US2657260A - Apparatus for the transmission of current pulse combinations, particularly for teletyping - Google Patents

Description

Oct. 27, 1953 o. MOSER 2,657,260

APPARATUS FOR THE TRANSMISSION OF CURRENT PULSE COMBINATIONS, PARTICULARLY FOR TELETYPING Filed Dec. 10, 1952 Patented Get. 27, 1953 APPARATUS FQR THE TRANSMISSION ()F CURRENT PULSE COMBINATIONS, PAR- TICULARLY FOR .TELETYPING Otto Moser, Bern, Switzerland A plication December, 10, 1952, SerialNo. 325 ,163 In Switzerland December 14, 1951 '7 Claims. (Cl. 178-17) My invention relates toapparatus for the transmission of currentpulse combinations, particu-- larly for teletyping.

fS uch apparatus have a group .of selectively actuable setting means, consisting in teletypee writers essentially ofakeyboard with individually operable keys, for selecting a code combination corresponding to the particular message character to betransmitted. -A number of pulse control members and correlated to the respective setting means or keys. The pulse control members may consist of revolvable cam discs that are firmly mounted ona common shaft or on different shafts driven by a motor. The pulse control cams become selectively effective to control an electric contact device .for transmitting to thecornmunication channel. the trains of electric pulses .corresponding to the various code combinations.

It has been proposed'to provide the pulse-controlling cam .discs ,in such apparatus with a lateral cam groove rather than with aperipheral cam configuration, the. lateral cam grooves of the respectiveldiscs being differently shaped in accordance with the particular code combination assigned to each disc. Each cam disc coacts with an individual feeler which is normallyoutside the groove and enters it only when the pertaining setting means or keyis being actuated. The particular. feeler thus placed into cam engagement then acts as a cam follower during one full cam revolution. and is thus caused to oscillate in a rhythm corresponding, to the code combination assigned tov the selected message 'character to be transmitted; and the electric contact device then closes and opens a circuit to issue corresponding electric pulses. An apparatus of this type, in contrast to those operating with a cam contour on the exterior cam periphery, has the advantage of a more reliable operation due to the fact that it eliminates contact-bouncing and reduces contact wear by the constrained guidance of the feelers, thus avoiding the pulse distortions resulting from such trouble. However, the pulse control appa-' ratus with lateral cam grooves as heretofore pro posed incur the drawback of imposing highly exacting .requirementgupon the accuracy of the cams, thus involving considerable manufacturing Although,'in teletypewritersystems, slight de-' fections of .the .pulse combinations are usually corrected in the central or exchange stations, there are cases where the communication channel It is an object of myinvention to provide an apparatus for the transmission of current-pulse combinations that affords within its own mechanism a correction of deficiencies that may be due tojinaccuracies in design or assembly of the pulsecontrol cams.

While the invention is hereinafter described with reference to apparatus in teletypewriters operating basically in the manner explained above, the invention is also applicable to any other devices for the selective transmission'of code combinations in which a mechanical switching member, moving back and forth between two positions under control by a selectively actuated setting means, controls an electric pulse contact in accordance with the particular pulse combination to be issued.

According to my invention, I provide such a transmitting apparatus with two revolvable cam discs which are driven at constant speed during the operating period of the pulse control means. Each cam disc has cam flanks mutually spaced on the cam'periphery in accordancewith the pulse periods of, the pulse combination ,to be issued. Two movable switching levers, engaging the respective cam discs, are moved between active and inactive positions due to the revolution of the cam discs, and thereby change the contact condition of the above-mentioned electric pulse contact, one lever effectinga change in one sense and the other lever in the opposite sense. I

further provide the apparatus with locking means I which, under control by the pulse-wise reciprodoes not pass through such a station. This apadapt them to any parti'cular conditions of {the communication channel.

eating switching member, alternately lock one of the two levers and simultaneously release the other lever, the phasing of the releasing operation being such that each lever, shortly after its release, reaches one of the cam flanks and hence can then move to its active position thus switchingfthe'pulse contact. 7 V

The foregoing 1 and more specific objects and features of my invention will be apparent from the following description of the embodiment exemplified by the drawing, in Which a pulse-com-' binationjtransmitting apparatus for a teletypewriter is schematicallyshown' in a perspective View.

isschematically shownat it. Firmly mounted ona shaft 53 are anumber of pulse control-discs,

one for each key, of-which again only one is illustratedfat M. Like all-others, the disc M is provided-witha lateral cam groove 2'? whose cam contour is designed in accordance with the one pulse combination assigned to the particular pulse control disc. .Eachpulsecontroldisc cooperates with'a 'feeler member designed as, a lever ii which is tiltable about a pivot H and whose free end carriesa feelerzpin 152.. Feelermember ii has a bias in the counterclockwise direction;

also causes a start-stop drive (not shown) for revolving the shaft 53 to be started. During the revolution of the pulse control disc i l, the feeler 'pin 42 is caught and held in the groove 27 until a full revolution of disc hi is completed. During the revolution of the pulse control disc I i, the

feeler member 5i oscillates as its feeler pin fol lows the configuration of the cam groove. An arm 41a of feeler member 4! then causes a mechanical switching member 43 to also oscillate between two end positions in accordance with the pulse combination to be transmitted. The switching member as is pivotally mounted at l2 so that its oscillations occur in a plane parallel to the plane of illustration. The switching member 43 is common to all feeler members of the apparatus.

