US2340317A - Facsimile recorder - Google Patents

Description

Feb. 1,"1944 RECEIVER W. G. H, Fl-NCH FACSIMILE RECORDER Filed July 31, 1937 III' INVENTOR.

William finch BY 2 Z Z ATTORNEY.

Patented Feb. 1, 1944 uni-TED STATES PATENT OFFICE FACSIMILE RECORDER- William G. H. Finch, Newtown, Conn., assignor to Finch Telecommunications, Inc., Passaic, N. J a corporation of Delaware Application July 31, 1937, Serial No. 156,625

(c1.1vs

3 Claims.

my co-pending application Serial No. 123,770,

filed February 3, 1937, now Patent No. 2,203,461,

granted June 4, 1940. The signals are transmitted as a modulated carrier wave having a fundamental frequency preferably in the range of two thousand cycles per second. The method of transmitting and receiving the picture are optemplate employing electro-static recording to increase the recording speed and quality of the reproduction. In a preferred embodiment I employ a carbon content paper coated with a mercury oxide film and break down the film in accordance with the received picture signals impressed thereon at a high voltage in a novel manner to obtain a reproduction which has shading variations corresponding to the varying picture signal intensities.

I have discovered "that by connecting a carbon content record sheet to the positive side of the picturesignals and connecting the moving stylus to the negative side thereof that the film of carbon particles released from the surface of the sheet during the electrostatic breakdown action thereof will not be collected at the stylus and thereby avoiding smudging of the reproduction.

It .is among the objects of my present inven-- tion to provide simplified recording apparatus for particular use in facsimile receivers to be used by laymen in the home so as to require a minimum "of skill and attention to obtain results of high quality; to provide a novel high speed continuous sheet facsimile'recording system employing electrostatic breakdown of a film on a sheet to render a contrasting image with respect to the color of the sheet and thereby make visible the picture to be reproduced; and to provide improved and simplified rectifier connections to the electrostatic breakdown electrode to prevent smudging of the picture.

These and further objects of my present in-' vention will become apparent in the following description in connection with the drawing, in

which:

Figure 1 is a schematic electrical diagram of a preferred arrangement for carrying out my in vention and Figure 2 is an arrangement for mounting the record sheet in the recorder unit.

The picture signals are preferably generated by a facsimile transmitter system as disclosed in tional and may be over land, wire or radio. For general application of the present system as a home-facsimile recorder, the radio broadcasting of the signals is employed. I v

The receiver i0 is responsive to the channel over which the modulated audio frequency car rier picture signals are transmitted. These signals are delivered to the push-pull transformer H as an audio frequency carrier current modulated by the picture signals. The secondary of the transformer H is connected to the push-pull tetrode amplifier stage l2--l2 through a potentiometer arrangement H for varying the output of the signals from the amplifier [2. The biasing resistor I4 is connected in series between the cathodes of the amplifier stage l2 and ground to provide suitable biasing potential for the amplifier stage. The anodes of the push-pull amplifier stage are connected to the primary of the output transformer l5. Suitable potential is applied to the anodes and screen grid electrodes of the push-pull. amplifier stage l2 as indicated.

The audiofrequency output from the pushpull transformer i5 is rectified by the double rectifier tube 86, the anodes I1 and I8 of which are connected to the outer terminals of the secondary of the transformer Hi. The output of the rectification stage existing at the terminals 20 and 2l consists of a varying uni-potential signal. Terminal 2!! connected to the center tap of the secondary of the transformer I5 is the negative potential; the terminal 2! connected to the cathode of the rectifier I6 is positive as will be understood by those skilled in the art.

The record sheet 23 is mounted in a roll 24 and is advanced past the oscillating stylus 25 line by line in accordance with the oscillation of the scanner system. A preferred manner for advancing the record sheet line by line and the structure for mounting the record'sheet is described in the Patent No. 2,109,109 referred to above. The recis held against the block 26 by a fiat spring 21,

as described in the co-pendin-g application referred to. The stylus 25 comprises a metallic pin which is mounted at the end of a scanner rod 28.

The rod 28 is secured at the end 30 of the vertically oscillated rod 3| by means of a set screw 32. The rod 28 is adjusted in a slot in the post 3|] to maintain the point of the stylus 25 in a light contacting arrangement with the surface of the sheet 23. A spring 33 is preferably inserted between the post 30 and a collar 34 attached to the rod 28 near the stylus 25 so as to facilitate in the adjustment of the position of the stylus 25.

