JP2000277283A - Discharge lamp lighting device and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device operating without the use of element with high breakdown voltage. SOLUTION: A diode D3 is turned on, while a transistor Q1 is on to cause a drop of the cathode potential of a trigger stop diode D4, and electric charges on a capacitor C5 are discharged. Because the time constant of a resistance R1 and capacitor C5 at which the capacitor C5 is charged to cause a trigger element Z1 to be turned on, is set in a lag from the switching time of the transistor Q1, the capacitor C5 is kept in a condition of not being charged, as long as the transistor Q1 is in switching operations. When an inverter circuit 15 is in operation with the transistor Q1 in switching motion, the capacitor C5 is not charged, so that there is no need to equip the trigger stop diode D4 with a high breakdown voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for lighting a discharge lamp and a lighting device.

[0002]

2. Description of the Related Art Conventionally, as a discharge lamp lighting device of this type, an inverter circuit for lighting a discharge lamp is connected to a DC power supply. That is, a parallel resonance circuit and a transistor are connected in series between the DC power supplies, a series circuit of a resistor and a capacitor is connected between the DC power supplies, and a connection point of the resistor and the capacitor is connected via a diode to the parallel resonance circuit and the transistor. It is connected to a connection point of the transistor and is connected to a base of the transistor via a trigger element.

When the capacitor is charged to a predetermined voltage value or more, the trigger element is turned on to turn on the transistor to start the inverter circuit. While the transistor is operating, the charge of the capacitor is discharged via the diode. are doing.

In this way, the inverter circuit is operated and converted into a high frequency by the inverter circuit, so that the discharge lamp is lit at a high frequency.

[0005]

However, as described above, in the configuration in which the charge of the capacitor is discharged by the diode, the voltage of the parallel resonance circuit is applied to the diode, so that the diode has a high withstand voltage. There is a problem that an element must be used.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a discharge lamp lighting device and an illuminating device which operate without using a device having a high withstand voltage.

[0007]

According to a first aspect of the present invention, there is provided a discharge lamp lighting device comprising: a first capacitor connected to an AC power supply;
A rectifier connected to the first capacitor; a second capacitor connected to the rectifier; a resonance inductance circuit having a primary winding of a transformer connected to a discharge lamp on a secondary winding side; An inverter circuit having a resonance capacitor that resonates with the resonance inductance circuit and a switching element connected to the resonance inductance circuit and generating a high-frequency voltage by a switching operation; an inductance element, connected in series to the inductance element; A charging capacitor that is charged at a voltage lower than the maximum instantaneous voltage value of the output of the rectifier, a return diode connected in series with the inductance element and the charging capacitor to return the current of the switching element, and an inductance and a charge. Parallel to capacitor A partial smoothing circuit having a feedback diode connected to the second capacitor and connected in parallel to the second capacitor and connected to the inverter circuit; a trigger circuit for generating a starting voltage when the operation of the switching element is started; After the operation of the element, the trigger of the trigger circuit is stopped. The trigger circuit is provided with a trigger stop diode connected between the trigger circuit and the connection point of the return diode and the feedback diode. When the operation of the element is started, while the switching element is on, the trigger circuit does not generate a start voltage by the trigger stop diode, and only the voltage at both ends of the partial smoothing circuit is applied to the trigger stop diode, No high voltage is applied to the trigger stop diode.

[0008] A lighting device according to a second aspect of the present invention includes an apparatus main body to which a discharge lamp is mounted, and a discharge lamp lighting device according to the first aspect of the present invention for lighting the discharge lamp.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An illumination device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a perspective view showing the external appearance of the lighting device. As shown in FIG. 2, the lighting device 1 has a reflecting surface 3 formed on the lower surface of a fixture body 2 and lamps at both ends of the reflecting surface 3. Sockets 4 and 4 are formed, a fluorescent lamp FL as a discharge lamp is mounted between the lamp sockets 4 and 4, and a discharge lamp lighting device 5 shown in FIG. 1 is mounted inside.

