JP3010789B2 - Discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for lighting a discharge lamp at a high frequency by an inverter device.

[0002]

2. Description of the Related Art A circuit diagram of a conventional discharge lamp lighting device is shown in FIG. This circuit is a self-excited series resonance type inverter, and switching transistors Q ₁ , Q _{2 in} which diodes D ₁ , D ₂ are connected in anti-parallel to a DC power source E, respectively.
₂ of the series circuit are connected, the transistors Q _1,
Resistors R ₂ and R ₃ are inserted in series with the emitter of Q ₂ , respectively. These resistors R ₂ and R ₃ are negative feedback resistors commonly called emitter resistors, and are used to prevent the transistors Q ₁ and Q ₂ from being overdriven. Between the positive terminal of the transistor Q ₂ collector and the DC power source E is driven through the transformer T ₁ of the primary winding and the inductor L ₁ and capacitor C _2, the power supply-side terminals of the filament lamp F ₁ is connected Have been. Between the discharge lamp F ₁ of non-power-side terminals of the filament, the parallel circuit of a capacitor C ₄ and a resistor R ₇ is connected. Capacitor C ₄ and inductor L ₁
Constitutes a series resonance circuit. Capacitor C ₂ is a coupling capacitor for DC component cutting (inversion capacitor), the capacitance is sufficiently large as compared with the capacitor C _4, hardly contributes to the resonance. Drive transformer T ₁
Has two secondary windings. One of the secondary winding is connected between the base and emitter of the transistor Q ₁ via the resistor R _4, R _2. Also, the other secondary winding has a resistor R
₅ and R ₃ are connected between the base and the emitter of the transistor Q ₂ . Thus, a self-excited inverter device is configured.

[0003] Next, the resistance R ₁ and a capacitor C ₁ and a trigger element Q ₃ are constitute a starting circuit. At power on,
When the voltage of the DC power source E is increased, the capacitor C ₁ is charged through the resistor R _1. When the voltage of the capacitor C ₁ reaches the breakover voltage of the trigger element Q _3, conducts the trigger element Q _3, it is intended for activating the inverter apparatus by flowing a base current to the transistor Q ₂ in the charge of the capacitor C _1. After starting the inverter,
Since the charge in the capacitor C ₁ through the diode D ₁ is discharged, the starting circuit is to stop the activation pulse generation operation.

Next, a control circuit for stopping oscillation in the event of an abnormality
Will be described. Transistor Q _TwoEmitter resistance R
_ThreeIs input to the abnormality detection circuit 1. Conden
Sa C _TwoAnd discharge lamp F₁Is connected to the resistor R₁₃And R₁₅
, And is input to the reset circuit 3.
The output of the abnormality detection circuit 1 is the set input of the holding circuit 2.
The output of the reset circuit 3 is the reset input of the holding circuit 2.
It has been. The output of the holding circuit 2 is a resistor R₂₀Through
Transistor Q₉Is entered in the base. Transis
TA Q₉The collector and the emitter of the transistor Q_TwoNo
And the negative terminal of the DC power supply E.

The operating power supply of this control circuit is a capacitor C
Obtained from ₀ . That is, the capacitor C ₀ is charged from the DC power supply E via the resistor dropper R ₀ , and the voltage is regulated by the overvoltage preventing zener diode ZD.
_A low DC voltage is obtained at both ends of ₀ . This DC voltage is supplied as an operation power supply voltage to a control circuit including the abnormality detection circuit 1, the holding circuit 2, and the reset circuit 3.

The operation of the circuit shown in FIG. 3 will be briefly described below. After the power is turned on, the transistor Q ₂
When an ON signal is input to the DC power source E, the capacitors C ₂ ,
A resonance current flows through C ₄ , inductor L ₁ , drive transformer T ₁ , transistor Q ₂ and resistor R _3, and transistors Q ₁ and Q ₂ are turned on by drive transformer T ₁ by self-excitation.
The turning off is repeated, and the inverter starts oscillating. Further, the discharge lamp F ₁ is the end of life or the like, abnormal current flowing through the resistor R ₃ is detected by the abnormality detection circuit 1, the signal is input to the holding circuit 2, the transistor Q ₉ is turned on,
The oscillation of the inverter device stops. When oscillation stops,
Abnormality detection signal disappears, but the transistor Q ₉ is required to continue on, it is necessary to hold circuit 2. Further, when replacing the lamp F ₁ in order to reset the holding circuit 2, it is necessary to reset circuit 3. Further, in order to perform the above control, the resistance R ₀ and the capacitor C
_A control power supply composed of ₀ and a zener diode ZD is required. In this circuit, although the abnormality detection is detected by the resistor R _3, it may use other detection methods.

