US2842715A

US2842715A - Fluorescent lamp lighting circuits

Info

Publication number: US2842715A
Application number: US448426A
Authority: US
Inventors: Wilson A Charbonneaux
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-08-09
Filing date: 1954-08-09
Publication date: 1958-07-08
Anticipated expiration: 1975-07-08

Description

July s, 1958 Filed Aug. 9, 1954 W. A. CHARBONNEAUX FLUORESCENT LAMP LIGHTING CIRCUITS INPUT 2 Sheets-Sheet 1 FIG. 2..

EF (EFFECTIVE LAMP VOLTAGE LAMP STARTS INVENTOR WILSON A. CHARBONNEAUX AT TORNEY y 1958 w. A. CHARBONNEAUX 2,

FLUORESCENT LAMP LIGHTING CIRCUITS Filed Aug. 9, 1954 2 Sheets-Sheet 2 C S 4 k HM m FIG.4. 4

LIPIGE F /C 2} H L 7 R5 B 9 FIG. 5.

I FIG. 6.

Hid/2i 1 FIG 7 INVENTOR. WILSON A. CHARBONNEAUX e Aww W ATTORN EY United States Patent FLUORESCENT LAMP LIGHTING CIRCUITS Wilson A. Charbonneaux, Dayton, Ohio Application August 9, 1954, Serial No. 448,426

3 Claims. (Cl. 315-184) This invention relates to certain new and useful improvements in fluorescent lamp lighting circuits.

At the present time, fluorescent and similar gas-filled discharge-type lamps for interior illumination in homes, plants, factories, and warehouses are conventionally used with a ballast which provides a momentary high starting voltage necessary to initiate ignition in such lamps. The ballast, furthermore, operates to limit operating voltage subsequent to ignition. Such ballasts conventionally comprise a combined auto transformer and choke and consequently possess several disadvantages, such as a continuous high power loss, a lagging power factor which adds to the normal lagging power factor of other loads, and temperature rise during operation which creates insulation problems and limits practical use to conventional 110 v. and 240 v. lighting circuits despite the fact that great economies in installation and operating costs could be achieved with higher line voltages.

It is, therefore, the primary object of the present invention to provide fluorescent lighting circuits by which fluorescent lamps and similar devices can be started promptly and efliciently across high voltage circuits and operated with a minimum of current consumption and power loss.

It is another object of the present invention to provide fluorescent lighting circuits which are substantially more economicalthan existing fluorescent lighting circuits, both as to initial installation costs, as well as operating costs.

It is a further object of the present invention to provide fluorescent lighting circuits by which a multiplicity of fluorescent lamps can be lighted and economically operated on higher voltage circuits, that is to say, for instance, a 440 v. circuit and similar circuits of the type usually available in industrial plants.

With the above and other objects in View, my invention resides in the novel features of form, construction, atrangement, and combination of parts presently described and pointed out in the claims.

In the accompanying drawings (two sheets) Figure l is a schematic wiring diagram of a fluorescent lighting circuit embodying the present invention; 7

Figure 2 is a graph showing the voltage relationship in the circuit of Figure l; and

Figures 3, 4, 5, 6, and 7 are modified forms of fluorescent lighting circuits embodying the present invention.

Broadly speaking, the present invention resides in the discovery that fluorescent lamps and similar devices having similar starting and running characteristics can be very efliciently started at ordinary room temperature and even at lower ambient temperatures by the utilization of an A. C. series circuit consisting of a capacitor and current limiting impedance in series with the lamp and a shunt circuit around the lamp, which latter circuit includes a rectifier. The rectifier is preferably of the cold-cathode gaseous discharge type and will provide a peak instantaneous voltage of approximately twice the instantaneous peak value of the A. C. line voltage, due to the fact that the capacitor remains charged only during successive half cycles of opposite polarity. Since the lamp acts as a very high resistance element before lighting, the capacitor will remain charged to its maximum potential until the lamp lights. This potential builds up in the capacitor until it is sufficiently in excess of the ionization voltage of the lamp to cause the lamp to flash and become lighted. Several half-cycles may be required depending upon the impedance of the reactor or other current limiting device, the impedance of the rectifier, and the time-constant of the circuit. Since the maintenance or operating potential of such a lamp is much lower than its ionization potential, the lamp will be maintained in lighted condition on ordinary line voltage. In this connection, it should be noted that all references herein to a line" imply an A C. line.

Referring now in more detail and by reference characters to the drawings, which illustrate practical embodiments of the present invention, Figure 1 schematically represents a fluorescent lamp lighting circuit comprising an inductive reactor L, a rectifier R, a capacitor C, a single pole single throw switch S, and a fluorescent lamp F, all being connected as shown.

