US1759303A - Method and means for the transmission of pictures and the like - Google Patents

Description

7 May 20, 1930. FULTON 1,759,303

METHOD AND MEANS FOR THE TRANSMISSION OF PICTURES AND THE LIKE Filed April 19, 1928 2 Sheets-Sheet 1 Lair-n 1, 5/7110/5 Ina/liar 077/0 F TO/Y May 20, 1930. FULTON 1,759,303

METHOD AND MEANS FOR THE TRANSMISSION OF PICTURES AND THE LIKE Filed April 19, 1928 2 Sheets- Sheet 2 ILyr M M;

all]! ,3 V W J M J menfor Arrow amongothers, improvements of the recordingfand manipulating contrivances of long 7 latented May 20, 1930.

PATENT ornca omo FULTON, or BROMLEY, ENGLAND IIETHOD AND MEANS FOR THE TRANSMISSION OF PICTURES AND THE LIKE Application filed April 19, 1928, Serial No. 271,296, and in Austria April 12, 1927.

This invention relates to, improvements in and connected with methods of and means for the long distance transmission of pictures, diagrams and other impressions.

Various methods and apparatus for transmitting long distance light images and gen- 7 eral television have already been devised,

these being provided with a rotating drum and a writing contrivance shifting trans- 10 versely of the drum. The various systems known consist of a rail, adjusted in parallel with and alongside of the drum axis, for carrying the traveling recording pin or feelmg device which is connected compulsorily with the driving shaft of the drum by means of a suitable traverse. 'With some systems a screwed spindle efiecting the longitudinalmovement either of the recording pin, or of the cylinder, is connected with an extension of the cylinder, so as to simplify the construction and to increase the reliability of the apparatus. These systems need an arrangement for producing synchronism between the transmitter and the receiver. It is further knownthat in various modes of long with these known methods to employ. syn;

chronizing arrangements including 'a relay at'the receiving end which is put inaction by I {he transmitter at the conclusion of a picture -,1ne.- v

; Important features ofthis invention are "distancetransmitting apparatus, an a comibinationiof these modified. mechanisms with $9; a system ofsynchro'niz'ation using a relay con- --n ected' with the telephoto'graphy or plcture circuit. I 'Anotherfeatureof th'iS f invention is an improvement'jof the arrangement for moving the stylusf'vor other such device in relation to the drum in {the direction of its. axis. Us- --uallythe ycylinder and thefs'pin'dle have a I common-axis, and" the stylus is carried on a i I I "spiraliscanning of, the transmitter "011 or}? film, su itab1 -y=' prepared and stretchedon a r carriage supported-on rollers, this -'carriage f alsocarryingawheel with a'kjnife-edge to en'- gage the screw-threaded spindle. Should the spindle continue rotating, while the apparatus is .irl operation, after the stylus has reached the proper end of its travel, the. mechanism may be damaged. To prevent this, this invention provides that the part of the mechanism interacting with the screwthreaded spindle, rides near the end of its travel, on to a body conveniently shaped, ro-

half tone photographs. For purposes of an electrochemical writin process it is of special advantage to divi e up the pictures, diagrams and other impressions to be transmitted by means of linear screen, in which case the scanning is effected in a normal ratio to the lines of the screen. By this method alone, which avoids the disadvantages of a modulation of intensity, it is possible to produce half-tints equal in quality to those obtained by optical means. These half-tints, when usedas clichs, look equally nice in print. The combined use of. such images that V have been divided up in lines, in connection with a synchronizationmethod with a relay rent between transmitter and receiver, for the purpose ofimproving the quality of the pictures transmitted, are further points of and the measure to specially regulate the curinterest of this invention. It is of vital prac tical importance that the same apparatus should be used for transmitting and receiving, which has until now not been done with the system workingwith a relay.

