US2491858A - Control switch for electric discharge lamps - Google Patents

Description

Dec. 20, 1949 T. HEHENKAMP ETAL 2,491,353

CONTROL SWITCH FOR ELECTRIC DISCHARGE LAMPS Filed April 26, 1947 FIB. 2 I7 I;

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Patented Dec. 20, 1949 CD T L S I FOB ELECTRIC. ISCHA LAMPS Theodorus Hehenkamp andKlaas de Jong,'Eh1d-. hoven, Netherlands, assigncrs'to General Elec-L t -Com an a ec no ticn f e lin Application 'April'zfi, 1947, Serial 'No. 744,06g In-the Netherlands June-27,1946 I 8 Cl ims 3 5:100)

This invention relates to an electric discharge device of the type employing ionizable mediums, such as gases or vapors, and more particularly to control switches for starting and operating electric discharge lamps.

Switches now in wide use with filament .lamps are provided with means for heating the filamentary electrodes and for impressing a high voltage for a short duration upon the electrodes for starting an electric discharge therebetween. Means are provided in such switches to delaythe application of the high voltage until the elec: trodes have reached the desired, electron emit+ ting temperature. When the discharge lamp does not ignite for some reason or other, the ignition arrangement continues its attempts to start the device. Usually the incapacity for starting is due to the loss of electron emission from one or both of the electrodes which may result from dissipation or other loss of activating material on which the emission depends. The large current, which then occurs on repeated starting attempts, is detrimental to the parts of the ignition arrangement and of the lamp in:- stallation. The continued flickering of the lamp due to the unsuccessful attempts of the starter to start the lamp produces light flashes undesirable for lighting purposes.

An object of our invention is to provide a new and improved time-delay lock-out switch.

Another object of our invention is to provide a new and improved starting and operating switch and circuit embodying means whereby after a limited number of unsuccessful attempts to start a lamp the starting operation is discontinued automatically.

A further object of our invention is to provide a starting and operating circuit comprising a switch embodying means for discontinuing the starting operation of the switch under abnormal conditions and which, upon deenergization is automatically restored to a condition for normal operation.

A still further object of our invention-is to provide a new and improved time-delay lock-out switch which will operate as efiectively on direct current as on alternating current installations.

Further features and advantages of our invention will appear from the following description and species thereof.

For a better understanding of our invention reference may be had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended m F res a di erammatic lewshowing the-control switch connected together with a; discharge lamp in an operating circuit. Fig. 2 illustrates diagrammatically a modification of the control switchv shown in Fig. 1. Fig. 3 illustrates diagrammatically another modification of the control switch shown in Fig. 1. Fig. 4 illustrates diagrammatically a modification of the control switch shown in Fig. 3.

Referring to. Fig. 1, the dischargedevice I therein comprises an elongated tubular or cylindrical envelope. 2 having sealed into the ends thereof thermionic electrodes 3 and 4 which may be of the filamentary type each herein illustrated as comprising a coil, preferably in the form of a coiled coil of tungs'tenwire activated with the usual mixture of barium and strontium oxides. The envelope 2 contains an ionizable medium. Thisionizable medium may comprise a rare gas like krypton, neon, argon ormixtures thereof at a pressure. of a few millimeters and a small quantity of mercury which, during operation of thelamp; has a low pressure of the order of ten microns. The device I-may be a low pressure positivecolumn lamp of the fluorescent type with a suitable phosphor which under the influence of radiation from an electric discharge through the .ionizable medium produces fluorescence.

In accordancewith ourzinvention the device I is connected across a suitable power supply'circuit 5, 5, which for example may be a 118 volt, cycle source, for supplying current to device I through the usual ballast 6 which serves as a starting inductance. A manual make-and-break control switch I may be used to connect device I to the power supply. We provide in seriesrelation with'the electrodes of device I or connected in parallel with the discharge path between electrodes:3 and 4, means comprising a parallel circuit,. one branch-of which includes in series relation a. substantiallyinstantaneously operating starting'switch element and a time-delay or lockr-out ithermaliswitch element, and the other branch: of which comprises actuating means for these: elements, which actuating means may be constituted byseparate means or a single unitary means. Astarting and operating circuit 8, 8' comprising a parallel circuit, including two branches inseries with the thermionic electrodes 3 and .41of device I, may include a starting switch 9:and a time-delay lock-out switch II]. The startin Switch-9, forexample, may be an electromagnet ignition; arrangement provided with a magnetic actuating coil or winding II and a starting element suchas an armature I2 provided with a contact memberv I3 for engagement with a counter contact member I4. When the armature is not energized contact members I3 and I4 are held apart by means of a spring I5 tending to rotate the armature around the pivot point I6. The delay lock-out switch I comprises a timedelay element such as a bi-metal strip I1, provided with a contact member I8 which normally is in engagement with a counter contact member I9 while in the inactive or cold condition. A heating element 20, positioned in heat transfer relation with the bi-metal strip I'I, serves as an actuating means for the delay lock-out switch Ill.

