JP2000012257A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a high voltage generating circuit small, and reduce the generation of noise in polarity inversion of an AC rectangular wave by self- oscillating a resonance circuit with a high frequency generating from a self- oscillating circuit in the start of lighting and applying to a discharge lamp. SOLUTION: In the starting of a discharge lamp 4, a self-oscillating circuit 11 self-oscillates a resonance circuit 31 with a high frequency (for example, about 1 MHz) generated from a high frequency generating circuit 21, high voltage is generated in a capacitor 32, and applied to the lamp 4. When the discharge lamp 4 is lit, the resonance phenomenon of the resonance circuit 31 is eliminated, and self-oscillation stops. After that, the discharge lamp 4 is lit by the power source voltage from an AC rectangular wave generating circuit 3. By using the high frequency, capacities of a current feedback resonance circuit 21, a resonance capacitor 32, and a resonance coil 33 can be made small, and the self-oscillating circuit 11 can be made small. Inductance of each coil and transformer is made low, follow to the AC rectangular wave is made quick, and break off of current in polarity inversion is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device capable of generating a high voltage by a self-excited resonance circuit, in which a high voltage generation circuit for applying a high voltage at the start of lighting of the discharge lamp is reduced. The present invention relates to a discharge lamp lighting device capable of reducing noise generated when an AC rectangular wave is inverted.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a conventional discharge lamp lighting device. In the drawing, reference numeral 1 denotes a booster circuit for boosting a power supply voltage supplied from a DC power supply 2, and 3 denotes a power supply voltage from the booster circuit 1. Is converted into an AC square wave, and an AC square wave generating circuit 5 is applied when the discharge lamp 4 is turned on. The AC square wave generating circuit 5 applies a high voltage at the start of lighting of the discharge lamp 4 based on the AC square wave from the AC square wave generating circuit 3. A high-voltage generating circuit for applying the AC rectangular wave from the AC rectangular wave generating circuit 3 to the coil 5
A high voltage is generated at both ends of the capacitor 5b due to the resonance between a and the capacitor 5b.

Next, the operation will be described. First, at the start of lighting of the discharge lamp 4, the high-voltage generating circuit 5 generates a high voltage at both ends of the capacitor 5b by the resonance between the coil 5a and the capacitor 5b using the AC rectangular wave from the AC rectangular wave generating circuit 3, This high voltage is applied to the discharge lamp 4.
When the discharge lamp 4 is turned on, the AC square wave generating circuit 3 converts the power supply voltage from the booster circuit 1 into an AC square wave and applies the AC voltage to the discharge lamp 4.

In the discharge lamp lighting device that generates a high voltage by the above-described resonance circuit, the AC rectangular wave generation circuit 3 is complicated because the current flowing through the discharge lamp 4 is reduced by the impedance of the coil 5a. . In addition, the lighting frequency becomes about 10 KHz, which may exceed the acoustic resonance phenomenon, and both the coil 5a and the capacitor 5b have a large capacity.

Next, another discharge lamp lighting device will be described. FIG. 6 is a block diagram showing another conventional discharge lamp lighting device. In the drawing, reference numeral 6 denotes a switch which generates a high voltage pulse by using a switch and a transformer 6a to charge an electric charge charged in a capacitor, and outputs the high voltage pulse to an AC square wave generating circuit. This is a high voltage generating circuit to be superimposed. Such a configuration requires a large-capacity capacitor and a secondary coil having high withstand voltage and small inductance. When the inductance of the secondary coil is large, the current is interrupted when the polarity of the AC square wave is inverted,
Immediately after that, an inrush current flows, which may cause noise.

[0006]

Since the conventional discharge lamp lighting device is constructed as described above, it requires a coil 5a and a capacitor 5b for generating a high voltage. There were problems such as inviting an increase in size.

Another problem is that the current is interrupted when the polarity of the AC rectangular wave is inverted, and a large current flows immediately after the polarity inversion to generate noise.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to reduce the size of a high voltage generating circuit for applying a high voltage at the start of lighting of a discharge lamp, and to invert the polarity of an AC rectangular wave. It is an object of the present invention to obtain a discharge lamp lighting device capable of reducing noise that is sometimes generated.