- As [above-explained, 'in prac screen is usedi'which, in the case-of the usual.

tice' a line drum, is passed under the stylus effecting the scannin at right angles to the screen lines. When t e stylus slides transversely over the screen lines,.it will first touch the bare con- 3. ducting surface of the picture support, and

then again the insulating line; according to the different width of the screen lines, that is to sav according to the degree of light of the corresponding picture portions, the .successive current impulses will be therefore longer or shorter, and will act accordingly at the receiving end. The number of the picture elements to be transmitted, that is to say the fineness of the screen used, is dependent on the advance or feedof the stylus, that is to say on the pitch of the screw-threaded spindle used for the purpose. If the number of threads per unitof length is. increased, all other conditions remaining equal, there will 2Q take place a considerable lengthening of .the

time of transmission, so that for that reason, in order to enable optimum time of transmission to be maintained for-the same size of picture, the wealth of detail of the pictures 25 to be transmitted cannot be raised beyond a certain measure.

To sum up, the advantage is ensured that in the case of half tone pictures and drawings, more detail can be obtained without in- 30 creasing the time bf transmission, as well as the possibility of transmitting thinner lines arallel to the direction of scanning. It must he further mentioned that the use and application of this stylus to other apparatus, also 35 comes within the range of the present invention.

The synchronizing arrangement employed in the above described modified apparatus for lon distance transmission is now to be descri ed.

In the method with which this invention is concerned, the transmitting apparatus is op-' maining inaction. With this arrangement it is unavoidable that, by the changes of strain resulting from the arresting of the receiving apparatus, some disparity should occur. es ecially if inexpensive and not very power ul driving motors are employed.

s To achieve good results even when using light motors, it will be suflicient to stop the sear' ner device of the transmitter in the same way. as in the receiver, the relay releasing the sto ping or locking device at the receiver en and thus insuring equable characteristic of movement (snychronization) during the time of one period of utilization, if the apparatus at the transmitter and at the receiver are simultaneously started and are driven by motors of equal power. The couplings used between the motor and the feeler or scanning device should also run equally.

By this method synchronization is greatly perfected, and a far more uniform movement in the intervals between the phases of rest is attained. The advantage of this system also is, that by the uncoupling of the relay of the It is known that the mechanical couplings for connecting the motor to the drum are mostly made in the form of slipping friction couplings which have the drawback that the driving motors are braked when the drum is .stopped and therefore, in order to avoid acceleration when the drum is released, the motor has to be made as powerful as possible. If on the other hand in order to avoid excessive braking the coupling is adjusted so that its action is not powerful enough, the driving of the rotating drum does not take place at once, and the whole Working for the purpose of synchronization is jeopardized. Moreover,'it is difficult to construct such couplings mechanically in such a .manner that their. action always remains the same and that they do not require any adjustment or attention for a long time.-

For avoiding this last fault, it is further known to use electromagnetic couplings which can be used exactly like friction couplings, but owing to the elimination of theparts subect to wear and to the possibility of varying the electric current energizing them, their action can be easily modified and maintained constant.

The drawback of these arrangements is that they consume too much energy for their operation, as in the absence of parts rubbing against each other the torque has to be transmitted through an air gap, and further that, as alread stated, there takes place a braking of the riving motor when the drum is stopped, that is to say, in the operation of the coupling.

The invention solves the problem of improvement of such couplings used in the pic ture transmission apparatus, in such manner that, all the above mentioned drawbacks are eliminated, that is to say the driving motor is no longer braked, .and on the other hand, whilst avoiding as far as possible expensive constructional elements, great constancy with even veryweak and therefore cheap driving motors, for instance spring mechanisms, can

he used, provided only that they possess a sufficient degree of uniformity.

Another advantage over any friction couplings is that there cannot be possibly any dependence on the material of any friction covering, that consequently complete uniformity of action at any point of the circumference is guaranteed, that no wear can take place and therefore, even after a long period of working, no adjustment or generally any setting becomes necessary.

