JPH0645078A - Quick lighting ballast circuit and quick lighting device for metal halide lamp - Google Patents

Abstract

PURPOSE:To prevent the reduction in illuminance caused by long time use by feeding back the secondary coil output of a transformer to a pulse current amplifying circuit to make the secondary coil output current value constant. CONSTITUTION:When an abnormal current control thyristor 3 and a thermal switch diode 4 which are different in properly used voltage range are used, two transformers 51, 52 for voltage and matching are provided, and the secondary side of the transformer 52 is connected to a metal halide lamp 6. Further, the secondary side output of the transformer 52 is fed back 7 to a pulse current amplifying circuit 2, and the output of the circuit 2 is increased and decreased to make the secondary side output current of the transformer 52 constant. Thus, when electrodes are worn by the long time use of the lamp 6, and the distance between electrodes is increased to reduce the current, the output voltage of the circuit 2 is raised, a voltage higher than the voltage in initial stage of use is added to the lamp 6 to make the current constant, and a constant illuminance can be kept.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ballast circuit and a device capable of quickly turning on a metal halide lamp and maintaining a constant illuminance for a long time.

[0002]

2. Description of the Related Art Metal halide lamps have excellent characteristics, but have a drawback in that the discharge stable voltage is around 90 V, but the discharge start voltage is high at around 240 V, and it takes a long time to light. Further, when used for a long time, the electrodes are consumed and the distance between the electrodes increases, so that the current decreases and the illuminance decreases.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of metal halide lamps and enables rapid lighting, and a ballast circuit for rapid lighting of metal halide lamps that can maintain a constant illuminance for a long time. The purpose is to provide.

[0004]

A ballast circuit for rapid lighting of a metal halide lamp according to the present invention comprises a pulse current generating circuit, a pulse current amplifying circuit, and an output of the amplifying circuit through an abnormal current control thyristor and a thermal switch diode. And a circuit for connecting the output of the secondary coil of the transformer to the metal halide lamp, and the output of the secondary coil of the transformer is fed back to the pulse current amplification circuit to output the secondary coil of the transformer. It is characterized in that the output voltage of the pulse current amplifier circuit is increased or decreased so that the current value becomes constant.

However, since the abnormal current control thyristor and the thermal switch diode which are currently on the market and put into practical use have different proper operating voltage ranges, in that case, a ballast circuit for rapid lighting of a metal halide lamp, a pulse current generating circuit, A pulse current amplifier circuit, a circuit for connecting the output of the amplifier circuit to the primary coil of the first transformer through the abnormal current control thyristor, and the output of the secondary coil of the first transformer through the thermal switch diode for the second transformer. A circuit for connecting to the primary coil and a circuit for connecting the output of the secondary coil of the second transformer to the metal halide lamp is provided, and the output of the secondary coil of the second transformer is fed back to the pulse current amplifying circuit to output the second current. Pulse current so that the output current value of the secondary coil of the transformer is constant It may be configured to increase or decrease the output voltage of the width circuit.

The first invention (claim 1) will be described with reference to FIG. 1. In this invention, a pulse current generating circuit 1, a pulse current amplifying circuit 2, an output of the amplifying circuit is an abnormal current control thyristor 3 and a thermal switch diode 4 are provided. And a circuit for connecting the output of the secondary coil of the transformer 5 to a metal halide lamp through the circuit of the transformer 5 and feeding back (7) the output of the secondary coil of the transformer 5 to the pulse current amplification circuit. Trance 5
The output voltage of the pulse current amplifier circuit 2 is increased or decreased so that the output current value of the secondary coil becomes constant.

The second invention (claim 2) will be described with reference to FIG. 2. In the present invention, the pulse current generating circuit 1, the pulse current amplifying circuit 2, and the output of the amplifying circuit are passed through an abnormal current control thyristor 3 to obtain the first invention. A circuit connecting the primary coil of the transformer 51, a circuit connecting the output of the secondary coil of the first transformer 51 to the primary coil of the second transformer 52 via the thermal switch diode 4, and a secondary coil of the second transformer 52. The output current of the secondary coil of the second transformer 52 by feeding back (7) the output of the secondary coil of the second transformer to the pulse current amplifier circuit. Is configured so that the output voltage of the pulse current amplifier circuit 2 is increased or decreased so as to be constant.

