US2721296A - Instant-start high power factor fluorescent-lamp device - Google Patents

Description

Oct. 18, 1955 'r. ASANO ETAL INSTANT-START HIGH POWER FACTOR FLUORESCENT-LAMP DEVICE Filed June 16, 1950 Fig- I- ji ll O. TE/?AMUEA INVENTORS A TTORNEYS United States Patent INSTANT START HIGH POWER FACTOR FLUORESCENT-LAMP DEVICE Torn Asano, Tokyo-to, Kunio Sato, Kanagawa-ken, and Osamu Teramura, Tokyo-to, Japan, assigno'rs to The Governor of Tokyo-Metropolitan Olfice, Tokyo, Japan Application June 16, 1950, Serial No. 168,466

3 Claims. (Cl. 315-97) The present invention relates to an instantaneous starting, high power factor fluorescent lamp arrangement, in which each of the two electrodes is connected, respectively, with the intermediate point of a selected impedance circuit consisting of an inductive and a capacitative impedance (that is, an inductance and a condenser), wherein the series connection of the inductive and capacitative impedances of the one impedance circuit is inverse with respect to that of the other impedance circuit and the said two circuits are connected at their outer terminals in parallel arrangement with a supply voltage. The arrangement is further characterised by an inductive impedance connected between one terminal of the supply voltage and a terminal of the parallel connected impedance circuit and that the metallic reflector of the fluorescent lamp is connected through a condenser and a resistance with the supply circuit at a point, the potential of which is materially different from that of at least one electrode at the instant of starting of the lamp.

But the starting switch has various defects that it is liable to receive any damage and its reliability is relatively low and also it can not let start directly the fluorescentlamp designed for high voltage, for example, 200 volts when relative low voltage, for example, 100 volts is used as the supply voltage. And at the other hand the device provided with a step-up transformer oran autotransformer becomes relatively large type and expensive type and its treatment is troublesome. And also at the above said both cases there are other defects that the power factor of the device is relatively low and it is impossible to maintain the power factor in any desired value.

The main object of this invention is to provide an improved fluorescent-lamp device, at which not only the fluorescent-lamp designed for normal low voltage, for example, 100 volts, but also the fluorescent-lamp designed for high voltage, for example, 200 volts can be started directly and securely without various above said defects, that is, without using any starting switch or separate stepup transformer or autotransformer.

Furthermore the other object of this invention is to gain a fluorescent-lamp device which can operate always with any high power factor and high efficiency.

According to this invention it is possible to gain very excellent etfects that, as is clear from the after minute description, not only the fluorescent-lamp as the 40 watt lamp or more high watt lamp designed for 200 volts, but also the Slimline type lamp designed for over 300 volts can be directly and effectively started even when 100 volts is used as their supply voltage and also such lamp can operate always stably even when the supply voltage varies or decreases relatively large amounts during its operation.

Further objects, principle, operation, and the advantages of this invention will be apparent from the following description taken in connection with the accompanying examples and their drawings, wherein:

Fig. l is a diagrammatic connection diagrams of an example in which only one fluorescent-lamp is used.

Fig. 2 is a vector diagram describing the operation of the example at the Fig. 1.

Fig. 3 is a diagrammatic connection diagram of the other example at which three fluorescent-lamps connected in series are used.

At the Fig. l, 1, 2 are terminals to be connected with the supply voltage V0 and with these terminals are connected in parallel with each other two electric circuits, the one of which is made of an inductive impedance 2'1. and a capacitive impedance Zc connected in series and in order from the connection point 3 towards another connection point 6 and another circuit is made of a catpacitive impedance Zc and an inductive impedance Z1. connected in series and in order from the point 3 towards the point 6. At this time the impedances Z'L, Z'c, Z"1., Zc are so selected that at the frequency of the supply voltage a kind of series resonance condition will occur respectively in each of the both parallel circuits. 4 is a fluorescent-lamp and its one electrode 5 is connected with the intermediate point, between the impedance ZL and Zo of one impedance circuit and with the intermediate point between the impedances Z1. and Z" of the other impedance circuit. Z is an inductive impedance, 10, 11, and 17 are condensers, 13 and 14 are heating terminals of the electrodes 5 and 6 of the fluorescent lamp, and 12, 15, 16, 18, and 19 are inductance coils. The metallic reflector of the lamp is shown in dotted lines at 8, and is grounded by a conductor 9. Shielding enclosures are shown around the impedances by dotted lines.