According to the invention a magnetic coupling is utilized in such manner that it acts as a rigid coupling only when the transmission of a torque is desired ;:in the other case however, that is to say during the time of locking of the writing device, the coupling is completely disconnected so that the driving gear does not have to perform any frictional work. At the moment when the locking device is released, the coupling is also automatically operated again, namely, in such a manner that the parts to be driven, are at once put in motion, without risk of any slipping. The necessary instantaneous forces of acceleration are also supplied by a weak driving motor, provided that the constructional elements to be driven are correctly proportioned.-

' ment in such a process of synchronization is- It is known to employ in apparatus for distance transmission of pictures, methods of synchronization in which at given time intervals,for instance after each revolution of the cylinder carrying the transmitter film or foil, 2. current impulse or, in the case of wireless transmission, a train of waves is sent from the transmitter, which is used for the 'syn cl'ironization in the receiver, in such a manner that by means of a relay a stopping or locking device is released, so that both transmitting and receiving apparatus begin a new revolution synchronouslv. It is also known to use for this purpose slip rings rotating with the transmitter cylinder and provided with the suitable contact segments, or polished strips of suitable width transversely over the whole iuipably prepared metal transmitter filmor o1. I According to the invention, an improveobtained' by transferring the metal contact extending throughout the-whole width of the transmitter cylinder, so that it constitutes the devicewhich is'used for mechanically securing or fixing the transmitter foil to the cylinder. This ensures that the space otherwise 7 used for the securing or fixing device, will not be'lost for the picture surface, and onthe other hand that the transmitter foil will-not 'havetof be provided in any extra way with a synchronizing strip, and that the bright,

contact strip could bemade very accurately and of sufficient mechanical strength. A suit- As alreadystated, on the receiver there is used a relay which is operated by the incoming current impulse and thereby produces synchronization in any desired-manner by makinga suitable contact, for instance, for the release of a locking device for writing drum of the receiver.

' It is known thatfor that purpose polarized relays are used which are arrangedin the pic-, ture circuit of the receiver and so connected bymeans of a suitable slip ring provided with segments, that the direction of the synchronization impulse is such that the armature or keeper of the relay is turned over and effects the desired contact.

According to the invention, an improvement is effected in such an arrangementby making the connection, when using relays, in such a manner that the relay. is normally short circuited, and is switched into the picture circuit only immediately before the incoming current'impulse. This ensures that the resistance and the inductivity of the sen- ,sitive, and therefore mostly high ohmic relaysynchronization on account of atmospheric" disturbances in-the case ofwireless transmis sion is greatly reduced, and moreover in the event of any getting out of step during a period of synchronization, phase coincidence will be obtained again in a reliable manner. .at the next period. Y

It is preferable to combine all the spring contacts in a: single group, namely all those which are used for the. sending of the synchronization impulse, for the short circuiting of the relay and further also all the switches used say in magnetic couplings. With a proper construction, practically allof them I can be controlledby. means of one projec'tion or cam, and therefore,'in addition to a-greater simplicity, a subst'antiallygreater. reliability of working will be ensured. J:

J 1In order; to enable the Invention readily understood, reference is made toithe accompanying drawings, which illustrate from endwise movement.

only releases the receiving drum with the asdiagrammatically and by way of example, suitable arrangements for the carrying out of these improvements, in which drawings F ig. 1 is a plan view somewhat diagrammatic of one form of scanning and recording device;-

Fig. 2 is a diagram illustrating the electrical connections of the recording device shown in Fig. 1;

Fig. 3 is a diagram illustrating the electrical connections for the magnetic clutch, and mechanism actuated by the synchronizin" signal;

Fig. 4 is a side View of the stop mechanism; and

Fig. 5 is a plan view of the stop mechanism.