During the revolution of the pulse control disc I4, another shaft i8 is also revolving at constant speed. The shaft i8 may be driven from shaft i5, and for this purpose may, for instance, be coupled with shaft is or may form an extension thereof. Shaft 13 carries two cam discs 5! and 58. Each of these cam discs is equipped with cam flanks 57a or 55a which are spaced from each other on the periphery of each cam in accordance with the period of the pulses. ihe cam discs are further provided with cam portions E'ib and 55?), respectively, which have a constant radius relative to the axis of revolution. The cam flanks. iila or 58a are located immediately behind the constant-radius cam portions 5??) or 58?) in the running direction of the cam disc (indicated by arrows). The cam flanks 57a and 53a have a steeply declining radius.

Two movable switching levers and ii are pivoted by respective pivot pins 55 and it. Each lever is biased by springs, such as the spring assembly shown at 53 and 5 so as to be urged from opposite sides against the respective cam discs 58 and 57. The switching levers have a feeler nose 45b or ilb engaging the pertaining cam discs 58 or 5'1. Each lever is further equipped with a tappet portion 45a or 47a. During revolution of the cam discs 5'1, 58, the levers oscillate about their respective pivots, and the tappets 46a and 47a actuate a movable part 48 of a pulse switch in mutually opposing directions, the actuation being effected each time one of the levers 46 and 4'! drops along one of the cam flanks to its active position.

The movable part d8 of the pulse switch is pivoted on a pivot pin ll and carries a contact control piece as of insulating material. In one position of the movable switch part, the insulating piece 45 separates two stationarily mounted con tact springs as with a contact 52. Mounted on the peripheral end of the movable part 38 is a detent sea which coacts with a roller 5i movably journalled on a leaf spring 52, thus providing a snap action. The pulse contact device, therefore, operates as a snap-action switch. The stationary contact springs 55 are mounted on one leg of a U-shaped stationary holder 56 so that the position of springs 55 relative to the movable switch part is may be adjusted by means of a set screw 59 screwed through the other leg of holder 56.

The above-mentioned locking means for alternately locking one of the two switching levers =35,

*4! while simultaneously releasing the ether lever under control by the pulse-wise reciprocating switching member #33, comprise a teeter revolvable about a pivot pin 55. The two arms 45a and 45b of the teeter are linked to respective locking rods and (ii guided for longitudinal shifting motion. A third arm 450 of the teeter is straddled by a fork dd mounted on the mechanical switching member 43. During reciprocating movements of the member 43, the locking rods 66, Bl are alternately shifted in their axial directions so that in each of the two end positions of member 48 one of the respective rods is placed in front of the pertaining switching lever 45 or t? thus locking the lever while at the same time the other rod is withdrawn from the pertaining lever thus releasing that lever.

The cam discs 5? and 58 are so positioned relative to the cycle of movement of the control elements (pulse control disc it) that the alternate release of the switching levers 56 and :1 occurs in an interval of time in which the feeler nose of the one switching lever being released at a time comes into the range of the constant-radius cam portion 5??) or 581) preceding the cam flanks.

It will be understood that the keys iii and the above-described elements 4!, 43, 45, as, ii, 48 are all movably mounted on a common stationary and rigid frame structure (not shown) on which the shafts i3, it are revolvable and the locking rods 55, ii are slidable, and which also carries the spring means 53, 5d, the holder and the contact springs 55.

The operation of the apparatus is as follows. When key iii is being depressed, feeler pin 42 of feeler member s! is moved into the cam groove 27, and the same key operation causes the pulse control cam Hi to turn one revolution at constant speed, whereafter the feeler pin 42 is released to return into its original position. During the revolving period of pulse control cam i l, the feeler member ii, tracing with its pin 32 the groove contour, moves back and forth and imparts its oscillations through arm aid to the switching member .3 common to all pulse control discs. Assume that member i3 just starts moving from its illustrated position in the clockwise direction and that this is to commence the issuance of an individual current pulse. The clockwise movement of member 53 is imparted through fork M and arm 450 to teeter Hence teeter E5 oscillates accordingly. It withdraws the locking rod 55 from switching lever 5 thus releasing this. lever. At the same time the teeter 45 advances the locking rod 5% thereby locking the switching lever ll. The released switching lever 55, under its spring bias, has its feeler nose 55b pressed against cam disc 5? at a point within the range of one of the cam portions 571). As soon as the feeler nose 45?) reaches the range of the next following cam flank 55a, this being the case when the cam disc 5? has turned a corresponding amount in'the clockwise direction, the switching lever is reaches its active condition relative to the pulse contact device. That is, the switching lever 65, when dropping with its nose 3512 along the cam flank, continues moving under its spring pressure so that tappet 460. tips the snap-action switch part %3 thus opening the contact 52 and establishing the no current condition. The switch part 48 is held in this switching condition by the resiliently mounted roller 5i, while the switching lever diiduring the further revolutionofcam disc 57, is returned to its original position.

