JPH10340790A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which can cope with both at the time of preheating and the terminal stage of life, with a simple circuit configuration. SOLUTION: A transistor Q8 is turned on and bypasses a resistance R24 at the time of preheating. A voltage lower than that in a normal lighting period is impressed on the gate of a field effect transistor Q2, a base current is supplied to the base of a transistor Q1 according to composite capacitance of capacitors C7, C8 and a capacitor C11 according to an on-resistance of the field effect transistor Q2, its output is delivered in such a state that it is suitable for preheating, filaments FL1a, FL1b, FL2a, FL2b are preheated at appropriate voltages. At the time of starting and lighting, a base current is supplied to the base of the transistor Q1 according to a composite capacitance of the capacitors C7, C8 and of the capacitor C11 according to an on-resistance of the field effect transistor Q2, and its output is increased. In the terminal stage of its life time, an output which is still lower than that of the time of preheating is delivered by turning off the field effect transistor Q2, whereby fluorescent lamps FL1, FL2 are turned off.

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 provided with a discharge lamp lighting circuit for lighting a discharge lamp having a filament.

[0002]

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

In the discharge lamp lighting device shown in FIG. 2, a filter circuit 1 is connected to a commercial AC power supply e via a fuse F, and the filter circuit 1 includes a capacitor C1 and a constant voltage element.
Z1, a transformer Tr1, an inductor L1, and a capacitor C2. The filter circuit 1 includes diodes D1, D2, D
The input side of the full-wave rectifier circuit 2 of the bridge of D3 and D4 is connected to the output side of the full-wave rectifier circuit 2, and a parallel circuit of a constant voltage element Z2 and a capacitor C3 is connected.

A capacitor C4 is connected to the capacitor C3 via a diode D5, and a partial smoothing circuit 3 is connected in parallel to the capacitor C4. The partial smoothing circuit 3 includes an inductor L2, a capacitor C5 and a diode D6.
Series circuit is connected, capacitor C5 and diode
The diode D7 is connected to the connection point of D6.

The partial smoothing circuit 3 is connected to a one-piece inverter circuit 4 as a discharge lamp lighting circuit. The inverter circuit 4 includes a primary winding Tr2a of an inverter transformer Tr2 and a resonance capacitor C6. Parallel resonance circuit 5
And the collector and the emitter of the transistor Q1 are connected in series. Further, a series circuit of a resistor R1 and a capacitor C7 is connected in parallel with the capacitor C3, and a connection point of the resistor R1 and the capacitor C7 is connected to a base of the transistor Q1 via a resistor R2. A drive circuit 6 is connected between the base and the emitter of the transistor Q1, and a variable capacitance circuit 7 is connected to the drive circuit 6 via a diode D8 and a control winding CT1b of a current transformer CT1. 7 is a series circuit of a capacitor C7 and a capacitor C8, and a capacitor C11 and a field-effect transistor connected in parallel to the series circuit.
A series circuit of Q2 is connected, and a variable capacitor 8 is formed by the series circuit of the capacitor C11 and the field effect transistor Q2.
Is formed. A diode D11 and a diode D12 are connected in anti-parallel to the capacitor C7, a diode D13 is connected in parallel to the capacitor C8, and the control winding CT1b has a diode D14 and a diode in series with the diode D11. D15 is connected in series.

Further, one end of the filaments FL1a, FL2b of the fluorescent lamps FL1, FL2 is connected to a secondary winding Tr2b of the inverter transformer Tr2 via a series circuit of a detection winding CT1a of the current transformer CT1 and a DC cut capacitor C12. The starting capacitor C14 is sequentially connected between the other ends of the filaments FL1a and FL1b of the fluorescent lamp FL1, and the starting capacitor C15 is connected to the other ends of the filaments FL1a and FL2b of the fluorescent lamps FL1 and FL2. Have been. In addition, a filament preheating winding Tr2c is provided in the inverter transformer Tr2, and the filament preheating winding Tr2c is a fluorescent lamp.
It is connected to filaments FL1b and FL2a of FL1 and FL2.

An end-of-life detection circuit 11 is connected in parallel with the detection winding CT1a of the current transformer CT1, and this end-of-life detection circuit 11 is connected in parallel with the detection winding CT1a by a resistor R3.
And a series circuit of a resistor R4. Both ends of the resistor R3 and the resistor R4 are connected through rectifying diodes D15 and D16, the resistor R5 and the capacitor C16, and the resistor R3 is connected.
And the connection point of the resistor R4. In addition, a resistor R6 and a programmable resistor
A series circuit of a unijunction transistor (PUT) Q3 and a light emitting diode LED1, and a series circuit of a resistor R7 and a zener diode ZD1 are connected. A capacitor C17 is connected in parallel with the resistor R6, and a resistor R6 and a zener diode ZD1 are connected. Is connected to the gate of a programmable unijunction transistor (PUT) Q3.

Further, a capacitor C14 and a capacitor
A series circuit of resistors R18 and R19 is connected to the connection point of C15, and a diode D1 is connected in parallel with the capacitor C19.
7 is connected, and the connection point of the capacitor C18 and the capacitor C19 is programmable via a diode D18.
It is connected to the anode of a unijunction transistor (PUT) Q3.

A resistor is connected in parallel with the capacitor C3.
A series circuit of R11 and a capacitor C21 is connected in parallel with a series circuit of a resistor R12 and a capacitor C22, and a preheating circuit 12 is connected in parallel to the capacitor C22. In this preheating circuit 12, a series circuit of a resistor R13 and a capacitor C23 is connected in parallel with the capacitor C22, and the Zener diode ZD is connected in parallel with the capacitor C23.
2 and a series circuit of a capacitor C24, a resistor R14 is connected in parallel with the capacitor C24, and a transistor Q4 is connected to a connection point between the zener diode ZD2 and the capacitor C23.

Further, in parallel with the capacitor C21,
A series circuit of a resistor R15, a diode D21 and a capacitor C25 is connected, a phototransistor Q5 photocoupled to the light emitting diode LED1 is connected in parallel with the resistor R15 and the diode D21, and a resistor R16 is connected in parallel with the capacitor C25. Is connected, and the capacitor C2
Resistor R17 and Zener diode ZD3 in parallel with 1
The collector and the emitter of the transistor Q6 are connected in parallel to the Zener diode ZD3, and the base of the transistor Q6 is connected to the connection point of the emitter of the phototransistor Q5 and the resistor R16.

A resistor R21, an emitter and a collector of the transistor Q7, and a resistor R2 are connected in parallel with the capacitor C21.
2, a series circuit of a resistor R23 and a resistor R24 is connected, and the base of the transistor Q7 is connected via a resistor R26 to a connection point of the resistor R12 and the capacitor C22. further,
A parallel circuit of a capacitor C26 and a resistor R27 is connected between the base of the transistor Q7 and the resistor R24. A capacitor C27 is connected in parallel to the series circuit of the resistors R23 and R24, and the resistors R22 and R2 are connected in parallel.
3 is connected to the field effect transistor Q2 via a resistor R28.
Are connected, and these constitute the control circuit 15.

Then, the AC voltage of the commercial AC power supply e is full-wave rectified by the full-wave rectifier circuit 2 via the filter circuit 1, and a DC voltage is supplied to the inverter circuit 4. At this time, diode D5, capacitors C3, C4, C5 and inductor L2
To improve the efficiency by superimposing the high frequency and shaping the waveform,
Harmonics are reduced. In addition, the capacitor C7 is charged with a time constant set by the resistor R1 and the capacitor C7, a base current for starting is supplied via the resistor R2, and the transistor Q1 is turned on. Then, based on the parallel resonance circuit 5 and the control winding CT1b of the lamp current detected by the detection winding CT1a, the transistor Q1 opens and closes.

