Optical: systems and elements – Lens – Anamorphic
Reexamination Certificate
2000-02-28
2001-11-06
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
Anamorphic
C355S025000, C355S052000, C399S118000
Reexamination Certificate
active
06313954
ABSTRACT:
FIELD OF INVENTION
The present invention relates to copying methods and apparatuses and, more particularly, to a method and apparatus for correcting for the distortion that results when copying pages of a book pressed against the document support glass of a copying machine or a document scanner.
BACKGROUND OF THE INVENTION
Ever since the introduction of xerographic photocopiers, many have experienced the difficulty in producing clear, non-distorted copies from opened books or volumes that have been pressed upon the flat document glass. This difficulty is mainly due to the fact that conventional photographic copiers are designed for producing copies from documents (generally, single sheets) that lay flat upon the document glass. Textbooks with hard bindings cannot be so oriented.
The crease of a typical textbook generally pyramids upwardly away from the glass, thus causing an upside-down, “V-shaped” surface. This is especially so for thick books with hard covers. The crease, therefore, falls outside of the focal length range for which the copier lens can properly project the image of the book onto the image receiving medium or pre-charged paper. In other words, the crease cannot be focused properly to provide an undistorted image. As a result, the copied crease is often blurred, distorted, and often darkened.
In order to make the copies more legible, the operator of the copier is required to forcibly press upon the backing of the book as it rests upon the glass. Sometimes this will work. However, many times the binding is too stiff, and the crease cannot be projected into the fold. Pressing with excessive force is also risky, as this may cause damage to the binding. In some cases, an immoderate force may even break the glass.
The present invention reflects the discovery that the aforementioned problem can be solved in a user friendly and inexpensive manner.
The current invention comprises a corrective lens that is shaped to fit in the space between the book pages to be copied and the document glass of the copier. This simple solution provides a surprisingly unblurred and undistorted image of the adjacent pages of the book extending into the fold of the crease.
DISCUSSION OF RELATED ART
In U.S. Pat. No. 3,609,030, issued to Meyer L. Sugarman et al. on Sep. 28, 1971, a tabletop electrostatic book copier is illustrated, which has an exposure station on its top. The book to be copied is placed on top of a vertical exposure station and the image of the book is projected directly to the pre-charged paper though a mirror and an optical lens. The image of the book surface is projected using an ordinary optical lens and a mirror found in conventional copiers. The image is projected directly onto a charged paper instead of onto an image receiving medium. There is no teaching or suggestion of using a distorted lens to refocus the page of the document.
In U.S. Pat. No. 4,585,334, issued to Brian R. Malyon on Apr. 29, 1986, a document copier is shown that incorporates a scanner with a forty five degree slanted scanning window glass mounted at the end of a rectangular housing. The ninety degree corner, or the so-called wedge, between the window glass and one of the side walls points downwardly. The book to be copied is placed on a rack below the scanner window glass. The rack is constructed from two flat frames connected together at a ninety degree angle, with its opening facing upward. The book to be copied is faced upwardly and rests on the rack with its inside pages opened at a ninety degree angle. During the copying process, the rack first moves up, bringing the half opened book towards the scanner. It then stops at a predetermined position and keeps a surface of the book page away from the scanner window to prevent causing damage to the book. At this position, the opposite inside page of the book is under the scanner housing, facing the side wall. It may or may not touch that slanted side wall. The scanner then scans the surface of the inside page of the book under its window.
In U.S. Pat. No. 4,763,173, issued to Michael E. Harrigan, et al. on Aug. 9, 1988, a document imaging system is shown including a positive, aspheric, Fresnel lens. The purpose of the system is to compensate for small, smooth wrinkles and curls of the original document to be copied.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provide a substantially flexible, freely movable, corrective lens that yields undistorted copies of adjacent book pages presented for xerographic copying or for scanning. The corrective lens is substantially rectangular in shape, in order to cover various sizes of books. The lens is placed between the spread pages of the book to be copied and the document glass of the copier. The corrective lens has a mid-portion or center section that extends into the crease of a typical book, where it changes the focal point of the text disposed at the inner edge of the pages. The lens extends outwardly from the center section to form substantially flat side portions, which structurally keep the pages of the open book in place during the copying procedure. This simple lens solution provides a surprisingly undistorted image of the adjacent pages of the book projecting into the fold of the crease, which is then transferred in typical fashion to the copying drum or charged surface of the copying medium or to the photoelectronic sensors of a scanner.
It is an object of this invention to provide an improved means for copying books upon a copying machine substantially free of distortion along a center crease thereof.
It is another object of this invention to provide means for compensating for the distance between the crease of a book and regions proximate thereto, during a photocopying process, that does not require complex structural modifications to conventional copying machines.
It is still a further object of this invention to provide a lens that acts as a wedge to spread the pages of a book closest to the binding thereof.
It is a further object of this invention to provide a freely movable lens for placement between an open book to be copied and the document glass of a copier, wherein the lens changes the focal point of the page edge along the crease.
REFERENCES:
patent: 3609030 (1971-09-01), Sugarman et al.
patent: 3635557 (1972-01-01), Alderton
patent: 4585334 (1986-04-01), Malyon
patent: 4763173 (1988-08-01), Harrigan et al.
patent: 5072252 (1991-12-01), Howseman, Jr.
patent: 55052073-A (1980-04-01), None
patent: 60186830-A (1985-09-01), None
patent: 63254437-A (1988-10-01), None
Epps Georgia
Salzman & Levy
Spector David N.
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