Image analysis – Image transformation or preprocessing – Changing the image coordinates
Reexamination Certificate
1998-01-06
2001-04-17
Couso, Yon J. (Department: 2623)
Image analysis
Image transformation or preprocessing
Changing the image coordinates
C382S321000, C358S486000
Reexamination Certificate
active
06219463
ABSTRACT:
This application is based on application No. 9-345237 filed in Japan, the content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an image reading device including a reading optical system which is able to read an image with a variable magnification.
In an image reading device including a reading optical system which is able to read an image with a variable magnification, a sub-scanning speed is determined at a designated magnification ratio (set value). This magnification ratio may be made variable by means of a zoom lens or made variable by moving the conjugation length of a single-focus lens.
However, in a case where the zoom lens is used or in a case where the single-focus lens is used, there is a problem that, when a reading magnification ratio deviates from the set value due to a mechanical error and the sub-scanning speed is determined with the designated magnification ratio kept intact, a state in which the aspect ratio of an image is disordered occurs as a consequence of a change of a relative relation between a sub-scanning magnification ratio and a main scanning magnification ratio since a line cycle of a main scanning is constant.
Particularly when executing partial magnification of an image, in general, it is often the case where a magnification ratio considerably greater than the magnification ratio in the case of normal paper size change is set. In this case, an error of the aspect ratio of the image tends to become relatively conspicuous on the image.
SUMMARY OF THE INVENTION
In view of the above, the object of the present invention is to provide an image reading device capable of preventing the disorder of the aspect ratio of an image even when the reading magnification ratio deviates from a set value due to a mechanical error and easily obtaining an accurate image.
In order to achieve the above object, there is provided an image reading device comprising:
an image reading unit which extends in a main scanning direction;
a projecting device which projects an image of an original document on the image reading unit;
a moving device which moves the image reading unit in a sub-scanning direction relative to the original document;
a magnification ratio detecting device which detects a magnification ratio of an image projected by the projecting device; and
a sub-scanning travel speed controlling device which controls a travel speed in the sub-scanning direction by means of the moving device according to the detected magnification ratio.
In the image reading device of the first aspect of the present invention, the magnification ratio detecting device detects the actual projection magnification ratio by the projecting device, and the sub-scanning travel speed controlling device controls the sub-scanning speed of the moving device in the sub-scanning direction to the sub-scanning speed corresponding to the projection magnification ratio.
As described above, according to the first aspect of the present invention, the sub-scanning travel speed controlling device controls the sub-scanning speed based on the actual projection magnification ratio detected by the magnification ratio detecting device. This arrangement is capable of setting the sub-scanning speed corresponding to the actual projection magnification ratio regardless of the presence or absence of a magnification ratio error attributed to a mechanical error in the zooming stage on the lens side, preventing respective relative deviations of a sub-scanning magnification ratio and a main scanning magnification ratio and preventing the disorder of the aspect ratio of the image, thereby allowing an accurate image to be obtained.
In an embodiment of the present invention, the image reading unit is a plurality of CCDs arranged in a linear form.
In an embodiment of the present invention, the projecting device is a zoom lens.
In an embodiment of the present invention, the projecting device has a projection lens having a single focus and is able to change its projection magnification ratio by varying its conjugation length.
An embodiment of the present invention further comprises:
a designating device which designates the projection magnification ratio of the projecting device; and
a lens moving device which moves a lens included in the projecting device according to the designated magnification ratio.
According to the embodiment of the present invention, by designating the projection magnification ratio of the projecting device by the designating device and moving the lens included in the projecting device according to the projection magnification ratio by the lens moving device, the projection magnification ratio can be changed.
In an embodiment of the present invention, an image reading device comprises a reference mark to be projected on the image reading unit by the projecting device.
In an embodiment of the present invention, the magnification ratio detecting device detects the projection magnification ratio of the projecting device by means of information of an image of the reference mark.
According to the embodiment of the present invention, the magnification ratio detecting device can detect the actual projection magnification ratio from an image obtained by projecting the reference mark on the image reading unit by means of the projecting device.
In an embodiment of the present invention, the sub-scanning travel speed controlling device moves the image reading unit at a speed at which an image magnification ratio in the sub-scanning direction is the detected magnification ratio.
The present invention provides an image reading device comprising:
a line sensor which extends in a main scanning direction;
a zoom lens which projects an image of an original document on the line sensor while varying a projection magnification ratio;
a reference pattern arranged in the vicinity of the original document;
a moving device which moves the line sensor in a sub-scanning direction relative to the original document;
a magnification ratio designating device which designates a projection magnification ratio of the zoom lens;
a zooming device which executes zooming of the zoom lens according to the magnification ratio designated by the magnification ratio designating device;
a reading device which reads an image of the reference pattern projected by the zoomed zoom lens by means of the line sensor;
a magnification ratio calculating device which calculates a projection magnification ratio according to image information obtained by the reading device; and
a sub-scanning travel speed controlling device which controls the moving device so that the line sensor moves in the sub-scanning direction relative to the original document at a speed corresponding to the calculated projection magnification ratio.
In an embodiment of the present invention, the line sensor has a plurality of CCDs.
In an embodiment of the present invention, an image reading device comprises a reference mark to be projected on the line sensor by the projecting device.
In an embodiment of the present invention, the magnification ratio calculating device detects the projection magnification ratio of the zoom lens by means of information of an image of the read reference mark.
In an embodiment of the present invention, the sub-scanning travel speed controlling device moves the line sensor at a speed at which an image magnification ratio in the sub-scanning direction is the detected magnification ratio.
The present invention provides an image reading device comprising:
a line sensor which extends in a main scanning direction;
a projection lens which projects an image of an original document on the line sensor;
a reference pattern arranged in the vicinity of the original document;
a sensor moving device which moves the line sensor in a sub-scanning direction relative to the original document;
a magnification ratio designating device which designates a projection magnification ratio of the projection lens;
a lens moving device which moves the projection lens according to a magnification ratio designated by the magn
Couso Yon J.
McDermott & Will & Emery
Minolta Co. , Ltd.
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