The mechanism of action is the same in both cases. The thermal switch diode 4 heats itself when a current flows, and as a result, the resistance value increases. When the resistance value of the thermal switch diode increases, the voltage applied to the primary coil of the transformer 5 or 51 decreases, and as a result, the output voltage of the secondary coil decreases. For example, transformer 5 or 5
If the impedance of the primary coil of 1 is AΩ, the resistance value of the thermal switch diode is 0Ω at room temperature, and the maximum is BΩ at high temperature, the transformer 5 or 5 can be used for the first lighting.
While the total voltage is applied to one primary coil, the voltage applied to the primary coil at high temperature is A / (A + B). If this ratio is set to 90/240, the output voltage of the secondary coil also becomes 90/240. The step-up ratio of the transformer 5 or 51 may be set so that the thermal switch diode 4 can be used within its proper operating voltage range.

When the appropriate operating voltages of the abnormal current control thyristor 4 and the thermal switch diode 5 are the same, they can be used by directly connecting them as shown in FIG. 1, and if an element integrating both functions is developed. It may be used, but since the appropriate operating voltage range is different between the abnormal current control thyristor and the thermal switch diode which are currently on the market and put into practical use, in that case, as shown in FIG.
As shown in Fig. 2, two transformers 51 and 52 are used to output the output of the current amplification circuit to the first through an abnormal current control thyristor.
Circuit for connecting to the primary coil of the transformer, a circuit for connecting the output of the secondary coil of the first transformer to the primary coil of the second transformer through the thermal switch diode, and a metal halide output of the secondary coil of the second transformer. A circuit connected to the lamp is provided so that the output voltage of the current amplifier circuit is within the proper operating voltage range of the abnormal current control thyristor and the output voltage of the secondary coil of the first transformer 51 is within the proper operating voltage range of the thermal switch diode. Just set it.

When the light is turned off once and then turned on, the thermal switch diode remains at high temperature.
The metal halide lamp has a stable discharge voltage (9
Only about 0V) can be applied, but since the metal halide lamp remains at a high temperature immediately after it is turned off, it is lit at the stable discharge voltage (about 90V).

Further, in the present invention, the transformer 5 or 5
The output of the secondary coil of No. 2 is fed back (7) to the pulse current amplification circuit to increase or decrease the output voltage of the pulse current amplification circuit so that the output current value of the secondary coil of the transformer 5 or 52 becomes constant. Since the metal halide lamp is used for a long period of time, if the electrode wears out and the distance between the electrodes increases and the current decreases, the output voltage of the pulse current amplifier circuit rises, resulting in a metal halide lamp. Since a voltage higher than the initial voltage is applied and the current is kept constant, a constant illuminance can be maintained.

In order to achieve the purpose of quickly turning on the metal halide lamp and maintaining constant illuminance for a long time,
The frequency of the pulse current is not particularly limited, but considering that the metal halide lamp is used for illumination during video recording, it is desirable that the frequency of the pulse current is a multiple of 60 Hz / S, especially 3 times or more. That is, since the video camera shoots at 60 Hz / S, if the light emission cycle of the metal halide lamp for illumination is different from that, the illuminance of the screen to be shot changes, causing flicker on the reproduced screen. Even if the light emission cycle is 60 Hz / S,
If the synchronization is deviated, the lighting will not be used effectively and the screen will be dark. Therefore, the frequency of the pulse current, that is, the light emission period is 60H.
If it is a multiple of z / S, the screen to be photographed is always illuminated with the same number of emitted lights, and flicker and illuminance reduction are prevented.

As another means for keeping the illumination constant during video recording, a circuit and an external circuit for synchronizing (external trigger interlock) a pulse current generating circuit with an external device operating at 60 Hz / S. It may have a connection terminal.

By using the ballast circuit having the above structure, the time required for lighting the metal halide lamp can be shortened to about 2 seconds. To further shorten the time, for example, within 1 second, refer to FIG. 3 or FIG. As shown, the piezoelectric element 8 is provided in parallel with the metal halide lamp in the circuit connecting the output of the secondary coil of the transformer 5 or 52 to the metal halide lamp 6, and a pulse current is supplied to the metal halide lamp to perform the lighting operation. A device for rapid lighting of a metal halide lamp configured to give an impact to the piezoelectric element at the time of performing may be used.

