US3427411A

US3427411A - Apparatus for driving rotary electric switches

Info

Publication number: US3427411A
Application number: US564219A
Authority: US
Inventors: Georges Janoska
Original assignee: RESPONSABILITE Ltd SOC LAMY D
Current assignee: A RESPONSABILITE LTD SOC LAMY D'ETUDES ET DE RECHERCHES SOLER SOC; RESPONSABILITE Ltd SOC LAMY D
Priority date: 1965-07-12
Filing date: 1966-07-11
Publication date: 1969-02-11
Anticipated expiration: 1986-02-11
Also published as: GB1148445A; DE1563721A1; NL6609648A; BE683920A; SE301834B; CH470748A; AT258401B

Description

Feb. 11, 1969 G. JANOSKA 3,

APPARATUS FOR DRIVING ROTARY ELECTRIC SWITCHES Filed July 11, 1966 Sheet of 5 Feb. 11, 1969 Filed July 11, 1966 G. JANOSKA 3,427,411

APPARATUS FOR DRIVING ROTARY ELECTRIC SWITCHES Sheet 2 ofs ouiaulzuuunzzo, o o

IL 509 a.

I I I I I I I I 51II I I I I I I I I I I I/ I I I I I I I I I I II 5m b if Feb. 11, 1969 a. JANOSKA 3,427,411

APPARATUS FOR DRIVING ROTARY ELECTRIC SWITCHES Filed July 11, 1966 Sheet 5 or 5 Y m-1M..-

Feb. 11, 1969 I a. JANOSKA 3,427,411

APPARATUS FOR DRIVING ROTARY ELECTRIC SWITCHES I Filed July 11, less Sheet 4 or 5 G- JANOSKA Feb. 11, 1969 I APPARATUS FOR DRIVING ROTARY ELECTRIC SWITCHES Filed July 11, 1966 Sheet United States Patent 3,427,411 APPARATUS FOR DRIVING ROTARY ELECTRIC SWITCHES Georges Janoska, Courbevoie, France, assignor to Societe a Responsabilite Limitee: Societe Lamy dEtudes et de Recherches Soler, Courbevoie, Hauts-de-Seine, France, a corporation of France Filed July 11, 1966, Ser. No. 564,219 'Claims priority, application Switzerland, July 12, 1965,

9,723/ 65 US. Cl. 20038 6 Claims Int. Cl. H01h 3/32 ABSTRACT OF THE DISCLOSURE The invention relates to a programmed sequential switching device.

It refers more particularly to a sequential switching device comprising a plurality of rotary switches, wherein the successive switching states are determined by a programme established on the basis of scanning and timing parameters.

In know device the scanning parameters of the switching programme represent the selection of the address or destination corresponding to each input and/or output pole, which forms the stored space division switching programme. The time division switching programme is the rhythm at which are driven the said switches scanning the input and/ or the output poles.

In these known devices, one of the switches, being at a given moment in a position n, will next occupy either the position n+1 or the position n- 1, so that these devices are incapable of effecting varied programmes comprising a large number of switching states or comprising a variable succession.

The present invention seeks to make it possible to programme, in any succession, the sequence of states of a switching device.

Another object of the invention is to make the timing parameters and the scanning parameters of the switching devices independent of each other and therefore separately programmable.

A further object of the invention is to provide means for introducing and storing the timing and scanning parameters in the switching device.

The invention has the further aim of permitting the construction of switching devices capable of being driven mechanically, with high positional accuracy, in accordance with programmes comprising stopping and driving phases whose magnitude and duration may be varied.

This invention provides a sequential switching device capable of memorising and operating according to a programme, the device comprising a plurality of rotary switches connected to a common motive power input by kinematic chains comprising uniform motion drive means and intermittent drive means at least one of the switches having contacts for electrical connection to corresponding external signal sources and being capable according to the said programme of alternately moving to act as a Patented Feb. 11, 1969 scanning switch for scanning the signals from the said sources and remaining at rest in connection with one of the contacts; in which device each scanning switch is connected in series with a timing switch arranged to close the circuit through the scanning switch during at least part of the time the scanning switch is at rest and of maintaining the said circuit open while the scanning switch is movng, each scanning switch when moving from one rest position to the next rest postion passing over a programmed whole number of contacts, the number being determined by the kinematic chains connecting the scanning switch to the motive power input; the scanning switch being driven via the drive to the timing switch whereby the operation of the scanning switch is always dependent upon the operation of the timing switch.

