JPH10294192A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which can achieve proper outputs whether a fluorescent lamp is being started or in trouble. SOLUTION: During preheating, a voltage is applied to the gate of a field effect transistor Q13, and although an apparent resistance value between the drain and source of the field effect transistor Q13 is rather high, a capacitor C38 is connected in parallel with a capacitor C39 to preheat the filaments FLa, FLb of a fluorescent lamp FL. During startup and lighting, a gate voltage is applied to the field effect transistor Q13, and the capacitor C38 is connected in parallel with the capacitor C39 to start and light the fluorescent lamp FL. If the fluorescent lamp FL is removed or in a half-wave discharge state due to the end of its life, etc., the lamp is driven in either case by a base current set in accordance with only the capacity of the capacitor C39, and a sufficiently lower voltage than that used during preheating is induced in the secondary winding Tr2b of an inverter transformer Tr2 to ensure safe operation.

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 which outputs an appropriate output at the time of abnormality, at the time of preheating of the discharge lamp, and at the time of starting.

[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, the input side of a full-wave rectifier circuit 1 of a bridge of diodes D1, D2, D3 and D4 is connected to a commercial AC power supply e.
Are connected to smoothing capacitors C1 and C2.

A half-bridge type inverter circuit 2 is connected to both ends of these capacitors C1 and C2.
This inverter circuit 2 has a transistor Q1 and a transistor Q2. A reflux diode D5 is connected in anti-parallel to the transistor Q1, a reflux diode D6 is connected in anti-parallel to the transistor Q2, and a capacitor C3 is connected in parallel to the diode D6. A resistor that constitutes a timer circuit at power-on, in parallel with the series circuit of capacitors C1 and C2
A series circuit of R1, R2, R3, R4 and a capacitor C4 is connected. The connection point of the resistor R4 and the capacitor C4 is connected to a transistor Q1 and a transistor Q2 via a diode D7.
Connected to the connection point.

Further, a control circuit 3 is connected to each base of the transistor Q1 and the transistor Q2.

Further, a transistor Q1 and a transistor
The connection point of Q2 is connected to the connection point of the capacitors C1 and C2 via the primary winding Tr2a of the inverter transformer Tr2 via the detection winding CT1a of the current transformer CT1.

Further, it is connected to one end of filaments FLa and FLb of the fluorescent lamp FL via a load abnormality detecting circuit 4 for detecting half-wave discharge, and a starting capacitor C11 is provided between the other ends of these filaments FLa and FLb. The filament FLa is connected to a condenser C12 for preheating, and the filament FLb is connected to a condenser C13 for preheating.

In the load abnormality detecting circuit 4, a capacitor C14 is connected between the primary winding Tr2a of the inverter transformer Tr2 and the filament FLb, and a series circuit of a resistor R5 and a resistor R6 is connected in parallel to the capacitor C14. ing. Further, a series circuit of a diode D8 and a resistor R7 is connected in parallel with the capacitor C13, a series circuit of a resistor R8 and a capacitor C15 is connected to the series circuit of the diode D8 and the resistor R7, and a resistor R9 is connected to the capacitor C15. Are connected in parallel. The connection point between the resistor R8 and the capacitor C15 is connected to the base of the transistor Q3, and the resistor R9 is connected between the emitter and the base of the transistor Q3. The collector of the transistor Q3 is connected to the base of the transistor Q4 via the resistor R11, and the emitter and the base of the transistor Q4 are connected to the resistor R12.

Further, a capacitor C21, a capacitor C22 and a load abnormality detecting circuit 4 such as a lamp life are connected in series to the secondary winding Tr2b of the inverter transformer Tr2.
A diode D11 is connected in parallel to the capacitor C22, and a series circuit of the diode D12 and the capacitor C23 is connected to the diode D11.
Is connected in parallel with the resistor R14, a series circuit of a capacitor C24 and a diode D13 is connected in parallel with the resistor R14, and a resistor R1 is connected in parallel with the diode D13.
5 is connected.