One branch of the parallel circuit forming part of the starting and operating circuit 8, 8' contains the winding II in series with the heating element 20. The other parallel branch of circuit 8, 8' contains the armature I2 in series with the bi-metal strip IT.

When the entire installation is energized by closing switch I, current flows through the ballast B, thermionic electrode 4, winding II, heating element 20, and thermionic electrode 3. The winding II actuates the armature I2 substantially instantaneously so that the contact members I3 and. I4 engage each other and thus short circuit the parallel branch embodying the winding II. The branch of the winding II is deenergized and the current limited by the inductance 6 flows through the thermionic electrodes 3 and 4. The de-energized winding I I now releases the armature I2 and reduces the current flowing through the thermionic electrodes 3 and 4, and also rapidly reduces the current through the inductance 6. At this point the thermionic electrodes 3 and 4 are sufficiently heated to support an electrical discharge therebetween, and the induced voltage supplied by the inductance 6 initiates an arc discharge between the electrodes. When the discharge has taken lace, the voltage between the electrodes 3 and 4 drops to an operating voltage, as for example 60 volts. The winding I I is so designed that the current which passe-s at this reduced voltage, through the winding does not attract the armature I2 to the degree necessary to close contacts I3 and I4.

When the device I does not ignite at the first opening of the contacts I3 and 14, the armature I2 is attracted anew, the contact elements I3 and I4 close again, and allow a suitable current to flow through the electrodes 3 and 4 and open again upon de-energization of winding II. This action is repeated so long as the discharge device I does not ignite.

If the device I refuses to ignite after repeated ignition attempts, the bi-metallic strip I I becomes heated by means of the starting current flowing through element 20 and bends in an upward direction so that the contact members I8 and I9 of the delay lock-out switch I0 separate. Element 20 keeps these contacts in open position until the device is disconnected from the power supply 5, After interruption of the power supply heating element 20 cools and allows contact members I8 and I9 to re-engage each other.

The heating element 2!) and the bi-metallic strip I! are so matched with each other that the actuating effect of the heating element 20 upon the bi-metallic strip I! takes eifect only after repeated attempts by the discharge device I to ignite. Adjustment of this type may be obtained by varying the distance between element 20 and member I'I, varying the medium between them, or by varying the contact pressure between contact members I8 and I9. Heating element 20 may be of any suitable type, for examplega resistor or as illustrated in Fig. 2 a small glowdischarge tube 2I. In either case the eatin element 20 may be designed to act as a source of light at well as heat, and thereby act as a signal to warn that the installation is energized and that the delay lock-out switch is in operation.

As has already been indicated, the ignition arrangement may be adjusted to the discharge device I in such a manner that the winding II does not attract the armature I2 after the discharge tube has ignited. After the discharge device I has ignited the current through the branch including the magnetic winding II is lower than when the tube has not ignited. Arrangements can be made to reduce the current through the branch of the magnetic winding II to zero while device I is operating. If the current flowing through the branch including the winding II, when the discharge device I is operating, is large enough it may cause the delay lockout switch to operate. This will have the result that, when device I is operating, contact members I8 and I9 will be separated by heating element 2!]. This is permissible; however, in some cases it is desirable to replace a disconnected device or lamp immediately. In which case the look-out switch I0 Will cause a delay until bimetal strip II cools. It is therefore advantageous to match the heating element 20 and the bimetallic strip I! so that strip I'I will be actuated by means of heating element 20 only by a current larger in value than that passing through the branch including the winding II while device II is operating.

It is particularly advantageous to use the winding II as the heating element 20. Thus the winding II may serve a dual function. According we provide, as illustrated in Fig. 3, a modification of the control switch shown in Fig. 1 wherein the winding II serves also as the heating element. The bi-metallic strip I1 is mounted along side the cylindrical spool of the magnetic winding II. As soon as the spool reaches the required temperature the bi-metallic strip I'I bends to the left in the direction of the arrow so that the look-out switch contacts I8 and I3 separate from each other, and thus open the branch circuit embodying contact elements I3 and I4 of the starter switch 9. The iron circuit of the magnet is represented by the core 22 of winding I I and the armature I2.

