US2462306A

US2462306A - Control switch for discharge lamps

Info

Publication number: US2462306A
Application number: US616907A
Authority: US
Inventors: Leonard W Cook
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1945-09-17
Filing date: 1945-09-17
Publication date: 1949-02-22
Anticipated expiration: 1966-02-22

Description

Feb. 22, 1949. w, COOK 2,462,306

CONTROL SWITCH FOR DISCHARGE LAMPS Filed Sept. 17, 1945 Inventor- Leon arci W.C 00 k,

H i s Attorney;

Patented Feb. 22, 1949 CGN'ERGL SWITCH FOR DISCHARGE LAMPS Leonard W. Cook, Stratford, Conn., assignor to General Electric Company, a corporation of New York Application September 17, 1945, Serial No. 616,907

6 Claims.

My invention relates to a control switch for starting and operating gaseous electric discharge lamps and more particularly to a starting switch for fluorescent lamps used in commercial and residence lighting systems.

In such lighting systems the discharge lamps are connected in series with a ballast across a source of electric power together with a starting switch in parallel with the lamp but in series with the lamp electrodes. When the control switch opens the circuit between the electrodes, the ballast applies a high voltage kick to start the lamp. Such control switches are known to the trade as starters.

Such starters as presently designed. provide for an appreciable preheating time for the filamentary electrodes of the lamp to bring them up to an emissive temperature before applying the high voltage from the ballast to start the lamp. However, with certain types of fluorescent lamps now on the market, appreciable preheating of the electrodes is unnecessary. The lamp may be started without any substantial preheat of the electrodes or with cold cathodes.

Although present day lamps are designed for instant starting with little, if any, preheating of the electrodes, or for cold cathode starting, starters of the type now commercially available will not start a lamp fast enough to avoid a noticeable delay in lighting after the power supply switch is closed and, in any event, do not start a lamp with the speed at which the lamp is capable of being started.

One such type of starter now on the market employs a glow switch having two electrodes one of which is bimetallic. When the lamp operating circuit is closed, a glow discharge takes place between the electrodes to heat the bimetallic electrode to close the circuit through the glow switch. This extinguishes the glow discharge and causes a preheat current to flow through the lamp filaments. When the bimetallic member cools down, the circuit through the glow switch is opened causing the ballast to apply a high voltage across the filaments to start the lamp. Although this starter operates satisfactorily when it is desired to preheat the lamp electrodes, it fails to provide an instant starting action for lamps of the type now commercially available in which no appreciable preheating of the electrodes is required and which may, in fact, be started with cold cathodes.

When thermal-type starting switches are employed, an unavoidable time delay is encounteredin heating and cooling the relatively heavy bimetallic strips. When glow switches alone are emplcyed, an appreciable delay occurs after extinguishment of the glow discharge waiting for the bimetallic element to cool down.

A magnetic vibrator type of starter has been used in certain instances and which opens the circuit across the lamp filaments almost instantly after closure of the .power switch. However, in such circuits, the actuating element of the magnetic coil of the switch is continuously in the lamp circuit during operation of the lamp to maintain the contacts in open position with consequent loss of power. This objection has been overcome to some extent by employing a voltage responsive device such as a glow lamp in series with the magnet coil, the two being in parallel with magnetically operated contacts. The glow lamp cuts ofi the magnetic switch from the power supply during operation of the lamp. Such an arrangement is disclosed in Patent 2,212,427 issued on August 20, 1940 to Leo R. Peters and assigned to the same assignee as the instant application.

While for certain applications, the circuit of the Peters patent operates satisfactorily, it has been found that part of the voltage obtained across the vibrator contacts is absorbed in the glow lamp and coil and hence is not available across the lamp electrodes.

The disadvantages of the aforementioned starters are overcome by my new and improved starter. It employs a glow discharge device and magnetic switch in series between the lamp electrodes. It operates extremely fast to supply high voltage from the ballast to give a practically instantaneous start of the lamp after closure of the power supply switch. After the lamp starts, the starter is blocked out of the circuit so that it consumes no current. In'certain applications, the starter may be provided with a lock-out mechanism which will cut the starter out of the lamp operating circuit if the lamp fails to start after a predetermined number of attempts.