When the device comprises two scanning switches and a common timing switch, the two scanning switches are successively and alternately driven and stopped, being electrically inhibited while being driven and electrically activated when stopped, one of the switches being activated while the other is stopped, and vice versa; the two scanning switches can thus feed a same set of external circuits (addresses) according to two different intermittent drive programmes and to two programmes of switching on and off the circuits controlled by the common timing switch.

The device may comprise a further rotary switch provided with brushes which are not identically spaced and which are separated always by a whole number of contact studs, the said further switch being connected in series in the circuit connecting the timing switch and the scanning switch, this further switch and the Scanning switch being both driven from the timing switch which closes the circuits when the two switches are at rest, the said scanning switch likewise having a plurality of brushes separated one from another, by a whole number of contact studs, the path of the scanning switch being divided in such manner that in each of their rest or switch positions the brushes of the scanning switch designate corresponding circuits which are independent of one another. In such an arrangement, the circuits closed by the brushes represent the Boolean product of the two sets of circuits.

In the device of the invention the intermittent driving programme of each scanning switch may be controlled by the timing switch in such a manner that between two successive active switching positions the scanning switch passes over a whole number of contact, the number being determined by the driving programme and being always greater than one; the scanning switch being stopped during the execution of the programme at least once at each of its switching positions.

The aforesaid intermittent drive means may comprise a looped delay line in which every second element stores one term of the programme, allowing variation of the intermittent drive programme.

When a plurality of switches is driven by a single kinematic chain in accordance with a common intermittent drive programme, each switch may have a number of contacts, and therefore of possible rest positions, different from that of the other switches of the kinematic chain.

The invention is described in greater detail below with reference to the accompanying drawings, in which:

FIGURE 1 illustrates diagrammatically a switching device which can be used for the reception and transmission of signals;

FIGURE 2 illustrates in profile the kinematic driving chains of the switches of the arrangement illustrated in FIGURE 1;

FIGURE 3 represents in Cartesian coordinates the movements of the elements of said device;

FIGURE 4 illustrates an alternative form of the device;

FIGURE 5 represents in cartesian co-ordinates the movements of the principal elements of the device illustrated in FIGURE 4;

FIGURE 6 illustrates in elevation the components of a delay line;

FIGURE 7 illustrates in plan an arrangement for controlling four switches according of a variable programme;

FIGURE 8 illustrates the arrangement of FIGURE 7 in elevation;

FIGURE 9 shows the electric diagram of the arrangement of FIGURE 7;

FIGURES 10 and 11 are diagrams of the operation of the arrangement of FIGURE 7.

The switching device illustrated in FIGURE 1 comprises two

scanning switches

1 and 2, a timing switch 9, input circuits 101 to 108, an output circuit 200, and

internal circuits

201 and 202.

This device, which is mentioned solely by way of example, is capable of scanning the input circuits 101 to 108 in accordance with a predetermined programme. The number of circuits illustrated is obviously not a limitation; the

scanning switches

1 and 2 may, alternatively, be provided with further contact studs, which may be designated 11, 12, 13 and 21, 22, 23 extending along their entire circumferences.

In the position illustrated in FIGURE 1, the active circuit is the circuit which connects the input channel 104 to the output channel 200, passing through the stud 14 of the switch 1, the brush 19, the channel 201 of the internal circuit, the semicircular contact 31 of the switch 9, and the brush 39 of the latter.

The device may be so associated with external apparatus that the input channel 104 is connected to a signal source and a signal receiving device is connected to the output channel 200.

The brush 39 of the timing switch 9 is rotated continuously so that, during one half of each revolution the output channel 200 is connected to the brush of one scanning switch while, during the other half revolution, the output channel is connected to the brush of the other scanning switch. The

brushes

19 and 29, of the scanning switches are so driven, intermittently and in co-operation with the brush 39 of the timing switch 9, that the brush of one scanning switch moves only when the output channel 200 is connected to the brush of the other scanning switch. All the switches are driven according to the aforementioned predeterminde programme.

Thus, for each half revolution of the timing switch, one scanning switch is stopped and activated (connected, or on) and the other exploring switch is rotating and inhibited (disconnected, or off).

As long as a

scanning switch

1 or 2 is disconnected, it can pass over any number of studs, to reach the next switching position, according to its driving programme. Thus, the space division switching programme, that is to say the sequence in which active switching positions are reached (which sequence is determined by the intermittent driving programme), is independent of the rate at which the exploration is carried out and the duration of each connection between the input and output circuits (which factors are determined by the time division switching' programme).

