US2472733A - Key operated transmitter - Google Patents

Description

June 7, 1949.' I c. w. SWAN 2,472,733

KEY OPERATED TRANSMITTER Filed Aug. 6, 1943 3 Sheets-Sheet 1 INVENTOR CA RL W. SWAN ATT RNEY June 7,1949. w. SWAN I 2,472,733

KEY OPERATED TRANSMITTER FiledAug. e, 1943 s Sheets-Sheet 2 VIE INVENTOR CARL .W. SWAN nee.-

AT RNEY Jung 7, 1949.

Filed Aug.

FIG. 7

C. W'. SWAN KEY OPERATED TRANSMITTER :s $heets$heet a Patented June 7, 1949 KEY OPERATED TRANSMITTER Carl w. Swan, Skokie, 111., assignor to Telety e Corporation, Chicago, 111., a corporation of Delaware Application August 6, 1943, Serial No. 497,591 2 Claims. (01. m ss) This invention relates to apparatus for the transmission of permutation code signals and more particularly to transmission apparatus in which predetermined permutation code signals only are transmitted.

Certain signals of a permutation system are sometimes assigned to special supervisory control purposes. Under such circumstances a special limited keyboard becomes convenient which accommodates these code signals only, but as the particular code combination may vary according to custom or necessity it is desirable that the limited number of keys may be altered through the entire range of the permutation code.

The object of the present invention is to provide apparatus for the transmission of certain code signals only wherein such signals are optionally predetermined according to permutation.

A further object of the invention is to provide means whereby an operator of the apparatus may, by a visible indication, be notified of the transmitted code signal.

The apparatus, in general, consists of a set of keys, each one upon being depressed, operates a bail to permutably actuate code bars. An extension on each bail establishes two electrical circuits, one of which lights a signal lamp to indicate the key that has been depressed. The second circuit energizes an electromagnet which through an armature releases a cam distributor for a cycle of operation, whereby the predetermined code signal is transmitted over an associated signaling channel.

A more detailed understanding of the invention may be had from the following description with reference to the accompanying drawings in which:

Fig. 1 is a front elevational view of transmitting apparatus embodying the present invention;

2 is a side elevational view of the apparatus shown in Fig. 1;

Fig. 3 is a side sectional view, partly broken away, taken approximately on line 33 of Fig. 1;

4 is a side sectional view, taken approximately on line 3-4! of Fig. 1, showing in detail a timing device utilized in the present invention;

Fig. 5 is a plan sectional view taken approximately on the line 5-5 of Fig. 1;

Fig. 6 is a detail sectional view taken approximately on the line 66 of Fig. 5; and

Fig. '7 is a schematic wiring diagram showin the electrical circuit of the apparatus.

The apparatus is mounted on a vertical base II which, in turn, can be mounted securely by any suitable means (not shown) in its desired operating position. A bracket i2 is mounted securely to the base .I l, on the left side, by means of screws l3. Mounted securely to the bracket I 2, in a vertical position, is a rod l4 which is held in place thereon by means of screws IE. Mounted pivotally upon the rod I4 are three key levers [1, I8, and I9, upon which are secured key tops A, B, and C, respectively. The key levers I1, I 8, and I9 extend toward the right and terminate in ends 2|, 22, and 23, respectively. These levers extend through an opening in a bracket 24 which iss-ecured to and at right angles to the base I I.

Adjacent the lever ends 2|, 22, and 23, are three vertically positioned levers 26, 27, and 28, which are so placed as to be engaged by the lever ends 2 I, 22 and 23 upon the depression of any of the key tops A, B, or C. The levers 2E, 21, and 28 are integral parts of code bails 29, 3|, and 32, respectively, which are pivoted in a block 33 which is fastened securely perpendicularly to the bracket 24. The code bails 29, 3!, and each have a series of fivecode lugs 34 thereon, each lug corresponding to an impulse of a five-unit permutation code signal. The code lugs 34 are reversible and may be positioned with their projection portions either above or below the code bails. Thecode bails 29, 3|, and 32 each have an arm 36, 3'! and 38, respectively, as shown in Figs. 2, 3, and 4.

