JPH0715550B2 - Flash device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a flash device including a small-capacity light emission starting capacitor and a large-capacity flash light-emitting capacitor.

(Background of the Invention) Conventionally, in addition to a normal flash-light emitting capacitor, a flash-starting capacitor to be charged in advance is provided, and the flash-light emitting capacitor can be instantly charged even before the charge is not completed. There is proposed a strobe device capable of stable shooting, which corresponds to a quick-shooting property, by using the charged electric charge of a capacitor for activating light emission for activating light emission.

In such a device that starts charging of the flash emission capacitor after charging the emission startup capacitor to the emission startup voltage, the voltage of the emission startup capacitor during flash emission is also the xenon tube (hereinafter referred to as Xe tube). ), The voltage drops to the light emission end voltage, so that the light emission starting capacitor is immediately charged. At this time, the voltage across the Xe tube is the light emission end voltage, but since Xe ions remain, the charging energy to the capacitor for light emission starts to flow through the Xe tube and there is a risk of causing a continuous discharge. It was

(Object of the Invention) A main object of the present invention is to provide a flash device capable of preventing continuous discharge after flash light emission caused by charging only a small-capacity first capacitor for starting light emission. is there.

Another object of the present invention is to prevent continuous discharge after flash light emission due to charging of only the small-capacity first capacitor for light emission start, and to prevent the next flash light from both the light emission start capacitor and the flash light emission capacitor. An object of the present invention is to provide a flash device capable of starting preparations for light emission at the same time.

(Characteristics of the Invention) In order to achieve the above main object, the present invention according to claim 1 of the present application (hereinafter referred to as the first invention) is for light emission start-up connected in parallel to a flash tube. A small-capacity first capacitor and a flash-light-emitting large-capacity second capacitor, a power supply circuit for charging the first and second capacitors, and a charging voltage for the first capacitor. When the charging voltage of the first capacitor is detected and the predetermined voltage is equal to or higher than a predetermined voltage, a charging circuit that forms a charging path for the second capacitor; In a flash device including a trigger circuit for causing the flash tube to emit light by charging energy of a second capacitor, when the flash light is emitted, charging of the first capacitor is prohibited for a predetermined period of time or before the first capacitor. It is characterized in that a prohibition circuit for prohibiting the connection with the flash tube for a predetermined period is provided.

In order to achieve the above-mentioned other object, the present invention described in claim 2 of the present application (hereinafter referred to as the invention of claim 2) is a small-capacity first device for light emission starting, which is connected in parallel to a flash tube. One capacitor and a large-capacity second capacitor for flash light emission, a power supply circuit for charging the first and second capacitors, and a charging voltage of the first capacitor is detected, A charging circuit that forms a charging path for the second capacitor when the charging voltage of the first capacitor is equal to or higher than a predetermined voltage, and the flash tube is triggered by a light emission activation signal to activate the flash tube of the first and second capacitors. In a flash device including a trigger circuit for causing the flash tube to emit light by charging energy, the flash device emits the second light for a predetermined period during flash emission.
Is provided with a charge control circuit for charging the capacitor.

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

FIG. 1 is a circuit diagram showing an embodiment of the first aspect of the invention.
Is a battery as a power source, 2 is a power switch, 3 is a known DC / DC converter for boosting the battery voltage, 4 to 7 are diodes, 8 is a thyristor, 9 is a resistor, and 10 is a light-emission starter that can be charged instantly Capacitor, 11 is a flash light emitting capacitor, 12 is a resistor, 13 is a high voltage Zener diode for setting the charging voltage of the light emission starting capacitor 10, 14 to 16 are resistors,
17, 18 are transistors, 19 is the light emission starting capacitor 1
0 and Xe tube that emits flash light by charging energy from the flash light emitting capacitor 11, 20 is a known trigger circuit, 21 and 22 are diodes, and 23 is a synchro signal from the camera side, so that the transistor 18 is kept for a predetermined time. That is, for example, a one-shot circuit that generates a pulse signal (sustained discharge prevention signal) that is kept in the ON state for a period until the Xe ion disappears in the Xe tube 19 after the Xe tube 19 flashes, 24 is a thyristor, 25 Is a resistor and 26 is a transistor.