[0009]

In the discharge lamp lighting device according to the present invention, the high voltage generating circuit is constituted by a self-excited oscillating circuit which oscillates at a high frequency to generate a high voltage.

A discharge lamp lighting device according to the present invention uses a current feedback resonance in a self-excited oscillation circuit.

A discharge lamp lighting device according to the present invention uses a voltage feedback resonance in a self-excited oscillation circuit.

In the discharge lamp lighting apparatus according to the present invention, the self-excited oscillation circuit is operated only by the control circuit when the discharge lamp is turned on.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a discharge lamp lighting device according to Embodiment 1 of the present invention.
Is a booster circuit that boosts the power supply voltage supplied from the DC power supply 2, 3 is a power supply voltage from the booster circuit 1, which converts the power supply voltage into an AC square wave, and is applied when the discharge lamp 4 is turned on. This is a self-excited oscillation circuit (high-voltage generation circuit) using feedback resonance. The resonance circuit 31 uses a high frequency (for example, about 1 MHz) generated from the high-frequency generation circuit 21.
Is self-excited and a high voltage is applied to the discharge lamp 4. Since the self-excited oscillation circuit 11 self-oscillates at a high frequency to obtain a high voltage, the capacitor 32 and the coil 33 of the resonance circuit 31 are connected to the capacitor 5b of the conventional discharge lamp lighting device.
In addition, the capacity is smaller than that of the coil 5a (see FIG. 5), so that a smaller one can be used.

Next, the operation will be described. First, at the start of lighting of the discharge lamp 4, the self-excited oscillation circuit 11 self-oscillates the resonance circuit 31 with the high frequency generated from the high frequency generation circuit 21, generates a high voltage on the capacitor 32, and applies the high voltage to the discharge lamp 4. When the discharge lamp 4 is turned on, the resonance phenomenon in the resonance circuit 31 disappears, and the self-excited oscillation stops. Thereafter, the discharge lamp 4 is turned on by the power supply voltage from the AC square wave generation circuit 3.

FIG. 2 is a perspective view showing a state in which the discharge lamp lighting device according to Embodiment 1 of the present invention is incorporated in a connector of a vehicle-mounted discharge lamp. In the figure, reference numeral 41 denotes a base of the discharge lamp 4, reference numeral 42 denotes a connector directly attached to the base 41 of the discharge lamp 4, reference numeral 43 denotes a self-excited oscillation circuit board on which the self-excited oscillation circuit 11 is assembled, and reference numeral 44 denotes an integrated connector with the connector 42. A cover for covering the self-excited oscillation circuit board 43. In this discharge lamp lighting device, the booster circuit 1 and the AC rectangular wave generator 3 can be separated from the self-excited oscillation circuit 11, and therefore, as shown in FIG. A self-excited oscillation circuit board 43 to which only the circuit 11 is attached can be attached. Therefore, the self-excited oscillation circuit board 43 for generating a high voltage as a noise source
And the discharge lamp 4 can be located in the vicinity.

As described above, according to the first embodiment, the self-excited oscillation circuit 11 as a high-voltage generating circuit for applying a high voltage when the discharge lamp 4 is turned on can be reduced. Can be

Further, since the inductance of each coil is low and the current can follow the inversion of the AC voltage applied to the discharge lamp 4 in a short time, the noise generated without interruption of the current at the time of voltage inversion is reduced. And the like.

Embodiment 2 FIG. FIG. 3 is a configuration diagram showing a discharge lamp lighting device according to a second embodiment of the present invention. In the figure, the same reference numerals as those in the first embodiment denote the same or corresponding parts, and a description thereof will be omitted. Reference numeral 51 denotes a self-excited oscillation circuit (high-voltage generation circuit) using voltage feedback resonance, which feeds back an applied voltage and amplifies the voltage to generate a high voltage.