In this conventional example, a control power supply is required,
There is a problem that the power loss of the dropper resistor R ₀ for producing the control power supply is large, and the control circuit becomes complicated because the holding circuit 2 and the reset circuit 3 are provided.

In order to solve such a problem, a discharge lamp lighting device as shown in FIG. 4 has been proposed (see Japanese Patent Publication No. 3-12439). Hereinafter, the circuit configuration and operation will be described. An AC power supply (220 V /
50 Hz) and a DC connected to the rectifier G and having a charging reactor L, a charging diode D, charging switches T1, T2 and a charging capacitor C.
A DC converter forms a DC power supply having a controllable DC voltage. The charging capacitor C is connected to a series circuit composed of two transistors of an inverter that are alternately conductive. The transistor T3 adjacent to the charging diode D is hereinafter referred to as a secondary transistor, and the other transistor T1 is referred to as a primary transistor. A load circuit composed of a series circuit of a discharge lamp E and a series resonance circuit capacitor C2, and a series circuit of a reactor L2, an oscillation capacitor C1, and a primary winding L30 of a saturable transformer is connected in parallel with the secondary transistor T3. The capacitor C2 of the circuit is placed between the two preheating electrodes of the discharge lamp E,
One electrode is directly connected to the charging capacitor C.

The saturable transformer has two secondary windings L31,
L32 and a cutoff winding L33. Secondary winding L31,
L32 is a primary transistor T1, a secondary transistor T
In the third control circuit, both of these transistors are connected so that their conduction is alternately controlled during the reversal magnetization time of the saturable transformer. In this case, the saturable transformer is configured such that the determined operating frequency of the inverter is slightly above the resonant frequency of the series resonant circuit. By doing so, a gap is created between successive conduction control pulses, so that simultaneous conduction of the primary transistor and the secondary transistor is avoided, and hence a short circuit of the voltage at the charging capacitor C is avoided. Feedback current diodes D1, D2 are provided in parallel with each of the transistors for conduction during simultaneous blocking of both transistors. During the conduction time of the primary transistor T1, the voltage of the charging capacitor C is applied to the load circuit, and the oscillation capacitor C
1 is charged with the polarity shown. After the primary transistor T1 enters the blocking state and until the secondary transistor T3 conducts, current flows through the load circuit and is driven by the reactor L2 of the series resonance circuit to provide the feedback current diode D2.
Continue to flow through 2. Then the secondary transistor T3
Until it is again in the blocking state, the oscillating capacitor C1 discharges via the secondary transistor T3 and the load circuit. Thereafter, the load current continues to flow in the same direction via the charging capacitor C and the feedback current diode D1 until a new conduction of the primary transistor T1.

Energy taken from the charging capacitor C during the operation of the inverter is supplied from the rectifier G to the charging capacitor C via the charging reactor L and the charging diode D. In the circuit of FIG. 4, for this purpose, the primary transistor T1 and the charging thyristor T2 are connected in series to form a charging switch, and the charging reactor L is connected in parallel to the rectifier G via this charging switch.

The charging thyristor T2 is controlled in synchronization with the switching operation of the inverter. For this purpose, the control section of this charging thyristor T2 is connected in parallel to a delay capacitor C6 via a trigger diode D9, which on the one hand is connected in parallel to a secondary transistor T3 via a discharge diode D8, Further, it is connected to a control power supply via a primary transistor T1, an adjustable discharge resistor R1, and a backflow prevention diode D7. The control power supply comprises a control transistor T5 and a storage capacitor C5 provided in parallel with the control transistor T5.
5 together with a diode D5 and a voltage dividing capacitor C7 constitute a voltage divider in parallel with the primary transistor T1.

The energy stored in the starting capacitor C8 is applied to the control section of the primary transistor T1 via the trigger diode D13, so that the voltage of the starting capacitor C8 reaches a value at which the primary transistor T1 conducts. Only when this occurs, the vibration inverter starts operating, and then the DC-DC converter starts operating.
For this purpose, the starting capacitor C8 is connected on the one hand to the resistors R2, R2.
4 and the charging capacitor C via one electrode of the lamp E
And on the other hand is connected in parallel to the switching section of the primary transistor T1 via a diode D10. After applying the AC power supply voltage to the rectifier G, the charging capacitor C is charged via the charging reactor L and the charging diode D, and accordingly the starting capacitor C8 is also charged until the primary transistor T1 is turned on. Then, at the same time, the starting capacitor C8 is discharged again via the diode D10, so that this starting circuit can no longer be involved during the periodic oscillation of the inverter.

