JPH0658826B2 - Electronic fluorescent discharge lamp lighting device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent discharge lamp lighting device, and in particular, to prevent wasteful power consumption and destruction and deterioration of parts and the like at the end of the life of the fluorescent discharge lamp. The present invention relates to an electronic fluorescent discharge lamp lighting device having a protection circuit.

[Conventional technology and problems]

Conventionally used fluorescent discharge lamp lighting devices include glow starters, rapid starters, electronic starters and the like.

Among them, the glow type starter has a problem that it takes a long time to light up, and since the starter contact portion is made of bimetal, it has a long operation time and a short life.

Further, since the leakage type transformer used in the rapid starter is heavy and expensive, development efforts have been made for practical use of the electronic starter for the past several years.

For example, Japanese Patent Publication No. 56-14000 discloses an electronic lighting device having a circuit configuration as shown in FIG.

Briefly explaining this, AC power supply (power supply voltage)
After the AC is turned on, during the positive half cycle, when the divided voltage of the resistors R2 and R3 reaches the operating voltage of the thyristor Q1 (point a in FIG. 3), the thyristor Q1 becomes conductive,
AC power supply AC → Choke transformer CH → Fluorescent discharge lamp FL
First heater H1 → thyristor Q1 → diode D2
→ The second heater H2 of the fluorescent discharge lamp FL → The preheating current Ih flows through the path of the AC power supply AC, and the heater HI of the fluorescent lamp FL,
H2 is heated. This preheating current Ih becomes a delay current due to the choke transformer CH and continues to flow even during the negative half cycle of the power supply voltage AC following the positive half cycle. Q1 is cut off.

In the negative thyristor, the gate G of the thyristor Q1 has an AC power supply AC → a resistor R1 → a diode D1 → a gate G of the thyristor Q1 → a cathode K of Q1 → a diode D.
Since the reverse bias voltage V _RG is applied in the path of 2 → heater H2 → AC power supply AC, the commutation point b of the preheating current Ih
At the same time, the holding current IH becomes substantially larger, and therefore dv / dt is improved, and the reaction effect of the choke coil CH with respect to such a rapid change in current causes the anode-cathode (A-K) of the thyristor Q1. ), A kick pulse Vp is generated, which is applied between both electrodes (heaters H1, H2) of the discharge lamp. Such an operation is continuously repeated for several cycles, and the heater H
When 1 and H2 are heated, the fluorescent discharge lamp FL is lit by discharge. In this discharge state, the voltage between both electrodes of the discharge FL, that is, the tube voltage decreases, the trigger voltage by the resistors R2 and R3 decreases, and the thyristor Q1 turns off.
After that, the fluorescent discharge lamp is kept in the off state during discharging.

By the way, in the conventional electronic lighting device as described above, when the end of the life of the fluorescent lamp is approached, a state in which it is not possible to shift to full discharge due to deterioration of the gas state in the discharge lamp occurs, but in such a state However, since the lighting device continues to generate pulses, power is uselessly consumed without being able to achieve complete discharge, noise continues to be generated, and thyristors and other parts are destroyed and deteriorated. There was a problem.

As one solution to this problem, Japanese Examined Patent Publication No. 54-24233
As shown in FIG. 4 of the publication, a series circuit of a resistor 11 and a transistor 12 is connected between the gate and cathode of the thyristor 6, and a time constant capacitor 13 is connected between the base and emitter of the transistor 12. Further, a discharge lamp starting device equipped with a current detection resistor 10 connected in series with the thyristor 6 and a timer circuit with a CR time constant circuit in which this capacitor 13 is connected in parallel via a time constant resistor 14 and a diode 15 Is listed.

In this circuit, since there is no charge in the capacitor 13 at first, the impedance between the collector and the emitter of the transistor 12 is large. Therefore, immediately after the power is turned on, the same operation as in the circuit of FIG. A current Ih is passed.

At this time, a current flows through the current detecting resistor 10, and due to this voltage drop, the time constant capacitor 13 is gradually charged via the time constant resistor 14 and the diode 15.