Further, a capacitor C24 and a diode D1
The connection point 3 is connected to the base of the transistor Q5,
The emitter of this transistor Q5 is a load abnormality detection circuit 4.
The collector is connected to the secondary winding Tr2b of the inverter transformer Tr2 via the resistor R16 and the diode D14, and the connection point of the resistor R16 and the diode D14 is connected to the diode D15.
And is connected to the load abnormality detection circuit 4 via. In addition, a resistor is connected between the collector and emitter of transistor Q5.
R17, resistor R18, Zener diode ZD1 and resistor R19
The capacitor C25 is connected in parallel with the resistor R18, and the connection point of the resistor R18, the capacitor C25 and the zener diode ZD1 is connected to the gate of the programmable unijunction transistor Q6. The anode of the unijunction transistor Q6 is connected to the connection point of the resistor R17 and the capacitor C25, the emitter and collector of the transistor Q4 are connected between the cathode and the gate, and the cathode is connected to the load abnormality detection circuit 4 via the light emitting diode LED1. A connection detection circuit 5 for detecting whether or not the fluorescent lamp FL is mounted is formed by these components.

On the other hand, between the output terminals of the full-wave rectifier circuit 1,
A series circuit of resistor R21 and capacitor C31 is connected,
The resistor R22 is connected in parallel with the capacitor C31, and the light emitting diode LED1 is connected in parallel with the capacitor C31.
A phototransistor Q7, which is photocoupled, is connected to the transistor Q8. The emitter of the transistor Q8 is connected to a connection point between the resistor R21 and the capacitor C31.
Is connected to the negative electrode of the full-wave rectifier circuit 1 via a Zener diode ZD2, and the collector is connected via a capacitor C32.

The collector of the transistor Q8 is connected to the resistor R2.
3 and a diode D21, connected to the base of the transistor Q11.A capacitor C33 and a resistor R24 are connected in parallel between the base and the emitter of the transistor Q11, and between the collector and the emitter of the transistor Q11.
A capacitor C35 is connected via a capacitor C34, a diode D22 is connected in parallel with the capacitor C35, and a connection point of the capacitor C35 and the capacitor C35 is connected to a transistor via a control winding CT1b of a current transformer CT1 and a resistor R25. The transistor Q1 is connected to a base, and a series circuit of a diode D23 and a resistor R26 is connected between the base and the emitter of the transistor Q1.

Further, in parallel with the capacitor C32,
A series circuit of a resistor R27, a resistor R28 and a resistor R29 is connected, and the resistor R27 is connected via a resistor R30 to a collector of a transistor Q12. An emitter of the transistor Q12 is connected to a negative electrode of the full-wave rectifier circuit 1 via a resistor R31. It is connected. The base of the transistor Q12 is connected to the positive electrode of the full-wave rectifier circuit 1 via the resistors R32 and R33, and is connected to the negative electrode of the full-wave rectifier circuit 1 via the diode D22 and the resistor R34. Diode D22
And a capacitor C3 in parallel with the series circuit of resistor R33.
6 are connected in parallel. In addition, transistor Q12
Is a full-wave rectifier circuit 1 via a capacitor C37.
Connected to the gate of a field effect transistor Q13 via a resistor R35. The source of the field effect transistor Q13 is connected to the negative electrode of the full-wave rectifier circuit 1. The drain is connected to a capacitor C38. The control winding CT1c of the transformer CT1 and the resistor R36 are connected to the base of the transistor Q2. The capacitor C35 and the control winding CT1c are connected to the negative electrode of the full-wave rectifier circuit 1 via the capacitor C39 and the diode D24. Diode D25 and resistor R3
7 is connected, a series circuit of a diode D25 and a resistor R36 is connected between the base and the emitter of the transistor Q2, and the connection point of the resistor R1 and the capacitor C8 is
It is connected to the connection point of the control winding CT1c and the resistor R36 via a series circuit of the diac Q14 and the resistor R38.

