JPH04114136A - Flash light emission control circuit - Google Patents

Abstract

PURPOSE:To efficiently control the light emission of plural discharging tubes without enlarging the scale of a control circuit by using the gate control type switching elements of plural light emission discharging tubes and a gate electrode control means controlling the conductive states of switching elements, in common. CONSTITUTION:In a gate control type first switching element 14 as the gate control type switching element, a bias voltage is applied on a gate electrode 14g, so that conducting is carried out between a collector 14c and an emitter 14e, and the application of the voltage to the gate electrode 14g is interrupted, so that the conduction is not carried out between them. A Zener diode 17 for obtaining a voltage enough to carry out the conduction with respect to the gate electrode 17g and not to carry out the voltage breakdown of the gate electrode 14g is connected between the gate electrode 14g and the emitter 14e. On the other hand, a second switching element 18 composed of a transistor shunting the gate of the first switching element 14 is connected in parallel to the Zener diode 17. Thus, the light emission of respective discharging tubes can be carried out by a small-scale circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a light emission control circuit for a strobe, and more particularly, to a light emission control circuit for a strobe, which controls the light emitting operation and light emitting stop operation of each light emitting discharge tube in a strobe device having a plurality of light emitting discharge tubes. This invention relates to a control circuit that performs operations efficiently.

[Prior Art] A means for controlling the light emission of a plurality of light-emitting discharge tubes in a strobe (flash light emitting device) used for photography is disclosed in Japanese Patent Application Laid-Open No. 57-173826.

The multi-flash strobe control device disclosed in Japanese Patent Application Laid-Open No. 57-173827, and the control device of Japanese Patent Application Laid-open No. 1-260425,
A strobe device having a plurality of light emitting discharge tubes is disclosed in Japanese Utility Model Application Publication No. 1-155034.

The above multi-flash strobe control device uses a plurality of strobe devices, sets the light intensity ratio of each strobe device in advance, and when the light intensity of one strobe device reaches a predetermined light intensity, A set light quantity ratio is obtained by stopping the flash light emission of the strobe device and starting light emission of the other flash flash devices.

In addition, in the above strobe device having a plurality of discharge tubes, for example, two discharge tubes for light emission are arranged in one strobe device, and when the subject is an animal, one discharge tube is used to prevent the red eye phenomenon of the subject. A preliminary flash is performed to reduce the amount of light emitted before photographing, and then the main flash is performed using the other discharge tube to perform flash synchronized photographing.

[Problems to be Solved by the Invention] However, in the conventional multi-flash strobe control device described above, the trigger circuit 9 is a light emission control circuit for controlling the light emission of the discharge tubes in each strobe device.

A control circuit such as a light emission stop circuit is required for each discharge tube, which not only increases the scale of the circuit but also increases the number of control signal lines.

Furthermore, even in the conventional strobe device having a plurality of discharge tubes, when two discharge tubes are used to perform red-eye prevention light emission and main light emission, the discharge tubes used for each light emission are determined in advance. Therefore, even if two discharge tubes with different irradiation angles are provided, only one discharge tube is always used for the main emission, and it is not possible to use either discharge tube to perform the main emission at will. However, the range of use was limited and the discharge tube could not be used effectively.

SUMMARY OF THE INVENTION An object of the present invention is to provide a strobe light emission control circuit that eliminates the drawbacks of the conventional strobe device having a plurality of light emission discharge tubes and can control the light emission of each discharge tube with a small-scale circuit. be.

[Means and effects for solving the problems] In order to achieve the above object, the strobe light emission control circuit according to the present invention includes a booster circuit including a power supply, a main capacitor charged by the output of the booster circuit, and a main capacitor charged by the output of the booster circuit. corresponds to a plurality of light-emitting discharge tubes connected in parallel, and a trigger electrode of the light-emitting discharge tube in response to a light emission start signal for each light-emitting discharge tube. a plurality of trigger means for applying a starting voltage to excite the discharge tube to a conductive state;
A gate-controlled first switching element consisting of a gate-insulated bipolar transistor connected in series in the discharge path of the main capacitor including the plurality of light-emitting discharge tubes, and a gate electrode of the first switching element. A voltage is applied to turn the first switching element into a conductive state, and in response to the light emission stop signal, the voltage application to the gate electrode is stopped, and the first switching element is returned to a non-conductive state jf! gate electrode control means including two switching elements.

[Example] The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 is an electrical circuit diagram of a light emission control circuit of a strobe device showing a first embodiment of the present invention. The light emission control circuit of this embodiment is configured to control the light emitting operation and light emitting stop operation of the two discharge tubes, the first light emitting discharge tube 1 and the second light emitting discharge tube 2. .

