JPS6286698A - Burning apparatus of discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a lighting device for a discharge lamp, and particularly to a circuit configuration suitable for obtaining a highly efficient and low-cost discharge lamp lighting device.

[Background of the invention]

As a conventional example of a discharge lamp lighting device, there is a device as shown in FIG. 1 in Japanese Patent Application Laid-Open No. 58-161297.

In the conventional device shown in Fig. 1, 1 is an AC power supply.

2 is a full-wave rectifier, 3 is a constant current reactor, 4 and 5 are base resistors, and 6 and 8 are transistors.

8 is a resonant capacitor, 9 is a primary winding 9a, 9b, a feedback winding 9c, a preheating winding 1Q9d and 9f, a secondary winding 1lA9e
10 is a discharge lamp, and ]1 is a smoothing capacitor. Explain the operation to fll'IQL.

When the AC power supply 1 is turned on, it is converted to DC by the rectifier 2, and is connected to the transistor 6 via the base resistors 4 and 5.
The bases of and 7 are positively biased. Then, due to slight variations in the characteristics of transistors 6 and 7, one of the transistors is turned on. By turning on one of the transistors, the primary winding 9 of the transformer 9
A and 9b and a voltage is generated in feedback winding 9c, and a feedback signal is fed back to transistors 6 and 7, thereby starting oscillation. Thereafter, oscillation continues at a frequency approximately determined by the value of the resonant capacitor 8 of the inductance on the primary side of the transformer 9. At this time, a no-load secondary voltage is generated on the secondary side of the transformer 9, and a preheating current flows through the pair of filaments of the discharge lamp 10, thereby lighting the discharge lamp 10.

However, in order for the above circuit to continue operating stably,
1.1 of the collector current is applied to the bases of transistors 6 and 7 through base resistors 4 and 5. It is necessary to supply a base current of /hpa or higher. Therefore, the power consumption in the base resistors 4 and 5 is large, resulting in a decrease in circuit efficiency and a decrease in reliability due to an increase in the temperature of the circuit elements when assembled in a single housing. In addition, the cost increases due to the complexity of the structure and process due to measures such as attaching a heat sink to suppress the rise in element temperature, and the increase in the temperature grade of the element.

There was a runner-up.

[Purpose of the invention]

The purpose of the present invention is to eliminate the above-mentioned runner-up problems and to improve efficiency and reliability. One object of the present invention is to provide an inexpensive discharge lamp lighting device.

[Summary of the invention]

A feature of the present invention is that the source of the base current of the transistor, which is essential for stable continuation of oscillation, is obtained through the discharge lamp and its filament. The power consumption in the resistor is large because the base current is supplied through the base resistor, but it can be supplied from the low voltage section, so the power consumption in the base resistor can be reduced.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows an embodiment of the invention. In Figure 2, LO
a and 10b are a pair of filaments of the discharge lamp 10;
2 is a starting resistor, 15 is a constant voltage diode, 16 is a capacitor, 17 and 18 are base resistors, 19 is a rectifier circuit, and the same reference numerals as in FIG. 1 indicate the same or equivalent parts.

When the AC power supply 1 is turned on, it is converted to DC by the Kinwave rectifier 2 and the smoothing capacitor 11, and the starting resistor 12. Transistors 6 and 7 via base resistors 17 and 18
The base of is positively biased. Then transistor 6
Due to slight variations in the characteristics of and 7, one of the transistors is turned on. By turning on one of the transistors, a voltage is generated in the primary windings 9a and 9b of the transformer 9 and the feedback winding 9c, and the feedback signal is fed back to the transistors 6 and 7, thereby starting oscillation. At the same time, a voltage is also generated in one of the preheating windings 9f of the lances 1 to 9, and a current flows through one of the filaments 10b of the discharge lamp 10 and the rectifier circuit 19, charging the capacitor 16, and the capacitor 16 maintains a constant voltage. When charged to the above level, base current is supplied to the bases of transistors 6 and 7 via base resistors 17 and 18 to continue stable oscillation. In this state, the secondary winding B9 of transformer 9
A no-load secondary voltage is generated at e, and a preheating current also flows through the other filament 10a of the discharge lamp 10.
0 is lit. 1 after lighting is discharge lamp 10. Base current is supplied to the bases of transistors 6 and 7 via rectifier circuit 19 and base resistors 17 and 18 to continue stable operation.

Furthermore, by connecting the constant voltage diode 15 to both ends of the capacitor 16, a stable base current can be supplied even if the power supply voltage etc. fluctuate.

In this way, according to this embodiment, the starting resistor 12 connected to the high voltage section only needs to flow a minute current necessary for starting oscillation, and most of the base current is passed through the capacitor 16.
Since the power is supplied from the low voltage sections at both ends of the base resistor, power loss in the base resistor can be extremely small.

In the embodiment shown in FIG. 2, the same effect can be obtained by using either an afterwave rectifier or a half-wave rectifier as the rectifier circuit 19. Furthermore, as shown in FIG. 3, the same effect can be obtained by connecting a constant voltage diode 20 and a diode 21 in place of the rectifier circuit 19 and constant voltage diode 15 in FIG. 2, and the number of components can be reduced. A small device is obtained.

Also, preheating windings 9d and 9f of the transformer 9.

Adjustment of the number of windings, or the intermediate tap on the secondary side preheating winding 9d of the transformer 9 and the filament log of the discharge lamp 10
Unbalanced preheating can be prevented by inserting a suitable impedance element between the two and balancing the preheating currents flowing through the filaments 10a and 10b of the discharge lamp 10.

〔Effect of the invention〕

As explained above, according to the present invention, the base current of the transistor of the discharge lamp lighting device is supplied through one preheating winding of the transformer and one filament of the discharge lamp, thereby increasing the power supply in the bias circuit. It is possible to achieve high efficiency by suppressing crab/g costs, and it is also possible to suppress excess heat generation. This lowers the temperature inside the housing, which can improve reliability.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram explaining the circuit configuration of a conventional discharge lamp lighting device, Fig. 2 is a circuit diagram showing one embodiment of the present invention, and Fig. 3 is a circuit diagram showing another embodiment of the present invention. It is. 9... Transformer, 10... Discharge lamp, 15... Constant voltage diode, 16... Capacitor, 17... and 18... Base resistor, 19... Rectifier circuit, 20...
... Constant voltage diode, 21... Diode.

Claims (1)

[Claims] 1. A oscillator that uses a DC power supply as a power supply source, is equipped with an oscillation passive element and at least one transistor, and performs self-oscillation operation by feeding back a feedback signal to the base of the transistor using a feedback circuit. a transistor inverter comprising a circuit, a base bias circuit of the transistor, and a ballast element for limiting the current of the discharge lamp;
In a discharge lamp lighting device comprising the discharge lamp driven by the output of the transistor inverter and a preheating circuit that preheats a filament of the discharge lamp, power for the base bias circuit is obtained through the discharge lamp and the filament. A discharge lamp lighting device characterized by: