US3397343A - Plural lamp starting circuit utilizing high impedance and glow discharge switch to cause the lamps to act as ballasts - Google Patents

Description

Aug. 13, 1968 SHUNGO FURUI 3,397,343

PLUHAL LAMP STARTING CIRCUIT UTILIZING HIGH IMPEDANCE AND GLOW DISCHARGE SWITCH TO CAUSE THE LAMPS TO ACT AS BALLASTS Filed March 6, 1967 FIGI INVENTOR SHUNGO FURUI ATTQRNEY United States Patent "ice PLURAL LAMP STARTING CIRCUIT UTILIZING HIGH IMPEDANCE AND GLOW DISCHARGE SWITCH TO CAUSE THE LAMPS TO ACT AS BALLASTS Shungo Furui, Yokohama, Japan, assignor of twenty-five percent to Yasnka Akamatsu, Sacramento, Calif. Filed Mar. 6, 1967, Ser. No. 621,737 4 Claims. (Cl. 315189) ABSTRACT OF THE DISCLOSURE This invention relates to a circuit for starting two or more gaseous discharge lamps which are connected in series to a voltage source, comprising impedance means connected in parallel to one of said lamps, and switch means connected in series with said impedance means and in parallel with another of said lamps and operable to initially short circuit said other lamp thereby to start said one lamp and to subsequently remove said short circuit to cause said other lamp to start.

This invention relates generally to starter circuits for gaseous discharge lamps, and more particularly to such circuits which are useful in lighting systems having negative resistance effect lamps and/or lamps having heavy current requirements, such as for example mercury vapor lamps and fluorescent lamps.

One of the problems involved in starting gaseous discharge lamps, such as mercury vapor lamps, is the high initial voltage required to vaporize the metal (for example, in the case of mercury vapor lamps) or to ionize the gas (for example, in the case of fluorescent lamps) in order to give the gas or vapor molecules sufficient energy to travel between the electrodes of the lamp and cause current to pass therebetween. However, once the lamp is lit, there is a negative resistance effect, that is a surge of current results immediately because of the high voltage and low resistance between the two electrodes once the arc therebetween is connected. Unless this current is controlled, the lamp and auxiliary equipment would be irreparably harmed. In the prior art types of starting circuits, a ballast in the form of a large resistance or inductor is placed in series with the lamp to absorb the excess "current and thus reduce the negative resistance effect. These prior art techniques are expensive both in terms of initial cost of manufacture and operating power. Also, malfunctioning of the resistance or inductor can result in destruction of the lamps.

Accordingly, it is an object of this invention to resolve the foregoing problems. More specifically, an object of this invention is to reduce the magnitude of the starting voltage thereby reducing the voltage requirements of the equipment and lessening the voltage required to be attenuated during the operation of the lamps.

Another object of this invention is to insure that malfunction of the starting circuit will not result in excessive flow of current.

A further object of this invention is to reduce the operating power requirement of gaseous discharge lamp systems.

Other objects of this invention are to eliminate any need for voltage attenuation, to improve power factor, to lessen cost of manufacture, to improve voltage and current regulation, and to improve the performance of gaseous discharge lamp systems.

These and other objects are attained in this invention which may be used to sequentially start a plurality of gaseous discharge lamps, such as for example, mercury 3,397,343 Patented Aug. 13, 1968 vapor lamps. Briefly, the invention comprises a high resistance connected across one of the lamps, and a novel starter switch arrangement connected across another of the lamps in such a manner that initially when the voltage is placed into the lamp circuit the said other lamp is short circuited thereby enabling the one lamp to be started and immediately thereafter the switch removes the short circuit thus connecting the two lamps in series across the voltage source and the high resistance and starter switch are connected in series to each other and in this manner the negative resistance effect of the one lamp enables the other lamp to receive suflicient voltage to be started. The lamps effectively act as ballasts for each other and enable sequential starting of the lamps. Malfunctioning of the switching circuit would not be harmful since the maximum current is limited to the normal lamp current.

