US 2379438 A
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Description (OCR text may contain errors)
July 3, 1945. v L, H AN 2,379,438
, FACSIMILE APPARATUS Filed May 22, 1942 INVENTOR Jfin l llji'o a/w ATTORNEY Patentedv July 3,1945
John V. L. Hogan,
of New York Forest Hills, N. Y., asslgnorto Faxlmlle. Inc., New York-N. Y., a. corporation Application May 22, 1942; Serlal'No. 444 005 9 Claims. .(cl. 178-71) The present invention concerns facsimile pickup scanners. 1
One obi ect of the present invention is to provide a. simple and eflicient facsimile pick-upscanner capable of scanning copy in continuous sheets or in short lengths and in any width up to a predetermined maximum.
Another object is to provide a simple and emcient illuminating system for scanning the copy.
A further object is to provide even illumination in conjunction with a simple photo-electric cell pick-u system.
A still further object is to provide a simple and eflicient motor drive for the scanner drum.
These and other objects of; the invention will.
be apparent from the detailed description of the invention given in connection with the various figures of the'drawing.
In order to transmit copy by wire line or radio for facsimile purposes signals representing the light and shade of the copy are usually generated by scanning trated light beam is usually directed upon the copy and the light, reflected from anelemental area utilized to actuate a photoelectric cell. Such .a system utilizes I the available light due to the inefllciency of conventional lens systems and to the low coeflicient of reflection of mostv copy. Another difflculty is encountered in scanning a long sheet of copy and most systems which are capable of doing this are very complicated. Y
- The present invention utilizes light'transmitted through thecopy, usually has been found to be a simple and efficient method. In scanning by transmitted light a simple and eflicient light system consists in a lamp with a long filament. Scanning is accomplished at the intersection drum and a linear stationary slit. The inside of the drum is silvered or painted white to reflect oi the light entering the a large percentage into two photo-electric cells.
photo-electric cells are used, eliminating difliculties arising from variable sensitivity along the length of a long photo-electric cell. Small variations in illumination along the scanning line are compensated by means of a variable density wedge or by making the linear slit slightly wider near its center. may be scannedin the present device by means of a simple sheet feeding mechanism. Copy of any width up to the length of the drum may be utilized.
the copy point by poin A concenonly a small traction ofv a paper sheet, and it of a helical slit in a rotating A Almost any length of copl constant speed by means of motor Further confining of thelight In the drawing: 1
Fig. 1 shows a general view of one formotthe present invention cut away Fig. 2 shows an end'view of the formoi'the invention shown in Fig. 1.
Figs. 3, 4 and 5 showvarious details'and modifications of the present invention.
Figs. 6 and '1 show light distribution diagrams useful in explaining the operation or the invention.
Fig. 1 shows one form of the present invention in which a cylindrical drum I having hollow. end shafts 4| and 42. is mounted in end bearings 3 and 2 carried by bed-plate 4. Drum I 'isirotated by a motor comprising v to, or an'integral part of; shaft 4| and stator poles 43 and 44. Also carried by bed-plate-4 are brackets 5 and 6 supporting photoelectric cells 7 drum l at or near its ends. Cell: I: includesv cathode l8 and anode nal utilization apparatus by'means of leads l5. and I6. Cell 1; includes cathode l2 and anode Hz and is connected to signal utilization apparatus by means of leads sand l1 andis connectedto siglll. Drum I is preferably formed of an opaquematerial, such as metal, and is silvered and polished. or painted white on its inside surface. Thru the walls of drum l is cut a helicalslit "passing. substantially once around the circumference. The scanning of copy is accomplished by rotating .drum l at a 43-44-45, sothat slit 19 moves repeatedly along an intersecting linear slot to be describedlater.
Fig. 2 shows an end view of thescanner shown in Fig. 1 showing the'relationof drum- I, photoelectric cell IS and slit iii to the remainder of the scanning apparatus. Either continuous copy 20 as shown passing from roll 21 to roll 28v may be scanned or'short pieces of copy may be fed into the scanning apparatus by, placing themv 1 by means of lamp 25 having a long straight illa- V ment 26. The light from filament is concentrated by means" of an optical system, such as reflector 39. The illumination of the copy is confined to a narrow line by means of aperture plate 31-48.
23, -21 or both. The slot l9 with the linear by apertures in. plates intersection of helical aperture forms the scanning elementwhich moves to show some details. 7
stator 45 directly attached may be produced across the copy. The scanning is completed by the downward motion of the copy.
By making aperture plate 2l--22 curved, and with the slit edges so thin as to be practically knife-edged, the copy may be passed over it and in contact with it at the linear aperture line. This contacting of the copy with the aperture accurately determines the scanning plane so that the image of lamp filament 26 may be accurately focused. Both the contact with the aperture and the fixing of the plane result in extremely fine definition of the scanning elemenigas it moves across the copy. Thus, fine detail may be obtained in scanning the copy with a simple and eflicient scanning device.
Pick-up of the light from the scanning process is carried out by means of a suitable photo-electric cell within drum l. While a long photoelectric cell may obviously be used, it has been found more practical to use one or two conventional cells mounted near the ends of the drum as shown in Fig. 1. By slivering or painting white the inside of drum 4, practically all the light enterin thru the scanning aperture and passing the helical slot I9 is reflected into cells I and i3 resulting in high eliiciency and even illumination along the linear scanning path.
