JPH0123919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flash device capable of continuously flashing light.

Conventionally, this type of flash device charges a main capacitor installed in parallel with the flash discharge tube via a charging resistor, and supplies the charged charge of the main capacitor as flash energy to the flash discharge tube to generate a flash. . Since the flash interval is determined by the capacitance of the main capacitor and the resistance value of the charging resistor, it is necessary to reduce the capacitance of the main capacitor and the charging resistor in order to shorten the flash interval. However, if the resistance value of the charging resistor is made extremely small,
Flash discharge tubes have the disadvantage that continuous discharge occurs after the flash, making continuous flash impossible.

The present invention has been proposed in view of the above, and an object of the present invention is to provide a flash device capable of continuous flashing by shortening the flash interval.

The embodiments shown in the drawings will be described below. A power supply 1, a resistor 2, a diode 3, and a capacitor 4 are connected in series. A series circuit of a resistor 8 and a capacitor 9 is provided in parallel with the capacitor 4, and a flash discharge tube 10 is connected in parallel with the resistor 8. Further, the capacitor 9 is provided in parallel with a series circuit of a thyristor 6 and an inductance 7, and a series circuit of a diode 11, a resistor 12, and a constant voltage diode, that is, a Zener diode 13. A delay circuit including a resistor 14 and a capacitor 15 connected in series is connected to the Zener diode 13 in parallel. Reference numeral 16 denotes a gate resistor of the thyristor 18, which has a sufficiently larger resistance value than the resistor 14 described above. The thyristor 18 has a gate connected to a connection point between a resistor 14 and a capacitor 15 forming a delay circuit,
Together with a resistor 17, a trigger capacitor 19, and a trigger transformer 20, it constitutes a known flash discharge tube trigger circuit. Reference numeral 21 designates a known oscillation circuit as a signal generator for supplying a conductive signal to the thyristor 6, and supplies an oscillation output to the gate of the thyristor 6 while the switch 22 is closed.

Now, the capacitor 4 is charged by the power source 1 via the resistor 2 and the diode 3, and the capacitor 9 is charged via the resistor 2, the diode 3, and the resistor 8, respectively. When the oscillation output of the oscillation circuit 21 is applied to the gate of the thyristor 6, the thyristor 6 becomes conductive and discharges the charge stored in the capacitor 9 via the inductance 7. At this time, the inductance 7, the thyristor 6, and the capacitor 9 constitute a resonant circuit, so the capacitor 9
The voltage changes to the opposite polarity to the previously charged polarity. However, since the thyristor 6 is a one-way conductive element, it does not return to the pre-charged voltage again and is maintained at an inverted polarity. Since the polarity of the charging voltage of the capacitor 9 has been reversed, the charge is discharged through the Zener diode 13, the resistor 12, and the diode 11, and a Zener voltage is generated at both poles of the Zener diode 13. Therefore, the capacitor 15 connected in parallel to the Zener diode 13 is charged via the resistor 14, and when the charging voltage exceeds the gate-cathode voltage of the thyristor 18, the thyristor 18 becomes conductive. The trigger circuit is activated by conduction of the thyristor 18.
That is, the charge in the trigger capacitor 19 charged via the resistor 17 is discharged via the thyristor 18 and the primary winding of the trigger transformer 20, and a high frequency high voltage is generated in the secondary winding of the trigger transformer. Therefore, the flash discharge tube 10 is ionized,
The charge in the capacitor 4 is discharged via the flash discharge tube 10 and the capacitor 9 to emit a flash. The discharge current of the flash discharge tube 10 charges the charged capacitor 9 with the reversed polarity as described above, and becomes the same polarity as the pre-charged voltage polarity, and is discharged when the charging voltage of the capacitor 9 reaches almost the voltage of the capacitor 4. stops and the flash also stops.

After the above operation is completed, when the oscillation output from the oscillation circuit 21 is given to the gate of the thyristor 6 again, the capacitor 9 is charged to the polarity before the switch 22 was closed, so the same operation as above is performed. be exposed. Therefore, when the oscillation output from the oscillation circuit 21 is thereafter applied to the gate of the thyristor 6, the above operation is repeated.

As mentioned above, the thyristor 6 is made conductive by the oscillation output of the oscillation circuit 21, and the
Then, the charging voltage polarity of the capacitor 9 is reversed using a resonance circuit. Then, by activating a delay circuit having a delay time of several microseconds to several tens of microseconds, which is longer than the turn-off time of the thyristor 6 that operates in response to the reversal, a known flash discharge is generated after the thyristor becomes non-conductive again. Activate the tube trigger circuit. Therefore, the discharge current of the flash discharge tube 10 from the capacitor 4 does not flow through the inductance 7 and the thyristor 6, and the capacitor 9 is charged to the polarity just before the thyristor 6 was turned on, so that it can immediately prepare for the next flash. Therefore, it is possible to shorten the flash interval, which has been difficult in the past.

In addition, by setting the capacitance value of capacitor 4 sufficiently larger than that of capacitor 9, the capacitor 4 due to the charging current of capacitor 9 during flashing can be
It is possible to emit light with a stable amount of light with a small voltage drop, and even when operated with only the charge of the capacitor 4, multiple flashes of light are possible.

As described above, the present invention provides a second
After reversing the polarity of the capacitor prior to flash emission, when the charge in the first capacitor is discharged through the flash discharge tube and the second capacitor to cause the flash discharge tube to emit light, the polarity of the flash discharge tube is Using the discharge current, the second capacitor is charged to the same polarity as before the flash activation and to approximately the same voltage as the charging voltage of the first capacitor, in preparation for the next flash emission. Therefore, after the flash is emitted, the second capacitor can be charged without going through the charging resistor, and the flash interval can be shortened without reducing the resistance value of the charging resistor. This makes it possible to emit flash light continuously and continuously.

[Brief explanation of drawings]

The drawing is an electrical circuit diagram of the flash device of the present invention. 1 is a power supply, 4 is a first capacitor, 6 is a switch element, 7 is an inductance, 9 is a second capacitor, 10 is a flash discharge tube, and 21 is a signal generator.

Claims (1)

[Claims] 1. A first capacitor connected in parallel with a power supply, a series body of a resistor and a second capacitor connected in parallel with the first capacitor, a flash discharge tube connected in parallel with the resistor, and a series body connected in parallel with the second capacitor. a series resonant circuit of an inductance and a thyristor; a delay circuit that operates due to conduction of the thyristor and generates an output after a predetermined time period longer than the time required for the thyristor to turn off;
It has a trigger circuit that triggers the flash discharge tube in response to the output of the delay circuit, and a signal circuit that supplies a signal for making the thyristor conductive.
The second capacitor is charged in advance through the resistor connected in series with the capacitor, and the second capacitor is charged in advance through the flash discharge tube during the previous light emission for the next light emission. A flash device that can flash continuously.