JPH08304888A - Stroboscopic circuit - Google Patents

Abstract

PURPOSE: To select the propriety of strobe light emission even when a main capacitor is charged. CONSTITUTION: When a stroboscope charging switch 7a is turned on, a booster part 20 is actuated to charge the main capacitor 31 and a trigger capacitor 41. In the case the strobe light emission is not performed when the main capacitor 31 is charged and the strobe light emission is possible, a strobe light emission inhibiting button is depressed, and a shutter button is depressed in a state where a strobe light emission change-over switch 12a is turned off. When a shutter is actuated and totally opened, a trigger switch 43 is turned on, but the switch 12a is turned off, so that the trigger capacitor 41 is not discharged and the trigger voltage is not generated in the secondary coil 42b of a trigger transformer 42. Since the trigger voltage is not impressed on a trigger electrode 32a, the charge of the main capacitor 31 is not discharged in a stroboscope discharge tube 32 and the strobe light emission is not performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strobe circuit.

[0002]

2. Description of the Related Art Some camera and film units with lenses have a built-in strobe, which is convenient for photographing in a dark place. When performing flash photography, it is necessary to charge the main capacitor in advance to a specified charging voltage and apply a trigger voltage of several KV to the flash discharge tube. For this reason, the strobe charging switch is usually turned on prior to stroboscopic photography.

In the strobe circuit, when the strobe charging switch is turned on, the low voltage of the power source is boosted by, for example, 300
The voltage is boosted to a high voltage of V and the main capacitor is charged with this high voltage. Then, after the main capacitor reaches the specified charging voltage, for example, when the shutter button of the lens-fitted film unit is pressed to operate the shutter, the trigger voltage is applied to the strobe discharge tube in synchronization with the operation of the shutter, The electric charge charged in the main condenser is discharged in the strobe discharge tube, and the strobe discharge tube emits light.

In the strobe circuit, the main capacitor is charged only while the strobe charging switch provided in the strobe circuit is turned on. When the strobe charging switch is turned on once, a predetermined time, for example, 15 minutes. There are things such as recharging repeated until. Also, once the strobe charge switch is turned on once, even if the strobe charge switch is turned off after that, the main capacitor is charged to the specified charge voltage and then the charging is stopped.
A device in which a booster circuit is controlled by a transistor or the like has been proposed (for example, Japanese Patent Application No.
268983).

[0005]

By the way, in a state where the main capacitor is charged, regardless of the intention of the photographer,
Flash photography is done. For this reason, where flash photography is prohibited, such as in museums and temples, when the main capacitor is charged,
There was a problem that I could not shoot. Also, in the strobe circuit that automatically recharges as described above, when shooting in a place where strobe shooting is prohibited, make sure that the main capacitor is not charged before entering this place, and the main capacitor is When the battery is being charged, it is necessary to carry out stroboscopic photography so that the stroboscopic light is not emitted, which is inconvenient because unnecessary photography is required. Furthermore, Japanese Patent Application No. 5
In the strobe circuit of No. 268983, even if the strobe charge switch is not turned on, noise may occur when the trigger voltage is generated, and the main capacitor may be charged. Therefore, even if the flash is not intended for the next shooting, the flash may be emitted.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a strobe circuit capable of prohibiting strobe light emission even when the main capacitor is charged.

[0007]

In order to achieve the above object, in the invention according to claim 1, the trigger circuit for applying the trigger voltage to the strobe discharge tube is such that the trigger voltage is applied to the strobe discharge tube. A changeover switch that is movable between an allowable light emission position and a light emission prohibition position that blocks the application of the trigger voltage is provided, and this changeover switch is switched between the light emission position and the light emission prohibition position in response to the operation of the external operation member. Thus, it is possible to select whether or not the strobe discharge tube needs to emit light.

According to another aspect of the present invention, the trigger circuit includes a trigger capacitor that is charged together with the charging of the main capacitor, and a trigger transformer that generates the trigger voltage by the discharge current of the trigger capacitor. The discharge of the trigger capacitor is prohibited by switching to the light emission prohibiting position that blocks the application of.

