JP3003419B2 - Fluorescent 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 fluorescent lamp lighting device and, more particularly, to a starting device using a semiconductor switching element for a fluorescent lamp having a preheating electrode.

[0002]

2. Description of the Related Art Conventionally, as a starting device for a fluorescent lamp,
Glow starters were mainly used,
There are drawbacks such as a long start-up time and a short life. Recently, a starting device using a semiconductor switching element has been developed, but it has been expensive and has a limited demand. For this reason, there is a demand for the development of an inexpensive circuit device with a starting device using a semiconductor switching element. Based on the above request, a circuit as shown in FIG. 4 using an inexpensive transistor as a semiconductor switching element has been proposed (Japanese Patent Laid-Open No. 3-252096).

Referring to FIG. 4, the fluorescent lamp lighting device includes a series circuit of a ballast 2 connected to an AC power supply 1 and a fluorescent lamp 3 having a pair of preheating electrodes 4 and 5. A series circuit of the resistor 20 and the collector-emitter of the transistor 7 is connected between the power supply side preheating electrodes via the diode 6. The diode 6 is connected to the base of the transistor 7 via a resistor 14, and a thyristor 12 controlled by a timer circuit composed of the resistor 8 and the capacitor 10 is connected between the base and the emitter of the transistor 7. ing. The capacitor 10 includes a Zener diode 13 and a resistor 21.
Is connected to the gate circuit of the thyristor 12 through the gate. A noise prevention capacitor 19 is connected between the non-power supply side preheating electrodes of the fluorescent lamp 3.

Next, the operation of the lighting device thus configured will be described. When the AC power supply 1 is turned on, the base current of the transistor 7 is supplied to the base of the transistor 7 via the resistor 14 when the power supply voltage is in a positive cycle. Flows. As described above, a half-wave of the preheating current flows to preheat the preheating electrodes 4 and 5 of the fluorescent lamp 3, and when the time set by the timer circuit is reached, the charge of the capacitor 10 is charged to the gate of the thyristor 12 by the timer circuit. The thyristor 12 flows through the Zener diode 13 and the resistor 21.
Turns on. As a result, since the collector current of the transistor 7 is turned off, a pulse voltage is generated due to the inductance of the ballast 2 and the fluorescent lamp 3 is turned on.

[0005]

However, in such a conventional lighting device, the timing when the time set by the timer circuit is reached is when the voltage of the capacitor 10 is equal to the Zener voltage of the Zener diode 13 and the thyristor 12 is turned on. This is a time when the voltage becomes a value near the added value of the required gate-cathode voltage, which varies due to a variation or change of the Zener voltage or the capacitance of the capacitor. For this reason, it is difficult to always generate a pulse voltage at a predetermined AC power supply phase, and the transistor 7 may be turned off when the voltage and current values at both ends of the fluorescent lamp 3 according to the AC power supply phase are small. There was a problem that the fluorescent lamp 3 could not be started because the pulse voltage was small.

An object of the present invention is to provide a fluorescent lamp lighting device which can surely start a fluorescent lamp with one start pulse and has a simple structure.

[0007]

A fluorescent lamp lighting device according to the present invention comprises a series circuit of a ballast to be connected to an AC power supply and a fluorescent lamp with a preheating electrode, and a non-power supply side preheating electrode of the fluorescent lamp. A transistor having a collector and an emitter connected via a diode, a timer circuit having a resistor and a capacitor operated by a voltage between the collector and the emitter of the transistor, a part of a voltage generated in the resistor of the timer circuit, Transistor-based drive control means for switching the transistor with a voltage added to the voltage of the capacitor, and starting the fluorescent lamp.
Pulse voltage for the voltage across the fluorescent lamp
There is a configuration to generate near the peak of the current phase.
Is what you do.

