JPS588116B2 - discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device, which achieves miniaturization and reduces power loss.

FIG. 1 shows a circuit example of a discharge dotting device that is the basis of the present invention.
A first closed circuit is formed by connecting the fluorescent lamp 4 to the fluorescent lamp 4, and a series circuit consisting of a switch element 6 and a capacitor 3 is connected between the non-power side terminals of both filaments 5, 5 of the fluorescent lamp 4. , AC power supply 1, inductance element 2, capacitor 3
, forming a second closed circuit including a switch element 6, the switch element 6 being closed at a constant phase in the first half of each half cycle of the alternating current power source 1, at least in the lighting state of the fluorescent lamp 4; ing.

In such a circuit, when the fluorescent lamp 4 has finished starting, when the switch element 6 closes as shown in FIG. A current Is flows through the inductance element 2, the capacitor 3, and the filaments 5, 5, and the filaments 5, 5 are sufficiently heated, and the inductance element 2 is caused by the strong vibration action of the capacitor 3 and the filaments 5, 5. Stores electrical energy.

Next, when the switch element 6 is closed at phase t2 during the half cycle, the voltage due to the electrical energy stored in the inductance element 2 is added to the power supply voltage V1, and a discharge occurs while the switch element 6 is in the closed state. The fluorescent lamp 4 is connected to both ends of the fluorescent lamp 4 which has been stopped, and the filaments 5, 5 are sufficiently heated by the current Is during its closing section.
The lamp is almost immediately re-ignited due to the high voltage, and the stored energy in the inductance element 2 and the power from the AC power supply 1 supply a lamp current I4 such as 2.

Then, when the switch element 6 is closed again at phase t1 in the next half cycle, both ends of the fluorescent lamp 4 are short-circuited and its discharge is stopped, and at the same time, the inductance 2 and the capacitor 3 are closed.
, filaments 5, 5 are formed, and the inductance element 2 accumulates energy due to strong vibration action and prepares for the arrival of phase t2.

This shows the input current I1 of the entire bobble circuit, and a continuous waveform with no rest periods can be obtained.

In this way, the energy storage effect of the inductance element 2 is effectively utilized to stably maintain normal lighting of the discharge lamp, so the power supply voltage may be low, and there is little difference from, for example, the lighting tube voltage, so there is a limit. The flow element can be made sufficiently smaller than conventional ones, making it possible to downsize the device and reduce power loss.

The present invention is characterized in that the discharge lamp lighting device maintains good characteristics almost constant even when the power supply voltage fluctuates.

In the circuit shown in FIG. 1, when the power supply voltage fluctuates, when the power supply voltage V1 becomes low, the LC when the switch element 6 is closed is
The boost effect due to series resonance becomes weaker, which not only reduces the light output, but also makes it impossible to re-ignite the discharge lamp, causing it to flicker or even go out.As the power supply voltage increases, the boost effect becomes stronger. Therefore, excessive power and voltage were supplied, the optical output increased too much, and the withstand voltage of the capacitor and switch element increased, which was uneconomical.

The present invention has been made in view of this point, and an object of the present invention is to move the closing phase t1 of the switch element forward or backward in accordance with fluctuations in the power supply voltage, thereby eliminating this inconvenience at once.

FIG. 3 shows an embodiment according to the present invention, in which an AC power supply 1
A discharge lamp 7 is connected to both ends of the inductance element 2 through an inductance element 2, and a triax 8 serving as a switch element is connected in parallel with the discharge lamp 7.
At the same time, a series circuit of a resistor 9 and a rectifier 10 is connected to both ends of the power supply 1, a constant voltage diode 11 is provided at the DC end of the rectifier 10, and a charging resistor 12 and an oscillation capacitor are connected to both ends of the rectifier 10. 13 series circuit UJT
A relaxation oscillation circuit 15 including 14 and the like is connected thereto, and a transistor 16 is provided in parallel with the charging resistor 12 to apply a voltage proportional to the power supply voltage between the pace emitters.

In such a device, the pulse voltage from the relaxation oscillator circuit 15 which is applied to the triator 8 and causes it to conduct, has a delayed phase as the time constant for charging the capacitor 13 is larger. Since the internal impedance increases or decreases in almost inverse proportion to the magnitude of V1, the charging time constant becomes smaller as the power supply voltage increases.As a result, when the power supply voltage is high, the closing phase of triax 8 is delayed, and when the power supply voltage is low, the charging time constant becomes smaller. is advancing the closing phase of triax 8.

In this way, the closing phase of the switch element is delayed or advanced in response to fluctuations in the power supply voltage, thereby maintaining constant characteristics.

This situation will be explained with reference to FIGS. 4 and 5.

The relationship between the closing phase t1 and the luminous flux L is as follows: the power supply voltage is 90%, 10
The curves A, B, and C are shown in FIG. 4 for 0% and 110%, and the relationship with the voltage V7 applied to the discharge lamp 7 is as follows for the power supply voltage 90%, 100%, and 110%. As shown in Figure 5, curves D, E, and F indicate that when trying to obtain the same luminous flux L or the same applied voltage V7 to the discharge lamp 7, The higher the power supply voltage V1 is, the more the closing phase t1 of the switch element is delayed.
You can see that it is best to proceed with step 1.

In this manner, the electrical characteristics can be maintained constant by automatically advancing or retracting the closing phase of the switch element in the circuit shown in FIG. 1, for example, in response to fluctuations in the power supply voltage.

[Brief explanation of the drawing]

FIG. 1 shows an example of a discharge lamp lighting circuit that is the basis of the present invention.
FIG. 2 is a waveform of each part thereof, FIG. 3 is a circuit diagram of an embodiment according to the present invention, and FIGS. 4 and 5 are characteristic diagrams for explaining the effects of the present invention.

Claims (1)

[Claims] 1. A discharge lamp is connected to the AC power supply terminal via a slow-phase current-limiting element including at least an inductance element, and a switch element is connected in parallel with the discharge lamp, and the switch element is connected to the power source when the discharge lamp is on. 1 for each half cycle of voltage
1. A discharge lamp lighting device configured to open and close by turning the discharge lamp, characterized in that the closing phase of a switch element is advanced or retracted depending on whether the power supply voltage is high or low.