When signals to be selected by the scanning operation are separated in time by periods sufiicient to allow the scanning brush to be repositioned between the occurance of two successive signals, a single scanning switch may be used.

FIGURE 2 illustrates the kinematic chains driving the

switches

1, 2 and 9.

The shaft 9a of the timing switch brush 39 is driven by a chain of

elements

500, 519, 519, 509, which kinematic chain comprises the means of executing the time division switching programme.

The shaft 1a of the scanning switch 1 is driven by the elements 509, 511-511, and 501, and the shaft 2a of the scanning switch 2 is driven by the elements 509, 512- 512', and 502. These two kinematic chains represent the component elements of the space division switching programme.

In the example illustrated, element 500 is a driving pinion keyed on the driving shaft of the device, which is driven, for example, by a synchronous motor.

This driving pinion is provided with three

cylindrical stop surfaces

506, 507, and 508, and with three

starting teeth

503, 504, and 505, each tooth having associated therewith an adjacent recess. In this example the pinion 500 may be considered to have twenty-four circumferential divisions and the three starting teeth are so distributed that there are six circumferential divisions between the tooth 503 and the tooth 504, ten divisions between the tooth 504 and the tooth 505, and eight divisions between the latter and the tooth 503.

A driven pinion 519 has twelve circumferential divisions, over which three teeth 529 are distributed which are spaced apart by four circumferential divisions, that is to say situated at in relation to one another, and their stopping positions correspond to zero, four, and eight divisions.

In a second plane the driving pinion 500 has teeth distributed continuously around its circumference, as indicated at 500, co-operating with corresponding teeth '519' on the pinion 519 and situated in the same plane as the tooth 500'. The teeth 519' are removed at points corresponding to the stopping positions of the pinion 519.

One cycle of the movement of the pinion 519 is defined as the movement corresponding to one rotation of the pinion 500; which rotation comprises the twenty-four circumferential divisions of the driving pinion 500-.

The diagram 519 in FIGURE -3 illustrates graphically the intermittent movement of this pinion 519, the absissa representing rotation of the pinion 500 and the ordinate rotation of the pinion 519, both in their respective circumferential divisions. In this example, a cycle of the pinion 519 comprises three equal uniform movements and three motionless intervals, each movement comprising four divisions but the motionless intervals being of different durations, comprising in succession '2, 6 and 4 divisions of the reference pinion 500.

An element 519", toothed over its entire periphery, is solid with the pinion 519 and meshes continuously with a pinion 509 keyed on the shaft 9a of the timing switch 9, the numbers of teeth of the pinion 509 and of the element 519 being in the ratio of 2/ 3.

The driving programme of the timing switch is illustrated at 509 in 'FIGURE 3. A single programme cycle comprises forty-eight circumferential divisions of the reference pinion 500; each movement covers an angle of 1r radians.

The scanning switch 1 is driven via a pinion 501, secured to the brush shaft In, its cycle comprising stopped and driven phases, as shown at 501 in FIGURE 3; the parts of the horizontal lines shown heavy correspond to the times during which the scanning switch 1 is stationary and its bruch 19 is connected to the output channel 200; that is the times when the switch is activated. These activated periods constitute the time division switching programme of the said switch.

Similarly, the scanning switch 2, which is driven by a pinion 502, in FIGURE 2, whose topped and driven phases are shown at 502 in FIGURE 3, is activated during periods only complementary to the activated periods of the switch 501. These complementary activated periods correspond to part of the times during which the corresponding exploring switch is stopped. The pinion meshes with a pinion 511' in the ratio 17 to 12. The switch 1 comprises seventeen contact studs uniformly spaced apart, of which only seven are shown in FIGURE 1.

The pinion 511' is fixedly connected to a pinion 511 and receives therefrom an intermittent movement which is imparted to the pinion 511, via three teeth 521 cooperating with a. single starting tooth 520 of a pinion 509', on each revolution of the pinion 509'.

The sequential space division switching programme of the switch '1 will thus be a sequence of 17 X3=51 terms which in order are:

0, 2, 8, 12, 14, 3, 7, 9, 15, 2, 4, 10, 14, 16, 5, 9, 11, 0, 4, 6, 12, 16, l, 7, 11, 13, '2, 6, 8, 14, 1, 3, 9, 13, 15, 4, 8, 10, 1'6, 3, 5, ll, 15, 0, 6, '10, 1 2, l, 5, 7, 13, 0.

