JPH0118556B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dimmer for a rapid starter type fluorescent lamp, and more particularly to a dimmer for a fluorescent lamp that keeps the electric power supplied to the filament constant and varies the tube current.

A fluorescent lamp dimmer is a device that adjusts the brightness of a fluorescent lamp to a desired value, and is used in homes, hotels, hospitals, halls, studios, supermarkets, and the like.

Conventional fluorescent lamp dimmers perform dimming by controlling the phase of an AC voltage source supplied to the fluorescent lamp and varying the time of the current flowing through the fluorescent lamp. but,
When dimming a fluorescent lamp, even if it is a rapid starter type that heats the filament,
As the time for the current to flow decreases, the thermoelectrons generated from the filament decrease, causing the tube current to become unstable and the dimming range to be 70% of the normal illuminance.
The light could only be dimmed up to a certain extent, and if you tried to dim it further, the wiring to the fluorescent lights would be complicated and some of the fluorescent lights would have to be thinned out and turned off.

SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks, it is an object of the present invention to provide a dimmer for a rapid starter type fluorescent lamp which has a wide dimming range by varying the tube current while keeping the electric power supplied to the filament constant.

For this purpose, in a fluorescent lamp lighting device equipped with a rapid starter type ballast, the device is connected between the input side of the rapid starter type ballast and an AC input voltage source, and the polarity of a part of the AC input voltage waveform is inverted. and a switch control unit that detects the phase of the waveform of the AC input voltage source as a synchronization signal and variably controls the on/off period of the plurality of switch elements. This is accomplished by a light dimmer.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and is a block diagram of a dimmer device for a rapid starter type fluorescent lamp.
FIG. 2 is a diagram illustrating the time chart for inverting a part of the sine wave waveform of the AC voltage and the average illuminance for the operation of each switch in the case of FIG.
A shows the commercial AC input voltage waveform, B shows the operating state of the switch, C shows the voltage waveform applied to the fluorescent lamp ballast, and D shows the average illuminance depending on the dimming state. Third
The figure is an explanatory diagram of the principle, and FIG. 4 shows the amplitude ratio of the fundamental wave and high frequency in the case of FIG. 3, respectively.

In the figure, 1 is a commercial AC input voltage source, 2 is a switch control unit, 3 is a rapid starter type ballast, 4 is a fluorescent lamp, S ₁ , S ₂ , S ₃ , S ₄ are switches, and e ₁ is a commercial AC input Voltage, e ₂ is the alternating voltage applied to the fluorescent lamp ballast,
T is a transformer, L is a chain coil portion, and θ is an angle representing 1/2 of the angle at which the voltage is reversed. In a rapid starter type ballast, when starting lighting, the choke coil L is coupled with the transformer T and functions as an autotransformer, and after lighting, the current increases and therefore works as a choke coil. The present invention utilizes the inductance characteristics of this chiyoke coil L. The present invention generates harmonics as shown in FIG. 4 by inverting the sinusoidal commercial AC input voltage at an angle of 2θ as shown in FIG. Figures 3 and 4 are examples of inverting the voltage at an angle of 2θ centered on the maximum value of the sine wave commercial AC input voltage. This shows that the third harmonic is at its maximum. This shows that harmonics are generated even if the maximum value of the sine wave is not the center, and can be similarly utilized if the inversion angle and the state of harmonic generation are known.

In Figure 1, when switches S ₁ and S ₂ are on and switches S ₂ and S ₃ are off, a normal voltage waveform is applied to the fluorescent lamp ballast 3, and when switches S ₁ and S ₄ are off and switches If S ₂ and S ₃ are on, an inverted voltage waveform is applied to the ballast 3 of the fluorescent lamp. This switch S ₁ , S ₄
The on/off control of the switches S ₂ and S ₃ is performed by the switch control unit 2 detecting the phase of the voltage waveform of the AC input voltage source as a synchronization signal and variably controlling the inversion angle.

Such a state will be explained with reference to FIG. Dimming state A is a normal state, and the average illuminance is maximum. Next, if the voltage is inverted at an angle of 24 degrees with respect to θ as shown in dimming state B, the fundamental wave becomes 0 as shown in FIG. Due to the nature of inductance, the impedance at both ends increases in proportion to the frequency, so as the number of high frequencies increases, the impedance of the chiyoke coil L increases and the tube current of the fluorescent lamp 4 decreases. In this case, the average illuminance is the lowest and can be about 40%. Dimming state C is a case where the voltage inversion angle θ is 24 degrees or less, and the average illuminance is between dimming states A and B. However, in either case, the power supplied to the filament of the fluorescent lamp 4 remains the same, so the thermoelectrons emitted from the filament do not change and the state does not become unstable, so the average illuminance can be dimmed to about 40%. . Note that the AC input voltage source does not need to be a commercial frequency as long as it is a sine wave, and the phase at which the voltage is inverted does not have to be centered around the maximum value of the sine wave. If the content is known, the light can be adjusted in the same way.

As explained above, according to the present invention, the dimming range of the fluorescent lamp can be greatly expanded, and there is no need to complicate the wiring of the fluorescent lamp and perform thinning of the lighting.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a dimmer device for a rapid starter type fluorescent lamp as an embodiment of the present invention;
FIG. 2 is a diagram illustrating the time chart for inverting a part of the sine wave waveform of the AC voltage and the average illuminance for the operation of each switch in the case of FIG.
A shows the commercial AC input voltage waveform, B shows the operating state of the switch, C shows the voltage waveform applied to the fluorescent lamp ballast, and D shows the average illuminance depending on the dimming state. Further, FIG. 3 is a diagram for explaining the principle, and FIG. 4 shows the amplitude ratio of the fundamental wave and high frequency in the case of FIG. 3, respectively. In the figure, 1 is a commercial AC input voltage source, 2 is a switch control unit, 3 is a rapid starter type ballast, 4 is a fluorescent lamp, S ₁ , S ₂ , S ₃ , S ₄ are switches, and e ₁ is a commercial AC input Voltage, e ₂ is the alternating voltage applied to the fluorescent lamp ballast,
T is a transformer, L is a chain coil portion, and θ is an angle representing 1/2 of the angle at which the voltage is reversed.

Claims (1)

[Scope of Claims] 1. A lighting device for a fluorescent lamp including a rapid starter ballast, which is connected between the input side of the rapid starter ballast and an AC input voltage source, and is configured to control the polarity of a part of the AC input voltage waveform. and a switch control unit that detects the phase of the waveform of the AC input voltage source as a synchronization signal and variably controls on/off periods of the plurality of switch elements. A dimmer device for fluorescent lights.