The AC voltage of the commercial AC power supply e is full-wave rectified by the full-wave rectifier circuit 1 and a DC voltage is supplied to the inverter circuit 2 by the capacitors C1 and C2. Also,
When the capacitor C4 is charged, the diac Q14 conducts and turns on the transistor Q2. Also, the capacitor C31 is gradually charged by the time set by the time constant of the resistor R1 and the capacitor C31, and until the capacitor C31 is charged to a predetermined voltage, the zener diode ZD2 does not turn on and the capacitor C32 is charged. Since the transistor Q11 does not turn on, the capacitor C34 remains open. Further, since the capacitor C32 is not charged, the transistor Q12 also keeps the off state, and the field effect transistor Q13 turns off.
Also maintain the open state. Therefore, the transistor Q1 is driven by the base current set by the capacitance of the capacitor C35, the transistor Q2 is driven by the base current set by the capacitance of the capacitor C39, and the relatively low voltage is applied to the secondary winding Tr2b of the inverter transformer Tr2. Induced fluorescent lamp
The filaments FLa and FLb of FL are preheated, respectively.

Thereafter, when the capacitor C31 is charged and the zener diode ZD2 is turned on, the transistor Q8 is turned on, the capacitor C32 is charged, the capacitor C33 is also charged, and the transistor Q11 is turned on, and the capacitor is connected in parallel with the capacitor C35. When C34 is connected and transistor Q8 turns on, field-effect transistor Q1
The gate voltage is applied to 3 and the capacitor C38 is connected in parallel with the capacitor C39. Therefore, transistor Q1 is driven by the base current set by the capacitance of capacitor C34 and capacitor C35, and transistor Q2 is driven by the base current set by the capacitance of capacitor C38 and capacitor C39, respectively, and the secondary winding Tr2b of inverter transformer Tr2 is driven. A relatively high voltage is induced in the fluorescent lamp
FL starts. In this state, the capacitor C24 is not sufficiently charged, the transistor Q5 short-circuits both ends of the zener diode ZD1, the thyristor Q6 does not turn on, and the light-emitting diode LED1 does not emit light, so the phototransistor Q7 also turns off. Since the state is maintained, no protection operation is performed.

When the fluorescent lamp FL is turned on, the voltage between the base and the emitter of the transistor Q12 decreases, and the conduction impedance of the transistor Q12 changes more than when the starting voltage is generated. Since the current is suppressed as compared with the time of starting, an appropriate voltage is applied to the fluorescent lamp FL.

If the fluorescent lamp FL is detached or the fluorescent lamp FL is in a half-wave discharge state at the end of its life, the voltage of the capacitor C15 increases, and a base current flows to the base of the transistor Q3, so that the transistor Q3
Turns on and the transistor Q4 turns on when the light emitting diode
When LED1 emits light and transistor Q7 turns on, zener diode ZD2 turns off and the potential at both ends of capacitor C32 disappears, so that the state is the same as in preheating.Transistor Q1 is at the base current set by the capacity of capacitor C35. The transistor Q2 is driven by a base current set by the capacitance of the capacitor C39, and a relatively low voltage is induced between the output terminals.

[0018]

However, in the case of the configuration shown in FIG. 4, when the fluorescent lamp FL is preheated, and when an abnormality is detected by the load abnormality detecting circuit 4 or the mounting detecting circuit 5, the structure is not limited to that shown in FIG. , Driven by the base current set by the capacitors C35 and C39, and in any case, the output of the inverter circuit 2 is set equal. In other words, the output of the inverter circuit 2 is set to be substantially equal both when the fluorescent lamp FL is preheated and when it is abnormal. Therefore, if the output of the inverter circuit 2 is set to an output suitable for preheating the fluorescent lamp FL, for example, the life of the fluorescent lamp FL At the end of the period, the output may be too high, and stress may be applied to each part of the inverter circuit 2. If the output is set to an appropriate value at the time of an abnormality, the filaments FLa and FLb cannot be sufficiently preheated when the fluorescent lamp FL is preheated. There is a problem that the starting failure of the lamp FL or the single life of the fluorescent lamp FL may occur.

