JPH07192881A - High-frequency power source device, discharge lamp lighting device and luminaire - Google Patents

Abstract

PURPOSE:To use a simple circuit to stop an inverter circuit simultaneously with turn-off of a power source by using a comparing circuit to compare the reference voltage with the smoothing voltage of a pre-regulator, and generating the oscillation stop control signal, and supplying it. CONSTITUTION:A commercial alternating current power source 1 is rectified by a rectifying circuit, which is formed of a diode-bridge 2 connected through a power source switch SW1, and supplied to a pre-regulator 3 formed of a step-up chopper circuit, and regulated to a predetermined smooth direct current voltage. A series circuit of a resistor 13 and a constant voltage diode 14 is connected to a plus-side output terminal of the diode-bridge 2 to generate the reference voltage. A comparing circuit 7 compares the reference voltage with the smoothing voltage as the output of the regulator 3, and when the smoothing voltage is higher, the output of the circuit 17 becomes high-level. Then, since an oscillation stop circuit 18 is operated to send out the oscillation stop control signal to a driving circuit 12, oscillation of an inverter circuit 9 is stopped to protect switching elements 10, 11 of the circuit 9 from the external surge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency power supply device capable of stopping the output of an inverter at the same time as turning off the power supply and having an overvoltage protection function, a discharge lamp lighting device, and a lighting fixture using the discharge lamp lighting device.

[0002]

2. Description of the Related Art FIG. 4 shows a conventionally known discharge lamp lighting device. In this figure, the commercial AC power supply 30 is converted into a DC power supply by a rectifier circuit 32 connected via a power switch 31, and boosted by a pre-regulator 33 composed of a DC-DC converter. The output of the pre-regulator 33 is converted into a high frequency power source by the inverter circuit 35 and supplied to the load of a discharge lamp 36 such as a fluorescent lamp, and the discharge lamp 36 is lit at a high frequency.

[0003]

In the conventional discharge lamp lighting device configured as described above, the large-capacity smoothing capacitor 34 is connected to the output of the pre-regulator 33. Therefore, after the power switch 31 is turned off. The output voltage of the pre-regulator 33 does not immediately become zero, but drops slowly. Therefore, by controlling the electric power supplied to the discharge lamp 36 to be constant, the inverter circuit 35, which controls the brightness of the lamp to be constant, works even after the power switch 31 is turned off. The light does not go off immediately. In particular, in the dimming state, when the power is turned off during lighting, a phenomenon in which the lamp shines brightly for a moment (so-called off-pica) occurs. In order to prevent this phenomenon, conventionally, a power switch on / off detection circuit 37 is provided, and when the power switch 31 is turned off, an oscillation stop control signal is sent from the oscillation stop circuit 39 to the drive circuit of the inverter circuit 35. I needed to send it out.

In addition, when the output voltage of the pre-regulator 33 rises due to an external surge or the like, the inverter circuit 35
However, in order to prevent this problem, the overvoltage detection circuit 38 is connected to the output terminal of the preregulator 33 to prevent the inverter circuit 35 from oscillating when an overvoltage occurs. It was controlled so that it could be stopped. As described above, conventionally, it is necessary to provide two circuits for detecting the turning off of the power supply and detecting the overvoltage, which causes a problem that the circuit configuration becomes complicated.

The present invention has been proposed in order to solve the problems of the prior art as described above, and the inverter output can be stopped at the same time the power is turned off and the overvoltage protection function can be realized with a simple circuit configuration. An object of the present invention is to provide a high frequency power supply device, a discharge lamp lighting device, and a lighting fixture using the discharge lamp lighting device.

[0006]

In order to achieve this object, a high frequency power supply device according to the present invention has a rectifying circuit for converting a commercial AC power supply into a direct current and a smoothing capacitor on the output side. A pre-regulator that converts a voltage to a predetermined voltage, an inverter circuit that converts the output of the pre-regulator into a high-frequency power source, and supplies the load to a load,
A comparison circuit for comparing a reference voltage obtained from the output voltage of the rectifier circuit with a smooth voltage obtained from the smoothing capacitor of the pre-regulator, and an oscillation stop control signal generated by receiving a comparison output from the comparison circuit, And an oscillation stop circuit for supplying the circuit.

Further, the high frequency power supply device according to the present invention is configured to supply an oscillation stop control signal from the oscillation stop circuit to the preregulator to stop the operation of the preregulator.

Further, the discharge lamp lighting device according to the present invention has a rectifier circuit for converting a commercial AC power source into a direct current and a smoothing capacitor on the output side, and a preregulator for converting an output voltage of the rectifier circuit into a predetermined voltage. And compare the output of this pre-regulator to a high frequency power supply and the inverter circuit that supplies it to the discharge lamp and the reference voltage obtained from the output voltage of the rectifier circuit and the smooth voltage obtained from the smoothing capacitor of the pre-regulator. And a comparison circuit for receiving a comparison output from the comparison circuit to generate an oscillation stop control signal and supply it to the inverter circuit.