FIG. 1 is a circuit diagram showing a discharge lamp lighting device. As shown in FIG. 1, a discharge lamp lighting device 5 has a first capacitor C1 having a relatively large capacity connected to a commercial AC power supply e. The input terminal of the full-wave rectifier circuit 11 as rectifying means is connected to the first capacitor C1, and the output terminal of the full-wave rectifier circuit 11 is connected in series with a second capacitor C2 having a smaller capacity than the first capacitor C1. Connect the circuit and this second capacitor
A partial smoothing circuit 12 for valley filling is connected in parallel with C2.
Further, the partial smoothing circuit 12 is configured such that a charging capacitor C3, a series circuit of an inductor L1 as an inductance element and a return diode D1 are connected to an output terminal of the full-wave rectifier circuit 11, and a series circuit of the charging capacitor C3 and the inductor L1 is connected. , A feedback diode D2 is connected in anti-parallel, a diode D3 is connected to a connection point between the charging capacitor C3 and the return diode D1, and an inverter circuit 15 is connected to the partial smoothing circuit 12.

A parallel resonance circuit 16 is connected to the inverter circuit 15. This parallel resonance circuit 16
A resonance inductance circuit 17 composed of a series circuit of a primary winding Tr1a of an inverter transformer Tr1 functioning as an inductor and an inductor L2;
And a resonance capacitor C4 that resonates. Also,
A transistor Q1 as a switching element is connected to the parallel resonance circuit 16 in series. In the inverter transformer Tr1, the primary winding Tr1a and the secondary winding Tr1b are formed by tight coupling with a coupling coefficient of about 0.8 to 1.0.

A trigger circuit 18 for starting is connected in parallel with the second capacitor C2. This trigger circuit 18 is a series circuit of a resistor R1 and a capacitor C5 in parallel with the second capacitor C2. The connection point of the resistor R1 and the capacitor C5 is connected to the base of the transistor Q1 via the trigger element Z1, and the anode of the feedback diode D2, the anode of the diode D3, and the return current via the trigger stop diode D4. It is connected to the cathode of diode D1.

On the other hand, the secondary winding of the inverter transformer Tr1
A load circuit 19 is connected to Tr1b.
The fluorescent lamp FL is connected via the primary winding CT1a of the feedback current transformer CT1 and the DC cut capacitor C6. One end of the filaments FL1 and FL2 of the fluorescent lamp FL is connected to the other end of the filaments FL1 and FL2. A starting capacitor C7 is connected between them. The control circuit 20 for the transistor Q1 is connected to the secondary winding CT1b of the current transformer CT1, and the control circuit 20 connects the secondary winding CT1b of the current transformer CT1 to the transistor Q1 via the capacitor C8.
And a series circuit of a diode D5 and a resistor R2.

Next, the operation of the above embodiment will be described.

First, the capacitor C5 is charged via the resistor R1, and when the voltage of the capacitor C5 exceeds a predetermined value and the trigger element Z1 reaches the break voltage, it turns on and supplies a base current from the capacitor C5 to the transistor Q1. Turn on. As described above, when the transistor Q1 is turned on, the resonance capacitor C4, the inductor L2 of the resonance inductance circuit 17, and the primary winding Tr1a of the inverter transformer Tr1 are turned on.
Current flows through the secondary winding Tr1b of the inverter transformer Tr1.
, A voltage is induced. Then, the resonance capacitor C4, the inductor L2, and the primary winding Tr of the inverter transformer Tr1.
The parallel winding of 1a and the current from the current transformer CT1 are supplied to the base of the transistor Q1 so that the secondary winding
A high-frequency voltage is induced in Tr1b, and the fluorescent lamp FL is turned on at a high frequency.

That is, the secondary winding CT of the current transformer CT1
When a voltage is induced in 1b, the capacitor C8 is charged, and the transistor Q1 maintains the ON state. Then, when the current transformer CT1 is magnetically saturated, the voltage positively fed back to the current transformer CT1 becomes 0, and the base of the transistor Q1
The accumulated charge between the emitters is rapidly released and the transistor
Q1 turns off. In addition, the resonance current of the parallel resonance circuit 16 causes a resonance current to flow through the inverter transformer Tr1, and the secondary winding
Although a voltage is induced in Tr1b, the transistor Q1 remains off due to the current in the direction of turning off the transistor Q1. Thereafter, when the direction of the resonance current of the parallel resonance circuit 16 is reversed and a voltage is induced in the primary winding CT1a of the current transformer CT1 to turn on the transistor Q1, the transistor Q1 turns on. This operation is repeated to turn on the fluorescent lamp FL at high frequency.

Further, while the transistor Q1 is on, the potential of the cathode of the trigger stop diode D4 is reduced by turning on the diode D3, and the electric charge of the capacitor C5 is discharged. In other words, since the time constant of the resistor R1 and the capacitor C5 at which the capacitor C5 is charged and the trigger element Z1 is turned on is set later than the switching time of the transistor Q1, the capacitor C5 is not charged while the transistor Q1 is performing the switching operation. Keep.