As the piezoelectric element, one having an electromotive force of 6 to 12 KV is preferably used. It has been found that, when a pulse current is supplied to the metal halide lamp to perform a lighting operation, when the piezoelectric element is impacted, the above voltage and a pulse of 6 to 12 KHz are supplied. As a result, the lighting time of the metal halide lamp is further shortened.

[0016]

EFFECTS OF THE INVENTION The metal halide lamp solves the drawbacks of the metal halide lamp that it takes a long time to light and the illuminance decreases when it is used for a long time, and it is possible to quickly light and maintain a constant illuminance for a long time. The usage area of can be expanded.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a configuration of a ballast circuit of the present invention.

FIG. 2 is a diagram for explaining another configuration of the ballast circuit of the present invention.

FIG. 3 is a diagram for explaining a configuration of a quick lighting device of the present invention.

FIG. 4 is a diagram for explaining another configuration of the quick lighting device of the present invention.

Claims (6)

[Claims] 1. A pulsed current generation circuit, a pulsed current amplification circuit, a circuit for connecting the output of the amplification circuit to a primary coil of a transformer through an abnormal current control thyristor and a thermal switch diode, and an output of a secondary coil of the transformer to a metal halide lamp. The output voltage of the secondary coil of the transformer is fed back to the pulse current amplification circuit to increase or decrease the output voltage of the pulse current amplification circuit so that the output current value of the secondary coil of the transformer becomes constant. A ballast circuit for quick lighting of a metal halide lamp, which is configured as described above. 2. A pulse current generating circuit, a pulse current amplifying circuit, a circuit for connecting the output of the amplifying circuit to a primary coil of a first transformer through an abnormal current control thyristor, and an output of a secondary coil of the first transformer. It has a circuit for connecting to the primary coil of the second transformer through a thermal switch diode and a circuit for connecting the output of the secondary coil of the second transformer to the metal halide lamp, and the output of the secondary coil of the second transformer is The output voltage of the pulse current amplification circuit is increased or decreased by feeding back to the pulse current amplification circuit so that the output current value of the secondary coil of the second transformer becomes constant. Ballast circuit for quick lighting. 3. The ballast circuit for rapid lighting of a metal halide lamp according to claim 1, wherein the pulse current generating circuit generates a pulse of a multiple of 60 Hz / S. 4. The rapid lighting of the metal halide lamp according to claim 1, wherein the pulse current generation circuit has a circuit for synchronizing with an external device operating at 60 Hz / S and an external connection terminal. Ballast circuit. 5. A pulsed current generation circuit, a pulsed current amplification circuit, a circuit for connecting the output of the amplification circuit to the primary coil of the transformer through an abnormal current control thyristor and a thermal switch diode, and the output of the secondary coil of the transformer to a metal halide lamp. The output voltage of the secondary coil of the transformer is fed back to the pulse current amplification circuit to increase or decrease the output voltage of the pulse current amplification circuit so that the output current value of the secondary coil of the transformer becomes constant. The piezoelectric element is provided in parallel with the metal halide lamp in the circuit that connects the output of the secondary coil of the transformer to the metal halide lamp, and supplies a pulse current to the metal halide lamp to turn it on. It is designed to give an impact to the piezoelectric element during operation. A device for quick lighting of metal halide lamps characterized by. 6. A pulse current generating circuit, a pulse current amplifying circuit, a circuit for connecting the output of the amplifying circuit to a primary coil of a first transformer through an abnormal current control thyristor, and an output of a secondary coil of the first transformer. It has a circuit for connecting to the primary coil of the second transformer through a thermal switch diode and a circuit for connecting the output of the secondary coil of the second transformer to the metal halide lamp, and the output of the secondary coil of the second transformer is The output voltage of the pulse current amplifier circuit is increased or decreased by feeding back to the pulse current amplifier circuit so that the output current value of the secondary coil of the second transformer becomes constant. A piezoelectric element is provided in parallel with the metal halide lamp in the circuit that connects the output of the next coil to the metal halide lamp. A device for rapid lighting of a metal halide lamp, characterized in that the piezoelectric element is impacted when a lighting operation is performed by supplying a pulse current to the metal halide lamp.