US2534299A - Electronic timer - Google Patents

Description

Dec. 19, 1950 A. J. RUIZ ET AL ELECTRONIC TIMER 92w m 5 "f m 3 11+ l|l.|| w v W J m 5 u m a m w m 5 a mm W m \N v 5 M06 M 2 w 4 J Z ZEHZ Wm w z m 2 z 9 & LT 1 g 8 2 w. 5 m w a FM FF m 1 Patented Dec. 19, 1950 UNITED STATES PNFENF @FFl-EE ELECTRONIC TIMER Autism? Ruii'obmus ohr stL Jrx; anaeugelie' J. Kama-ck; UnitedStat's' Na'vy Applicationluly'il'; wisgseriai- No. 60 1;002?

(crate-27)" (Granted under th'e act or: 31-1883, as? amended Aipril'sgil, 192s; euro. @1757):

6. claims:

This invention relates to I electronic timers i of the type" providing periodic switch" actuation. The invention utilizes a-thermionic tube adapted te periodic'ally become conductive and substantially' non-conductive at aj; rate de'termined' p'rimaruy by the heating and'eaoiingumes fo'r 'the' cathode of thetube;

An object of the invention is to providea sim pie; lightweight an inexpensive timing device whichis' adaptable to intermittent circuit control; sii'ch' as ar flashing-signal control: I

Timing device's known" in' the art 1 are subject to" various limitations and disadvantages; The system according to tlfis invention uses negligible power, is capable of controlling relatively large loads; is' lightin weight, small; simple;- and: inexpensive; retains the origina1 setting'; may: be readily adjusted' to produce equal on"" and: "on" per-ides or? other conditions; ahd is operative: on alternating or direct current oi various voltages with little or no modification. 'l'lie ope'rationof this invention depends? upon theiperiodicx a'ctiiatitanoi a relay in: accordance. with changes" in conductance of a thermionic tube; the changes-in conductance'being initiated by? changing thefre sistance' in the: heater circuit of. the". tube by the userof: a switch comprising? aipar-t of the" relay. v

Further objects and advantages of the: invenftio'rrwill tie? apparent from the following descrip e tioni. when.- taken. in: conjunction with the v drawings,. of2?wh'ich:

Fig; 1 ises. diagrammatic? view of: the preferred embodiment of: a timer: according to the: invenman; and

Fig: 2 is -az-dia'grainmaticiview of a modification :2

of the. timer: of the":inventionrasrapplied to blinking running lightsi on an aircraft:

The timer of: the invention shown': in; Fig; 1' comprises a thermionic diode tube It! and a double' pole" and: double throw. relay including; a'i-lsolenoid' actuating coil Hi and. movable contacts: l2- and? I3; Anode- I41: of: diode tube In is: connected through? coil' Hi to: OIIBZD'OWGFSUPDIY? terminal t5; and cathode l1 isfconnec'tedt-td the" other power supply terminal l fixthroughia resistor I9; Power v for these. terminals may 'be alternating current", or it: maybe' direct'current. Ifdii ect current is used; terminal l6 should be negative" and I5 should. be' positive in potential; causing: a positive potential tubeapplied to-anode'I l; Heater fila' ment [B of the tube is connected at one end through currentlimitin'g resistor [9 to terminal Hi, and at the other end to stationary contact 20 and through' a resistor 231 to stationary contact 22? Mdvablei contactwv I2 is; in engagement with 2: stanonary centacezt w enme relay is in dropped out 'or deenergize'd position to pr'ov'ide current for the =fi1ameiit iiom terniinal l through conductor 2 3 mavens contact l-'2,'.- stationary contact 29';

rnina'lIii;- W-he'n the relay-pick's up or is energ'i'zedi a siifistantially reduce'd current is provided through stationary contact conductorfi; and resistor 21; the resistor serving to limit the current to a-' value-less than norma'l rated'heater filaiment current forthety-pe' oi tub'e used. A condenser 21 is connec'ted in parallel with: solenoid c'oil H, and a variable-resistor 28'" is connected fro'ln a'nod'e M'to conductor 25t'o act as a short circuiting resi'stor' across condenser 21 when the relay s picl ed up.-

Additional stationary contacts 29 and 30 are shown adapted to be-engaged by movable contact I 3 to control an external" circuit.

