JPH11162680A - Discharge-lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge-lamp lighting device capable of surely producing a start voltage. SOLUTION: When a transistor Q1 is turned on by a control circuit 5, current flows through a capacitor C2, and through a first inductor L1, a second inductor L2, and a primary winding Tr1a of an inverter transformer Tr1, whereby voltage is induced in a secondary winding Tr1b and a detection winding Tr1c of the inverter transformer Tr1, respectively. A fluorescent lamp FL is high-frequency lit based on the voltage induced in the secondary winding Tr1b by parallel resonance of the capacitor C2, the first inductor L1, the second inductor L2, and the primary winding Tr1a of the inverter transformer Tr1. The voltage induced in the secondary winding Tr1b is produced in a resistor R2 by way of the detection winding Tr1c, this voltage is detected by a detection circuit 7, the voltage of the resistor R2 is kept constant by the control circuit 5 if an inductance circuit 4 for resonance, the capacitor C2 for resonance, a capacitor C3, and other components have dispersion in their values, whereby voltage applied to the fluorescent lamp FL is kept constant, and thus its starting and lighting are made certain.

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 capable of reliably obtaining a starting voltage of 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
Primary winding of inductor L1 and inverter transformer Tr1
It has a resonance inductance circuit 4 with the series circuit of Tr1a, and a resonance capacitor C2 that resonates with the resonance inductance circuit 4. A transistor Q1 is connected in series to the parallel resonance circuit 3. Further, a control circuit 5 is connected to the transistor Q1.

[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.
1 and FL2 are connected to one end, and the other end of the filaments FL1 and FL2 is connected to a starting capacitor C3.

Then, when the power is turned on, the starting resistor is turned on.
The control circuit 5 starts operating via R1, the transistor Q1 performs high-frequency switching operation by the control circuit 5, and the primary winding Tr1a, the inductor L1, and the capacitor of the inverter transformer Tr1 of the resonance inductance circuit 4 of the parallel resonance circuit 3 are connected. Resonant with C2, secondary winding of inverter transformer Tr1
A resonance voltage is generated in Tr1b, and the fluorescent lamp FL is stably turned on at a high frequency by the current limiting inductance generated by the leakage inductance of the inverter transformer Tr1.

[0007]

However, in the discharge lamp lighting device shown in FIG. 4, when starting the fluorescent lamp FL, the fluorescent lamp FL is caused by variations in the components of the capacitor C3, the inductor L1, the transistor Q1, and the capacitor C2.
There is a problem that a sufficient starting voltage of the FL may not be obtained.

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 reliably obtaining a starting voltage.

[0009]

According to a first aspect of the present invention, there is provided a discharge lamp lighting device connected to a discharge lamp, a resonance inductor, a resonance capacitor resonating with the resonance inductor, and a switching connected to the resonance inductor. An inverter circuit having a switching element that generates a high-frequency voltage by operation; a detection winding that is magnetically coupled to the resonance inductor to detect a voltage; and a voltage of the detection winding based on the voltage detected by the detection winding. Control means for controlling the switching element so that the voltage generated in the resonance inductor is detected by the detection winding, and the control means controls the voltage of the detection winding to a constant value based on the detected voltage. Therefore, a predetermined voltage can be reliably obtained, and the discharge lamp is reliably started and lit.

According to a second aspect of the present invention, there is provided a discharge lamp lighting device, comprising: a rectifier for rectifying an AC from an AC power supply; a first capacitor connected in parallel to an output terminal of the rectifier; One end has a diode connected in series with forward polarity, a second capacitor connected in parallel to the first capacitor via the diode, an inductance element and a charging capacitor. A partial smoothing circuit connected in parallel to the second capacitor for charging with a voltage lower than the maximum instantaneous voltage value of the output of the rectifier, a discharge lamp connected to the resonance inductor, and resonating with the resonance inductor; A resonance capacitor, and a switching element connected to the resonance inductor and generating a high-frequency voltage by a switching operation. An inverter circuit, a detection winding that is magnetically coupled to the resonance inductor and detects a voltage, and control means that controls the switching element to keep the voltage of the detection winding constant based on the voltage detected by the detection winding. And a rectifier, a first capacitor, a diode, a second capacitor and a charging capacitor,
In addition to increasing the power factor and reducing harmonics, the detection winding detects the voltage generated in the resonance inductor, and based on the detected voltage, the control means performs switching to keep the voltage of the detection winding constant. Since the elements are controlled, a predetermined voltage can be reliably obtained, and the discharge lamp is reliably started and lit.