Therefore, a current flows through the base of the transistor 12 and a current also flows between the collector and the emitter of the transistor 12, the transistor 12 becomes conductive, and the resistor 11 is connected between the gate and the cathode of the thyristor 6. Therefore, the gate current of the thyristor 6 is reduced, the ignition phase angle of the thyristor 6 is delayed, and the preheating current Ih is reduced.

Further, when the preheating current Ih decreases, the voltage drop of the current detection resistor 10 also decreases and the charging current voltage of the capacitor 13 also decreases, so that the base current of the transistor 12 decreases and the preheating current Ih increases. As a result, the preheating current Ih is maintained at a constant idling current I _L as shown in FIG.

As described above, in this circuit, by reducing the preheating current Ih after the elapse of the timer time determined by the terminal voltage of the current detection resistor 10, the time constant resistor 14, and the time constant of the time constant capacitor 13, the fluorescent discharge lamp is reduced. It is designed to prevent a large current from continuously flowing to the ballast 2 and the thyristor 6 for a long time when the lamp does not light up at the end of its life.

[Problems to be Solved by the Invention]

However, in the discharge lamp starting device shown in FIG.
There is a drawback that the idling current I _L shown in FIG. 5 cannot be further reduced.

That is, in the above timer circuit, the preheat current is detected by the current detection resistor 10, and the transistor 12 is driven by the detected voltage, and the base-emitter voltage of the transistor 12 is V _BE (ON) = 0.7V. Then, between the idling current I _L and the current detection resistor 10, Have a relationship.

Therefore, if the current detection resistor 10 is increased in order to reduce the idling current I _L , the preheating current Ih flowing at the time of starting is limited, which causes trouble in lighting.

Therefore, the idling current I _L cannot be reduced so much, and therefore, there is a problem that it is necessary to take measures such as a power loss due to the idling current I _L that flows and heat generation of the thyristor 6 and the current detection resistor 10.

Therefore, an object of the present invention is to provide an electronic fluorescent discharge lamp lighting device that further reduces the idling current without reducing the preheating current and does not require measures against power loss and heat generation.

[Means for Solving the Problems]

In order to solve the above problems, in the present invention, the preheating current of the preheating electrode is detected, and when normal lighting is not achieved within a predetermined time, the transistor is operated via the CR time constant circuit to limit the preheating current. In a conventional electronic fluorescent discharge lamp lighting device provided with a protection circuit for reducing or stopping the generation of kick pulse applied to the discharge lamp, the protection circuit further limits the preheating current limiting action of the transistor in the stopping direction. That is, the positive feedback circuit for energizing is provided.

[Action]

In the electronic fluorescent discharge lamp lighting device configured in this way,
When the discharge lamp is started and lit, the trigger circuit of the electronic lighting circuit ignites the thyristor, conducting and interrupting the thyristor every half cycle of alternating current to heat the preheating electrode and apply a kick pulse. To do.

At this time, the protection circuit turns on the discharge lamp in the fully discharged state by the preheating current detected by the current detection resistor until the CR time constant circuit times up, and the tube voltage decreases to decrease the preheating current. If not observed, the CR time constant circuit is timed up to drive the transistor, delay the trigger phase angle of the trigger circuit, for example, to limit the preheat current, and reduce or stop the generation of the kick pulse.

At this time, the positive feedback circuit directly urges the limiting action of the preheating current of the transistor toward the stop direction regardless of the presence or absence of the preheating current detected by the current detection resistor, thereby maintaining the transistor in a saturated state, for example. In this way, the trigger operation of the thyristor by the trigger circuit can be prohibited, and the idling current can be reduced or eliminated by maintaining the limited state of the preheating current.

〔Example〕

An embodiment of the electronic fluorescent discharge lamp lighting device of the present invention will be described below with reference to FIG.

The electronic fluorescent discharge lamp lighting device of the illustrated embodiment comprises an electronic lighting circuit unit I and a protection circuit II. The electronic lighting circuit unit I includes voltage dividing resistors R11 and R12, a choke transformer CH, a noise preventing capacitor C11, and a resistor R13. , Fluorescent discharge lamp F
The L filaments Fa and Fb, the reverse bias circuit diode D11, the capacitor C12, the thyristor Q11, the resistors R14, R15 and R16, the current detection resistor R17, the zener diode ZD11, and the capacitor C14.