According to the third aspect of the present invention, the neon tube for indicating the completion of charging of the main capacitor is prohibited from being turned on by switching the changeover switch to the light emission prohibiting position.

According to another aspect of the present invention, the trigger circuit includes a trigger capacitor that is charged together with the charging of the main capacitor, and a trigger transformer that generates the trigger voltage by the discharge current of the trigger capacitor. By switching to the position, the resistor for discharging the trigger capacitor discharges the discharge current so that the discharge current does not flow through the trigger transformer.

According to another aspect of the present invention, the changeover switch is a self-reset type switch, and the changeover switch can be switched to the light emission inhibition position only when the external operation member is pressed.

[0012]

[Function] If the main capacitor is charged but the user does not want to use the flash, the changeover switch is operated. By this operation, the changeover switch is changed over to the light emission prohibition position. When the selector switch is in the flash off position, the trigger voltage is not applied to the strobe discharge tube because the discharge current does not flow to the trigger transformer even if the trigger switch is closed at the timing of flashing the strobe, so the main capacitor does not discharge. Strobe discharge tube does not fire.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a film unit with a built-in strobe according to the present invention (hereinafter referred to as a film unit with a strobe). The film unit with a strobe has a film built in a unit body 1 having a simple photographing mechanism, and the unit body 1 is covered with an outer case 2. The outer case 2 is provided with an opening through which the taking lens 3, the finder 4, the winding knob 5 and the like are exposed, and the photographing operation can be performed with the unit body 1 kept in the outer case 2.

A photographing lens 3 is arranged at the center of the front surface of the unit body 1. A finder 4 is provided above the taking lens 3, a strobe light emitting section 6 is arranged on the right side of the finder 4, and a strobe charging switch 7a (see FIG. 1) is turned on and off on the right side of the taking lens 3. Button 7 is provided. When flash photography is performed, the operation button 7 is pressed before photography to charge the main capacitor. A shutter button 9, a display window 10 for confirming the number of remaining films, and a display window 11 for confirming completion of strobe charging are provided on the upper surface of the strobe-equipped film unit.

As shown in FIG. 3, a winding knob 5, an eyepiece portion 4a of the finder 4 and the like are arranged on the rear surface of the film unit with a strobe, and a strobe light emission changeover switch 12a (FIG. 1) is provided at the upper left end. Reference) ON-O
A flash emission prohibition button 12 for FF is provided. When photographing is performed without strobe light emission, the shutter button 9 is pressed while the strobe light emission prohibition button 12 is pressed to perform photographing. When the flash emission prohibition button 12 is not pressed, the flash emission is enabled.

Since the strobe light emission prohibition button 12 is not frequently used, it may be provided at the upper corner or the back side of the strobe-equipped film unit, but the strobe-equipped film unit can be held by the left and right hands. It is better to install it in a position where you can continue pushing without losing your posture. That is, it is preferable that the strobe light emission prohibition button 12 is provided at a position where the shutter button 9 can be easily pressed while pressing it to take a picture. In the illustrated embodiment, when the film unit with a strobe is held, the strobe emission prohibition button 12 is arranged at a position where the right hand can press the shutter button 9 while pressing the strobe emission prohibition button 12 with the thumb of the left hand, for example. .
Other positions of the strobe prohibiting switch 12 include positions indicated by reference numerals 15a and 15b in FIG. 3 and reference numeral 15 in FIG.
It may be the position shown in c.

FIG. 1 shows a strobe circuit incorporated in a strobe-equipped film unit. The strobe circuit is roughly divided into a booster section 20 and a charging / light emitting section 30. The booster unit 20 includes a battery 20 as a power supply source and an oscillation transistor 2
2, an oscillation transformer 23, a control transistor 24, an oscillation stop transistor 25, a Zener diode 26, a rectifying diode 27, and a strobe charging switch 7a that is turned on only when the operation button 7 is pressed. .