Pivoted within slots in the block 33 are five code levers 39, which are held normally in an outward position by means of individual springs M which are connected to a rearwardly extending lug at the bottom of each of the code levers. The code levers 39 are held in their correct lateral position by means of guide plates 42 (Figs. 2 and 3) pairs of which are positioned one on each side of the code levers. The front edge of the code levers are formed with lugs and slots. A code lug 34 may engage the lugs, or enter into the slots, upon the forward movement of a code bail, depending on the position of the projection portions of the lug with respect to the bail.

The top edge of the code levers are formed with an upwardly-extending arm at its end, as designated by the numeral 43. The rearward portion of the topvedge of the code levers is formed with two lugs having a slot separating them. This is so designed that a locking bar 44 may enter within the slot between the two lugs or may be positioned in front of the forward lug, and which acts to lock the code levers either in their normal position or in an inward position, depending on the signal which is to be transmitted.

Referring now to Fig. 5, a shaft 46 is journalled within bearing brackets I2 and A! which are secured to the base The shaft 46 is composed of two cam assemblies, one each toward its right and left ends, and which are separated by a section of integral shafting. Surrounding the middle section of the shaft 46 is a hollow sleeve which is free to rotate independently of any movement of the shaft. Positioned securely at one end of the sleeve 5| is a gear 52 which engages a pinion 53 (Fig. 4) fast to a shaft of a motor 54. The sleeve 5| is continuously rotated through the engagement of its gear 52 with the pinion 53 of the motor 54. The shaft 46, however, does not rotate continuously.

A cam assembly which has been designated generally by the numeral 48 has five cams 56 to 60 inclusive and a disk 6|, thereon. Five cam followers 64 to 68, inclusive, are pivotally mounted in slots in a block 63 which is secured to the base H, and are normally held in a position against the cams '56 to 66, by means of springs I0, one individual to "each cam follower.

The cam follower 64 is in engagement with the 'cam56, Fig. 2, and its forward end is connected to 'thelocking bar 44, previously mentioned. As the locking bar 44 'is made of sufiicient width to engage all five of the code levers 39, it is necessar'y'to have an actuating member at each of its ends. Therefdre, the end opposite from that formed by the cam follower 64 is formed by the ca'm'follower 68, which is en a ed by the cam 68. Thus, upon rotation of the shaft 46 the cam followers 6'4 and 68 will be rocked counterclockwise, Fig-2, due to'the contour of the cams 56 and 6f],

during a predetermined portion of the cycle of operation of the shaft 46. This. in turn, will cause the'locking bar 44 to move into the notch or in front of the lug on the code levers 39, thus lockingthe code levers in-either their forward or rearward positions.

Another cam follower 65 is positioned so as to be-engaged by a cam 51 and is formed with a member" extend ng upwardly and to the rear of the cam'and thecam shaft, and a forwardly extending'member 12 in front of the cam. and the camshaft. The member 1! serves to engage and release-a clutch element, the operation of which will-be hereinafter explained. The member '!2 acts to lock an armature 13, the operation of which will also be thoroughly explained later.

The-cam followers 66 and 6? are each formed with=a forwardly-extending arm, in the sha e of a'hook, which is used to lock the bail and the I bail'3l, respectively, in its forward position. This locking operation extends through a portion of thecycle of operation of the shaft 46, depending o'nthe contour of the associated cams 5S and 59. The disk 6| has a notch in its peri hery which is engaged'b'y a roller 14 (Fig. 3) at the end of the cycle of 'operation' of'th'e shaft 56. and'which issecure'd at'the end of a pivoted rod 16, and norln'allyheld against'the surface of the disk by means of'a spring Tl. Upon the rotation of th'e' sh'aft 46 to a position whereat the roller 14 canengage the notch in the disk 6 I. which it will be forcedto do by the action of the spring 1'! pivoting the rod 'l fitoward the disk,'the clutching mechanism will'be completely released, as explain'ed later, to serve as an anti-singing device. Thusfthe roller 14 detents the disk 6| and its connected clutching mechanism, with respect to the member 1|, so as to positively disengage the clutch te'thand prevent any rasping due to inthe follower 6 5.