Therefore, one object of my invention is to provide a new andimproved starter for electric discharge lamps, which will start the lamps almost instantaneously.

Another object of my invention is to provide an improved starter which includes means for starting the lamp instantaneously, in combination with a mechanism for locking the starter out of the lamp operating circuit in the event that the lamp fails to light after several starting attempts.

In the accompanying drawing, Fig. 1 is a schematic view showing a starter constructed in accordance with my invention and connected into a lamp operating circuit; and Fig. 2 is a view 3 of the starter similar to Fig. 1 but with the addition of a lock-out mechanism.

Referring to Fig. 1 of the drawing, I have shown my starter in schematic form connected into an operating circuit for a discharge lamp. The discharge lamp may comprise a fluorescent lamp I of a type now on the market and which is provided at each end with electrodes 2 formed as filamentary cathodes. On one side the electrodes are connected across power lines 3 and 4 which, for example, may comprise a 115 volt A.-C. power supply such as is now commercially available for residence use. Connected into the power line 3 is a ballast 5 for supplyingv high voltage to start the lamp. The ballast is illustrated as comprising an inductance or choke coil but it should be manifest that the ballast may equally well comprise a transformer or resistance depending upon the voltage requirements of the lamp and the voltage available at the power supply. A switch 6 controls the application of power to the lamp operating circuit and is used to turn the lamp on and off.

While the discharge lamp I is illustrated as being provided with filamentary electrodes, which may be used in a circuit providing preheat, these electrodes are actually of the type which require practically no preheating before the application of the high voltage from the ballast to initiate a discharge in the lamp. In other words, the lamp is so constructed that it may be started simply by applying a high voltage across the electrodes without preheating them.

On the other side the electrodes are electrically connected in series with a control unit or starter constructed in accordance with my invention. The. starter comprises a glow discharge device 7 electrically connected in series with a magnetically operated switch 8. A condenser 9 is connected electrically in parallel across these elements. The capacity of the condenser affects the peak output voltage obtained by the starter and also servesto reduce radio interference.

The glow discharge device 1 comprises a high current glow lamp having tungsten electrodes of relatively large area so that the lamp is capable of carrying relatively heavy currents ordinarily sufficient to preheat the lamp electrodes although in the instant circuit no appreciable preheating of the filamentary lamp electrodes takes place. This current may be of the order of 300 to 600 milliamperes. The tungsten electrodes are sealed within a glass envelope in an atmosphere of a suitable inert gas such as neon, or the like. As shown by Fig. 1, one electrode of the glow lamp is connected by a lead wire In to the left-hand lamp electrode 2 while the other electrode is connected by conductor H to the magnetic switch 8.

The switch or relay 8 comprises spaced contact members l2 such as silver contact buttons which are normally closed by means of a contact bar l3 carried by an iron armature I 4. The armature extends through a'solenoid coil l5. One end of the coil is electrically connected in series with the fixed contacts while the other end is connected by a lead wire 16 to the other lamp electrode 2. The 'cont'actbar is normally biased into engagement with the fixed contacts by a spring ll. The arrangement is such that the circuit through the switch is normally closed. As soon as the coil is energized the switch operates to open the'circuit through the starter. The contact bar. l3 and associated armature 'M are made of relatively light construction 'so'that'the 4 switch has a very fast action upon being energized.

My starter operates as follows:

When switch 6 is closed to supply power to the lamp operating circuit, open circuit voltage is applied across the electrodes of the glow lamp i to initiate a .glow discharge. Immediately, a relatively heavy current flows through the glow lamp to energize the switch 8. A circuit is then completed from power supply line 3 through ballast 5, the left-hand lamp electrode 2, glow lamp T, conductor li', switch contacts l2 and I3, coil 15, the right-hand lamp electrode 2 to the other power line 4. As soon as voltage is applied to the magnetic switch 8, the normally closed contacts of the switch are opened by the magnetic flux of the coil i5.

