JPH0374091A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To prevent reduction in luminous efficiency by not connecting a smoothing capacitor to a rectifier at the time of power source input, but by connecting it to both ends of a first switching device through a discharge lamp as well as a current limiting inductance so as to be used as a smoothed power source. CONSTITUTION:A condenser C0 and a diode bridge DB are not connected with each other. In-rush current is thus never to run at the time of power source input. Since the choke current of L1 runs in the entire region of full-wave rectification wave shape, an input power factor can be heightened. Regarding the asymmetry of lamp current, at the bottom of the full-wave rectification wave shape, the condenser C0 becomes a power source, whereby the choke L1 is not actuated and exists, however, this condition continues only for a period at the bottom, and the longevity of the lamp is not so deteriorated. Reduction in luminous efficienty of the discharge lamp can thus be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a discharge lamp lighting device using a DC power source as a power source.

[Prior Art] Fig. 9 shows a conventional example, and this circuit configuration is a one-wheel inverter circuit, in which a high frequency voltage is generated by turning on and off a switching element Q, and the high frequency voltage is applied to a lamp La to power the lamp La. This is the circuit that lights up the . alternating current power supply ac
is full-wave rectified by a diode bridge DB, and its output is smoothed by a smoothing capacitor C0 to obtain a direct current. A DC power source is applied to the switching element Q via the choke L, and the switching element Q is controlled to be turned on and off by the control circuit 1. Further, a diode D as a switching element and a capacitor C5 are connected between the collector and emitter of the switching element Q1. The lamp La is connected to the power source via a choke L2 serving as a current limiting inductance.

Now, when switching element QI turns on, choke Ll
and the 10th Q? through a series circuit of lamp La and chiller Lt. A current flows through the switching element Q as shown in I(b). When switching element Q+ is turned off, current flows into capacitor C8 due to the energy stored in choke L+ and Lx. The charge stored in capacitor C1 is then discharged into the series circuit of choke upper 2 and lamps L and s. Ru. In this way, an oscillating circuit is formed by the series circuit of the capacitor C1, the upper choke 2, and the lamp La, and a high-frequency current flows through the lamp L@.

The input of the single-stone inverter is a DC voltage that has been completely smoothed by full-wave rectification of the AC power supply AC with a diode bridge DB. The reason for this is to increase the luminous efficiency of the lamp.If a waveform that has been simply full-wave rectified is used as input, the lamp voltage and current will become as shown in Figure 11, and the lamp current will not flow in the valleys, and the lamp will The arc is extinguished. Therefore, since this portion does not contribute to the light emission of the lamp, the luminous efficiency decreases.

On the other hand, when a smoothed voltage is used as an input, the lamp current flows continuously, so the lamp does not go out and the luminous efficiency improves.

[Problems to be Solved by the Invention] However, when complete smoothing is performed in this way, the following problems arise. First, when the power is turned on, the voltage charged in the smoothing capacitor C0 is zero, so inrush current flows into the power switch and diode bridge DB, causing an overcurrent to flow into the power switch and diode bridge DB. A large amount of stress is applied to the element. Second, since the input current flows only at the peak portion of the AC power supply, there is a problem that the input power factor is poor.

The present invention has been provided in view of the above-mentioned points, and provides a discharge lamp lighting device that suppresses the input inrush current when the power is turned on, improves the input power factor, and prevents the luminous efficiency from decreasing. It is something to do.

[Means for Solving the Problems] The present invention comprises a rectifier that performs full-wave rectification of an AC power supply, a closed circuit comprising a choke and a first switching element connected to the output side of the rectifier, and the first switching element. A series circuit connected to both ends of the switching element and consisting of a current limiting inductance, a discharge lamp, and a smoothing capacitor, a control circuit that controls on/off of the first switching element, and a second circuit that allows current to flow in the opposite direction to the first switching element. a switching element,
It is equipped with a choke, a current limiting inductance, a discharge lamp, and a capacitor that forms an oscillating circuit with a smoothing capacitor.

[Function] Therefore, when the power is turned on, a smoothing capacitor is not connected to the rectifier to prevent inrush current from flowing, and the smoothing capacitor connects a discharge lamp and a current limiting inductance to both ends of the first switching element. It is used as a smoothed power source to light a discharge lamp.

[Embodiment 1] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.One embodiment of the present invention is the Chilark L shown in the conventional example.

