US2504594A - Device comprising a gas-and/or vapor-filled discharge tube - Google Patents

Description

April 8, 1950 P. SCHOUWSTRA ETAL DEVICE COMPRISING A GAS-AND/OR VAPOR-FILLED DISCHARGE TUBE Filed April 27, 1946 INVENTORS;

PIETER SCHQUWSTRA, PETRUS JOHANNES MARIA MUTSAERS,

BY UJMUJ 0 KW THEIR ATTORNEY i atented Apr. 18, 1956 UN STATES oFFiics Section '1, Public Law 690, August 8, 1946 Patent expires November 16, 1962 (01. sis-51) '2 claims. 1

This invention concernsa device comprising a gasand/or vapor-filled discharge tube, an iriductance mainly for ignition purposes and an automatic, for instance thermal, circuit breaking switch which is connected in parallel with the tube. On opening the switch the inductance in the device referred to delivers a voltage impulse initiating the ignition er the tube. Such an inductance is mainly required when the stabilisation impedance is not possessed of any appreciable inductance such as is the case with condensers and ohmic resistances, and for instance incandescent lamps. The inductance may also be required when the stabilisation impedance of the tube possesses an inductance, but which is zero or low before ignition. This occurs in circuit arrangements in which the value of the inductance is artificially reduced by counter windings, magnetic or other expedients before ignition, in order that the electrodes of the tube may be heated more rapidly.

The location or mountingof the additional inductance for igniting the discharge tube, which is usually connected in series with the tube, but may also be connected in parallel with the tube in many cases, entails difficulties.

The present invention purports to avoid this mounting difficulty. The novelty is based on the realisation that the value of the inductance may be comparatively low, in many cases of the order of magnitude of mI-I.

According to our invention the circuit breaking switch is equipped with a cylindrical envelope on which are wound the turns of the inductance. Between the switch and the winding of the inductance coil 2. tube may be provided which is slotted in an axial direction and made from a material which is a better magnetic conductor than air. This measure permits of reducing the number of turns of the inductance coil. The said slotted tube may often constitute the envelope of the switch.

In the devices referred to in the preamble use is often made of condensers that are connected to the electrodes of the discharge tube. The impedance of such condensers, which are usually employed in alternating current installations and which mainly serve for the removal of radio interferences, is a multiple of the tube impedance. In an advantageous form of construction of our invention the plates of this condenser surround the axis of the switch envelope helicoidally. In this case the plates are provided on the inductance coil or below the latter.

The units including the interruptor, inductance device are so housed as to be invisible. This method is particularly suitable for elongated dis charge tubes having two holders, for instance, for luminescent mercury vapor tubes having a low vapor pressure.

As an alternative the unit may be incorporated in a cap of the discharge tube. This mounting method is particularly suitable for discharge tubes having only one cap, for instance u-shaped sodium vapor discharge tubes.

The novelty will be more fully explained by reference to the accompanying drawing, given by way of example.

Figure 1 of this drawing represents a wiring diagram of a device constituting the object of the present novelty. Between the terminals l and 2 of the device are connected in series with each other an incandescent lamp 3, the heater winding 4 of a thermal switch, an inductance coil 5, an electrode 6 for a discharge tube 1, a bimetallic element 8 cooperating with the heater winding 4, a contact member 9 provided thereon, a counter contact member Ill cooperating therewith and the second electrode I l of the discharge tube 1. When connecting the terminals I and 2 of the device to a suitable supply e. g. A. C. mains of 220 volts-50 cycles/sec. the incandescent lamp 3 is made to glow and the filamentary electrodes 5 and l l of the discharge tube equipped with electron emitting material, are heated. At the same time heat is supplied from the heater winding 4 to the bimetallic element 8. This bimetallic element is so shaped as to warp as a result thereof in such manner that the contact members 9 and ill move away from one another. Owing to this interruption between the members 9 and It the current through the inductance coil 5 is also interrupted, whereupon its magnetic field breaks down and yields a voltage impulse capable of initiating the discharge between the electrodes 6 and II of the discharge tube 1 now having the emission temperature.

In Fig. 2 the discharge tube '1 of this device is represented separately. This discharge tube may, for instance, be a sodium vapor lamp designed for the emission of light.

The thermal switch shown in Fig. 1, which consists of the heating element 4, the bimetallic element 8 furnished with the contact member 9, and the counter contact member ill is incorporated in a tubular or cylindrical exhausted envelope l2. For ease of reading solely the envelope l2 of the switch is represented in Fi 2. This envelope I2 carries a frictionally engaging cylinder 13 which is slotted in an axial direction and consists of, for example, a strong magnetically permeable metal sheet having a thickness of 0.4 mm. This cylinder carries the inductance coil which consists of about 150 turns of strong copper wire having a thickness of 0.5 mm. The said slit of the tube l3 has a width of about 1 mm. This unit, which includes the switch l2 and the inductance coil 5, is supported by the connecting wires to the electrode of the discharge tube and to the terminals of the base assembly or Goliath cap 14 surrounding them. Between the unit and the cap may be provided a filling mass, if required. An anti-interference condenser of about 10.000/L/Lf, which may be available and is indicated in dotted lines at 15 in Fig. 1, may be provided as a wound condenser on the cylindrical surface of the inductance coil 5.

What we claim is:

1. In combination, an arc discharge device of the type employing an ionizable medium and comprising a plurality of electrodes at least one of which is of the filamentary type, an enclosing envelope surrounding said are discharge device, a generally cylindrical base assembly secured to said enclosing envelope, a starting switch enclosed within a cylindrical envelope and mounted within said base assembly axially thereof and having its contacts electrically connected in parallel with said arc discharge device, a metallic cylinder surrounding said cylindrical envelope,

and a ballasting inductance in series with said are discharge device and wound around said metallic cylinder.

2. In combination, an arc discharge device ofthe type employing an ionizable medium and comprising a plurality of electrodes at least one of which is of the filamentary type, an enclosing envelope surrounding said are discharge device, a generally cylindrical base assembly secured to said enclosing envelope, a starting switch enclosed within a cylindrical envelope and mounted within said base assembly axially thereof and having its contacts electrically connected in parallel with said arc discharge device, a magnetically permeable cylinder surrounding and frictionally engaging said cylindrical envelope, a ballasting inductance in series with said are discharge device and wound around said metallic cylinder, and a condenser comprising a pair of cylindrical plates surrounding said cylindrical envelope.

PIETER SCHOUWSTRA.

PETRUS J OHANNES MARIA MUTSAERS.

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

UNITED STATES PATENTS Number Name Date 2,297,885 Gustin et a1. Oct. 6, 1942 2,313,745 Hays et al Mar. 16, 1943 FOREIGN PATENTS Number Country Date 310,895 Great Britain Oct. 2, 1930

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