US2349849A - Gas tube relay circuits - Google Patents

Description

May 30, 1944. H. B. DEAL 2,349,849

GAS TUBE RELAY CIRCUIT Filed March l5, 1942 INVENTOR /90//770/75 a/ Patented May 30, 1944 :Maus

oas 'was naar cnwurrs naman a. ma. cien anice. N. J., mmm t Radio Corporation of Ameri of Delaware ca,aeorporatlon Application March 13. 1942, Serial No. 434,510

:Claima My present invention relates to gas tube relay circuits, and more particularly to relay control circuits utilizing a low! pressure gas tube of the cold cathode type.

One of the main objects of my present invention is to improve generally the simplicity and reliability of relay control circuits, and more especially to provide a relay control circuit employing a gas triode whose discharge i; dependent upon the division of voltage across a potential divider connected between the-plate and cold cathode of the triode and across the source of energizing voltage.

The novel features which I believe to be char acteristic of my invention are set forth with particularity in the appended claims; the invention itself, however, as to both its organization and method ci operation will best be understood by reference to the following description taken in connection with the drawing in which I have indicated diagrammatically several circuit organizations whereby my invention may be carried into effect.

In the drawing:

Fig. 1 shows a circuit embodying my invention, the voltage divider being generically represented,

Figs. 2 to 5 inclusive illustrate respectively different modications o f'the potential divider,

Figs. 6 and 6a show two further types of potential dividers,

Figs. '1 and 'la illustrate two additional forms of potential dividers.

Referring now to the accompanying drawing, wherein like reference characters in the diiierent figures designate similar circuit elements, vthe tube i is generally an ionic-cathode, glow-discharge tube. It contains a plate, or anode, 1', a grid, or starter anode, 3 and a cold cathode l. The tube, as shown, is a gas triode of the OA4-G type. The electrodes are sealed in a bulb filled with an inert gas or vapor at reduced pressure. The invention is not restricted to this typeoi'f cold cathode relay tube. Indeed, any cold cathode gas tube may be utilized, so long as the plate is enabled to carry current upon discharge occurring in the tube in response to the control electrodel 3 assuming a striking" potential.

The energizing voltage source, shown by way of illustration asv of 110 volts and 60 cycles,'feeds lines 5 and 6. The cathode l is connected to one side of the energizing system, say line i. The line 5 is connected to plate 2 through the winding of electromagnet relay l. Condenser I, across the relay winding, acts as a smoothing condenser. It helps to hold the relay armature in the actuated,

or closed. position without chattering. The armature of the relay is denoted by numeral 9, and is normally spring-biased out of contact with the switch contact i0. Hence, closure of switch S-I 0 completes any desired type of controlled circuit. Thus, the controlled circuit may include a lamp, bell, alarm or indicator; or it may be any control device which is to be actuated upon energization of relay 1 to close switch Ill- 9. For example, amotor to start a heating system may be controlled.

'.I'he control circuit comprises a.potential divider Z-Z' connected between the lines 5 and i. The control electrode is connected by lead I'i, preferably terminating in an adjustable tap, to any desired point along the dividerl Z-Z. The latter, from a generic viewpoint, consists of a pair of impedances adapted to develop thereacross a potential difference. 'I'he nature of the impedances, the magnitude thereof, and the positioning of tap Il will determine the "striking.

point oi' the gas tube. In normal operation of the' tube I, a relatively small amount oi electrical energy supplied to the control electrode, or starter-anode, 3 initiates a glow discharge between cathode 4 and electrode 3. This discharge produces positive ions which assist in initiating the main discharge between cathode and plate 2. The plate current, flowing during the cathode-to plate discharge, energizes the winding of relay 1 thereby to close switchv I 0 9.

'The tap il, regardless of the nature of the divider impedances, is adjusted to a point such that the starter-anode 3 is maintained at a potential just below that required for break-down. Since the striking potentialv of the tube I is obtained irom the division of line voltage at the divider Z-Z', any control that will change the division of the voltage will strike the discharge between cathode and electrode 3. This will, in turn, release the discharge to the plate 2 which carries a heavy currentv supplied by the power line. Hence, the switch. IO-S will be closed to complete rthe controlled circuit. The particular virtue of this invention is the negligible (or for a capacity divider, zero) power consumption in the stand-by, or non-actuated, condition. Filament types of gas or hard vacuum tubes have been used, but they all require continuous power consumption to the amount of several watts. If the divider resistance is of the order of 1,000,- 000 ohms the power consumption is of the order of milliwatts. Divider resistances of many times this value are feasible, so that the power consumption may be in the orde;` oi' microwatts.

which restores the temperature.

In Fig. 3 the divider consists oi' series con-'- densers C-Ci. The tap II is adjusted between the condensers. The upper capacity Ci could be, for example, a liquid level device whose capacity depends on the height of a body oi' liquid. It is then arranged that as long as C and C1 have a 'deilnlte magnitude relation, the voltages thereacross will be such as to maintain the electrode 3 just below the striking" potential. Upon condenser Ci undergoing a change in capacity to change the voltage division the tube I will have a discharge to the plate 2. In Fig. 4 it is shown that capacities C-Ci may be replaced by inductors L-Li respectively. Of course, either section of the divider may be the variable section.

