JPH1167481A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which can prevent short circuiting electric current even at the time when a filament is short circuitted. SOLUTION: In the case filaments FL1, FL2 of a fluorescent lamp FL are short circuited due to life termination, filament preheating windings Tr1d, Tr1e are short circuited. Since the inverter transformer Tr1 is a completely coupling type with 0.9-1.0 coupling coefficient, no voltage is induced in the winding Tr1c for an electric power source due to the short circuit of the filament preheating windings Tr1d, Tr1e and no electric power is supplied to a base drive circuit 5 and switching of a transistor Q1 can not be carried out. The inverter circuit 2 is stopped and short circuit electric current is prevented from flowing in the inverter transformer Tr1 and consequently, heat generation of the transistor Q1 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a discharge lamp lighting device for lighting a discharge lamp.

[0002]

2. Description of the Related Art Conventionally, as a discharge lamp lighting device of this type, for example, a configuration shown in FIG. 4 is known.

In the discharge lamp lighting device shown in FIG. 4, a full-wave rectifier circuit 1 is connected to a commercial AC power supply e, and an output terminal of the full-wave rectifier circuit 1 is connected to a smoothing capacitor C1. Is connected to an inverter circuit 2.

[0004] A parallel resonance circuit 3 is connected to the inverter circuit 2. This parallel resonance circuit 3
A resonance inductance circuit 4 with a series circuit of a primary winding Tr1a of a leakage flux type inverter transformer Tr1 having a coupling coefficient of about 0.5 to 0.7, and a resonance capacitor C2 resonating with the resonance inductance circuit 4 have. A transistor Q1 is connected in series with the parallel resonance circuit 3.
Is connected. Further, a base drive circuit 5 as a control means is connected to the transistor Q1, and a start-up resistor R1 and a power supply winding Tr1c serving as a power supply provided in the inverter transformer Tr1 are connected to the base drive circuit 5. .

[0005] The secondary winding of the inverter transformer Tr1
A load circuit 6 is connected to Tr1b. The load circuit 6 has a fluorescent lamp FL, and a filament FL of the fluorescent lamp FL.
One end of FL2 is connected to each filament FL
1 and FL2 are connected to filament preheating windings Tr1d and Tr1e provided in the inverter transformer Tr1.

When the power is turned on, the starting resistor R1
, The base drive circuit 5 starts operating, the base drive circuit 5 causes the transistor Q1 to perform high-frequency switching operation, the primary winding Tr1a of the inverter transformer Tr1 of the resonance inductance circuit 4 of the parallel resonance circuit 3, and the resonance capacitor. Resonates with C2, inverter transformer Tr1
A voltage is induced in the filament preheating windings Tr1d and Tr1e of the fluorescent lamp FL to preheat the filaments FL1 and FL2 of the fluorescent lamp FL, and a resonance voltage is generated in the secondary winding Tr1b to generate the fluorescent lamp FL.
Is lit at high frequency. Further, the lighting of the fluorescent lamp FL is stabilized by the current limiting inductance generated by the leakage inductance of the inverter transformer Tr1.

[0007]

However, the above-described discharge lamp lighting device shown in FIG.
Is a leakage magnetic flux type and has leakage inductance. Therefore, when the filaments FL1 and FL2 of the fluorescent lamp FL are short-circuited at the end of life or the like, a state where a voltage is induced in the power supply winding Tr1c by the leakage inductance is maintained.
Since the base drive circuit 5 keeps switching the transistor Q1, a short circuit current may flow through the inverter transformer Tr1.

The present invention has been made in view of the above problems, and has as its object to provide a discharge lamp lighting device capable of preventing a short-circuit current even when a filament is short-circuited.