SUMMARY OF THE INVENTION 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 appropriately setting the output when the fluorescent lamp is started or when it is abnormal.

[0020]

SUMMARY OF THE INVENTION A discharge lamp lighting device according to the present invention includes a discharge lamp lighting circuit capable of preheating and lighting a discharge lamp and variable output, an abnormality detecting means for detecting an abnormality, and an abnormality detecting means for detecting the abnormality. Is detected, the output of the discharge lamp lighting circuit is different at the time of preheating of the discharge lamp and the start of the discharge lamp, respectively, when an abnormality is detected by the abnormality detection means, at the time of preheating of the discharge lamp, Control means for increasing the output of the discharge lamp lighting circuit in the order of starting the discharge lamp. Then, the control means increases the output of the discharge lamp lighting circuit in the order of when the abnormality is detected by the abnormality detection means, when the discharge lamp is preheated, and when the discharge lamp is started. If an abnormality is detected by the detection means, the output is reduced sufficiently to prevent stress on each part, etc., and by obtaining sufficient output necessary for preheating at the time of preheating, the discharge lamp is reliably Prevents shortening of service life by preheating.

[0021]

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. Parts corresponding to those of the conventional example shown in FIG.

In the discharge lamp lighting device shown in FIG. 1, a filter circuit 11 is connected to a commercial AC power supply e, and this filter circuit 11 is connected to the commercial AC power supply e via a fuse F, a constant voltage element Z1, a capacitor C41, Transformer Tr3, inductor L11
, Capacitor C42, constant voltage element Z2 and capacitor C43
This filter circuit 11 includes a diode D
1, the input side of the full-wave rectifier circuit 1 of the bridge of D2, D3 and D4 is connected, and the output side of the full-wave rectifier circuit 1 is connected to smoothing capacitors C1 and C2.

Further, an inverter circuit 2 as a half-bridge type discharge lamp lighting circuit is connected to both ends of the capacitors C1 and C2, and the inverter circuit 2 has a transistor Q1 and a transistor Q2. And
Diode D5 for reflux in anti-parallel to transistor Q1
A diode D6 for reflux is connected in anti-parallel to the transistor Q2, a capacitor C3 is connected in parallel to the diode D6, and a power supply is connected in parallel to the series circuit of the capacitors C1 and C2. A series circuit of a resistor R1 and a capacitor C4 constituting a timer circuit at the time of turning on is connected, and a connection point between the resistor R1 and the capacitor C4 is connected to a connection point between the transistor Q1 and the transistor Q2 via a diode D7.

Further, a control circuit 3 as control means is connected to the base of each of the transistors Q1 and Q2.

The transistor Q1 and the transistor
The connection point of Q2 is connected to the connection point of the capacitors C1 and C2 via the primary winding Tr2a of the inverter transformer Tr2 via the detection winding CT1a of the current transformer CT1.

Further, it is connected to one end of filaments FLa and FLb of a fluorescent lamp FL as a discharge lamp via a load abnormality detecting circuit 4 for detecting a half-wave discharge, and a starter is connected between the other ends of the filaments FLa and FLb. Is connected to the filament FLa, and a preheating capacitor C12 is connected to the filament FLa.
Is connected, and the filament FLb is connected to a capacitor for preheating.
C13 is connected.

In the load abnormality detection circuit 4, a capacitor C14 is connected between the primary winding Tr2a of the inverter transformer Tr2 and the filament FLb, and a series circuit of a resistor R5 and a resistor R6 is connected in parallel to the capacitor C14. ing. Further, a series circuit of a diode D8 and a resistor R7 is connected in parallel with the capacitor C13, a series circuit of a resistor R8 and a capacitor C15 is connected to the series circuit of the diode D8 and the resistor R7, and a resistor R9 is connected to the capacitor C15. Are connected in parallel. The connection point between the resistor R8 and the capacitor C15 is connected to the base of the transistor Q3, and the resistor R9 is connected between the emitter and the base of the transistor Q3. The collector of the transistor Q3 is connected to the base of the transistor Q4 via the resistor R11, and the emitter and the base of the transistor Q4 are connected to the resistor R12.

