JPS6392935A - Stroboscopic device - Google Patents

Abstract

PURPOSE:To suppress the continuous discharge of a flash discharging tube within a short period by providing the titled device with a charging command means of forcedly releasing the inhibition of charge to a capacitor based upon charge control at the time of detection based upon a continuous discharge detecting means to detect the continuous discharge of a flash discharge tube. CONSTITUTION:Since current flows through a resistor 29 at the time of continuous discharge, the cathode voltage of a Xe tube 18 reaches about 10-200V for about 1ms. Thereby, a resistor 20 is arranged between the cathode of the Xe tube 18 and the base of a transistor (TR) 17. When continuous discharge is started, current flows into the base of the TR 17 through the resistor 20, the TR 17 is turned on, the thyristor 8 is turned on, and current flowing from a DC/DC converter 3 flows into also a light emitting capacitor 11. Namely, charge to the capacitor 11 is executed simultaneously with charge to the capacitor 10. Thereby, the charging voltage to the capacitor 10 is not suddenly boosted and the coninuous discharge can be ended within a short period.

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 a device that starts charging the flash light emission capacitor after charging the light emission starting capacitor to the light emission starting voltage in this way, 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 at both ends of the Xe tube is the emission final voltage, but since Xe ions remain, the charging energy to the capacitor for starting the emission will flow through the Xe tube, and there is a risk of causing a sustained discharge. there were.

(Object of the Invention) An object of the present invention is to provide a strobe device that can suppress sustained discharge of a flash discharge tube in a short period of time.

(Features of the Invention) In order to achieve the above object, the present invention provides a continuous flash discharge tube caused by the charging control means immediately starting charging the first capacitor in conjunction with flash light emission. A sustained discharge detection means for detecting discharge, and a charging command means for forcibly releasing the inhibition of charging to the second capacitor by the charge control means based on the detection by the sustained discharge detection means,
The first and second capacitors are charged in parallel by detecting sustained discharge of the flash discharge tube, and the first capacitor is not charged instantaneously during this period. .

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

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.
is a battery which is a power source, 2 is a power switch, 3 is a known DC/DC converter for boosting battery voltage, 4 to 7
8 is a diode, 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, and 13 is a high voltage for setting the charging voltage of the capacitor 10 for starting light emission. Zener diode, 14.15 is resistor, 16.17 is transistor, 18
19 is a known trigger circuit; 20 detects sustained discharge;
21 is a resistor for turning on the transistor 17, 21 is a thyristor for controlling the Xe tube 18, 22 is a coil 23.
a commutation capacitor that constitutes a light emission stop circuit that stops the light emission of the X e % i' 18 together with the switch 24;
25 is a resistor for starting the thyristor 21 together with the capacitor 26, 27 is a resistor that together with the capacitor 28 constitutes a protection circuit for the thyristor 21, and 29.30 is a resistor for charging the capacitor 22.

Next, the operation will be explained. 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, the transistor 16 is connected to the transistor 16 via the resistor 14.
A current flows to the base of the transistor 16, which turns on the thyristor 8, so that the thyristor 8 is turned off. Therefore, first, charging of the light emission starting capacitor 10 via the diode 7 is started. When the charging voltage of the light emission starting capacitor 10 exceeds a certain value, the Zener diode 13 turns on (conducts) via the resistor 12.
Current flows through the resistor 15 to the base of the transistor 17, turning on the transistor 17. When the transistor 17 is turned on in this way, the current passing through the resistor 14 flows into the transistor 17, so the transistor 16
is turned off, and along with this, a resistor 9 is connected to the gate of thyristor 8.
Since current starts to flow through the thyristor 8, the thyristor 8 is turned on. Therefore, this time the thyristor 8. diode 5
Charging of the flashlight capacitor 11 is started via the flashlight emitting capacitor 11. 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, and as a result, this charging voltage is applied to the Zener diode. When the value falls below a value that can turn on the transistor 13, the transistor 17 is turned off, the transistor 16 is turned on, and the thyristor 8 is turned off. As a result, charging of the light emission starting capacitor lO is started again. Thereafter, such operations are repeated in a known manner.