In an analogous manner, the switching lever 41 is effective to actuate the movable switch part 43 in the opposite direction, again under control by feeler member 4| and pulse-control disc M. The ieeler nose 41b of lever 4! slides on a constant-radius portion 58b of cam disc 58 until the next-following cam flank 58a is reached. At this moment, the tappet 41a of switching lever 47 tips the switching element 48 to the other position thus establishing the current condition. Cam 5?, therefore, always controls the start of a current pulse, and cam 58 always the end of the pulse.

The cam discs 51 and 58 are arranged on shaft IS with such a mutual angular displacement that the two cam flanks successively scanned first on one and thereafter on the other cam during each full reciprocation of switching member 43, are spaced apart a distance corresponding to the length of the individual pulse. The cam discs 51 and 58, preferably, are angularly adjustable relative to each other on shaft I8 so that the moment when the switching levers reach the active condition may be adjusted relative to the cycle of movement of switching member 43. This permits advancing or retarding the operation of the pulse contact device so that the pulse duration may be adjusted within given limits. If the cam discs 51, 58 are arranged on the shaft 83 common to the pulse control disc I4, i. e. if shafts l8 and I3 are integral or interconnected, the cam discs 51, 58 are preferably also adjustable angularly with respect to the pulse control cams. The angular setting of the discs can then readily be calibrated so that each switching lever when released always drops first upon one of the cam portions 511) or 58b of constant radius.

It is apparent that, with a constant revolving speed of the cam discs 51 and 58, the current pulses being issued by the contact device have a constant pulse duration and constant pulse periods regardless of any inaccuracies with which the pulse control discs may be affected within certain limits. These limits are determined by the length of the constant-radius portions 5'") and 58b of cam discs 51 and 58. No matter how large any time error in the stroke imparted to the switching member 43 may be, the desired pulse correction is always obtained, provided the feeler nose of the switching lever then being released will drop into the range of one of the constant-radius cam portions 51b or 58b. This condition, however, can be met without much efiort.

In conjunction with the improvement in pulse transmission, it is significant that the number of the corrective cam discs need not, like that of the pulse control disc, correspond to the total number of code combinations, but that only two cam discs 51, 58 of high accuracy are needed for any number of pulse control discs [4 of lesser accuracy requirements. Besides, the exteriorly cammed discs can be more easily manufactured than the pulse discs with lateral grooves.

The pulse contact device, of course, may also be designed as a reversing switch to make the teletypewriter applicable for double-current (plus-minus) operation.

I claim:

1. Apparatus for transmitting current-pulse combinations, particularly in teletypewriters, comprising selectively operable control means, a mechanical switching member reciprocable between two positions under control by said control means in accordance with the pulse combination having cam flanks mutually spaced on the disc periphery in accordance with the pulse cycle periods, two movable switching levers engageable with the cam periphery of said responsive discs, said contact device having a movable switch part, and said levers having respective means engageable with said part for controlling said part in mutually opposing directions when the respective switching levers are controlled by said respective discs to move to an active position, and locking means having an element in engagement with said switching member and being selectively engageable with one of said respective levers for alternately locking one of said respective levers and releasing the other lever in accordance with the reciprocation of said switching member, each of said levers when released by said locking means being in said active position when entering into the range of one of said cam flanks.

2. In pulse-combination transmitting apparatus according to claim 1, each of said cam discs having cam portions of a constant radius relative to the axis of cam revolution, and said flanks being located directly behind said respective cam portions in the direction of cam revolution and having a steeply diminishing radius.

3. In a pulse-combination apparatus according to claim 2, said two cam discs having, relative to the cycle of movement of said control means, a phase adjustment wherein each of said switching levers at the release moment engages the starting point of one of said constant-radius cam portions ahead of one of said flanks.

4. In a pulse-combination apparatus according to claim 3, said control means comprising pulsecontrol discs having a common shaft on which said pulse-control discs are firmly mounted, said cam discs being also mounted on said shaft and being angularly displaceable relative to each other and relative to said pulse-control discs, whereby the moment when said levers reach said active position may be displaced relative to the reciprocating period of said switching member in order to adjust the pulse duration.

5. Pulse-combination apparatus according to claim 1, comprising spring means engaging said respective switching levers and having on said levers a force directed toward said respective cam discs so as to act through said levers upon said movable contact piece when said levers pass over one of said cam flanks.

6. Pulse-combination apparatus according to claim 1, comprising spring means urging said levers toward said respective cam discs, said locking means having a teeter coupled with said switching member to rock when said switching member is reciprocating, two axially displaceable locking rods linked to opposite sides of said teeter and alternately positioned on the cam-disc side of said respective switching levers for locking said levers.

7. In a pulse-combination apparatus according to claim 1, said contact device having snap-action means joined with said contact piece.

OTTO MOSER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,394,765 Hagelin Feb. 12, 1946 2,522,461 Potts Sept. 12, 1950

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