Further, a capacitor C21, a capacitor C22 and a load abnormality detecting circuit 4 such as a lamp life are connected in series to the secondary winding Tr2b of the inverter transformer Tr2.
A diode D11 is connected in parallel to the capacitor C22, and a series circuit of the diode D12 and the capacitor C23 is connected to the diode D11.
Is connected in parallel with the resistor R14, a series circuit of a capacitor C24 and a diode D13 is connected in parallel with the resistor R14, and a resistor R1 is connected in parallel with the diode D13.
5 is connected.

The capacitor C24 and the diode D1
The connection point 3 is connected to the base of the transistor Q5,
The emitter of this transistor Q5 is a load abnormality detection circuit 4.
The collector is connected to the secondary winding Tr2b of the inverter transformer Tr2 via the resistor R16 and the diode D14, and the connection point of the resistor R16 and the diode D14 is connected to the diode D15.
And is connected to the load abnormality detection circuit 4 via. In addition, a resistor is connected between the collector and emitter of transistor Q5.
R17, resistor R18, Zener diode ZD1 and resistor R19
The capacitor C25 is connected in parallel with the resistor R18, and the connection point of the resistor R18, the capacitor C25 and the zener diode ZD1 is connected to the gate of the programmable unijunction transistor Q6. The anode of the unijunction transistor Q6 is connected to the connection point of the resistor R17 and the capacitor C25, the emitter and collector of the transistor Q4 are connected between the cathode and the gate, and the cathode is connected to the load abnormality detection circuit 4 via the light emitting diode LED1. A connection detection circuit 5 is formed as abnormality detection means for detecting whether or not the fluorescent lamp FL is mounted.

On the other hand, between the output terminals of the full-wave rectifier circuit 1,
A series circuit of resistor R21 and capacitor C31 is connected,
The resistor R22 is connected in parallel with the capacitor C31, and the light emitting diode LED1 is connected in parallel with the capacitor C31.
A phototransistor Q7, which is photocoupled, is connected to the transistor Q8. The emitter of the transistor Q8 is connected to a connection point between the resistor R21 and the capacitor C31.
Is connected to the negative electrode of the full-wave rectifier circuit 1 via a Zener diode ZD2, and the collector is connected via a capacitor C32.

A resistor R41 is connected between the emitter and the collector of the transistor Q8. The collector is connected to the base of the transistor Q11 via a resistor R23 and a diode D21. A capacitor is connected between the base and the emitter of the transistor Q11. C33 and a resistor R24 are connected in parallel, a capacitor C35 is connected between the collector and the emitter of the transistor Q11 via a capacitor C34, and a diode D22 is connected in parallel with the capacitor C35. The connection point of
The transistor Q1 is connected to the base of the transistor Q1 via the control winding CT1b of the current transformer CT1 and the resistor R25.
Diode D23 and resistor R26 between base and emitter
Are connected in series.

Further, in parallel with the capacitor C32,
The series circuit of resistor R28 and resistor R29 is connected and resistor R2
8 and the connection point of the resistor R29 are connected to the collector of the transistor Q12 via the resistor R30.
Is connected to the negative electrode of the full-wave rectifier circuit 1 via a resistor R31. The base of the transistor Q12 is connected to the positive electrode of the full-wave rectifier circuit 1 via the resistors R32 and R33, and is connected to the negative electrode of the full-wave rectifier circuit 1 via the diode D22 and the resistor R34. A capacitor C36 is connected in parallel with the series circuit of the diode D22 and the resistor R33. Further, the collector of the transistor Q12 is connected to the negative electrode of the full-wave rectifier circuit 1 via the capacitor C37 and to the gate of the field effect transistor Q13 via the resistor R35. Is connected to the negative electrode of the full-wave rectifier circuit 1, and the drain is connected to the capacitor C38.
Connected to the base of transistor Q2 via the control winding CT1c of the current transformer CT1 and the resistor R36.
C38 and the control winding CT1c are connected to the negative electrode of the full-wave rectifier circuit 1 via the capacitor C39 and the diode D24, and a diode D2 is connected between the base and the emitter of the transistor Q2.
5 and resistor R37 are connected in series.
A series circuit of a diode D25 and a resistor R36 is connected between the base and emitter of Q2.
The connection point of C8 is connected to the connection point of the control winding CT1c and the resistor R36 via a series circuit of the diac Q14 and the resistor R38.