Oscillation transistor 22 and oscillation transformer 23
Is a well-known blocking oscillation circuit, and when the strobe charging switch 7a is turned on, a base current flows into the oscillation transistor 22 and the oscillation transistor 2
2 starts operating. When the oscillation transistor 22 starts operating, it oscillates due to the positive feedback action from the oscillation transformer 23. Also, when the oscillation transistor 22 operates,
The base current of the control transistor 24 flows to start the operation. As a result, the voltage of the battery 20 changes between the emitter and collector of the control transistor 24 and the tertiary coil 23c.
Is applied as a base voltage to the oscillation transistor 22 via. Therefore, once the strobe charging switch 7a is turned on and oscillation starts, the oscillation transistor 22 continues to oscillate after the strobe charging switch 7a is turned off by the positive feedback action of the control transistor 24. .

While the oscillation transistor 22 is oscillating,
Since the primary side current flowing through the primary coil 23a of the oscillation transformer 23 repeatedly increases and decreases, an electromotive force of 350 V and a flyback voltage (counterelectromotive force) are generated in the secondary coil 23b. The secondary side current flowing through the secondary coil 23b by the electromotive force is supplied to the charging / light emitting unit 30. When flyback voltage occurs, rectifying diode 2
Due to the rectifying action of 7, the secondary current does not flow.

When the main capacitor 31 is charged and the voltage between its both terminals reaches the specified charging voltage (for example, 350 V), the Zener diode 26 causes a Zener current (reverse current) to flow and activates the stop transistor 25. Let When the stop transistor 25 operates, the base voltage from the control transistor 24 is not applied to the oscillation transistor 22, so that the operation of the oscillation transistor 22 is stopped, and the control transistor 24 is accordingly stopped.
Is also stopped. That is, the main capacitor 31
When the voltage reaches the specified charging voltage, charging of the main capacitor 31 is stopped. Thus, in this strobe circuit, when the main capacitor 31 is charged, the main capacitor 31 is charged to the specified charging voltage even if the operation button 7 is pressed and immediately released. ing.

The booster 20 uses the control transistor 24, the stop transistor 25, etc. even if the strobe charging switch 7a is turned on and then immediately turned off.
Although the main capacitor 31 is charged to the specified charging voltage, the main capacitor 31 may be controlled to be charged to the specified charging voltage using, for example, a timer. Further, the main capacitor may be charged only when the strobe charge switch is turned on.

The charging / light emitting unit 30 is composed of the main capacitor 3
1, a strobe discharge tube 32, a trigger electrode 32a, a neon tube 33, a trigger circuit 40 and the like. The trigger circuit 40 is composed of a trigger capacitor 41, a trigger transformer 42, a trigger switch 43, and a strobe light emission changeover switch 12a. Main capacitor 3
1, the both terminals are connected to both electrodes of the strobe discharge tube 32, the positive terminal is connected to the negative side of the battery 21 and is grounded (ground), and the negative terminal is secondary through the rectifying diode 27. It is connected to one end of the coil 23b.

The trigger transformer 42 comprises a primary coil 42a and a secondary coil 42b which are inductively coupled to each other.
One end of the primary coil 42a is grounded via the trigger capacitor 42 and the strobe light emission changeover switch 12a, and the other end is grounded via the trigger switch 43. From the one end of the primary coil 42a, the trigger capacitor 41, the strobe light emission changeover switch 12a, A circuit in which the trigger switch 43 and the other end of the primary coil 42a are connected in this order (hereinafter referred to as a primary side trigger circuit) is formed. In addition, one end of the secondary coil 42b is connected to the trigger electrode 32a, and the other end of the secondary coil 42b is connected to the one end of the primary coil 42a together with the trigger switch 43.
Grounded through.

The trigger switch 43 is turned on and off in synchronization with the operation of the shutter, and is turned on when the shutter is operated and fully opened. Strobe emission switch 12a
Is a self-reset type switch that is interlocked with the strobe light emission prohibition button 12, and is turned off (light emission prohibition position) only while the strobe light emission prohibition button 12 is pressed, and is self-restored and turned on (when light is released). Return to the light emitting position).