As described above, when the inverter circuit 15 in which the transistor Q1 is switching operates, the capacitor C5
And the potential of the cathode of the trigger stop diode D4 corresponds to the voltage of the partial smoothing circuit 12, so that a low withstand voltage element can be used, and the cost of parts can be reduced. Since the creepage distance can be reduced, the degree of freedom of the pattern increases, and the miniaturization of the device becomes easy.

When the transistor Q1 is turned on, a current flows through the primary winding Tr1a of the inverter transformer Tr1, and a current flows through the charging capacitor C3, the inductor L2 and the return diode D1, thereby charging the charging capacitor C3. . And a full-wave rectifier circuit is added to the charging capacitor C3.
DC voltage lower than the peak value of the pulsating voltage from 11 can be stored. When the direction of the current is reversed, the current of the charging capacitor C3 is bypassed to the feedback diode D2, and the charging capacitor C3 is not charged by the current in this direction.

Here, a description will be given of a section in which the pulsating voltage of the full-wave rectifier circuit 11 is higher than the charging voltage of the charging capacitor C3 and a section in which the pulsating voltage is lower than the charging voltage.

First, when the transistor Q1 of the inverter circuit 15 is turned on at an arbitrary time in a section where the pulsating voltage of the full-wave rectifier circuit 11 is higher than the charging voltage of the charging capacitor C3, the primary winding Tr1a of the inverter transformer Tr1 is turned on. Most of the current is supplied from the first capacitor C1 and partly from the second capacitor C2, and also charges the charging capacitor C3. Note that, in a section where the voltage value of the full-wave rectifier circuit 11 is high, the discharge is not performed from the charging capacitor C3 to the inverter circuit 15 side. And the first capacitor
The combined capacitance of C1 and second capacitor C2 is sufficient to provide the energy required by inverter circuit 15. In accordance with the current supply from the first capacitor C1 and the second capacitor C2, energy flows from the commercial AC power supply e side as an input current. Then, an operation is performed so as to accompany the switching operation of the transistor Q1 in response to the change of the pulsating voltage, and the small and equal amplitude of the high frequency of the inverter operation of the inverter circuit 15 along the AC voltage sine wave value becomes full wave. The voltage value of the rectifier circuit 11 is superimposed on all high sections.

That is, in the section where the voltage value of the full-wave rectifier circuit 1 is high, the first capacitor C1 and the second capacitor C2
Is a value that satisfies the energy given by the supplied pulsating voltage with respect to the energy required by the inverter circuit 15.

For this reason, both the first capacitor C1 and the second capacitor C2 have a small ripple component, a small amount of heat generation, and can improve the operation reliability.

Next, in a section where the voltage value of the full-wave rectifier circuit 11 is low, when the pulsating sine wave voltage of the full-wave rectifier circuit 11 starts to decrease with respect to the charging voltage of the charging capacitor C3, the transistor Q1 is turned on. When turned on, the current to the primary winding Tr1a of the inverter transformer Tr1 is first supplied from the second capacitor C2, and the inductor L1, the charging capacitor
A current flows through the path of C3, the freewheeling diode D1 and the transistor Q1, and the charging capacitor C3 is discharged.
The DC voltage becomes lower than the peak value of the pulsating voltage from step 11.
The capacity of the second capacitor C2 is determined by the inverter circuit 15
Is insufficient to provide the required energy, the voltage of the second capacitor C2 decreases as the current flowing through the primary winding Tr1a increases after the transistor Q1 is turned on.
And the voltage of the second capacitor C2 is the first capacitor
The first capacitor C1 supplies the energy to the inverter circuit 15 that is insufficient in the second capacitor C2 from the time when the voltage has dropped to the voltage of C1.

Then, the voltage is supplied until the transistor Q1 is turned off. However, the decrease in the voltage of the second capacitor C2 after the supply of energy from the first capacitor C1 is started is reduced. The first capacitor C1 is connected to the inverter circuit.
Energy supply to 15 causes an amount of energy corresponding to this to flow as input current from the commercial AC power supply e side.