In Fig. 5 the divider consists of a resistor R in series with the output element M of a sound pickup device, such as a microphone. For example, in sound detection work theoutput element M is arranged to cooperate with resistor R to prevent dischargeoi tube I in the absence 'of sound. A predetermined change in voltage division across R-M results in setting of an alarm device in the controlled circuit.

In Fig. 6 there is shown a potential divider P of resistor form; a selenium cell is connected between the line 5 and tap I I. As is well known, the selenium cell is a device whose resistance varies with light falling thereon. In the position shown, the balance of P (after proper adjlmtment for balance by tap Il) prevents ignition of the gas tube for the then-prevailing illumination of the cell. Any increase of light intensity at the cellin eilect raises the 60 cycle voltage dierence between the starter-anode and cathode thereby causing dis'- charge to the plate 2.

Similarly, and as shown in Fig. 6a, for'another setting of tap II and the positioning of the selenium cell between tap I I and line 6, a voltage just below that on the control electrode which will initiate a discharge is found, under the then-prevailing illuminationoi the cell. In this caseany decrease of illumination on the selenium cell will initiate a gas tube discharge thereby closing th relay switch Ill-9.

In Fig. '7 there' is shown a circuit wherein a photocell 20 replaces the selenium cell of Fig. 6. The photocell may be of the gas or hard vacuum types. The divider P has its slidable tap II arranged in series with a resistor 22 of'about 25 megohms. The resistor 22 has shunting it the Aphotocell in series with a resistor 23. 'I'he resistor 2 I, of about 20 meghoms, connects the electrede end of resistor 22 to line 6. In Fig. '7a the photocell is connected'across the resistor 2|. The latter is the dark-actuated position of the photocell.` as in the case of the selenium `cell in Fig. 6a. The potentiometer P is adjusted by tap Il to its critical setting such that an increase in illumination of cell 20 initiates discharge in the tube I in the case of Fig. v'1, whereas la decrease in illumination causes the tube I to discharge in the case of Fig. 7a. Diminlshed sensitivity can be had l ance is in parallel with ari element of the resistance divider. If the photocelLresistance changes,

due to a change in illumination upon it, the resistance `divider ratio is upset. and the trigger anode can then ignite the current-carrying discharge. The extra resistances in Figs. 'l and 7a represent an actual working instrument. The ranges of resistance variation in the photocell are very high between light and dark. The additional series and shunt resistances hold these variations within limits so that impractically large divider variations are not required.

Once a gas tube is ignited, there must be a reduction of voltage to a value below the gas extinction de-ionizing voltage, to shut it oil preparatory to the next ignitionvcycle. For alternating current this extinction is attained twice each alternation when the line voltage is momentarily zero. For direct current (or battery) operation, this maybe done manually, or with a circuit interrupter or by other automatic means, as for example a blocking (motor boating) network associated with the gas tube.

While'I have indicated and described several systems for carrying my invention into eilect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular organizations shown and described, but that Vmany modifications may be made without departing from the scope of my invention, as set forth in the appended claims.

What I claim is:

l. In combination with a source of alternating current energizing voltage, a potential divider consisting of pure resistance thereacross, a gas discharge tube including a cold cathode. a plate and a starter-anode, a controlled circuit including control means-arranged in circuit with the plate, means connecting the cathode to plate path of the tube across said source whereby extinction of the gas tube ignition is attained tw'ice each alternation'when the alternating source is momentarily zero, and means free of impedance connecting said starter-anode to a predetermined point of said divider such that said starter-anode is just below the strikingvvoltage of said tube and said divider having such a relatively high resistance magnitudevthat the power consumption v of the gas tube in non-ignited state is negligible. 2. In combination, in a relay control circuit, a controlled circuit including as an element thereof a switch device, a relay for controlling said switch, a gas tube provided with at least a cold cathode,

`a plate and 4a control electrode, a pair of alter- 'charge between cathode and plate, and said divider having a section thereof whose resistance is subject to variation such as to change the volt-d age division across the divider and said divider having a resistance magnitude of the order of one million ohms Athereby to'reduce the power consumption of the tube in non-ignited state to a negligible value.

3. In combination with a source of alternatingl current energizing current, a potential divider comprising pure resistance thereacross, a gas discharge tube including a cold cathode, a plate and a starter-anode, a controlled circuit includtwice each alternation when the alternating source is momentarily zero, and means lsubstantially free of impedance connecting said starteranode to a predetermined point of said divider such that said starter-anode is Just below the striking voltage of said tube, and said divider having a resistance magnitude oi' at least one million ohms thereby permitting said tube 'to consume negligible power from said source in the l0 open" condition oi the control switch.

HARMON B. DEAL.

Images