This light emission control circuit supplies high voltage necessary for discharging the first light-emitting discharge tube 1 and the second light-emitting discharge tube 2.
A main capacitor 4 that stores the charge necessary for light emission supplied from the booster circuit 3 including a power source, and a series circuit of a resistor 51 and a first thyristor 6 for triggering the start of light emission are each connected in parallel. A series circuit consisting of a gate-controlled first switching element 14 connected in series to the first and second light-emitting discharge tubes 1.2 and a second thyristor 10 for triggering the start of light emission with a 9° resistor. The series circuit is
The main capacitor 4 is connected to the main capacitor 4 through a backflow prevention diode 27, respectively.

The first trigger thyristor 6 is turned on when the light emission starting voltage Va is applied to its gate from the input terminal 19, and operates the first trigger circuit. A first trigger capacitor 7 whose one end is connected to the connection point between the resistor 5 and the thyristor 6 and whose other end is connected to the primary winding of the trigger transformer 8, and the secondary winding or the trigger electrode 1t of the first discharge tube 1. A first trigger transformer 8 is connected to the first trigger transformer 8 and generates a high voltage pulse for excitation to be applied to the electrode 1t, and the primary winding of the trigger transformer 8 transfers the charge accumulated in the capacitor 7 when turned on. The first thyristor 6 discharges electricity through the wire.

Similarly, the second trigger thyristor 10 is turned on when the light emission starting voltage Vc is applied to its gate from the input terminal 20 to operate the second trigger circuit. A second trigger capacitor 11 has one end connected to the connection point between the resistor 9 and the thyristor 10, and the other end connected to the primary winding of the trigger transformer 12, and the secondary winding is connected to the second discharge. a second trigger transformer 12 that is connected to the trigger electrode 2t of the tube 2 and generates a high voltage pulse for excitation to be applied to the trigger electrode 2t;
The second thyristor 10 discharges the charge accumulated in the capacitor 11 through the primary winding of the trigger transformer 12 when turned on.

The gate-controlled first switching element 14
For example, there is a gate insulated bipolar transistor called IGBT.
polar Transistor) is used. When a bias voltage is applied to the gate electrode 14g of this switching element, the collector 14c
This is a gate-controlled switching element that conducts between the gate electrode 14g and the emitter 14e, and becomes non-conductive when the voltage application to the gate electrode 14g is cut off. A Zener diode 17 is connected to obtain a voltage that is sufficient for conduction and does not cause voltage breakdown of the gate electrode 14g.

In addition, the collector 14C of the first switching element 14
, and the emitter 14e, a capacitor 15 for storing charges for gate bias is connected via a diode 13, and the charges stored in the capacitor 15 apply a bias voltage to the gate electrode 14g through a resistor 16. It looks like this. The diode 13 serves to charge the capacitor 15 with the discharge current of the light emitting discharge tube 1 or 2, and to prevent the charge in the capacitor 15 from being discharged through the switching element 14 even after the switching element 14 is turned on. be.

Further, a second switching element 18 consisting of a transistor that shunts the gate of the first switching element 14 is connected in parallel to the Zener diode 17. When the second switching element 18 stops emitting light, a light emitting stop voltage vb is applied to its base from the input terminal 21 and the second switching element 18 is turned on. It serves to keep the voltage below the level at which it becomes conductive.

Next, the operation of the light emission control circuit of the first embodiment configured as described above will be explained with reference to the time chart of FIG. 2.

When a power switch (not shown) is turned on, the main capacitor 4 is charged with enough charge to cause the discharge tubes 1 and 2 to emit light by the output of the booster circuit 3. In this state, the trigger capacitor 7.11 is also charged with the same voltage through the resistors 5 and 9, respectively.

Here, a case will be described in which the light-emitting discharge tube 1 is first made to emit light, and immediately after that, the light-emitting discharge tube 2 is made to emit light. First, the light-emission starting voltage Va is applied to the input terminal 19. That is, a voltage necessary for turning on the first thyristor 6 is applied to the gate of the first thyristor 6 by the light emission starting voltage Va applied to the circuit system for causing the discharge tube 1 to emit light. Then, the thyristor 6 is turned on, the charge in the capacitor 7 flows through the primary winding of the trigger transformer 8, a high voltage pulse voltage is generated in the secondary winding, and this high voltage pulse VTL for excitation is applied to the discharge tube 1. is applied to the trigger electrode It. The discharge tube 1 is excited by this high voltage pulse VtI and becomes conductive. At this time, the first switching element 14 is not yet conductive,
The current discharged from the main capacitor 4 through the discharge tube 1 charges the capacitor 15 through the diode 13, and when the terminal voltage rises, the voltage generated by the Zener diode 17 is applied to the gate electrode 14g of the first switching element 14 through the resistor 16. , the first switching element 14 becomes conductive, and the current I flowing through the discharge tube 1,
1 flows from the collector 14c to the emitter 14e, and the discharge light emission continues.