Next, the operation will be described. When a voltage is applied to the self-excited oscillation circuit 51, each of the capacitors 51a,
The voltage is divided and stored in 51b and 51c. Next, the voltage detection circuit 51d detects the voltage applied to the capacitor 51a, amplifies the voltage with the amplifier 51e, and further charges the capacitor. Thereafter, the charging current is inverted to the discharging side after charging due to resonance by the coil 51f. At this time, the amplifier 51e amplifies the voltage divided by the capacitors 51a, 51b, 51c, and discharges the capacitors. Output voltage. As a result, the discharge is promoted to the coil 51f by resonance. Then, the discharge current is inverted to the charging side due to the resonance of the coil 51f, and the amplifier 51e outputs a voltage in a charging direction. By repeating the above resonance operation, the coil 51f and the capacitor self-oscillate, and a high voltage is generated in the capacitor. Then, this high voltage is applied to the discharge lamp 4.

In the voltage feedback resonance, a piezoelectric element transformer using a piezoelectric element may be used instead of the capacitors 51a, 51b and 51c.

As described above, according to the second embodiment, the self-excited oscillation circuit 51 as a high voltage generating circuit for applying a high voltage at the start of lighting of the discharge lamp 4 can be reduced, Since the impedance of the coil is low and the current can follow the reversal of the AC voltage applied to the discharge lamp 4 in a short time, the current is not interrupted at the time of the voltage reversal, and the generated noise can be reduced. Is obtained.

Embodiment 3 FIG. FIG. 4 is a configuration diagram showing a discharge lamp lighting device according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in Embodiments 1 and 2 denote the same or corresponding parts, and a description thereof will be omitted. 61
Is a self-excited oscillation circuit (FIG. 1) only when the discharge lamp 4 starts lighting.
11 or 51) 62 of FIG. As described above, according to the third embodiment, since the self-excited oscillation circuit is operated only at the start of lighting of the discharge lamp 4, effects such as preventing unnecessary high voltage from being applied to the discharge lamp 4 can be obtained. Is obtained.

[0023]

As described above, according to the present invention, the high-voltage generating circuit is composed of a self-excited oscillation circuit that generates a high voltage by self-oscillation at a high frequency. Can be reduced, and the noise generated when the AC voltage is inverted can be reduced.

According to the present invention, since the self-excited oscillation circuit is configured to use current feedback resonance, it is possible to reduce the size of the high voltage generating circuit for applying a high voltage at the start of lighting of the discharge lamp, This has the effect of reducing the noise generated at the time of inversion of.

According to the present invention, since the self-excited oscillation circuit is configured to use the voltage feedback resonance, it is possible to reduce the size of the high voltage generating circuit for applying the high voltage at the start of lighting of the discharge lamp, and This has the effect of reducing the noise generated at the time of inversion of.

According to the present invention, the control circuit operates the self-excited oscillation circuit only at the start of lighting of the discharge lamp. Therefore, it is possible to reduce the size of the high voltage generating circuit for applying a high voltage at the time of lighting of the discharge lamp. This can reduce noise generated at the time of inversion of the AC voltage, and can prevent application of an unnecessary high voltage to the discharge lamp.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a discharge lamp lighting device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which the discharge lamp lighting device according to the first embodiment of the present invention is incorporated in a connector of a vehicle-mounted discharge lamp.

FIG. 3 is a configuration diagram illustrating a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a discharge lamp lighting device according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional discharge lamp lighting device.

FIG. 6 is a configuration diagram showing another conventional discharge lamp lighting device.

[Explanation of symbols]

1 booster circuit, 3 AC square wave generation circuit, 4 discharge lamp, 11, 51, 62 self-excited oscillation circuit (high voltage generation circuit), 61 control circuit.

Claims (4)

[Claims] 1. An AC square wave generating circuit for applying an AC square wave at the time of lighting of a discharge lamp, and a high voltage for applying a high voltage at the start of lighting of the discharge lamp based on the AC square wave from the AC square wave generating circuit. A discharge lamp lighting device comprising a voltage generation circuit, wherein the high voltage generation circuit is constituted by a self-excited oscillation circuit that generates a high voltage by self-oscillation at a high frequency. 2. The discharge lamp lighting device according to claim 1, wherein the self-excited oscillation circuit is a current feedback resonance circuit. 3. The discharge lamp lighting device according to claim 1, wherein the self-excited oscillation circuit is a voltage feedback resonance circuit. 4. The discharge lamp lighting device according to claim 1, further comprising a control circuit for operating the self-excited oscillation circuit only when the discharge lamp starts lighting.