Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
2000-11-15
2004-06-15
Coles, Edward (Department: 2622)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S471000, C358S474000, C358S494000
Reexamination Certificate
active
06750990
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an image scanning apparatus, image forming apparatus, image forming system, image scanning control method, and storage medium and, more particularly, to an image scanning apparatus which can make generation of a black stripe image due to dust harder when sheetfed scans are made using a combination of a linear image sensor and an automatic document feeder attached to the image scanning apparatus, an image forming apparatus, an image forming system, an image scanning control method, and a storage medium.
BACKGROUND OF THE INVENTION
Conventionally, an image scanning apparatus with a linear image sensor has an arrangement shown in, e.g., FIG.
13
.
FIG. 13
is a block diagram showing an example of the arrangement of a conventional image scanning apparatus. Referring to
FIG. 13
, reference numeral
101
denotes a document illumination lamp;
102
to
104
, first to third mirrors;
105
, a lens;
106
, a linear image sensor;
107
, a platen glass;
108
, a document;
109
, a white plate serving as a reference for shading correction; and
110
, a dummy glass. The image scanning apparatus shown in
FIG. 13
can two-dimensionally scan the document
108
by moving (sub-scanning) the first to third mirrors
102
to
104
and the document illumination lamp
101
in the direction of an arrow.
FIG. 14
is a block diagram showing an example of the arrangement when an automatic document feeder is attached to the conventional image scanning apparatus shown in FIG.
13
. An automatic document feeder
200
comprises an automatic document feeding conveyor belt
202
, driving roller
203
, and document loader
204
, and conveys a document
201
loaded on the document loader
204
by rotating the automatic document feeding conveyor belt
202
by the driving roller
203
.
As an image scanning mode that uses the aforementioned image scanning apparatus and automatic document feeder, a “sheetfed scanning” mode is known. In the “sheetfed scanning mode”, the image scanning apparatus moves the mirrors to scan a predetermined position of the platen glass, and the automatic document feeder moves a document at a given speed in that state, thereby scanning an image of the document. That position on the platen glass which is scanned by the image scanning apparatus is called a “sheetfed scanning position”, and is constant, as indicated by the broken line in FIG.
15
. On the other hand, the automatic document feeder moves a document in the direction of an arrow in FIG.
15
. In this sheetfed scanning mode, since the document need only be moved in a given direction, the time interval required between neighboring documents upon successively scanning a large number of documents is shorter than that required in the normal scan.
However, the aforementioned prior art suffers the following problem. That is, in the sheetfed scanning mode, if dust, soil, or the like is present on a portion of the platen glass, as shown in
FIG. 15
, a black stripe forms at the corresponding main scan position of the scanned image. However, as a conventional method of preventing a black stripe from forming, the platen glass surface can only be cleaned.
SUMMARY OF THE INVENTION
The present invention has been proposed to solve the conventional problems, and has as its object to provide an image scanning apparatus which detects generation of a black stripe formed due to dust, soil, or the like on a platen glass in the sheetfed scanning mode, and makes control for changing the sheetfed scanning position or displays a warning indicating that dust or soil is attached to the platen glass in accordance with the detection result, thus reducing the frequency of occurrence of generation of a black stripe, an image forming apparatus, an image forming system, an image scanning control method, and a storage medium.
In order to achieve the above object, an image scanning apparatus for scanning an image while moving a document on a platen glass at a constant speed, comprises black stripe image detection means for detecting the presence/absence of generation of a black stripe image on the basis of an image signal obtained by the image scan, and control means for, when the black stripe image detection means detects generation of the black stripe image, determining that dust or soil is attached to a surface of the platen glass, and making control for changing a stop position of an optical system for guiding light reflected by the document to an image scanning system in the image scan.
According to a preferred aspect of the present invention, the apparatus further comprises document moving means for moving the document on the platen glass in a sub-scan direction at a constant speed, optical system moving means for moving/stopping a mirror table, that supports a reflected light guide mirror as the optical system, to scan a predetermined position on the platen glass, document illumination means for illuminating the document, that moves along the surface of the platen glass, at a stop position of the mirror table, and image scanning means serving as the image scanning system for scanning the image from the document, which moves at the constant speed, at the stop position of the mirror table.
According to a preferred aspect of the present invention, the black stripe image detection means comprises binarization means for binarizing image data scanned by the image scanning means, accumulation means for accumulating the binary data for a predetermined number of lines at N-line intervals (N: an arbitrary integer) in units of pixels, and comparison means for comparing the accumulation result with a predetermined determination level, and determining that a black stripe image is generated at the corresponding pixel position when the accumulation result has exceeded the determination level.
According to a preferred aspect of the present invention, the black stripe image detection means comprises black signal thickening means for selecting and outputting one with a smaller level of signals obtained before and after image data scanned by the image scanning means is delayed by a predetermined number of pixels in a main scan direction, binarization means for binarizing data scanned output from the black signal thickening means, accumulation means for accumulating the binary data for a predetermined number of lines at N-line intervals (N: an arbitrary integer) in units of pixels, and comparison means for comparing the accumulation result with a predetermined determination level, and determining that a black stripe image is generated at the corresponding pixel position when the accumulation result has exceeded the determination level.
According to a preferred aspect of the present invention, a timing at which the black stripe image detection means detects the presence/absence of generation of the black stripe image is set before a document scan by the image scanning means, and the black stripe image detection means detects the presence/absence of generation of the black stripe image using image data scanned at the predetermined position on the platen glass by the image scanning means while moving a belt surface of a document conveyor belt that forms the document moving means by the control means.
According to a preferred aspect of the present invention, a timing at which the black stripe image detection means detects the presence/absence of generation of the black stripe image is set after a document scan by the image scanning means, and the black stripe image detection means detects the presence/absence of generation of the black stripe image using image data scanned at the predetermined position on the platen glass by the image scanning means while moving a belt surface of a document conveyor belt that forms the document moving means by the control means.
According to a preferred aspect of the present invention, a timing at which the black stripe image detection means detects the presence/absence of generation of the black stripe image is set between neighboring documents upon successively scanning documents by the
Canon Kabushiki Kaisha
Coles Edward
Gibbs Heather D
Morgan & Finnegan , LLP
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