US2286789A - Integral high pressure lamp and starting circuit therefor - Google Patents

Description

June 16, 1942. E, BENCH 2,286,789

INTEGRAL HIGH PRESSURE LAMP AND STARTING CIRCUIT THEREFOR Filed May 1, 1940 INVENTOR 15' C. DF/VC/V ATTO R N EY Patented June 16, 1942 INTEGRAL HIGH PRESSURE LAMP AND STARTING CIRCUIT THEREFOR Edward Charles Dench, South Orange, N. .L, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation 01' Pennsylvania Application May 1, 1940, Serial No. 332,626

2 Claims.

The present invention relates to electric discharge lamps and more particularly to high pressure high intensity mercury arc lamps and starting circuits therefor.

In order, to start lamps of this particular type, a comparatively high starting voltage is required which has necessitated the employment of auxiliary equipment of a cumbersome nature interposed between the commercial source of supply of the customary potential of 115 to 230 volts and the lamp. I

To facilitate starting of these lamps it has been the usual practice to employ a starting electrode disposed adjacent one of the main discharge supporting electrodes and between which a local discharge occurs upon the application of a relatively low potential. This local discharge accordingly ionizes the gaseous medium in the lamp within a few seconds, causing breakdown of the lamp at a much lower voltage than otherwise. Again, however, the necessity for a starting electrode not only increases the manufacturing cost of the lamp, but decreases very little the cost and weight of the auxiliary starting equipment.

It is accordingly an object of the present invention to provide a discharge lamp of the high pressure mercury vapor type wherein the essential portions of the auxiliary starting equipment are enclosed in an envelope with the lamp so as to form an integral unit.

Another object of the present invention is the provision of a discharge lamp of the high pressure mercury vapor type wherein portions of the necessary starting equipment for the lamp are enclosed within the envelope for the lamp and so connected in a starting circuit as to facilitate starting of the lamp without any starting electrode being required.

Another object of the present invention is the provision of a. discharge lamp of the high pressure mercury vapor type which can be readily started at lower voltage than heretofore necessary and without a starting electrode, thus giving a higher power factor operation of the system.

A further object of the present invention is the provision of a discharge lamp of the high pressure mercury vapor type wherein a protective element, is provided in the envelope for the lamp to prevent excessive voltage from destroying other portions of the starting equipment and which also facilitates restarting of the lamp upon a failure of power.

Still further objects of the present invention will become obvious to those skilled in the art by reference to the accompanying drawing wherein:

Fig. 1 is an elevational view partly in section of a high intensity high pressure mercury vapor lamp constructed in accordance with the present invention;

Fig. 2 is a cross-sectional view taken on the line 11-11 of Fig. 1 and looking in the direction indicated by the arrows;

Fig. 3 1s a diagrammatic illustration of the starting circuit for the lamp as shown in Figs. 1 and 2;

Fig. 4 is a diagrammatic illustration which the starting circuit of Fig. 3 may take, and

Fig. 5 is a diagrammatic illustration of a'modification which the lamp and starting circuit may also take.

Referring now to the drawing in detail, the device as shown in Fig. 1 comprises an enclosing envelope 5 of suitable vitreous material, such as glass orthe like, transparent to light; and, if desired, it may bev of quartz or other ultra-violet pervious material. Appropriately secured to the envelope is a base 6 of the usual type to-enable the device to be screwed into a socket.

The envelope 5 is provided with a mount comprising a reentrant stem 1 having the customary press portion 8. A pair of leading-in conductors 9 and ill of suitable metal are sealed to the press and connected to the center contact and shell of the base 6. As will be noted, the leading-in conductors 9 and iii are of rod-like form and widen out immediately above the press portion and extend in parallel relation longitudinally of the enclosing envelope 5.

A pair of bridges l2 and I3 of a suitable insulating material, such as mica or the like, tie the leading-in rods together for the purpose of forming a rigid mount for a discharge lamp ll. This lamp ll asshown is of the high pressure type and comprises an envelope I5 of vitreous material capableof withstanding the high temperature of operation, such as quartz or the like, and provided with a pair of electrodes I6 and i1 between which a discharge occurs when a suitable potential is applied thereto. After evacuation of the envelope I5 through an exhaust tip [8, it is filled with an ionizable medium, such as mercury, together with an inert gas, such as argon, neon, or the like, to facilitate starting with the pressure of the ionizable medium during operation ranging between 5 and '10 atmospheres.