The current supplied from the booster 20 charges the main capacitor 31 and the trigger capacitor 42 via the strobe light emission changeover switch 12a in the ON state. When the trigger switch 43 is turned on while the strobe light emission changeover switch 12a is turned on, the charged trigger capacitor 41 is discharged because the primary side trigger circuit becomes a closed circuit. As a result, a current flows through the primary coil 42a of the trigger transformer 42, and a high voltage, for example, a trigger voltage of 4 KV is generated in the secondary coil 42b. This trigger voltage is applied to the strobe discharge tube 3 via the trigger electrode 32a arranged in the vicinity of the strobe discharge tube 32.
2 is applied. By applying this trigger voltage, the Xe gas in the strobe discharge tube 32 is ionized and the resistance between both electrodes of the strobe discharge tube 32 is broken, and the main capacitor 3
1 discharges and the strobe discharge tube 32 emits light.

The flash emission changeover switch 12a is OF
When it is F, even if the trigger switch 42 is turned on, the trigger capacitor 42 is not discharged because the primary side trigger circuit does not become a closed circuit. Therefore, since the trigger voltage is not applied to the trigger electrode 32a, the strobe discharge tube 32 does not emit light.

The neon tube 33 is connected to both terminals of the main capacitor 31 via resistors 41a and 33a and a strobe light emission changeover switch 12a. When the main capacitor 31 is charged to the specified charging voltage while the flash light emission changeover switch 12a is ON, the specified charging voltage of the main capacitor 31 is applied to the neon tube 33 to light up. The neon tube 31 is arranged at a position facing the display window 11, and the photographer can confirm the lighting of the neon tube 33 through the display window 11. As a result, the photographer can know that the preparation for strobe emission has been completed. The neon tube 33 is connected to the main capacitor 31 via the flash light emission changeover switch 12a so that when the flash light emission is prohibited, even if the main capacitor 31 is charged up to the specified charging voltage, the neon tube 33 does not light up. It is becoming clear that light emission is prohibited.

The flash emission changeover switch 12a
Is provided on the circuit between the secondary coil 42b of the trigger transformer 42 and the trigger electrode 32a shown by reference numeral 50a in FIG. 1, so that the trigger voltage is not applied to the strobe discharge tube 32 via the trigger electrode 32a. You can disable the flash firing. Further, by providing it on the circuit between the strobe discharge tube 32 and the main capacitor 31 shown by reference numeral 50b, even if a trigger voltage is applied to the strobe discharge tube 32, the main capacitor 31 is prevented from discharging, and strobe light is emitted. Can be banned.
However, when the strobe light emission changeover switch 12a is provided at the positions 50a and 50b, when the trigger switch is turned on, the strobe light emission changeover switch 12a is turned off.
Even if it is FF, the trigger capacitor 41 is discharged, resulting in unnecessary power consumption.

Further, a strobe light emission changeover switch, which is turned on when the strobe light emission is prohibited to the main capacitor 31, is connected in parallel with the strobe discharge tube, and the electric charge of the main capacitor 31 is discharged by the discharge resistor before photographing. Even if it is done, it is possible to prevent the stroboscopic light emission. However, in such a case, in order to discharge the electric charge of the main capacitor 31 in the shortest possible time, a large discharge resistor having a large rated power is required, and a strobe circuit and a strobe-equipped film unit having the strobe circuit built-in are required. This hinders the miniaturization of the camera. Furthermore, when the flash firing switch is turned on,
Since the electric charge charged in the main capacitor 31 is discharged, it is necessary to charge the main capacitor 31 again, which results in wasteful consumption of electric power, and there is a problem in that recharging takes time.

Further, it is possible to dispose the stroboscopic light emission changeover switch 12a on the circuit indicated by reference numeral 50c to prohibit the stroboscopic light emission without discharging the trigger capacitor 41. In this case, however, the stroboscopic light emission is turned off. The neon tube 33 lights up even when prohibited. For this reason, it becomes impossible to determine whether or not strobe light emission is prohibited.