Fig. 4, illustrating a modification of Fig. 3, provides a unitary starting and time-delay lock-out switch wherein winding II serves as a common actuating means for the starting element and the time-delay element. Winding II is connected in shunt across the starting element and the time delay element. Bi-metallic strip I! of the thermal time-delay switch II] is replaced by a bimetallic strip 23 which is mounted adjacent to and in heat transfer relationship to winding II. Counter-contact member I4 of the starter switch 9 and counter-contact member I9 of the time delay lock-out switch It are omitted. The armature I2 and the bi-metallic strip 23 are positioned substantially perpendicular to each other. Contact member I8 works with the bi-metallic strip 23 as the counter-contact member of the contact member I3. Contact member I3 is supported by armature I2 and moves therewith upon actuation of the armature. As soon as the spool of the winding II reaches the required temperature, the bi-metallic strip 23 bends to the left in the direction of the arrow, breaking engagement with contact member I3, moving out of reach of armature l2 and thus opens the circuit of the starting and operating switch assembly.

In accordance with our invention, we provide a starting and operating switch which, after a limited number of unsuccessful attempts to start a lamp, cliscontinues the starting operation automatically. Accordingly we provide a starting and operating switch embodying means for discontinuing the starting operation of the switch under abnormal conditions and which upon deenergization is automatically restored to an initial condition for normal operation.

Generally speaking we provide a time-delay lock-out switch and circuit therefor which will eliminate flickering, reduce voltage and current supplied to a defective lamp, and protect the lighting installation from excessive currents. In addition this improved time-delay lock-out switch will operate as effectively on direct current as on alternating current installations. The above described circuits and devices may be applied with equal facility to instant start electric discharge devices and lamps as well as pro-heat devices and lamps. The devices above described are not limited to the circuits therewith described.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a supply circuit, an electric discharge device having at least one filamentary electrode, and means connected in series with said electrode for controlling and starting said device comprising means including a magnetically actuated starting element, a time-delay lock-out means and an actuating means, said time-delay lock out means including a thermal element and said actuating means being connected across said starting element and said thermal element.

2. In combination, a supply circuit, an electric discharge device having at least one filamentary electrode, and means for controlling and starting said device connected in series with said electrode and comprising a parallel circuit including a magnetic switch provided with contacts and an actuating coil therefor and a time-delay switch provided with an actuating means therefor, said actuating coil for said magnetic switch and actuating means for said time-delay switch being connected in series relation and constituting one branch of said parallel circuit, the contacts of the switches being connected in series relation across the actuating means.

3. In combination, a supply circuit, an electric discharge device having at least one filamentary electrode, and means for controlling and starting said device connected in series with said electrode and comprising a parallel circuit including a magnetic starting switch with contacts and an actuating coil therefor and a thermal time-delay switch having thermally actuated contacts and a heating element therefor, said actuating coil for said starting switch and said heating element for said time-delay switch being connected in series relation and constituting one branch of said parallel circuit, the contacts of the switches being connected in series relation across the actuating coil and heating element.

4. In combination, a supply circuit, an electric discharge device having at least one filamentary electrode, and means for controlling and starting said device connected in series with said electrode and comprising a parallel circuit including a magnetic starting switch with contacts and an actuating coil and a thermal time-delay switch having bi-metallic contacts and a heating element comprising a glow discharge tube in close proximity thereto, said actuating coil for said starting switch and said glow discharge tube for starting said time-delay switch being connected in series relation and constituting one branch of said parallel circuit, the contacts of the switches being connected in series relation across the actuating coil and glow discharge tube.

5. In combination, a supply circuit, an electric discharge device having at least one filamentary electrode, and means for controlling and starting said device connected across said device and comprising a parallel circuit including magnetically responsive contact means and thermally responsive time-delay contact means connected in series relation and constituting one branch of said parallel circuit, and actuating means for supplying magnetic energy to said magnetically responsive contact means and thermal energy to said thermally responsive contact means, said actuating means being connected across said magnetically responsive contact means and said thermally responsive contact means.

6. In combination, a supply circuit, an electric discharge device having at least one filamentary electrode, and means for controlling and starting said device connected across said device and comprising a parallel circuit including a magnetic switch provided with contacts and an actuating coil therefor and a thermal time-delay switch mounted in heat-transfer relationship to said coil, said coil comprising one branch of said parallel circuit, the contacts of the switches being connected in series relation across the said coil.

7. In combination, a supply circuit, an electric discharge device having at least one filamentary electrode, and means for controlling and starting said device connected across said device and comprising a parallel circuit including a magnetic switch provided with a movable contact member and an actuating coil therefor and a thermal time-delay switch comprising a bimetallic member mounted in heat-transfer relationship to said coil and carrying a contact normally in position to be engaged by the said movable contact member of the magnetic switch, said bimetallic member being arranged to carry, when heated, its said contact out of the path of movement of the said movable contact member of the magnetic switch, said actuating coil comprising one branch of said parallel circuit, the said contacts of the switches being connected in series relation across the said coil.

8. The combination set forth in claim 3 wherein the said heating element is designed to emit light when the contacts of the time-delay switch are open.

THEODORUS HEHENKAMP. KLAAS 1m JONG.

REFERENCES CITED UNITED STATES PATENTS Name Date Betz Aug. 29, 1944 Number

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