According to a third 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 resonance inductor to which a discharge lamp is connected, a resonance capacitor that resonates with the resonance inductor, and an inverter circuit having a switching element that is connected to the resonance inductor and generates a high-frequency voltage by a switching operation. A detection winding that is magnetically coupled and detects a voltage, and a detection winding based on the voltage detected by the detection winding. Control means for controlling the switching element to keep the voltage of the output winding constant. The first capacitor, the rectifier, the second capacitor and the charging capacitor increase the power factor and reduce harmonics. In addition to reducing the voltage, the voltage generated in the resonance inductor is detected by the detection winding, and based on the detected voltage, the control means controls the switching element so as to keep the voltage of the detection winding constant. Voltage can be obtained, and the discharge lamp is reliably started and lit.

[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.

As shown in FIG. 1, an input terminal of a full-wave rectifier circuit 1 as a rectifier of a diode bridge is connected to a commercial AC power supply e, and a smoothing capacitor C1 is connected to an output terminal of the full-wave rectifier circuit 1. It is connected.

An inverter circuit 2 as a power supply is connected to the capacitor C1. In the inverter circuit 2, a series circuit of a parallel resonance circuit 3 of a resonance capacitor C2, a resonance inductance circuit 4 as a resonance inductor, and a transistor Q1 as a switching element is connected in parallel to the capacitor C1. An inductance circuit 4 has a second inductor L2 connected in parallel with the capacitor C2, and a primary winding of the first inductor L1 and a tightly coupled insulated inverter transformer Tr1 connected in parallel with the second inductor L2. It has a series circuit of the line Tr1a.

Further, a control circuit 5 as control means is connected to the base of the transistor Q1 and is connected to the full-wave rectifier circuit 1 via a starting resistor R1. A detection winding Tr1c magnetically coupled to the inverter transformer Tr1 is connected via a voltage detection resistor R2.

Further, filaments FL1 and FL2 of a fluorescent lamp FL as a discharge lamp are connected to the secondary winding Tr1b of the inverter transformer Tr1.
, FL2 is connected to a starting capacitor C3.

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

First, the control circuit 5 is connected via a starting resistor R1.
, And the transistor Q1 is turned on. As described above, when the transistor Q1 is turned on, current flows through the capacitor C2, the first inductor L1, the second inductor L2, and the primary winding Tr1a of the inverter transformer Tr1, and the secondary winding Tr1b of the inverter transformer Tr1. And a voltage is induced in the detection winding Tr1c. And the capacitor C2,
Based on the voltage induced in the secondary winding Tr11b by the parallel resonance of the first inductor L1, the second inductor L2 and the primary winding Tr1a of the inverter transformer Tr1, the fluorescent lamp FL
Is lit at high frequency.

Further, a voltage induced in the secondary winding Tr1b is detected by the detection winding Tr1c, a voltage is generated in the detection resistor R2, and this voltage is detected by the detection circuit 7, and temporarily the resonance inductance circuit is detected. 4. Even if components such as the resonance capacitors C2 and C3 vary, the control circuit 5 controls the transistor Q1 so that the voltage of the resistor R2 is constant, and the voltage applied to the fluorescent lamp FL is controlled. And ensure that the fluorescent lamp FL is started and lit.

Note that the voltage of the resistor R2 is Vc, and the secondary winding Tr1b
Is Nb and the number of turns of the detection winding Tr1c is Nc, the voltage Vb of the secondary winding Tr1b becomes Vb = (Nb / NC) Vc, and Nb / NC is constant. Thus, the voltage Vb can be controlled to be constant.