For this reason, the strobe light emission changeover switch 12a is turned off by connecting as shown in FIG.
It is preferable that the neon tube 33 is not turned on during the period, and the trigger capacitor 41 is not discharged even when the trigger switch 43 is turned on. Further, the flash emission changeover switch 12a is, as described above,
Flash emission is prohibited in the self-recovery state (OFF
It is better to use self-recovery type. For example, when a slide switch or a switch that switches ON-OFF each time the switch is pressed is used, if the photographer forgets that the flash firing is prohibited, stroboscopic photography will be performed. Turn on the strobe charge switch 7a as
If it is set, the main condenser 31 is charged, but
This is to prevent the problem that the stroboscopic light is not emitted even when taking a picture.

Next, the operation of the above configuration will be described.
The photographer winds the film by rotating the winding knob 5. Next, when performing flash photography, the operation button 7 on the front surface of the film unit with a flash is pressed.
This pressing may be released immediately. The strobe emission prohibition button 12 is not pressed.

When the operation button 7 is pressed, the strobe charging switch 7a is turned on and the oscillation transistor 22 starts operating. The oscillation transistor 22 oscillates by the positive feedback action from the oscillation transformer 23. On the other hand, the control transistor 24 starts to operate when the oscillation transistor 22 operates, and the oscillation transistor 2
A base voltage is applied to 2. As a result, the operation button 7
The oscillation of the oscillation transistor 22 is continued even if the pressing of is released.

During the oscillation of the oscillating transistor 22, a current flows or does not flow in the primary coil 23a, so that an electromotive force and a flyback voltage are generated in the secondary coil 23b according to the winding ratio with the primary coil 23a. To do. And
By the action of the rectifying diode 27, only the secondary side current due to the electromotive force is supplied to the charging / light emitting unit 30.

The main capacitor 31 is charged by the secondary current supplied to the charging / light emitting unit 30, and the trigger capacitor 41 is charged via the strobe light emission changeover switch 12a in the ON state. When the charging of the main capacitor 31 progresses and the voltage between both terminals of the main capacitor 31 reaches the specified charging voltage, a Zener current flows through the Zener diode 26 and the stopping transistor 2
5 is activated. As a result, the control transistor 24
The voltage from is no longer applied to the base terminal of the oscillation transistor 22, and the operation of the oscillation transistor 22 stops,
Along with this, the operation of the control transistor 24 also stops. When the operation (oscillation) of the oscillation transistor 22 is stopped, a high voltage is not generated in the secondary coil 23b and the charging of the main capacitor 31 is stopped.

When the main capacitor 31 is charged to the specified charging voltage, the neon tube 33 lights up. The photographer confirms that the neon tube 33 is lit and that the flash emission is ready. After confirming the lighting of the neon tube 33,
The photographer determines the frame by using the finder 4 and then presses the shutter button 9 to perform photographing. When the shutter button 9 is pressed, the shutter operates, and the trigger switch 43 is turned on at the moment when the shutter is fully opened. When the trigger switch 43 is turned on, the flash emission switching switch 12a is turned on, so that the primary side trigger circuit is closed and the trigger capacitor 41 is discharged. A current resulting from this discharge flows in the primary coil 42a of the trigger transformer 42, a trigger voltage is generated in the secondary coil 42b, and this trigger voltage is applied to the trigger electrode 32a. As a result, the electric charge of the main capacitor 31 is discharged between both electrodes of the strobe discharge tube 32, the strobe discharge tube 32 emits light, the strobe light is emitted from the strobe light emitting section 6, and stroboscopic photography is performed.

On the other hand, when the main condenser 31 is charged and the stroboscopic light emission is possible, but when the user does not want to use the stroboscopic light emission for photographing, the photographing is performed in a place where the stroboscopic photographing is prohibited, for example, in a museum or a temple. However, the control transistor 24 or the like malfunctions due to the noise generated when the operation button 7 is already pressed or when the trigger voltage is generated in the previous flash photography, and the main capacitor 31 is charged. If the flash is in a state where the flash can be emitted against the photographer's intention, the flash emission prohibition button 12 is pressed, and the shutter button 9 is operated while keeping this state to shoot. I do.