In addition, the voltage Vd of the collector 14c that has increased when the first light-emitting discharge tube 1 becomes conductive is reduced to a few volts or less when the first switching element 14 is turned on, but is stored by the capacitor 15. The discharged charges are prevented from being discharged through the first switching element 14 by the diode 13.

Then, when a light emission stop voltage vb for stopping light emission is applied to the input terminal 21 after emitting light for an arbitrary period of time, the second switching element 18 is immediately turned on, and the gate electrode 14g of the first switching element 14 is turned on. The voltage of
The switching element 14 becomes non-conductive, the current path flowing through the first discharge tube 1 is cut off, and the first light-emitting discharge tube 1 stops emitting light. The light emission stop signal to the second switching element 18 is released after the first discharge tube 1 is turned off.

Next, the first discharge tube 1 is caused to emit light for an arbitrary period of time, and after the light emission is stopped, the second light-emitting discharge tube 2 is caused to emit light.

In this light emission operation, the light emission starting voltage Vc is applied to the input terminal 20, as in the case of the first discharge tube 1 described above. In other words, the light emission starting voltage Vc to the circuit system for causing the discharge tube 2 to emit light
A voltage required for turn-on is applied to the gate of the second thyristor 10. Then, the second thyristor 1
0 is turned on, the charge in the trigger capacitor 11 flows to the primary winding of the second trigger transformer 12, thereby generating a high voltage pulse voltage in the secondary winding, and this trigger pulse vt2 is applied to the second discharge tube 2. is applied to the trigger electrode 2t.

The second discharge tube 2 is excited by the pulse voltage Vt2 and becomes conductive. At this time, the first switching element 14 is in a conductive state due to the light emission stop voltage vb which is the previous light emission stop signal, but since the application of the light emission stop voltage vb has already been released at this time, the first switching element 14 The same circuit operation as described above regarding the light emitting operation of the discharge tube 1 for light emission is performed, and finally the first switching element 14 becomes conductive, and the second discharge tube 2 continues to discharge and emit light.

When the light emission is to be stopped after emitting light for an arbitrary period of time, a light emission stop voltage vb, which is a light emission stop signal, is applied to the input terminal 21. Then, the second switching element 18
turns on, the voltage of the gate electrode 14g of the first switching element 14 decreases, the switching element 14 becomes non-conductive, the current path flowing through the second discharge tube 2 is cut off, and the current path flowing through the second discharge tube 2 is cut off. Light emission stops. The application of the light emission stop voltage vb, which is the light emission stop signal, to the second switching element 18 is released after the second discharge tube 2 stops emitting light.

After the second discharge tube 2 becomes conductive in this manner, the circuit operation until it stops emitting light is performed in exactly the same manner as in the case of the first discharge tube 1 described above.

Furthermore, in the description of the first embodiment, the second discharge tube 2 is made to emit light after the first discharge tube 1 is made to emit light, but there is no particular restriction on this order; , 1st
Needless to say, the discharge tube 1 may be caused to emit light, and the light emission may be repeated any number of times until the residual voltage of the main capacitor 4 after the light emission stops becomes lower than the minimum voltage necessary for the discharge tube to emit light.

FIG. 3 shows a second embodiment of the invention. The control circuit of this second embodiment is obtained by adding a voltage doubler circuit to the control circuit of the first embodiment. That is, this voltage doubler circuit includes the cathodes of the first and second light-emitting discharge tubes 1.2 connected in parallel and the first switching element 1.
A diode 24 is connected between the collectors 14c of the four collectors 14c with the cathode across the collector 14c, and a first capacitor 22 for voltage doubling is connected between the anode of the diode 24 and the anode of the first trigger thyristor 6. A second capacitor 23 for voltage doubling is connected between the anode of the diode 24 and the anode of the second trigger cyrisk lO.
A resistor 25 is connected between the anode of the diode 24 and the emitter 14e of the first switching element 14, and a capacitor 26 is connected in parallel to the resistor 16. Since the other circuit configurations are exactly the same as those of the first embodiment, the same components are given the same reference numerals and their explanations will be omitted.

The voltage doubler circuit having the first and second voltage doubler capacitors 22 and 23 has a charging voltage of the main capacitor 4 across the discharge tube 1 or 2 when the first thyristor 6 or the second thyristor 10 is turned on. This circuit applies a voltage approximately twice that of the voltage applied to the main capacitor 4 to facilitate discharge even if the voltage of the main capacitor 4 is below the minimum voltage at which the discharge tubes 1 and 2 can emit light. When the second thyristor 6.10 is off, the voltage doubler capacitor 22.23 is charged with the same voltage as the main capacitor 4.