As shown in Figure 1, connect the capacitor C to the diode bridge DB, and connect the capacitor C to the diode bridge DBrl/I.
It is connected in series with the lamp L @ apart from the choke L, and the energy of the choke L is stored in the capacitor Co via the choke 2 and the lamp La, and the charging voltage of the capacitor Co is used as the power source to light the lamp La. It was there. That is, a series circuit of Chilark L and switching element Q1 is connected to the output end of diode bridge DB to form a closed circuit, and Chilark L2 as a current limiting inductance is connected between the collector and emitter of switching element Q+. A series circuit is connected between the lamp La and the capacitor C0. With this configuration, the input AC power supply A
Even in the troughs of C, the voltage of capacitor C. eliminates the lamp current's rest period and prevents the luminous efficiency from decreasing. In addition, the input diode bridge DB
Since the smoothing capacitor is not directly connected to the smoothing capacitor, there is no inrush current flowing into the smoothing capacitor when the power is turned on.
It also improves the input power factor.

Here, the role of the chiller L shown in the conventional circuit will be briefly explained. If there is no choke L1, when the switching element Q1 is turned on, a lamp current flows from the power supply through the lamp La and the upper choke 2, and the energy stored in the choke L2 when the switching element Q+ is turned off is stored in the capacitor C5. , is discharged from the capacitor CI to the lamp L@, and current flows in the opposite direction to the lamp La.

While the switching element Q is on, the choke L2
When the switching element Q1 is turned off, the energy accumulated in the lamp La is consumed and attenuated by the resistance of the lamp La.
Since the current is accumulated in the capacitor CI, the current flowing from the capacitor CI to the lamp La when it is off is the same as the current that flows from the lamp La when it is on.
The lamp current is smaller than the current flowing through a, and the lamp current has an asymmetrical waveform.

When used in this condition, the amount of electrons emitted from the picture electrode of the lamp La becomes unbalanced, and the thermionic emitting material (emitter) coated on one electrode is quickly consumed.1. This will shorten the life of the lamp La.

In order to improve the asymmetry of this lamp current, the choke L
There is. In other words, when the switching element Q is turned on,
By storing the energy stored in the choke L in the capacitor CI without going through the lamp La when it is off,
increasing the amount of energy stored in capacitor CI,
The current flowing through the lamp La from the capacitor C1 is increased to make the lamp current symmetrical in positive and negative directions.

In the circuit of the embodiment shown in FIG. 1, the choke L is connected to the diode bridge DB, and at the peak of the full waveform, when the switching element QI is turned on, the choke current flows from the diode bridge DB, and the lamp The current flows from capacitor C0 to lamp La and choke L! It flows.

When switching element Q is off, chokes L+ and L*
The capacitor C3 is charged by the energy of ・The charge of the capacitor C7 is the choke L! , charges the capacitor C0 via the lamp La, and increases the voltage of the capacitor C0. Since capacitor C0 has a sufficiently larger capacitance than capacitor C3, as shown in Fig. 2(e),
The voltage across capacitor C0 is smoothed.

Further, in the trough of the full waveform, the lamp current flows due to discharge from the capacitor C0. Therefore, as shown in Figure 2 (d), the lamp current has a waveform in which the valleys of the full-wave rectified waveform are filled in, and since there is no rest period of the lamp current, the lamp current has a waveform that is similar to that of a simple full-wave rectified waveform. La has high luminous efficiency.

In the circuit shown in FIG. 1, since the capacitor C0 and the diode bridge DB are not connected, an inrush current does not flow when the power is turned on as in the conventional example, and the inrush current does not flow in the entire range of the full-wave rectified waveform. Since the choke current flows, the input power factor can be made high.

In addition, the asymmetry of the lamp current is caused by the capacitor C0 becoming the voltage source in the troughs of the full-wave rectified waveform, so the choke L does not operate and exists only during the troughs, so the lamp life is particularly affected. It doesn't get worse.

Figure 3 shows a circuit similar to the previous embodiment, in which the switching element Q is also used as the switching element of the step-up flipper, and when the switching element Q is turned on, current flows through the choke L, and energy is generated. This circuit stores and charges the smoothing capacitor C when the switching element Q+ is off, and has the one-stone inverter circuit shown in the conventional example connected to both ends of the capacitor C0.

Although this circuit has one more choke than the present invention due to the boost flicker and the input power factor is improved,
This is a circuit with a different concept in that the inrush current when the power is turned on flows through the choke L5 and the diode D, and the inrush current cannot be improved.

