JPS6386390A - Discharge lamp stabilizer - Google Patents

Abstract

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

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a main choke coil for generating a lamp starting voltage and an auxiliary choke coil for controlling a triac connected in parallel to maintain a constant lamp voltage. This invention relates to a discharge lamp ballast inserted in series with a power supply circuit.

(Prior Art) FIG. 2 is a circuit diagram showing the structure of a conventional discharge lamp ballast of this type. In the figure, a discharge lamp 1, a main choke coil 3 having a pulse generating circuit 2, and an auxiliary choke coil 5 to which a triac 4 is connected in parallel are connected in series to an AC power source 6. Of these, the pulse generating circuit 2 is composed of capacitors 21 and 22, diodes 23 and 24, a triac 25, and a resistor 26. here,
One end of the capacitor 21 is connected to the mutual junction of the main choke coil 3 and the auxiliary choke coil 4, and the other end of the capacitor 21 is connected to the anode of the diode 23. The cathode of this diode 23 is connected to one end of the AC power supply 6 via a resistor 26. Further, one end of the capacitor 22 is connected to the center tap of the main choke coil 3, and the other end of the capacitor 22 is connected to the cathode of the diode 24. The anode of this diode 24 is connected to the cathode of the diode 23. Further, a triac 25 is connected between the other end of the capacitor 21 and the other end of the capacitor 22.

In FIG. 2, triacs 4 and 25 are controlled by a circuit not shown, but if both are in the off state (hereinafter, turning off is referred to as OFF, and turning on is referred to as ON). , capacitor 21.
22 are each charged to a polarity determined by diodes 23 and 24. When the triac 25 is turned on, a pulsed discharge current flows through a portion of the main choke coil 3, and an extremely high lamp starting voltage is generated across the main choke coil 3, thereby lighting the discharge lamp 1. Thereafter, the triac 4 is controlled to keep the current phase constant and the lamp voltage constant to stabilize the light emitting state of the discharge lamp 1. This control method is widely known as phase control.

(Problems to be Solved by the Invention) In the conventional discharge lamp ballast described above, the main choke coil for generating lamp starting voltage by obtaining power from an AC power source is connected closer to the discharge lamp than the auxiliary choke coil. has been done. Therefore, when the impedance of the auxiliary choke coil is large, it is difficult to supply the necessary power, but in this case, two capacitors 21.
Since the charging voltages of 22 are discharged in a superimposed manner, the influence on the pulse waveform is relatively small.

However, there is a problem in that the configuration of the pulse generation circuit becomes complicated in order to deal with two capacitors.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a ballast for a discharge lamp that can significantly simplify the configuration of a pulse generation circuit for generating a lamp starting voltage.

(Means for Solving the Problems) The present invention has a triac connected in parallel with a first choke coil that generates a lamp starting voltage by passing a pulsed current, and controls the triac to generate a lamp voltage. A ballast for a discharge lamp in which a second choke coil that maintains a substantially constant state is inserted in series in a power supply circuit, characterized in that the first choke coil is connected to a side closer to the power supply than the second choke coil. It is said that

(Function) In general, the lamp starting voltage is much higher than that of an AC power source, and even a configuration in which the voltage generated in the first choke coil is applied to the discharge lamp via the second choke coil causes almost no problems. There isn't. Therefore, in the present invention, the first choke coil is connected closer to the power source than the second choke coil, and the lamp starting voltage is generated by directly obtaining power from the AC power source, thereby simplifying the pulse generation circuit. .

(Embodiment) FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and the same reference numerals as in FIG. 2 indicate the same elements. The difference from FIG. 2 is that the main choke coil 3 is connected to the AC power source 6 side rather than the auxiliary choke coil 5, and that a pulse generating circuit 7 whose configuration is significantly simplified compared to the pulse generating circuit 2 is used. There is.

Here, the pulse generating circuit 7 is a series circuit of a capacitor 71 and a triac 72, one end of which is connected to the center tap of the main choke coil 3, and the other end connected to the other end of the AC power source 6.

According to this configuration, the AC power supply 6 and the main choke coil 3
, a capacitor 71 and a triac 72 form a closed circuit, and the capacitor 71 connects to the auxiliary choke coil 5.
It is charged without going through. Therefore, the influence of the impedance of the auxiliary choke coil on the pulse waveform can be reliably avoided, and at the same time, the configuration of the pulse generation circuit can be significantly simplified since only one capacitor is required for charging and discharging.

〔Effect of the invention〕

As is clear from the above description, according to the present invention,
A first choke coil that generates a lamp starting voltage,
Since it is connected to the power supply side of the second choke coil for phase control, there is an effect that the configuration of the pulse generation circuit can be significantly simplified.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a circuit diagram showing the configuration of a conventional discharge lamp ballast. 3... Main chiyoke coil, 4... Triac, 5
... Auxiliary choke coil, 7... Pulse generation circuit. Applicant's agent Sato - Engraving of the drawings (no changes to the contents) Figure 1 Figure 2 Procedure Neichi Masago H October 31, 1985

Claims (1)

[Claims] A power supply circuit includes a first choke coil that generates a lamp starting voltage by passing a pulsed current, and a second choke coil that has a triac connected in parallel and that controls the triac to keep the lamp voltage approximately constant. 1. A discharge lamp ballast inserted in series with a discharge lamp, wherein the first choke coil is connected closer to the power source than the second choke coil.