JP2567435B2 - Discharge lamp lighting device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a two-stone push-pull inverter type discharge lamp lighting device that performs pre-heating and dimming.

[Background technology]

As shown in FIG. 3, the conventional discharge lamp lighting device converts the power supply voltage of the AC power supply E into a voltage which is phase-controlled by the power control device I of the phase control type using the triac Th, and further the rectifier circuit II. Full-wave rectification is applied to the two-stone push-pull type inverter circuit VI through the smoothing circuit IV and the parallel circuit of the bypass switch element SCR that has the pre-heating voltage dividing resistor R ₁ and the pre-heating timer circuit III. The 2-stone push-pull inverter circuit VI is oscillated at a high frequency of 40 KHz, and the high-frequency power obtained from the 2-stone push-pull inverter circuit VI is supplied to the discharge lamp LA to heat and light the filament of the discharge lamp LA. It was supposed to be done.

The preceding preheating timer circuit III holds the bypass switching element SCR in the OFF state for a fixed time (1 to 3 seconds) after the power is turned on, and the smoothing circuit IV is connected through the preceding preheating voltage dividing resistor R ₁ during this period. And power is supplied to the two-stone push-pull type inverter circuit VI, and after a lapse of a certain time after power-on, the smoothing circuit
The power is supplied directly to the IV and the two-stone push-pull type inverter circuit VI.

The smoothing circuit IV is configured by combining _two capacitors C ₁ and C ₂ and three diodes D ₁ , D ₂ and D _3, and two capacitors when charged by the output voltage of the rectifier circuit II. It is charged in series through C ₁ , C ₂ and diode D ₁ , and its capacitor voltage is charged to almost half of the peak value of the output voltage of rectifier circuit II, and the output voltage of rectifier circuit II drops below the peak value. When approaching the valley point and reaching almost half of the peak value, the charges of those capacitors C ₁ and C ₂ are discharged through the diodes D ₂ and D ₃ , and power is supplied to the two-stone push-pull inverter circuit VI. As shown in FIGS. (A) and (b), the potential of the output of the power adjustment device I during the idle period is compensated by smoothing the capacitors C ₁ and C ₂ .

In addition, FIG. 5 (a) shows the triac of the power adjusting device I.
The waveform of the voltage across the smoothing circuit IV when Th is fully conductive is shown, and FIG. 5 (b) shows the waveform of the same part when the triac Th of the power regulator I is in a conductive state of about 90 degrees. .

 The operation will be described here.

When the AC power supply is turned on with the output of the power regulator I set to the maximum (all lighting), the power supply voltage that is full-wave rectified by the rectifier circuit II via the power regulator I causes the preheating partial pressure. It is smoothed by the capacitors C ₁ and C ₂ of the smoothing circuit IV via the resistor R ₁ and is applied to the two-stone push-pull inverter circuit VI with a lower voltage.

At the same time, the base current is applied to the transistors Q ₃ and Q ₄ by the voltage between the base-emitter of the first resistor R ₂ and the third transistor Q ₂ and the second and third resistors R ₃ and R _4. Supplied.

Due to a slight imbalance in the circuit, a collector current flows in either one of the first and second transistors Q ₃ and Q ₄ , causing the primary winding N ₁ of the oscillation transformer OT ₁ to have either N ₁₁ or N ₁₂ winding. An electric current flows.

In the initial state when the AC power source E is applied, the base power source capacitor C ₃ is not charged, and therefore the first power source capacitor C ₃ is
Only the current is obtained through the resistor R ₂ of the transistor Q ₃ , Q
The base current of ₄ is a very low current.

Next, a current flows through either the primary winding N ₁₁ or N ₁₂ of the oscillation transformer OT ₁ so that the base drive power supply winding
A voltage is also induced in N ₂ and the feedback winding N ₃ , and the base power supply capacitor C ₃ is charged via the diode D ₄ .

