JPS60220323A - Stroboscope device - Google Patents

Abstract

PURPOSE:To obtain a stroboscope device which attains a proper quantity of emitted light in accordance with photographic conditions without a dimming circuit, by connecting plural capacitors in parallel to a flash discharging tube and providing switching means for charging circuits and discharging circuits of individual capacitors respectively and controlling organically these means on the basis of film sensitivity information and photographic distance information. CONSTITUTION:Capacitors 3-6 are connected in parallel to a flash discharging tube 1, and they are charged by an oscillating current from a boosting circuit 7. Thyristors 11-14 as switching elements for charging control are connected to earth-side terminals of capacitors 3-6, and these thyristors are made conductive to charge corresponding capacitors 3-6. Discharging circuits of capacitors 3-6 are provided with thyristors 15-18 as switching means for discharging control, and discharging of capacitors 3-6 is determined by conduction or non-conduction of these thyristors. Thus, the charging voltage is controlled in accordance with the film sensitivity, and all of the electric energy stored in capacitors 3-6 is used for light emission.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention connects a plurality of capacitors in parallel to a flash discharge tube, and selects these capacitors according to photographing conditions to obtain an appropriate amount of light emission. This invention relates to a strobe device.

[Prior art]

Strobe devices that provide artificial lighting to the subject are
Various types have been put into practical use so far. Among them,
An automatic light control strobe that uses a light control circuit to integrate the amount of light reflected from the subject from the time the strobe starts firing, and shuts off the strobe when this integrated value reaches a predetermined value. is widely used because it is easy to operate and obtain proper exposure.

However, among the autoflash control strobes, those using a parallel control method are disadvantageous in terms of power saving, and those using a series control method tend to overexpose when the photographing distance becomes short. When shooting with a film that has a narrow range of proper exposure, such as instant film, the exposure may exceed the film's tolerance and become unusable. . Furthermore, all of these automatic light control strobes require an expensive light control circuit, which increases costs.

On the other hand, as is known from, for example, Japanese Patent Application Laid-open No. 57-195229, a plurality of capacitors are connected in parallel to a flash discharge tube and these are selectively used to save power.
Alternatively, some devices control the amount of light emitted. However, such strobes require a dimming circuit, or the amount of light emitted is determined in advance by the number of combinations of the plurality of capacitors without using a dimming circuit.
There is a drawback that, for example, when changing the shooting distance after charging the capacitor, proper exposure cannot be obtained.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional technology, and an object of the present invention is to provide a strobe device that can obtain an appropriate amount of light emission according to shooting conditions without using a light control circuit. .

[Structure of the invention]

In order to achieve the above object, in the present invention, a plurality of capacitors are connected in parallel to a flash discharge tube, switching means are provided in the charging circuit and discharging circuit of these capacitors, respectively, and these switching means are connected to the film sensitivity information and the shooting distance. It is an object of the present invention to provide a strobe device that obtains an appropriate amount of light emission through organic control based on information.

[Configuration of Example]

In FIG. 1 showing one embodiment of the present invention, a flash discharge tube 1
Capacitors 3 to 6 for supplying discharge current to the flash discharge tube 1 are connected in parallel to the flash discharge tube 1. These capacitors 3 to G are charged by an oscillating current from a booster circuit 7 comprising, for example, a blocking oscillator. This booster circuit 7 is activated when a strobe power switch 8 connected in series to a power source 9 is turned on. Cyrisks 11 to 14 are connected to the ground side terminals of the capacitors 3 to 6 as switching elements for charging control, and depending on whether or not each Cyrisk 11 to 14 is conductive, the corresponding capacitor 3 to 6 will be selected and charged.

The connection paths between the capacitors 3 to 6 and the flash discharge tube 1, that is, the discharge circuits of the respective capacitors 3 to 6 are equipped with Cyrisks 15 to 18 as switching elements for discharge control.
is provided. Therefore, each capacitor 3~
The discharge of 6 is selectively determined depending on whether or not these cyrisks 15 to 18 are made conductive.

The respective gate terminals of the cyrisks 11-14 are connected to the output terminals of the comparators 2I-24, and the respective gate terminals of the thyrisks 15-18 are connected to the respective ignition circuits 55-58 by pulse transformer coupling. . The ignition circuits 55 to 58 each include capacitors 51 to 54 and cyrisks 61 to 64.

