Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Discharge device load
Reexamination Certificate
1995-02-24
2001-01-09
Shingleton, Michael B (Department: 2817)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Discharge device load
C315S071000, C315SDIG007, C315SDIG004, C315SDIG005, C315S219000, C315S224000, C315S205000
Reexamination Certificate
active
06172464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to electronic ballasts for rapid-start fluorescent lamps, particularly where the lamps are powered via a series-resonant LC circuit.
2. Description of Prior Art
For a description of pertinent prior art, reference is made to U.S. Pat. No. 4,677,345 to Nilssen; which patent issued from a Division of application Ser. No. 06/178,107 filed Aug. 14, 1980; which application is the original progenitor of instant application.
Otherwise, reference is made to the following U.S. Pat. No. 3,263,122 to Genuit; U.S. Pat. No. 3,320,510 to Locklair; U.S. Pat. No. 3,996,493 to Davenport et el.; U.S. Pat. No. 4,100,476 to Ghiringhelli; U.S. Pat. No. 4,262,327 to Kovacik et al.; U.S. Pat. No. 4,370,600 to Zansky; U.S. Pat. No. 4,634,932 to Nilssen; and U.S. Pat. No. 4,857,806 to Nilssen.
SUMMARY OF THE INVENTION
Objects of the Invention
Objects of the present invention are those of providing for cost-effective electronic ballasts as well as compact screw-in fluorescent lamps.
This as well as other objects, features and advantages of the present invention will become apparent from the following description and claims.
Brief Description
The present invention is directed to providing improved inverter circuits for powering and controlling gas discharge lamps. The inverter circuits according to the present invention are highly efficient, can be compactly constructed and are ideally suited for energizing gas discharge lamps, particularly “instant-start” and “self-ballasted” fluorescent lamps.
According to one form of the present invention, a series-connected combination of an inductor and a capacitor is provided in circuit with the inverter transistors to be energized upon periodic transistor conduction. Transistor drive current is preferably provided through the use of at least one saturable inductor to control the transistor inversion frequency to be equal to or greater than the nature resonant frequency of the inductor and capacitor combination. The high voltages efficiently developed by loading the inverter with the inductor and capacitor are ideally suited for energizing external loads such as gas discharge lamps. In such an application, the use of an adjustable inductor permits control of the inverter output as a means of adjusting the level of lamp illumination.
According to another important form of the present invention, reliable and highly efficient half-bridge inverters include a saturable inductor in a current feedback circuit to drive the transistors for alternate conduction. The inverters also include a load having an inductance sufficient to effect periodic energy storage for self-sustained transistor inversion. Importantly, improved reliability is achieved because of the relatively low and transient-free voltages across the transistors in these half-bridge inverters.
Further, according to another feature of the present invention, novel and economical power supplies particularly useful with the disclosed inverter circuits convert conventional AC input voltages to DC for supplying to the inverters.
Yet further, according to still another feature of the invention, a rapid-start fluorescent lamp is powered by way of a series-resonant LC circuit; while heating power for the lamp's cathodes is provided via loosely-coupled auxiliary windings on the tank inductor of the LC circuit. Alternatively, cathode heating power is provided from tightly-coupled windings on the tank inductor; in which case output current-limiting is provided via a non-linear resistance means, such as an incandescent filament in a light bulb, connected in series with the output of each winding.
REFERENCES:
patent: 2139815 (1938-12-01), Fodor
patent: 2369767 (1945-02-01), Abernathy
patent: 2923856 (1960-02-01), Greene et al.
patent: 3263122 (1966-07-01), Genuit
patent: 4300073 (1981-11-01), Skwirut et al.
patent: 5164637 (1992-11-01), Nilssen
Dale et la. “Conversion of Incandescent Lamp Sockets to Fluorescent in the Home Market” Lighting & Design Application Mar. 1976 pp. 18-23.*
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