At the example of the Fig. 1, if we connect the terminals 1, 2 with a supply voltage, then a series resonance condition will occur in each of both parallel circuits consisted of the impedances Z'L, Zc and Ze, Z1., and large current will flow momentarily in each of the circuits. The voltage to be generated at this instant between the electrodes 5 and 7 may be cleared easily from the vector diagram of the Fig. 2. At this vector diagram, if we represent the supply voltage vector directed from the connection point 3 towards the connection point 6 by V0, the currents in the both parallel circuits by I, I" (at here we regard that the voltage and the currents are almost same phase, because each of the circuits is respectively in series resonance condition), the angular velocity of the supply voltage by w, the resistances of the inductive coils 12, 15, 16, 18, and 19, by R12, R15, R16, R13 and R19 respectively the inductances of the inductive coils '12, 15, 16, 18, and 19, by L12, L15, L16, L18, and L19, respectively and the capacities of the condensers 11 and 17 by C11 and C17 then each of the vectors of the voltages across the components 15, 16, 17, 11, 12, 18, and 19, becomes respectively, R15I'-:jwL15l', R16l':]'wL16I',

R12I"+jwL12I", R1sI"-:-jwL1sI, R19I+jwL19I as is shown in Fig. 2. The voltage between the electrodes 5 and 7 becomes to the value designated by the vector V1. At this time the currents I, I" are relatively large, so that if we select properly the value of each element of the impedances, then the voltage VT between the electrodes 5 and 7 of the fluorescent-lamp 4 would become greatly higher than the supply voltage Vo.

A numerical example according to the arrangement of Fig. 1 is as follows: If a w. fluorescent lamp is used and the supply voltage is 100 volts and the frequency 50 cycles, the values of the resistances R12, R15, R16, R18 and R19 should each be about 40 ohms, the reactance values of the inductances L12, L15, L16, L18, and L19 should each be about 80 ohms, and the reactance values of the condensers 11 and 17 should be about 400 ohms, respectively. The vector diagram of the arrangement according to Figure 1 then becomes as is shown in Figure 2, wherein the voltage Vo of 100 volts is taken as the standard reference vector. Therefore, as is clear from Fig. 2, the voltage VT betwen the electrodes 5 and 7 becomes approximately 200 volts, the voltage V being on 100 volt scale.

As the result of the above stated conditions, at the same time of application of the supply voltage the fluorescent lamp 4 will start automatically and with certainty. Such instantaneous starting is due to the high voltage between the electrodes and 7.

However, in spite of the above described certain starting, it will often occur that an undesired flickering will take place owing to the unbalance of the currents I and I in the parallel impedance circuits and to the high harmonic currents in the circuits. Such disadvantages, according to the present invention, can be eliminated by a special impedance Z, properly connected in the circuit. That is, the said unbalance and the various harmonic currents will be effectively suppressed by the impedance Z, resulting in the elimination of any flickering.

On the other hand, notwithstanding the generation of the high voltage between both electrodes of the fluorescent lamp during starting, it occurs occasionally that the lamp will not start instantly.

According to the present invention, however, the previously stated defect can be effectively eliminated by connecting, as shown in Fig. l, the reflector 8 of the lamp with a point in the supply circuit having a potential which is substantially diiferent by a relatively large amount from that of the electrode, or electrodes. For example, such connection can be to a terminal point 1 of the supply voltage circuit, as through a condenser 10 to ground through a ground conductor 9. According to such connection of the reflector, as any grow discharge generated will be effective in to the region near the electrode, at

the instant of flowing of the currents l and I, owing to the capacitative current between said electrode and the reflector 8, so then can thelamp start securely without any lag. For example, if a condenser with 0.01 ,uf. capacity is used as the condenser Till, then the lamp can start on a supply voltage of only about 25 volts even when the lamp usedis designed for operation on 100 volts.

According to the example of the Fig. l, as is clear from the description at the above part, any fluorescent-lamp can be brought securely and automatically into discharging condition without using any starting switch or step-up transformer and not only 26 watt fluorescent lamp for 100 volts, but also watt or more high watt fluorescentlamp for 200 volts can be started Without any starting switch even when 80 volts or more low volt is used as the supply voltage and also after starting it would not go out even when the supply voltage decreases into very lower voltage as 20 volts. And then specially great increment of the current would not occur during its normal operation even when the supply voltage increases in order of 200%, because at the nonrescnance condition after starting relative large impedances may be inserted into the circuits. Furthermore it would be possible to maintain the power factor of the fluorescent-lamp device in almost 100% or to maintain freely the load current in leading condition by means of proper design or variation of the value of the imp'edances ZL', Zc and Z0, ZL. And then it would be possible to gain any fluorescent-lamp device having no flicker of the stroboscopic-phenomenon by means of combination of two or three lamp devices, of which lamps have discharging currents which are different with each other in their phase angles making with the supply voltage or by means of combination. of two same fluorescent-lamp devices, each of which is respectively connected under different polarity to the same supply voltage or by using any several fluorescent-lamp devices connected in polyphase system to a polyphase supply voltage.

