US2313575A - Electric discharge apparatus - Google Patents

Description

March 9, 1943. L. R. PETIERS 2,313,575

ELECTRIC DI SCHARGE APPARATUS Filed Jan. 27, 1941 L Inventor:

Leo R. Peter's,

His Attorney.

Patented Mar. 9, 1943 UNITED, PATENT OFFICE Leo R. Peters, East Cleveland, Ohio, assignor t General ElectricGompany, a' corporationof New York Application January 27, Iii ll, Serial No. 376,087, 7 Claims. (01. 176 -124) My invention relates to electric, discharge apparatus of the type comprising a, gaseous electric discharge device provided with thermionic; electrodes and arranged to be operated from a,

sourceof alternating currentv supply. It'relates, particularly to apparatus such as disclq fid. by Figfl of the Wels Patent 1,951,112.

Apparatus such as disclosed by that figure has been found to have the objection that the time required for the heat responsive switch to reclose after an interruption in the current supply is indeterminate and in eneral too long for. present purposes. It is the object of my invention to provide improved. apparatus of that type which will avoid the above noted objection and will maintain the switch at temperatures having a limited range of variation.

My invention will be better understood from the following description taken in connection with the accompanying. drawing, and its scope will be pointed out, in the appended claims.

Referring tothe drawing, Fig. 1 is a circuit diagram illustrating one embodiment of my invention, Fig. 2 is a top view of a commercial form of the switching mechanism andFig. 3 is'a side view thereof.

In the drawing, i represents a gaseous electric discharge device such as a discharge lamp having the thermionic electrodes 2 and 3 therein illustrated as filaments which are'arranged to be initially heated to an electron emitting temperature before the startingvoltage is applied to the device. The lamp is shown connected to be operated from a suitable source of alternating current supply 4 which may be a Gil-cycle, 115'- volt lighting circuit. The connections between the lamp and the source 4 are represented by 5 andfi, each of which connects with an electrode at one end thereof. shown including the main switch I and'the bal: last 8 for. the lamp which is represented as 'a reactor,

Forcompleting a circuit by which heating current may flow through the'lamp electrodes to effect the initial heating thereof, I'have 'pro5 vided. the thermal or heat responsive switch). The movable contact of theswitch is actuated by the bimetallic strip H, one end of which is fixed and is connected with the otherend of the electrode 2. The cooperatingfixed front contact I2'is shown supported on the bimetallic strip l3 which is connected with the other end'ofthe electrode 3 and is normally engaged by the con-. tactcarried by the strip II when the latteris not heated. The strip H is heated by, the resistance heater M which is arranged in thermal relation therewith and which is connected in series in the connection 5. The switch II) also is provided with the back contact l5 which is normally spaced only a small distance from the movable These connections are.

contact when the same is in engagement with the contact l2 and which is shown supported oii the. bimetallic strip it. The switch parts are shown enclosed in the evacuated envelope 9, which, if desired, may contain a small amount of; an, inert gas. The contact I5 is connected through the resistor H with that end of the heater l4 which is remote from the device I. Very satisfactory operation with this apparatus has been obtained when the resistance of the resistor 57 has been approximately equal to that of the heater i4. With this contruction the heating of the bimetallic strip II by its heater will cause it to bend away from the contact l2 into engagement with the contact l5, whereupon heater and the resistor in parallel. The sever-a1 bimetallic strips are arranged to bend in the same direction with an increase in the temperature of the ambient whereby compensation is made for such temperature changes.

When the apparatus is initially connected with the source of supply 4 by th closing of the switch 1; a discharge does not immediately start in the device as the voltage applied thereto is insufiicient. Current flows in series, however, through the switch, the reactor, the heater, the electrode 2, the thermal switch including parts H, l2 and I3, and the electrode 3, the electrodes being quicklybrought to an electron emitting temperature. since the current at this time is approximately twiee that which flows through the device during its, normal operation. The heating of the bi- 'metallic strip I l causes it to warp away from the contact l2, thereby opening the circuit between the electrodes and causing a starting voltage'to be; applied tothe lamp in the well understood manner. The discharge having started in the device, heat is still supplied by the heater to the bimetallic strip II, and although of less degree;

than before, still it is sufiicient to hold the strip away from the contact l2. Were there no back contact IS, the strip would finally come to rest at, a position which is somewhat indefinite, de pending upon various factors. By employingthe back contact l5 spaced only a short distance away and connected through the resistor ll with the heater M, the engagement of the contact This reduction in the,-

repeated. Thus it will be seen that the heating of the bimetallic strip l l is never materially more than that required to move it through the small space separating it from the back contact. This has the important advantage that in the event of an interruption of the source of current supply the time required for the reclosing of the switch can be determined with considerable exactness and also is reduced to a practicable minimum. Were the back contact L to be connected directly with the end of the heater without the resistor, the resistance change in the connection between the device and the source would be that due to the full effect of the heater as the switch alternately connects and disconnects with its back contact. However, by using a resistor such as shown at I! in the connection with the back contact, the change in resistance with the operation of the switch is reduced and where the resistance of the resistor is approximately equal to that of the heater, the change in resistance is only about half of what it would be without the use of the resistor.