When the switch contacts open, the circuit through the starter is interrupted so that a very high voltage kick is obtained .from the inductive ballast 5 and which is applied across the lamp electrodes. Frequently. one such surge of voltage is sufiicient to start the lamp but ordinarily the sequence of operation of the magnetic switch must be repeated two or three times before the lamp discharge is established. It'will be apparent that as soon as the switch contacts open, the coil i5 will be deenergized permitting spring H to reclose the contacts. In other words, as long as power is applied to the switch through the glow lamp the magnetic switch will vibrate to provide a series of impulses or voltage kicks to the lamp l.

The series of voltage impulses are repeated i very rapidly so that the ionization produced in the lamp by the first voltage impulse will be built up and reinforced by the second impulse and also the third one and so on until the lamp lights. Stated technically, the starter is so designed that the periods of interruption of current, i. e., the periods during which the contacts of the magnetic switch are open to produce high voltage impulses to the lamp, are shorter than the deionization time of the arc discharge in the lamp.

As already mentioned, the glow lamp passes a relatively heavy current on the order of 300 to 600 milliamperes. This provides sufficient power for 'fast and reliable operation of the magnetic switch. In addition, since a relatively heavy current is passing through the inductive ballast a magnetic flux of considerable strength is built up so that when the current is interrupted by operation of the starter an extremely high voltage is developed by the ballast.

Condenser 9 functions to store part of the inductive energy obtained from the ballast. The capacity of the. condenser may be varied somewhat to vary the peak output volts applied across the lamp filaments. When used with a 40 watt lamp and -115 volt A.-C. supply the condenser may be approximately 0.2 mid. 'Its capacity is such that it serves to release some of the energy stored therein during the intervals between succeeding high voltage impulses. In this way, the condenser aids the starting-action. In addition, the condenser acts to reduce radio noise by absorbing the harmonic frequencies developed in the lamp arc discharge.

As soon as the lamp lights, the voltage across the glow lamp 1 is reduced to that existing across the arc discharge in the lamp I. This is insufficient to maintain the discharge in the glow lamp so that it no longer passes current to energize switch 8. Thus the starter is immediately cut out of the circuit. In this way, the glow lamp prevents any consumption of power in the starter mechanism while thelamp l is lighted.

In the event that the lamp fails to light within the first few vibrations of the magnetic switch, such as is ordinarily the case, the switch will continue to operate in the manner indicated. However, it is not desirable to permit the starter to operate for any appreciable length of time. If the lamp is defective and fails to start after several attempts have been made, I provide a mechanism for locking the starter out of the lamp operating circuit.

Fig. 2 illustrates one form of lock-out mechanism which is suitable for use in my starter. It comprises two bimetallic blades [8 and I9 connected in series in the circuit between the magnetic switch 8 and conductor it. Each bimetallic blade carries a contact buttbn, the buttons being normally in engagement with each other so that the circuit through the bimetallic blades is normally closed. A heating resistor 20 is connected between the conductors l9 and IS in parallel with the glow lamp 7 and magnetic switch 8. If the lamp fails to start within a short time interval, the full line voltage existing across the lamp l and between conductors it and I6 causes the resistor to heat up to an extent sufficient to'cause bimetallic blade E9 to move U away from the blade Hi. This opens the circuit through the starter. It remains in open-circuited condition as long as power is applied to the system and as long as the lamp fails to light. When power is turned 01 or when a lamp is replaced thereby interrupting the circuit, the resistor cools ofi permitting the bimetallic members to reclose to reset the starter. Thus the starter is reset automatically. When the lamp lights, the voltage applied to resistor 2!] is reduced so that the heat developed in the resistor is insufiicient to move the bimetal 29. In such instances the starter is blocked out of the circuit by the glow lamp 1.

The lock-out mechanism has the advantage that, if the lamp is defective, the starter will not make attempts continuously to start the lamp. Such repeated starting attempts frequently cause the lamp to flash repeatedly particularly when the lamp is at the end of its rated life. Such flashing is objectionable and is overcome by the lock-out mechanism. Since the starter is locked-out of the circuit after a number of attempts to start the lamp, the starter itself is protected against damage and its life greatly increased. The resistor '26 consumes only a small amount of power in maintaining the starter locked out. The two bimetallic members l8 and I9 are arranged to deflect in the same direction when subjected to temperature changes. In this way the lock-out mechanism is compensated for changes in ambient temperature.