The fluorescent-lamp device as is described in respect to the Fig. 1 can be operated effectively with each of 60 cycle voltage and 50 cycle voltage and can be used for 20 watt lamp, 40 watt lamp (or more high watt, 100 watt, lamp) or several 20 watt lamps connected in series. And then the device of this invention can operate independently of the surrounding temperature and for example can operate effectively at temperature of l5 C. So that it can be used eifectively for any street-lighting. On the contrary at any well-known former fluorescent-lamp device, it is usual that its operation becomes unstable as soon as the surrounding temperature decreases within lower temperature as 0 C. But according to this invention such defect can be removed effectively. And then power loss of the lamp device of this invention is very low, because there is only very few ohmic resistive elements in the operating electric circuits.

At the embodiment of this invention as is described already, not only a fluorescent-lamp, but also several fluorescent-lamps can be used for a device and an example, at which three lamps are used in series condition, is shown in the Fig. 3. At the Fig. 3, the impedance components designated by the same symbols as on Figure l are likewise so designated on the modification shown in Fig. 3. The reference numerals 4', 4", 4 designate three hotcathode type fluorescent-lamp connected in series at their hot-cathodes and each pair of their series connected hotcathodes 5, 7' is so connected with the corresponding auxiliary coil 20 coupled inductively with the iron core of the corresponding inductance coils l5 and 18 in the resonance circuits that they can be heated by the auxiliary coil 20. Of course at this example, it may be allowable to use an auxiliary coil, coupled inductively with the iron core of the outside impedance Z in order to heat the hot-cathodes 5', 7. The operation of this example is same exactly with. that of the example of the Fig. 1.

As a whole, the fluorescent-lamp device of this invention, as is clear from the above description, can be used effectively under using, any supply voltage of which voltage may vary frequently between volts and 250 volts and also for every kind of 20 watt lamp, 30 watt lamp, 40 watt lamp, and watt lamp. And then the device can be used effectively for any Slimline type and coldcathode type lamp by means of proper variation of the impedance value. Furthermore the power factor of the device can be maintained in desirable value, for example in almost 100% in spite of great variation of the supply voltage during operation. And also it is possible to eliminate the flicker of the stroboscopic phenomenon by means of combination of several fluorescent-lamps having different phase angle.

When the device of this invention should be applied for any car-lighting, if we use an alternating current voltage gained through an inverter from a direct current voltage, then the device would be effectively applied for any car-lighting, And also when the device should be applied for any stage-lighting, then the adjustment of the light would be easily done by means of an induction regulator.

The device of this invention may be also operated effectively by high frequency supply voltage.

point between the said inductive and capacitive imped ances of each of the said impedance circuits, an impedance connected in series with the parallel impedance circuits and to one terminal of the source of alternating supply voltage, and a reflector for the lamp connected with a point in the supply circuit having a potential which is substantially different just before starting by a relatively large amount from that of the electrodes.

2. In an arrangement for instantaneous starting and operation at high power factor of a fluorescent lamp from a source of an alternating supply voltage wherein two impedance circuits consisting of series-connected inductive and capacitive impedances are connected in parallel with said supply voltage and each of outermost electrodes of the several fluorescent lamps connected in series is connected respectively with an intermediate point between the said inductive and capacitive impedances of each of the said impedance circuits, an impedance connected in series with the parallel impedance circuits and to one terminal of the source of an alternating supply voltage, and a reflector of the lamp connected with a point in the supply circuit having a potential which is substantially different, just before starting, by a relatively large amount from that of the electrode or electrodes.

3. In an arrangement for instantaneous starting and operation at high power factor of a fluorescent lamp from a source of an alternating supply voltage as claimed in claim 1, a secondary coil inductively coupled with one of the inductive impedances in one of said parallel branch circuits and connected to the electrodes of said fluorescent lamp.

References Cited in the file of this patent UNITED STATES PATENTS 2,333,499 Warren Nov. 2, 1943 2,428,646 Boucher Oct. 7, 1947 2,462,336 Ruff Feb. 22, 1949

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