And the gate terminals of these Cyrisks 61 to 64 are
It is connected to the output ends of comparators 25-28.

The threshold voltages of the comparators 21 to 24 are determined by a voltage divider 30.
Accordingly, comparator 21 is the lowest, and comparator 2
4 is the highest, i.e. vl<V2<V3
<V4. Similarly, the comparators 25 to 28 are set by the voltage divider 32 so that the comparators 25 and 16 are also the lowest, and the comparator 28 is the highest (i.e., v5<v6<V7<V8. The pressure device 32 is configured to operate each of the comparators 25 to 28 by a switch 5o that is turned on in conjunction with an X contact 4o that operates a trigger circuit 38, which will be described later.

The output ends of an operational amplifier 34 are connected to the input ends of the comparators 21-24, and the output ends of an operational amplifier 35 are connected to the input ends of the comparators 25-28. The operational amplifier 34 outputs a voltage corresponding to the resistance value of a variable resistor 36 that is varied in conjunction with the film sensitivity setting operation, and the operational amplifier 35 outputs a voltage that corresponds to the resistance value of a variable resistor 36 that is varied in conjunction with the shooting distance setting operation. It is configured to output a voltage according to the resistance value of 37. Further, the trigger circuit 38 is connected to an X
The contact 40 is actuated to trigger the flash discharge tube l to emit light. Note that the diodes 42 to 44 connected in series with the cyrisks 11 to 14 are used to regulate the discharge paths of the respective capacitors 3 to 6. Diodes 46 to 49, which have a flow blocking effect and are connected in parallel in opposite directions to the silices 11 to 14, are provided to form a discharge circuit for the respective capacitors 3 to 6.

[Effect of the embodiment]

According to the above configuration, first, when the film sensitivity of the film loaded in the camera is low, the resistance value of the variable resistor 36 becomes high, and therefore the output voltage Va from the operational amplifier 34 increases.
becomes higher. For example, when Va>V4, the comparators 21 to 24 all generate signal voltages, and the ignition voltage is applied to all of the cyrisks 11 to 14, so
When the strobe power switch 8 is turned on, the booster circuit 7 is activated, and a charging current flows, all of the Cyrisks 11 to 14 are turned on and all of the capacitors 3 to 6 are charged, and the flash discharge tube 1 is turned on. The charging voltage required to cause the light to emit light becomes higher. Incidentally, due to the operation of the ascending Y-motor circuit 7, the respective capacitors 51 to 54 of the ignition circuits 55 to 58 are also charged.

On the other hand, when the film used has a high film sensitivity,
The resistance value of the variable resistor 36 is low, and therefore the output voltage of the operational amplifier 34 is also low. Then, when V2<Va<Va, the comparators 21 and 22 are activated, and the cyrisk 1
The ignition voltage is applied only to 1.12. Therefore, in this case, even if the booster circuit 7 operates, only the thyristors II and 12 become conductive and the capacitors 3 and 4 are charged, so the charging voltage required to cause the flash discharge tube 1 to emit light is lower than that in the above case. will also be lower.

From the above, it becomes possible to control the charging voltage according to the film sensitivity of the film used. That is,
If the film sensitivity is low and a large amount of strobe light is required, the charging voltage should be increased accordingly, and if the film sensitivity is low and a small amount of strobe light is required, the charging voltage should be reduced. It acts on

After the film is charged in accordance with the film sensitivity, a photographing operation is performed, but before the camera's shirt release is performed, the photographing distance is first adjusted. The shooting distance is adjusted by extending the lens barrel, and the resistance value of the variable resistor 37 changes depending on the amount of extension of the lens barrel. That is, the farther the photographic lens is adjusted, the higher the resistance value of the variable resistor 37 is changed. When the resistance value increases, the output voltage vb from the operational amplifier 35 also increases, and for example, when Vb>V8, shirt release is performed and
When the contact 4o is turned on and the trigger circuit 38 is activated,
At the same time, the voltage divider 32 operates, and the comparators 25 to
28 all output signal voltages. As a result, ignition voltage is applied to the gate terminals of Cyrisks 61 to 64,
Since these are electrically connected, a discharge current from the capacitors 51 to 54 flows in each of the ignition circuits 55 to 58. When a discharge current flows through the ignition circuits 55 to 58, the cyrisks 15 to 18 connected by the pulse transformer
An ignition current is supplied to the gate terminals of , so that cyrisks 15 to 18 are conductive. Therefore, capacitors 3 to 6
Since a discharge circuit will be formed for all of
All of the electrical energy stored in each of the capacitors 3 to 6 is used for light emission.

