US2341315A - Telefacsimile system - Google Patents

Description

Feb. 8, I944.

\ A. G. COOLEY TELEFACSIMILE SYSTEM Filed April 15, 1942 INVENTOR I being received.

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UNITED STATES PATENT OFFICE 2341-315 TELEFAOSW SYSTEM Austin G. Cooley, New York, N. Y assignor to Times Telephoto Equipment Inc., New York, N. Y., a corporation of New York Application April 15, 1942, Serial No. 439,014

8 Claims. (Cl. 178-73) This invention relates to teleiacsimile systems and more especially to such systems of the taperecording type.

a principal object of the invention is to provide means for automatically controlling a facsimile receiving machine so that its driving'mechanism only operates while facsimile signals are Aifeature of the invention relates to a telefacsimile receiving system of the tape-recording type wherein the space and mark signal conditions control the operation or non-operation of the tape driving motor. I

A further feature relates to a novel and sim standing of the inventive concept. Accordingly ,I in the drawing, the block [designates schematirent flow and marking signals are represented by absence of current At the receiving end ofthe signalling channel L. the signals are passed through a suitable detector and amplifier 2 and preferably they are converted into 1). C. signals which are impressed upon a pair of grid-controlled tubes 8. l. Tubes land 4 are so connected that for weak signals or no signals, corresponding to a mark condition,

the tube 3' passes plate current while the tube 4 is biassed to substantial plate current cutoii.

0n the other hand, when a strong signal corresponding to spacing, is received, the tube 4 becomes plate conductive while the tube 8 becomes biassed to substantial plate current cutofl. In other words. the tube 3 passes current under control of a received mark signal while the tube I passes current in response to a received space signal. The plate circuits of the tubes 3 and l are connected in balanced relation through two operating windings I and i and through the plate cally anywell-knownform of telefacsimile signal transmitter, whereby the intelligence to be transmitted is converted into two signal conditions, e. g., marking and spacing. For this purpose, device I may be a facsimile or telegraph transmitter which controls the production of signal current of two different levels, the lower level representing for example marking, and the upper level representing for example spacing or vice versa. Device I may include a facsimile scanning mechanism of any known construction such for example as a scanning drum around which is formed the printed matter to be transmitted, and as a result of which the white areas are I translated into an audio frequency carrier, for

example one of 1800 C. P. 8., and the black areas are translated into an 1800 C. P. 5. carrier of a different amplitude. Fora detailed description of such mechanism,reference-may be had to my supply battery I. Associated with the windings 5 and I isan armature or bar 8 mounted for swinging movement and adapted to be actuated in one direction or another depending upon whichof the windings I, I, is energized. -'lhe 7 member I cooperates with any well-known formof facsimile recorder represented schematically by the drum rotating 9. Merely by way of example, drum l'may have around its periphery in helical form a rib or knife edge "I and the member i may carry a knife edged bar II which extends substantially parallel to the axis of drum 9, a suitable movable recording web or tape I! being positioned between bar ii and the knife edge In. When the member I is in'spacing po- 'sition, the bar II is clear of the recording paper If. when a marking signal is received, bar II is moved to engage the recording paper whereupon a suitable mark is made thereon. For this purpose the recording can be effected by means of an inked ribbon or carbon transfer paper positioned between the bar it and the recording web II; or. if desired, the rib II can be inked by a suitable inking roller as described in application Serial No. 418,172, filed November 7, 1941. thus avoiding the use of a separate inked ribbon or carbon paper. For a detailed description of one preferred form of control circuit for the tubes 3 and 4, reference may be had to application Berial No. 397,513, filed June 11, 1941. g

It will be understood of course that the motor M which drives the drum 9 may also control the feeding of the tape l2. However, it is highly desirable that the tape and scanning drum 9 be 'mark condition.