At this time, the flash emission prohibition button 12
Is placed in a position that does not interfere with the holding posture of the left-handed and right-handed strobe film units.
It is possible to easily press the shutter button 9 while pressing the strobe light emission prohibition button 12.

When the shutter button 9 is pressed to activate the shutter and the shutter is fully opened, the trigger switch 43
Is turned on, but at this time, the state where the strobe light emission prohibition button 12 is pressed is maintained and the strobe light emission changeover switch 12a is turned off, so the primary side trigger circuit does not become a closed circuit. Therefore, the charged trigger capacitor 31 does not discharge. As a result, no current flows in the primary coil 42a of the trigger transformer 42,
Since the trigger voltage is not generated in the secondary coil 42b, the electric charge charged in the main capacitor 31 is not discharged in the strobe discharge tube 32, and the strobe discharge tube 32 does not emit light.

Whether or not strobe light emission is possible can be confirmed by turning on the neon tube 33. However, even if the charging voltage of the main capacitor 31 does not reach the specified charging voltage, that is, neon light is emitted. Even if the tube 33 is not lit, the strobe discharge tube 32 may emit light even though the light emission amount is not the normal amount. Therefore, when the photographer wants to prohibit the stroboscopic light emission, the photographer determines whether or not the neon tube 33 is lit. Regardless, it is preferable to shoot while pressing the strobe emission prohibition button 12.

As described above, even if the main capacitor 31 is charged and the stroboscopic light emission is possible, if the stroboscopic photography is not desired, the shutter button 9 is pressed while the stroboscopic light emission prohibition button 12 is pressed. By pressing the button, it is possible to shoot without flashing. Further, since the trigger capacitor 41 and the main capacitor 31 are not discharged when shooting is performed with the strobe light emission prohibited, power is not wasted and re-charging is not necessary, so that the next flash shooting is performed quickly. be able to.

In the strobe circuit shown in FIG. 4, the trigger transformer 41 is discharged by discharging the trigger capacitor 41 with a discharge resistor.
By preventing the discharge current from flowing to the second terminal, the stroboscopic light emission is prohibited. It should be noted that, except for the following description, it is the same as the above embodiment, and the same members are denoted by the same reference numerals.

A trigger switch 43 and a trigger capacitor 41 connected in series are connected between one end and the other end of the primary coil 42a of the trigger transformer 42. The trigger switch 43 and the trigger capacitor 41 are connected to the primary coil 42a in synchronization with the operation of the shutter. A primary-side trigger circuit that allows a discharge current to flow is formed. Further, the trigger capacitor 42 is connected with a discharge resistor 60 and a strobe light emission changeover switch 12b which are connected in series between both terminals of the trigger capacitor 42 to form a discharge circuit. The flash emission changeover switch 12b is a flash emission prohibition button 12
The switch is a self-reset type switch that is turned on when is pressed, and is self-restored to be turned off when the press is released. In this strobe circuit, the strobe light emission changeover switch 12b is in a light emission prohibiting position where the ON state is prohibited, and a OFF state is a light emission position where a trigger voltage is applied to the strobe discharge tube 32 to allow the strobe light emission. is there.

The flash emission changeover switch 12b is turned on.
Then, the discharging circuit becomes a closed circuit, and the electric charge charged in the trigger capacitor 41 is instantaneously discharged by the discharging resistor 60. Then, the flash emission changeover switch 1
While 2b is ON, trigger capacitor 41
Is always discharged, so that the trigger capacitor 41 is prevented from being charged. As a result, when the flash emission changeover switch 12b is ON,
Even if the trigger switch 43 is turned on, the discharge current of the trigger capacitor 41 causes the primary coil 42 of the trigger transformer 42.
It does not flow to b, and the trigger voltage is not generated in the secondary coil 42b. Moreover, since the trigger capacitor 41 has a small capacity, a small one having a small rated power can be used as the discharging resistor 60. The neon tube 33 is connected to both terminals of the main capacitor 31 via resistors 33a and 43a.