After power is turned on, the capacitor C23 is charged with the time constant of the resistor R13 and the capacitor C23, and the transistor Q4 is off until the zener diode ZD2 is turned on. Therefore, a base current is supplied to the transistor Q6. As a result, the transistor Q6 turns on and the collector has a higher potential than the emitter of the transistor Q7.
Q7 remains off, no voltage is applied to the gate of field effect transistor Q2, and capacitor C11 is apparently not connected, so transistor Q1 is driven with a relatively low base current and the output of inverter circuit 4 is suppressed. To be
The fluorescent lamp FL1 does not start and the filaments FL1a, FL1b, F
L2a and FL2b are preheated respectively.

Thereafter, when the capacitor C23 is charged and the Zener diode ZD2 is turned on, the transistor Q4 is turned on, the base current of the transistor Q6 is bypassed, the transistor Q6 is turned off, and the collector voltage becomes higher than the base of the transistor Q7. Transistor Q7 turns on and applies a gate voltage to the gate of field effect transistor Q2,
Capacitor C11 and apparently capacitor C7 and capacitor
Connect in parallel with the series circuit of C8 to increase the base current of transistor Q1. Therefore, the inverter transformer Tr2
A relatively high voltage is induced in the secondary winding Tr2b, and the fluorescent lamps FL1 and FL2 are started. In this state, the capacitor C17 is not sufficiently charged, the programmable unijunction transistor Q3 does not turn on, the light-emitting diode LED1 does not emit light, and the phototransistor Q5 maintains the off state. Is not performed.

When the fluorescent lamps FL1 and FL2 are turned on, the base current of the transistor Q1 is suppressed as compared with that at the time of starting, so that an appropriate voltage is applied to the fluorescent lamps FL1 and FL2.

When the fluorescent lamps FL1 and FL2 enter a half-wave discharge state at the end of life or the like, the voltage of the capacitor C12 increases, the voltage of the capacitor C16 increases, and the programmable unijunction transistor Q3 turns on. When the light-emitting diode LED1 emits light, the phototransistor Q5 turns on, the transistor Q6 turns on, and the transistor Q7 and the field-effect transistor Q2 turn off, so that the base current of the transistor Q1 decreases as in the case of preheating. As a result, the output of the inverter circuit 4 decreases.

On the other hand, the filaments FL1a, FL1b, FL2a, FL2b of the fluorescent lamps FL1, FL2 are emitterless, and so on.
When the voltage between both ends of the fluorescent lamps FL1 and FL2 rises, the voltage of the capacitors C18 and C19 rises, turning on the programmable unijunction transistor Q3 and lowering the output of the inverter circuit 4.

[0018]

As described above, the output of the inverter circuit 4 is equal between the preheating and the end of the life of the fluorescent lamps FL1 and FL2 by controlling the field effect transistor Q2 by the transistor Q7. If the output is sufficient for the preheating of FL1 and FL2, the fluorescent lamps FL1 and FL2
Output is not enough at the end of the life of the fluorescent lamp FL1
, FL2 at the end of its life, the filaments FL1a, FL1 can be sufficiently heated when the fluorescent lamps FL1, FL2 are preheated.
Preheating of b, FL2a, FL2b becomes insufficient.

It is also conceivable to connect a capacitor and a field effect transistor in correspondence with the preheating and the end of life of the fluorescent lamps FL1 and FL2, however, there is a problem that the circuit configuration becomes complicated.

The present invention has been made in view of the above problems, and has as its object to provide a discharge lamp lighting device which has a simple circuit configuration and can cope with both preheating and end of life.

[0021]

A discharge lamp lighting device according to the present invention has an inverter circuit for operating a transistor to light a discharge lamp having a filament, a variable capacitor and a variable capacitance circuit for the capacitor. A drive circuit that controls the transistor by changing the capacity of the discharge lamp; a preheating circuit that detects a predetermined time after the discharge lamp is started; an end-of-life detection circuit that detects the end of the life of the discharge lamp; In the preheating state, the variable capacitance circuit is controlled using a variable capacitor and a capacitor having a reduced capacity, and during normal lighting, the variable capacitance circuit is controlled using a variable capacitor and a capacitor having a larger capacity than in the preheating state. Let
In the end-of-life state detected by the end-of-life detection circuit in the end-of-life state, the variable capacitance circuit has a control circuit for controlling using a capacitor, and the control circuit is in a preheating state in which preheating is performed by a preheating circuit. The variable capacitance circuit is controlled using a variable capacitor and a capacitor with a reduced capacity.At normal lighting, the variable capacitance circuit is controlled using a variable capacitor and a capacitor with a larger capacity than in a preheated state, and the end of life is detected by an end of life detection circuit. In the end-of-life state detected, the variable capacity circuit is controlled using a capacitor, so the output of the inverter circuit at the end of life is reduced compared to that at preheating, without complicating the circuit configuration, so that it is properly Preheat and do not increase output more than necessary at the end of life.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the discharge lamp lighting device according to the present invention will be described with reference to the drawings. The portions corresponding to the conventional example shown in FIG.