Further, the discharge lamp lighting device according to the present invention is configured to supply the oscillation stop control signal from the oscillation stop circuit to the pre-regulator to stop the operation of the pre-regulator.

Further, the lighting fixture according to the present invention has a structure in which a discharge lamp is mounted on the main body of the fixture and the discharge lamp is turned on by the discharge lamp lighting device.

[0011]

According to the above configuration, when the power is off, the smoothed voltage is higher than the reference voltage obtained from the output voltage of the rectifier circuit, so that the oscillation stop control signal is output from the oscillation stop circuit and the inverter circuit And the operation of the pre-regulator stops. Further, even when the smoothed voltage becomes higher than the reference voltage due to the influence of the external surge, the oscillation stop control signal is output from the oscillation stop circuit, and the operation of the inverter circuit and the pre-regulator can be stopped.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a discharge lamp lighting device according to the present invention. In this figure, commercial AC power supply 1
Is rectified by a rectifier circuit composed of a diode bridge 2 connected via a power switch SW1, supplied to a pre-regulator 3 composed of a step-up chopper circuit, and converted into a predetermined DC voltage. In the pre-regulator 3, one end of the inductor 4 is connected to the plus side output terminal of the diode bridge 2, and the other end of the inductor 4 and the switching element 5 are connected to the ground side. This switching element 5
Are switched by the drive circuit 6. Further, the inductor 4 is connected to the smoothing capacitor 8 via the diode 7.
It is connected to the. An inverter circuit 9 including, for example, a half-bridge inverter is connected to the output terminal of the pre-regulator 3, that is, both ends of the smoothing capacitor 8. Two switching elements 1 of this inverter circuit 9
0 and 11 are driven by the drive circuit 12. The load of a discharge lamp 21 such as a fluorescent lamp is connected to the output terminal of the inverter circuit 9 via a series circuit of a DC cut capacitor 19 and an inductor 20.

A series circuit of a resistor 13 and a constant voltage diode 14 is connected to the positive output terminal of the diode bridge 2, and the other end of the constant voltage diode 14 is grounded. The connection point between the resistor 13 and the constant voltage diode 14 is connected to the inverting input terminal of the comparison circuit 17. Also,
The voltage divider resistors 15 and 16 are connected to the output terminal of the smoothing capacitor 8.
Are connected in series, and the other end of the resistor 16 is grounded. The connection point of the voltage dividing resistors 15 and 16 is the comparison circuit 17
Connected to the non-inverting input terminal of. The output terminal of the comparison circuit 17 is connected to the oscillation stop circuit 18, and the oscillation stop circuit 18 is connected to the drive circuit 12 of the inverter circuit 9 and the drive circuit 6 of the pre-regulator.

In the discharge lamp lighting device having such a configuration, the reference voltage is generated from the output voltage of the diode bridge 2 by the resistor 13 and the constant voltage diode 14, and the reference voltage is supplied to the inverting input terminal of the comparison circuit 17 and divided. The smoothing voltage is detected by the piezoresistors 15 and 16, and the comparison circuit 17
Is supplied to the non-inverting input terminal of. During the lighting of the discharge lamp 21, the reference voltage applied to the point A of the inverting input terminal is set to be higher than the smoothing voltage applied to the point B of the non-inverting input terminal. Therefore, while the lamp is lit, the output voltage of the comparison circuit 17 becomes low level and the oscillation stop circuit 1
8 does not work. On the other hand, when the power switch SW1 is turned off, the voltage at the point B at which the voltage of the smoothing capacitor 8 is detected becomes
Since the time constant is longer than that at point A, the comparison circuit 17
The voltage of the non-inverting input terminal of the voltage rises as compared with the voltage of the inverting input terminal, and the output of the comparison circuit 17 becomes high level.

As a result, the oscillation stop circuit 18 operates to send the oscillation stop control signal to the drive circuit 12, so that the inverter circuit 9 immediately stops the oscillation and the discharge lamp 21 is turned off at the same time when the power supply voltage is turned off. . Therefore, the so-called off-pica phenomenon does not occur. At this time, the oscillation stop circuit 18 also sends an oscillation stop control signal to the drive circuit 6 of the pre-regulator 3, so that the operation of the pre-regulator 3 is also stopped. Further, even when the smoothed voltage rises due to an external surge or the like, the voltage at the point B becomes higher than the voltage at the point A, the output of the comparison circuit 17 becomes high level, and the oscillation stop circuit 18 operates. As a result, the oscillation stop control signal is sent to the drive circuit 12 and the oscillation of the inverter circuit is stopped, so that the switching elements 10 and 11 of the inverter circuit 9 can be protected from an external surge. At this time, the operation of the pre-regulator 3 is also stopped by the oscillation stop control signal.

