Electric lamp and discharge devices: systems – Three or more load devices connected between diverse pairs...
Patent
1994-04-28
1995-07-18
Pascal, Robert J.
Electric lamp and discharge devices: systems
Three or more load devices connected between diverse pairs...
315185R, 315209R, 315210, 315228, 315231, 315232, 315DIG5, H05B 3700
Patent
active
054344760
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a circuit arrangement for operating fluorescent lamps on a single-phase alternating voltage source without stroboscopic effects, whereby each lamp circuit has at least one inductivity and one starter device.
The fluorescent lamps used for lighting purposes in almost all spheres of technology, business or residential homes have the property that the luminous flux with the double frequency of the electric power feeding the fluorescent lamps oscillates, in a way still visible to the human eye. Such oscillation is perceived as glimmering and, when processes of rapid motion especially of rotating objects are observed, leads to stroboscopic effects, which may considerably interfere with the perception and cause optical illusions. Consequently, such light sources may pose a substantial hazard in the workplace. Furthermore, phenomena of fatigue and headaches often have to be attributed to such glimmering.
For reducing glimmering and the stroboscopic effects, it is known to connect each of the three fluorescent lamps in each case to one phase of the three-phase mains. This causes the luminous fluxes coming from said three fluorescent lamps to heterodyne in a way such that overall, a largely uniform luminous flux is obtained with a degree of uniformity .PHI. of about 0.95. However, three-phase current connections are not always available.
For avoiding glimmering and the stroboscopic effects, use is made in connection with single-phase alternating voltage sources of so-called duo-circuits, with which a degree of uniformity .PHI. of about 0.7 can be achieved, as compared to a single circuit (degree of uniformity .PHI. about 0.5 to 0.6).
The invention is based on the problem of further developing the circuit arrangement of the type specified above in a way such that the glimmering and the stroboscopic effects are avoided to the highest possible degree.
Said problem is solved on the basis of a circuit arrangement of the type specified above in that conductors of the single-phase alternating voltage source; capacitor is arranged in parallel with the first lamp circuit; and single-phase alternating voltage source and the point of connection of the inductive resistor and the capacitor of the series oscillating circuit, and a third lamp circuit is connected between said point of connection and the other conductor of the single-phase alternating voltage source.
Through the circuitry proposed in accordance with the invention it is possible to achieve in a single-phase alternating voltage network a light that is free of glimmering and stroboscopic effects to the highest possible degree due to overlapping of the light fluxes, as it can be obtained comparatively only in three-phase current installations. With the circuit arrangement according to the invention it is readily possible to obtain a degree of uniformity .PHI. of the luminous flux of 0.95.
Usefully, the phase displacement between the three lamp circuits amounts to 60.degree.. Owing to such phase displacement between the three lamp circuits, a particularly uniform luminous flux is obtained, whose oscillations are practically no longer perceivable to the human eye.
According to a particularly preferred embodiment, each lamp circuit has at least two fluorescent lamps connected by a duo-circuit. In this way, an even further increase in uniformity is achieved. The light coming from the six fluorescent lamps of such a circuit arrangement has an overall degree of uniformity of almost 1.
Two embodiments of the invention are explained in greater detail in the following by reference to the drawing, in which:
FIG. 1 schematically shows a wiring diagram of a circuit arrangement according to the invention for operating three fluorescent lamps; and
FIG. 2 schematically shows a wiring diagram of a circuit arrangement according to the invention for operating six fluorescent lamps, whereby two fluorescent lamps are combined in each case in pairs to form one duo-circuit.
The circuit arrangement shown in FIG. 1 has the three lamp circuits 1, 2 and 3, which are ar
REFERENCES:
patent: 3660716 (1972-05-01), Gorton
patent: 3725733 (1973-04-01), Mack et al.
patent: 4117377 (1978-09-01), Jimerson et al.
Pascal Robert J.
Ratliff Reginald A.
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