JPH06243980A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To make extinction hard to be caused by arranging a circuit to detect instantaneous power failure and an instantaneous voltage drop between AC electric power supply and a smoothing capacitor, and increasing an oscillation frequency of an inverter circuit more than a starting time LC resonance frequency when this detects the power failure and the voltage drop. CONSTITUTION:An instantaneous power failure detecting circuit 5 is arranged between output voltage of an electric power supply part 1 to supply AC electric power E and an inverter circuit 2 through a smoothing capacitor C0, and when instantaneous power failure is caused in the electric power supply E, a detecting signal is sent to the circuit 2, and an oscillation frequency from here is transferred to unlighted time from lighting time. In a circuit 5, full wave rectification is carried out on AC voltage AC whose pressure is divided by resistors R1 and R2 by a diode bridge DB1, and a signal from here is differentiated by a differentiating circuit composed of resistors R3 and R4 and a capacitor C1, and only when the instantaneous power failure and an instantaneous voltage drop are caused, a trigger is applied to a monostable multivibrator MM1. In this way, a frequency of the circuit 2 is put in a lagging mode, and breakdown of a switching element of the circuit 2 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a high voltage L for starting.
The present invention relates to a discharge lamp lighting device generated by a C series resonance circuit.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional discharge lamp lighting device of this type.
It is a block diagram. AC as shown in FIG.
Power source E, power source unit 1 for converting alternating current to direct current, smoothing capacitor
Sensor C ₀, An inverter circuit 2 and a load circuit 3,
A lighting determination circuit 4 for detecting lighting of the lamp is provided.

When the lighting discrimination circuit 4 judges that the lamp is lit, it controls the inverter circuit 2 so that the inverter circuit 2 oscillates at the lighting frequency f ₁ , and when it is judged that the lamp is not lit, the igniter operation frequency f _{Works with} ' ₀ '. Here, FIG. 6 shows a specific circuit diagram of the load circuit 3, which includes an inductor L, a capacitor C, and an equivalent resistance R of the lamp.

By the way, since no current flows in the discharge lamp (lamp) when it is not lit, the load circuit 3 is not lit.
Can be represented as in FIG. FIG. 8 shows a specific circuit diagram of the lighting determination circuit 4, in which the voltage across the detection resistor R _{1 for} the lamp current is the diode D ₁ , the capacitor C ₁ , and the resistor R _2.
The comparator CP ₁ compares the detection signal obtained through the smoothing rectification circuit composed of the reference voltage V ₁ with the reference voltage V _1, and when the lamp is turned on and the detection signal exceeds the reference voltage V ₁ , the comparator CP ₁ The output goes high.

Here, FIG. 9 shows the steady state of the lamp,
FIG. 10 shows the starting time of the lamp. That is, FIG.
10 (a) shows the steady state of the inverter circuit 3 and the output voltage (ab) during igniter operation, and FIGS. 9 (b) and 10 (b) show the lamp output during steady state and igniter operation. The voltage applied to both ends is shown (c- in FIG. 6).
d, see c'-d 'in FIG. 7).

[0006]

In the conventional example, when the lamp goes out due to an instantaneous power failure or the like, a delay occurs due to the presence of the smoothing capacitor C ₀ , and the lighting determination circuit 4 has a time lag. During that time, the inverter circuit 2 enters the phase advance mode, and an excessive current flows through the switching element forming the inverter circuit 2, resulting in destruction of the switching element.

On the contrary, if the sensitivity of the lighting discrimination circuit 4 is increased in order to reduce the time lag, there is a problem that the operation becomes unstable due to a malfunction due to noise or the like. The present invention has been made in view of the above points, and provides a discharge lamp lighting device intended for safe operation even when the power supply environment deteriorates due to an instantaneous power failure or the like.

[0008]

The present invention includes an AC power supply,
A power supply unit that converts this AC power supply to DC, a smoothing capacitor that smoothes the output from this power supply unit, an inverter circuit that oscillates at a predetermined frequency using the voltage of this smoothing capacitor as a power supply, and the load of this inverter circuit. In a discharge lamp lighting device that is equipped with a load circuit that becomes an LC resonance circuit when the lamp is not lit, and generates high voltage by series resonance at a resonance frequency higher than the lighting frequency when the lamp is started, an instantaneous power failure or momentary If a momentary power failure or instantaneous voltage drop is detected by the instantaneous power failure detection circuit, an instantaneous power failure detection circuit that detects the voltage drop of the inverter is installed between the AC power supply and the smoothing capacitor. The LC resonance frequency is increased.

[0009]

According to the present invention, it is possible to prevent the switching element of the inverter circuit from being broken even in the case of momentary power failure or momentary voltage drop. Moreover, since the lighting frequency is increased at the time of momentary power failure and the like, the electric energy consumed during this period is reduced, so that disappearance due to momentary power failure is more difficult to occur.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of a discharge lamp lighting device of the present invention. The basic configuration is the same as that of the conventional example shown in FIG. 5, and the present invention is characterized in that an instantaneous power failure detection circuit 5 is provided.
The description of the same parts as in the conventional example will be omitted, and the gist of the present invention will be described in detail.