Further, the shooting distance is set to the short distance side, the resistance value of the variable resistor 37 becomes low, and the output voltage vb of the operational amplifier 35 becomes V
When 6<Vb<■7, even if the voltage divider 32 is activated by turning on the switch 5o, only the comparator 25.26 generates a signal voltage, which causes the si risk 61.62
Only that will be conductive. Therefore, thyristor 15
．． 16 is conductive, but the other cyrisks 17 and 18 remain cut off, and only the electrical energy stored in capacitor 3.4 is used for light emission, while the electrical energy stored in capacitor 5.6 remains unchanged. This allows the amount of light emitted to be kept low.

In this way, when the shutter release is performed after the shooting distance has been adjusted, the trigger circuit 38 is activated, and at the same time, one of the capacitors selected and charged according to the film sensitivity is activated at the distance opening. Since the capacitor selected according to the above conditions supplies a discharge current to the flash discharge tube 1, appropriate illumination light is provided to the subject. Even just before shirt release, if the shooting distance is changed, the capacitor used for light emission is reselected accordingly, so an appropriate amount of light can be obtained taking into account the shooting distance information. It becomes like this. Note that a capacitor that is not used for emitting light during photographing has residual charge, which can be used for subsequent photographing. Further, when charging is completed and the charging current reaches the holding current limit of the cyrisks 11 to 14, the cyrisks 11 to 14 are turned off, so that power consumption is reduced.

In the above embodiments, the switching element provided for the charging circuit or the discharging circuit may be replaced by not only a semiconductor switching element such as a SIRISK or a power transistor, but also other elements. For example, a sliding section and a brush may be provided between a fixed part and a movable part of a film sensitivity setting part or a lens barrel part for distance adjustment, which are selectively connected depending on the setting or adjustment position, respectively. Directly turn on the switch inserted in series for each capacitor charging circuit or discharging circuit.
It may be turned off, or turned on and off via a relay.

〔Effect of the invention〕

As described above, in the present invention, when controlling the amount of light emitted by the strobe, the charging amount is determined based on the film sensitivity information, and then the discharging amount is controlled using the distance information. Overexposure when shooting at close range, which often occurs with devices, has been resolved and the film sensitivity has been improved.

It is possible to obtain a light emission amount that is suitable for the shooting distance.

What's more, the electrical energy that is not used during charging can be used for subsequent shooting, resulting in a power saving effect.

Also, compared to using a dimming circuit which is structurally complex, it is advantageous in terms of cost and assembly adjustment.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing one embodiment of the present invention. l... Flash discharge tube 3-6... Capacitor 7... Boost circuit 11-14... Cyrisk 15-18... Cyrisk 21-24... Comparator 25-28... Comparator 30... Voltage divider 32. -Voltage divider 36...Variable resistor 37...Variable resistor 38...Trigger circuit 55-58...Ignition circuit.

Claims (3)

[Claims] (1) a plurality of capacitors each connected in parallel to the flash discharge tube in order to supply a discharge current to the flash discharge tube; and charging control switching means provided in each of the charging circuits of the plurality of capacitors; discharging control switching means provided in each of the discharge circuits of the plurality of capacitors, and charging a predetermined one of the plurality of capacitors by controlling the charge control switching means based on film sensitivity information; Further, a strobe device characterized in that a predetermined one of the plurality of capacitors can be discharged by controlling the discharge control switching means based on photographing distance information. (2) The strobe device according to claim 1, wherein the charging control switching means or the discharging control switching means is constituted by Cyrisk. (3) The strobe device according to claim 2, wherein the gate terminal of the cyrisk is connected to a control means that outputs a conduction signal in accordance with film sensitivity information or photographing distance information.