The operation of the lighting circuit unit I will be described. After the AC power supply AC is turned on, the divided voltage of the resistors R14 and R15 is increased by the Zener diode ZD during the half cycle of the AC power supply AC.
When the operating voltage of 11 is reached, the thyristor Q11 becomes conductive and the AC power supply AC → choke transformer CH → filament Fa of the fluorescent discharge lamp FL → thyristor Q11 → resistor 17
→ The filament Fb of the fluorescent discharge lamp FL → The preheating current Ih flows through the path of the AC power source AC, and the filament Fa,
Fb is heated.

Since this preheating current Ih becomes a delay current due to the choke transformer CH, it flows into the negative half cycle following the positive half cycle of the current voltage.

When the holding current IH of the thyristor Q11 becomes less than or equal to the holding current IH, the thyristor Q11 is cut off by natural commutation.

During this negative half cycle, the gate G of the thyristor Q11 has a dividing point of the dividing resistors R11 and 12 → a diode D11.
Since the reverse bias voltage V _RG is applied via, the dV / dt is improved by the same effect that the holding current IH substantially increases at the commutation point of the preheating current Ih.

For this reason, the choke transformer C for sudden current changes
A voltage pulse is generated between the anode and the cathode (AK) of the thyristor Q11 by the reaction effect of H, and this causes both electrodes (filaments Fa, F of the fluorescent discharge lamp FL).
applied during b).

Such an operation is continuously repeated for several cycles, and when the filaments Fa and Fb are sufficiently preheated, the fluorescent discharge lamp FL is turned on by discharge.

In this discharge state, the voltage between both electrodes of the fluorescent discharge lamp FL, that is, the tube voltage is lowered, and the Zener diode ZD11 is turned off by voltage decomposition by the resistors R14 and R15. As a result, the tube voltage of the fluorescent discharge lamp FL is While being maintained at the discharge voltage, the thyristor Q11 is cut off, and thereafter kept in the off state during the discharge.

Next, in this embodiment, the protection circuit II includes a preheating current control transistor Q12 and a positive feedback resistor R of the transistor Q12.
8, a resistor R20, a capacitor C14 forming a CR time constant circuit, a resistor R21, and a discharging resistor R19 of the capacitor C14.

This protection circuit II is used when the fluorescent discharge lamp FL cannot reach the complete discharge state within the timer time determined by the charging / discharging time constants of the capacitor C14 and the resistors R19 and R21 by repeating the above-described lighting operation for several cycles at the end of its life. Is
By limiting the preheating current Ih and preventing the generation of a kick pulse for starting discharge, useless power consumption and deterioration and destruction of parts are prevented.

That is, the thyristor Q11 repeats the on / off operation in the same cycle as the AC power supply AC in the state before the fluorescent discharge lamp FL is in the complete discharge state. In such a state, the capacitor 14 has the current detection resistor R17. The voltage between both ends of is applied via the resistor R21 to be charged.

At this time, by setting the time constant at the time of discharging via the resistor R19 to be longer than the time constant at the time of charging via the resistor R21, the capacitor C14 is charged, and the charging voltage thereof is the same as that of the transistor Q12. When the operating base-emitter voltage V _BE (about 0.7 V) is reached, the transistor Q12 is turned on via the resistor R20.

Therefore, both ends of the resistor R15 are short-circuited, the Zener diode ZD11 is turned off, and the thyristor Q11 is also turned off.

As a result, the voltage across R17 disappears, capacitor C14 discharges through resistor R19, and transistor Q14
12 turns off again. Then Zener diode Z
The D11 and the thyristor Q11 are turned on again, the above operation is repeated, and the preheating current is held at a constant idling current.

In this case, the preheating current when the thyristor Q11 is turned on is greatly limited to V _BE / R17 as compared with the case where the protection circuit II is not provided, and even if the thyristor Q11 is turned off, the kick pulse due to the reaction of the choke transformer CH is not generated.