When the discharge lamp E is in a state where it cannot be started continuously, that is, when the useless start is repeatedly performed, one cut-off state and one operation state are set in order to cut off the inverter. A bistable switching element in the form of a stop thyristor T4 is provided, a control circuit and a holding circuit. The switching section of the stop thyristor T4 is connected in parallel to the cut-off winding L33 of the saturable transformer via diodes D11 and D12, and is connected in parallel to the starting capacitor C8 via a resistor R2. The switching section of the stop thyristor T4 is further inserted in a holding circuit in series with the electrode of the discharge lamp adjacent to the charging capacitor C and the series resistor R4.

The breaking winding L33 also has an RC element R3,
A control circuit with C9 is connected in parallel via a diode D11 and this RC element is connected in parallel via a trigger diode D14 to the control section of the stop thyristor T4. The function and configuration of this circuit are as follows. The amplitude of the current flowing through the load circuit having the discharge lamp and detected by the cut-off winding L33 indicates that the lamp is lit when the lamp is not lit (resonant state). On the basis that it is significantly larger than in the case where it is present (the damping state of the resonant circuit). After the useless starting times that can be given in advance by the configuration, the capacitor C9 is charged so that the stop thyristor T4 fires via the trigger diode D14 and short-circuits the cutoff winding L33. As a result, there is no control voltage for the transistor of the inverter, and the operation of the inverter is shut off. However, neither a normal lighting operation nor a normal lamp current will cause such an interruption. This is because, in this case, the voltage at the capacitor C9 does not reach the value required to make the trigger diode D14 conductive.

For the synchronous control of the DC-DC converter depending on the square wave voltage in the switch of the inverter,
The DC-DC converter is automatically shut down with the inverter and is turned on again after starting the inverter.

The inverter remains shut off until the holding circuit of the stop thyristor T4 is shut off and thus the stop thyristor T4 can again enter the blocking state. For this purpose, for example, the AC power supply voltage can be cut off. However, there are very often interruptions resulting from the replacement of defective lamps that can be performed without interruption of the mains voltage. Since the current circuit of the starting capacitor C8 is also supplied via the lamp electrodes, the inverter automatically starts oscillating again after setting a new lamp.

With this circuit configuration, the oscillation of the inverter device can be stopped by using a thyristor at the time of abnormality such as at the end of the lamp life without restarting the lamp, and the lamp can be restarted at the time of lamp replacement without the need of a control power supply. To summarize the features of this conventional example, a starting loop is formed through one filament of the lamp, the drive transformer is short-circuited by using a thyristor at the time of abnormality, and the holding current of the thyristor is obtained from the starting resistance, so that at the time of abnormality, The oscillation stop is maintained, the holding current is cut when the lamp is replaced, and the inverter device is started again when the discharge lamp is mounted again.

In this conventional example, the starting circuit is connected via one filament of the lamp. If the preheating electrode e1 in FIG. 4 is disconnected, the oscillation does not start even if the power is turned on. When the electrode e2 is disconnected,
The start circuit operates, and the start pulse is always given. In the case of the circuit configuration of the parallel lighting system as shown in FIG. 5, when the preheating electrodes e1 and e2 are disconnected,
When the preheating electrode e1 is disconnected, the oscillation stops and the preheating electrode e2
If the lamp E is broken, two phenomena occur when the lamp E 'is normal and the lamp E' is turned on by one lighting. Even when the lamp is mounted, when the preheating electrode e2 is inserted after the preheating electrode e1 is inserted first, when the preheating electrode e2 is inserted, a start pulse has already been generated, and there is a possibility that one lamp is turned on. When inserting the preheating electrode e2, an excessive resonance current flows, and stress is applied to the switching element.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a discharge lamp lighting device for lighting a discharge lamp at high frequency by an inverter device. It is an object of the present invention to realize a circuit for holding the state in which the oscillation of the inverter device is stopped in the event of an abnormality such as the end of life of the inverter device with a simple configuration, and to obtain low power loss and reliable operation.

[0020]

According to the present invention, in order to solve the above-mentioned problems, as shown in FIG. 1, a capacitor C _{1 is provided in} a starting circuit of an inverter device for lighting a discharge lamp.
And a time constant circuit of a resistor R ₁ and a trigger element Q ₃ that breaks over with the voltage of the capacitor C ₁ , wherein a circuit for stopping and holding the oscillation of the inverter device at the time of abnormality including at least the end of life of the discharge lamp. the connected across the capacitor C _1, it is characterized in that a means for resetting said hold circuit when replacing the lamp.

