Facsimile and static presentation processing – Facsimile – Recording apparatus
Patent
1984-09-19
1986-10-28
Rubinson, Gene Z.
Facsimile and static presentation processing
Facsimile
Recording apparatus
350 64, H04N 104
Patent
active
046202358
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a scanning apparatus designed for scanning disc films. Disc films comprise a substantially circular disc of film with a hub or core whereby the disc may be mounted in appropriate apparatus for printing etc. It is convenient to rotate the disc to present, successively, annularly located sequential rectangular image areas on the film disc at, for example, a scanning or printing station.
Scanning or printing stations for film are known in which the film is moved in a first direction to effect "page" scan and is illuminated so as to provide point by point or line scanning in a direction perpendicular to the direction of page scan. When the film is in strip form, for example, 35 mm or 110 size film, the movements in the "page" scan direction is rectilinear. If the individual image areas are located on an annulus of the disc and the disc is rotated to provide page scan, the movement of each rectangular image area is angular and not rectilinear. This gives rise to a dynamic distortion similar in appearance to the static optically produced "keystone" distortion, as a radially innermost part of each rectangular image area moves a lesser distance than the radial outermost portion thereof.
It is known in the prior art to provide a rotating image of a stationary object by using what is known as a "dove" prism. An example of such a dove prism is to be found in U.S. specification No. 3 647 961.
The present invention has for its object the provision of a scanning apparatus and a scanning method in which a rotatably-mounted disc film can be scanned line by line whilst avoiding the keystone distortion which would normally be induced by rotation of the disc. The invention also provides a method of scanning a rectangular image area of a rotatable disc film, line by line without inducing rotationally-dependent distortion such as keystone distortion.
According to the present invention, there is provided a method of effecting line by line scanning of a rectangular image area of a plurality of such areas located annularly on a rotatable disc film, the method comprising the steps of indexing the disc about its axis to present the first of such areas at a scanning station, forming an image of a line of the rectangular image area on a linear CCD array in the scanning station, and moving the image so formed in a direction perpendicular to the linear CCD array to present images of successive lines of the rectangular image area on the CCD array.
The disc is rotated about its axis and optical means are arranged to correct the angular motion of the image of the rectangular image area to rectilinear motion perpendicular to the array.
In a preferred embodiment, the image is formed by an objective lens. The optical means comprises a dove prism or equivalent mirror box (hereinafter termed generally a "dove prism" for the sake of convenience) located on the optical axis of and at one side of the objective lens. The dove prism is rotated in the same sense as and at half the angular speed of rotation of the disc. It is preferred that, upon completion of the scan of each rectangular image area, the dove prism is returned to a start position whilst the disc is rotated further about its axis to present a next rectangular image area at the scanning station.
The CCD array is made longer than the image of a line to compensate for movement of the image parallel to the array.
The invention also provides an apparatus for line by line scanning disc films the apparatus comprising a scanning station, means for line scanning of an image annularly arranged in the disc at the scanning station, optical means for imaging the line scan on a CCD array, a dove prism or equivalent mirror box located on the optical axis, and means for rotating the disc about its axis and for rotating, at half speed, the dove prism about the optical axis.
The invention will be described further, by way of example, with referene to the accompanying drawings in which:
FIG. 1 is a plan view of a film disc of the kind which can be scanned without distortion, by
REFERENCES:
patent: 3441334 (1969-04-01), Marks et al.
patent: 3442575 (1969-05-01), Rosin
patent: 3647961 (1972-03-01), Blitchington, Jr. et al.
patent: 3715497 (1973-02-01), Cooper et al.
patent: 4094576 (1978-06-01), Heiling
patent: 4144542 (1979-03-01), Preuss
Eastman Kodak Company
Owens Raymond L.
Rubinson Gene Z.
Schroeder L. C.
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