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

In the embodiment shown in FIG. 2, a first capacitor C11 having a relatively large capacitance is connected to the output terminal side of the full-wave rectifier circuit 1 in the embodiment shown in FIG. A series circuit of a diode D11 and a second capacitor C12 having a smaller capacity than the first capacitor C11 is connected to the capacitor C11, and a partial smoothing circuit 8 is connected in parallel to the second capacitor C12. This partial smoothing circuit 8
Connects a second capacitor C12 to a series circuit of a charging capacitor C15, an inductor L5, and a diode D12,
A diode D12 is connected between a connection point between the inductor L5 and the diode D12 and a connection point between the capacitor C2 and the transistor Q1.

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

First, when power is supplied to the control circuit 5 via the resistor R1, the transistor Q1 is turned on, and the control circuit 5 causes the transistor Q1 to perform a switching operation and oscillate, whereby the first inductor L1, the second inductor L2, primary winding Tr1a of inverter transformer Tr1 and charging capacitor C1
A high-frequency voltage is generated by the resonance action with the capacitor 5 and the resonance capacitor C2, and the high-frequency voltage is also induced in the secondary winding Tr1b.

When the transistor Q1 is turned on, the first
Current flows through the inductor L1 and the primary winding Tr1a of the inverter transformer Tr1 and the charging capacitor C15,
A current flows through the second inductor L2 and the diode D12 to charge the charging capacitor C15. And
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.

A description will now be given of a section in which the pulsating voltage of the full-wave rectifier circuit 1 is higher than the charging voltage of the charging capacitor C15 and a section in which 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 the combined capacitance of the first capacitor C11 and the second capacitor C12 is
The capacity 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 from the commercial AC power source e flows 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 2 along the sine wave value of the AC voltage becomes full-wave. The voltage value of the rectifier circuit 1 is superimposed on all high sections.

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 C
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.

Then, in a section where the voltage value of the full-wave rectifier circuit 1 is high, the charging capacitor C15 is charged when the transistor Q1 is turned off. Note that, in the section where the voltage value of the full-wave rectifier circuit 1 is high, the discharge is not performed from the charging capacitor C15 to the inverter circuit 2 side.

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 the charging capacitor C15, the first
Current flows through the path of the inductor L1, the second inductor L2, the primary winding Tr1a of the inverter transformer Tr1, the diode D12 and the transistor Q1, and the charging capacitor C15
Is charged, and becomes a DC voltage lower than the peak value of the pulsating voltage from the full-wave rectifier circuit 1. And the second capacitor C1
Since the capacity of 2 is not enough to provide the energy required by the inverter circuit 2, the voltage of the second capacitor C12 decreases as the current flowing through the primary winding Tr1a increases after the transistor Q1 turns on. When the voltage of the second capacitor C12 drops to the voltage of the first capacitor C11, the first capacitor C11 supplies energy to the inverter circuit 2 which is insufficient in the second capacitor C12.

Then, the voltage is supplied until the transistor Q1 is turned off. However, since the supply of energy from the first capacitor C11 is started, the decrease in the voltage of the second capacitor C12 is reduced. 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 L2, and the primary winding Tr1a of the inverter transformer Tr1, and the energy release is delayed. It will release energy at that point. When the transistor Q1 turns off, the charging capacitor
The charging voltage of C15 serves as a voltage supply source for a series circuit of the first inductor L1, the second inductor L2, the primary winding Tr1a of the inverter transformer Tr1, the diode D12 and the second capacitor C12. Here, the series circuit of the first inductor L1, the second inductor L2, the primary winding Tr1a of the inverter transformer Tr1, and the second capacitor C12 are set so as to obtain oscillation resonance. 2
Is charged to the capacitor C12 in a sinusoidal waveform. This charging is increased in the inverter circuit 2 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, the capacitor C2, the first inductor L1, the second inductor L2 and the primary winding of the inverter transformer Tr1 are turned off.
Resonates with the series circuit of Tr1a. Then, this resonance current flows through the path of the diode D12, the diode D13, the primary winding Tr1a of the inverter transformer Tr1, the second capacitor C12, and the 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 second inductor L2 and the second capacitor C2. Becomes larger.
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.