The pinion 502 is keyed on the shaft 2a of the scanning switch 2 and meshes with a pinion 512' in the'ratio 211 to 12.

The scanning switch 2 has twenty-one uniformly spaced contact studs.

The pinion 512' is fixedly connected to a pinion 512 and receives therefrom an intermittent movement, the pinion 512 being driven by four teeth 542, from the starting tooth 520 of the pinion 509'. Between each of their stopped positions the

pinions

511 and 512 are drive by uniform motion pinions, not illustrated in FIGURE 2.

The sequential space division switching programme of the scanning switch 2 is a sequence of 2l1 2=42 terms, the intermittent driving programme of said switch 2 being composed of two terms, namely two and four divisions.

In this example, the product 42x51 yields 2142 states which represent the complete space division switching programme of the two

scanning switches

1 and 2. The complete switching programme of the device is provided by the superimposition of the time and space division switching programmes.

FIGURE 4 illustrates a device in which the scanning switches are connected to the lines and to the columns of a conventional switching matrix 110. The

switches

1 and 2 in FIGURE 4 scan the lines, and switches t3 and 4 scan the columns of the matrix 110, this part of the device being illustrated generally, and only the associated timing switch 9 and its circuits being shown in greater detail.\

Table I below indicates the scanning switches which are activated in dependence on the positions of the timing switch brushes, these positions being repeated twice per revolution.

TABLE I Position Scanning of timing switch switch 9 activated The scanning switch 1 is connected to the contact 91 of the timing switch 9; the scanning switch 2 is connected to the contact 92; the scanning switch 3 to the two contacts 93 and 93'; and the switch 4 to the contact 94.

This arrangement is particularly advantageous for reasons of reliability, because in operation only one scanning switch is moving at one time.

FIGURE 5 illustrates the operation of the device of FIGURE 4. The periods during which each scanning switch is activated by the timing switch 9 are indicated by heavy horizontal lines for the corresponding diagrams 1,2,3, and 4 in FIGURE 5.

In order to enable programming the driving of the scanning switches and timing switch respectively, the intermittent driving kinematic chains providing a constant stored programme are substituted in the device ill-ustrated in FIGURE 4 and just described by mechanical delay lines, such as those described in US. Patent No. 2,978,919. One of the elements of each delay line is fixedly connected to the corresponding switch, so that the delay line can drive the switch according to a programme recorded in the line. After registration of a programme, each delay line is looped on itself during operation, which permits repetition of the recorded programme until a new programme is introduced.

Each of the scanning switches 1, 2, 3 and 4, which receives its drive from the corresponding delay line, may at any moment be in one of the four operational modes illustrated in the corresponding one of the diagrams 1, 2, 3 and 4.

The delay line driving the timing switch 9 receives its drive direct from an input driving shaft constituting the common source of motive power. Each of the delay lines driving the scanning switches 1, 2, 3 and 4 is started from the drive of the timing switch 9. FIGURE 5 illustrates the different resulting movement of the scanning switch driving pinions identified in FIGURE 5 by 501,

502, 533, and 534.

FIGURE 6 illustrates in elevation the elements constituting a delay line constructed in accordance with the prior patent specification referred to above, in which the shafts carrying the pinions 501 and 501' are started by the timing switch 9 when the latter passes through position 4, as shown by the diagram in FIGURE 5.

The delay line comprises a first series of

elements

522, 523 each of which memorises a term of the driving programme, and a second series which comprises similar elements and which is offset by half a row in order to co-operate with two neighbouring elements of the first series, the

second series

512, 513, 514 being then empty. In the course of a first part of the driving of the delay line, each element of the first series transmits a term of the programme to an element of the second series, for example the element 522 to the element 513, the element 523 to the element 514, and so on.

In the course of a second part of the driving of the delay line, each element of the second series returns the term, which it had stored, to an element of the first series (which will hereinafter be referred to as the main series) but with offsetting by one row.

FIGURES 7 and 8 illustrate another example of the switching device, comprising four switches A, B, C, D, which can constitute a programmer. FIGURE 9 shows the electric diagram of this arrangement.