A source of mechanical power, such as an electric motor driven at a predetermined speed (not shown) is connected to a shaft 35 coupled to the driven shaft 36 of the scanner system through an overrunning clutch-37. The driven shaft 36 oscillates the vertical scanner shaft 3| in a predetermined manner through the schematically indicated mechanism at 38. A preferred mechanism for performing the oscillation of the scan ner shaft 3| from a continuously driven shaft by means of mechanism located at 38 is also illustrated and described in detail in my Patent No. 2,109,109. The oscillation of shaft 3| causes the stylus 25 to move in the arc (defined by the radial dotted lines 3939 as shown in Figure 2) across the record sheet 23. It is to be understood that the record sheet 23 is advanced by a distance equal to the width of the scanning line once per oscillation of the stylus 25.

The record sheet 23 of my present invention preferably consists of a paper having a high carbon content to render it conductive and having a thin film of mercury oxide coated on the sensitive surface, namely, the surface contacting the stylus 25. A voltage applied between the stylus 25 and the metallic block 26 contacting the opposite side of the paper causes an electrostatic breakdown through the paper. The portion of the record sheet across which the discharge takes place is rendered visible. In the present case, the mercury oxide film is orange in color, covering the dense black paper. When breakdown occurs, the black paper is visible through the orange coating as a black line. The degree of the marking on the paper is determined by the magnitude of the voltage and, therefore, the relative shading of the picture being transmitted is reproduced as a black-white half-tone effect on the record sheet.

The rectified picture signals are connected to the scanning system in the following manner:

The negative terminal 20 is connected to the stylus25 through the cam switch 40 when the switch is connected to the contact 4|. The cam switch contact 4| is connected to the metallic post 30 through a pigtail lead 42. The post 3|] is conductively connected to the metal stylus 25 through the rod 28, The post 30 is insulated from the vertically oscillated shaft'3l and the driving system by means of an insulation piece 43, which mechanically connects the post 30 upon the rod 3|. The positive terminal. 2| from the rectified picture signal output is connected directly to the metal block 26 which contacts the,

actuating of the cam switch a described in my Patent No. 2,109,109 and to its actuation in the synchronizing system described in my Patent No. 2,069,061 which issued on January 26, 1937.

Energization of the sync ronizing magnet 46 during reception of the s nchronizing impulses attracts lever 48 away from the periphery oi the overrunning clutch 31 and prevents it from disengaging the clutch 31. The notch 49 in the surface of the stop plate of the overrunnlng clutch 31 would normally engage with the projection at the end of .lever 48 to disengage the clutch 3! and thereby stop the scanner movement. The synchronizing impulse causing energization of the magnet 46 raises the lever 48 and prevents the disengagement of the clutch 31 if the receiver is in proper synchronous and phase relat1on with the transmitter. This synchronizing action is also described in detail in the references referred to disclosing details of the synchronizing mechanism.

An important feature of my present invention resides in the connection of the carbon sheet proper to the metallic supporting block 26 which is connected to the positive side of the rectified picture signals, and the connection of the stylus 25 which coacts with the mercury oxide coating, to the negative side of the picture signals. This method of connection of the signals prevents smudging of the picture for the following reasons:

The carbon particles which result from the stylus movement over the record sheet and breakdown of the surface thereof are caused to remain at the surface instead of being attracted to the coating, it is to be understood that other electro-' lytic-type of record sheets for electrostatic breakdown by picture signals may be employed. Thus, for black-white picture recording, a coating of barium iodide upon the white record sheet will result in a black-white pict'ure reproduction if the record sheet is passed through the scanner mechanism herein described in a damp or slightly wet condition. With the carbon content paper I have employed successful operation using picture signals of the order of 400 volts a erage intensity and operated at 100 lines per inchat a rate of one inch per minute to produce half-tone effects of good quality.

I claim:

1. In a facsimile system operable on a continuous record sheet: a stylus arranged to continu-- ously contact the record sheet; means for oscil- 4 tact the record sheet; means for oscillating said scanner, and means for holding the record sheet in a position substantially perpendicular to the oscillation path of said scanner and curved in an are about said scanner with a radius substantially that described by the scanner whereby the record sheet coacts with the oscillated contacting scanner in a substantially linear marking in an oscillating means; and a spring on said arm between said scanner and oscillating means for adjusting the relationship between said scanner and said sheet.

3. In a facsimile system operable on a continuous record sheet: a stylus arranged to continuously contact the record sheet; means for oscillating said contacting stylus across said sheet comprising a scanner arm attached to said stylus; and means for holding the record sheet in a position substantially perpendicular to all positions of said stylus and curved in an are about said stylus with a radius substantially that described by the stylus, said stylus being arranged to mark the inside arced surface of the sheet, whereby the record sheet coacts with the oscillated contacting stylus in a substantiallyaperpendicular relation and in a straight line marking path on the sheet to compose a facsimile of the transmitted image, said scanner arm being slidably mounted on an oscillating member, said arm being slidable in a plane substantially perpendicular to that of the sheet; and means on said scanner arm between said stylus and said oscillating member for regulating the pressure of said stylus against said sheet.

WILLIAM G. H. FINCH.

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