[0008]

According to the present invention, the transistor is switched by the addition voltage of a part of the voltage generated in the resistor of the timer circuit operated by the voltage between the collector and the emitter of the transistor and the voltage of the capacitor, whereby the timer circuit is switched. The divided voltage value of the voltage between the collector and the emitter of the transistor for each cycle is superimposed on the voltage of the capacitor that increases according to the time constant of the capacitor and the resistor. as a result,
When the slowly rising capacitor voltage approaches a predetermined voltage for turning on the transistor base drive control means, the transistor base drive control means is turned on by the peak of the superimposed voltage ripple in each cycle superimposed on the capacitor voltage. Therefore, the pulse voltage for starting the fluorescent lamp is always generated near the peak of the voltage / current phase at both ends of the fluorescent lamp.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a fluorescent lamp lighting device according to an embodiment of the present invention includes a series circuit of a ballast 2 connected to an AC power supply 1 and a fluorescent lamp 3 having a pair of preheating electrodes 4 and 5. A diode 6 is connected between the preheating electrodes on the non-power supply side of the fluorescent lamp 3.
7 whose collector and emitter are connected via
A timer circuit 11 composed of a resistor 8, a resistor 9 and a capacitor 10 composed of an electrolytic capacitor operated by a voltage between the collector and the emitter of the transistor 7; and a voltage of the capacitor 10 of the timer circuit 11 and a voltage generated at the resistor 9. A thyristor 12 for switching the transistor 7 with the added voltage of the above, a transistor base drive control means 15 including a Zener diode 13 and a resistor 14,
It comprises a series circuit of a resistor 17 and a surge absorber 18 connected in parallel to a series circuit of a transistor 7 and a diode 16 connected in series with its collector-emitter. A noise prevention capacitor 19 is connected between the non-power supply side preheating electrodes of the fluorescent lamp 3 as usual.

Next, the operation of such a lighting device will be described. Before the fluorescent lamp 3 is started, when the power supply voltage is in a positive cycle, a base current is supplied to the base of the transistor 7 through the resistor 14 and the diode 16, so that a large amount of power is supplied from the AC power supply 1 through the diode 6. Collector current flows. At this time, the power supply of the timer circuit 11 composed of the resistor 8, the resistor 9, and the capacitor 10 is shown in FIG.
5 shows the collector-emitter voltage of the transistor 7 having the waveform shown in FIG. Thus, a half-wave of the preheating current flows, and the preheating electrodes 4 and 5 of the fluorescent lamp 3 are preheated. Timer circuit 1
The voltage at the connection point between the resistor 8 and the resistor 9 which is the output voltage of No. 1 is, as shown in FIG. It becomes the added voltage. At this time, the voltage of the resistor 9 is approximately equal to the collector-emitter voltage of the transistor 7.
And the resistance 8. Therefore, the voltage waveform of the resistor 9 is similar to the collector-emitter voltage waveform of the transistor 7. The voltage waveform of the capacitor 10 is
A time constant of T = C ₁₀ × (R ₈ + R ₉ ) (where C ₁₀ represents the capacitance value of the capacitor 10 and R ₈ and R ₉ represent the resistance values of the resistors 8 and ₉ ) for each preheating half-wave cycle. And rise slowly. Therefore, the output voltage waveform of the timer circuit 11 is obtained by superimposing the divided voltage value of the voltage between the collector and the emitter of the transistor 7 every cycle on the voltage of the capacitor 10. As a result, the slowly rising capacitor voltage becomes the predetermined voltage Vt for turning on the thyristor 12.
, The thyristor 12 is turned on by the peak of the superimposed voltage ripple in each cycle superimposed on the voltage of the capacitor 10. Therefore, the pulse voltage is always generated near the peak of the voltage / current phase at both ends of the fluorescent lamp 3. That is, when the current / voltage phase near the peak of the time ts set by the timer circuit 11 is reached, the charge from the capacitor 10 and the AC power supply 1 flows through the Zener diode 13 to the gate terminal of the thyristor 12, The thyristor 12 is turned on. Next, since the collector current of the transistor 7 is turned off near its peak value, a pulse voltage _VL due to the inductance of the ballast 2 is generated,
The fluorescent lamp 3 is turned on. The pulse voltage V at this time
_L has a fixed size due to the resistor 17 and the surge absorber 18, and is represented by equation (1).

V _L = I × (L / (C ₁₉ + C _L )) ^1/2 (1) (where I is the inductance current immediately before the transistor 7 is turned off, and L is the ballast 2 Inductance value, C
₁₉ is the capacitance value of the noise prevention capacitor, C _L is the stray capacitance, and the energy W held by the inductance at this time.
_L is represented by equation (2).