[0021]

In the present invention, attention is focused on a starting circuit of an inverter device using CR time constant circuits C ₁ and R ₁ and a trigger element Q _3. Oscillation of the inverter device is stopped at both ends of a capacitor C ₁ of the starting circuit. Since the holding circuit is connected, no new power loss occurs, and the inverter circuit can be surely restarted by the starting circuit when the discharge lamp is replaced.

[0022]

FIG. 1 is a circuit diagram of an embodiment of the present invention. Less than
Hereinafter, the circuit configuration will be described. Positive end of DC power supply E
The child is transistor Q₁Connected to the collector. G
Transistor Q₁Of the resistor R_TwoTransit through
Star Q_TwoConnected to the collector. Transistor Q
_TwoOf the resistor R_ThreeTo the negative terminal of DC power supply E
It is connected. A diode D is connected to both ends of the DC power supply E.
_Two, D_ThreeAre connected in reverse polarity,
Code D_Two, D_ThreeIs connected to transistor Q_TwoCollector
It is connected to the. Transistor Q_TwoThe collectors
Drive transformer T₁Primary winding n₁And inductor L₁Through
And discharge lamp F₁Of the first filament f₁₁Is connected at one end
And discharge lamp F₁Of the second filament f₁₂One end of the
Capacitor C_TwoConnected to the negative terminal of the DC power source E
I have. Discharge lamp F₁Filament f₁₁, F₁₂At each other end
Is the capacitor C_FourAnd resistance R₇Are connected in parallel.
Drive transformer T₁Primary winding n₁And inductor L₁Contact
The continuation point is the resistance R₆Connected to the positive terminal of DC power supply E
And the inductor L_TwoThrough the discharge lamp F_TwoFirst
Filament f_{twenty one}Of the discharge lamp F_TwoNo.
2 filament f_{twenty two}One end of the capacitor C_ThreeThrough
It is connected to the negative terminal of DC power supply E. Discharge lamp F_TwoNo
Filament f_{twenty one}, F_{twenty two}The other end of the capacitor C_FiveAnd
Anti-R₈Are connected in parallel. Drive transformer T₁No.
1 secondary winding n_TwoIs the resistance R_Four, R _TwoTransit through
Star Q₁Connected between the base and the emitter of
Secondary winding n_ThreeIs the resistance R_Five, R_ThreeThrough Transis
TA Q_TwoIs connected between the base and the emitter of Second
Secondary winding n_ThreeSecondary winding n wound in the opposite polarity to_Fourof
One end is connected to the negative terminal of the DC power supply E, and the other end is a diode.
Do D_FourThyristor Q via_FourConnected to the anode of
I have.

Capacitor C_TwoAt both ends of the resistor R₁₃, R
₁₅Are connected in parallel, and the connection point is
Diode D₆Are connected. Similarly,
Capacitor C_ThreeAt both ends of the resistor R₁₄, R₁₆Series circuit
Are connected in parallel, and the connection point is a diode D
_FiveAre connected. Diode D_Five, D ₆
Each anode of the transistor Q₈Connected to the base of
ing. Transistor Q₈Collector / emitter
Capacitor C₁Are connected in parallel at both ends.

Next, the resistor R ₁ , the capacitor C ₁ and the trigger element Q ₃ constitute a starting circuit. At power on,
When the voltage of the DC power source E is increased, the capacitor C ₁ is charged through the resistor R _1. When the voltage of the capacitor C ₁ reaches the breakover voltage of the trigger element Q _3, conducts the trigger element Q _3, it is intended for activating the inverter apparatus by flowing a base current to the transistor Q ₂ in the charge of the capacitor C _1. After starting the inverter,
Since the charge in the capacitor C ₁ through the diode D ₁ is discharged, the starting circuit is to stop the activation pulse generation operation. Also, even when the inverter is stopped,
When the transistor Q ₈ is conductive, because the capacitor C ₁ is not charged, the starting circuit does not generate a start pulse.

The connection point of the discharge lamp F ₁ of filaments f ₁₁ and the inductor L ₁ is connected to the negative terminal of the DC power source E through a resistor R _9, R ₁₀ and capacitor C _6. Similarly,
Connection point of the discharge lamp F ₂ of the filament f ₂₁ and the inductor L ₂ is connected to the negative terminal of the DC power source E via a capacitor C ₇ resistors R _11, R _12. The connection point of the resistors R _9, R _10, one end of the resistor R ₁₉ is connected, the base of the emitter and the transistor Q7 of the transistor Q ₆ is connected to the connection point of the resistors R _11, R ₁₂ is , the other end of the resistor R ₁₉ is connected, the base of the emitter and the transistor Q ₆ of the transistor Q ₇ is connected. The collectors of the transistors Q ₆ and Q ₇ are connected to one end of a capacitor C ₈ via an anode and a cathode of a diode D ₈ , and the other end of the capacitor C ₈ is connected to a negative terminal of a DC power supply E. . One end of the capacitor C _8, the resistor R
It is connected to the gate of the thyristor Q ₄ through ₁₈ and the trigger element Q _5. Between the gate and cathode of the thyristor Q ₄ the resistor R ₁₇ are connected in parallel. Capacitor C ₁ and the connection point of the resistor R ₁ in the starting circuit through the anode-cathode of the diode D _7, is connected to the anode of the thyristor Q _4.

