Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
2001-09-19
2004-04-20
Lee, Cheukfan (Department: 2622)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S486000, C358S483000, C358S474000
Reexamination Certificate
active
06724505
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to an image scanning method used in a scanner. More specifically, the present invention discloses an image scanning method for increasing a resolution of a document image used in a scanner.
2. Description of the Prior Art
A scanner is a widespread peripheral device for scanning documents and producing corresponding image data. The scanner has some additional functions, such as faxing image data to a fax machine over telephone lines, transmitting the image data in e-mail format over a network, or connecting to a printer to print the image data.
Please refer to FIG.
1
and FIG.
2
.
FIG. 1
is a diagram of a scanner
10
according to the prior art.
FIG. 2
is a functional block diagram of the scanner
10
. The scanner
10
comprises a housing
12
, control circuitry
22
for controlling operations of the scanner
10
, a scanning module
18
installed inside the housing
12
, and a step motor
20
installed inside the housing
12
and electrically connected between the control circuitry
22
and the scanning module
18
. As shown in
FIG. 1
, a transparent platform
14
is set on the housing
12
for a document
16
to be placed on. While the scanning module
18
scans the document
16
, the control circuitry
22
controls the step motor
20
to drive the scanning module
18
step by step so as to scan the document
16
.
Please refer to
FIG. 3
, which is a diagram of a movement of the scanning module
18
when utilizing a prior art image scanning method. As shown in
FIG. 3
, when the document
16
is placed on the transparent platform
14
for performing a scanning pass, the scanning module
18
moves forward continuously along an X direction from a starting end
17
in a fixed space corresponding to one step of the step motor
20
, and performs actions of exposure and images reading until the scanning module
18
reaches a stopping end
19
of the scanner
10
. Then, the scanning module
18
moves backward to the starting end
17
from the stopping end
19
so as to complete a scanning procedure.
To double the resolution of the scanned image, the prior art scanner utilizes the control circuitry
22
to control the step motor
20
to move a step unit which is half the original step distance of the step motor
20
so as to scan the document
16
. In this way, pixel numbers of the scanned image of the document
16
are doubled. When the scanning module
18
completes the scanning procedure to scan the document
16
, the resolution of the document
16
image increases twofold.
Nevertheless, from a standpoint of motor control, when the scanner
10
doubles the resolution of the scanned image, the step motor
20
uses half-step control. Under half-step control, a scanning rate of the step motor
20
is slower, in contrast with full-step control, so that it is easy to cause missteps of the scanning module
18
, which leads the scanning procedure to produce errors if the scanner
10
uses the half-step control too much. Furthermore, in the backward process, after completing the scanning procedure, the scanning module
18
only does oblique auto-correcting, auto-reducing and bright contrast correction image processing, without taking image samples from the document
16
. In today's image processing field, a data-transmitting mode of the scanner
10
is increasingly fast, and a rate of image processing accelerates. Under these conditions, very little time is spent performing image processing during the backward process. It seems a waste of the rest of that time not to take image samples from the document
16
.
SUMMARY OF INVENTION
It is therefore a primary objective of this invention to provide an image scanning method for increasing resolution of a document image used in a scanner.
The present invention, briefly summarized, discloses an image scanning method used in a scanner. The scanner includes a housing, a transparent platform set on the housing for a document to be placed on, a scanning module installed inside the housing for scanning the document, and a step motor for driving the scanning module step by step so as to scan the document. After completing a first scanning pass, the scanning module moves a predetermined distance, which corresponds to non-integer steps of the step motor, so that when the scanning module performs a second scanning pass, sampling positions of the second scanning pass are different from sampling positions of the first scanning pass.
It is an advantage of the present invention that the image scanning method still utilizes full-step control of the step motor to perform a scanning procedure. The full-step control of the step motor allows the step motor to maintain a normal step rate so that time of the scanning procedure is reduced, and further avoids problems of motor missteps for increasing resolution of the document when performing the scanning procedure.
These and other objectives and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
REFERENCES:
patent: 4575769 (1986-03-01), Arnoldi
patent: 5359271 (1994-10-01), Husher
patent: 5373372 (1994-12-01), Loewen
patent: 5945800 (1999-08-01), Chen
patent: 6101006 (2000-08-01), Bryant et al.
patent: 6147780 (2000-11-01), Chiang
patent: 6278513 (2001-08-01), Murata et al.
patent: 6414461 (2002-07-01), Chang
patent: 6531690 (2003-03-01), Kozuka
patent: 6603581 (2003-08-01), Lam et al.
Avision Inc.
Hsu Winston
Lee Cheukfan
LandOfFree
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