Next, the operation will be described with reference to FIG. When the power switch 2 is turned on, the DC / DC converter 3 operates and a rectified current is generated at 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. At this time, since the transistor 26 is off, the thyristor 24 is on. Therefore, first, charging of the light emission starting capacitor 10 is started via the diode 7 and the thyristor 24. When the charging voltage of the light emission starting capacitor 10 becomes a certain value or more, the Zener diode 13 is turned on (conducting state) via the resistor 12, a current flows through the base of the transistor 18, and the transistor 18 is turned on. When the transistor 18 is turned on, the current passing through the resistor 14 flows into the transistor 18, so that the transistor 17 is turned off, and accordingly, the current flows through the gate of the thyristor 8 through the resistor 9, The thyristor 8 is turned on. Therefore, this time, charging of the flash light emitting capacitor 11 is started via the thyristor 8 and the diode 5 (see FIG. 2).

Since the light emission starting capacitor 10 is not being charged while the flash light emitting capacitor 11 is being charged, the charge voltage of the light emitting starting capacitor 10 is gradually discharged, and the result is that this charge voltage is the zener. When the diode 13 is turned below a value that can be turned on, the transistor 18 is turned off, the transistor 17 is turned on, and the thyristor 8 is turned off. As a result, the charging of the light emission starting capacitor 10 is started again. After that, such an operation is repeated. Note that the capacitor for starting the light emission during this repeated operation
Since the charging and discharging states of 10 and the flash light emitting capacitor 11 are already known, they are shown linearly in FIG.

After that, when the charging voltage of the flash light emitting capacitor 11 becomes higher than a certain value, the voltage of the light emission starting capacitor 10 rises, whereby the transistor 18 is always turned on through the resistor 12 and the Zener diode 13, and the transistor 17 is always turned on. It turns off, and a resistor 9 is placed between the gate and cathode of the thyristor 8.
Since a constant current or more always flows through the thyristor 8, the thyristor 8 is always turned on. Therefore, thereafter, the light emission starting capacitor 10 and the flash light emitting capacitor 11 are charged in parallel.

Next, the operation when the synchronizing signal is sent from the camera side will be described.

When the synchronizing signal is input via the diode 22, a trigger signal is generated in the trigger circuit 20, and the Xe tube 19 flashes light by the charging energy supplied from the light emission starting capacitor 10 and the flash light emitting capacitor 11. As a result, not only the flash light emitting capacitor 11 but also the light emission starting capacitor 10
Also drops to the light emission end voltage. In such a case, in the conventional case, since the transistor 18 and the thyristor 8 are both turned off, the current flowing through the diode 4 flows to the light emission starting capacitor 10 through the diode 7 and charges the light emission starting capacitor 10. When Xe tube 19 Xe
Since the ions remain, the charging energy of the light emission starting capacitor 10 that will be instantly charged will flow to the Xe tube 19,
As a result, there is a risk that the Xe tube 19 causes a continuous discharge.

In view of this point, in the present embodiment, as shown in FIG. 2, the one-shot circuit 23 sends a continuous discharge prevention signal from the one-shot circuit 23 for a predetermined period in accordance with the input of the synchronizing signal, that is, a period from the start of flash light emission to the disappearance of Xe ions. Is output to the base of the transistor 26, and during this time, the thyristor 24 is forcibly turned off so that the charging path to the light emission starting capacitor 10 is cut off. As a result, the potential of the light emission starting capacitor 10 does not rise, so that the continuous discharge of the Xe tube 19 can be prevented.

After that, when the continuous discharge prevention signal output from the one-shot circuit 23 is stopped, the thyristor 24 returns to the ON state, so that the normal charging operation, that is, the charging of the light emission starting capacitor 10 is started, and the light emission is started. When the potential of the starting capacitor 10 reaches the light emission starting voltage, charging of the flash light emitting capacitor 11 is started.

FIG. 3 shows another embodiment of the first aspect of the invention. The parts different from the embodiment of FIG. 1 are the same as those of the switching circuit shown in the embodiment of FIG. The point is that a switching circuit including a transistor 29 is arranged between the light emission starting capacitor 10 and the Xe tube 19.

With such a configuration, when the continuous discharge inhibit signal is input through the diode 21 and the resistor 16 in synchronization with the synchro signal, the transistor 29 is turned on and the thyristor 27 is turned off during this period. Therefore, while the thyristor 27 is off, charging of the light emission starting capacitor 10 is immediately started, but the charging energy is not transmitted to the Xe tube 19 and the continuous discharge is prevented as in the embodiment of FIG. be able to. Also, during this period, as described above,
Since charging to 10 has started, preparation for the next shooting will be completed soon.

FIG. 4 shows an embodiment of the invention set forth in paragraph 2. The parts different from the practical examples of FIGS. 1 and 3 are the diode 21 and the resistor 1
The continuous discharge prevention signal input via 6 is applied to the transistor 18
The point is that the output is directly output to the base of.