[0009]

According to a first aspect of the present invention, there is provided a discharge lamp lighting device including a primary winding and a secondary winding, and a discharge lamp having a filament connected to the secondary winding. A resonance inductance circuit having an inductor connected in series with a primary winding of the transformer, a resonance capacitor resonating with the resonance inductance circuit, and a high frequency connected to the resonance inductance circuit and having a high frequency by a switching operation. An inverter circuit having a switching element for generating a voltage; a control means for controlling the switching element; a power supply winding magnetically connected to the transformer by perfect coupling and serving as a power supply for the control means; A filament preheating winding magnetically connected by coupling to preheat the filament of the discharge lamp. One in which the. The switching element is controlled by control means using the resonance of the resonance inductance circuit and the resonance capacitor and the power supply winding as a power supply, and the filament is preheated by the filament preheating winding to illuminate the discharge lamp at a high frequency. When the filament is short-circuited, no short-circuit current flows and no voltage is induced in the control means because the transformer is of a perfect coupling type, so that the control means does not operate the switching element and prevents the inverter circuit from continuing to operate.

According to a second 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; and a second capacitor connected to the rectifier. And a partial smoothing circuit having an inductance element and a charging capacitor, connected in parallel to the second capacitor that charges the charging capacitor with a voltage lower than the maximum instantaneous voltage value of the output of the rectifier. A primary winding and a secondary winding, a primary winding of a fully coupled transformer connected to a discharge lamp having a filament on the secondary winding side, and an inductor connected in series to the primary winding. Resonance inductance circuit having the same, a resonance capacitor resonating with the resonance inductance circuit, and a switch connected to the resonance inductance circuit. An inverter circuit including a switching element that generates a high-frequency voltage by operation; a control unit that controls the switching element; a power supply winding that is magnetically connected to the transformer in a completely coupled manner and serves as a power supply of the control unit; A filament preheating winding that is magnetically connected to the transformer in a completely coupled manner and preheats the filament of the discharge lamp. The inverter circuit supplies the input current from the first capacitor and the second capacitor when the output level of the rectifier is equal to or higher than the charge level of the charging capacitor, and the output level of the rectifier is lower than the charge level of the charging capacitor. In some cases, the input current is supplied from the partial smoothing circuit, the switching element is controlled by control means using the resonance of the resonance inductance circuit and the resonance capacitor and the power supply winding as a power supply, and the filament is discharged while being preheated by the filament preheating winding. When the lamp is turned on at high frequency and the filament of the discharge lamp is short-circuited, the short-circuit current does not flow and the voltage is not induced in the control means because the transformer is a complete coupling type. To keep on operating.

According to a third aspect of the present invention, in the discharge lamp lighting device according to the first or second aspect, the resonance inductance circuit includes an inductor in parallel with a series circuit of the primary winding of the transformer and the inductor. It has the same function as the discharge lamp lighting device according to the first or second aspect.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A discharge lamp lighting device according to one embodiment of the present invention will be described below with reference to the drawings. Parts corresponding to those of the conventional example shown in FIG.

In the discharge lamp lighting device shown in FIG. 1, a full-wave rectifier circuit 1 as a rectifier is connected to a commercial AC power supply e, and an output terminal of the full-wave rectifier circuit 1 is connected to a smoothing capacitor C1. The inverter circuit 2 is connected to the capacitor C1.

The parallel resonance circuit 3 is connected to the inverter circuit 2. This parallel resonance circuit 3
An inductance circuit 4 for resonance with a series circuit of a first inductor L1 and a primary winding Tr1a of an inverter transformer Tr1 having a function as a leakage magnetic flux type inductor having a coupling coefficient of about 0.9 to 1.0; And a resonance capacitor C2 that resonates with the inductance circuit 4 for resonance.
A transistor Q1 as a switching element is connected in series to the parallel resonance circuit 3. Further, a base drive circuit 5 as a control means is connected to the transistor Q1, and a start-up resistor R1 and a power supply winding Tr1c serving as a power supply provided in the inverter transformer Tr1 are connected to the base drive circuit 5. .

The secondary winding of the inverter transformer Tr1
A load circuit 6 is connected to Tr1b. The load circuit 6 has a fluorescent lamp FL as a discharge lamp.
One end of each of the filaments FL1 and FL2 of the FL is connected, and each of the filaments FL1 and FL2 is connected to an inverter transformer Tr1.
Are connected to the filament preheating windings Tr1d and Tr1e.