energization of the magnet 19 the armature 73 will be drawn toward the magnet, its lower end being moved free from the upturned end 72 of When this occurs the corres'ponding spring 10 pivotes the cam follower 65 in a clockwise direction as viewed in Fig. 3, which results in the member H likewise moving in a clockwise direction and releasing the clutch mechanism, thus allowing the shaft 46 to be engaged for rotation.

The locking bar 44 is formed with a pivoted downwardly-extending lever 82 having a hook at its end (Fig. 2), which, under certain conditions, engages an associated hook which. is formed on an upwardly-extending lever 83 which is pivotally mounted in a slot in the block 33. When the hooks engage each other a non-repeat condition exists in the transmitting apparatus, as will be explained fully in conjunction with the ope ation of the apparatus.

Positioned adjacent the block 33 and below the levers 36, 31, and 38 (of the code bails 29, 3|, 32, respectively), are three double contact electrical switches 84, 86, and 81 (Figs. 2, 3, and 4). These switches are normally open, no electrical circuit being established as a result. The levers 36, 37, and 38'are positioned immediately above the electrical switches so that if one of the three bails is pivotedin a clockwise direction (Figs. 2, 3, and 4) the lever will be forced downwardly to engage the top insulated portion of the electrical switch and cause it to move downwardly, thus closing the two contacts and establishing two electrical circuits. The closing of one of the contacts establishes a circuit which energizes the magnet 19, which, in turn, causes the armature 13 to be drawn "toward'the magnet thus allowing the cam follower 65 to pivot in a clockwise direction, as viewedin Fig. 3, and also allows the member (I to move in a clockwise direction, thus releasing the shaft 46 to rotation by the engagement of the clutching "mechanism with the sleeve 5|. The closing of the second electrical contact in the switch establishes a circuit in which is connected an electric light corresponding to the bail which has-been moved in the clockwise direction. The establishment of this circuit causes one of three electric lights 88, 89, or to be illuminated, indicating to the operator which of the three key tops A, B, or C has been depressed.

Positioned just behind the upwardly-extending arm 43 of the code levers 39 are six electrical switches 92 to 91, inclusive. The electrical switch 92 is; normally in a closed position, whereas the electrical switches 93 to 97, inclusive, are normally open. The latter switches 93 to 9?, inclusive, are aligned with the upwardly-extending arms 430i the code levers 39, one electrical switch being behind each of the five code levers. Upon a clockwise movement (Fig. 2) of any of the code levers, by engagement with the corresponding code'lugs on the code bail, the upwardly-extending arm 43 will be moved inwardly, thus engaging its associated electrical switch and closing it. These switches, in turn, correspond to the five impulses in a code signal, such as the Baudot five-unit code. The switch 92, which is normally closed, is opened during a certain part of the cycle of operation of shaft 46, by means of a lug 98 (Fig. 2) which forms an end of the locking bar 44. At the same time that the looking bar l moves downward to lock the code levers 39 in their forward or rearward positions the lu 98 thereon will cause the electrical switch 92 to be opened, thus breaking a previously-established circuit. Such a circuit interruption is necessary in order to deenergize the magnet E9 which has previously been energized by the closing of one of the electrical switches 84, 86, or 8'! upon the depression of its corresponding key top. This conditions the magnet it so that it will be in readiness to reinitiate a cycle of operation of the shaft 46 when one of the key tops A, B, or C is again depressed, providing that the switch 92 has i been opened, thus allowing the armature to have returned to its normal position.

