Optical: systems and elements – Deflection using a moving element
Reexamination Certificate
2000-03-27
2001-10-16
Phan, James (Department: 2872)
Optical: systems and elements
Deflection using a moving element
C358S487000, C358S497000
Reexamination Certificate
active
06304358
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical scanner for retrieving digital images of opaque and transmissive objects. In particular, this invention relates to a scanner in which the alignment of a transmissive mode light source and an image-retrieving device can be synchronously maintained.
2. Description of the Related Art
Recent developments in the use of high speed, low cost digital electronic imaging systems to process, transmit and display digital information have substantially increased the demand for optical scanners to convert information into digital electronic form. A variety of optical scanners, including facsimile machines and digital copiers, have been developed to meet this growing demand. The optical scanners generally fall within two categories: reflective scanners for scanning opaque objects, such as documents and photographs; and transmissive scanners for scanning transparent objects, such as slides and transparencies. Reflective scanners project light onto the side of the object to be scanned. The object illuminated by the reflected light is then viewed by a digital image-retrieving device that converts the image into a digital electronic form. Transmissive scanners project light through the object to be scanned. The transmissive object is also viewed by a digital image-retrieving device to then be stored in a digital electronic form. The growing demand for both reflective and transmissive scanners has resulted in a need for scanners to provide both capabilities.
AA conventional dual mode scanner is illustrated in FIG.
2
. This type of scanner includes a digital image-retrieving device
20
and a reflective mode light source
18
mounted on rails and driven by a motor
14
and belt
16
within the scanner body to scan along the length of the document. The reflective mode light source
18
projects light upon the portion of the object within the field of view of the image-retrieving device. Documents and photographs are placed on a transparent plate
22
. The reflective mode light source
18
and image-retrieving device
20
move incrementally lengthwise across a document placed on the transparent plate
22
to scan an image line by line.
This conventional dual mode scanner has a second light source
28
for scanning transmissive objects. This transmissive mode light source
28
is preferably housed behind a second transparent plate (not shown) within a scanner lid that overlies the scanner body. The transmissive mode light source
28
is movably mounted on a pair of rails and wired electronically to the scanner body to provide light through a portion of a transmissive object within the field of view of the image-retrieving device. The transmissive mode light source mechanism includes a second motor
24
and belt
26
to maintain the light directly within the image-retrieving device's field of view by incrementally moving along the rails in the scanner lid in synchronous movement with the image-retrieving device
20
.
In order to obtain the best picture quality, the transmissive mode light source
28
located in the scanner lid must be maintained in synchronous alignment with the image-retrieving device
20
located in the scanner body at all times during scanning. Referring to
FIGS. 1
a
and
1
b
, if transmissive mode light source
28
does not move synchronously with the image-retrieving device
20
, the relative positions of the transmissive mode light source
28
and the image-retrieving device
20
will not be maintained. Thus, the light intensity detected by image-retrieving device
20
will change, leading to a deterioration of the scanning quality.
The conventional dual mode (transmissive mode/reflective mode) scanner relies on the operation of two motors
14
,
24
and two belts
16
,
26
. Therefore, in addition to the extra cost of the second motor and belt, any aberration in the functioning of either motor or a slippage of either belt could lead to non-synchronous movement of the transmissive mode light source
28
and image-retrieving device
20
. Furthermore, such a scanner typically requires electronic circuitry in both the scanner body and the scanner lid to maintain the alignment between the transmissive mode light source
28
and the image-retrieving device
20
. This further increases the cost of manufacturing the scanner.
SUMMARY OF THE INVENTION
Accordingly, to overcome the drawbacks of the conventional scanner, the object of the present invention is to provide an optical scanner capable of scanning both opaque and transmissive objects in which the alignment of the transmissive mode light source and the image-retrieving device can be synchronously maintained.
To attain the above object, the present invention provides a physical engagement between the transmissive mode light source and the image-retrieving device; thereby, only one driving device is needed to move the transmissive mode light source, the reflective mode light source, and the image-retrieving device. More particularly, the present invention provides an optical scanner for retrieving digital images of both opaque and transmissive objects, comprising: a lower housing defining a longitudinal axis and having a slot formed there through; a first transparent plate disposed in the upper surface of the lower housing on which an object to be scanned is placed; an upper housing pivotally disposed on the lower housing so that the upper housing can be pivoted between an open and a closed position; a second transparent plate disposed in the lower surface of the upper housing, a second slot being formed through the second transparent plate, wherein the first slot and the second slot correspond in position; a first support frame disposed within the lower housing to be movable along the longitudinal axis; a first light source disposed on the first support frame for providing light to scan an opaque object; an image-retrieving device disposed on the first support frame; a second support frame disposed within the upper housing to be movable along the longitudinal axis; a second light source disposed on the second support frame for providing light to scan a transmissive object; means for engaging the first support frame to the second support frame through the first and second slots when the upper housing is in a closed position; and a driving device for synchronously moving the first support frame and the second support frame along the longitudinal axis.
By providing a physical engagement between the transmissive mode light source and the image-retrieving device, the alignment of the transmissive mode light source and the imaging-sensing device can be assured. Therefore, deterioration of the scanning quality due to misalignment of the transmissive mode light source and the image-retrieving device can be avoided. Since only a single driving device is needed to move the transmissive mode light source, the reflective mode light source, and the image-retrieving device, errors caused by any aberrations in the functioning of driving device can be limited. Furthermore, the extra cost of a second driving device and electronic circuitry necessary to synchronize two driving devices can be saved.
REFERENCES:
patent: 5966221 (1999-10-01), Tellam et al.
patent: 6233065 (2001-05-01), Lee
Ho Yi-Yi
Lin Chih-Hung
Acer Peripherals Inc.
Ladas & Parry
Phan James
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