The lamp H as shown has the customary elongated tapering seal at each end to which the leading-in wire for each electrode is sealed. This elongated end passes through openings 20 provided in the bridges l2 and 13, which thus suspends the lamp I 4 between the latter-in firm engagement therewith. Each bridge is in turn provided with a pair of eyelets 22 and 23 secured thereto having annular portions projecting normal to the surface through which the rod-like leading-in conductors 9 and extend; and, after the bridges are in proper position relative to the lamp I4 and the leading-in conductors; the eyelets are secured to the latter in any suitable manner, such for example as by welding.

Upon securing the bridges in place, a flexible lead 24 is welded to the leading-in conductor 9 and to the lower electrode 11, and in a similar,

manner a flexible lead 25 connects the upper electrode 16 to the other leading-in conductor Ill to complete the electrical connection from the base 6 to the opposite electrodes 16 and I1 of the lamp 14. To prevent condensation of the vaporizable material at the coolest portions of the lamp H, which is naturally back of the electrodes, a heat-reflecting shield 26 is positioned at each end of the lamp which may be secured to the insulating interconnecting bridges, such as by tabs or the like.

As will be noted, these shields are of conical form and may be of metal such as nickel, iron,

- or an alloy with the ends of the high pressure.

discharge lamp resting therein with a slight spacing between the greater area of the shield sand the lamp to reduce the thermal conductivity therebetween, which thus conserves the heat to prevent condensation of the ionizable medium rearwardly of the electrodes and at the same time preventing the shields from becoming so hot as to melt the envelope I5. I

In order to initiate a discharge between the electrodes 16 and I] of the high pressure discharge lamp l4, auxiliary apparatus is mounted within the enclosing envelope 5. For example, as shown in Figs. 1 and 2, a gaseous electric relay device 21 is supported by a pair of semi-circular clamps 28, the ends of. which are welded to the respective leading-in and supporting wires 9'and III. This gaseous electric relay device is of the type shown and claimed in U. S. Patent 2,200,443,

which is a heat-responsive element adapted to emit electrons when heated. Upon the application of a potential from the customary source of 115-230 volts, a glow discharge occurs between the electrodes which heats the heat-responsive element. This latter element moves to cause engagement of the electrodes with extinguishment of the discharge. J

As shown in Figs. 1 and 2, the 'heatresponsive element 29 is connected by a conducting bar 30 to the leading-in conductor 9 and the remaining electrodem32 of the gaseous electric relay device is normally connected by means of a thermoexpa'nsive or bimetallic element 33, one end of which is welded or otherwise secured to a support member 34. This support member is in turn welded or otherwise aflixed to the leading-in conductor Ill and is provided with an insulated section such as a glass bead or the like 35 so that the support 34 forms no electrical connection with the leading-in and supporting conductor [0. In order to electrically connect the thermo-expansive element 33 to the leading-in conductor Ill and at the same time limit the current, an impedance, such as a ballast resistor 36, is secured by welding or the like to the leading-in conductor I9 and to the insulated end of the support 34 which thus connects the same to the thermoexpansive element 33.

By reference now to Fig. 3, the electrical circuit thus formed by the auxiliary equipment within the enclosing envelope 5 is shown. The completed lamp is inserted in the usual type of socket and'an inductance 31 is interposed between the source of supply Ll-L2 of the customary domestic potential of '115-230 volts and one of the electrodes 11 of the high pressure discharge lamp 14. shown), a glow discharge occurs in the gaseous electric relay device 21 since the heat responsive electrode 29 is connected by the bar 30 directly to the leading-in conductor 9 and the remaining electrode 32 is connected by the thermo-expansive element 33 and impedance or ballast resistor 36 to the leading-in conductor l0.

Inasmuch as the gaseous electric relay device 21 and impedance 36 are in parallel with the lamp l4, they form a short-circuit for the high pressure discharge lamp 14 so that no current fioWs therethrough, particularly since the resistance thereof is much higher than the circuit including the gaseous electric relay device 21 and impedance 36.