Due to the induced voltage in the feedback winding N ₃ , the ON operation of the transistors Q ₃ and Q ₄ is inverted, and the two-stone push-pull inverter circuit VI
Starts, and the oscillation transformer OT ₁ resonates with the resonance capacitor C ₄ and starts oscillation at a high frequency of about 40 KHz.

At the same time, the filament heating winding N _{5 of} the oscillating transformer OT ₁ ,
High-frequency voltage is also induced in each N ₆ to preheat the filamenta of the discharge lamp LA.

At this time, since a low voltage is supplied to the input side of the two-stone push-pull inverter circuit VI through the preheating voltage dividing resistor R ₁ , the output voltage of the secondary winding N ₄ is at the discharge lamp LA. The discharge lamp LA is in a non-lighting state and is in a non-lighting state.

When the base power supply capacitor C ₃ is charged, the transistor Q is connected to the base power supply capacitor C ₃ via the collector-emitter of the third transistor Q ₂ and the second and third resistors R ₃ and R _{4. Since a} sufficient base current is supplied to ₃ and Q ₄ , the 2-stone push-pull inverter circuit VI performs stable oscillation operation.

Next, the timer circuit III operates after a certain period of time (a period in which the filament of the discharge lamp is sufficiently preheated, usually about 1 to 3 seconds), and the bypass switch element SCR.
Turns on and two stone push-pull type inverter circuit VI
The full voltage of full wave rectification is applied to the oscillation transformer OT ₁
The secondary voltage of becomes high, and the discharge lamp LA lights up.

The inductance L has a high inductance with respect to the high frequency of about 40 KHz, and makes the input current to the two-stone push-pull inverter circuit VI close to a flat current.

However, in this conventional discharge lamp lighting device, when the AC power source E is turned on in a dimming state in which the conduction phase of the power adjusting device I is delayed, the power adjusting device I has a pause section,
The voltage across the smoothing circuit IV has a longer valley-filled section and a lower effective value than in the case of full lighting as shown in FIG. 5 (b) [FIG. 5 (a)].

In addition, in the state immediately after the AC power supply E is turned on, the base power supply capacitor C ₃ is not charged, and therefore only the current through the first resistor R ₂ is obtained at the time of startup, and the transistor C ₃
The base currents of Q ₃ and Q ₄ are very small currents.

Thus, at the time of starting the two-stone push-pull inverter circuit VI by applying a low voltage through the preceding preheating voltage dividing resistor R ₁ during the preceding preheating, the transistor
The base currents of Q ₃ and Q ₄ are the first resistor R ₂ , the base-emitter of the third transistor Q ₂ , and the second and third resistors R ₃ and R 4.
Although attempts to flow through the _4, in fact, the current through the second resistor R ₃ as shown in Fig. 4 I ₃ includes a base current I ₃₁ flowing in the first transistor Q ₃ feedback winding a base current I ₃₂ flowing through the line N ₃ to the second transistor Q _4, the current I ₄ through the third resistor R _4, the second transistor Q feedback winding N and the base current I ₄₁ flowing in the ₄ There is a problem that the base current I ₄₂ flowing to the first transistor Q ₃ via ₃ is shunted, and the base currents of the transistors Q ₃ and Q ₄ are insufficient to cause the two-stone push-pull inverter circuit VI to start. .

This is because once the 2-stone push-pull type inverter circuit VI starts, the base drive power supply winding N _{2 of the} oscillation transformer OT ₁
By the output of, the base power supply capacitor C ₃
It is charged through D ₄ , and using this base power supply capacitor C ₃ as the base power supply, the collector of the third transistor Q ₂
Transistor with sufficient base current through the emitter
Since supplied to Q _3, Q _4, early in the meantime, the preheating timer circuit III has been a problem that occurs while operating.

In order to improve this problem, it is conceivable to reduce the resistance value of the first resistor R ₂ , but because the circuit voltage is high, the power consumption becomes large and the size of the resistor becomes large. There was a problem such as a large loss.

Further, it is considered that the first and second transistors Q _3, Q ₄ using large transistor amplification factor, in normal use unnecessary, there is a problem that the unit price becomes high.