W _L = L × I × I / 2 (2) That is, since a current having an inductance substantially equal to the collector current of the transistor 7 is turned off near its peak value, a ballast is provided. W the energy of the pulse voltage generated in 2 _L becomes the largest in the pulse generation phase. Therefore, the reduction in the pulse voltage due to the noise prevention capacitor 15 and the like can be reduced and the pulse width can be widened. Therefore, the energy for transition to arc discharge after the breakdown of the fluorescent lamp 3 can always be increased. As a result, the pulse voltage generated by the lighting device of the present invention can easily start the fluorescent lamp 3 more stably. At the same time, since the fluorescent lamp 3 can be broken down near the peak of the current phase, the arc discharge current immediately after the breakdown can be increased, and the current half cycle period can be sufficiently long. Can be stable. Therefore, the fluorescent lamp 3 can be started more stably even in a situation where the ambient temperature is low.

Further, since the pulse width can be widened, a predetermined pulse voltage for lighting the fluorescent lamp can be maintained even in a ballast of poor performance in which the frequency-inductance characteristic of the ballast 2 does not extend to a high frequency of 30 to 40 kHz. It is possible to obtain a fluorescent lamp lighting device that can be secured and has higher versatility.

Next, when the fluorescent lamp 3 is turned on, the voltage between the non-power-supply-side preheating electrodes is also reduced to the lamp voltage at the time of lighting. Further, when the fluorescent lamp 3 is lit, the potential of the capacitor 10 hardly decreases in the AC half cycle due to the resistor 9 and the thyristor 12 is kept on. That is, the transistor 7 is kept off, and the pulse generation operation is stopped. As a result, the fluorescent lamp 3 is stably turned on.

As described above, the fluorescent lamp lighting apparatus according to the embodiment of the present invention has a simple and inexpensive configuration in which the resistor 9 is inserted in series with the capacitor 10 of the timer circuit 11 to reduce the generation phase of the pulse voltage to the preheating current half. It can be near the peak value of the cycle. Further, with this circuit, the fluorescent lamp 3 can be started reliably and stably with a single pulse voltage using a general-purpose ballast regardless of the surrounding conditions. Therefore, the circuit can be made simpler and cheaper.

As an example, in the circuit configuration shown in FIG. 1, the resistor 8 has a resistance of 36 kΩ and the resistor 9 has a resistance of 100 kΩ.
An experiment was performed using Ω, a capacitor 10 having a capacitance value of 47 μF, and a Zener diode 13 having a Zener voltage of 5.1 V. As a result, it was confirmed that the pulse voltage can be reliably started only once.

In the above embodiment, as the base drive control means for the transistor, the transistor 7 is turned on until the output voltage of the timer circuit 11 reaches a predetermined value, and the thyristor 12 is turned on when the output voltage of the timer circuit 11 reaches the predetermined value. Although an example of the circuit configuration for turning off the transistor 7 has been described, it is needless to say that the present invention is not limited to such a circuit configuration. Further, the diode 16 is not always necessary.

[0019]

As described above, the fluorescent lamp lighting device of the present invention has an excellent effect that the fluorescent lamp can be reliably started with a single pulse voltage with an inexpensive configuration.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a fluorescent lamp lighting device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a collector-emitter voltage waveform of a transistor.

FIG. 3 is an output voltage waveform diagram of a timer circuit.

FIG. 4 is a circuit diagram of a conventional fluorescent lamp lighting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Ballast 3 Fluorescent lamp 4,5 Preheating electrode 7 Transistor 8,9 Resistance 10 Capacitor 11 Timer circuit 12 Thyristor 15 Transistor base drive control means

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuhiko Ito 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-3-252094 (JP, A) JP-A-57- 134891 (JP, A) JP-A-57-172698 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 41/18

Claims (1)

(57) [Claims] 1. A series circuit of a ballast to be connected to an AC power supply and a fluorescent lamp with a preheating electrode, a transistor having a collector and an emitter connected via a diode between a non-power supply side preheating electrode of the fluorescent lamp, A timer circuit having a resistor and a capacitor that operate with a voltage between the collector and the emitter of the transistor; and switching the transistor with a sum of a part of a voltage generated in the resistor of the timer circuit and a voltage of the capacitor. Transistor-based drive control means for controlling the fluorescent lamp.
A pulse voltage for starting is applied to both ends of the fluorescent lamp.
A fluorescent lamp lighting device characterized in that it is generated near a peak of a voltage / current phase .