After that, when the charging voltage of the flashlight emission capacitor 11 becomes equal to or higher than a certain voltage, the voltage of the light emission starting capacitor 10 increases, and as a result, the resistance 12° Zener diode 13
Transistor 17 is always on through transistor 17 and transistor 16 is always off, and since a current higher than the current always flows between the gate and cathode of thyristor 8 through resistor 9, thyristor 8 is always on. Therefore, thereafter, charging of the light emission starting capacitor 10 and the flash light emission capacitor 11 continues simultaneously.

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

When a synchronization signal is input to the trigger circuit 19 from the camera side, a trigger signal is generated in the trigger circuit 19, and the charging energy of the capacitor 10 for starting one light emission and the capacitor 11 for flash light emission is transferred to the Xe tube 18, the capacitors 22, 26, and It passes through the resistor 25 and turns on the thyristor 21. As a result, the Xe tube 18 emits flash light due to the charging energy.

When the light emission end voltage is reached, the flash light emission at the X e vl 8 is stopped, and at the same time, the thyristor 21 is turned off because the current becomes less than the holding current.

With the charging method described above, when the flash fires, Cyrisk 21
When the light emission starting capacitor 10 is on, the charging voltage of the light emission starting capacitor 10 drops to the light emission end voltage, but at this time, since the transistor 17 is off, charging of the light emission starting capacitor 10 has already started. That is, when the flash light is emitted, the current from the capacitor 10911 and the DC/DC converter 3 is involved in the light emission. However, the holding current of the thyristor 21 is often larger than the current value from the DC70C converter 3, and the thyristor 21 is turned off when the light emission end voltage is reached. At this time, since Xe ions still remain in the Xe tube 18, the current from the DC/DC converter 3 flows through the Xe tube 18 and the resistor 29. This state is a sustained discharge, and the discharge time is several meters to several hundred
m5 and various others.

The sustained discharge time will be described below. Resistor 2 during continuous discharge
Since current flows through the Xe tube 9, the cathode voltage of the Xe tube 18 reaches several tens to 200 V in about 1 ms. Therefore, the resistor 20 is connected to the cathode of the Xe tube 18 and the transistor 17.
It is placed between the bases. As a result, when sustained discharge begins, current flows through the resistor 20 to the base of the transistor 17, which turns on the transistor 17. Accordingly, the thyristor 8 turns on, and the current from the DC70C converter 3 flows into the light emitting capacitor. 11, that is, charging of the light emission capacitor 11 is performed in parallel with charging of the light emission starting capacitor 10. Therefore, the charging voltage of the light emission starting capacitor 10 does not rise suddenly, and therefore, the sustained discharge ends in a short time.

FIG. 2 shows a second embodiment of the present invention, in which a resistor 31 . It has a configuration in which a capacitor 32 and backflow prevention diodes 33 and 34 are added.

In this way, resistance 31. By providing a time-fixed circuit consisting of a capacitor 32, the current flowing through the resistor 20 during sustained discharge charges the capacitor, and as a result, it is possible to guarantee that the transistor 17 is in an on state for a predetermined period of time. Although the sustained discharge time is slightly longer than in the example, the probability that subsequent sustained discharges can be more reliably prevented is increased.

FIG. 3 shows a third embodiment of the present invention, in which a backflow prevention diode 35 is added between the cathode of the Xe tube 18 shown in FIG. 2 and the commutation capacitor 22. .