Iii operationwhen power is applied to term'inals I5 and" I6; substantially rated current flows through filain'ent I 8', the" currentibeing limit'e'dby'; resistor l9'*to the rated value. Of course, if substantially rated filament voltage is'applied to te'rminal's l5 and I6; resistor lfilmay be omittedi As the cathode I! is heated by the filament to emissive temperature, tube lilbecomes conductive causing a current to flow from terminal l5 through c'oill Ito anode [4; As the conductance becomeshighen the' current increases until the r'elay'picksup; Ifthe power supplied'is alternating current', itwill b'e rectified'by the action of the tube; consequently; only unidirectional current will flow'through' coil H; whether a direct or alternating current sourceis" provided. Condenser 21 will become charged to the potential appearing across c'oil l I as thetcurrent'increa'ses. When the relay picksup; engaging. movable contact l2 with stationary contact 22; the filament connections are. changed by the insertion. of an additional filament current limiting resistor 21 which reduces the filament" current-to a value insufficient to maintain the cathodeat emissive temperature; A'sthe cathode coolsy-the' conductanc'eor the'tube is decreaseduntil, after" a period of time; the current through: thetub-e decreases to 1 a value insufficient to maintain the picked-up condition of 'the relay. The-condenser discharges through the relay coil as the current through I the tube decreases to maintain the relay picked-up until the" tube current is considerably" less than hold-iricurrenti f'orthe relay. Variable resistor zfl may be providedto adjust the'discharge time of? the condenser 21 a low resistance value for resistor" 28 causing: more rapid" drop-outof; the

relay. The inclusion of resistor 28 is not essential to the proper operation of the invention, however, merely furnishing a convenient and novel control device for the timer.

The choice of a tube to use in the timer will depend primarily on the time constant desired and to a lesser extent on the voltage, the current requirements of the relay coil, cost, ruggedness required, and whether alternating or direct current power is supplied. It has been found as to the time constant that a period for the on-off cycle as low as one-eighth of a second will result from the use of a filamentary cathode tube of the type designed primarily for battery operation in which the mass of the filament is very small and the filament may be quickly heated and cooled,

whereas a tube with a separate, relatively heavy cathode of the type requiring 117 volt alternating or direct current as a filament supply may give a time cycle of 4 or 5 seconds or more. By proper- 1y selecting the value of resistor 19, substantially any type of thermionic tube with a filament acting as a heater for a thermionic emissive surface, and with an anode, may be successfully utilized, and a different time cycle may be obtained by using a different type of tube. The capacity of condenser 21 will also effect the time constant to an important extent.

Fig. 2 discloses a modified arrangement of the device described as applied to the control of blinking aircraft running lights. A tube In is shown of a type provided with a control grid, a suppressor grid and a screen grid, the control and suppressor grids being connected to the oathode l'i, and the screen grid being connected to the anode Id in a well known manner to cause the tube to act as a diode. The circuit is substantially the equivalent of that shown in Fig. 1, except that additional connections are shown from stationary contacts 29 and 30, respectively, to the ioraand-ait and wing tip running lights of an airplane, being so arranged that when relay contact i3 is dropped out into engagement with contact 2!! current is provided from power terminal l5 through conductor 23, movable contact i3, stationary contact 29, and conductor 34 to the fore-and-aft lights 33 and thence through conductor 36 to power terminal 16, Whereas when the relay picks up movable contact it into engagement with stationary contact 30 current is provided through conductor 35 to the wing tip lights 32 and thence to conductor 36 and terminal [6. As previously explained, the relay picks up and drops-out at a constant rate While the timer is operative, which in this case will cause first the iore-and-aft lights to come on, then go off as the Wing lights come on, the cycles continuing indefinitely at the constant rate determined by the timer of the invention.

If it is desired to increase the anode-cathode potential of the tube in either Fig. 1 or Fig. 2, the potential drop in resistor l9 may be eliminated by connecting cathode ll directly to power terminal l6 instead of to the filament end of resistor I9. Alternatively, resistor is may be omitted by connecting the filament and cathode directly to terminal l6 and inserting a suitable filament current limiting resistor in series in conductor 24.0r in series between conductor 23 and movable relay contact 12.

The timer is particularly adapted to aircraft applications because of the light weight, the sturdiness, ease of adjustment, and small power requirements of the device, and because the time periods remain substantially constant through atmospheric temperature or pressure changes. Ordinary dirt and moisture will not affect the operation of the timer. The device is also adaptable to the control of blinkin signal lights at sea or ashore or to the control of an electrical circuit for many other types of signalling or other apparatus where it is desired to alternately make and break one or more circuits at a constant rate. The timer may replace motor-driven cam-operated switches and. similar equipment at a saving in cost, weight and simplicity, and with more reliable and accurate operation.