If it is found that there is still a somewhat lower intensity of light at the center of the scanning path, as illustrated by the shade lines in Fig. 7. an aperture admitting more light at its center. as shown in Fig. 3, may be used. The compensating aperture between plates 2| and 22 has equal widths at its ends A and C while it is made wider at the center b to compensate the falling off of effective illumination which results when the scanning aperture is near the center of its travel. Fig. 3 is exaggerated, since, in general. the center portion need be made only slightly wider than the ends.
In the case of short drums or where less detail is required, one photo-electric cell may be used, as shown in Fig. 6, in which case the illumination falls toward the end away from the cell, as shown. The light distribution may be compcnsatecl in this case by means of an aperture wh'ch is made wider as it goes away from the cell. as shown in Fig. 5.
While the aperture between plates 2| and 22 is shown as the compensating aperture, it will be evident that the compensation may be applied to the other apertures, e. g. 2324, or that other means. such as a variable density wedge, or a lamp having varying light output along its length, may be used to accomplish the same thing, without loss of resolution.
Fig. 4 shows lamp .25 having a long filament 26, and seals 33 and 35 and leads 34 and 3B. Filament 26 may be coiled as shown or a straight wire as long as it gives a concentrated linear illumination of a narrow effective width.
Motor 434445 comprising field coils 43-44 and rotor 45 integral with or mounted directly on shaft 4| is Simple and eflicient and provides an accurate smooth drive for drum l.
The scanning system above described is also useful for recording facsimile signals. In recording. cells I and i3 are signal modulated glow lamps and sheet is a light sensitive record sheet, such as a sheet coated with a photographic emulsion.
While One embodiment and a few modifications have been shown and described, it will be evident to those skilled in the art that many modifications may be made within the spirit and scope of the invention as set forth in the appended claims.
What is claimed is:
1. In a facsimile scanner the combination of, a scanning drum including a helical slot. a pair of photo-electric cells, means for mounting said cells near the ends and inside said drum, a linear slot formed between two curved plates and ad- .iacent said drum, means for moving a copy sheet to be scanned over said curved plates, a linear light source for illuminating said linear aperture through said copy, and means for rotating said drum to linearly scan said copy at the intersection of said helical and linear apertures.
2. In a facsimile scanner the combination of, a rotatable drum carrying a helical aperture, a curved plate cut to form a linear aperture progressively wider along at least a portion of its length for forming an aperture of varying crosssection with said helical aperture, as said drum is rotated, means for moving a copy sheet to be scanned past said apertures, and means for evenly illuminating said sheet at least along a line immediately over said linear aperture.
3. In a facsimile scanner the combination of. a scanning device including a drum and a stationary plate, means comprisin a helical slot in said drum and a closely superimposed linear aperture in said plate forming a scanning aperture, and means for moving a copy sheet at a uniform rate past said linear aperture.
4. In a facsimile scanner the combination of, a scanning device including a rotatable drum and a stationary plate, means comprising a helical slot in said drum and a closely superimposed linear aperture of varying width in said plate forming a scanning aperture, and means for moving a copy sheet at a uniform rate past said linear aperture.
5. In a facsimile scanner the combination of, a rotatable drum carrying a highly reflecting inside surface and a helical slot through its sur face, apair of photo-electric cells, means for mounting said cells inside said drum adjacent its ends, a linear aperture plate closely adjacent to the outside surface of said drum, meansfor moving a copy sheet past said plate and substantially in contact with it at least in the region of the aperture, and means for illuminating said sheet at least in the region of said aperture.
6. In a facsimile scanner, the combination of, a rotatable drum, a pair of photo-electric cells mounted near the ends and inside said drum for generating signals in accordance with light entering said drum, 2. highl reflecting surface on the inside of said drum for reflecting light en-- tering said drum into said photo-electric cells, a helical aperture through the surface of said drum for partially defining a scanning aperture, means for defining a linear aperture closely superimposed upon said drum'to complete the defining of the scanning aperture, means for drawing copy to be scanned across said two apertures, means for directing light on to the copy on the side opposite the aperture, means for rotating said drum to cause said scanning aperture to pass successively across said copy to complete the scanning process, and utilization means connected to said photo-electric cells for utilizing the signals generated by the scanning process.
7. In a facsimile scanner, a rotatable drum having a narrow helical slot, and a stationary plate having a longitudinally extending narrow slot arranged close to the surface of the drum, a
translating device within the drum, the point of intersection of the two slots constituting a scanning aperture and means for moving a copy sheet past said aperture.
8. In a facsimile scanner, the combination of, a rotatable drum, means inside said drum for generating signals in accordance with light entering said drum, said drum having a helical aperture through the surface of saiddrum for partially defining a scanning aperture, means for defining a linear aperture closely superimposed upon said drum to complete the defining of the scanning aperture, means for drawing copy to be scanned across said two apertures, means for rotating said drum to cause said scanning aperture to pass successively across said copy tocomplate the scanning process, and utilization means for utilizing the signals generated by the scanning process.
9. In a facsimile scanner, a rotatable drum having a narrow helical slot, and a stationary plate having a longitudinally extending narrow,slot arranged close to the surface of the drum, a light source within the drum, the point of intersection of the two slots constituting a scanning aperture and means for moving a lightsensitive sheet past said aperture.
' JOHN v. L. HOGAN.