In the discharge lamp lighting device shown in FIG. 1, a filter circuit 1 is connected to a commercial AC power supply e via a fuse F. The filter circuit 1 comprises a capacitor C1, a constant voltage element
Z1, a transformer Tr1, an inductor L1, and a capacitor C2. The filter circuit 1 includes diodes D1, D2, D
The input side of the full-wave rectifier circuit 2 of the bridge of D3 and D4 is connected to the output side of the full-wave rectifier circuit 2, and a parallel circuit of a constant voltage element Z2 and a capacitor C3 is connected.

A capacitor C4 is connected to the capacitor C3 via a diode D5, and a partial smoothing circuit 3 is connected in parallel to the capacitor C4. The partial smoothing circuit 3 includes an inductor L2, a capacitor C5 and a diode D6.
Series circuit is connected, capacitor C5 and diode
The diode D7 is connected to the connection point of D6.

The partial smoothing circuit 3 is connected to a one-piece inverter circuit 4 as a discharge lamp lighting circuit. The inverter circuit 4 includes a primary winding Tr2a of an inverter transformer Tr2 and a resonance capacitor C6. Parallel resonance circuit 5
And the collector and the emitter of the transistor Q1 are connected in series. Further, a series circuit of a resistor R1 and a capacitor C7 is connected in parallel with the capacitor C3, and a connection point of the resistor R1 and the capacitor C7 is connected to a base of the transistor Q1 via a resistor R2. A drive circuit 6 is connected between the base and the emitter of the transistor Q1, and a variable capacitance circuit 7 is connected to the drive circuit 6 via a diode D8 and a control winding CT1b of a current transformer CT1. 7 is a series circuit of a capacitor C7 and a capacitor C8, and a capacitor C11 and a field-effect transistor connected in parallel to the series circuit.
A series circuit of Q2 is connected, and the series circuit of the capacitor C11 and the field effect transistor Q2 forms a variable capacitor 8 whose apparent capacitance changes due to a change in the on-resistance of the field effect transistor Q2. Diodes D11 and D12 are connected in antiparallel to capacitor C7, diode D13 is connected in parallel to capacitor C8, and diode D11 is connected to control winding CT1b.
And a diode D14 and a diode D15 are connected in series.

Further, the filament FL1 of the fluorescent lamps FL1 and FL2 serving as discharge lamps is connected to the secondary winding Tr2b of the inverter transformer Tr2 via a series circuit of the detection winding CT1a of the current transformer CT1 and a capacitor C12 for cutting DC.
a, FL2b is connected to one end of the filament FL1a, and the other end of the filament FL1a, FL1b of the fluorescent lamp FL1 is sequentially connected with a capacitor C1 for starting.
4 is connected to the filament FL of the fluorescent lamps FL1 and FL2.
A starting capacitor C15 is connected to the other ends of 1a and FL2b. Further, a filament preheating winding Tr2c is provided in the inverter transformer Tr2, and the filament preheating winding Tr2c is connected to the filaments FL1b and FL1b of the fluorescent lamps FL1 and FL2.
Connected to FL2a.

