US2151936A - Character transmitting system - Google Patents

Description

March 28, 1939. Hi PFLUGNER ET AL 2,151,936

CHARACTER TRANSMITTING SYSTEM Filed Oct. 31, 1956f mil! .HHi

by A'ZZorney Patented Mar. 28, 1939 uNl'lE' sm'rss insists PATENT orrics 2,151,936 ommwmn museums srs'rsne company Application October 31, 1936, Serial No. 108,576

In Germany October 31, 1935 1 Claim.

It is well known to transmit characters by resolving each character into dots which are transmitted from a sending station to a receiving station with the aid of the methods used in picture telezraphy. It is also known to make up the transmitting apparatus after the manner of a typewriter and to send the component parts of the respective character with the aid of storing means in the shape of discs provided with conductive segments or conductive foils or cam discs operating contacts or the like, suchdiscs being moved in combinations according to -the charactor to be transmitted, as is the case with the so-called picture writers.

: Further it is known to dispense with special apparatus for synchronizing. To such end each signal that is sent is at the receiving station several times written down on the recording tape.

Hereby it is attained that in the case of a departure from synchronism at least one of the character lines recorded at the receiving station shall be complete, i. e. readable. This method however has the disadvantage that the record lines are more or less oblique on the paper tape, in accordance with the degree of the departure from synchronism. This method is nevertheless sufiicient in. many cases, and it is so especially if the transmitted telegrams are only intended for a small circle of persons who have daily or frequently to do with these telegrams. If however the telegrams are intended for the general public then a recording of this nature is frequently annoying, as it requires a certain skill in order to read them quickly.

The invention therefore has for its object to record the characters only once and to employ a synchronizing method which shall be as simple as possible and by which on the one hand the time required for transmission will not or will only slightly be increased, while on the other hand the expenditure in apparatus on the receiving side shall be as small as possible. For this purpose the synchronizing impulses are given in the pauses between the picture lines which serve to compose the characters, and they are also caused to clutch the writing device to the continuously running motes, the writing device remaining in this condition during one revolutlon.

panylng drawing in which.

- Fig. i is a diagram illustrating the method employed in connection with the novel arrangegg merit. Fig. 2 is a partially diagrammatic per- The invention is'described hereafter by way fol example, reference being had to the accom-' spective view showing one embodiment of this arrangement. Fig. 3 is an elevation showing a modification of the arrangement representedin Fig. 2. Fig. 4 is an end view to Fig. 3. I

In Fig. 1 a receiving tape l and some charac ters A, B, C, D thereon are represented. On tape l, for each picture line 2 extending transversely of the tape, a short synchronizing impulse 3, given at the commencement of the picture line, is marked as a dot. In the case represented by way of example, the characters are reproduced with the aid of seven picture lines each. In the pauses between the characters no synchronizae tion isfleifected because it is not necessary to synchronize here.

For the sake of simplicity, only those parts of the picture writer are represented in Figs. 2, 3, 4 which are concerned with the invention, other parts not being shown as they are not necessary for a complete understanding of the invention.

The writing device represented in Figs. 2, 3, 4 has a so-called Meyer edge C and a counter edge S adapted to cooperate therewith in order to record the impulses in a well known manner.

On a cylinder or barrel B the edge C is arranged as a helical crest. Barrel B is mounted loosely on the shaft A of the motor M. Coiled around shaft A is a helical spring F one end of which is fixed to barrel B in the manner, for instance, appearing from Figs. 3 and 4. This spring tends to contract in order to come in fric- Ill tional contact with shalt A and has a free end.

adapted to be engaged by a tooth or stop n. If so engaged, spring F is out of frictional contact with shaft A. This state of things is represented in all the three Figs. 2, 3, 4. I

Edge S isjointedly connected with a lever K fulcrumed at e. Lever K is the armature of an electromagnet Q and is under the action of a retractile spring E.

The constructional features as thus far described are peculiar to both the arrangement shown in Fig.2 and that shown in Figs. 3 and 4. The difierences between the two are as follows:

- In the arrangement acording to Fig. 2, stop n forms part of a lever H fulcrumed at d. This lever is the armature of an electromagnet R and is attached to a retractile spring D.