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

First, the AC voltage of the commercial AC power source e is full-wave rectified by the full-wave rectifier circuit 1, and the capacitor C1 and the capacitor
A DC voltage is supplied to the inverter circuit 2 by C2. When the capacitor C4 is charged, the diac Q14 conducts and turns on the transistor Q2. The time set by the time constant of resistor R1 and capacitor C31
C31 is gradually charged, and during preheating until the capacitor C31 is charged and reaches a predetermined voltage, the Zener diode ZD2 does not turn on, so the transistor Q8 maintains the off state,
The capacitor C32 is charged via the resistor R41, and a gate voltage is applied to the field effect transistor Q11.
Since the field effect transistor Q11 is slightly turned on, the apparent resistance value between the drain and the source of the field effect transistor Q11 is slightly high, but the capacitor C34 is connected to the capacitor C3.
5 is connected in parallel. In addition, transistor Q8
Is off, the current flows through the resistor R41.
The transistor Q12 also has a high impedance between the collector and emitter, but turns on
A voltage is applied to the gate of Q13, and although the apparent resistance between the drain and source of this field effect transistor Q13 is slightly higher, the capacitor C38 is connected in parallel with the capacitor C39.

Therefore, transistor Q1 is a capacitor
Base current set by C34 and capacitor C35,
The capacitor C2 is driven by the base currents set by the capacitors C38 and C39, respectively, and a slightly higher voltage is induced in the secondary winding Tr2b of the inverter transformer Tr2, and the filaments FLa and FLb of the fluorescent lamp FL are preheated, respectively. .

Thereafter, when starting and lighting, the capacitor C31
Is charged and the Zener diode ZD2 turns on, the transistor Q8 turns on, short-circuits the resistor R41, and the capacitor C3
2 is charged, the capacitor C33 is also charged, the transistor Q11 is turned on, the capacitor C34 is connected in parallel with the capacitor C35, and the transistor Q8 is turned on, so that the gate voltage is applied to the field effect transistor Q13. , Capacitor C3 in parallel with capacitor C39
8 is connected. Therefore, transistor Q1 is driven by the base current set by the capacitance of capacitor C34 and capacitor C35, and transistor Q2 is driven by the base current set by the capacitance of capacitor C38 and capacitor C39, respectively, and the secondary winding Tr2b of inverter transformer Tr2 is driven. , A relatively high voltage is induced to start the fluorescent lamp FL. In this state, the capacitor C24 is not sufficiently charged, and the transistor Q5 short-circuits both ends of the zener diode ZD1, so that the programmable unijunction transistor Q6 does not turn on, and the light emitting diode LED1 does not emit light. Since the phototransistor Q7 also maintains the off state, no protection operation is performed.

When the fluorescent lamp FL is turned on, the voltage between the base and the emitter of the transistor Q12 decreases, so that the conduction impedance of the transistor Q12 changes more than when the starting voltage is generated. Since the current is suppressed as compared with the time of starting, an appropriate voltage is applied to the fluorescent lamp FL.

If the fluorescent lamp FL is detached or the fluorescent lamp FL is in a half-wave discharge state at the end of its life, the voltage of the capacitor C15 increases, and a base current flows to the base of the transistor Q3, thereby causing the transistor Q3 to flow. Q3
Turns on and the transistor Q4 turns on when the light emitting diode
When LED1 emits light and the phototransistor Q7 turns on, both ends of the capacitor C31 are short-circuited. Then, as the potential of the capacitor C32 decreases, the gate voltage of the field effect transistor Q11 decreases or stops, the capacitor C34 is opened, the transistor Q12 is also turned off, and the field effect transistor Q13 is turned off. Also maintain the open state. Therefore, the transistor Q1 is driven by the base current set by the capacitance of the capacitor C35, and the transistor Q2 is driven by the base current set by the capacitance of the capacitor C39.
A sufficiently low voltage is induced in the secondary winding Tr2b of Tr2 as compared with the time of preheating, and safe operation is performed.

