Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
2000-03-08
2003-03-04
Lee, Cheukfan (Department: 2622)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S490000, C358S487000, C399S378000, C399S377000, C355S075000
Reexamination Certificate
active
06529295
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an image scanner, and more particularly, to the handling of a sheet formed original before and during scanning in an image scanner.
BACKGROUND OF THE INVENTION
Two different classes of image scanners are known in the art. Flatbed scanners and drum scanners.
In a flatbed scanner, the original to be scanned has to be held extremely flat in order for all areas of an image on the original to be positioned in focus of the optics of the image scanner during recording of that area. For this purpose, the original is typically placed in a holder comprising two holder parts with glass plates. The original may be clamped between the two glass plates.
It is a disadvantage of known holders for flatbed scanners that the manual attachment of the original in the holder does not assure complete contact between the original and the glass plates so that Newton rings may be created by the partial separation between these surfaces.
It is a another disadvantage that the holder requires regular and careful cleaning to avoid dust and dirt to accumulate on the glass surfaces. Dirty surfaces impair the quality of scanned images and may scratch originals.
It is yet another disadvantage that the holder requires careful handling to keep the glass plates free of scratches.
It is still another disadvantage that the accurate positioning of the original in the holder require skills of the operator and is tedious and time consuming.
It is a further disadvantage that the holder can not apply sufficient strong forces to the original to stretch it to the required planar form. Typically, the original forms concave and convex buckles between the glass plates of the holder.
In a drum scanner, the original to be scanned is mounted on a transparent image reading drum. The original is manually attached and fixed onto the cylindrical surface of the image reading drum with adhesive tape, and is detached from the drum by peeling the adhesive tape off the original.
It is a disadvantage of the drum scanner that the attachment of the original to the drum does not assure complete contact of the original with the image reading drum, and in many cases, its poor contact with or partial separation from the drum causes Newton's rings.
It is another disadvantage of the drum scanner that because of the high rotational speed of the drum, the original has to be firmly attached to the drum to withstand high centrifugal forces. The firm mounting of the original requires skill and is time consuming.
SUMMARY OF THE INVENTION
The general object of the invention is to provide an improved user friendly method of feeding an original into an image scanner, an image scanner utilizing such a method, and a holder for holding an original before and during scanning in an image scanner utilizing such a method.
The terms sheet formed original and original refer to any flat object suitable for scanning, such as paper printed with signs, such as letters, drawings, graphical symbols, etc, photographs, transparencies, etc.
It is a further object of the present invention to provide an image scanning method and apparatus wherein the original need not be mounted between sheets or plates of transparent materials, such as glass.
It is a still further object of the present invention to provide an image scanning method and apparatus wherein the original need not be mounted with adhesive tape.
According to the invention these and other objects are fulfilled by a method of scanning a sheet formed original in an image scanner including supporting means for supporting a sheet formed original, imaging means, such as optics, such as a lense, etc, and light detecting means, such as a CCD, etc, said method comprising imparting a substantially cylindrical shape, such as a circular cylindrical shape, etc, to at least part of the original to be supported by the supporting means, moving the imaging means and the supporting means in relation to each other in a direction substantially parallel to the generatrix of the cylindrical surface.
Further, according to the invention the above mentioned objects are fulfilled by an image scanner for scanning a sheet formed original comprising light detecting means for detection of light transmitted from the original, imaging means for imaging at least part of the original onto the light detecting means, supporting means for maintaining at least part of the original in a substantially cylindrical shape, and first moving means for moving the imaging means and the supporting means in relation to each other in a direction substantially parallel to the generatrix of the cylindrical part of the original.
Preferably, an image scanner according to the present invention comprises a solid state imaging device, typically a charge coupled device (CCD), for recording of an image. The CCD is an array of a large number of light sensitive elements connected to each other as an analog shift register. In each element of the CCD a charge is formed that is proportional to the light energy incident on the element during an integration period. The analog charge of each element is shifted serially out of the CCD and processed by signal processing electronics of the image scanner. Typically, the analog charges are converted to digital values whereby a digital representation of the scanned image is formed. The digital values may be further processed by signal processing hardware and software of the signal processing electronics before transmission to external equipment through an interface.
Typically, the CCD of the image scanner is a linear CCD in which the light-sensing elements are arranged in a single line. During scanning, the original is moved relative to the CCD array and the original is scanned one line at a time. For scanning color images, either filters can be placed in front of the array, which then makes three passes across the original during image scanning, or, preferably, a trilinear CCD array, which comprises three linear CCDs positioned side by side, is used. Each line of the trilinear CCD array is covered by its own color filter, typically in the form of dye that is painted over the elements.
In the present invention, the fact that all parts of the original are not scanned simultaneously is exploited to simplify the positioning of the original in the image scanner compared to known methods and image scanners.
For example in a preferred embodiment of the invention, the original is scanned by a trilinear CCD array, i.e. the original is scanned line by line, three lines at the time, one line for each color. Thus, at a specific time “only” the area of the original that is scanned by the trilinear CCD array at that time has to be positioned in focus of the imaging means of the image scanner while the remaining part of the original may be positioned anywhere and may adopt any suitable form. Thus, there is no need for all parts of the original to be kept flat and planar as required in known flat bed scanners.
According to the present invention, the original is kept flat and straight along a line to be scanned by imparting a substantially cylindrical shape, such as a circular cylindrical shape, to at least part of the original. The original is scanned along lines that are substantially parallel to the generatrix of the cylindrical part of the original.
It is a further advantage of the present invention that the bending of the original into a substantially cylindrical shape produces a small saddle-effect, i.e. the original becomes a small deflection along the line to be scanned towards the axis of the cylindrical part of the original. The imaging means of the image scanner becomes less expensive when it is designed to focus on a curved line than when it is designed to focus on a straight line. Preferably, the imaging means is positioned so that the original is deflected away from the imaging means.
To scan the original, the area of the original that is imaged onto the light detecting means, such as a CCD array, may be swept across the original, e.g. by moving the original in relation to sta
Heger Anders
Poulsen Christian
Birch & Stewart Kolasch & Birch, LLP
Imacon APS
Lee Cheukfan
LandOfFree
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