[Object of the Invention]

An object of the present invention is to provide a discharge lamp lighting device capable of reliably starting and heating and lighting a discharge lamp even in a deep dimming state.

[Disclosure of Invention]

In the discharge lamp lighting device of the present invention, a rectifier circuit is connected to an AC power source via a phase control type power adjusting device, and a parallel circuit of a preheating voltage dividing resistor and a bypass switch element is provided on the output side of the rectifier circuit. A pre-heating timer circuit for connecting the smoothing circuit and turning on the bypass switching element for a certain period of time after the power is turned on, and supplying power to the two-stone push-pull inverter circuit from both ends of the smoothing circuit to discharge the discharge lamp. I try to turn on the high frequency.

The above-mentioned two-stone push-pull type inverter circuit has NPN type first and second transistors and a resonance capacitor connected in push-pull connection to the primary winding of the oscillation transformer in parallel, and the middle point of the primary winding of the oscillation transformer is connected. It is connected to the high potential side end of the smoothing circuit and is connected to the first and second ends.
The connection point of the transistor is connected to the low potential side end of the smoothing circuit, and the base of the NPN type third transistor is connected to the high potential side end of the smoothing circuit via the first resistor. The bases of the first and second transistors are connected to the emitters of the transistors of the first and second transistors via the second and third resistors, respectively, and the ends of the feedback winding of the oscillation transformer are connected to the bases of the first and second transistors. And a base power supply capacitor is connected to both ends of the base drive power supply winding of the oscillation transformer through rectifying diodes, and the low potential side of the base power supply capacitor is connected to the low potential side end of the smoothing circuit. The high potential side of the base power supply capacitor is connected to the collector of the third transistor, and the discharge lamp is connected to the secondary winding of the oscillation transformer.

A fourth resistor is connected in series with the feedback winding of the oscillation transformer between the bases of the first and second transistors.

According to the configuration of the present invention, the fourth winding is connected in series with the feedback winding of the oscillation transformer between the bases of the first and second transistors.
Since the resistance of the third transistor is inserted and connected, it is possible to prevent a current from flowing from the emitter of the third transistor to the feedback winding of the oscillation transformer through the second and third resistors, and From emitter to second and third
Current flowing through the resistance of the first transistor can flow into the bases of the first and second transistors. As a result, when the output of the rectifier circuit is reduced by the pre-heating voltage dividing resistor as in the case of pre-heating after the power is turned on, even when the power is turned on with deep dimming, the first and second Can supply enough base current to the transistor
The switching operation of the first and second transistors can be activated, and the discharge lamp can be reliably activated / lighted.

Moreover, since the output voltage of the feedback winding is low and only the effective current is small, the power loss hardly increases even if the first resistor is inserted.

Furthermore, since only one resistor is added, the circuit configuration is simple and the cost is not high.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 and 2. This discharge lighting device, as shown in FIG.
A rectifier circuit II is connected to the AC power source E via a power control device I for phase control, and a smoothing circuit is connected to the output side of the rectifier circuit II via a parallel circuit of the preheating voltage dividing resistor R ₁ and the bypass switch element SCR. A leading preheating timer circuit III is provided for connecting the IV and turning on the bypass switch element SCR for a certain period of time after the power is turned on, and power is supplied to the two-stone push-pull inverter circuit V from both ends of the smoothing circuit IV. lamp
The LA is lit at high frequency.