The voltage source may be a transformer connected in series with a capacitor and the lamps. In this way, by suitable use of appropriate equipment, automatic voltage regulation is obtained. Even though the series capacitor may be short circuited, because of the lower starting voltage, the current will not reach a dangerous level.

One feature of this invention is a novel switching circuit and high resistance connected across two or more gaseous discharge lamps and operable in such a manner as to initially place a short circuit across one of the lamps and thereby start the other lamp and subsequently remove the short circuit and place the other lamp in series circuit with the one lamp and thereby enable the one lamp to be started.

Another feature of this invention is the elimination of ballast voltage for starting and operating the lamps. A transformer having a secondary connected to the lamps in combination with the novel switching circuit enables both starting and operation of the lamps without voltage attenuation.

These and other features and objects of this invention will become more evident upon consideration of the following detailed description of illustrative embodiments of this invention and drawing, in which:

FIG. 1 depicts an illustrative embodiment of this invention as used with mercury vapor lamps, and

FIG. 2 depicts another illustrative embodiment of this invention as used with heavy current rapid start type fluorescent lamps (LFR).

In FIG. 1, there are shown two mercury vapor lamps 3 and 4, both having two opposite electrodes therein. One electrode of lamp 3 is connected to terminal 13 of the primary winding 1A of transformer 1. The other electrode of lamp 3 is connected in series with one electrode of lamp 4. The other electrode of lamp 4 is connected to terminal 15 of the secondary winding 1B of transformer 1, via capacitor 2. Capacitor 2 is shunted by a high resistance 10. Resistance 9, which is of relatively high value, is connected in shunt to lamp 3.

Coil 7B of the magnetic relay switch 7 is connected in series with the glow starter switch 6, both of which being connected in parallel with lamp 4 in the manner depicted. Resistance 9, coil 7B and glow starter switch 6 are connected in series as depicted. One contact 7B of the magnetic relay switch 7 is connected to resistor 9. Contact 7F is connected to terminal GB of the glow starter 6. Glow starter switch 6 may be shunted by a noise suppressor capacitor 11.

The autotransformer 1 may have a winding 1A (primary) having terminals 13 and 14, and a winding 1B (secondary) having terminals 13 and 15. The primary and secondary windings may be wound on the same core.

The transformer 1 differs from an ordinary leakage type transformer insofar as its no-load secondary voltage is relatively low. Thus voltage attenuation is also relatively low. It may have a leakage pass depending upon the design criteria used. A proper amount of leakage pass does not prevent proper functioning of the transformer since the voltage attenuation is comparatively small as would be evident to the worker in the art. However, a proper distribution and placement of the secondary winding 13 on the core is important to obtain the best performance.

The value of the capacitor 2 may be selected to give a rated lamp current when the rated primary voltage is applied.

The mercury vapor lamps 3 and 4 may be of any suitable type known in the art, for example such as those filled with mercury vapor about at 1 to 4 atmosphere pressure with inert gas and having oppositely disposed electrodes and other subsidiary mechanisms.

The glow starter switch 6 may be any known normally open type switch having bimetal contacts which are closed by heat resulting from the gaseous discharge of the gas contained therein. After the switch contacts are closed by the heat initially produced by the gaseous discharge, the bimetal element is allowed to cool and return to its normally open position. In this manner the switch 6 is closed and opened.

In the present invention, the glow starter switch 6 may be used in combination with a magnetic relay switch 7 to produce the special starter switch 5.

The magnetic relay switch 7 comprises a magnetic core 7A, coil 7B wound about the core, an armature 7C being supported by pin 7D, and contacts 7E and 7F operable by the armature extension 7C.

Upon application of a suitable voltage between the terminals 7E and 6E, a gaseous glow discharge is produced at the contacts of the glow starter switch 6. The heat produced therefrom causes the bimetal contactor 6C to warp and engage with the contact 6B. This causes an energizing current to flow through the coil 7B, thus attracting the armature 7C and thereby closing contacts 7E and 7E.