The starter is adapted for use in lamp operating circuits which are designed to give either cold cathode starting or preheat starting of the lamp. In other words, the starter may be used to give instant starting in existing lamp operating circuits equipped with preheat starters without rearranging the circuit connections and without replacing the ballast or lamp sockets. It is only necessary to interchange the starters. As already mentioned, the starter operates instantaneously to apply a very high voltage across the lamp electrodes without preheating and in this way starts the lamp with the cathodes cold in a circuit originally designed for preheating. The starter mechanism can be used interchangeably with preheat starters in existing installations employing relatively low voltage ballasts, when an instant start lamp is employed. It will operate equally as well on a D.-C. power source.

The glow lamp passes a relatively heavy current and the parts of the switch 8 are made of relatively light construction so that an extremely fast repetitive action of the switch is obtained. In spite of this fast action, the starter stops operation instantly when the lamp lights because the glow lamp will not pass current at the voltage existing across a lighted lamp.

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

A starter for discharge lamps comprising, in combination, a glow discharge device adapted to pass current when subjected to a predetermined voltage and a magnetic switch having a series connected coil and normally closed contacts, said switch being electrically connected in series with said glow discharge device and being operable upon passage of a single impulse or repeated impulses of current through the device to interrupt the circuit through the starter.

2. A starter for discharge lamps comprising, in combination, a glow lamp adapted to pass current when subjected to a predetermined voltage and a magnetically operated switch having a coil and normally closed contacts electrically connected together in series with said glow lamp and being operable by passage of each impulse of current through said glow lamp to interrupt the circuit through said starter.

3. A starter for discharge lamps comprising, in combination, a glow discharge device adapted to pass current upon application of a predetermined voltage, a magnetically operated switch having a coil and normally closed contacts electrically connected together in series with said glow discharge device and being operable upon passage of a single impulse or repeated impulses r. of current through said device to interrupt the circuit through said glow switch, and a capacitor electrically connected in parallel with said glow discharge device and said magnetically operated switch.

4. A starter for electric discharge lamps comprising, in combination, a glow discharge device adapted to pass current when subjected to a predetermined voltage, a magnetic switch having a series connected coil and normally closed contacts, said switch bein electrically connected in series with said glow discharge device and being operable upon passage of current through the device to interrupt the circuit through the starter, and means electrically connected in circuit with said switch and being responsive to voltage across the lamp to interrupt the circuit through the starter in the event that the lamp fails to light.

5. A starter for use in an operating circuit for a discharge lamp including a ballast and a source of power and adapted to be connected between the lamp electrodes comprising, in combination, a glow discharge device, and a magnetic switch, said switch having normally closed contacts and an operating coil therefor, said coil and contacts being electrically connected together in series with each other and with said glow discharge device, said glow discharge device being operative upon application of power to energize said magnetic switch whereby the magnetic switch is operated to open the contacts to apply a high 7 voltage from the ballast across the lamp electrodes to'start the lamp, .said'glow discharge device being inoperative upon starting of the lamp to open' the circuit to said magnetic switch.

'6. A starter for an electric discharge lamp comprising, in combination, a voltage sensitive glow discharge device and a magnetic switch having a series connected coil and normally closed contacts, said switch being electrically connected in series with said glow discharge device and being operable upon passage of a single impulse or repeated impulses of current through the device to interrupt the circuit through the starter for :producing high voltage impulses for starting said lamp, the periods during which the contacts are 15 2 393, 32

open being shorter than the deionization time of the arc discharge in said lamp.

LEONARD W. COOK.

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

UNITED STATES PATENTS 10 Number Name Date 2,212,427 Peters Aug. 20, 1940 2,270,368 Zecher Jan. 20, 1942 2,341,520 Babb Feb. 15, 1944 2,394,436 Frech Feb. 5, 1946 Whiteside Apr. 16, 1946