On the other hand, the charging voltage of the charging capacitor C3 is determined by the inductor L2 and the primary winding Tr of the inverter transformer Tr1.
The release of energy is delayed by the transient impedance of 1a,
The energy is released immediately before the transistor Q1 is turned off. Then, when the transistor Q1 is turned off, the charging voltage of the charging capacitor C3 becomes a voltage supply source to the series circuit of the inductor L2, the primary winding Tr1a of the inverter transformer Tr1, the full-wave rectifier circuit 11, and the first capacitor C1. Here, since the series circuit of the inductor L2 and the primary winding Tr1a of the inverter transformer Tr1 and the second capacitor C2 are set so as to obtain oscillatory resonance, the second capacitor C2 has a sinusoidal waveform. Charged. This charging is increased in the inverter circuit 15 to a voltage at which the energy supply does not become insufficient when the transistor Q1 is turned on next time. When the transistor Q1 is turned off, resonance occurs in the resonance capacitor C4 and the series circuit of the inductor L2 and the primary winding Tr1a of the inverter transformer Tr1. And this resonance current is
D1, diode D3, primary winding of inverter transformer Tr1
Tr1a, second capacitor C2, and capacitor for resonance
The current flows through the path of C4, and the second capacitor C2 is charged to generate an oscillating voltage. At this time, the voltage across the second capacitor C2 has almost the same voltage value as the DC voltage at both the highest instantaneous voltage portion and the lowest instantaneous voltage portion of the commercial AC power supply e.

Then, as the voltage of the first capacitor C1 decreases with respect to the charging voltage of the charging capacitor C3, the voltage of the second capacitor C2 decreases.
Of the capacitor C2 increases. Further, although the input current decreases, the current flows continuously.

As described above, since the input current from the commercial AC power supply e continuously flows, it is possible to prevent a harmonic component from intervening in the input current.

It should be noted that the same effect can be obtained even if the inverter transformer Tr1 is replaced by a leakage-coupled transformer having a coupling coefficient of about 0.5 to 0.8 instead of the tightly-coupled transformer, and without the inductor L2. it can.

[0031]

According to the discharge lamp lighting device of the present invention, the trigger circuit generates the start voltage to start the operation of the switching element. While the switching element is on, the trigger stop diode is used for the trigger circuit. Does not generate a start voltage, only the voltage at both ends of the partial smoothing circuit is applied to the trigger stop diode, and a high voltage is not applied to the trigger stop diode, so that components with a high withstand voltage can be reduced.

According to the lighting device of the second aspect, since the lighting apparatus of the first aspect of the present invention is provided with the apparatus body to which the discharge lamp is mounted and the discharge lamp lighting device of the first aspect for lighting the discharge lamp.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a discharge lamp lighting device of the present invention.

FIG. 2 is a perspective view showing an appearance of the lighting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Illumination device 2 Appliance body 5 Discharge lamp lighting device 11 Full-wave rectification circuit as rectification means 12 Partial smoothing circuit 15 Inverter circuit 17 Resonance inductance circuit 18 Trigger circuit C1 First capacitor C2 Second capacitor C3 Charging capacitor C4 Resonant capacitor D1 Reflux diode D2 Feedback diode D4 Trigger stop diode e Commercial AC power supply FL Fluorescent lamp as discharge lamp L1 Inductor as inductance element Q1 Transistor Tr1 as switching element Inverter transformer Tr1a having an inductor function Primary winding Tr1b Secondary winding

Claims (2)

[Claims] A first capacitor connected to an AC power supply; a rectifier connected to the first capacitor; a second capacitor connected to the rectifier; and discharging to a secondary winding side. It has a resonance inductance circuit having a primary winding of a transformer to which a lamp is connected, a resonance capacitor that resonates with the resonance inductance circuit, and a switching element that is connected to the resonance inductance circuit and generates a high-frequency voltage by switching operation. An inductance element, an inductance element, a charging capacitor connected in series with the inductance element and charged with a voltage lower than the maximum instantaneous voltage value of the output of the rectifier, and a serial connection with the inductance element and the charging capacitor. A free-wheeling diode connected to return the current of the switching element, and A partial smoothing circuit having a feedback diode connected in antiparallel to the inductance and the charging capacitor, connected in parallel to the second capacitor, and connected to the inverter circuit; operation of the switching element A trigger circuit for generating a start voltage at the start; and a trigger stop diode connected between the trigger circuit and a connection point between the freewheel diode and the feedback diode for stopping a trigger of the trigger circuit after the operation of the switching element. Discharge lamp lighting device characterized by the above-mentioned. 2. An illumination device comprising: a fixture main body to which a discharge lamp is attached; and the discharge lamp lighting device according to claim 1, for lighting the discharge lamp.