In the arrangement illustrated in Figs. 3 and i, stop 12 forms part of a leaf spring I mounted at g. Spring carries a tappet a that projects into the path of the edge S but does not extend beyond edge C, being spaced at about 0.1 millimetre, or nearly so, from the circumference thereof. Edge 0 has a recess b.

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The mode of action is as follows:

In the arrangement shown in Fig. 2, each synchronizing impulse, given at the commencement of a picture line, energizes magnet R which then attracts lever H. Hereby the free end of the spring F is released. This spring in its eifort to contract comes in frictional contact with the rotating shaft A and thus acts to clutch the barrel B to this shaft. The device B, C is hence caused to share in the rotation of shaft A until the free end of the spring F comes against tooth n, lever H having been restored to. normal by spring D after the cessation of the synchronizing impulse. By the free end of spring F striking the tooth n, this spring is expanded so as to release shaft A. The device B, C therefore ceases to rotate, having performed one revolution in this way.

Magnet Q. Fig. 2, is energized by the picture impulses. and by means of lever K and spring E causes the edge 5 to be pressed against edge C in the rhythm of these impulses.

As the arrangement shown in Fig. 2 has two magnets. namely, magnet R for the synchronizing impulses and magnet Q for the picture impulses, there must be a switching device for changing from one magnet to the other. An arrangement of cam discs or any other suitable device may serve this purpose.

Such additional control means is superseded in the arrangement shown in Figs. 3 and 4, magnet Q here being arranged to receive both synchronizing and picture impulses.

Each impulse acting on magnet Q, Fig. 4, will by means of lever H and spring D actuate the edge 5 in the manner described with reference to Fig. 2. When a synchronizing impulse arrives the position of the barrel B and edge C is that represented in Figs. 3 and 4. As a result edge 3 is allowed by recess b to strike the tappet a so as to depress the spring momentarily. Tooth 1: therefore releases the free end of the spring F which then acts to clutch the device 8, C to the rotating shaft A, as described with reference to Fig. 2. Since owing to recess b edge 8 does not yet come against edge C, the synchronizing impulse is not recorded on the paper tape P which for the sake of dmplicity is shown in Fig. 3 only. The picture impulses however now arriving cause the edge 8 to be pressed against the rotating edge C, as described. After bne revolution made by device B; C the spring F is again caught by tooth n and the rotation of B, C thus stopped. It is necessary to such end that after this revolution the spring I does not vibrate any longer, because otherwise the free end of the spring F may happen not to be arrested by tooth n and thus cause a picture line to be out of phase.

In the arrangement according to Figs. 3 and 4 the synchronizing impulse, given at-the beginning of each picture line. is not delivered separately from the picture impulse but is given in conjunction therewith, without however being. recorded. The fact that the synchronizing impulse is not recorded is due to recess b, as described before. Paper tape P is during the recording moved continuously, this being contrary to the start stop writers. The advantage of the n vel arrangement resides in the fact that the device can be made to occupy a comparatively small space while being simple in mechanical and electrical relation. If the synchronizing impulse happens to be indistinct or even suppressed, then only a phase displacement of a picture line will occur without the entire picture being less easy to read, because whenever a synchronizing impulse is missing, the first picture sign will instead actuate the described clutch or a clutch of a suitable other construction.

What is claimed is:

A recording for recording characters composed of a plurality of electric impulses which when recorded form the separate characters, comprising a transcribing means including a shaft, 9. cylinder provided with a helical edge rotatably mounted on said shaft, a motor for continuously rotating said shaft, a spring clutch including a helical spring wound around said shaft and having a free projecting end for coupling said cylinder to said shaft, means including a detent engaging the free end of said spring and tending to force it in a direction opposite to the winding of the spring for holding said clutch out of engagement with said shaft inthe absence of signals, and means responsive to receipt of a synchronizing impulse to eifect engagement of said clutch with said shaft.

HELMUT PFL'UGNER. ERNST sons.

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