Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
2000-08-02
2002-03-05
Grant, II, Jerome (Department: 2624)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C382S286000
Reexamination Certificate
active
06353486
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to an image scanner, and more particularly to an image scanner which includes means for correcting the scanning results so as to have a better scanning quality. The present invention is also related to a method for improving scanning quality of an image scanner.
BACKGROUND OF THE INVENTION
Nowadays, an image scanner has gradually become a standard peripheral equipment of a personal computer. Therefore, scanner manufacturers have been trying their best to improve the scanning quality, for example, to compensate brightness, chrominance, etc., and/or correct scanning line errors. On the other hand, high scanning speed is also a criterion of an exquisite image scanner.
In order to enhance the scanning speed of an image scanner, several devices and methods have been proposed in prior art. For example, please refer to
FIG. 1
which schematically shows home-sensor means for speeding up the movement of an image pickup module
11
from a standby line N to a scan start line M, i.e. a document reference line. In this case, it is assumed that the image pickup module
11
reaches the scan start line M after moving a distance D from the standby line N along the arrow direction. In other words, the image pickup module
11
directly moves a pre-determined distance, rather than moves pixel by pixel to detect the presence of a document, and then starts scanning. Therefore, the movement of the image pickup module
11
from the standby line N to the scan start line M is fast.
However, there are likely to be defects resulting from errors of various parts and/or assembling inaccuracy in this home sensor means. For example, if the image pickup module
11
is inaccurately installed at a position lower than a predetermined one while assembling, i.e. the standby line is lowered, the actual scan start line M
1
will be accordingly lower than the document reference line M after the same distance D of movement, referring to the dotted lines and the dotted arrow in FIG.
1
. Therefore, the top portion
13
of the document
12
will be missed out in the scanning operation.
On the other hand, when the image pickup module
11
reaches the scan start line M, the nth pixel unit of a CCD of the image pickup module
11
generally serves as the start point of the same scanning line, and the nth pixel unit and the pixel units thereafter are used to simultaneously pick up the image of the document line by line. If the image pickup module
11
slightly deflects from its pre-determined path owing to an assembling defect, the same distance D of movement will make the image pickup module
11
reach another line M
2
rather than the pre-determined scan start line M, referring to the dotted line and the dotted arrow of
FIG. 2
, so that the nth pixel unit of the CCD will be a little shifted, and the scanning of a left portion
14
of the document might be missed out. In addition, the scanning lines will slant.
Another conventional means is proposed to avoid the missing of document data. Please refer to
FIG. 3
which schematically shows means for precisely determining a scan start point in an image scanner. On the scanning platform of this image scanner, a black region
21
is provided in front of a scan start line R where a front edge of a document
22
to be scanned is positioned. In this case, the image pickup module (not shown) quickly moves toward the black region
21
, and then slowly passes through the black region
21
after reaches the black region
21
to detect the disappearance of the black color. When the detected black color disappears, the image pickup module keeps on moving and begins to measure a distance Q along the arrow direction. It is assumed that the scan start line R is reached after the image pickup module moves the distance Q from the reference point P. By this way, the downshift error resulting from the downshift installation of the image pickup module, as shown in
FIG. 1
, can be avoided because the predetermined distance Q is measured from the lower edge of the black region, i.e. the reference point P, rather than from the standby line of the image pickup module. Nevertheless, the defect of the conventional scanner indicated in
FIG. 3
still exists in this means, and is not resolved.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide an image scanner, which can use single means to simultaneously adjust various scanning results to improve scanning quality.
Another object of the present invention is to provide a method for improving scanning quality of an image scanner by easily and conveniently performing color calibration, and detection and correction of a deflection rate and/or an amplification error.
A first aspect of the present invention is directed to an image scanner. The image scanner includes a scanning platform for placing thereon an object to be scanned, which is marked thereon a document line for positioning a front edge of the object, a first color block located in front of the document line along a specific direction, and a second color block located in front of the document line along the specific direction and having an interface with the first color block; and the image scanner also includes a photo-signal processing device passing by the scanning platform from a home position along the specific direction, and performing a scanning operation from a scan start point behind the first and the second color blocks to read image data of the object, and converting the image data of the object into digital data for further processing. According to this aspect of the present invention, the interface of the first and the second color blocks includes a first reference point and a second reference point whose coordinates are detected according to color changes therearound, a shift from the first reference point to the scan start point is of a predetermined vector which can be used together with the coordinate of the first reference point for determining a position of the scan start point, and a distance between the first and the second reference points is of a constant value which can be used together with the coordinates of the first and the second reference points for determining a deflection rate of a scan track and an amplification error of a scan result.
In addition to the purposes of accurate scan start point, deflection correction and amplification adjustment, the first and the second color blocks can also be provided for color calibrations of the scan result. For example, if the two color blocks are formed of regions of standard white and standard black, respectively, calibrations of a light and a dark responses can be performed.
In a preferred embodiment, the first color block is enclosed within the second color block, and the first and the second color blocks are formed of regions of standard white and standard black, respectively, so that the. photo-signal processing device sequentially passes by the standard black region, the standard white region and the standard black region to perform color calibrations and error detection before the scanning operation starts. Alternatively, the first color block can be a standard black region and the second color block can be a standard white region so that the sequence the photo-signal processing device passes by is first the standard white region, next the standard black region and then the standard white region, and the same purposes can be achieved.
It is to be noted that the first constant value should be set adequately so as to maximize the overall scan speed while avoiding the scanning operation starting after the photo-signal processing device passes by the document line. In other words, it is preferred that the distance between the scan start point and the document line is no less than the first constant value.
A second aspect of the present invention is directed to another image scanner. The image scanner includes a scanning platform for placing thereon an object to be scanned, which is marked thereon a document line for positioning a fro
Grant II Jerome
Mustek Systems Inc.
Worku Negussie
LandOfFree
Device for improving scanning quality of 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 Device for improving scanning quality of image scanner, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for improving scanning quality of image scanner will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2831724