US2140596A - Method and arrangement for synchronizing of printing telegraphs - Google Patents

Description

1938 HJRASSOVQ, 2,140,596

METHOD AND ARIMHG'EIMEN' I I'YJR SYNCHRONIZINGV OE PRINTING TELEGRAPHS Fi led Dec. 7, 1934 2 Sheets- Sheet 1 Jib sTWAss n If is 9 ATToR/vs K's rinsed as 20, 1938 U D STATES-PATENT OFF-ICE.

GEMINI. FOB

MN I SYNGHBONIZING F PRINTING TELE- amiss Horst Rassow, Berlinassignor to Siemens &

Frledenan, Germany, Hslske, Aktiengeseilschaft, Siemensstadt, near Berlin, Germy, a corporation of Germany Application December '1, m4, No. 150,390 V In Germany December 11, 1933 -or. .picture line's and are transmitted by'corresponding impulse sequences. An object of the invention is the provision in a facsimile telegraph system of a simple, reliable,

,and' efllcient instrumentality for eifecting syn;

chronization.

The above, and other objects of the invention are achieved by the provision of a facsimile receiver arranged with a power-driven spiral prints i5 'ing edge which carries a stop 'arm arranged to be nsaged once for each revolution by a stop member moved in the path of the stop arm under the control of a signal-responsive-magnet which is deenergized intermediate eachseries-of symbol- 1 go representing impulses and which is reenergized from the transmitter at the beginning of the next series of symbol-representing impulses'for h allowing an'additional cycle of the printing edge.

' Synchronizationof the apparatus is accordingly accomplished. in v Reference isto be had tothe accompanying drawings, in which Fig. 1' is a diagrammatic view showing how, for transmission purposes, the letter --U is'v-analyzed or scanned according to a system in which the field is subdivided into. twelve par allelstrips' or lines; Fig. la is a face view of a cam disc controlling the transmission of said letter'; Fig, 2 is a perspective view showing a portion oi.' the transmitter; Fig. 3 is a perspective view 5 showing a portion of the receiver; Figs. 1, 1a, 2,

and 3-are merely illustrative of the type of printing telegraph to which my invention relates; Fig.

4 is a plan view, and Fig. 5 is a side elevation, of

a printing telegraph receiver embodying my in- 40 vention.

I .Fig. 1

Fig. 1a shows a. disk 3 with portions 2 forming cams-located at a; greater distance from the center than the intervening portions 2', the several' portions 2, 2 being of proper circumferential extent to operate a suitable circuit-closer.

' upon rotation of the cam disk, in such a manner that the periods of current impulses and oi interruptions will correspond respectively to the black and the white portions or the letter U shown in Fig. 1. The shortest cam disk portions or intervals 2, 2' (current or no current respectively) occupy xiooth vof the length of the circumference of the cam disc 3 which serves to transmit. the

shows how for instance the letter U is analyzed with the aid of twelve individual lines l.

' Thccams 5 differ as to the arrangement of their (cans-sat) letter and the necessary space. After the transmission of the signal impulses required to transmit the particular letter there follows a no-current interval of at least %th of the circumference ofthe disc.

' Fig. 2 shows a diagrammatic representation of a keyboard sender. On a shaft 4 which makes five revolutions per second, are arranged 48 cam discs I for the transmission of figures and letters. teeth 6, such arrangement corresponding to the 10 picture analysis ota letter, figure, or other Si n.

. The .problem now to be solved is to couple the keyboard 01' the sender to these discs so that at every revolution, only the picture signalof one letter is eflective. To attain this a keyboard lock must be arranged so that when a key is operated, the remaining keys are locked. Only ,during the quarter revolution, "while the space between two letters is being transmitted, are the keys unlocked. If, in this time interval, the key L, for e I ple,is operated-an insulated distance-piece 'l' ited to such 'a position that the contact springs ad.- iaoent thereto are opened and closed-in accordance with the cams on the disc corresponding to the letter L. All other contact springs remain in the open condition, since their. distance pieces are in the normal position under the action of thekey lever springs-2.

The signals are sent by' audible frequency alternating current so that they may easily be transmitted over any keying lines to the radio transmitter and on the other hand, to take advantage of the telephone links generally employed. The carrier frequency is 900 cycles. I,

The principle of operation of the receiver is shown in Fig. 3.