The function of resistor 9 is to supply the starting voltage or glow discharge current to the glow starter switch 6. Its value should be sufficiently low to cause a glow discharge in the tube 6, and at the 'same time be suffi ciently high to prevent short circuiting of lamp 3. A suitable value may be about 10,000 ohms. The resistance 9 is only illustrative and may instead be any high impedance such as a capacitor or an inductor. In general, a high impedance capacitor appears to give a good performance and a simple resistor is economical and safe.

The symbol 8 represents a base on which the magnetic relay 7 and/or the special starter switch and glow switch 6 may be positioned.

In the operation of the invention, the lamps are caused to be lit by closing switch S. Transformer 1 is energized and a no-load secondary voltage or starting voltage is applied to the series connected lamps 3 and 4. Simultaneously, the starting voltage is applied to glow starter switch 6 through resistor 9 to produce a glow discharge between the contacts of switch 6 thereby causing its bimetal element to warp and move toward its closed position. During this movement of the switch element, neither one of the lamps 3 and 4 are lit. However, when switch 6 closes, an energizing current flows through coil 7B of relay 7 thereby pulling armature 7C downward to cause contacts 7E and 7F to close. This elfectively short-circuits lamp 4. Thus lamp 4 no longer acts as a voltage dropping element for lamp 3, and the entire starting voltage is applied to the lamp 3 causing it to start.

When lamp 3 is lit, the bimetal contactor 6C becomes cooled and the contacts open thereby turning off the energizing current to coil 7B. This in turn opens the contacts 7E and 7F to remove the short circuit from lamp 4. The starting voltage acts directly on both lamps 3 and 4. Since lamp 3 has low impedance at this point, -sufficient voltage is placed across the electrodes of lamp 4 to cause it to be started almost instantaneously. The impedance of coil 7B acts to prevent starting of lamp 3 before the contacts 7E and 7F are closed. Once lamps 3 and 4 are lit, they may be extinguished by opening switch S.

Thus, the operation is substantially instantaneous. As is evident from FIG. 1, magnetic relay 7 operates only when the glow starter switch 6 is closed. Operation of the relay 7 is noiseless while lamps 3 and 4 are lit. The relay 7 may be of either a DC. type or an A.C. type.

The lamps 3 and 4 are lit sequentially, first being lamp 3 then lamp 4. When lamp 4 is lit, its resistance becomes relatively small and the voltage developed across its electrodes is insufficient to produce a glow discharge between the contacts of glow starter switch 6.

The starting voltage, i.e., the voltage developed across the terminals 13 and 15, is relatively 'small and may be below 300 volts when the lamps 3 and 4 are of 200 watt capacity. The glow starter switch may be of the FG-4P or FG-8P types.

Because the resistances of lamps 3 and 4 are high during their unlit condition, the resistor 9 being of a particularly, for example 10,000 ohms, assures an initial discharge between the contacts of glow switch 6 before any of the lamps is lit. When the contacts of switch 6 close the high resistance offered by the unlit lamp 4 is effectively short circuited thereby causing a starting voltage to be developed between terminals 13 and 6E, thereby starting lamp. 3. When lamp 3 is lit, its resistance effectively short-circuits resistor 9, thereby transferring the higher starting voltage across terminals 7E and 6E sufficient to start lamp 4.

The voltage supplied to lamps 3 and 4 is utilized for two purposes, first as a ballast voltage for starting the other lamp, and second for operating the lamp itself after it is started. In this manner, the magnitude of the starting voltage may be relatively small as compared to prior art methods of starting gaseous discharge lamps. FIG. 1 does not show the magnitude of the starting voltage. However, the value of the starting voltage constitutes one of the important advantages of the present arrangement.