The above-mentioned two-stone push-pull type inverter circuit V is push-pull connected to the primary winding of the oscillation transformer OT ₁ to connect the NPN type first and second transistors Q ₃ and Q ₄ and the resonance capacitor C ₄ in parallel, the oscillation primary winding N ₁ of the transformer OT ₁
Is connected to the high potential side end of the smoothing circuit IV, and the connection point of the first and second transistors Q ₃ and Q ₄ is connected to the low potential side end of the smoothing circuit IV. IV
Of the NPN type third transistor Q ₂ is connected to the high potential side end of the third transistor Q ₂ via the first resistor R _2, and the emitter of the third transistor Q ₂ has the second and third resistors R ₃ respectively. , R ₄
The bases of the first and second transistors Q ₃ and Q ₄ are connected to each other, and both ends of the feedback winding N ₃ of the oscillation transformer OT ₁ are connected to the bases of the first and second transistors Q ₃ and Q ₄ . base respectively connected to a capacitor C ₃ for the base power source via a rectifying diode D ₄ to both ends of the base drive power supply side winding N ₂ of the oscillation transformer OT _1, the low potential of the base power supply capacitor C ₃ Side is connected to the low potential side end of the smoothing circuit IV, the high potential side of the base power supply capacitor C ₃ is connected to the collector of the third transistor Q ₂ , and the secondary winding of the oscillation transformer OT ₁ is connected. The discharge lamp LA is connected to.

A fourth resistor R ₅ is connected in series with the feedback winding N ₃ of the oscillation transformer OT ₁ between the bases of the first and second transistors Q ₃ and Q ₄ .

The difference between the discharge lamp lighting device of this embodiment and the conventional example is
Other than that, a fourth resistor R ₅ is added, which is the same as the conventional example.

In the discharge lamp lighting device of this embodiment, a fourth resistor R ₅ is connected in series with the feedback winding N ₃ of the oscillation transformer OT ₁ between the bases of the first and second transistors Q ₃ and Q _4. Therefore, the current from the emitter of the third transistor Q ₂ can be prevented from flowing into the feedback winding N ₃ of the oscillation transformer through the second and third resistors R ₃ and R ₄ , and the third Transistor Q ₂
Currents I ₁ and I ₂ flowing from the emitter of the transistor through the second and third resistors R ₃ and R ₄ can flow into the bases of the first and second transistors Q ₃ and Q ₄ as shown in FIG. it can.

As a result, when the output of the rectifying bottleneck II is attenuated by the pre-heating voltage dividing resistor R ₁ as in the case of pre-heating immediately after the power is turned on, even when the power is turned on with deep dimming, the first and a second transistor Q _3, Q can supply sufficient base potential to _4, the switching operation of the first and second transistors Q _3, Q ₄ can be activated, ensures the discharge lamp LA It can be started and turned on.

Moreover, since the output voltage of the feedback winding N ₃ is low and the effective current is small, the power loss hardly increases even if the fourth resistor R ₅ is inserted.

Furthermore, only one resistor R ₅ is added to the conventional example, and the circuit configuration is simpler and the cost is hardly higher than the conventional example.

Discharge lamp lighting devices similar to the circuit configuration of this embodiment include those disclosed in Japanese Patent Application Laid-Open No. 39-4555, Japanese Patent Publication No. 55-24350, and Japanese Patent Publication No. 57-58035.

First, the inverter circuit disclosed in Japanese Patent Laid-Open No. 39-4555 discloses a resistor R ₇ and a capacitor in series with the feedback winding N ₃ of the oscillation transformer OT between the bases of the transistors Q ₃ and Q ₄ shown in FIG. The series circuit of C ₅ is inserted. Further, in the transistor inverter disclosed in Japanese Patent Publication No. 55-24350 shown in FIG. 7, only the capacitor C ₆ is inserted in series instead of the series circuit of the resistor R ₇ and the capacitor C ₅ .
Further, in the discharge lamp lighting device disclosed in Japanese Patent Publication No. 57-58035 shown in FIG. 8, a parallel circuit of a resistor R ₁₂ and a capacitor C ₇ is used instead of the series circuit of the resistor R ₇ and the capacitor C _5. Are inserted in series.

However, these similar discharge lamp lighting device are both in the configuration for supplying a base current directly to the transistor Q _3, Q ₄ from the power source, as in the above embodiment, the transistors Q _3, Q
_{4, the} base current is supplied from the power supply as much as necessary for startup, and after startup, the base drive power supply winding N of the oscillation transformer OT _1
This is completely different from the configuration in which the base current is supplied from ₂ to the transistors Q ₃ and Q ₄ . Further, the timer is not configured to perform pre-heating. Furthermore, it is not configured to perform dimming. Therefore, the drawbacks described in the [Background Art] section of this specification do not exist fundamentally and cannot be the prior art of the present invention.