In this arrangement, the timing switch D is fixedly connected to a driving shaft 43 and is connected to serve as a rotary contact breaker, as shown by the diagram in FIGURE 10, during rotation of the switches A, B, C, to ensure that the signals transmitted will always coincide with a defined state of the switching positions. The time division switching programme comprises two alternating terms (the admission of the current), one of a duration of 91 of a revolution of the driving shaft 43 and the other of of a revolution of the said shaft.

The driving shaft 43 is also fixedly connected to a pinion 44, arranged to drive the intermittent gears. The pinion 44 controls the

pinions

45 and 46 alternately as indicated by the diagrams in FIGURE 11.

The driven pinion 45, arranged for a programme, having a single term, advances, for each revolution of the pinion 44, by half a revolution corresponding to two switching positions of the switches B and C, which are driven by the pinion 45 in different ratios. The switch B in fact has three switching positions and its driving ratio is therefore /1, while the switch C has five switching positions and is driven in the ratio 5/4.

The driven pinion 46 is arranged for a programme comprising two terms, the first corresponding to the driving of the exploring switch 1, comprising four switching positions, and the second to a three-posiiton drive. The output signals are transmitted by the scanning switch A having four poles and by the scanning switch B having three poles. Thus 3 4=12 different output signals are obtained which are established as follows:

TABLE II Reference Circuits established byletter for signal A and B I la lb K 1a 3b L 2a 1b R 3a 3b S 4a lb U 4a 3b If it is assumed that the switch C is short-circuited, the switching programme would in this case be reduced to the emission of 4 12=48 signals, that is one of the signals in each rest position. This is equivalent to exploring a conventional matrix in four different ways.

However, the switch C permits the programme of the device to be varied. It can interrupt the circuits in accordance with its own programme. This programme is modified by means of the contactors E and F (FIGURE 9) which have three positions and are controlled manually.

It is thus possible to choose from nine switching programmes, which can be established as follows:

TABLE III Selection of programmes by Circuits established contractors E and F for B through 0 Programmes E on 3c-F on 60.

Because of the driving of the switch A, which alternates in relation to the switches B and C, the switching sequence of the switch A provides for the emission of sixteen signals.

The switching sequence of the switch B provides for the emission of six signals, and the switching sequence of the switch C of ten signals.

The smallest whole common multiple of 16, 6 and 10 is 240. Each programme can therefore be composed of 240 terms.

Table IV below shows: in the first column, the serial number of the signals emitted; in the next three columns the switching positions of the switches A, B and C and in the next nine columns the performance of the nine programmes.

In the three columns indicating the positions of the switches, the actual sequences of the switches are demarcated by horizontal lines.

It may be observed that these limits coincide: every thirty switching positions for the switches B and C (the smallest common integral multiple of 6 and 10) every forty-eight switching positions for the switches A and B (the smallest integral common multiple of 16 and 6) every eighty switching positions for the switches A and C (the smallest integral common multiple of 16 and 10) and only after two hundred and forty switching positions for the switches A, B and C.

TABLE IV Position of Signals transmitted in dependence on programme switches r At A B C P1 P2 P3 P4 P P0 P7 Ps Pr 0 1-...- 141 lb 2 la 3b 3c 3-.-..3a 3b 3c 4....-30. 2b 5c 5- 2a 2b 5c 6.--.- 211 lb 20 L 10 7..... 4a lb 20 S 8---.-411 3b 40 U 9--...- 3a 3b 46 R 10....3a 2b 10 P P P P P P P P P 11---.1a 2b 10 J .l' I J J J J I .T 12-..- 1a 1b 3c I I I 13-.--441 1b 3c 14---. 4a 3b 5c 15--.. 2a 3b 5c 16-... 2a 2b 20 2b 2c .T J I 18...-1a 1b 4c I I I 1b 4c O O O 3b1cRRRRRRRRR SblcNNNNNNNNN 2!) M M 2!) T T 1!:

lb 50 3b 20 3b 20 2b 2b 40 lb 10 2a 1b 10 L 2a 3b 3b 2b 2b 1b 1b 20 3b 40 3b 4c 40---. 4a 2b 10 T T T T T T T T 41...-3a 2b is P P P P P I? P P P 4 42.... 3a 1b 3c O O O 43--.- 1a lb I 44-.-- 1a 3b 45-.--4u 3b 46-.-- 4a 2b 47----211 2b 48--..2a 1b 45 49-...1a 1b 4c I I I 50...-la3b1c K K K K K K K K K 51.-.-3a3b1c R R R R R R R R R 2!; P 2b M 111 L 1!] S 3!; 3b 2b 2b 1b lcMMM 10 T T '1 3c S Pa P TABLE IV'Continued Signals transmitted in dependence on programme P2 Pa P4 P ii"IIIIIIIIIII Position of switches At A B 0 P1 177--- 1a 3b 178 1a 2b 4c 179-.. 3a 2b 4c 180 3a lb Pa P0 TABLE IV- Con'tinued Signals transmitted in dependence on programme P3 P4 P5 P0 Position of switches At A B 0 P1 P2 660666 6066 0 868666 CC 0000 133552 2441 355224 41 1335 .Dbbbbb Db-Db .0 bbbb '0 0b Obbb 133221 1332 2 1332%1 -13 90221 aaaaaa a CCCC CC C COCO CC CC 6666 C6 Ubbb .Db .Obbbbb Ub .Db Ob-Ubbbbb 1332 21 133221 1.3 32 21133221 aaaa aa a aaaa aa a aaa 789% 00 OMOOOO W1 1m mnmwlmmww 9 91 11 111.111 1.1 1.1 11111111 J I I I .0.D.D.D .Dbbbbb 3221 133221 The examples described make it clear that the invention provides for the separation of the means effecting the time division switching programme from the means effecting the space division switching programme.

L 4c N bb DLU .D-Dbbbb .Db .Dbbb 32 211 133221 13 3221 It is seen that as the result of this feature and through the selection:

(1) of the number of switches; (2) of the number of poles of each of the switches;

(3) of the connection diagram,

by means of the device of the invention it is possible to provide different and variable switching programmes.

What is claimed is:

1. In a sequential switching device capable of storing and operating according to a programme comprising a plurality of rotary switches connected to a common motive power input by kinematic chains comprising unirform motion drive means and intermittent drive means, at least one of the switches having contacts for electrical connection to corresponding external signal sources and being capable according to the said programme of alternately moving to act as a scanning switch for exploring signals from said sources and remaining at rest connection through one of the contacts; a timing switch, electrical connection means connecting the timing switch in series with each rotary switch, the timing switch arranged to close the circuit through the scanning switch during at least part of the time the scanning switch is at rest and of maintaining a circuit open while the scanning switch is moving, kinematic chain means driving the timing switch from said common power input, and kinematic chain intermittent drive means driving each rotary switch from the timing switch so that it is successively at rest on one contact and moving from one rest position to the next rest position, passing over a whole number of contacts determined by the kinematic chains connecting the scanning switch to the motive power input.

2. A device according to claim 1 comprising two scanning switches and a common timing switch; electrical connection means connecting corresponding contacts of the scanning switches together to form pairs for connection to the said signal sources; and separate kinematic chain drive means drivably connecting each scanning switch to the timing switch, the various drive means cooperating so that one scanning switch is at rest and, in use, connecting with a signal source, while the other is moving and is disconnected from the timing switch.

3. A device as claimed in claim 1 comprising at least one scanning switch having rotary mounting means, a plurality of brushes mounted on the said mounting means, adjacent brushes being separated by a distance corresponding to a whole number of contacts, the brushes being so spaced that, in each rest position of the scanning switch, the brushes will be connected to circuits which are independent of one another; a further rotary switch having rotary mounting means and a plurality of brushes mounted thereon, the brushes being unequally spaced, adjacent pairs of brushes being separated by distances corresponding to a whole number of contacts; and connection means connecting the further rotary switch in series between the timing switch and the scanning switch.

4. A device according to claim 1 wherein the said kinematic chain intermittent drive means is so arranged that there is a plurality of predetermined rest positions on the scanning switch, the scanning switch moves over a plurality of contacts between adjacent rest positions, and the scanning switch stops at least once at each of the said rest positions during the execution of the programme.

5. A device according to claim 1 wherein the said intermittent drive means comprises a mechanical delay line looped back on itself and having a plurality of sequential elements, every second element being capable of storing a term of the programme so as to permit varying of an intermittent drive phase of the programme.

6. A device according to claim 11 comprising at least two switches having different numbers of contacts, and a common intermittent kinematic drive chain arranged to drive the switches.

References Cited UNITED STATES PATENTS 2,568,906 9/1951 Williams 20038 2,57 9,983 12/ 1951 Thornton 200-38 FOREIGN PATENTS 999,510 7/ 1965 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner.

US. Cl. X.R. 307-41