An end-of-life detection circuit 11 is connected in parallel with the detection winding CT1a of the current transformer CT1, and this end-of-life detection circuit 11 is connected in parallel with the detection winding CT1a by a resistor R3.
And a series circuit of a resistor R4. Both ends of the resistor R3 and the resistor R4 are connected through rectifying diodes D15 and D16, the resistor R5 and the capacitor C16, and the resistor R3 is connected.
And the connection point of the resistor R4. In addition, a resistor R6 and a programmable resistor
A series circuit of a unijunction transistor (PUT) Q3 and a light emitting diode LED1, and a series circuit of a resistor R7 and a zener diode ZD1 are connected. A capacitor C17 is connected in parallel with the resistor R6, and a resistor R6 and a zener diode ZD1 are connected. Is connected to the gate of a programmable unijunction transistor (PUT) Q3.

Further, a capacitor C14 and a capacitor
A series circuit of resistors R18 and R19 is connected to the connection point of C15, and a diode D1 is connected in parallel with the capacitor C19.
7 is connected, and the connection point of the capacitor C18 and the capacitor C19 is programmable via a diode D18.
It is connected to the anode of a unijunction transistor (PUT) Q3.

Further, a resistor is connected in parallel with the capacitor C3.
A series circuit of R11 and a capacitor C21 is connected in parallel with a series circuit of a resistor R12 and a capacitor C22, and a preheating circuit 12 is connected in parallel to the capacitor C22. In this preheating circuit 12, a series circuit of a capacitor C31 and a resistor R31 is connected in parallel with the capacitor C22, and a connection point between the capacitor C31 and the resistor R31 is connected to the base of a transistor Q8.
A resistor R24 is connected between the collector and the emitter of the transistor.

Further, in parallel with the capacitor C21,
A series circuit of a resistor R15, a diode D21 and a capacitor C25 is connected, a phototransistor Q5 photocoupled to the light emitting diode LED1 is connected in parallel with the resistor R15 and the diode D21, and a resistor R16 is connected in parallel with the capacitor C25. Is connected, and the capacitor C2
Resistor R17 and Zener diode ZD3 in parallel with 1
The collector and the emitter of the transistor Q6 are connected in parallel to the Zener diode ZD3, and the base of the transistor Q6 is connected to the connection point of the emitter of the phototransistor Q5 and the resistor R16.

A resistor R21, an emitter and a collector of the transistor Q7, and a resistor R2 are connected in parallel with the capacitor C21.
2, a series circuit of a resistor R23 and a resistor R24 is connected, and the base of the transistor Q7 is connected via a resistor R26 to a connection point of the resistor R12 and the capacitor C22. further,
A parallel circuit of a capacitor C26 and a resistor R27 is connected between the base of the transistor Q7 and the resistor R24. A capacitor C27 is connected in parallel to the series circuit of the resistors R23 and R24, and the resistors R22 and R2 are connected in parallel.
3 is connected to the field effect transistor Q2 via a resistor R28.
Are connected, and these constitute the control circuit 15.

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

First, the AC voltage of the commercial AC power supply e is full-wave rectified by the full-wave rectifier circuit 2 via the filter circuit 1, and a DC voltage is supplied to the inverter circuit 4. At this time, the high frequency is superimposed by the diode D5, the capacitors C3, C4, C5, and the inductor L2 to shape the waveform, thereby improving the efficiency and reducing the harmonics. Also, a resistor R1 and a capacitor
The capacitor C7 is charged with the time constant set by C7,
Supply base current for starting via R2,
Turn on Q1. Then, the parallel resonance circuit 5 and the detection winding
Based on the control winding CT1b of the lamp current detected by CT1a,
The transistor Q1 opens and closes.

After the power is turned on, the capacitor C31 is charged by the time constant of the capacitor C31 and the resistor R31 until the capacitor C31 is charged.
The base current is supplied to the transistor Q8 and the transistor
Q8 turns on and resistor R24 is bypassed. This allows
To the gate of the field effect transistor Q2, a voltage divided by the resistors R21, R22, and R23, which is lower than that during normal lighting, is applied, and the on-resistance of the field effect transistor Q2 and the capacitors C7 and C8 follow. Capacitor C11
The base current is supplied to the base of the transistor Q1 according to the combined capacity of the transistor Q1 and the inverter circuit 4 outputs in a state suitable for preheating, the fluorescent lamp FL1 does not start, and the filament FL
1a, FL1b, FL2a, and FL2b are preheated at appropriate voltages.