〔The invention's effect〕

According to the discharge lamp lighting device of the present invention, the first and second
Since a fourth resistor is connected in series between the bases of the transistors of the oscillation transformer and the feedback winding of the oscillation transformer, the current from the emitter of the third transistor passes through the second and third resistors to the feedback winding of the oscillation transformer. It can be prevented from flowing into the line, and the current flowing from the emitter of the third transistor through the second and third resistors can flow into the bases of the first and second transistors. As a result, in the case where the output of the rectifier circuit is attenuated by the resistance for the pre-heating as in the case of the pre-heating immediately after the power is turned on, even when the power is turned on in the deep dimming state, the first and second transistors A sufficient base current can be supplied to the discharge lamp, the switching operation of the first and second transistors can be started, and the discharge lamp can be surely started and turned on.

Moreover, since the output voltage of the feedback winding is low and the effective current is small, even if the fourth resistor is inserted,
Power loss hardly increases.

Furthermore, since only one resistor is added, the circuit configuration is simple and the cost is not high.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing the structure of an embodiment of the present invention, and FIG.
FIG. 1 is a circuit diagram of a part of the two-stone push-pull type inverter circuit of FIG. 1, FIG. 3 is a circuit diagram showing a configuration of a conventional discharge lamp lighting device, and FIG. 4 is a two-stone push-pull type inverter of FIG. Circuit diagram showing a part of the circuit, FIG. 5 (a), (b)
Is a waveform diagram of the voltage across the smoothing circuit, FIG. 6, FIG. 7, and FIG.
The figure is a circuit diagram of another conventional example. I ... Power regulator, II ... Rectifier circuit, III ... Preheating timer circuit, IV ... Smoothing circuit, V ... Two-stone push-pull inverter circuit, E ... AC power supply, SCR ... Bypass Switch element, R ₁ …… Prediction resistor for preheating, R ₂ …
… The first resistor, R ₃ … the second resistor, R ₄ … the third resistor,
R ₅ ...... 4th resistor, Q ₂ ...... 3rd transistor, Q ₃ ......
1st transistor, Q ₄ ... 2nd transistor, C ₃ ...
… Base power supply capacitor, C ₄ …… Resonance capacitor, D ₄
...... Rectifying diode, LA ...... Discharge lamp, OT ₁ …… Oscillation transformer, N ₂ …… Base drive power supply winding, N ₃ …… Feedback winding

Claims (1)

(57) [Claims] 1. A rectifier circuit is connected to an AC power source via a power control device of a phase control type for dimming, and a parallel circuit of a preceding preheating voltage dividing resistor and a bypass switch element is connected to the output side of this rectifier circuit. A smoothing circuit is connected via the NPN type first and second NPN-type push-pull connected to the primary winding of the oscillating transformer. Two transistors and a resonance capacitor are connected in parallel, the middle point of the primary winding of the oscillation transformer is connected to the high potential side end of the smoothing circuit, and the connection point of the first and second transistors is connected to the smoothing circuit. The end of the smoothing circuit is connected to the low potential side end, the base of the NPN type third transistor is connected to the high potential side end of the smoothing circuit via the first resistor, and the emitter of the third transistor is connected to the base of the NPN type third transistor. Through the second and third resistor connecting the base of said first and second transistors,
Both ends of the feedback winding of the oscillation transformer are connected to the bases of the first and second transistors, respectively, and a base power supply capacitor is connected to both ends of the base drive power supply winding of the oscillation transformer via a rectifying diode. The low potential side of the base power supply capacitor is connected to the low potential side end of the smoothing circuit, the high potential side of the base power supply capacitor is connected to the collector of the third transistor, and the secondary side of the oscillation transistor is connected. In a discharge lamp lighting device in which a discharge lamp is connected to a winding, a fourth resistor is inserted and connected in series with the feedback winding of the oscillation transformer between the bases of the first and second transistors. Discharge lamp lighting device.