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 Zener diode ZD3 is connected in series to a capacitor C32 instead of the Zener diode ZD2 and the transistor Q8.

The basic operation is the same as that of the configuration shown in FIG. 1. However, during preheating until the capacitor C31 is charged, the field effect transistor Q11 and the field effect transistor Q12 are relatively connected via the resistor R41. A low voltage gate voltage is applied to put the output of the inverter circuit 2 in a preheated state, and when starting and lighting after the capacitor C31 is charged, the Zener diode ZD3 short-circuits the resistor R41, and the field-effect transistor Q11 Field effect transistor Q12
, A gate voltage having a high voltage value is applied, and the output of the inverter circuit 2 is started and turned on.

When the fluorescent lamp FL is removed or when the fluorescent lamp FL enters a half-wave discharge state at the end of its life, the phototransistor Q7 short-circuits both ends of the capacitor C31, and the field effect transistor Q11 and the field effect transistor The gate voltage of the transistor Q12 is stopped, and the output of the inverter circuit 2 is sufficiently lower than that at the time of preheating, and the operation is safe.

In each of the above embodiments, the lamp non-attachment is detected by detecting the voltage between the filaments. However, the same effect can be obtained by detecting the lamp by any other method. .

Another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 1 in that a smoothing capacitor C51 is connected to the full-wave rectifier circuit 1, and a partial smoothing circuit 12 is connected in parallel to the capacitor C51. This partial smoothing circuit 12 is a parallel circuit of a capacitor C52 and a resistor R51, and an inductor L15
And the series circuit of the diode D31 are connected, and the connection point of the inductor L15 and the diode D31 is connected to the diode.
D32 is connected.

Further, a one-piece inverter circuit 2 is connected as a discharge lamp lighting circuit. This inverter circuit 2 is composed of a parallel circuit of a primary winding Tr2a of an inverter transformer Tr2 and a resonance capacitor C53, and a switching transistor. The collector and emitter of Q11 are connected in parallel, and the base of transistor Q11 is connected
The transistor Q11 is connected to the positive terminal of the full-wave rectifier circuit 1 via a series circuit of R53.
A series circuit of a diode D33 and a resistor R54 is connected. Further, a series circuit of a capacitor C54 and a control winding CT1b of a current transformer CT1 is connected between the base and the emitter of the transistor Q11, and a series circuit of a diode D34 and a diode D35 is connected in parallel with the capacitor C54. The connection point between D34 and diode D35 is connected to the base of transistor Q11 via diode D36. Also, in parallel with the capacitor C54, the capacitor C55 and the field-effect transistor Q1
3 series circuit is connected.

Further, a resistor R55 is connected to the secondary winding Tr2b of the inverter transformer Tr2, a series circuit of a resistor R56 and a resistor R57 is connected in parallel with the resistor R5, and a current is connected in series with the capacitor C14. Transformer CT2 detection winding
CT2b is connected.

A parallel circuit of a resistor R55, a light emitting diode LED2 and a capacitor C56 is connected in series with the transistor Q5.

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 1, smoothed by the capacitor C 51 and the partial smoothing circuit 12, and supplied to the inverter circuit 2. Further, a base current for starting is supplied via the resistors R52 and R53, and the transistor Q11 is turned on. Then, based on the parallel resonance circuit 14 and the control winding CT1b of the lamp current detected by the detection winding CT1a, the transistor Q11 opens and closes.