Figure 1 shows one mode of construction of the scanning and of the recording appliances. S is a spindle mounted in the bear Zngs L, and L,, the drum Z bearing'the recording surface, being coaxial and joined therewith. The spindle and drum arerestrained The stylus P is mounted on a carriage \V to be movable par- 1 allel with the drum Z. The carriage carries wheel R, which engages in the threads or grooves of the spindle. If the whole arrange- 'anent W moves from the right to the left, the

wheel R moves into a continuation ofthe thread formed in the cone K, and thus rises and lifts the stylus-P ofi the cylinder Z. In the place of its greatest dimension the cone K has a rut, in which the wheel B'- is retained, even ifthe spindle S. continues rotat It constructional example of the synchronizing arrangementas employed with the'improved apparatus is schematically shown in- Figure 2. The picture current, strengthened for xample by means of the three element vvacum tube V,passes through the relay R and the recording surface Z, here formed as a drum with the recording or feeler pin S. The

relay R works a contact K which closes a local battery circuit for removing a stop H and thus releasing the drum.- The relay R is mechanically so inert, or electrically so retarded, that, even while transmitting half-tints which ought to be dividedup into their s'eparate'elements by means of a suitable screen, it permanently remains attracted and consequently sistance of contact K if, at the same moment, the scanning device at the transmitting end, starts a new picture line.

Figure 3 schematically shows one mode of construction of electromagnetic coupling for obtaining better synchromzation.

On. the spindle A is mounted the magnet, M with its armature A,. In practice the magv net M is made preferably in the form ofa flat pet magnet, and the'armature A, in the form of a disc arranged opposite it and prevented from rotating an the spindle by a tappet N.

.One end of the winding of the magnet. M is the circuit leading from the battery C- through a group of spring-contacts, controlled by suitable cams or the. like, and

through the ring S and the winding ofthe magnet M, so that the magnet M will attract and hold fast the armature A... The magnet M and the ring S are mounted on one and the same sleeve which is loosely rotatable on the spindle A which at the same-time also carries the gear wheel D effecting the driving, so that at the moment when the magnet M is energized by current, the armature A and owing to the tappet or driver N, also'the spindle A and all the parts secured to it, will begin to rotate. The ring S which is con stantly connected with the body, is provided at a single point with an insulating part I which, in the position of rest; that is to say when the stop H engages with the armature B, is situated under the brush E. During the remainder of the revolution, the contact K is short circuited through the brush E and the ring S so that the coupling always remains operative, even when the relay R and therefore, through the magnet M the armature B, and the contact K are not operated.

The operation is as follows:

In .thejposition of restwhen the cou ling I is disconnected, the driving motor whic engages wlth the gear wheel D, will have to overcome only the very slight friction caused on the spindle A by the magnet M, ring S1 and gear wheel D, as the armature A rests on the magnet M without the slightest pressure. If the relay R is switched in for a short mensioning is correct, that even a short sliding of the armature A on the-magnet M is made impossible. All the parts will now participate in the rotationuntil the current is cut off fromthe magnet M, which takes place at the moment when the brush E or alternative.

spring-contacts reach the insulating part I." This takes place immediately before the completio of a full revolution and before the stop "touches again the armature B. If

' the magnet M and the armature A are made ,of a suitable material, the forces between the two parts will cease to act at the moment when respectively.

the current is cut off. The same thing will then take place again as described.

It cannot therefore happen in such an arrangement according to the invention that the two coupling halves will slip on each other, that is to say the driving motor will always have to work under a practically constant load; whether the parts connected to the spindle A be driven or not. Moreover the great forces produced, ensure that no material slipping of the coupling will take place, so that the greatest part of the faults otherwise occurring in such apparatus used for picture transmission, are avoided, and the l quality of synchronization is improved accordingly. h

A further improvement in this apparatus relates to the locking device.

Since at the moment of locking of the re-' lating parts they are no longer acted upon byany torque, that is to say the electro-magnetic coupling was disconnected a short time before, and the last short fraction of the revolution is completed freely under the ac- :5 tion of momentum, it will happen as a rule that on contact with the stop, the rotatable parts will be thrown back, and( therefore the stopped rotating parts do. not always begin their new revolution from the exactly defined position of the projection or the like utilized for the stopping. It is therefore necessary to provide for the construction of coupling according to the invention, also a new locking device, namely so that at the moment of stopping, all the rotating parts should be coincidently and completely locked, so that the new revolution shall always start from the exact defined position.

