Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Reexamination Certificate
1995-03-22
2001-10-09
Grant, II, Jerome (Department: 2624)
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
C358S465000, C358S521000
Reexamination Certificate
active
06301019
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to image reading apparatuses, methods of reading images, whiteness level correcting methods and whiteness level generating methods, and more particularly to an image reading apparatus and an image reading method for reading an image on an original, and to a whiteness level correcting method and a whiteness level generating method employed in reading an image on an original.
Recently, with less paper being used in offices, image inputting products (image scanners) have been used as inputting means for storing documents in optical disks or the like. As the volume of images increases, high-speed input systems are used more often. Hence, use of automatic paper feeding is being practiced more and more widely.
In the case where automatic paper feeding is used in image reading, a CCD (charge coupled device) starts a reading operation at a member (hereinafter, referred to as a backing part or a backing member) for supporting the backside of an original so that the leading edge of the original can be read.
Since a reading is started at the backing part, a ground color (reference color) of the original cannot be read properly. In some cases, an image reading apparatus may produce a darkened output. Another problem in a conventional image reading apparatus is that, when a large volume of input originals are processed, the backing part and the input original may undergo friction, resulting in a flaw extending in a longitudinal direction being created in he backing part. When the flaw is created, the output f the image reading apparatus often accompanies a white or black streak.
Thus, an arrangement, whereby it is ensured that the leading edge of an automatically fed original is read, is met by a difficulty in obtaining a high-quality image which is true to the original.
For this reason, there is required an image reading apparatus capable of producing a high-quality image true to the original that is fed automatically.
2. Prior Art
FIG. 1
shows a construction of a conventional image reading apparatus
91
. The image reading apparatus
91
has an electrooptical converter
92
for reading an image optically, an image processing unit
93
for processing a signal obtained in the electrooptical converter
92
, a feeding mechanism as for transporting an original
94
, a carriage driving mechanism
96
for moving the electrooptical converter
92
, and a controller
97
for controlling the image processing unit
93
, the feeding mechanism
95
and the carriage driving mechanism
96
.
The image reading apparatus
91
includes: a flat-bet (FB) function whereby the electrooptical converter
92
is moved by the carriage driving mechanism
96
to scan an original
94
so that the image thereon is read; and an automatic document feeder (ADF) function whereby the image is read while the original
94
is being moved by the feeding mechanism
95
and scanned.
As shown in
FIG. 1
, if the reading is executed in an FB mode, the controller
97
controls, upon power ON of the apparatus, the carriage driving mechanism
96
so that the electrooptical converter
92
is moved in a direction indicated by an arrow A
1
to reach a home position P
0
and stand by for an instruction signal. An original cover
98
is opened so that the original
94
is set in a platform
99
for an original. When an instruction to read an image arrives, a fluorescent lamp provided in the electrooptical converter
92
is turned on, whereupon the electrooptical converter
92
is further moved in the A
1
direction to reach a position P
1
so as to scan a reference plate
100
and read a reference whiteness level. Subsequently, the electrooptical converter
92
scans the original
94
so as to start reading the image thereon at a predetermined position P
2
. When the reading is completed, the electrooptical converter
92
is returned to the home position P
0
and stands by for a next instruction. In reading the original
94
, the reference whiteness level is used as an initial value, and other whiteness levels are successively made to follow the initial value. In this way, correction is made so that proper contrast is obtained.
If the reading is executed in an ADF mode, the controller
97
controls, upon power ON of the apparatus, the carriage driving mechanism
96
so that the electrooptical converter
92
is moved in the A
1
direction to reach a home position P
0
in the left half of the apparatus in FIG.
1
and stands by for an instruction signal. The original
94
is set in a shooter
101
. When an instruction to read an image arrives, the fluorescent lamp in the electrooptical converter
92
is turned on, and the electrooptical converter
92
is further moved in the A
1
direction to reach the position P
1
and read the reference whiteness level of the reference plate
100
. Subsequently, the electrooptical converter
92
is moved to an ADF reading position P
3
in the left half of the apparatus in FIG.
1
and stands by for an instruction. The feeding mechanism
95
is then driven so as to draw the originals
94
mounted in the shooter
101
one by one into the ADF. Reading is started from a predetermined position. The document
94
read is ejected to a stacker
102
.
The original
94
is guided by a backing part
103
so as to face directly opposite the electrooptical converter
92
.
FIG. 2
shows a conventional backing part
103
. In ADF reading, in order to ensure that a leading edge
94
a
of the original
94
is read, reading is started before the original
94
is transported to a reading position. The backing part
103
is read first, whereupon the original
94
is transported and read. Conventionally, the entire backing part
103
is painted in white in an assumption that the ground color of a commonly used original
94
is white.
The image processing unit
93
converts an analog electric signal from the electrooptical converter
92
into a digital signal on the basis of the reference whiteness level. In order to prevent data from being ruined by a level of the analog electric signal becoming higher in brightness level than the reference whiteness level, a conventional apparatus is equipped with a circuit whereby the electric signal is compared with the whiteness level required for conversion of the analog electric signal into the digital data. When it is determined that a difference between the analog electric signal and the whiteness level exceeds a predetermined level, the analog electric signal is made to indicate the whiteness level to make sure that the ground color of the original is white. Since image reading is started at the backing part
103
in the ADF, the color (white) of the backing part
103
is read first, whereupon other whiteness levels are made to follow. That is, a white-level following operation is started at the leading edge of the original.
It is to be noted that an original read by an image reading apparatus can be an original characterized by a contrast between the ground color of the original and a line drawing etc. on the original, or an original like a photograph whose image representation does not depend on the ground color.
The original which contains a line drawing etc. does not necessarily have the ground color of white. Hence, in order to obtain optimal contrast, a white-level following operation for determining the whiteness level should be carried out in accordance with a read signal. A reading mode wherein a reading is executed while whiteness levels are made to follow the ground color is referred to as a line art mode.
An image on an original such as a photograph is represented without the ground color being shown. An image true to the original cannot be obtained if a white-level following operation is conducted on an original such as a photograph. In this type of original, an image is read such that the reference whiteness level is determined by employing white as the fixed reference color. An image reading mode wherein the reference whiteness level is determined by employing white as the fixed refere
Kanemitsu Norio
Saito Keiichi
Wada Minoru
Fujitsu Limited
Grant II Jerome
Staas & Halsey , LLP
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