Next, the high frequency power supply device shown in FIG. 2 will be described. In this embodiment, the load of the high frequency power source output from the inverter circuit 9 is not the discharge lamp but another load 2
2 is connected. In this high-frequency power supply device, like the discharge lamp lighting device of FIG. 1, the operation of the inverter circuit 9 and the pre-regulator 3 can be stopped at the same time when the power switch SW1 is turned off, and the switching element 10 of the inverter circuit 9 is prevented from overvoltage due to an external surge. 11 and the switching element 5 of the pre-regulator 3 can be protected.

FIG. 3 shows a lighting fixture using the discharge lamp lighting device of FIG. In this figure, a discharge lamp 21 composed of a fluorescent lamp is attached to the instrument body 23, and the fluorescent lamp is attached to the instrument body 2
The discharge lamp lighting device U1 of FIG. In this luminaire, the oscillation of the inverter circuit 9 can be stopped at the same time when the power switch SW1 is turned off, so that no off-picker occurs. In addition, when an overvoltage occurs due to an external surge, the inverter circuit 9
Of the inverter circuit 9,
11 can be protected and the reliability of the lighting fixture can be improved.

[0018]

As described above, according to the present invention, the comparison circuit compares the reference voltage obtained from the output voltage of the rectifier circuit with the smoothing voltage of the smoothing capacitor of the pre-regulator, and the inverter outputs based on this comparison output. Since the circuit oscillation can be stopped, the operation of the inverter circuit can be stopped at the same time as the power switch is turned off, and the so-called off-pica phenomenon that the lamp in the dimming state lights up brightly for a moment when the power is turned off is prevented. it can. In addition, even if an overvoltage is input due to an external surge, etc., the operation of the inverter circuit and preregulator can be stopped at the same time when the overvoltage occurs, so the switching elements that make up the inverter circuit and the switching elements that make up the preregulator are protected from overvoltage. The reliability of the device can be improved. Further, in the present invention, since these two functions can be realized by a simple circuit, the number of parts can be reduced and the reliability can be improved.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing an embodiment of a high frequency power supply device according to the present invention.

FIG. 3 is a configuration diagram of a lighting fixture using the discharge lamp lighting device of FIG. 1.

FIG. 4 is a block diagram showing a conventional discharge lamp lighting device.

[Explanation of symbols]

 1 Commercial AC Power Supply 2 Diode Bridge 3 Pre-Regulator 5 Switching Element 6 Drive Circuit 8 Smoothing Capacitor 9 Inverter Circuit 10, 11 Switching Element 12 Drive Circuit 13 Resistor 14 Constant Voltage Diode 15, 16 Voltage Dividing Resistor 17 Comparison Circuit 18 Oscillation Stop Circuit 21 Discharge lamp 22 Load 23 Instrument body U1 Discharge lamp lighting device SW1 Power switch

Claims (5)

[Claims] 1. A rectifier circuit for converting a commercial AC power source into a direct current, a smoothing capacitor on the output side, a preregulator for converting an output voltage of the rectifier circuit into a predetermined voltage, and an output of the preregulator at a high frequency. Convert to power,
An inverter circuit that supplies the load, a comparison circuit that compares the reference voltage obtained from the output voltage of the rectifier circuit with a smoothed voltage obtained from the smoothing capacitor of the pre-regulator, and an oscillator that receives the comparison output from this comparison circuit. A high-frequency power supply device, comprising: an oscillation stop circuit that generates a stop control signal and supplies the stop control signal to the inverter circuit. 2. A rectifier circuit for converting a commercial AC power supply to a direct current, a smoothing capacitor on the output side, a pre-regulator for converting an output voltage of the rectifier circuit into a predetermined voltage, and an output of the pre-regulator at a high frequency. Convert to power,
An inverter circuit that supplies the discharge lamp, a comparison circuit that compares the reference voltage obtained from the output voltage of the rectifier circuit with the smoothed voltage obtained from the smoothing capacitor of the pre-regulator, and the comparison output from this comparison circuit. A discharge lamp lighting device, comprising: an oscillation stop circuit that generates an oscillation stop control signal and supplies the oscillation stop control signal to the inverter circuit. 3. The high frequency power supply device according to claim 1, wherein an oscillation stop control signal from the oscillation stop circuit is supplied to the preregulator to stop the operation of the preregulator. 4. The discharge lamp lighting device according to claim 2, wherein an oscillation stop control signal from the oscillation stop circuit is supplied to the pre-regulator to stop the operation of the pre-regulator. 5. The discharge lamp is attached to the instrument body, and
Alternatively, a lighting fixture is characterized in that the discharge lamp is turned on by the discharge lamp lighting device according to claim 4.