Photocopying – Projection printing and copying cameras – Copying both sides of original
Reexamination Certificate
2000-01-20
2001-11-27
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Copying both sides of original
C355S040000, C358S447000
Reexamination Certificate
active
06323933
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to image reading (or readable) devices and methods, and more particularly to a double-sided image readable device and method. A double-sided image readable device means a device that serves to read front and rear surfaces of a document simultaneously. The present invention is suitable for double-sided readable image scanners, copiers, facsimile machines, electrophotographic devices having flat bed unit and automatic document feed (“ADF”) unit (or a sheet feed unit). A flat bed unit means a type that uses an optical system to read a document statically placed on a glass board, while an ADF unit means a type that automatically and mechanically feeds a document paper so as to read it using a static optical system.
As recent demands for effective use of resource have increased opportunities to use documents having images on its both sides, high-speed and high-resolution double-sided readable image scanners that may read the images on both document sides have been sought. An image scanner converts data indicative of lightness and density for each pixel color that has been obtained by scanning, into digital data as a result of comparison with white and black reference data. A double-sided readable image scanner typically includes flat bed and ADF units, a first optical system at the flat bed unit side, a second optical system at the ADF unit side, first and second white reference boards, and first black reference board. These white and black reference boards are fixed onto a housing. The first optical system reads one document surface, whereas the second optical system reads the other surface of the document. Each optical system includes a fluorescent lamp and CCD sensor, and reads the document by emitting lamplight onto the document and converting the reflection light into an electronic signal using the CCD sensor. The first white and black reference boards are arranged apart from a document feed path, and used as white and black references, respectively, for the first optical system. The second white reference board is located below the document feed path and used as white and black references for the second optical system.
In general, an image scanner corrects white and black reference data at the beginning of reading and at an appropriate intermission during a reading of a large amount of pages (for instance, every 50-page reading) in order to correct a change in quantity of lamp's light and the sensitivity dispersion of photosensitive pixels in the CCD sensor. According to the conventional correction method of white and black reference data, the first optical system, which is movable, moves to the first white and black reference boards and reads them while the lamp turns on. The second optical system, which is not movable, reads the second white reference board just below the feed path while the lamp turns on and sets the resultant value as a white reference. In addition, the second optical system reads the second white reference board while the lamp turns off and sets the resultant value as a black reference.
White and black reference values are generated as one line pixel data from the read white and black reference data, and stored in a memory. In reading the document, these white and black reference values are used for correction of image data (which is referred to as “shading correction”).
However, external leakage light that reaches the second white reference board even when the fluorescent lamp turns off would cause the second white reference board to be incomplete or whitish black. Light black set as a black reference, or recognition of white as black would cause a read image to be more blackish than an actual image, disadvantageously preventing a high-resolution image reading.
BRIEF SUMMARY OF THE INVENTION
Therefore, it is an exemplified general object of the present invention to provide a novel and useful image reading device and method in which the above disadvantages are eliminated.
Another exemplified and more specific object of the present invention is to provide an image reading device and method that would realize a high-resolution image reading.
In order to achieve the above objects, an image reading device of one aspect according to the present invention comprises a first optical system which reads one surface of a document, a drive part which moves the first optical system, a second optical system which reads the other surface of a document, first white reference part and first black reference part readable by the first optical system moved by the first drive part, second white reference part and second black reference part readable by the second optical system, at least one of the second white and black reference parts being arranged to be movable, and a control part which controls the first optical system, drive part, and second optical system. This image reading device movably arranges at least one of the second white and black reference parts, and enables the second optical system to read the one reference part. Therefore, the second optical system may read both of the second white and black reference parts even when the other of the second white and black reference parts is fixed.
An image reading method of another aspect of the present invention comprises a first step of reading one surface of a document using a first optical system and the other surface of the document using a second optical system, a second step of moving the first optical system and first white reference part relative to each other, and reading the first white reference part using the first optical system, a third step of moving the first optical system and first black reference part relative to each other, and reading the first black reference part using the first optical system, a fourth step of moving one of second white reference part and second black reference part relative to each other, and reading the one of the second white and black reference parts using the second optical system, and a fifth step of reading the other of the second white and black reference parts using the second optical system. Such a reading method may realize the above operation.
Other objects and further features of the present invention will become readily apparent from the following description of the embodiments with reference to accompanying drawings.
REFERENCES:
patent: 5146351 (1992-09-01), Maehara
patent: 5745253 (1998-04-01), Muramatsu et al.
patent: 6088138 (2000-06-01), Sakai et al.
patent: 6122077 (2000-09-01), Kaji
Patent Abstract of Japan No. 5-14717, dated Jan. 22, 1993.
Patent Abstract of Japan No. 7-32711, dated Feb. 3, 1995.
Patent Abstract of Japan No. 7-193680, dated Jul. 28, 1995.
Patent Abstract of Japan No. 9-233321, dated Sep. 5, 1997.
Adams Russell
Armstrong Westerman Hattori McLeland & Naughton LLP
Fujitsu Limited
Nguyen Hung Henry
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