As soon as voltage is applied across the line and the switch S closed, current will flow through the inductive reactor L, capacitor C, and thence through the rectifier R around the lamp F to complete the circuit. The instantaneous voltage. rises to the firing potential of the rectifier R, thus charging the capacitor C. If the lamp F does not light at this value of potential, the charge remains on the capacitor C. Assuming the capacitor has charged to full peak-value, then on the next cycle the lamp will have twice the peak-value of line voltage upon it at the peak of the next half cycle. When the lamp lights, the voltage drop across it will return to the operating value which is ordinarily one-half to one-third of the starting voltage.

If the voltage applied across the lines, for example, is 440 v., cycle, the rectifier R should be designed to have an initial firing potential somewhere between the starting and operating voltages of the lamp, that is to say, somewhere in the range of 425 v. to 475 v. and it will pass charging current when the instantaneous value of each positive half-cycle approaches such firing potential. Thus, the rectifier R operates as a regulating valve to pass charging current to the capacitor C during each positive half-cycle (or negative half-cycle, depending upon the arrangement of polarity within the circuit), but the rectifier R does not allow the capacitor C to discharge. Hence, the charge in the capacitor C builds up until a D. C. potential is reached suflicient to cause the fluorescent lamp F to start on a succeeding negative half'cycle. If the lamp F, for example, when connected in a circuit across a 400 v. line, has a starting potential requirement of 800 v. and an operating potential (after lighting) of only 200 v., the potential of the capacitor C (within a few cycles after closing the switches) adds to the A. C. voltage of the line, resulting ina total of twice peak voltage every cycle (2 400 1.41), thus furnishing more than suflicient voltage to light the lamp F. Immediately, however, with impedance of proper value, the lamp voltage would drop to 200 v. and the rectifier R would become inoperative. Figure 2 shows diagrammatically the voltage and current relationship with respect to time, as same occur in the circuit of Figure 1.

In the event the lamp F is inoperative, or is removed from its sockets, the rectifier R passes only suflicient current to maintain the charge on the capacitor C. No appreciable power is consumed, therefore, when the lamp F does not light. Furthermore, since the rectifier R does not operate at the lamp operating voltage, no power is consumed by the rectifier R when the lamp F is glowing.

Although the circuit implies use in connection with fluorescent lighting, the invention is not limited to fluorescent lighting, but extends to other devices having similar starting and running characteristics. Furthermore, the impedance L could be a resistance element, if desired.

Figures 3, 4, 5, 6, and 7, show modifications of the basic circuit above described, each including the lamp F, an impedance L, a capacitor C, and a switch S. The circuit of Figure 3, however, includes a rectifier R which has a starter anode connected to the cathode thereof. The circuit of Figure 4 includes a rectifier R which has a starter anode connected to the main anode thereof. The circuit of Figure 5 includes'a rectifier R which has a starter anode connected across the cathode and main anode by a voltage divider Z for control of the magnitude of the starter voltage. The circuits of Figures 6 and 7 include rectifiers R and R", respectively, which have starter anodes connected across the impedance L by voltage dividers Z and Z respectively, for controlling the amplitude and phase of the starter voltage.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the fluorescent lamp lighting circuits may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l. A circuit for fluorescent lamps and devices having similar load characteristics, said circuit comprising a fluorescent lamp, a reactor and capacitor in series with opposite terminals of the lamp, and a rectifier of the coldcathode gaseous discharge type shunted across the terminals of the lamp, said rectifier having a starter anode connected to its cathode.

2. A circuit for fluorescent lamps and devices having similar load characteristics, said circuit comprising a fluorescent lamp, a reactor and capacitor in series with opposite terminals of the lamp, and a rectifier shunted across the terminals of the lamp, said rectifier having a starter anode connected to its cathode.

3. A circuit for fluorescent lamps and devices having similar load characteristics, said circuit comprising a fluorescent lamp, a line connected to a source of current having a potential greater than the normal operating potential of the lamp but less than the ionization potential of said lamp, said lamp being connected across said line, an inductance and a'capacitor interposed on opposite sides of the line in series with the lamp, a shunt circuit around the lamp, and a rectifier of the cold-cathode gaseous discharge type interposed in said shunt circuit, said rectifier having a starter anode connected to its cathode.

References Cited in the file of this patent UNITED STATES PATENTS 2,130,077 Dorgelo Sept. 13, 1938 2,575,001 Bird Nov. 13, 1951 2,614,243 Clark Oct. 14, 1952