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

First, power is supplied to the base drive circuit 5 via the starting resistor R1, and the transistor Q1 is turned on. As described above, when the transistor Q1 is turned on, the resonance capacitor C2, the first inductor L1 of the resonance inductance circuit 4, and the inverter transformer Tr1 are turned on.
Current flows through the primary winding Tr1a of the inverter transformer Tr1
A voltage is induced in the secondary winding Tr1b. By the parallel resonance of the resonance capacitor C2, the first inductor L1, and the primary winding Tr1a of the inverter transformer Tr1, a high-frequency voltage is induced in the filament preheating windings Tr1d, Tr1e and the secondary winding Tr1b, and the filaments FL1, FL2 The fluorescent lamp FL is turned on at a high frequency while preheating the lamp. Further, a voltage is also induced in the power supply winding Tr1c and serves as a power supply for the base drive circuit 5.

When the filaments FL1 and FL2 of the fluorescent lamp FL are short-circuited at the end of life, for example, the filament preheating windings Tr1d and Tr1e are short-circuited. However, since the inverter transformer Tr1 is of a complete coupling type, the filament preheating is performed. Due to the short-circuit of the windings Tr1d and Tr1e, no voltage is induced in the power supply winding Tr1c, power is not supplied to the base drive circuit 5 and the transistor Q1 cannot be switched, and the inverter circuit 2 stops and the inverter transformer
Short-circuit current does not flow through Tr1, preventing heat generation of transistor Q1.

Next, another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 2 differs from the embodiment shown in FIG. 1 in that a first capacitor C11 having a relatively large capacity is connected to the commercial AC power supply e, and the first capacitor C11 is connected to a full-wave capacitor. An input terminal of the rectifier circuit 1 is connected, and a series circuit of a second capacitor C12 having a smaller capacity than the first capacitor C11 is connected to an output terminal of the full-wave rectifier circuit 1,
The second capacitor C12 has a partial smoothing circuit 8 for valley filling.
Are connected. In the partial smoothing circuit 8, a charging capacitor C15, a series circuit of an inductor L2 and a diode D1 as an inductance element are connected to the output terminal of the full-wave rectifier circuit 1, and a connection point of the inductor L2 and the diode D1 A diode D2 is connected between the connection point of the capacitor C2 and the connection point of the transistor Q1.

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

First, power is supplied to the base drive circuit 5 via the starting resistor R1 and the transistor Q1 is turned on. Then, when the transistor Q1 is switched by the base drive circuit 5 and oscillates, the first inductor
L1, a high-frequency voltage is generated by the resonance action of the primary winding Tr1a of the inverter transformer Tr1, the charging capacitor C15, and the resonance capacitor C2, and a high-frequency voltage is also induced in the secondary winding Tr1b.

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 C15, the first inductor L1 and the diode D2, and the charging capacitor C1 is turned on.
5 is charged. Then, a DC voltage lower than the peak value of the pulsating voltage from the full-wave rectifier circuit 1 can be stored in the charging capacitor C15.

Here, a description will be given of a section where the pulsating voltage of the full-wave rectifier circuit 1 is higher than a charging voltage of the charging capacitor C15 and a section where the pulsating voltage is lower than the charging voltage of the charging capacitor C15.

First, when the transistor Q1 of the inverter circuit 2 is turned on at an arbitrary time in a section where the pulsating voltage of the full-wave rectifier circuit 1 is higher than the charging voltage of the charging capacitor C15, the primary winding Tr1a of the inverter transformer Tr1 is turned on. Most of the current is supplied from the first capacitor C11 and part of the current is supplied from the second capacitor C12, and is charged to the charging capacitor C15. Note that this full-wave rectifier circuit 1
Is not discharged from the charging capacitor C15 to the inverter circuit 2 in the section where the voltage value is high. The combined capacitance of the first capacitor C11 and the second capacitor C12 is sufficient to provide the energy required by the inverter circuit 2. In accordance with the current supply from the first capacitor C11 and the second capacitor C12, energy flows from the commercial AC power supply e side as an input current. The transistor Q1 responds to the change in the pulsating voltage.
, And the small and equal high-frequency amplitude of the inverter operation of the inverter circuit 2 is superimposed along the sine wave value of the AC voltage over the entire section where the voltage value of the full-wave rectifier circuit 1 is high. You.