Fastened securely to the sleeve 5| so as to rotate therewith is a ratchet wheel I M (Fig. 5) which is located at the opposite end of the sleeve from the previously mentioned gear 52. Connected to the disk BI, by means of a post I92 (Fig. 6) are three pawls 103. Each of these pawls has a tooth HM thereon, which are in staggered relation to each other. These teeth are positioned in such a manner so that upon engagement of the clutching mechanism, later to be explained, one of the three teeth will immediately engage the teeth on the ratchet wheel MI, as the teeth are together staggered a distance equal to the distance between adjacent teeth on the ratchet wheel. The pawls It? each have individual springs H35 urging them in a, counterclockwise direction, as viewed in Fig. 6. When a tooth on one of the pawls engages the ratchet wheel power from the ratchet wheel and disconnecting the drive to the shaft 36. A post we, secured to the disk ti, limits the clockwise movement of the pawls I93. Upon the armature 13 being moved, due to the energization of the magnet l9, the cam follower 65 moves upward, as already explained, with the result that the member 'iI likewise moves upward and releases the ends of the pawls M3. The springs I85 cause the pawls to be urged toward the ratchet wheel, the tooth of one of the pawls engaging therewith, and thus again causing the shaft 4% to rotate through a cycle of operation.

A timing device is disclosed in Fig. 4 which permits the visible signal, which is given when any one of the three key tops has been depressed, to remain operative for a predetermined length of time. This timing device is associated with one key only, key top A being designated as the associated key in the present disclosure. Surrounding a narrow section of the sleeve 55, on an inner surface, is an eccentric let about which is positioned a pawl lill. The pawl ltl, which is free to rotate in an eccentric manner with respect to the constantly rotating sleeve 5|, is positioned by means of a spring I08 so as to be in to tilt, inclusive.

engagement with a ratchet wheel I09 which is secured to the bracket 24 (Fig. 1). A second pawl III is pivotally secured by means of a, rod II2 which extends from the lower portion of the code bail 29 in such a manner that the spring I08 holds it also in engagement with the ratchet wheel I09. The ratchet wheel I09 has two posts II3 thereon, placed toward the outer periphery of the ratchet. In two places teeth are omitted from the periphery of the ratchet I09, as illustrated at I I4.

A bell crank lever i it is mounted pivotally upon the bracket 24 in such a position that one arm 5 it may be engaged by the posts 1 It on the ratchet wheel We to pivot the bell crank H6. An opposite arm I it? of the bell crank H6 passes through opening in a plate H9 which is mounted directly over the electrical switch 8A, with a free end of the plate in contact with the electrical insulation at the top of the switch. The bell crank lever I i3 is urged toward the posts M3 by means of a spring IZI and attempts to urge the arm II8 out of the openin in the plate MB. This is possible only when the lever 36 of the code bail 29 is moved downwardly due to the inward movement of the code bail, and exerts pressure on the top of the plate lie, moving it downwardly, and thus freeing the arm i it from the opening in the plate H9.

The cam assembly as is formed of six cams I23 Acting as cam followers for the cams H23 to I28 are six electrical switches I3I to I38. inclusive. Each of the electrical switches l-Fii to Hit is directly connected with an individual electrical switch til to ill, previously mentioned. Five of switches correspond to the five impul es in the standard Baudot code, the sixth switch corresponding to a stas-stop impulse,

h is usually associated with such code transon. At certain intervals in the cycle of operaticn of the shaft ie the switches are successively closed, which acts as distributor for the code impulses which are being sent out over an outgoing line 538. In the event that a switch 92 to ill not been closed, there will be no impulse at the corresponding electrical switch I3! to I36. This results in a no--current condition on the transmitting line, when the appropriate cam cl see that switch. which results in. a spacing impulse being transmitted.