In the above circuit configuration, the presence or absence of a discharge lamp is detected.
The output circuit is connected to the DC power supply E and the discharge lamp F₁about,
Resistance R₆, Inductor L₁, Filament f₁₁, Resistance R
₇, Filament f₁₂, Resistance R₁₃, R₁₅DC current circuit
And the discharge lamp F _TwoFor the resistance R₆,
Inductor L_Two, Filament f_{twenty one}, Resistance R₈, Fira
Ment f_{twenty two}, Resistance R₁₄, R₁₆Consists of a DC current circuit
And each discharge lamp F₁, F_TwoEach filament f₁₁, F
₁₂, F_{twenty one}, F_{twenty two}Can be detected. Ma
In addition, the abnormality detection circuit for the end of life of the discharge lamp
Is a method of detecting the voltage difference between the capacitors C
₈Is charged. As the inverter oscillation stop circuit,
Drive transformer T₁Secondary winding n_FourFrom diode D_FourTo
Thyristor Q through_FourAre connected, and
Star Q_FourAnode is diode D ₇Starting circuit through
Capacitor C₁It is connected to the.

The operation of this embodiment will be described below. (A) First, the case where the discharge lamp is normal will be described. The discharge lamps F ₁ and F ₂ have the same wattage. When the power is turned on, to try to charge the capacitor C ₁ via the resistor R _1. However, the transistor Q in the capacitor C _1
8 are connected in parallel, and the divided voltages of the resistors R ₁₃ and R ₁₅ and the resistors R ₁₄ and R ₁₆ that determine the base potential of the transistor Q ₈ are determined by the charging voltages of the capacitors C ₂ and C _3. Since the voltage rise is slower than the time constant of the resistor R ₁ and the capacitor C ₁ , the charging potential of the capacitor C ₁ is eventually charged according to the time constant of the discharge lamp presence / absence detection circuit. The divided voltages of the resistors R ₁₃ and R ₁₅ are supplied to the DC power supply E by a resistor R ₆ , an inductor L ₁ , and resistors R ₇ , R ₁₃ and R _15.
To be determined by the time constant of the capacitor C _2. Further, the divided voltage of the resistors R ₁₄ and R ₁₆ is supplied to the DC power source E by a resistor R
₆ , the inductor L ₂ , the resistors R ₈ , R ₁₄ , R ₁₆ and the time constant of the capacitor C ₃ . Therefore, the resistors R ₁₃ and R ₁₅
And by setting higher than the breakover voltage of the R _14, triggering a divided voltage of the R ₁₆ element Q _3, a trigger element Q ₃ it is always turned on. If the on trigger element Q _3, enters the ON signal to the transistor Q _2, the capacitor C
_A series resonance current flows through the capacitors C ₄ and C ₅ and the inductors L ₁ and L ₂ using the power sources ₂ and C ₃ as power sources, and starts oscillating. If the discharge lamps F ₁ and F ₂ are lit normally,
The difference in lamp voltage without almost no voltage is charged in the capacitor C _8. Thus, the thyristor Q ₄ is also off.

[0028] In this case if the (B) filament breakage or one filament is out, in the present embodiment, when deviates in one filament, when the discharge lamp F _1, the DC power source E, resistors R _6,
The DC current circuit of the inductor L ₁ , the filament f ₁₁ , the resistor R ₇ , the filament f ₁₂ , and the resistors R ₁₃ and R ₁₄ is cut off. In the case of the discharge lamp F ₁₂ , the DC power source E, the resistor R ₆ , the inductor L ₂ , the filament f _21, resistors R _8, since the direct current circuit of the filament f _22, resistors R _14, R ₁₆ is shut off, the resistor R _13, R ₁₅ or R _14, either of the divided voltage of the R ₁₆ is 0, transistor Q ₈ is turned on, the charge in the capacitor C ₁ for activation is not accumulated, therefore, since the starting pulse is not generated, the inverter device is not activated.