The essential part of the receiver is a printing spiral formed on a small roller running at revolutions per second. Contact between the printing spiral 8 and the paper band or tape 9, at a speed-of five letters per second, occurs twelve times from the top to the bottom and prints a line. In order to obtain immediate, visible, impression on the paper, this is covered with a thin carbon paper of the same width, which for clarity is omitted from the diagram. If the receiver is energized by a current, the receiving magnet it.

attracts its armature II. This presses a rounded edge or platen l2 from underneath and against the paper tape I so that a line is recorded if the magnet l0 remains energized for the entire duration of the transmission ofa line. At the next revolution the paper tape is stepped iorward by the paper feed device it so that the next occurs close to the first.

,In Fig. 3 the printing spiral I is duplicated on therolier so that the letter picture is recorded simultaneously in two parallel lines. The purpose 01' this double record is to secure a synchronizing arrangement. The lines of print are accurately parallel only if the number of revolutions of the print spiral 8 is in exact accordance with the transmission time of the picture lines. It these speeds difler from one another the length of the ceiver after each line, corresponding to the scanpicture lines are not parallel to the paper strip but run upwards or downwards.

The above described well-known telegraph apparatus obviates errors due to an inaccurate phase relationship of the transmitter and thereceiver, by producing a double record of the letters in two parallel lines,so that at least one of the duplicate letters is recorded readably. But this particular in wireless transmissions.

In accordance with the invention thesedisadvantages are overcome by an arrangement which in accordance with transmitted synchronization impulses momentarily checks, that is, arrests or brakes the rotating printing member or wheel after the recording oi each line, in which the received letters, or other symbols are analyzed.

The rotating transmitter device includes means to transmit synchronization impulses for momentarily arresting the printing member on the rening of the letters or other symbols. It is useful by the fact that the stopping of the printing member is efl'ected by a spacing signal after each line corresponding to a scanning oil the letter signals, because in wireless transmission the adjustment can not be eflected by a marking signal, since static can effect a stopping of the printing member. I

It is also necessary that the adjustment of the phase relationship be controlled by a spacing signal in continuation of a marking signal.

It is advantageous to efl'ect the stopping of the printing member electrically or mechanically by the receiving magnet system for the direct adjustment by the receiving magnet system. a stop being arranged on the armature of receiving magnet system to arrest the printing member. It is also possible to effect the stopping by a circuit for regulating the driving motor oi? the member.

printing member which is controlled by a contact of the armature oi the receiving magnet system and a second contact which-is closed independently of the phase relationships 01' the printing In Figs. 4 and 5 of the accompanying drawings the invention is' illustrated in one example of construction. 7

The motor 1 of the receiver runs a little faster than the transmitter and drives by the friction clutch 2 the printing member 3. Underneath the printing member 3 is arranged a carbon paper 5 and the paper tape 4, which are pressed against the printing member by the edge 6 of the springretracted armature I when the magnet 8 is ener-.

gized. The recording of the letters, figures and other symbolsis eiiected in the same manner as described and shown in Fig. v3 by the co-operation oi. the platen-forming edge 6 of the armature with the printing member. Every letter is analyzed in lines which are nearly perpendicular to the direction of the movement of the recordingpaper. On the printing member 3 is arranged a stop 9, which after the scanning of one line, in

this case, after one revolution of the printing member, comes against a latch I 0 on the armature of the receiving magnet and the printing member is thus stopped. By a subsequent impulse the armature l is attracted, thus releasing the printing member for another revolution.

The paper feed is eflected continuously by the rollers i I and i2.

I claim: 1. In a printing telegraph apparatus, a transmitter having means to send a series of electrical signal impulses constituting elements which collectively represent a scanning line of a symbol I and to transmit synchronizing impulses intermediate successive series of line-representing impulses which are elements in the transmission of the same symbol, in combination with a receiver having a rotary printing and synchronizing mem' her, and a single signal-responsive member responsive to all of said printing and said synchronizing impulses and cooperating with said rotary printing and synchronizing member to print or to synchronize alternatively.

2. In a facsimile receiver, a single-line rotary printing member effecting printing of a single scanning line at each revolution, a start-stop element on said rotary printing member, a signalresponsive printing member, a further start-stop element on said signal-responsive printing element, said start-stop member and said further start-stop element engageable together at each revolution of said rotary printing member in response to a received synchronizing signal to stop said rotary printing member after effecting printing of eachscanning line for synchronizing.

HORST RASSOW.

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