In describing the operation of the apparatus the description. will proceed on the basis that the A key top has been depressed, as the operation of the device is very similar upon the depression of the B or C key tops. The major difference is that there is no timing device afliliated with these latter key tops actin to hold an electrical switch closed for predetermined time interval to allow the visible to indicate to the operator of the transmitting apparatus that a certain key top been depressed. However, certain locking levers have been provided in its place to insure the signal during a complete cycle of operation of the shaft 46.

The operation of the device is as follows:

Upon depression of the A key top, key lever I1 is pivoted inwardly on rod it, its end 2I engaging the upper end of the lever The lever 26 is thus pivoted about its base, where it is secured in block causing it to move inwardly and also imparting a corresponding movement to the code bail 29, which is an integral part of the lever. The code lugs St on the code ball 29 have been prenositioned with the body projection of the first two lugs on the left-hand side of the bail (see Fig.

1) above the code bail whereas the remaining three lugs are positioned with their body projectlons below the code bail. The two lugs positioned with their body projections above the code bail 29 will engage the lugs on the front edge of the code levers 39, whereas the lugs positioned with their body projections below the bail will enter a slot formed in the front edge of the code levers. The two code levers 39 engaged. by the code lugs will be forced inwardly against the tension of their springs 4|, pivoting about their point of connection in the block 33. The lever 36, of the code bail 29, will exert pressure upon the plate H 9, causing the electrical switch 84 to be closed. Upon the closing of the switch 84, an electrical circuit will be established which will energize the magnet 79, and will also establish a circuit to cause the electric light 89 to be illuminated, thus acting as a signal that key top A has been depressed. The energization of the magnet I9 causes the armature I3 to move to the right, as viewed in Fig. 3, thereby releasing the upturned end I2 of the cam follower 65 and allowing the cam follower to move under the tension of its associated spring iii. The cam follower 55 will pivot in a clockwise direction, as viewed in Fig. 3, thereby removing the member '5! from its blocking position with respect to the three pawls I03 of the clutching mechanism. The three pawls will move in a counterclockwise direction (Fig. 6) under the force of their individual springs I85 and cause a tooth on one of the pawls to engage the teeth in the ratchet wheel ItlI. This, in turn, causes rotation of the shaft 49 through engagement with the constantly-rotating sleeve The contour of the cam 5?, which is associated with the cam follower 55 is of such a shape that the cam follower will be depressed immediately after the latter operation described has occurred, and held in a downward position against the tension of the spring I9, so that the armature 13 may again resume a blockin position upon the upturned end I2 of the cam follower 55 when the magnet becomes deenergized and the spring 8I moves the armature :3 to its normal position. The

downward movement of the cam follower 55 causes the member II to be moved downward also, which positions it to engage the three pawls I93 upon the completion of a cycle of operation of the shaft 46, causing the pawls to be moved outwardly against the influence of their corresponding springs IE5 and thus disengage the engagin tooth from the ratchet wheel I OI, the shaft 46 no longer being rotated. The roller I4,

at the lower end of the bell crank lever I6, will I enter the notch in the disk ti under pressure of its associated spring I! and thereby positively disengage the tooth of the pawl from the ratchet wheel I9I. This, as previously explained, serves as an anti-singing device.

The two selector levers 39, corresponding to the code lugs 34 whose body projections were positioned above the code bail 29, have been forced inwardly, as previously mentioned. Their upturned arm 43 moves inwardly and closes the two corresponding electrical switches 96 and 91. Immediately thereafter the cams 55 and 60 cause the cam followers 64 and 68 to move downwardly, against the tension of their corresponding springs I0, causing the locking bar 44 to move downwardly also and position itself against the rear top edge of the code levers 39, thus holding the code levers in that position. The other three code levers are locked in their normal, outward position. The Operator can now release the A key top, but

the code levers will be held in their respective positions until a cycle of operation of the shaft 46 has been completed. At the appropriate position of the shaft 46 the cam followers 64 and 68 will be moved downwardly, by means of their springs I9, resulting in the locking bar 44 moving upwardly out of locking engagement with the rear top edge of the code levers, thus allowing the code levers to move to their normal, outward positions if not already there.