Also, the capacitor C31 is gradually charged in the time set by the time constant of the resistor R21 and the capacitor C31, and the zener diode ZD2 does not turn on during preheating until the capacitor C31 is charged and reaches a predetermined voltage. As a result, the transistor Q8 maintains the off state, the capacitor C32 is charged via the resistor R41, and a gate voltage is applied to the field effect transistor Q13.This field effect transistor Q13 is slightly turned on, so that the field effect transistor Q1 is turned on.
Although the apparent resistance between the drain and source 3 is slightly higher, the capacitor C54 is connected in parallel with the capacitor C55.

Therefore, the transistor Q11 is driven by the base current set by the capacitors C54 and C55, and a slightly higher voltage is induced in the secondary winding Tr2b of the inverter transformer Tr2, and the filament Q of the fluorescent lamp FL
FLa and FLb are each preheated.

Thereafter, when starting and lighting, the capacitor C31
Is charged and the Zener diode ZD2 turns on, the transistor Q8 turns on, short-circuits the resistor R41, and the capacitor C3
2 is charged, the capacitor C33 is also charged, the transistor Q13 is turned on, and the capacitor C54 is connected in parallel with the capacitor C55. Therefore, transistor Q11
Is driven by the base current set by the capacitance of the capacitors C54 and C55, a relatively high voltage is induced in the secondary winding Tr2b of the inverter transformer Tr2, and the fluorescent lamp FL starts. In this state, the capacitor C24
Is not sufficiently charged, and transistor Q5 shorts across Zener diode ZD1, resulting in a programmable
Since the unijunction transistor Q6 does not turn on, the light emitting diode LED1 does not emit light, and the phototransistor Q7 maintains the off state, no protection operation is performed.

When the fluorescent lamp FL is turned on, the voltage between the base and the emitter of the transistor Q12 decreases, and the conduction impedance of the transistor Q12 changes more than when the starting voltage is generated. Since the current is suppressed as compared with the time of starting, an appropriate voltage is applied to the fluorescent lamp FL.

When the fluorescent lamp FL is removed, the secondary winding Tr2b of the inverter transformer Tr2 is opened, and the output of the inverter circuit 2 is stopped.

Further, when the fluorescent lamp FL enters a half-wave discharge state at the end of life or the like, the voltage of the capacitor C23 increases, and when the programmable unijunction transistor Q6 is turned on, the light emitting diode LED1 emits light,
Turning on the phototransistor Q7 short-circuits both ends of the capacitor C31. Then, when the potential of the capacitor C32 decreases, the gate voltage of the field effect transistor Q13 stops, the capacitor C54 is opened, and the transistor Q11 is driven by the base current set by the capacitance of the capacitor C55, and the current of the inverter transformer Tr2 is reduced. Secondary winding
A sufficiently low voltage is induced in Tr2b even when preheating,
Operate safely.

In any of the above embodiments, the output was varied by controlling the attachment and detachment of the capacitor.
The same effect can be obtained even if the output is varied by controlling the reset current of the transistor.

[0058]

According to the discharge lamp lighting device of the present invention, the control means controls the output of the discharge lamp lighting circuit when an abnormality is detected by the abnormality detection means, when the discharge lamp is preheated, and when the discharge lamp is started. The output of the discharge lamp lighting circuit is increased in this order, so if an abnormality is detected by the abnormality detection means, the output can be sufficiently reduced to prevent stress on each part, etc., and necessary for preheating at the time of preheating By obtaining a sufficient output, it is possible to reliably prevent the discharge lamp from being preheated and shorten its 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 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]

 2 Inverter circuit as discharge lamp lighting circuit 3 Control circuit as control means 5 Mounting detection circuit as abnormality detection means FL Fluorescent lamp as discharge lamp

Claims (1)

[Claims] A discharge lamp lighting circuit capable of preheating and lighting the discharge lamp to change the output; abnormality detection means for detecting an abnormality; when an abnormality is detected by the abnormality detection means, when the discharge lamp is preheated; The output of the discharge lamp lighting circuit is varied at the start of the discharge lamp, and when the abnormality is detected by the abnormality detecting means, the discharge lamp is preheated, and the discharge lamp is started in the order of the discharge lamp lighting circuit. Control means for increasing the output of the discharge lamp.