. A construction of the apparatus. according 40 to this part of the invention is diagrammatically illustrated by way of example in Figures 4 and 5, in elevation and in side-view To the rotatable arts of the apparatus is connected the disc which is provided at one point with a recess P into which fits thecorrespondingly shaped projection N This projection is secured to the armature B which is mounted for instance on a spring F; in front of the armature, is arranged the magnet M which eflects the release in accordance with the preceding description of the coupling. Owing to the projection N sspringing into the recess P and being lifted out only at a suitable moment bythe magnet M a complete locking of'the rotating parts .is' ensured, independently of-any inertiaan'd elastic rebound forces that may occur.-

The hereinbefore described modificationand 'apparatus represent in their combination a considerable advance in the longjdistance transmission of light images and general television. Measures to combine some,

several'f'or all of these innovations with a1 05 readyeitistingapparatugmight prove mostadvantageous and such combinations certainly are within the scope of this invention.

What I claim and desire to secure by Letters Patent of the United States is 2- .1. A device for the electrical reception of pictures, comprising means for receiving both picture signals and synchronizing signal, a rotating receiving drum, and drlving means therefor, an electromagnetic clutch which is electrically energized to couple the receiving drum'to the driving means, means for stopping the receiving drum at the completion of each revolution, means operated by the synchronizing signal for releasin the receiving drum at the commencement 0 each revolution and for energizing the said clutch, other means for maintaining the clutch electrically energized throughout substantially the remainder of the revolution while the picture signals are being received and means operated by the picture signals for receiving a picture.

2. A device for the electrical reception of pictures, comprising means for receiving both the picture signals and the synchronizing signal, a rotating receiving drum and driving means therefor, an electric magnetic clutch for coupling the receiving drum to the driving means, an electric magnetic device comprising a movable armature constituting a stop for the receiving drum at the com'pletion'of each revolution, means for energizing said electromagnetic device to withdraw the stop and release the receiving drum at the commencement of each revolution, electric contacts operated by the movement of the armature in releasing the drum to close the energizing circuit of the electromagnetic clutch, other means for maintaining said cir-' cuit closed during substantially the remainder of the revolution of the drum, and means operated by the p'icture signals for reproducing a picture.

' 3. Apparatus according to claim 1 where;

in the electromagnetic clutch is maintain energized after the synchronizing signal has ceased by means of a circuit in parallel with the aforesaid electric contacts and including an automatically operated switch for opening this circuit immediately before the drum completes a full revolution.

4. Receiving apparatus for transmitted pictures comprising a rotatable drum, means cooperatin with't edrum to reproducethe transmitte picture, drivin means for the between. the drum and the driving means, a

a synchromzin signal, a switch also operated' by the sa1d electromagnetic device for closing an energizing circuit of the clutch,

'and'switch contact means operated by the rotation of the formaintaining the 'drum, an electromagnetic, c utch interposedclutch energized during substantially the remainder of a revolution after the synchronizing signal has ceased.

5. A device for the electrical reception of pictures, com rising a drum for holding a sensitized bo y, a stylus coacting with the sensitized body, a continuously rotated element, an electrical clutchbetween the continuously rotated element and the drum in- 10 cluded in an electrical circuit, means for stopping the drum at the conclusion of each revo-' lution, electrically actuated means for removing the stop, means for momentarily closing the circuit through the clutch when the stop is removed, other means for closing said circuit through the clutch responsive to the setting of the drum in motion, and means for opening said last mentioned circuit-closing means, responm've to the completion of the revolution of the drum.

6. A device for the electrical reception of pictures, comprising a drum for holding a sensitized body, a stylus coacting with the sensitized body, a continuously rotated element, an electricaloclu'tch between the continuously rotated lement'and the drum included in an electrical circuit, means for stop.-

ping the drum at the conclusion of each revolution, electrically actuated means for remov- 39 ing the stop, a switch in said circuit,means for closing the switch when the stop is removed, a second switch, in said circuit in multiple with the first switch, means for closing the second switch, responsive to the setting of the drum in motion, and means for opening the second switch, res onsive to the completion of the revolution 0 the drum.

' In testimony whereof I have signed my name to this specification.

4o OTHO FULTON.

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