JPH1027693A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically relight a discharge lamp without recharging a power supply when the discharge lamp goes off because instantaneous failure by resetting a timer for a high voltage pulse circuit during lighting. SOLUTION: When a switch 1 is charged, a timer 2 is activated into an ON state to close a switch circuit 3. An oscillation circuit formed with a capacitor 4 and a choke 5 generates pulse to apply high voltage pulse stepped up by the choke 6 to a discharge lamp 7. When the discharge lamp 7 is lit, a lamp current detection circuit 8 opens a switch circuit 3 to stop the high voltage pulse. When the discharge lamp 7 is not lit because it is damaged or its life runs out, the timer 2 stops the high voltage pulse after a preset time, 30 minutes, e.g. passed. When the discharge lamp 7 is then lit, the lamp current detection circuit 8 holds the timer 2 in a set condition. When the discharge lamp 7 goes off because of instantaneous failure, a power is recovered and then the switch circuit 3 is closed to generate the high voltage pulse so that the discharge lamp 7 can be lit again when cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device such as a metal halide lamp which requires a high pressure pulse at the time of starting.

2. Description of the Related Art Discharge lamps, such as metal halide lamps,
When the discharge lamp is cold, the lamp is turned on when a high-voltage pulse is applied for several seconds. However, when the discharge lamp is turned on once and becomes hot, the mercury vapor pressure rises, so that it takes tens of minutes to restart. Accordingly, during this time, a high-voltage pulse is applied until the discharge lamp is turned on again. Also, if the discharge lamp is damaged or its life is expired, the discharge lamp will not be turned on, so that the high-voltage pulse is applied until the power is turned off. If you keep this state for a long time,
The high voltage pulse may deteriorate the insulation of the lighting device coil and the like, and may cause electric shock when a person touches the lighting equipment. Therefore, recently, a timer circuit for controlling the generation time of the high-voltage pulse is built in, so that the high-voltage pulse is not generated about 30 minutes after the power is turned on. To generate the high-voltage pulse again, it is necessary to turn on the power again.

However, in such a conventional method, the discharge lamp goes out if the power is momentarily interrupted 30 minutes or more after the power is turned on. And after power on 3
Since 0 minutes or more have elapsed, even if the discharge lamp is turned off, no high-voltage pulse is generated, and thus the discharge lamp does not turn on. In order to turn on the discharge lamp, it is necessary to turn off the power once and then turn it on again. However, once the power supply is turned off, the other discharge lamps connected to the same power supply also go out, and even if the power supply is turned on again, it takes several tens of minutes until the discharge lamp is in a high temperature state. The present invention has been made in view of the above problems, and proposes a method of turning on a discharge lamp that has been turned off again without turning off the power even when the discharge lamp is turned off due to an instantaneous power failure or the like.

When the discharge lamp is lit, a lamp current flows through the discharge lamp. Therefore, the current is detected, and the timer circuit is constantly maintained in a reset state while the discharge lamp is lit by the detection signal.

When the discharge lamp goes out due to an instantaneous power failure while the discharge lamp is turned on, the timer circuit is reset when the discharge lamp is turned on. A high pressure pulse is generated (about 30 minutes). Since the discharge lamp is in a high temperature state, it takes several tens of minutes to cool down, but the discharge lamp is turned on in about 15 minutes.

FIG. 1 shows an embodiment of the present invention. In the figure, when the switch 1 is turned on, a voltage is applied to the timer circuit 2, the output of the timer is turned on, and the switch circuit 3 operates. Switch circuit 3, capacitor 4, and choke 5
Is formed, and the pulse voltage generated in the choke 5 is boosted by the choke 6 to become a high-voltage pulse and the discharge lamp 7
Is applied to When the discharge lamp 7 is turned on, the switch circuit 3 is turned off by the lamp current detection circuit 8, and the generation of the high voltage pulse is stopped. At the same time, the lamp current detection circuit 7 holds the timer circuit 3 in a reset state. When the discharge lamp 7 is turned off due to an instantaneous power failure or the like, the timer circuit 3 is in the reset state, the switch circuit 3 operates, a high-voltage pulse is applied to the discharge lamp 7, and the discharge lamp 7 is turned on again when it cools down. When the discharge lamp 7 is not turned on, the lamp current does not flow, and the lamp current detection circuit 8 does not operate, so that the timer circuit 3 is not reset. As a result, when the discharge lamp 7 is not lit, the high-voltage pulse is generated for a predetermined time (normally about 30 minutes) set by the timer circuit 3, but after the predetermined time has elapsed, the generation of the high-voltage pulse is stopped.

As described above, according to the present invention, in a discharge lamp lighting device in which a high-voltage pulse is generated for a predetermined time after power is turned on and the high-voltage pulse is stopped after a predetermined time has elapsed, the discharge lamp goes out due to an instantaneous power failure or the like. However, since a high-voltage pulse is generated again, the effect is great because it is not necessary to keep the discharge lamp off or to turn off the power once and turn it on again as in the related art.

[Brief description of the drawings]

 FIG. 1 is a circuit diagram showing an embodiment of the present invention.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuhisa Nomura 98, Kawachi Sekisui, Oji, Mugi-cho, Kaifu-gun, Tokushima Prefecture 1 Tozai Denko Corporation

Claims (1)

[Claims] 1. A discharge lamp lighting device which generates a high-voltage pulse at the time of starting and applies the high-voltage pulse to a discharge lamp, and a switch circuit for generating a high-voltage pulse and a timer for turning off the switch circuit after a lapse of a predetermined time. A discharge lamp lighting device comprising a circuit, wherein the switch circuit is turned off by a lamp current detection circuit, and the timer circuit is reset when the discharge lamp is turned on.