The difference from the embodiment shown in FIG. 2 is in dimming. That is, in the embodiment shown in FIG. 2, during dimming, as shown in FIG. 4(a), the Xe tube 18 is
The cathode voltage of LoomS is about 100V. Due to this influence, the transistor 17 continues to be turned on, and even though the charging of the light emitting capacitor 11 progresses, only one light emitting starting capacitor 10 is charged.
Since charging is not performed, there is a possibility that a flash will not be emitted during quick shooting because the charging voltage of the light emission starting capacitor 10 is lower than the light emission starting voltage. To prevent this,
The value of the resistor 20 may be increased, but as the value of the resistor 20 increases, the time delay in detecting sustained discharge increases. Further, when the power voltage is only about 100 to 150 V during flash emission, it is difficult to control the flash light emission or dimming because it cannot be distinguished by the resistor 20 alone.

However, by adding the diode 35 as in the embodiment shown in FIG. 3, although the cathode voltage rises during dimming and when the commutation capacitor 22 is being charged, the period of time is short; When the capacitor 22 is discharged, the cathode of the Xe tube 18 does not pass through due to the action of the diode 35, so the voltage becomes as shown in FIG. It can be resolved. Also, by adding the diode 35,
The value of the resistor 20 can be made small, and as a result, the sustained discharge detection time can be shortened. In addition, when dimming.

Although charging of the light emission starting capacitor 10 is not performed, the time is short and charging of the light emission capacitor 11 progresses during that time, so there is no actual damage.

FIG. 5 shows a fourth embodiment of the present invention (a modification of the embodiment shown in FIG. Capacitor 36 for transmitting only the component to transistor 17
It has a configuration with the addition of.

By adopting such a configuration, it is possible to obtain the same effects as the embodiment shown in FIG. 3, except for the disadvantage that a response delay occurs during both flash emission and dimming.

(Correspondence between the invention and the embodiments) In the embodiment shown in FIG.
is the second capacitor of the present invention, the light emission starting capacitor 10 is the first capacitor, and the thyristor 8. The transistors 16 and 17 serve as charge control means, the resistor 20 serves as sustained discharge detection means, and the thyristor 8.17 serves as the charge control means. Transistors 16, 17 respectively correspond to charging command means (that is, they are also used), and in the embodiment shown in FIG. 2.3.5, diodes 34. capacitor 32, resistor 3
1 corresponds to the charging command means.

(Effects of the Invention) As explained above, according to the present invention, the continuation of the flash discharge tube caused by the charge control means immediately starting charging the $1 capacitor with the flash light emission. A sustained discharge detection means for detecting discharge, and a charge command means for forcibly releasing the inhibition of charging to the second capacitor by the charge control means based on the detection by the sustained discharge detection means, thereby preventing the sustained discharge of the flash discharge tube. , the first and second capacitors are charged in parallel, and during this time the first
If we prevent the capacitor from charging instantly,
The sustained discharge of a flash discharge tube can be suppressed for a short time.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a first embodiment of the invention, Fig. 2 is a circuit diagram showing a second embodiment of the invention, and Fig. 3 is a circuit diagram showing a third embodiment of the invention. , FIG. 4 is a diagram for explaining the cathode voltage of the Xe tube during dimming in the embodiment shown in FIGS. 2.3, and FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention. l...Battery, 2...Power switch, 4
~7 diodes, 8...thyristors, 10...
... Capacitor for starting light emission, 11 ... Capacitor for flash light emission, 16.17 ... ... Transistor, 18 ... Xe tube, 19 ... Trigger Circuit, 20... Resistor, 21... Thyristor, 22... Commutation capacitor, 31...
...Resistance, 32...Capacitor, 35...
··diode. 36...Capacitor.

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; Charging of the second capacitor is prohibited until the charging voltage of the first capacitor, which is immediately charged by the flash light emission of the flash discharge tube, reaches a light emission starting voltage, and after reaching the light emission starting voltage, charging of the second capacitor is prohibited. In the strobe device, a continuous discharge of the flash discharge tube occurs due to the charge control means starting charging the first capacitor immediately upon flash emission. What is claimed is: 1. A strobe device comprising: a sustained discharge detecting means for detecting a continuous discharge; and a charging command means for forcibly releasing the inhibition of charging of the second capacitor by the charging control means upon detection by the sustained discharge detecting means.