The operation of this strobe circuit will be briefly described. When taking a flash image, the operation button 7 on the front surface of the film unit with a flash is pressed without pressing the flash emission prohibition button 12 to turn on the flash charging switch 7a. As a result, the booster 20 starts to operate, and the main capacitor 31 and the trigger capacitor 41 are charged. The photographer uses the main condenser 3
1 is charged to the specified charging voltage, neon tube 33
After confirming by lighting, the shutter button 9 is pressed to take a picture. When the shutter button 9 is pressed to operate the shutter and the shutter is fully opened, the trigger switch 43 is turned on and the primary side trigger circuit is closed.

At this time, since the strobe light emission changeover switch 12b is turned off because the strobe prohibition button 12 is not pressed, the trigger capacitor 41 charged at the moment when the trigger switch 43 is turned on is discharged and discharged. Current flows in the primary coil. As a result, a trigger voltage is generated in the secondary coil 42b, and this trigger voltage is applied to the strobe discharge tube 32 via the trigger electrode 32a. Then, the main connector 31 is discharged, and the strobe discharge tube 32 emits light.

On the other hand, the main capacitor 31 is charged,
If the flash firing is possible but the flash firing is not desired for shooting, the flash firing prohibition button 12 is pressed in the same manner as in the above-described embodiment, and the shutter button is pressed while maintaining this state. The photograph is taken by pressing the button 9.

When the strobe light emission prohibition button 12 is pressed, the strobe light emission changeover switch 12b is turned on.
As a result, the discharging circuit becomes a closed circuit, the electric charge charged in the trigger capacitor 41 flows into the discharging resistor 60, and the trigger capacitor 41 is instantaneously discharged. At this time, the main capacitor 31 is in a state in which both terminals thereof are connected via the resistor 43a, the discharging resistor 60, and the strobe light emission changeover switch, but since the resistance value of the resistor 43a is large, The amount of discharge of the main capacitor 31 is extremely small, and in the next stroboscopic photography, recharging is unnecessary or even if charging is necessary, the charging time can be extremely shortened. The charging voltage of the main capacitor 31 is applied to the trigger capacitor 41 via the resistor 43a. However, since the strobe light emission changeover switch 12b is ON, the trigger capacitor 41 is charged. Without being discharged, the discharge state (non-charged state) is maintained.

In this way, the trigger capacitor 41 is momentarily discharged, and while the discharge state is maintained, the shutter button 9 is pressed to operate the shutter, and when the shutter is fully opened, the trigger switch 43 is opened. Turns on. Even if the trigger switch 43 is turned on, no current flows in the primary side trigger circuit, that is, the primary coil 42a, because the trigger capacitor 41 is in the discharged state.
Therefore, since the trigger voltage is not generated in the secondary coll 42b, the main capacitor 31 is not discharged and the strobe discharge tube 32 does not emit light.

In this way, shooting is performed with the strobe emission prohibited. In this strobe circuit, since only the trigger capacitor 41 is discharged, the trigger capacitor 4 having a small capacity is used in the next strobe photographing.
Only one needs to be charged, and the next stroboscopic photography can be performed quickly.

In the above embodiments, the strobe-equipped film unit is described, but the present invention can also be applied to a compact camera or the like.

[0052]

As described above, according to the strobe circuit of the first aspect, the trigger circuit for applying the trigger voltage to the strobe discharge tube responds to the operation of the external operation member by the trigger circuit.
Since a changeover switch that switches between a light emission position that allows the trigger voltage to be applied to the strobe discharge tube and a light emission prohibition position that blocks the application of the trigger voltage is provided,
Even if the main capacitor is charged and the flash can be fired, it is possible to prevent the flash from firing.