Upon the downward movement of the locking bar 44 its lug 98 will come in contact with the insulator on the electrical switch 92 and force it, outwardly, thereby breaking the circuit in which the switch 92 is connected. The opening of the switch 92 causes the circuit in which the magnet I9 is connected to be likewise opened and thus breaks any current to the magnet, causing it to stay deenergized. Thus, the magnet I9 will not be energized to cause a second cycle of operation of the shaft 45 until the switch 92 has been restored to its normal closed position.

Upon depression of key top A and the inward movement of its corresponding code bail 29, the lever 83 was also caused to pivot inwardly, positioning its hook to be engaged by the hook on the lever 82 in the event that the lever 82 were moved downwardly. The downward movement of locking bar 44 causes the lever 82, connected thereto, to likewise move downwardly. In the event that the lever 83 is still in its inward position, due to the A key still being held in a depressed position, the hooks on the levers 82 and 83 will engage each other, which will prevent the lever 92 from moving upwardly upon the subsequent upward movement of the locking bar 44 by its associated cam followers 64 and 58. As long as the locking bar 44 is held in its downward position, its lug 98 will hold the electrical switch 92 in its open position, thus breaking the electrical circuit of which it is a member. Therefore, the magnet "I9 will not be energized and so no further signals can be transmitted. This feature acts as a non-repeat device so that no matter how long the operator depresses the selected key top only a single signal will be transmitted over the line.

As previously mentioned, the electrical switches 95 and 91 were closed. These, in turn, are directly connected to the electrical switches I35 and I36. Upon the rotation of shaft it and of the cam assembly 69, the cam I29 will close its associated switch I 3I to act as a start signal, for the code signal to be transmitted over the line conductor I38. The cams I23 and I24 will then, in succession, close their corresponding electrical switches I 36 and I35, which results in marking impulses being sent over the line conductor I38. As the electrical switches 96 and 9? were the only ones which were closed by the code levers 39, the remaining three electrical switches, namely, 93, 94, and 95, will not establish any electrical circuit with the electrical switches I32, I33, and I34. Thus, as the cams I25, I26, and 12? close these switches in succession, no marking impulses will be transmitted, but spacing impulses instead. Therefore, as the first two code units were the only ones during which marking impulses were transmitted, the letter A will be transmitted over the outgoing line conductor 38. As the cam assembly 49 is a part of the shaft 49, it will stop its rotation when the cycle of operation of the shaft 46 has been completed, as previously described. The B or C signals are achieved in the same manner by a similar operation to the one just described. Any predetermined code signals can be sent out by merely changing the body projections of the code lugs 34 with respect to the code bails 23, 3i, and 3.2. Upon the depression of the A key top the code ball 29 is moved inwardly, and accordingly its lever 36 is moved downwardly, exerting pressure on the plate H9 to close the electrical switch 84. Upon the downward movement of the plate H9 the end I I8 of the bell crank lever H is freed from the plate I I9 and the bell crank lever is pivoted in a clockwise direction, as viewed in Fig. 4, by means of its spring Hi. The bell crank lever H6 will remain in this position until one of the two posts H3, secured to the ratchet wheel I09, engages its upper hooked end H7 and causes the bell crank lever to be pivoted against its spring IZI in such a manner that its lower end I IE will once again be positioned in the opening in the plate H9, allowing the plate H9 to rise, due to its resilience, and thus open the electrical switch 84. As long as the bell crank lever is positioned to hold the switch 84 in its closed position, the corresponding electric light 88 will be illuminated, designating that key top A had previously been depressed. Movement is imparted to the ratchet wheel I09 by means of the two pawls I97 and I I I. The pawl I01 is mounted eccentrically upon the sleeve 5|, and rotates continuously therewith. Rotation of the eccentrically mounted pawl I01 causes the ratchet wheel I09 to be advanced stepby-step through engagement with the teeth on its periphery. The second pawl III is mounted on the rod H2, which extends from its position of securement on the lower end of the code ball 29. Any depression of the A key top, which causes the code bail 29 to be moved inwardly, will cause the pawl III to be moved upwardly, which through its engagement with the teeth on the periphery of the ratchet wheel I09 causes a single step to be imparted to the ratchet. This is necessary because of the two spaces I it on the periphery of the ratchet I09 where teeth are omitted, so made that there will be a pause immediately after the posts H3 have pivoted the bell crank lever H6. The spaces I I4, where teeth have been omitted, are so positioned in respect to the posts H3 that the pawl I07 will not reach this portion of the ratchet wheel I09 during the time that the signal is being sent out and the electrical switch 84 is closed. The spring I08 is positioned as to positively insure that the pawls 101 and I II will be in engagement with the teeth on the ratchet wheel I09.

