JPS6392936A - Stroboscopic device - Google Patents

Abstract

PURPOSE:To prevent a flash discharge tube from continuous discharge by providing the titled device with a charge command means for forcedly releasing the inhibition of charge to the 2nd capacitor by a charge control means only for a prescribed period from the detection of charging voltage drop by a detecting means. CONSTITUTION:At the time of detecting that a charging voltage to a light emission starting capacitor 10 reaches a fixed voltage or less, a transistor (TR) 18 is held at its ON state by a time constant circuit consisting of a capacitor 19 and a resistor 15 during the period from the start of flashing up to the disappearance of Xe ions, a thyrister 8 is turned on and charge to a flashing capacitor 11 is executed simultaneously with the charge to the capacitor 10 during the period. Since the charging voltages of both the capacitors 11, 10 are not suddenly boosted, the Xe tube 19 can be prevented from continuous discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in a strobe device equipped with a small-capacity light emission starting capacitor and a large-capacity flash light emission capacitor.

(Background of the Invention) Conventionally, in addition to a normal flashlight emission capacitor, a light emission activation capacitor that is charged first has been provided, and it is possible to instantly charge the flashlight emission capacitor even before charging is completed. By using the charged charge of the light emission activation capacitor for light emission activation, it is compatible with quick shooting. Strobe devices that enable stable photography have been proposed.

In this way, in a device that starts charging the flashlight emission capacitor after charging the light emission starting capacitor to the light emission starting voltage, the voltage of the light emission starting capacitor also changes when the flash fires. ), charging of the light emission starting capacitor immediately starts. At this time, the voltage across the Xe tube is the emission final voltage, but since Xe ions remain, the charging energy for the emission starting capacitor flows through the Xe tube, and there is a risk of causing sustained discharge. Ta.

(Object of the Invention) An object of the present invention is to provide a strobe device that can prevent sustained discharge of a flash discharge tube and prepare for the next flash emission.

(Characteristics of the Invention) In order to achieve the above object, the present invention provides charging that forcibly releases the prohibition of charging to the second capacitor by the charging control means for a predetermined period after the charging voltage drop is detected by the detection means. Establish a means of command.

Therefore, by detecting a drop in the charging voltage of the first capacitor due to flash emission, the first and second capacitors are charged in parallel until a predetermined period of time has elapsed, and during this period, the first capacitor is charged in parallel. is characterized in that charging is not performed instantaneously.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which 1 is a battery as a power source, 2 is a power switch, 3 is a known DC/DC converter for boosting battery voltage, and 4 to 7 are 8 is a thyristor, 9 is a resistor, 10 is a capacitor for starting light emission that can be charged instantly, 11 is a capacitor for flash light emission, 12 is a resistor, 13 is a high-voltage zener for setting the charging voltage of the capacitor 10 for starting light emission. Diode, 1
4 to 16 are resistors, 17 and 18 are transistors, 19 are capacitors that constitute a time circuit together with the resistor 15, and 20
Reference numeral 21 designates a known trigger circuit, and 21 is a known trigger circuit.

Next, the operation will be described using FIG. When the power switch 2 is turned on, the DC/DC converter 3 operates, and a rectified current is generated on the output side of the diode 4.

Further, when the power switch 2 is turned on, a current flows through the resistor 14 to the base of the transistor 17, and the transistor 17 is turned on, so that the thyristor 8 is turned off.

Therefore, first, charging of the light emission starting capacitor IO starts via the diode 7. When the charging voltage of the light emission starting capacitor 10 reaches a certain level or more,
The Zener diode 13 is turned on (conducted) via the resistor 12, and charging of the capacitor 19 is started.

Furthermore, when the charging voltage of the light emission starting capacitor 10 increases, the charging voltage of the capacitor 19 increases, current flows to the base of the transistor 18, and the transistor 18 is turned on. When the transistor 18 is turned on in this way, the current that has passed through the resistor 14 flows into the transistor 18, so the transistor 17 is turned off, and accordingly, the current flows through the resistor 9 to the gate of the thyristor 8. Therefore, the thyristor 8 is turned on. Therefore, this time the thyristor 8. Charging of the flashlight capacitor 11 is started via the diode 5 (see FIG. 2).

During the charging of the flashlight emission capacitor 11, the light emission starting capacitor 10 is not being charged, so the charging voltage of the light emission starting capacitor 10 is gradually discharged.
As a result, when this charging voltage falls below a value that can turn on the Zener diode 13, the transistor 1
8 is turned off, transistor 17 is turned on, and the thyristor 8 is turned off. As a result, charging of the light emission starting capacitor 10 is started again. Thereafter, such operations are repeated. Note that the charging and discharging states of the light emission starting capacitor 10 and the flash light emission capacitor 11 during this repetitive operation are already known and are therefore directly shown in FIG.