With such a structure, when the continuous discharge prohibition signal is input through the diode 21 and the resistor 16 in synchronization with the synchro signal, both the transistor 18 and the thyristor 8 are turned on during this period, and the flash light is emitted as shown in FIG. The light emitting capacitor 11 is charged in parallel with the light emitting starting capacitor 10. Therefore, the charging of the light emission starting capacitor 10 is not instantaneously completed, and the Xe tube 19 does not cause a continuous discharge due to the charging energy. Also in this case, as in the case of the embodiment shown in FIG. 3, the preparation for the next photographing is completed early.

(Correspondence between Invention and Embodiment) In the embodiment shown in FIG. 1, the flash light emitting capacitor 11 is the second capacitor of the present invention, and the light emission starting capacitor 10 is
Is the first capacitor, the DC / DC converter 3 for boosting the battery voltage is the power supply circuit, the thyristor 8, the resistors 9,12,15, the Zener diode 13, the transistors 17,18 are the charging circuit,
The one-shot circuit 23, the thyristor 24, the resistor 25, and the transistor 26 correspond to the inhibition circuit, respectively. In the embodiment shown in FIG. 3, the one-shot circuit 23, the thyristor 27,
The resistor 28 and the transistor 29 correspond to the inhibition circuit, and in the embodiment shown in FIG. 4, the one-shot circuit 23 corresponds to the charge control circuit.

(Modification) In the illustrated embodiment, the rising edge of the continuous discharge prevention signal is synchronized with the trigger signal (synchro signal), but the present invention is not limited to this, and even after the peak of the flash light emission waveform is exceeded. good. Also, depending on the type of discharge tube, its light emission time,
Although the ion annihilation time varies, it is easy to set the sustained discharge prevention signal generation period according to the type of these discharge tubes.

(Effect of the Invention) As described above, according to the first invention of the present application, during flash light emission, charging of the first capacitor for light emission activation is prohibited for a predetermined period, or the connection between the first capacitor and the flash tube is prevented. Since it is prohibited for a predetermined period, it is possible to prevent the continuous discharge after the flash light emission due to the charging of only the small-capacity first capacitor.

Further, according to the second aspect of the present invention, when the flash light is emitted, the second capacitor for flash light emission is charged for a predetermined period, so that after the flash light emission, the first and second capacitors are kept for a predetermined period. Since it is charged so that the charge level of the first small-capacity capacitor does not rise sharply,
It prevents continuous discharge after flash light emission due to charging only the small first capacitor, and
The next flash preparation can be started at the same time for the capacitors of the above.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a timing chart thereof, FIG. 3 is a circuit diagram showing another embodiment of the present invention, and FIG. 4 is another embodiment of the present invention. Circuit diagram,
FIG. 5 is the timing chart. 1 ... Battery, 2 ... Power switch, 4-7 diodes,
8 ... Thyristor, 10 ... Capacitor for starting light emission, 11 ...
… Flash light emitting capacitor, 17,18 …… Transistor, 19
Xe tube, 20 trigger circuit, 23 one-shot circuit, 24 thyristor, 25 resistor, 26 transistor, 27 thyristor, 28 resistor, 29 transistor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-49-44740 (JP, A) JP-A-53-12176 (JP, A) JP-A-57-202696 (JP, A)

Claims (2)

[Claims] 1. A small-capacity first capacitor for starting light emission and a large-capacity second capacitor for flashing, both of which are connected in parallel to a flash tube, and to the first and second capacitors. A power supply circuit for charging and a charging circuit that detects a charging voltage of the first capacitor and forms a charging path for the second capacitor when the charging voltage of the first capacitor is equal to or higher than a predetermined voltage. And a trigger circuit for triggering the flash tube by a light emission activation signal to cause the flash tube to emit light by the charging energy of the first and second capacitors, the flash device including: A flash device, comprising: a prohibition circuit that prohibits charging of the capacitor for a predetermined period or prohibits connection of the first capacitor and the flash tube for a predetermined period. 2. A small-capacity first capacitor for starting light emission and a large-capacity second capacitor for flashing light emission, which are connected in parallel to the flash tube, and to the first and second capacitors. A power supply circuit for charging and a charging circuit that detects a charging voltage of the first capacitor and forms a charging path for the second capacitor when the charging voltage of the first capacitor is equal to or higher than a predetermined voltage. And a trigger circuit for triggering the flash tube by a light emission activation signal to cause the flash tube to emit light by the charging energy of the first and second capacitors, in flash light emission, the flash circuit is provided for a predetermined period of time. A flash device comprising a charge control circuit for charging the second capacitor.