That is, in a section where the voltage value of the full-wave rectifier circuit 1 is high, the first capacitor C11 and the second capacitor C11
12 is a value in which the energy given by the supplied pulsating voltage is satisfied with respect to the energy required by the inverter circuit 2.

Therefore, the first capacitor C11 and the second capacitor C11
Each of the capacitors C12 has a small ripple component, a small amount of heat generation, and can enhance the operation reliability.

Next, in a section where the voltage value of the full-wave rectifier circuit 1 is low, when the pulsating sine wave voltage of the full-wave rectifier circuit 1 starts to decrease with respect to the charging voltage of the charging capacitor C15, the transistor Q1 is turned on. When turned on, the inverter transformer Tr1
The current to the primary winding Tr1a is first supplied to the second capacitor C12
And a current flowing through the path of the charging capacitor C15, the inductor L2, the diode D1, and the transistor Q1, the charging capacitor C15 is charged, and the DC voltage lower than the peak value of the pulsating voltage from the full-wave rectifier circuit 1. Becomes Since the capacity of the second capacitor C12 is not enough to provide the energy required by the inverter circuit 2, the current of the second capacitor C12 increases as the current flowing through the primary winding Tr1a increases after the transistor Q1 is turned on. The voltage drops. And the voltage of the second capacitor C12 becomes the first
The first capacitor C11 supplies the energy to the inverter circuit 2 that is insufficient in the second capacitor C12 from the time when the voltage of the capacitor C11 drops to the voltage of the second capacitor C11.

Then, the voltage is supplied until the transistor Q1 is turned off, but the decrease in the voltage of the second capacitor C12 is reduced after the supply of energy from the first capacitor C11 is started. In addition, the energy supply from the first capacitor C11 to the inverter circuit 2 causes a corresponding amount of energy to flow as an input current from the commercial AC power supply e side.

On the other hand, the charging voltage of the charging capacitor C15 is delayed due to the transient impedance of the first inductor L1, the second inductor L3, and the primary winding Tr1a of the inverter transformer Tr1, so that the energy release is delayed, and immediately before the transistor Q1 turns off. It will release energy at that point. When the transistor Q1 turns off, the charging capacitor
The charging voltage of C15 depends on the first inductor L1, the primary winding Tr1a of the inverter transformer Tr1, the diode D1 and the second
Is a voltage supply source to the series circuit of the capacitor C12. Here, the first inductor L1 and the inverter transformer Tr
Since the series circuit of the primary winding Tr1a and the second capacitor C12 are set so as to obtain an oscillating resonance, the charging of the second capacitor C12 is performed in a sine wave shape. Then, this charging is performed in the inverter circuit 2.
When the transistor Q1 is turned on next time, the voltage is increased to a level at which the energy supply is not insufficient. Also transistors
By turning off Q1, the capacitor C2 and the first inductor L
1, second inductor L3 and inverter transformer Tr1
Resonates with the series circuit of the primary winding Tr1a. Then, this resonance current is supplied to the diode D1, the diode D2, the primary winding Tr1a of the inverter transformer Tr1, the second capacitor C12,
Then, the current flows through the path of the resonance capacitor C2, and the second capacitor C12 is charged to generate an oscillating voltage. At this time, the voltage across the second capacitor C12 has substantially the same voltage value at both the highest instantaneous voltage portion and the lowest instantaneous voltage portion of the commercial AC power supply e, and is close to the DC voltage.

Then, as the voltage of the first capacitor C11 decreases with respect to the charging voltage of the charging capacitor C15, the voltage of the second capacitor C12 decreases, and the amplitude due to the first inductor L1 and the second capacitor C12. Becomes larger. Further, although the input current decreases, the current flows continuously.

As described above, the continuous flow of the input current from the commercial AC power supply e prevents a harmonic component from intervening in the input current.

The operation when the filaments FL1 and FL2 are short-circuited basically operates in the same manner as the embodiment shown in FIG.

Another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 3 is different from the embodiment shown in FIG. 2 in that a second inductor L3 is connected in parallel to the resonance capacitor C2.

As described above, the same effect can be obtained even if the resonance inductance circuit 4 is formed including the second inductor L3.

