Flat bed facsimile scanners

Claim 2

A flat bed scanner for scanning subject copy, said scanner comprising the combination of means for supplying a substantially collimated beam of light; an optical path for said light beam; deflection means in said optical path for sweeping the light beam from end-to-end of a scanning station, whereby a scanning spot of light is projected onto said subject copy while said optical path is varied in length; and lens means in said optical path for shaping said scanning spot and providing said spot with a depth of focus at least as great as the difference between the longest and shortest lengths of said optical paths so that the spot of light projected onto said subject copy has a substantially constant area.

Claim 3

A scanner in accordance with claim 1 wherein said light beam is supplied by a laser and initially has a substantially circular cross-section and said lens means is further adapted to modify the cross-section of said light beam so that said scanning spot is substantially elliptical with a minor axis in parallel alignment with said scanning station and a major axis oriented perpendicularly to said scanning station.

Claim 4

A scanner in accordance with claim 2 wherein said lens means is interposed between said laser and said deflection means and includes an anamorphic lens for elliptically shaping said scanning spot and for focusing said scanning spot at a predetermined focal distance, said focal distance being selected so that a locus of the points in said optical path at the focal distance from said lens means is substantially equidistant from the ends and center of said scanning station and within said depth for focus of all points of said scanning station.

Claim 5

A scanner in accordance with claim 2 further including means for advancing said subject copy transversely of said scanning station at a predetermined rate, and wherein said deflection means cyclically sweeps said light beam from one end to the other of said scanning station at a predetermined frequency, whereby said subject copy is scanned in accordance with a predetermined scanning pattern.

Claim 6

A scanner in accordance with claim 4 further including means coupled to said laser for stabilizing the light beam at a predetermined energy level while said beam is sweeping from said one end to said other end of said scanning station, whereby the intensity of the scanning spot is substantially constant.

Claim 7

A scanner in accordance with claim 5 wherein each cycle of said deflection means includes a predetermined flyback interval, and further including means coupled to said laser for reducing the energy level of said light beam to a relatively low level during each such flyback interval.

Claim 8

A scanner in accordance with claim 6 wherein said deflection means includes a flat mirror and a galvanometer-type driver coupled to said mirror for oscillating said mirror through a predetermined angle and about a fixed axis of rotation.

Claim 9

A scanner in accordance with claim 7 wherein said lens means focuses said scanning spoT at a predetermined distance from the axis of rotation of said mirror, whereby a locus of the focus is generated as said mirror is oscillated, said focus distance being selected so that the entirety of said scanning station is within the depth of focus for the scanning spot and so that the scanning station has each of its ends and its center substantially equidistantly spaced from said locus.

Claim 10

A scanner in accordance with claim 8 wherein said lens means includes an anamorphic lens for elliptically shaping the cross-section of said light beam.

Claim 11

A flat bed facsimile scanner for converting information borne by a subject copy into a corresponding video signal, said scanner comprising the combination of means for supplying a substantially collimated beam of light; an optical path for said light beam; deflection means in said optical path for sweeping said light beam from end-to-end of a scanning station thereby projecting a spot of scanning light onto said subject copy while causing lengthwise variations in said optical path; lens means in said optical path for shaping said scanning spot and providing said spot with a depth of focus at least as great as the difference between the longest and shortest lengths of said optical paths so that said scanning spot has a substantially constant area; and photoelectric transducer means in parallel alignment with and extending substantially from end-to-end of said scanning station for intercepting light transmitted from said subject copy in response to said scanning spot to thereby generate a video signal corresponding to the information borne by subject copy.

Claim 12

A flat bed facsimile scanner for converting information borne by a subject copy into a corresponding video signal, said scanner comprising the combination of means for supplying a substantially collimated beam of light; an optical path for said light beam; deflection means in said optical path for sweeping said light beam from end-to-end of a scanning station thereby projecting a spot of scanning light onto said subject copy while causing lengthwise variations in said optical path; lens means in said optical path for shaping said scanning spot and providing said spot with a depth of focus at least as great as the difference between the longest and shortest lengths of said optical paths so that said scanning spot has a substantially constant area; and photoelectric transducer means in parallel alignment with and extending substantially from end-to-end of said scanning station for intercepting light transmitted from said subject copy in response to said scanning spot to thereby generate a video signal corresponding to the information borne by subject copy.

Claim 13

A facsimile scanner in accordance with claim 10 wherein a scan line of predetermined length is defined as said beam is swept from end-to-end of said scanning station, and said transducer means includes a photoresponsive diode having a length at least equal to the length of said scan line, with said diode being positioned in parallel alignment with said scanning station.

Claim 14

A facsimile scanner in accordance with claim 11 wherein said lens means is further adapted for focusing said scanning spot at a predetermined distance beyond said deflection means whereby a locus of the focus for said scanning spot is generated as said beam is swept from end-to-end of said scanning station; said station having its ends and center equidistantly spaced from said locus, with the distance between the locus and the scanning station never exceeding the depth of focus for the scanning spot.

Claim 15

A facsimile scanner in accordance with claim 12 wherein said light beam is supplied by a laser and initially has a substantially circular cross-section, and said lens means includes an anamorphic lens for shaping said light beam so that said scanning spot is substantially elliptical with a minor axis in parallel alignment with the scanning station and a major axis oriented perpendicularly relative to the scanning station.

Claim 16

A facsimile scanner in accordance with claim 13 wherein said deflecting means repeatedly and periodically sweeps said light beam from one end to the other of said scanning station at a predetermined scanning frequency, and further including means for advancing said subject copy transversely of said scanning station at a fixed rate, whereby said subject copy is scanned in accordance with a predetermined scanning pattern.

Claim 17

A facsimile scanner in accordance with claim 14 wherein said subject copy is incrementally advanced transversely of said scanning station in steps of equal length and predetermined repetition rate, said repetition rate being selected to be an integer multiple of said scanning frequency, whereby a helical scanning pattern is approximated.

Claim 18

A facsimile scanner in accordance with claim 10 wherein the light beam is supplied by a laser and initially has a substantially circular cross-section, and wherein said lens means is further adapted for shaping said light beam to provide a substantiallY elliptical scanning spot and for focusing said scanning spot at a predetermined distance beyond said deflection means, whereby a locus of the focus for the elliptical scanning spot is generated as the light beam is swept from end-to-end of the scanning station; said scanning station having its ends substantially equidistantly spaced from the locus of the focus for the scanning spot and all intermediate points displaced from the locus by no more than said depth of the focus.

Claim 19

A facsimile scanner in accordance with claim 16 wherein said deflecting means includes a mirror and driver means coupled to said mirror for oscillating said mirror about a predetermined axis of rotation so that said light beam is periodically swept back and forth between the ends of said scanning station, and further including means coupled to said laser and synchronized with said driver means for stabilizing said light beam at a predetermined energy level while said beam is sweeping from one end to the other end of said scanning station and for reducing the energy of said light beam to a relatively low level while said beam is returning from said other end of said scanning station to said one end.

Claim 20

A facsimile scanner in accordance with claim 17 wherein said driver means comprises a galvanometer having a moving coil for supporting said mirror for rotation about said axis, and a periodic signal source coupled to said galvanometer coil for supplying a substantially ramp-like signal to energize said galvanometer.

Claim 21

A facsimile scanner in accordance with claim 18 wherein said subject copy is substantially opaque, and said transducer means comprises an elongated photosensitive diode extending essentially from end-to-end of said scanning station for intercepting light diffusely reflected for said subject copy in response to said scanning spot.