Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1998-03-23
2004-10-05
Grant, II, Jerome (Department: 2626)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S483000, C358S497000, C358S494000
Reexamination Certificate
active
06801343
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to image scanners for providing document and picture information to computers, in particular to flat bad image scanners.
A flat bed image scanner is widely used today is a periphery equipment for scanning documents, books and pictures and for furnishing the scanned information to a computer to be processed. However, traditional flat bed image scanner leaves much to be desired in terms of cost and volume. In other words, it is desirable to develop a smaller and less costly flat bed image scanner.
FIG. 1
shows the structure of a conventional flat bad image scanner, which includes an image reading sensor
11
c
, a glass window
5
, a sliding guide
7
, a frame
12
, driving mechanism (not shown) and image processing circuit (not shown). The principle of operation is as follows:
A document or picture
13
is placed over a window
5
. The image
6
is irradiated with a light source
11
a
which is mounted on an optical carriage
11
. The reflected light L passes through a group of reflecting mirrors
111
,
112
,
113
and lens
11
b
, and impinges on an image sensor
11
c
. Signals sensed by the sensor
11
c
are processed by electronic circuits (not shown) to be digitized. After the sensor
11
c
completes scanning the signals from one row or one area, a translating mechanism (not shown) moves the carriage
11
along the guide
7
to a next scanning position. The carriage
11
is held in place by a flange
11
d
which wraps around the guide
7
. This scanning continues until complete image information is read.
The biggest drawback of such a carriage
11
containing the light source
11
a
, the reflecting mirrors
111
,
112
,
113
, the sensors
11
c
and the flange
11
d
, lies in its bulkiness and the long light path between the image appearing at position
6
and the reflected image appearing at the sensor
11
c
. Take a standard size A4 paper, the distance between position
6
and the sensor
11
c
is more than 26 cm. In a conventional “flat bed image scanner” with three reflecting mirrors, the optical carriage has a cross-sectional area of approximately 9 cm×6 cm.
It is desirable to reduce the size, the power consumption and the cost of a flat bed image scanner. One approach to overcome the problem is to forego the mirror and lens system as the basic element and use a “Contact Image Sensor” CIS to construct a flat bed image scanner. The flat bed image scanner can achieve small size. The contact image sensor used in the present invention as shown in
FIG. 2
measures only 2 cm×2 cm approximately, containing a light source
1
a
, a focusing lens
1
b
, an image sensor
1
c
, a dust shielding window
1
d
, and a frame
1
e
. Position
6
a
is where an object is scanned. However, the contact image sensor has a drawback in that the depth of focus is very short, only 0.3 mm in depth. In other words, if position
6
a
is off by 0.3 mm upwards or downwards, the image becomes fuzzy. On the other hand, the traditional optical system
11
shown in
FIG. 1
has a depth of focus as deep as 5 mm.
Thus, it is necessary to overcome the problem of shallow depth of focus for a flat bed image scanner. The traditional optical system shown in
FIG. 1
cannot be used directly for a contact image sensor, because when a contact image sensor rides on a track to travel, it is difficult to maintain an error of less than 0.3 mm between the object and the contact image sensor. Any fluctuation in mechanical dimension or change in temperature can cause deformation in material and renders mass production difficult.
SUMMARY
An object of this invention is to devise a structure adapted to the shallow depth of focus of a contact image sensor for use in a flat bed image scanner. Another object of this invention is to reduce the optical path in a flat bed image scanner. Still another object of this invention is to reduce the cross-sectional area of a flat bed image scanner.
These objects are achieved in this invention by using a novel structure for the contact image sensor. The contact image sensor is pressed against the glass window by a spring, so that the sensor can slide in intimate contact with the glass window. Thus, the distance between the scanned object and the contact image sensor can be held within an error 0.3 mm. Any error in mechanical precision or due to temperature fluctuation cannot adversely affect the scanning quality of the image scanner.
REFERENCES:
patent: 5012354 (1991-04-01), Tsuchiya
patent: 5046159 (1991-09-01), Hamanaka
patent: 5163117 (1992-11-01), Imanishi et al.
patent: 5734483 (1998-03-01), Itoh
patent: 5764382 (1998-06-01), Shiraishi
patent: 5801851 (1998-09-01), Sheng
Avision Inc.
Grant II Jerome
Lin Patent Agent H. C.
LandOfFree
Flat bed image scanner does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flat bed image scanner, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flat bed image scanner will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3281718