According to the strobe circuit of the second aspect, when the strobe light emission changeover switch of the trigger circuit is switched to the light emission prohibition position, the discharge of the trigger capacitor charged together with the main capacitor is prohibited, and the trigger transformer has the trigger capacitor. Since the discharge current from the device does not flow and the application of the trigger voltage to the strobe discharge tube is blocked, strobe light emission can be prohibited without discharging the trigger capacitor and the main capacitor, and recharging is possible. It is possible to quickly perform the next strobe light emission without needing to do so, and to eliminate unnecessary power consumption.

According to the strobe circuit of the third aspect, when the changeover switch is changed to the light emission prohibition position,
Since the lighting of the neon tube that indicates the completion of charging of the main capacitor is prohibited, the neon tube does not light when the flash firing is prohibited, so check with the neon tube whether or not the flash firing is prohibited. You can

According to the strobe circuit of the fourth aspect, when the changeover switch is switched to the light emission prohibition position, the discharge current of the trigger capacitor is caused to flow through the discharge resistor to bring the trigger capacitor into the discharge state, and the trigger transformer is discharged. Since the discharge current does not flow to the terminal and the application of the trigger voltage to the strobe discharge tube is blocked, the unnecessary power consumption is reduced and the time required for recharging is shortened.
You can prohibit the flash from firing.

According to the strobe circuit of the fifth aspect, the changeover switch is a self-reset type switch, and the strobe light is prohibited only when the external operating member is pressed, so that stroboscopic light emission is prohibited. It is possible to prevent the trouble that the strobe is not fired even if you forget the and charge the main capacitor.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a strobe circuit embodying the present invention.

FIG. 2 is a perspective view showing a front side of a film unit with a built-in strobe lens.

FIG. 3 is a perspective view showing the back side of a film unit with a built-in strobe lens.

FIG. 4 is a circuit diagram showing a strobe circuit of an embodiment in which a trigger capacitor is discharged to prohibit strobe light emission.

[Explanation of symbols]

 7 Operation Button 7a Strobe Charge Switch 9 Shutter Button 12 Strobe Flash Off Button 12a, 12b Strobe Flash Changeover Switch 20 Booster Section 30 Charging / Lighting Section 31 Main Capacitor 32 Strobe Discharge Tube 32a Trigger Electrode 33 Neon Tube 40 Trigger Circuit 41 Trigger Capacitor 42 Trigger transformer 43 Trigger switch

Claims (5)

[Claims] 1. A strobe circuit for causing a strobe discharge tube to emit light by a discharge current from a main capacitor by applying a trigger voltage generated by a trigger circuit to the strobe discharge tube, wherein the trigger circuit triggers the strobe discharge tube. A changeover switch movable between a light emission position that allows voltage application and a light emission inhibition position that blocks application of a trigger voltage is provided, and this changeover switch emits light in the light emission position and in response to the operation of an external operation member. A strobe circuit characterized in that it is possible to select whether light emission of a strobe discharge tube is required or not by switching to a prohibited position. 2. The trigger circuit includes a trigger capacitor that is charged when the main capacitor is charged and a trigger transformer that generates the trigger voltage by a discharge current of the trigger capacitor, and switches the changeover switch to a light emission prohibition position. The strobe circuit according to claim 1, wherein discharge of the trigger capacitor is prohibited by. 3. The strobe circuit according to claim 1, wherein lighting of a neon tube indicating that charging of the main capacitor is completed is prohibited by switching the changeover switch to a light emission prohibition position. . 4. The trigger circuit includes a trigger capacitor charged along with charging of a main capacitor, and a trigger transformer for generating the trigger voltage by a discharge current of the trigger capacitor, and switches the changeover switch to a light emission prohibiting position. 2. The strobe circuit according to claim 1, wherein the trigger capacitor is discharged by a discharge resistor so that the discharge current does not flow in the trigger transformer. 5. The switch according to claim 1, wherein the changeover switch is a self-reset type switch, and the changeover switch is changed over to a light emission inhibition position only when the external operation member is pressed. Strobe circuit.