Further, a resistor R8 having one end connected to the anode A side of the thyristor Q11 is connected to the base of the transistor Q12 as a positive feedback circuit.

The positive feedback circuit charges the capacitor C14, increases the base current of the transistor Q12, and brings the operating point of the transistor Q12 close to the saturation point during the positive half cycle of the AC power supply AC.

As a result, the transistor Q12 is always turned on during the operation of the protection circuit II and short-circuits both ends of the resistor R15.

Therefore, the Zener diode ZD11 is turned off,
The thyristor Q11 is held in the off state.

In this way, the positive feedback circuit holds the thyristor Q11 in the OFF state and urges the preheating current limiting action of the protection circuit II in the stopping direction.

Therefore, the preheating current limiting action of the transistor Q12 is further strengthened by the positive feedback circuit, and in reality, once the transistor Q12 conducts, the preheating current is completely cut off in a very short time and the state is maintained.

In this way, this protection circuit II uses the positive feedback circuit when the normal lighting state is not reached within a predetermined time (for example, within about 3 seconds) after the power is turned on at the end of the life of the fluorescent discharge lamp.
Since the preheating current can be interrupted and the high-voltage pulse can not be generated, wasteful power consumption can be eliminated, heat generation due to the power consumption does not occur, and deterioration and destruction of parts can be prevented.

The protection circuit is not limited to the configuration of the above-described embodiment, and the preheating current can be limited or cut off when the preheating current is detected and the fluorescent discharge lamp does not reach the complete discharge state within the predetermined time. Any known circuit configuration may be used as long as it is one.

〔The invention's effect〕

According to the electronic fluorescent discharge lamp lighting device of the present invention, by an inexpensive circuit configuration, at the end of the life of the fluorescent discharge lamp,
Obviously, it is possible to prevent wasteful power consumption and deterioration and destruction of parts, and it is possible to remarkably promote the practical application of the electronic fluorescent discharge lamp lighting device.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of an electronic fluorescent discharge lamp lighting device according to the present invention, FIG. 2 is a circuit diagram of an example of a conventional electronic fluorescent discharge lamp lighting device, and FIG. 3 is a description of its lighting operation. 4 is a circuit diagram of a conventional discharge lamp starting device, and FIG. 5 is an operation drawing of a conventional example. I ... Lighting circuit part, II ... Protection circuit, Q11 ... Thyristor, A ... Anode, G ... Gate, K ... Cathode, Q12 ... Transistor, R8 ... Positive feedback resistor, R19, R17 ... ... current detection resistor, R21 ... time constant resistor, C14 ... time constant capacitor, AC ... AC power supply, FL ... fluorescent discharge lamp, Fa, Fb ... filament (preheating electrode).

Claims (1)

[Claims] 1. An electrode end of the discharge lamp FL between a series circuit of an AC power supply AC, a ballast CH and a fluorescent discharge lamp FL with a preheating electrode and between non-power supply side preheating electrode terminals Fa and Fb of the discharge lamp FL. An electronic device in which a thyristor Q11 with a unidirectional control pole having a trigger circuit R14, R16, ZD11 for detecting a voltage and performing a control pole trigger for turn-on is connected so that its anode A end is on the ballast CH side. Lighting circuit I
A transistor Q12 connected between the gate G and the cathode K of the thyristor Q11; a current detection resistor R17 connected in series between the cathode K of the thyristor Q11 and the non-power supply side preheating electrode Fb of the discharge lamp FL; CR time constant circuits C14 and R21 connected between the connection point of the current detection resistor R17 and the thyristor Q11 and the transistor Q12.
When the preheating currents of the preheating electrodes Fa and Fb are detected and normal lighting is not achieved within a predetermined time, the transistor Q12 is operated via the CR time constant circuits C14 and R21 to limit the preheating current. In the electronic fluorescent discharge lamp lighting device provided with the protection circuit II for stopping the generation of the kick pulse V _P applied to the discharge lamp FL, the protection circuit II further stops the preheating current limiting action of the transistor Q12. An electronic fluorescent discharge lamp lighting device comprising a positive feedback circuit R8 for energizing.