JPH0612715B2 - Flash lamp trigger method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flash lamp triggering method, and more particularly to P.
The present invention relates to a flash lamp trigger system using an FN (pulse forming circuit).

As a trigger method for a conventional flash lamp, as shown in FIG. 1, a series trigger method in which a high voltage pulse is applied between both electrodes of the flash lamp 5 and one of the flash lamp 5 as shown in FIG. There is an external trigger method in which a high voltage pulse is applied to a conductor portion in the vicinity of the flash lamp 5 with respect to the electrode. In both figures, the same parts are denoted by the same reference numerals, 1 is a large capacity DC power supply, 2 is a PFN in which capacitors and choke coils are connected in multiple stages, in order to give flexibility to the configuration of this PFN. The external trigger method shown in FIG. 2 is generally used.

However, in these two methods, so-called misflash may occur in which the flash lamp 5 does not flash even if a high voltage trigger pulse is applied from the trigger circuit 3 via the trigger transformer 4. In particular, when a plurality of flash lamps are connected in series, or when the internal pressure of an inert gas such as xenon gas or krypton gas inside the flash lamps is high, the occurrence rate of misflash tends to increase.

This misflash occurs on the following principle. That is,
The ionized part of the inert gas inside the flash lamp generated by the high-voltage trigger pulse is transmitted through the inner wall of the glass of the flash lamp and is observed as a streamer (fire wire). However, this streamer is unstable and its impedance is high, so the PFN The electric charge stored in the flash lamp does not discharge to the flash lamp, which causes a misflash.

SUMMARY OF THE INVENTION Therefore, the present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a reliable trigger method for a flash lamp by removing the cause of a misflash. Especially.

Configuration of the Invention The trigger method of the flash lamp according to the present invention is PFN.
The auxiliary flash circuit having a sufficiently high generated voltage with respect to the generated voltage is provided in parallel with this PFN so that the generated voltage of the auxiliary flash circuit can be discharged through the ionized gas in the flash lamp by the trigger voltage. Is characterized by.

Principle of the Invention Thus, by providing another small-capacity auxiliary flash circuit that generates a voltage sufficiently higher than the generated voltage of the PFN in parallel with the PFN, the charge accumulated in this auxiliary flash circuit is triggered by the high voltage trigger. The pulse will slowly discharge through the ionized gas produced in the flash lamp. This discharge lowers the impedance of the flash lamp sufficiently, so that the electric charge stored in the PFN can be discharged to the flash lamp, and the misflash is effectively eliminated.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a circuit diagram of an embodiment of the present invention, and the same portions as those in FIGS. 1 and 2 are designated by the same reference numerals. In the figure, the portion indicated by the dotted line 20 is the auxiliary flash circuit of the present invention. A small-capacity DC power supply 6 is provided, and this voltage is sufficiently higher than that of the power supply 1. The electric charge generated by the power source 6 is stored in the capacitor 7 and is passed through the current limiting resistor 8 and the backflow prevention diode 9 to the flash lamp 5
Is applied in parallel with the output voltage of PFN2. A pulse generator 10 for generating a flash command signal is provided, and the trigger circuit 3 operates in response to this command pulse. The output pulse of the pulse generator 10 becomes a gate control signal of the SCR 12 via the delay device 11. The SCR 12 and the diode 1 provided in series therewith
3 is for withstand voltage protection of the capacitor of PFN2, and P is connected through the series circuit of this SCR12 and diode 13.
The output voltage of FN2 is applied to the flash lamp 5.

In such a configuration, the capacitor 7 is charged to a voltage sufficiently higher than the output voltage of the PFN 2 by the high voltage DC power supply. This charging voltage is applied to the flash lamp 5 via the diode 9, but the generated voltage of the PFN 2 is not applied to the flash lamp 5 because the SCR 12 is off.

When a flash command signal is generated from the pulse generator 10 in this state, a trigger pulse is generated from the trigger voltage generation circuit 3, the trigger voltage is boosted by the trigger transformer 4, and the high voltage trigger pulse is applied to the flash lamp 5.
Therefore, the interior of the flash lamp 5 is ionized, so that the electric charge stored in the capacitor 7 is gently passed through the current limiting resistor 8 and the diode 9.
And the impedance of the flash lamp 5 becomes sufficiently low. On the other hand, since the pulse of the pulse generator 10 becomes the gate signal of the SCR 12 via the delay device 11, the SCR 12 is turned on when the impedance of the flash lamp 5 becomes sufficiently low, and the large capacity DC power supply 1 The electric charge of the PFN 2 charged by is applied to the flash lamp 5. Therefore, the flash lamp is surely discharged without misfiring. The discharge current of the PFN is blocked by the backflow prevention diode 9.

In the above embodiment, the SCR is provided when the delay device 11 is provided and the low impedance of the flash lamp is sufficiently low.
Is turned on to apply the voltage of PFN to the flash lamp, but this delay device may be omitted in some cases. The current limiting resistor 8 may be replaced with a choke coil.

EFFECTS OF THE INVENTION According to the present invention, an auxiliary flash circuit having a small capacity and a high voltage is provided in parallel with the PFN so as to reduce the impedance of the flash lamp by the voltage of the auxiliary flash circuit. The discharge of the lamp becomes reliable, and a reliable trigger method can be obtained without causing a misflash. In particular, it is effective when the number of flash repetitions is small and can be downsized as compared with the conventionally known so-called simmer current circuit.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are circuit diagrams showing a conventional flash lamp trigger system, and FIG. 3 is a circuit diagram of an embodiment of the present invention. Explanation of symbols of main parts 1 ... Large capacity DC power supply, 2 ... PFN 3 ... Trigger circuit 5 ... Flash lamp 6 ... Small capacity DC power supply, 7 ... Capacitor 10 ... Pulse generator, 11 ... Delay device 12 ... SCR

Claims (1)

[Claims] 1. A flash lamp triggering method using a pulse forming circuit, wherein the auxiliary flash circuit is provided in parallel with the pulse forming circuit and has a sufficiently high generated voltage with respect to the generated voltage of the pulse forming circuit. A pulse generator for generating a flash command signal, a delay means for delaying an output pulse of the pulse generator, and a switching means for performing an on / off operation with an output signal from the delay means are provided. The voltage generated by the auxiliary flash circuit via ionized gas is slowly discharged by a time constant circuit, and when the impedance of the flash lamp becomes sufficiently low, the switching means is turned on by a signal from the delay means, The output of the pulse forming circuit Flash lamp trigger method, which comprises applying to the serial flash lamp.