It is immaterial to the practice of this invention whether the cathode of the tube comprises a separate sleeve surrounding the filament or constitutes the electron emissive surface of the filament itself. Thus, the cathode shown as element I! in Fig. 1 may be a sleeve type indirectly heated cathode connected externally to one terminal of filament E8 or the element I! may be the surface of the filament and form a part thereof. It is to be noted that wherever the term cathode is used in the appended claims, it e term is intended to cover either type of ther mionic emissive surface, either an indirectly heated sleeve or the directly heated filament surface.

While we have shown a particular embodiment of our invention, it will be understood, of course, that we do not wish to be limited thereto, since many modifications may be made, and we, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of our invention.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes Without the payment of any royalties thereon or therefor.

What is claimed is:

1. An electronic timer comprising a thermionic tube having an anode and a cathode with a heating filament, a relay connected to the anode and responsive to changes in the conductance of the tube, a two contact switch operated by the relay, each contact being included in a separate circuit including the filament, one circuit including a resistance, and a condenser connected in parallel with the relay, and the condenser and relay in parallel being connected in series with that one of the filament heatin circuits closed by the corresponding switch contact, the said relay switch circuits alternately increasing and decreasing the conductance of the tube by respectively heating and cooling the cathode, and the condenser causing the operation of the relay to lag behind changes in the conductance of the tube.

2. An electronic timer comprising a thermionic tube having an anode, a cathode, and a heating filament for the cathode, a relay connected to the anode and responsive to changes in conductance of the tube, switch means operated by the relay and including electrical circuits opened and closed thereby, one circuit including a resistance in circuit with the heating filament, another of said circuits including only the filament, the two circuits being alternately closed and opened for alternately increasing and decreasin the conductance of the tube by respectively heating and cooling the cathode, a condenser connected in parallel with the relay for causing a lag in the relay operation, and a variable resistance connected in the said resistance circuit and to the anode connection of the relay for adjusting the discharge time of the condenser to vary the la thereof.

3. In an electronic timer, a thermionic tube having an anode and a cathode, a relay connected to said anode and responsive to changes in the conductance of said tube, a source of energy for heating said cathode, a circuit including a resistor connectable between said source and said cathode for supplying energy from said source to said cathode, and switch means actuated by said relay for connecting said circuit between said source and said cathode.

4. In an electronic timer, a thermionic tube having an anode and a cathode, a relay connected to said anode and responsive to changes in the conductance of said tube, a source of energy for heating said cathode, a pair of circuits connectable between said source and said cathode for supplying energy from said source to said cathode, one of said circuits including a resistor, and switch means automatically operable upon energization of said relay for connecting said one circuit between said source and said cathode, and upon deenergization of said relay for connecting the other of said circuits between said source and said cathode, whereby the conductance of said tube is alternately increased and decreased to thereby alternately actuate and deactuate said relay.

5. In an electronic timer, a thermionic tube having an anode and a cathode, electromagnetic means connected to said anode and responsive to changes in the conductance of said tube, a source of energy for heating said cathode, a first circuit connected between said source and said cathode for supplying a predetermined amount of energy to said cathode, a second circuit including a resistor connectable between said source and said cathode for supplying a smaller amount of energy to said cathode, said smaller amount being insufiicient to maintain said cathode at emissive temperature, and switch means responsive to the energization of said electromagnetic means for simultaneously breaking said first circuit and completing said second circuit.

6. In an electronic timer, a thermionic tube having an anode circuit and a cathode, electromagnetic means connected in said anode circuit and responsive to the current fiow therein, a source of energy for heating said cathode, first circuit means connectable between said source and said cathode for supplying to said cathode an amount of energy sufficient to maintain a current How in said anode circuit which will energize said electromagnetic means, second circuit means connectable between said source and said cathode for supplying to said cathode a smaller amount of energy than the first-named amount, said smaller amount being insufficient to maintain the current flow in said anode circuit necessary to energize said electromagnetic means, and switch means responsive to energization of said electromagnetic means for simultaneously connecting said second circuit means and maintaining said first circuit means disconnected, said switch means being operable to connect said first circuit means and to maintain said second circuit means disconnected when said electromagnetic means is deenergized.

ALFONSO J. RUIZ. EUGENE J. KUPJACK.

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

UNITED STATES PATENTS Number Name Date 1,738,299 Kille Dec. 3, 1929 1,751,374 Waltemuth Mar. 18, 1930 1,903,420 Badma Apr. 11, 1933 2,028,338 Le Bel Jan. 21, 1936 2,129,747 Sorenson Sept. 13, 1938 2,143,501 Snyder Jan. 10, 1939 2,221,867 Feingold Nov. 19, 1940 2,256,117 Kelley Sept. 16, 1941 2,256,802 Feingold Sept. 23, 1941

Images