Thereafter, when the charging voltage of the flashlight emission capacitor 11 exceeds a certain value, the voltage of the flashlight activation capacitor 10 increases, and this causes the resistance 12. Zener diode 13.
Capacitor 19. The transistor 18 is always on through the resistor 15, and the transistor 17 is always off, and a constant current always flows between the gate and cathode of the thyristor 8 through the resistor 9, so the thyristor 8 is always on. Become. Therefore, from now on, the light emission starting capacitor 1
0 and the flashlight emission capacitor 11 are charged in parallel.

Next, we will explain the operation when a synchronization signal is sent from the camera side.

When a synchronization signal is input from the camera side, a trigger signal is generated in the trigger circuit 21, and the Xe tube 20 emits a flash of light by the charging energy supplied from the light emission starting capacitor 10 and the flash light emission capacitor 11. As a result, the voltage of not only the flash light emission capacitor 11 but also the light emission starting capacitor 10 decreases to the light emission end voltage. In such a case, conventionally, the transistor 18 and the thyristor 8
Since both are turned off, the current flowing through the diode 4 flows through the diode 7 to the light emission starting capacitor 10 and attempts to charge the light emission starting capacitor 10, but at this time, Xe ions are not present in the X e vl 9. As a result, there is a risk that the charging energy of the light emission starting capacitor 10, which is completely charged in an instant, flows to the Xe tube 19, thereby causing a sustained discharge in the Xe tube 19.

In view of this, in this embodiment, as shown in FIG. 2, by detecting that the charging voltage of the light emission starting capacitor 10 has reached a certain voltage or less, Xe ions are The transistor 18 is held in the on state by a time-limiting circuit consisting of the capacitor 19 and the resistor 15 until the thyristor 8 is turned on, and during this period, the flash light emission capacitor 11 is charged in parallel with the light emission starting capacitor 10. I'm trying to do it like this.

In other words, normally the thyristor 8 would be turned off and only the charging of the flashlight starting capacitor 11 would start, but here, the charging of the flashlight starting capacitor 1 would start immediately.
1 is also forcibly charged, and charging of the flashlight capacitor 11 is prohibited after a predetermined period of time has elapsed. This prevents the charging voltages of the light emitting capacitor 11 and the light emitting starting capacitor 1O from rising rapidly, and thus it is possible to prevent sustained discharge of the Xe tube 19.

Furthermore, during this time, since the light emission starting capacitor 10 and the flash light emission capacitor 11 are charged in parallel, there is an effect of hastening the light emission preparation for the next flash photography.

(Correspondence between the invention and the embodiments) In the embodiment shown in FIG.
is the first capacitor of the present invention, the flashlight capacitor 11 is the second capacitor, the resistor 12 and the Zener diode 13 are the detection means, and the thyristor 8. transistor 1
6.17 is the charge control means, and resistor 15. Capacitor 19
correspond to charging command means, respectively.

(Effects of the Invention) As explained above, according to the present invention, a predetermined period of time after a charging voltage drop is detected by the detection means.

A charging command means is provided to forcibly remove the prohibition of charging the second capacitor by the charging control means, and by detecting a drop in the charging voltage of the first capacitor due to flash emission, until a predetermined period has elapsed. Since the first and second capacitors are charged in parallel and the first capacitor is not charged instantaneously during this period, sustained discharge of the flash discharge tube can be prevented. Moreover, it becomes possible to quickly prepare for the next flashlight emission.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, and FIG. 2 is a time chart thereof. 1...Battery, 2...Power switch, 4
~7 diodes, 8...thyristors, 10...
... Capacitor for light emission starting, 11 ... Capacitor for flash light emission, 12 ... Resistor, 13. Old.
・Zener diode, 15... Resistor, 16.
...Capacitor, 17.18 Old...Transistor, 20...Xe tube, 21...Trigger circuit.

Claims (1)

[Claims] (1) A first capacitor with a small capacity for starting light emission, a second capacitor with a large capacity for flashlight emission, and a flashlight discharge tube that emits a flashlight by the charging energy of the first and second capacitors; The first step accompanying the flash emission of the flash discharge tube
a detection means for detecting a drop in the charging voltage of the capacitor; and a detection means that prohibits charging of the second capacitor by detection by the detection means, and when the charging voltage of the first capacitor reaches a light emission starting voltage, the charging voltage of the second capacitor is increased. In the strobe device, the strobe device includes a charging control means for starting charging of
A strobe device comprising: charge command means for forcibly canceling prohibition of charging of the second capacitor by the charge control means.