[Example 21] Figure 4 shows Example 2, in which a diode D- is connected between the smoothing capacitor C0 and the output end of the diode bridge DB, and the output end voltage of the diode bridge DB is as shown in Figure 5 ( As shown in a), the waveform has a buried valley. Therefore, as shown in Fig. 5(b), the input current 1s has a waveform in which only the peaks of the output of the diode bridge DB flow, but the period in which it flows is wider than when it is completely smooth, and the input power factor becomes a high power factor. Become. In addition, this circuit has no input inrush current, and is different from the circuit in Figure 1 in that the lamp current does not become asymmetrical because a choke current flows from the smoothing capacitor C0 even at the input valley. There is a difference.

[Embodiment 3] Embodiment 3 is shown in FIG. 6. In this embodiment, the connection point of the choke top 1 is moved to the connection point of the choke top 1 and the lamp La, and the choke 2 is connected to the lamp current. This is a circuit configuration that flows a choke current of , and the effect is that the first
Same as in the figure.

Further, the connection point of the tick L may be made on the non-power side of the filament of the lamp La.

The capacitor C2 acts as a power source to flow a current in the opposite direction to the lamp La when the switching element Q1 is turned off, and the connection point may be the one shown in FIG. 7. In this case, when the switching element QI is turned off, The energy of choke Ll is choked → capacitor C1 →
Capacitor Co → Diode bridge DB → AC power supply A
It is accumulated through route C. The diode D1 connected in parallel with the switching element Q
This is to provide a current path so that the current flows in the opposite direction to , and other configurations may be used.

[Embodiment 4] Figure 8 shows Embodiment 4, in which the smoothing capacitor C0 is
In order to charge the inverter, connect the charging resistor R1 at the position shown in the figure or across the lamp La, and start the inverter after the voltage of the capacitor C becomes high.
It can be started from a stable state.

[Effects of the Invention] As described above, the present invention includes a rectifier that performs full-wave rectification of an AC power source, a closed circuit consisting of a choke and a first switching element connected to the output side of the rectifier, and the first switching element described above. A series circuit connected to both ends of the switching element and consisting of a current limiting inductance, a discharge lamp, and a smoothing capacitor, a control circuit that controls on/off of the first switching element, and a second circuit that allows current to flow in the opposite direction to the first switching element. The device is equipped with a switching element, a choke, a current limiting inductance, a discharge lamp, and a smoothing capacitor to form an oscillating circuit.When the power is turned on, the smoothing capacitor is not connected to the rectifier, so there is no inrush. The current can be prevented from flowing, and the smoothing capacitor is connected to both ends of the first switching element through the discharge lamp and current limiting inductance, and is used as a smoothed power source to light the discharge lamp. Yes, it is possible to avoid inrush current when the power is turned on, the input power factor can be made high, and there is no rest period in the lamp current, so it has the effect of not reducing the luminous efficiency of the discharge lamp. It is.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is an operation waveform diagram of the same as above, and Fig. 3 is a circuit diagram of an embodiment of the present invention. I is a circuit diagram with a different idea from the present invention,
Fig. 4 is a circuit diagram of Embodiment 2 of the present invention, Fig. 5 is an operation waveform diagram of the same as above, Fig. 6 is a circuit diagram of Embodiment 3 of the same as above, and Fig. 7 is a circuit diagram of Embodiment 3 of the same as above, and Fig. 7 shows a change in connection points of chokes, etc. of the same as above. 8 is a circuit diagram of the fourth embodiment, FIG. 9 is a circuit diagram of the conventional example, FIG. 10 is an operating waveform diagram of the same as the above, and FIG. 11 is an operating waveform diagram of the same as the above. . 1 is a control circuit, Q is a switching element, L@ is a lamp, L+, Lx are chokes, DB is a diode bridge,
AC is an alternating current power supply, D is a diode, C0 is a smoothing capacitor, and CI is a capacitor.

Claims (1)

[Claims] (1) A closed circuit consisting of a rectifier that full-wave rectifies an AC power supply, a choke and a first switching element connected to the output side of the rectifier, and a current-limiting inductance connected to both ends of the first switching element. , a series circuit consisting of a discharge lamp and a smoothing capacitor, a control circuit that controls on/off of the first switching element, a second switching element that allows current to flow in the opposite direction to that of the first switching element, a choke, and a current-limiting inductance. , a discharge lamp lighting device comprising a discharge lamp and a capacitor that constitutes an oscillating circuit with a smoothing capacitor.