Facsimile and static presentation processing – Static presentation processing – Attribute control
Patent
1983-09-26
1986-04-29
Groody, James J.
Facsimile and static presentation processing
Static presentation processing
Attribute control
358 41, 358 50, 358 55, 358209, 358225, 358294, 250578, H04N 146, H04N 904, H04N 5257, H04N 1028
Patent
active
045860769
DESCRIPTION:
BRIEF SUMMARY
This invention concerns scanners of the kind where an original information bearing record such as a photographic negative or positive is scanned in a point to point manner by a spot of light and the spot of light is modulated by the information carried by the record. The modulated spot of light is passed to a photomultiplier or like photosensitive device and an electrical signal is generated which corresponds to the instantaneous information carried by the original at that point. Such an apparatus may form part of a telecine apparatus, a photographic printer, a facsimile transmitter or a document copier.
One method of scanning in a point to point manner is to utilise a cathode ray tube and to provide a raster on the face thereof. The raster is imaged on the original information bearing record and the transmitted modulated light, if the original is transparent such as a photographic negative or positive, is detected. It is known, however, to utilise a point light source and appropriate optical components to obtain point to point scanning.
In the case of a transparency, specularly transmitted light causes few problems and a simple optical path, which may include beam splitters, to one or more photomultipliers or like photo-responsive devices, can be used.
One problem that arises in scanners is if the original is dirty or scratched, the light transmitted thereby, if a transparency, is scattered and a proportion is not normally received by the photomultiplier or like photoresponsive device. The output signal of the photomultiplier indicates a high density at such a point on the original and, in a photographic printer where the original is a photographic negative, the reproduction shows a scratch as a white line and a speck of dirt as a white spot. A corresponding readily visible defect appears on the television screen of a telecine apparatus.
An electronic partial solution to this problem in telecine apparatus is described in U.K. Patent Specification No. 1,409,153, and another electronic partial solution to this problem in an electronic motion picture printer is described in U.S. Pat. No. 2,947,810.
The problem is made worse in colour scanners in that optical components are necessary to split the beam of modulated light into, for example, three colour components, usually red, blue and green. This beam splitting may be affected by partially silvered mirrors followed by appropriate colour filters and respective photomultipliers or, more efficiently, by dichroic mirrors and respective photomultipliers both as described in U.S. Pat. No. 2,947,810. In beam splitting, unless arrangements are made to contain scattered light, further light losses occur even when using dichroic mirrors. These losses are far greater for scattered light which does not impinge on the mirrors at or near the design angle, usually 45.degree.. Whenever a scratch or speck of dirt on the original is scanned, the output of the photomultiplier(s) or like photo-responsive device(s) normally drops due to light lost by scattering.
It is an object of the present invention to overcome this problem in a simple optical manner.
In accordance with the present invention, there is provided a colour scanner comprising a gate whereat a transparency to be scanned may be located, means for scanning the transparency in a point to point manner with a spot of light from a scanning beam, a beam splitter located so as to receive light transmitted by the transparency, a photomultiplier or like photoresponsive device located in spaced relationship to each exit of the beam splitter, and internally reflective optical path defining means between the gate and the entrance of the beam splitter.
The optical path defining means may comprise internally reflective mirror boxes and/or lenses for containing and directing modulated light from the transparency or other information bearing record to the entrance of the beam splitter. There may be similar optical path defining means from the exits of the beam splitter to the detecting surfaces of the photomultipliers or like photor
REFERENCES:
patent: 1781800 (1930-11-01), Baird
patent: 2947810 (1960-08-01), Horsley
patent: 3035179 (1962-05-01), Parker
patent: 3617752 (1971-11-01), Page et al.
patent: 3624286 (1971-11-01), Bosomworth et al.
patent: 3663750 (1972-05-01), Besier
patent: 4225782 (1980-09-01), Kuppenheimer, Jr. et al.
patent: 4481414 (1984-11-01), Gasper
Morse, D. R., "A Review of Telecine Systems," Journal of the SMPTE, vol. 73, Jul. 1964, pp. 548-560.
Seddon, R. E., "Interference Filters for Colormetric Applications," Proc. of the Suc. of Photo-Optical Instrumentation Engineers, vol. 50 (Optical Coatings), Aug. 1974, pp. 153-162.
Eastman Kodak Company
Groody James J.
Svihla Randall S.
Woods David M.
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