Thereafter, when the capacitor C31 is charged and the transistor Q8 is turned off, the resistor R24 is connected and the resistor R21 is connected.
, R22, R23, and R24 of the resistor R23 and the voltage divided by the resistor R24 are applied, and the capacitor C7 and the capacitor C7
According to the combined capacitance of C8 and the capacitor C11 according to the on-resistance of the field-effect transistor Q2, a base current is supplied to the base of the transistor Q1, and the base current of the transistor Q1 is increased as compared with the time of preheating. Therefore, a relatively high voltage is induced in the secondary winding Tr2b of the inverter transformer Tr2, and the fluorescent lamps FL1, FL2 are started. In this state, the capacitor C17 is not sufficiently charged, the programmable unijunction transistor Q3 does not turn on, the light-emitting diode LED1 does not emit light, and the phototransistor Q5 maintains the off state. Is not performed.

When the fluorescent lamps FL1 and FL2 are turned on, the base current of the transistor Q1 is suppressed as compared with that at the time of starting, so that an appropriate voltage is applied to the fluorescent lamps FL1 and FL2.

When the fluorescent lamps FL1 and FL2 enter a half-wave discharge state at the end of life or the like, the voltage of the capacitor C12 increases, the voltage of the capacitor C16 increases, and the programmable unijunction transistor Q3 turns on. When the light emitting diode LED1 emits light and the phototransistor Q5 is turned on, the transistor Q6 is turned on, and the transistor Q7 and the field effect transistor Q2 are turned off.
The base current of the transistor Q1 further decreases, the output of the inverter circuit 4 decreases or stops, and the fluorescent lamp FL1
, FL2 goes out.

On the other hand, the filaments FL1a, FL1b, FL2a, FL2b of the fluorescent lamps FL1, FL2 are emitterless, and so on.
When the voltage between both ends of the fluorescent lamps FL1 and FL2 increases, the voltages of the capacitors C18 and C19 increase, and the programmable unijunction transistor Q3 is turned on. Similarly, the fluorescent lamps FL1 and FL2 are turned off.

[0039]

According to the discharge lamp lighting device of the present invention, the control circuit controls the variable capacitance circuit using a variable capacitor and a capacitor having a reduced capacity in the preheating state in which the preheating is performed by the preheating circuit. At the time of lighting, the variable capacitance circuit is controlled using a variable capacitor and a capacitor with a larger capacity than the preheated state, and in the end-of-life state detected by the end-of-life detection circuit, the variable capacitance circuit is controlled using a capacitor. Also, the output of the inverter circuit at the end of life can be reduced as compared with that at the time of preheating without complicating the circuit configuration, so that preheating can be appropriately performed at the time of preheating and the output can be prevented from becoming unnecessarily large at the end of life.

[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 conventional discharge lamp lighting device.

[Explanation of symbols]

 4 Inverter circuit 7 Variable capacitance circuit 8 Variable capacitor 11 End-of-life detection circuit 12 Preheating circuit 15 Control circuit C8 Capacitor FL1, FL2 Fluorescent lamp FL1a, FL1b, FL2a, FL2b filament Q1 transistor as discharge lamp

Claims (1)

[Claims] An inverter circuit for operating a transistor to light a discharge lamp having a filament, a variable capacitor, and a drive circuit for controlling the transistor by changing the capacitance of the variable capacitor circuit A preheating circuit for detecting a predetermined time after starting the discharge lamp; an end-of-life detection circuit for detecting the end of life of the discharge lamp; and a variable capacity circuit having a capacity in a preheating state in which the preheating circuit preheats. The variable capacity circuit was controlled using a variable capacitor and a capacitor having a larger capacity than the preheated state during normal lighting, and the end of life was detected by the end of life detection circuit. In the end of life state, the variable capacitance circuit is controlled using a capacitor. The discharge lamp lighting apparatus characterized by comprising a road.