US2656488A - Electric discharge device starter - Google Patents

Description

20, 1953 s. M. GRAY ET AL ,6 6, 88

' ELECTRIC DISCHARGE DEVICE STARTER Filed 001;. 29, 1949 4 INVENTORS. SAMUEL ATTORNEY Patented Oct. 20, 1953 ELECTRIC DISCHARGE DEVICE STARTER.

, Samuel M. Gray,.Marblehead, and Raymond C. Svenson, Beverly, Mass., assignors to Sylvania Electric Products Inc., Salem, Mass., at corporation of Massachusetts Application October 29, 1949, Serial No. 124,432

2 Claims. 1

This invention relates to the starting of electric gaseous discharge devices, and to methods and apparatus therefor.

Such devices generally require a greater voltage at starting than is thereafter required to maintain the discharge.

An object of our invention is to facilitate the starting of such devices, and a further object is to reduce the starting voltage required.

We have found that the starting voltage neces sary may be greatly reduced by applying it across the lamp in opposite polarity to that of the operating voltage. We have also found that the starting, voltage may be applied by charging a condenser and then discharging it across the lamp, and that when so applied the starting voltage necessary becomes less, approaching a limiting value as the amount of energy in the condenser is increased.

Accordingly, a feature of our invention is the application to the lamp of a transient starting voltage opposite in polarity to the main operating voltage. Another feature, is the application of the starting voltage by charging a condenser and discharging it across the lamp.

Other features, objects and advantages of the invention will be apparent from the following description, taken in connection with the accompanying drawing, in which:

Figure 1 shows one modification of a starting circuit according to the invention; and

Figure 2 shows the relation of starting voltage to condenser energy required with and without reversed polarity.

In Figure 1 the generator or other source I of direct current is connected to the electrodes 2, 3 at the ends of lamp l3 through the ballast resistor 4, and the contacts 5, 6 for the double-pole double-throw switch levers 'l, 8, are likewise connected to the electrodes 2, 3. The other contacts 9, In to which switch levers 1, 8 may be'thrown for connection, are connected to a second source ll of direct current. The condenser I2 is connected between the switch levers 'l and 8.

According to the invention, the switch levers 'l and 8 may be thrown into connection, respectively, with contacts 9 and [0, thus connecting the condenser [2 to the direct current source ll. When the condenser is charged, the switch levers l and 8 may be thrown into connection, respectlvely, with contacts 5 and 6, thus discharging the condenser into the lamp l3 and generator I. If the voltage to which the condenser was charged is sufficient, the lamp will start. Once the energy in the condenser is dissipated in starting the discharge, or becomes equal to that corresponding to its capacity and the lamp voltage, the condenser may be left in circuit or removed therefrom by opening the switch 1, 8. For safety in handling the condenser, it may be discharged through a resistance when not in use.

If the polarity of the charged condenser is the same as that of direct current source I, that is if contacts 5 and 9 are both positive or both negative, switch lever I then also being of the same polarity as said contacts, the starting voltage will vary with the condenser energy in joules as shown in curve A of Figure 2.

The voltage required for starting will be reduced if the condenser I2 is switched into connection with contacts 5 and 6 with its polarity opposite to that of the lamp l3, or direct current source I. In this case, contacts 9 and switch lever I will be opposite in polarity to contact 5, and contact l0 and switch lever B will be opposite in polarity to contact 6.

The curve of starting voltage, that is the voltage required across the condenser l2 to start the tube, against condenser energy is shown as curve B in Figure 2.

Comparison of this curve with curve A shows that the required starting voltage may be reduced tremendously by applying it in opposite polarity to that of the lamp operating voltage.

For example at 0.1 joule condenser energy the starting voltage was reduced from 3300 volts to volts by reversing the condenser polarity.

The curves are for a lamp of one inch diameter, '72 inches long, with a filling of argon at a pressure of about 3.5 millimeters of mercury, and mercury vapor at a pressure of a few microns. The lamps had cold cathodes, that is cathodes of cylinders coated with alkaline earth oxides, but not pre-heated before starting the discharge. The lamp operating current was about milliamperes, and the line voltage of source I was,

1. Apparatus for starting and operatinga gase-.-

ous discharge lamp, said apparatus comprising a source of voltage of given polarity and sufiicient to maintain said lamp in operation but insufli- ,cient of itself to start said lamp, said source of voltage being connected'in series with said lamp,

and a condenser connected to discharge across said lamp a transient voltage of opposite polarity to that of said source, for starting said lamp.

2. Apparatus for starting and operating a gaseous discharge lamp, said apparatus comprising: a source of voltage of given polarity and a ballast impedance in series with said lamp; a condenser; a source of voltage for charging said condenser; and a switch for disconnecting said condenser from sail sofiriie or pharging' voltage and .connecting flie'condensei' across -said lamp 'in opposite polarity to that of said first-mentioned source.

sAMUELM. ems. RAYMGND cilsvmson.

References Cited in the file of this patent UNITED STATES PATENTS muses Name Date Perrin May 1, 1945 Camras Dec. 3, 1946 sghellenp 1 Bee. 3, 1946 Maxwellfla Dec. 2, 1947 Schreiber July 19, 1949 Rochester Aug. 1, 1950 FOREHGN PATENTS Country Date GiZfBritain Oct. 15, 1948

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