The operation of the apparatus, upon the depression of the B and C key tops as previously mentioned, is very similar to the above described operation with the exceptions that there are no timing devices connected for operation with these keys.

A second distinction between the operation of the transmitting apparatus upon depression of the B and C key tops and the depression of the A key top resides in a special locking mechanism which holds the bail, once moved inwardly, in this position until the cycle of operation of the shaft 46 has been completed. The cam followers '66 and 61, which are under the control of the cams 58 and 59, have a hooked forwardly extending portion which is associated with the bails 3| and 32. After either the bail corresponding to the B or C key tops has been moved inwardly, and the shaft 46 has started into rotation, the cams 58 and 59 will cause the cam followers 66 and 61 to move downwardly, which results in th hook at the front end of the cam follower hooking over the bail and securing it, thus preventing it from returning it to its outward position in the event that the operator were to immediately release the selected key. Such a locking device has been found necessary as there is no timing device associated with the B and C keys and it is used to insure that the code bails 3I and 32 will remain in their inward position for a certain length of time so that their levers 31 and 38 may be in contact with the electrical switch 86 or 31 for a sufficient period of time for a signal to be given, by means of the lamp bulbs 89 and 90.

Although a specific embodiment of the invention has been shown and described, it will be understood that this is but illustrative and that various modifications may be made therein without departing from the scope and spirit of this invention.

What is claimed is:

1. In a signal transmitter, a plurality of keys, a bail under the control of each of said keys, a plurality of selector levers permutably controlled by said balls in accordance with predetermined signals, a blocking bar to hold said selector levers in their permuted positions, a bail lock forming a portion of said blocking bar, electrical contact means operated by said selector levers, a distributor for controlling the transmission of said predetermined signals in accordance with said electrical contact means, means responsive to the operation of any one of said balls for releasing said distributor for a cycle of operation, and means under the control of said blocking bar operating after said distributor has been released to disable said distributor releasing means until after said selected ball has been released by said ball lock.

2, In a signal transmitter, a plurality of keys, selector means permutably controlled by said keys in accordance with predetermined signals, electrical contact means operated by said selector means, a distributor for controlling the transmission of said predetermined signals in accordance with said electrical contact means, means for releasing said distributor for a cycle of operation upon the selection of one of said keys, and means operating after said distributor has been released for a cycle of operation to prevent said distributor releasing means from operating to release said distributor for another cycle of operation until after said selected key has been released and said distributor has completed its cycle of operation.

CARL W. SWAN.

REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,073,130 Havland Sept. 16, 1913 1,197,273 Ehrhardt Sept. 5, 1916 1,454,990 Wilcke May 15, 1923 1,823,319 Dickinson Sept. 15, 1931 1,864,074 Krum June 21, 1932 1,873,729 Wheelock Aug. 23, 1932 2,182,355 Rusted et a1. Dec. 5, 1939 2,183,022 Krum et al Dec. 12, 1939 2,238,363 Hadley Apr. 15, 1941 2,258,266 Sengebusch Oct. 7, 1941 2,267,936 Marrison Dec. 30, 1941 2,347,108 Hubbard Apr. 13, 1944

Images