That is, the instantaneous power failure detection circuit 5 is provided between the AC power supply E and the smoothing capacitor C _{0. When} the AC power supply E experiences a momentary power failure, a detection signal is sent to the inverter circuit 2. Therefore, the oscillating frequency of the inverter circuit 2 is changed from f ₁ when lighting to f ₀ ′ when not lighting. FIG. 2 shows a concrete circuit diagram of the instantaneous power failure detection circuit 5, in which the AC voltage AC divided by the resistors R ₁ and R ₂ is used.
Is full-wave rectified by the diode bridge DB ₁ . This signal is applied to resistors R ₃ , R _{4 and} capacitor C ₁
Only when the AC power supply E is differentiated by a differentiating circuit configured to generate an instantaneous power failure or an instantaneous voltage drop, a monostable multivibrator MM ₁ (for example, NEC
The µPD74HC123AC manufactured by the company is triggered.

As a result, the output of the instantaneous power failure detection circuit 5 becomes H level for a certain period of time after the AC power source E becomes abnormal. This H level signal is input to the inverter circuit 2, and the oscillation frequency of the inverter circuit 2 is f at the time of lighting.
_{The operation} shifts from ₁ to f ₀ 'when the frequency is higher than f ₁ and is not lit. Further, the frequency may be set higher than f ₀ ′.

As a result, the oscillating frequency of the inverter circuit 2 is in the delay mode, and the destruction of the switching element of the inverter circuit 2 is prevented. (Embodiment 2) Embodiment 2 is shown in FIG. The basic configuration is the same as that of the previous embodiment shown in FIG. FIG. 3 shows a specific circuit diagram of the power supply unit 1 and the instantaneous power failure detection circuit 5.
In the case where only full-wave rectification is performed by the diode bridge DB ₁ , the diode D ₁ is provided so that the signal source for the instantaneous power failure detection is the diode bridge DB ₁ and the diode D ₁
You can get more in between.

Since the operation of the instantaneous power failure detection circuit 5 is the same as that of the previous embodiment, its explanation is omitted. Further, the instantaneous power failure detection circuit 5 in the present embodiment is simply provided with a voltage follower by the operational amplifier OP ₁ , and other configurations are the same as those in the previous embodiment. (Third Embodiment) FIG. 4 shows a third embodiment. Also in the present embodiment, the basic configuration is the same as in the case of FIG. FIG. 4 shows the power supply unit 1.
And a concrete circuit diagram of the instantaneous power failure detection circuit 5,
The power supply unit 1 includes a diode bridge DB ₁ , an inductor L ₁ , a diode D ₁ , a smoothing capacitor C ₀ , a switching element Q ₁ and a control circuit CC for controlling a chopper circuit.
In the case of the chopper circuit consisting of, the signal source for the instantaneous power failure detection can be used together with the feedforward detection signal reaching the control circuit CC.

Since the configuration and operation of the instantaneous power failure detection circuit 5 are the same as those of the previous embodiment, the description thereof will be omitted.

[0016]

According to the present invention, an AC power supply, a power supply section for converting the AC power supply into a DC power supply, a smoothing capacitor for smoothing an output from the power supply section, and a voltage of the smoothing capacitor as a power supply. Equipped with an inverter circuit that oscillates at a predetermined frequency and a load circuit that becomes a load of this inverter circuit and that becomes an LC resonance circuit when the lamp is not lit. In a discharge lamp lighting device that generates high voltage due to the Is detected, the oscillation frequency of the inverter circuit is set to L
Since the frequency is higher than the C resonance frequency, destruction of the switching element of the inverter circuit can be prevented even in the case of momentary power failure or momentary voltage drop. Moreover, in order to increase the lighting frequency in the event of a momentary power failure,
Since the electric energy consumed during this period is reduced, there is an effect that fading due to an instantaneous power failure or the like becomes less likely to occur.

[Brief description of drawings]

FIG. 1 is an overall block diagram of a discharge lamp lighting device according to an embodiment of the present invention.

FIG. 2 is a specific circuit diagram of the above instantaneous power failure detection circuit.

FIG. 3 is a specific circuit diagram of a power supply unit and an instantaneous power failure detection circuit according to the second embodiment.

FIG. 4 is a specific circuit diagram of a power supply unit and an instantaneous power failure detection circuit according to the third embodiment.

FIG. 5 is a block diagram of a conventional discharge lamp lighting device.

FIG. 6 is an equivalent circuit diagram of the above load circuit.

FIG. 7 is an equivalent circuit diagram of a load circuit when the above lamp is not lit.

FIG. 8 is a specific circuit diagram of the above lighting determination circuit.

FIG. 9 is an operation waveform diagram in the above steady state.

FIG. 10 is an operation waveform diagram at the time of starting the same as above.

[Explanation of symbols]

1 Power Supply Section 2 Inverter Circuit 3 Load Circuit 4 Lighting Discrimination Circuit 5 Instantaneous Power Failure Detection Circuit E AC Power Supply C ₀ Smoothing Capacitor

Claims (1)

[Claims] 1. An AC power supply, a power supply section for converting the AC power supply into DC, a smoothing capacitor for smoothing an output from the power supply section, and a voltage of the smoothing capacitor as a power supply for oscillation at a predetermined frequency. An inverter circuit and a load circuit that serves as a load of the inverter circuit and serves as an LC resonance circuit when the lamp is not lit are provided, and when the lamp is started, a high voltage is generated by series resonance at a resonance frequency higher than the frequency when the lamp is lit. In the electric lighting device, if an instantaneous power failure detection circuit that detects an instantaneous power failure or an instantaneous voltage drop is provided between the AC power supply and the smoothing capacitor, and the instantaneous power failure or instantaneous voltage drop is detected by the instantaneous power failure detection circuit, The discharge lamp lighting device is characterized in that the oscillation frequency of the inverter circuit is made higher than the LC resonance frequency at the time of starting.