Advantageously, the use of relatively small starting voltage per lamp in the present invention permits use of small sized, lighter, and more economical ballasts. Furthermore, the consumption of power is reduced, thus making any lighting system using this invention more economical to operate. As is evident from FIG. 1, the ballast voltage which may be saved is equivalent to the lamp voltage of one lamp, and the net ballast voltage required in addition to the sum of the lamp voltages is equivalent to the reserve voltage required to insure against line voltage drop.

Turning now to FIG. 2, there is depicted another application of the present invention for heavy current rapid start type (e.g., LFR) fluorescent lamps. The foregoing description of FIG. 1 may be applied to FIG. 2. The like symbols used in FIGS. 1 and 2 identify like elements. In addition, symbols 1C, 1D, 1E are filament heater winding of transformer 1. Numbers 3 and 4 denote, in FIG. 2, fluorescent lamps with their filaments denoted 3A, 3B and 4A, 4B, and their static shields denoted 12 and 12A respectively. The shields are ground connected as depicted. The filaments 3A, and 3B, 4A, and 4B are heated by filament windings 1C, and 1D, and 1E respectively in the manner depicted in FIG. 2.

The operation of the circuit of FIG. 2 is similar to that described in connection with FIG. 1. When switch S is closed, filaments 3A, 3B, 4A and 4B are heated, and a glow discharge appears in glow switch 6 thus heating the bimetallic element therein which moves to its closed position. When switch 6 is thus closed, an energizing current flows through coil 7B causing the armature 7C to be moved toward the core. This movement causes the lower lever to move leftward and cause contacts 7E and 7F to close, thus shortcircuiting lamp 4. This causes the starting voltage to be applied to lamp 3, thereby causing it to be lit almost instantaneously. The lamp 3 thus being lit, the bimetallic element of glow switch 6 becomes cooler because of the extinguishing of the glow discharge therein.

When the bimetallic contactor cools, the contacts of switch 6 are opened to cut off energizing current from coil 7B of relay 7. This causes contacts 7E and 7F to open. Thus, the starting voltage is directly applied to both lamps 3 and 4, but since the resistance of lamp 3 is reduced, substantially all of the starting voltage is now applied to lamp 4, causing it to be lit.

Although the present invention was described in terms of an illustrative embodiment, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the spirit and scope of this invention.

What is claimed is:

1. In a lighting system, a first discharge device, a second discharge device, a first impedance means of relatively high value connected in parallel with said first discharge device, a starter switch means connected in parallel with said second discharge device, said starter switch means comprising a glow switch and a magnetic relay, said glow switch being connected in series with said magnetic relay and comprising a normally open switch and means responsive to heat produced therein from a glow discharge for causing said normally open switch to close, an energy source, means connecting said energy source, said first discharge device, and said second discharge device in series circuit, said first impedence means being effective to prevent lighting of said second discharge device when said means for connecting initially connects said energy source into said series circuit to cause a glow discharge to appear in said glow switch whereby said normally open switch is caused to close and said magnetic relay is caused to close thereby short circuiting said second discharge device and causing said energy source to apply to said first discharge device sufiicient energy to cause its lighting, said glow switch thereby being caused to open whereby said magnetic relay is opened thereby removing said short circuiting from said second discharge device and said energy source to apply sufficient energy to both said discharge devices to cause said second discharge device to light.

2. The system of claim 1, wherein said first impedence means comprises a resistor of relatively high value.

3. The system of claim 1, wherein said first and said second discharge devices are mercury vapor lamps.

4. The system of claim 1, wherein said first and said Second discharge devices are fluorescent lamps.

References Cited UNITED STATES PATENTS 1,942,078 1/1934 Westendorp 315-190 X 2,423,031 6/1947 Kurtz et al 315--100 X 2,491,858 12/1949 Hehenkamp et al. 315-10O X 2,859,386 11/1958 Van Dusen 315-189 3,351,809 11/1967 Eppert 315-185 JAMES W. LAWRENCE, Primary Examiner.

C. R. CAMPBELL, Assistant Examiner.

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