The resulting glow discharge accordingly heats the heat-responsive element 29 causing engagement of the electrodes and extinguishment of the glow discharge, which thus connects the impedance 36 and'inductance 31 across the source of supply Ll--L2. Immediately following extinguishment of the glow discharge in the gaseous electric. relay device 21, the heat responsive element 29 cools sufficiently to cause disengagement of the electrodes 29 and 32. of disengagement of the electrodes the inductance element 31 causes a high voltage surge to be impressed across the electrodes l6 and 11 of the high pressure discharge lamp l4 which accordingly ionizes the medium therein, causing the lamp [4 also functions to short-circuit the'gaseous electric relay device 21 and impedance 36.

Thus the gaseous electric relay device 21 remains inoperative so long as the discharge continues in the highpressure dischargelamp 14. Upon extinguishment of the high pressure discharge lamp 14, however, the gaseous electric relay device 21 will again perform its cycle of operation to initiate a discharge in the high pressure discharge lamp I4. The circuit thus far described is exactly as shown in Fig. 5. However. in order to prevent the heat generated by the high pressure discharge lamp H from inadvertently heating the heat-responsive element 29 of the gaseous electric relay device 21,the thermoexpansive element 33 is provided, as diagrammatically shown in Fig. '3.

In this particular modification and as shownin Figs. 1 and 2, the thermo-expansive element Thus upon closure of a suitable switch (not At the instant I cordingly heats the thermo-expansive element 33 causing it to ilex in the manner shown in dotted lines in Figs. 2 and 3, which thus disconnects the gaseous electric relay device 21 from the impedance I6 and consequently from the leadingin conductor l0. Consequently, even should the high temperature of the high pressure discharge lamp ll inadvertently heat the heat-responsive element 29 of the gaseous electric relay device 21, causing it to engage the remaining electrode 32, the high pressure discharge lamp i4 is not thereby short-circuited so as to extinguish the discharge, as might otherwise be the case in the arrangement shown in Fig. 5.

Naturally, the provision of the thermo-expansive element 33 is not always necessary inasmuch as the gaseous electric relay device may be disposed in the coolest portion of the enclosin envelope 5. such as shown in Fig. i, so that it is not heated sufliciently by the high pressure discharge lamp ll as to cause inadvertent operation of the heat-responsive element or the gaseous electric relay device 21.

In the circuit arrangement shown in Fig. 4 a modification is shown which is identical to that previously described with respect to Figs. 3 and 5, with the exception that an auto-transformer 38 is shown in lieu of the inductance 31 01' Figs. 3 and 5.

It thus becomes obvious to those skilled in the art that a high pressure discharge lamp is herein provided wherein the essential portions of the auxiliary starting equipment areenclosed in a single envelope with the lamp so as to form an integral unit. Moreover, the auxiliary equipment is so mounted and connected to the lamp that a discharge is readily initiated without the necessity of an auxiliary starting electrode as heretofore required. Due to the construction herein disclosed the integral unit may be readily inserted in the customary sockets so as to be energized from the usual source or commercial potential.

Although several embodiments of the present invention have been shown and described, it is to be understood that still further modifications thereof may be made without departing from the 'spirit and scope oi the appended claims.

I claim:

1. A high pressure gaseous discharge lamp electrical energy to the electrodes of said lamp, an impedance supported within said enclosing envelope, a gaseous electric relaydevice supported within said enclosing envelope-provided with an ionizable medium therein and a pair of electrodes one of which is a heat-responsive element and between which a glow discharge occurs upon the application of a potential therebetween, and operable upon heating of said heat-responsive element by the ensuing glow discharge to cause extinguishment of the latter and to connect said impedance across said leading-in conductors to short-circuit said lamp, and said gaseous electric from said lamp causing undesired operation of of said lamp, an impedance adapted to be con nected to said source, and a gaseous electric'relay device provided with an ionizable medium therein and a pair of electrodes one of which is a heatresponsive element, and between which a glow discharge occurs upon the application of a potention from said source and operable upon heating of said heat-responsive element by the ensuing discharge to extinguish the latter and initially connect said impedance to said source and to short-circuit said lamp, and said gaseous electric relay device being thereafter operable upon cooling of said heat-responsive element to disconnect said impedance from said source and to remove the short-circuit of said lamp as well as simultaneously cause a high voltage surge from said inductance to initiate a discharge in said lamp, and a thermo-e pansive element normally connecting one electr e of said gaseous electric relay device to said impedance and operable upon heating thereof to prevent short-circulting of said lamp during its operation by the inadvertent operation oi said gaseous electric relay device.v

EDWARD CHARLES DENCH.

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