A further advantage is that, whereas a certain amount of flicker often occurred at that end of the lamp having the electrode 2 due to the tendency of the discharge to jump from one end of that electrode to the other at each make and break of the switch with the back contact, the use of the resistor ll avoids such flicker.

A commercial form of the above described switch in which the bimetallic supporting strips 13 and 46 are not used is represented in Figs. 2 and 3 where the parts are shown mounted in an evacuated sealed receptacle H! which also contains the resistor 17. If desired, the receptacle may contain a small amount of gas, for example, 1 to 2 cm. of nitrogen, in order to provide for a greater rate of heat transmission to the bimetallic strip from the heater and a greater rate of heat loss from the strip. Figs. 2 and 3 show the envelope comprising the metal base plate l9 and the metal cap 20 sealed thereto. To the several terminal studs 21 which are sealed in the base plate are secured the bimetallic strip II, the two switch contacts 12 and i5, which in this case are fixed, the heater and the resistor, as will clearly appear. The bimetallic strip ii is shown in the form of a spiral of one turn surrounding the heater which is a spiral or coil of resistance wire.

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

1. In electric discharge apparatus comprisingan electric discharge device connected to be operated from a source of alternating current supply and provided with thermionic electrodes, a resistance heater in said connection, a heat responsive time delay switch in thermal relation therewith and connected between said electrodes to control the flow of heating current therethrough, and means comprising a member arranged to cooperate with said switch and operative during the operation of said device to reduce the heating of said switch in response to a determined opening movement thereof.

2. In electric discharge apparatus comprising an electric discharge device connected to be operated from a source of alternating current supply and provided with thermionic electrodes, a resistance heater in said connection, a heat responsive time delay switch in thermal relation therewith and connected between said electrodes to control the flow of heating current therethrough, and means comprising a contact member in the path of movement of said switch operative after the device has started and responsive to a predetermined opening movement of said switch for reducing the heat supplied by said heater.

3. In electric discharge apparatus comprising an electric discharge device connected to be operated from a source of alternating current supply and provided with thermionic electrodes, a resistance heater in said connection, a heat responsive time delay switch in thermal relation therewith and connected between said electrodes to control the flow of heating current therethrough, and means comprising an additional contact for said switch operative after the device has started and responsive to a predetermined small opening movement of said switch for reducing the heat supplied to the switch.

4. In electric discharge apparatus comprising an electric discharge device connected to be operated from a source of alternating current sup- .ply and provided with thermionic electrodes, a resistance heater in said connection, a switch connected between said electrodes to control the flow of heating current therethrough comprising a thermally responsive element adjacent to said heater and a circuit controlled by the movement of said element for supplying discharge current to the device in shunt with said heater.

5. In electric discharge apparatus comprising an electric discharge device connected to be operated from a source of alternating current supply and provided with thermionic electrodes, a resistance heater in said connection, a bimetallic switch in thermal relation with said heater and connected between said electrodes to control the flow of heating current therethrough, a circuit for supplying discharge current to said device in shunt with said heater, and means actuated by the opening movement of said switch for closing said circuit.

6. In electric discharge apparatus comprising an electric discharge device connected to be operated from a source of alternatin current supply and provided with thermionic electrodes, a resistance heater in said connection, a switch comprising a front contact and a cooperating bimetallic member in thermal relation with said heater connected between said electrodes to control the flow of heating current therethrough, said switch having a back contact and a resistance connected between said back contact and that end of said heater the more remote from said device.

'7. An electric discharge lamp having thermi onic electrodes, a lead arranged to connect one end of each of said electrodes with a source of alternating current supply, a resistance heater in one of said leads, a switch comprising a bimetallic strip in thermal relation with said heater and connected with the other end of one of said electrodes, said switch having a front contact connected with the other end of the other of said electrodes and having a rear contact and a resistor whose resistance is approximately equal to that of said heater connected between said rear contact and said heater at the end thereof remote from said lamp,

LEO R. PETERS.

, CERTIFICATE OF CORRECTION. Patent, No. 2,513,575. March 9, 1915.

LEO R. PETERS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 65, for "determined" read --predetermined; and that the said Letters Patent shofild be read with this correction therein that the same may conform to the record of the case in the Pateht Office.

Signed and sealed this 20th day of April, A. D. 1915.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

CERTIFICATE OF QORRECTION. Patent No. 2,515,575. March 9, 1&5.

LEO R. PETERS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 65, for "determined' read predetermined-; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 20th day of April, A. D. 1915.

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

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