[0029] (C) a normal discharge lamp is end of life, if after the oscillation stop, the inverter device when replacing oscillates in a normal state, the transistor Q ₂ is turned on and off at a high frequency, the diode D ₁
Since the by far the charge in the capacitor C ₁ via the voltage of the capacitor C ₁ is becomes almost 0V. Next, when one of the discharge lamps reaches the end of its life, it enters a half-wave discharge state, causing a difference in the waveform of the voltage across the discharge lamp. The voltage difference charges the capacitor C ₈ via the diode D ₈ . When the voltage of the capacitor C ₈ is equal to or greater than the certain, diac Q ₅ is turned on. When the diac Q ₅ is turned on, the thyristor Q
₄ turns on and the secondary winding n ₄ of the drive transformer T ₁
There are short-circuited through the diode D _4, the oscillation of the inverter is stopped. When the oscillation stops, the abnormality detection signal disappears, the diac Q ₅ is turned off, at that time, the
Since the holding current flows through the thyristor Q ₄ via a resistor R ₁ and a diode D ₇ from the DC power source E, the thyristor Q ₄ are held in the conductive state. Thus, the capacitor C ₁ for activation not accumulate charge for starting, because the starting pulse is not generated, the inverter maintains the oscillation stop state.

Then, the discharge lamp is replaced. When the discharge lamp is removed, the DC current circuit for detecting the presence or absence of the discharge lamp is cut off, so that the divided voltage of the resistors R ₁₃ and R ₁₅ or R ₁₄ and R ₁₆ decreases, and the diode D ₅ or D ₆ Through the transistor Q
_A current flows between the emitter and the base of the transistor ₈ , and the transistor Q8 is turned on. In this case, it is cut holding current of the thyristor Q ₄ is turned off thyristor Q ₄ is, the secondary winding n ₄ of the drive transformer T ₁ is because it is open, the oscillation stop of the inverter is reset. However, in this case, since the discharge lamp is out, it remains transistor Q ₈ is on, the voltage of the capacitor C ₁ for starting does not rise. After that, only when a normal discharge lamp is inserted,
Voltage of the capacitor C ₁ for starting is reached breakover voltage of the trigger element Q _3, giving an activation pulse signal for turning on the transistor Q _2, an oscillation of the inverter device is started.

FIG. 2 is a circuit diagram of another embodiment of the present invention.
You. In this embodiment, a 200 V AC power supply e is connected to a full-wave rectifier.
Rectified by DB, inductor L_TenAnd transistor Q_Tenas well as
Diode D_TenWith a step-up chopper circuit
And a DC voltage of 400 V₉Fill in
It is charging. The control circuit S is a transistor Q_TenOn Oh
To control the power. Transistor Q_TenWhen on
Inductor L_TenThe energy stored in
TA Q_TenWhen the diode D is off_TenThrough smooth condensate
Sa C₉Is charged. Smoothing capacitor C₉Charged
400V DC is the transistor Q₁, Q_TwoSeries circuit
Has been applied. Each transistor Q₁, Q _TwoEmitter of
Has a resistance R_Two, R_ThreeAre inserted in series.
You. Transistor Q_TwoCollector and smoothing capacitor C₉
Between the positive terminals of
Capacitor C_TwoAnd the drive transformer T₁Primary winding and inductor
Kuta L ₁Through the discharge lamp F₁The power side of the filament
Terminal is connected. Discharge lamp F₁Non-filament
Capacitor C on power supply side terminal_FourAnd resistance R₇Are connected in parallel
Have been. Capacitor C_FourAnd inductor L₁Is series resonance
Make up the circuit. Drive transformer T₁Is the inductor L
₁And capacitor C_FourA little higher than the natural vibration frequency of
It is designed to oscillate at the wave number. Startup circuit is rectified
The input of the subsequent voltage is₁And capacitor C₁, Da
Iod D₁, Trigger element Q_ThreeAnd transistor Q₁₁
It is composed of Transistor Q₁₁Is the presence or absence of a discharge lamp
Is detected and turned on / off. Discharge lamp detection circuit
Is the resistance R₇, R_{twenty one}, R_{twenty three}, R_{twenty four}And diode D₁₁In
Is switched on when a discharge lamp is inserted.
Star Q₁₁Is turned on. The abnormality detection circuit
Sa C₁₁, C₁₂, Resistance R_{twenty five}, R ₂₆, Diode D₁₂, D₁₃
And capacitor C₁₃And the output is a thyristor
Q_FourConnected to the oscillation stop circuit.