The operation of the inverter circuit 2 and other operations is basically the same as that of the embodiment shown in FIG.

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

The embodiment shown in FIG. 3 differs from the embodiment shown in FIG.
The full-wave rectifier circuit 1 is connected between the capacitor C11 and the second capacitor C12.

As described above, by eliminating the diode D11, the circuit configuration can be simplified while the basic operation is substantially the same.

[0040]

According to the discharge lamp lighting device of the first aspect, the voltage generated in the resonance inductor is detected by the detection winding, and the control means keeps the voltage of the detection winding constant based on the detected voltage. Therefore, a predetermined voltage can be reliably obtained, and the discharge lamp can be reliably started and lit.

According to the discharge lamp lighting device of the second aspect,
The rectifier, the first capacitor, the diode, the second capacitor, and the charging capacitor increase the power factor and reduce harmonics, and detect the voltage generated in the resonance inductor by the detection winding. Since the control means controls the switching element so as to keep the voltage of the detection winding constant based on the applied voltage, a predetermined voltage can be reliably obtained, and the discharge lamp can be reliably started and lit.

According to the discharge lamp lighting device of the third aspect,
The first capacitor, the rectifier, the second capacitor, and the charging capacitor increase the power factor and reduce harmonics, detect the voltage generated in the resonance inductor by the detection winding, and detect the detected voltage. The control means controls the switching element so as to keep the voltage of the detection winding constant based on the voltage, so that a predetermined voltage can be reliably obtained, and the discharge lamp can be reliably started and lit.

[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 as resonance inductor 5 Control circuit as control means 8 Partial smoothing circuit C11 First capacitor C12 Second capacitor C15 Charging capacitor D11 Diode e Commercial AC power supply FL Fluorescent lamp as discharge lamp Q1 Transistor Tr1c as switching element Detection winding

Claims (3)

[Claims] An inverter circuit having a resonance inductor to which a discharge lamp is connected, a resonance capacitor to resonate with the resonance inductor, and a switching element connected to the resonance inductor to generate a high-frequency voltage by a switching operation; A detection winding that is magnetically coupled to the resonance inductor and detects a voltage; and a control unit that controls the switching element to keep the voltage of the detection winding constant based on the voltage detected by the detection winding. Discharge lamp lighting device characterized by the above-mentioned. 2. A rectifier for rectifying an AC from an AC power supply, a first capacitor connected in parallel to an output terminal of the rectifier, and one end of the first capacitor connected in series with a forward polarity. A second capacitor connected in parallel to the first capacitor via the diode, an inductance element and a charging capacitor, and the charging capacitor has a maximum instantaneous voltage of the output of the rectifier means. A partial smoothing circuit connected in parallel to the second capacitor charged at a voltage lower than a value, a resonance inductor connected to a discharge lamp, a resonance capacitor resonating with the resonance inductor, and a resonance capacitor An inverter circuit having a switching element connected to the inductor and generating a high-frequency voltage by a switching operation; A detection winding that is magnetically coupled to the inductor and detects a voltage, and control means for controlling the switching element to keep the voltage of the detection winding constant based on the voltage detected by the detection winding. Discharge lamp lighting device. 3. A first capacitor connected to an 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, and a resonance inductor connected to a discharge lamp. A resonance capacitor that resonates with the resonance inductor, an inverter circuit that is connected to the resonance inductor and generates a high-frequency voltage by a switching operation, and a voltage that is magnetically coupled to the resonance inductor to detect a voltage. A detection winding, and the voltage of the detection winding is kept constant based on the voltage detected by the detection winding. A discharge lamp lighting device, comprising: control means for controlling the switching element.