, the square comer regions
40
may cause the comers of the object being scanned to become jammed along the recessed borders of the scan window during the scanning process.
Thus, it would be desirable to provide an apparatus that overcomes the above problems associated with an optics module and scan window for a scanning devices.
SUMMARY OF THE INVENTION
In one embodiment, the present invention provides an optical scanner having a casing. The casing includes a scan window, a substrate attached within the casing and being laterally spaced from the scan window, and an optics module coupled between the scan window and the substrate to form a recess within the casing.
In another embodiment, the present invention provides a method for manufacturing a recessed scan window for use in an optical scanning apparatus having a casing. The method includes: forming a contact window within a scan surface of the apparatus casing; securing a substrate within the apparatus casing; coupling a first end of an illumination device to the substrate and a second end adjacent to a first portion of the contact window; and coupling a first end of a photosensor component to the substrate and a second end adjacent to a second portion of the contact window, wherein the second end of the illumination device and the photosensor component forms the recessed scan window.
REFERENCES:
patent: 5272518 (1993-12-01), Vincent
patent: 5306908 (1994-04-01), McConica et al.
patent: 5381020 (1995-01-01), Kochis et al.
patent: 5644139 (1997-07-01), Allen et al.
patent: 5936238 (1999-08-01), Bohn
patent: 6002124 (1999-12-01), Bohn et al.
Bohn David D.
Miksch Eugene A.
Hewlett-Packard Co.
Kim Robert H.
Mason David M.
Thomas Courtney
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