Electric lamp and discharge devices: systems – Condenser in the supply circuit – Inductance in the condenser circuit
Patent
1987-09-17
1989-10-24
Mis, David
Electric lamp and discharge devices: systems
Condenser in the supply circuit
Inductance in the condenser circuit
315291, 315DIG2, 315DIG5, 315DIG7, H05B 4114, H05B 4138
Patent
active
048764850
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention pertains to the general field of generators or ballasts that are used to ignite and sustain the illumination of ionic conduction lamps and more particularly to a ballast that generates a high frequency signal equal to the resonant ionic frequency of the lamp where the signal suffices to ignite and maintain the lamps illumination.
BACKGROUND ART
The development of ballast's for operating ionic conduction lamps has progressed from conventional ballasts that operate at a low 60 Hertz frequency to those that operate at frequencies from 10 Kilohertz to 40 Kilohertz.
The low frequency ballast is generally a series reactor transformer which includes a large number of windings. Thus, the ballast acts as a inductive device that serves to both ignite the lamp and to also limit the current to the lamp. Immediately after the lamp is ignited, the impedance of the lamp drops to a very low level and, hence, it is necessary to limit the current after ignition in order to avoid burning the lamp. The inductive reactance in the ballast operates to limit the current after ignition of the lamp.
There are many disadvantages inherent in the conventional low-frequency ballast. One is the weight and size factor of the ballast. Due to the heavy transformer, provisions must be made in each lamp fixture to mount and support the weight of the ballast. Another, because of the coil and core design of the transformer, the ballast will not start at temperatures below 52.degree. F. (11.1.degree. C.).
The transformer core in the ballast often tends to vibrate and generate a hum in the audible frequency spectrum. While this hum may not have a great amplitude, it is, nevertheless, distracting and uncomfortable. In combination with the hum, the ballast also produces a low frequency "strobe effect" that causes irritation and headaches in many persons. The strobe effect is particularly noticeable at the peripheral vision of the eyes.
Large capacitors are often times required to correct the power factor and phase displacement. These capacitors are relatively expensive due to their size and thus substantially increase the overall weight and cost of the ballast.
The inductive device in the ballast often generates a significant amount of heat. In many cases, when the lamp is not mounted in an environment where air flow can dissipate the heat, other means must be employed to dissipate this heat. Additionally, if the ballast is operated for an excessive period of time, the heat buildup may damage the ballast necessitating replacement.
One of the significant disadvantages of conventional ballasts is that the ballast requires a substantial amount of electrical power for its operation in order to ignite and thereafter maintain energization of the lamp. A substantial amount of power is required to ignite the ionic conduction lamp and after the lamp has been ignited, a lesser but continuing current source is applied to the lamp in order to maintain its energization. The high-frequency ballast is discussed in the following U.S. patents which do not read on the claims of the instant invention but are indicative of the present state-of-the-art:
______________________________________ U.S. Pat. No.
INVENTOR ISSUED
______________________________________
4,286,194 Sherman 25 August 1981
4,005,335 Pepper 25 January 1977
3,889,153 Pierce 10 June 1975
3,396,307 Campbell 6 August 1968
______________________________________
The Sherman patent discloses a ballast that functions at an operating frequency within the range of 22 to 25 Kilohertz. The ballast is designed to start and maintain energization and operation of a load which has a relatively high impedance during starting and a substantially lower impedance after starting and during operation. The load is generally an ionic conduction lamp including a phosphor excitable lamp such as a fluorescent lamp. The inventor of the instant improved ballast has the rights to the Sherman patent. In the process of experimenting with the design several problems were un
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patent: 4259614 (1981-03-01), Kohler
patent: 4277726 (1981-07-01), Burke
patent: 4288724 (1981-09-01), Sherman
patent: 4392085 (1983-07-01), Knoll et al.
patent: 4459516 (1984-07-01), Zelina et al.
patent: 4567404 (1986-01-01), Flugan
patent: 4806830 (1989-02-01), Veki
Cota Albert O.
Mis David
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