[0037]

According to the discharge lamp lighting device of the first aspect, the filament is preheated by controlling the switching element by the control means using the resonance inductance circuit and the resonance capacitor and the power supply winding as a power supply. When the discharge lamp is turned on at a high frequency while being preheated by the winding, and the filament of the discharge lamp is short-circuited, the short-circuit current does not flow and the voltage is not induced in the control means because the transformer is a completely coupled type. Can be prevented from operating, and the inverter circuit can be prevented from continuing to operate.

According to the discharge lamp lighting device of the second aspect,
The inverter circuit supplies the input current from the first capacitor and the second capacitor when the output level of the rectifier is equal to or higher than the charge level of the charging capacitor, and partially supplies the input current when the output level of the rectifier is lower than the charge level of the charging capacitor. An input current is supplied from a smoothing circuit, and the switching element is controlled by control means using the resonance of the resonance inductance circuit and the resonance capacitor and the power supply winding as a power supply to control the discharge lamp while preheating the filament by the filament preheating winding. If the filament of the discharge lamp is short-circuited at high frequency and the transformer is completely coupled, no short-circuit current flows and no voltage is induced in the control means, so that the control means does not operate the switching element and the inverter circuit operates. Can be prevented from continuing.

According to the discharge lamp lighting device of the third aspect,
In addition to the discharge lamp lighting device according to claim 1 or 2, the resonance inductance circuit has an inductor in parallel with a series circuit of a primary winding of the transformer and the inductor, and the discharge lamp according to claim 1 or 2. The same effect as the lighting device can be obtained.

[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 circuit diagram showing a discharge lamp lighting device according to another embodiment of the present invention.

FIG. 3 is a circuit diagram showing a discharge lamp lighting device according to another embodiment of the present invention;

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Full-wave rectification circuit as rectification means 2 Inverter circuit 4 Resonance inductance circuit 5 Base drive circuit as control means 8 Partial smoothing circuit C2 Resonance capacitor C11 First capacitor C12 Second capacitor C15 Charging capacitor e Commercial AC Power supply FL Fluorescent lamp as discharge lamp FL1, FL2 Filament L1, L3 Inductor L2 Inductor as inductance element Q1 Transistor as switching element Tr1 Inverter transformer Tr1a having an inductor function Primary winding Tr1b Secondary winding Tr1c Winding for power supply Wire Tr1d, Tr1e Filament preheating winding

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Sugiyama 6-78, Minamicho, Mishima-shi, Shizuoka Pref.

Claims (3)

[Claims] 1. A fully-coupled transformer having a primary winding and a secondary winding, and a discharge lamp having a filament on the secondary winding side, and a series connection to the primary winding of the transformer. A resonance inductance circuit having an inductor, a resonance capacitor resonating with the resonance inductance circuit, and an inverter circuit having a switching element connected to the resonance inductance circuit and generating a high-frequency voltage by a switching operation; A power supply winding which is magnetically connected to the transformer in a completely coupled manner and serves as a power supply for the control means; and a magnetically connected in a completely coupled manner to the transformer to preheat the filament of the discharge lamp. A discharge lamp lighting device comprising a filament preheating winding. A first capacitor connected to the AC power supply, a rectifier connected to the first capacitor, a second capacitor connected to the rectifier, an inductance element and a charging capacitor. A partial smoothing circuit connected in parallel to the second capacitor for charging the charging capacitor with a voltage lower than the maximum instantaneous voltage value of the output of the rectifier; a primary winding and a secondary winding And a resonance inductance circuit having a primary winding of a fully coupled transformer connected to a discharge lamp having a filament on the secondary winding side, and an inductor connected in series to the primary winding. A resonance capacitor that resonates with the inductance circuit, and a high-frequency voltage generated by a switching operation connected to the resonance inductance circuit An inverter circuit having a switching element, a control means for controlling the switching element, a power supply winding magnetically connected to the transformer in a completely coupled manner and serving as a power supply for the control means, and a completely coupled to the transformer. And a filament preheating coil magnetically connected to preheat a filament of the discharge lamp. 3. The resonance inductance circuit has an inductor in parallel with a series circuit of a primary winding of the transformer and the inductor.
The discharge lamp lighting device as described in the above.