Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1997-09-03
2001-05-15
Mancus, Joseph (Department: 2623)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S475000, C358S487000, C358S497000
Reexamination Certificate
active
06233063
ABSTRACT:
BACKGROUND
The field of the present invention is optical scanning of high-resolution color images, and in particular, the use of a flat-bed scanner system for the scanning of reflective and transmissive original documents at high resolution in a high volume production environment typical in the graphic arts electronic prepress industry. The original documents scanned by such systems include color or monochrome photographs, artwork, and composed pages of text and graphics. The actual graphic image content of the scanned original document is referred to as an “original”.
In use of a flat-bed scanner for reflective scanning, an original on an opaque substrate is placed with the surface containing the original facing down on a flat transparent reference surface, typically glass. The original document is fixed on the surface such that a single line of the original, herein after referred to as a “scan line” is illuminated from below, and the light reflected from the scan line is directed through an optical system to form an image of the scan line on a sensor such as a CCD array, which converts the optical signal to an electronic representation of the scan line, comprising a line of digital picture elements, or “pixels”. The desired portion of the original is scanned, one scan line at a time, by moving the original relative to the illumination system, optical system, and sensor along a direction hereinafter referred to as the “scanning axis”. In systems typical of the prior art, such as that disclosed in U.S. Pat. No. 5,341,225, the illumination system, optical system and sensor are configured to move together as a unit. In other systems, such as those of U.S. Pat. No. 5,140,443, the original is moved while the illumination system, optical system and sensor remain fixed. In a production environment, original documents are scanned in a sequence, with each requiring a preparation step in which the original to be scanned is located and fixed on the surface in proper alignment and registration, followed by the actual scanning operation.
A transparent original document, typically a photographic transparency, comprises an original on one side of a thin transparent substrate. In this case, the original is illuminated from the side opposite from that containing the optical system and sensor. Use of a single flat-bed scanner for both types of scanning involves a modal configuration change. Typically, a flipcover used in reflective scanning mode to hold the original document flat on the transparent surface is replaced by a transmissive illumination module which illuminates from above the portion of the original to be scanned. As in reflective-mode scanning, prior art systems are configured so that either the original or one or more scanner illumination, optics or sensor components move to carry out the scanning process.
In addition to reconfiguration of the illumination system, the magnification of the optical system is typically changed so that the same number of pixels imaged on the CCD array, and captured by the digitizing electronics, corresponds to a larger or smaller area of the original. In high-resolution scanning systems typically in use in graphic arts electronic prepress processing, transparencies are oftentimes scanned at resolutions of 2,000 to 4000 pixels per inch (ppi) or greater, while reflective originals are usually scanned at much lower resolutions, for example 600 to 800 ppi. Accordingly, in a production environment in which both reflective and transmissive originals are to be scanned in a mixed processing sequence, mode changes involving illumination system and resolution settings can add significantly to the time required for job processing.
Accordingly, it is an object of the present invention to provide a low cost apparatus for color scanning both reflective and transmissive original documents at a predetermined resolution.
It is yet another object of the present invention to provide a scanning apparatus for scanning transmissive original documents at low and high resolution.
It is a further object of the present invention to provide a converging device within the scanning apparatus which changes the resolution of the scanning system and automatically focuses the original document onto an image sensor.
Additional objects, advantages, novel features of the present invention will become apparent to those skilled in the art from this disclosure, including the following detailed description, as well as by practice of the invention. While the invention is described below with reference to preferred embodiment(s), it should be understood that the invention is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional implementations, modifications, and embodiments, as well as other fields of use, which are within the scope of the invention as disclosed and claimed herein and with respect to which the invention could be of significant utility.
SUMMARY OF THE INVENTION
The apparatus comprises a flat-bed scanner providing separate fixed object focal planes for transmissive and reflective originals, wherein a movable module, hereinafter referred to as a “scan carriage”, containing illumination, sensor, and optical elements is moved to scan an original. The movable scan carriage has an illumination source disposed between the two object focal planes, with the object focal plane to be used (transmissive or reflective) selected by changing the position of one or more optical elements within the scan carriage. The magnification of the optical system, i.e., the resolution of the digital representation of the original, can be adjusted independently of the selection of an object focal plane. A converging device is provided within the scan carriage for adjusting the resolution of the original image, singly or in combination with the motion of another mirror. The converging device includes at least a first and second optical lens mounted on a lens carriage and a drive device for moving either lens into an optical pathway containing an original image. The drive device may also be used to move the optical lenses closer to or further from an image sensor for automatically focusing the original image onto the image sensor.
The positioning of optical elements to select the object focal plane is the subject of several embodiments to be described in detail below. One or more mirrors can be moved so as to retain the total optical path length between the selected object focal plane and the sensor focal plane, i.e., the plane on which the original is imaged on the sensor.
The illumination system can be configured according to the object focal plane selected, using an elongated lamp disposed along an axis substantially parallel to the scan line axis of an original at the selected object focal plane. In the preferred embodiment, the single tubular lamp is disposed in the movable scan carriage such that the lamp is used to illuminate a scan line in both the reflective and transmissive modes using additional optical components, such as a switch mirror, to direct light to the directed object focal plane.
The transmissive object focal plane is fixed with respect to the scanning apparatus, located between the illumination system and the other optical components. In one embodiment, a removable transparency holder is used for access to the transmissive object focal plane, and for accurate placement of an original document to be scanned before insertion into the scanner. In alternate embodiments, the action of insertion or removal of the transparency holder is used, through appropriate linkages with illumination system elements and/or optical elements, to select the transmissive or reflective focal planes respectively.
The scan carriage is moved along a scanning axis from one end of the original to be scanned to the other, carrying the illumination, optics and sensor systems within it.
The use of a single switch mirror in combination with the resolution selection of the original image enables three distinct scanning modes: 1) reflective mode, low-
Bernasconi Matthew
Haded Kevin J.
Reznichenko Yakov
Agfa Corporation
Bali Vikkram
Kelley Edward L.
Mancus Joseph
LandOfFree
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