spacing signals are received, the armature H is a inert when no facsimile signals are being received, and that the motor be started automatically into operation and be maintained in operation under control of the received facsimile signals. For this purpose, there is connected in series with the windings 8 a, relay winding l3 which controls its pivoted armature H. Armature I4 is provided with two contacts l5, I6. When tube 3 is passing plate current, the armature I4 is maintained against its contact l6. This condition is maintained so long as no signals are being received since as above pointed out the tube 3 passes plate current only during the no signal or On the other hand, when trol resistor 2| is also connected between contact l5 and winding 18, and, if desired, resistors 20, 2|, may be variable. The relay winding I8 controls an armature 2 2 sothat when the wind ing i8 is energized it closes the circuit from the A. C. supply source 23 to the motor M. Consequently, as long as strong or space signals are being received, the winding l8 remains energized and the motor M continues to operate to feed the tape 13. If however, the line L'shouldcease to transmit signals for a predetermined length of time, the armature It breaks the circuit with ting space and mark signals corresponding respectively to two different shade values of elemental areas of a subject matter to be transmitted, a facsimile receiver having a recording web and a recording mechanism therefor, a motor for feeding said web and operating said mechanism, and means to control the starting and stopping of said motor, the last-mentioned means includin a relay for opening and closing the motor circuit, the winding of said relay being energized as long as facsimile signals are being received, means comprising an electrostatic storing device whereby said winding is automatically deenergized a predetermined interval after the cessation of said facsimile signals.

2. A facsimile system according to claim 1 in which the relay is connected in circuit with said electrostatic storing device which consists of a condenser and timing resistor whereby the winding is maintained energized during the reception of space and mark signals.

' i including a motor for feeding said web and operating said mechanism, control circuits for said mechanism including a pair of grid-controlled contact 15 and winding I8 starts to deenergize.

This winding does not immediately deenergize because of the charge on condenser 19. After the said predetermined intervalv however, the winding I8 is sumciently deenergized so that the armature 22 is retracted by its spring 24 to break the motor circuit. Consequently, the tape I2 'is fed in synchronism with the transmitting tape only as long as facsimile signals are being trans mitted.

In order to start the receiving control of the transmitting station, all that is necessary isto transmit for said predetermined interval aspace signal which causes the armature M to close the circuit of relay l8. This usually happens automatically when a printed tape is used at the transmitter because when the tape is scanned transversely of its width there is in most cases a white margin between the printing and the edge of the tape. The scanning and transmission of this margin supplies the necessary signal condition to start motor M. Motor M once started is maintained in operation thereafter by the continued receipt of space signals even though alternated by intervening mark signals because of the relatively slow time constant of the discharging circuit of condenser l9. Thus the motor M remains in operation during the receipt of facsimile signals. Upon the cessation of facsimile transmission from transmitter l,

the winding l8 starts to deenergize and after a predetermined interval it causes the motor circuit to be opened.

Various changes and modifications may be made herein without departing from the spirit and scope of the invention.

What I claim is:

1. In a telefacsimile transmission and receiving system, a facsimile transmitter for transmitmotor under tubes one of which is normally conductive and the'other normally substantially non-conductive,

said tubesremaining in thatcondition' as long as one of said kind of signals is being received, e. g., a marking signal, means responsive to the reception of the other kind ofsignal, e. g., spacing, for reversing the conductivity state of said tubes, a relay for controlling thecircuit of said motor, said relay beingen'ergized when said other kind of signal, e. g., spacing is being' received, and means to maintain said relay energized for a predetermined time interval after the cessation of receipt of said other kind of signal, e. g., spacing.

4. In a telefacsimile transmitting and receiving system, a facsimile transmitter having means to generate afacsirnile signal current of large amplitude'ccrres'ponding to one range of shade of the subjectmatterbeing scanned, e. g., white, and generating a small amplitude facsimile sig nal current corresponding to a different range of shade of said subject matten'e. g., black, a facsimile receiver having a recording tape and recording mechanism responsive to said signals to reproduce said black and white shades on said tape, a motor for operating said mechanism and feeding said tape, a pair of grid-controlled tubes selectively responsive to said black and white signals, a relay controlled by the output current of the one of said tubes means whereby said relay is selectively responsive to the reception of white last-mentioned means including a relay for open- Q ing andclosing the motor circuit, a condenser connected in circuit with said relay said condenser being charged by one class of received signal, e. g., spacing, and maintaining said relay energized for a predetermined time interval after the cessation of said space signals, said condenser being connected to said signal receiving circuit.

so as to be charged by the spacing signals.

AUSTIN G. COOLEY.

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