Hereinafter, the operation of this embodiment will be described.
First, it is assumed that the boost type chopper circuit operates after a certain period of time after the power is turned on. Thus, the DC voltage is obtained in the smoothing capacitor C _9. Next, operations when the discharge lamp is normal, when the wire is disconnected, and when the lamp is remounted will be described.

(A) When the discharge lamp is normal When the power is turned on, the smoothing capacitor C₉Directly obtained
From the power supply E to the capacitor C_TwoThrough the diode D
₁₁, Resistance R_{twenty three}, R_{twenty four}The current flows through the path. Normal discharge
If the lamp is inserted, the potential at the point X becomes almost E × (R_{twenty three}
+ R_{twenty four}) / (R _{twenty one}+ R₇+ R_{twenty three}+ R_{twenty four}) Charged
You. At this time, the resistance R_{twenty four}Depending on the voltage
Jista Q₁₂Turns on and the resistance R_{twenty two}Current
Transistor Q ₁₁Turns on. This activates the startup circuit.
It becomes possible to work and the resistance R₁Through the capacitor C₁Charge the
I do. Capacitor C₁Is the trigger element Q_ThreeBlur
When the output voltage exceeds the_TwoLaunch on
A pulse signal is applied, and the transistor Q_TwoTurns on,
The inverter starts oscillating. If the discharge lamp is normal
In the case, the capacitor C of the abnormality detection circuit₁₃Voltage is set low.
And the Zener diode ZD₁Does not turn on.
Therefore, thyristor Q_FourIs also off.

(B) When the discharge lamp is broken or one of the filaments is disconnected. In this case, the DC power source E supplies the resistor R ₂₁ and the drive transformer T _1.
, The inductor L ₁ , one filament of the discharge lamp F ₁ , the resistor R ₇ , and the DC current circuit passing through the other filament of the discharge lamp F ₁ are cut off, so that the capacitor C ₂
When the power is turned on, the potential at the point X becomes 0V. Therefore, the divided voltage of the resistors R _23, R ₂₄ also becomes 0V, the transistor Q ₁₂ is turned off, the transistor Q ₁₁ is also turned off. Therefore, blocking the charging path of the capacitor C ₁ for activation, it does not initiate the oscillation of the inverter device.

(C) When the discharge lamp reaches the end of its life and the discharge lamp is replaced after oscillation stops When the discharge lamp reaches the end of its life from the normal lighting state, the discharge lamp enters a half-wave discharge state. peak-to-peak value of the voltage across increases, the potential of the capacitor C ₁₃ of the abnormality detection circuit is high, the zener diode ZD ₁ is turned on. When the Zener diode ZD ₁ is turned on, the thyristor Q ₄ is turned on, the charge stored in the capacitor C _13, the resistor R _28, the thyristor Q _4, through the base-emitter of the transistor Q ₉ is discharged, the transistor Q ₉ There turned on to clamp the base of the transistor Q _2, to stop the oscillation of the inverter device. In this case, the discharge time constant of the capacitor C _13, so is set sufficiently longer than the switching period of the transistor Q _1, Q ₂ of the main circuit of the inverter device periods which can turn on the transistor Q _9, the inverter device Oscillation stops. In addition,
Resistor R ₂₇ which is inserted in series with the cathode side of the thyristor Q ₄ of the oscillation stop circuit is set to a larger impedance to the base of the transistor Q _9.

Thyristor Q_FourOnce turned on,
From the power supply, the transistor Q₁₁, Resistance R₁, Diode D
₇, Thyristor Q_Four, Resistance R₂₇Current also flows in the path of
This current becomes the holding current, and the thyristor Q_FourTurns on
to continue. Thyristor Q_FourKeeps the ON state in the above current path.
Hold, the capacitor C of the starting circuit₁The voltage of the trigger
ー Element Q_ThreeJust enough to break over
No, the startup circuit does not operate. Therefore, the oscillation stop state is maintained.
Be held. Next, remove the discharge lamp for replacement.
Sensor C_TwoIs charged to the voltage of the DC power source E,
The potential at point X for light detection becomes 0 V, and the transistor
Q₁₂Is turned off, and the transistor Q of the starting circuit is turned off.₁₁Turn off
You. Therefore, the resistance R₁No holding current flowing through
Thyristor Q_FourTurns off. Next, a new discharge lamp
Is inserted, the discharge lamp described in (a) above becomes normal.
As in the case, the potential at the point X is almost E × (R_{twenty three}+ R_{twenty four}) /
(R _{twenty one}+ R₇+ R_{twenty three}+ R_{twenty four}) And the resistance R_{twenty three},
R_{twenty four}Of the transistor Q₁₂But
Transistor Q₁₁Turns on and the startup circuit operates
Oscillation is started and the light is turned on.

[0037] In this embodiment, since using the chopper circuit of step-up is to increase the DC voltage of the smoothing capacitor C _9, the starting circuit to reduce power losses is connected to the output end of the rectifier DB. Further, in order to at oscillation stop also continues to flow holding current, the load is very light state connects the capacitor C ₁₀ of the capacity enough to sufficiently smooth the output end of the rectifier DB.

As shown in the embodiment of FIG. 1, a plurality of discharge lamps may be provided. Even in such a case, the circuit for detecting the presence / absence of the discharge lamp does not become complicated and can be simply constituted by an OR circuit. Oscillation can be started after all the filaments are attached, especially in the case of multi-lamp lighting.

[0039]

In the discharge lamp lighting device according to the first aspect, the oscillation stop and holding circuit of the inverter device is connected to both ends of the capacitor of the starting circuit, so that the oscillation stops in the event of an abnormality without newly providing a special power supply. The state can be maintained, and the operation can be reliably restarted by the operation of the starting circuit when the discharge lamp is replaced.

In the discharge lamp lighting device according to the second aspect, since the general-purpose starting circuit including the resistor, the capacitor, the trigger element, and the diode is used, the function of the present invention can be realized without largely changing the design of the existing circuit. This has the effect.

In the discharge lamp lighting device according to the third aspect, a thyristor is connected in parallel to both ends of a starting capacitor as a holding circuit, and a holding current is made to flow using the resistance of the starting circuit. Even without it, the holding function can be realized,
This has the effect of preventing an increase in power loss.

In the discharge lamp lighting device according to the fourth aspect, since the switching element for interrupting the holding current of the thyristor is connected in parallel or series with the capacitor of the starting circuit, the function of holding the thyristor easily by opening and closing the switching element. There is an effect that it can be reset.

In the discharge lamp lighting device according to the fifth aspect, if at least one filament of one or a plurality of discharge lamps is disconnected, the oscillation of the inverter device can be stopped. There is an effect that reliability is increased without stress being applied.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention.

FIG. 2 is a circuit diagram of another embodiment of the present invention.

FIG. 3 is a circuit diagram of a conventional example.

FIG. 4 is a circuit diagram of another conventional example.

FIG. 5 is a circuit diagram of another conventional example.

[Explanation of symbols]

E DC power supply Q ₁ transistor Q ₂ transistor Q ₃ trigger element Q ₄ thyristor F ₁ discharge lamp F ₂ discharge lamp R ₁ resistor C ₁ capacitor D ₁ diode

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yukio Yamanaka 1048 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Works Co., Ltd. (56) References JP-A-4-132194 (JP, A) JP-A-1-157099 JP-A-64-3999 (JP, A) JP-A-62-76296 (JP, A) JP-A-61-29097 (JP, A) JP-A-62-163292 (JP, A) Kaihei 3-127495 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05B 41/24 H02M 7/537

Claims (5)

(57) [Claims] 1. A discharge lamp lighting device having a time constant circuit of a resistor and a capacitor in a starting circuit of an inverter device for lighting the discharge lamp and a trigger element that breaks over with a voltage of the capacitor, including at least the end of life of the discharge lamp. A discharge lamp lighting device, characterized in that a circuit for stopping and holding oscillation of an inverter device in the event of an abnormality is connected to both ends of the capacitor, and means for resetting the holding circuit when replacing the discharge lamp is provided. 2. The inverter device according to claim 1, wherein a series circuit of two switching elements that are alternately turned on and off is connected to a DC power supply, and the starting circuit includes a series circuit of a resistor and a capacitor connected in parallel to the DC power supply. Connected and configured by connecting a voltage-responsive trigger element between the connection point of the resistor and the capacitor and the control electrode of one of the switching elements, so that the charge of the capacitor is discharged when the one of the switching elements is turned on. The discharge lamp lighting device according to claim 1, wherein the capacitor is connected in parallel between the main electrodes of the one switching element via a diode. 3. The circuit for stopping and holding the oscillation of the inverter device comprises a thyristor connected in parallel to both ends of the capacitor, and the resistance of the starting circuit constitutes a holding current supply path of the thyristor. The discharge lamp lighting device according to claim 1, wherein 4. The discharge lamp lighting device according to claim 3, wherein a switching element for interrupting a holding current of said thyristor is connected in parallel or series with a capacitor of said starting circuit. 5. The apparatus according to claim 1, further comprising means for detecting the presence or absence of the discharge lamp based on the presence or absence of a DC current circuit passing from the DC power supply through each filament of the discharge lamp.
The discharge lamp lighting device as described in the above.