When the light emission starting voltage Va, which is a light emission signal, is applied to the input terminal 19 in this state, the first thyristor 6 is turned on and the first thyristor 6 is turned on.
A high voltage pulse for excitation is applied to the trigger electrode 1t of the discharge tube 1, and the cathode of the discharge tube 1 is lowered to a negative potential. When the discharge tube 1 is excited in this manner, the discharge tube 1 becomes conductive. When the discharge tube 1 becomes conductive, the cathode instantly changes from a negative potential to a positive potential, and the current passing through the discharge tube 1 charges the capacitor 15.

The subsequent operation from turn-on to turn-off of the first switching element 14 is the same as that of the first switching element 14 explained in FIG. 1.2 above.
Since the operation is the same as that of the embodiment, the explanation will be omitted.

In the second embodiment, the operation of the voltage doubler circuit allows the light emission and stop to be repeated far more times than in the first embodiment.

Furthermore, as shown in Figure 4, even in a camera that has two main light emitting parts with different illumination angles and multiple light emitting discharge tubes, only a few additional parts are needed compared to a camera that has only one light emitting part. This makes it possible to create a strobe that can control the dimming of both lights.

That is, the camera shown in FIG. 4 is a single-lens reflex camera, and the subject light that has passed through the photographing lens 32 of the camera body 31 is reflected by the movable reflection mirror 33, and further transmitted through the pentaprism 36 to the eyepiece. be guided. On the other hand, a part of the subject light passes through the movable reflection mirror 33 and is reflected by the movable reflection auxiliary mirror 34 for AF (autofocus).
AF is performed by irradiating the light onto the light receiving surface of the focusing sensor 37a. When photographing, the movable reflection mirror 33 and the movable auxiliary reflection mirror 34 are flipped upward by a mechanism (not shown), so that the light from the object is focused on the film 35.

Further, above the camera body 31, there is a strobe light emitting section 43 that includes a telephoto strobe light emitting section 41 having one light emitting discharge tube 38 and a wide angle strobe light emitting section 42 having the other light emitting discharge tube 39. It is installed. This strobe light emitting section 43 is shown in a popped-up state by pressing the pop-up switch 40, but when stored, it is in a state 43a shown by a two-dot chain line. An external strobe shoe 44 is disposed behind the strobe light emitting unit 43 and is used when an external strobe is attached.

In this way, the present invention can also be applied to the strobe light emitting section 43 having two main light emitting sections like the above camera.

FIG. 5 shows a third embodiment of the present invention. The control circuit of these three embodiments is the same as the control circuit of the second embodiment of the present invention shown in FIG.
, third thyristor 6A, resistor 5A, trigger capacitor 7
A, a third light emitting circuit consisting of a third trigger circuit of a trigger transformer 8A and a third voltage doubler capacitor 22A, a fourth light emitting discharge tube 2A, a fourth thyristor 10A, and a resistor 9
A, the number of light emitting discharge tubes is increased by connecting the trigger capacitor IIA, the fourth trigger circuit of the trigger transformer 12A, and the fourth light emitting circuit consisting of the fourth voltage doubler capacitor 23A as shown in the figure. .

In this way, a trigger circuit consisting of discharge tubes IA, 2A, thyristor 6A, IOA, trigger transformers 8A, 12A, etc., which apply a high voltage for excitation to the discharge tubes, is further added, and By sequentially applying the light emission starting voltage Va to the two discharge tubes for four light emission from the input terminals 19.20° 19A and 2OA, it is possible to cause the plurality of discharge tubes to perform dimming light emission operation.

FIG. 6 is a timing chart when, in the control circuit shown in FIG. 3, a pulse signal voltage is repeatedly applied to the stop signal input terminal 21 to cause continuous light emission by intermittent operation.

In this case, the operation of applying the light emission start signal voltage Va to the input terminal 19 and starting light emission at the time of starting light emission is the same as described above. When stopping the light emission, a light emission stop signal voltage Vb consisting of repeated pulses is applied to the input terminal 21 to turn on the second switching element 18 and make the first switching element 14 non-conductive. At this time, the potential Vd of the collector 14c of the switching element 14
increases, and the bias capacitor 15 is charged again. While the discharge tube 1 remains active even after the current is cut off, when the application of the stop signal voltage b1 consisting of the pulse signal is removed and the second switching element 18 is turned off,
The gate potential of the first switching element 14 rises again due to the charging voltage of the capacitor 15, and becomes conductive, and light emission due to discharge of the discharge tube 1 is resumed.

No matter how short a period of time you want to repeat the discharge intermittently, if you apply a trigger signal to the first discharge tube to emit light, then no matter which discharge tube you use, you can stop the light emission by applying a pulse signal voltage to the input terminal 21. It is sufficient to simply apply the voltage vb1.

Next, FIG. 7 is a time chart when the red-eye prevention operation is performed by the control circuit shown in FIG. 1.

In this case, for example, one of the discharge tubes 1 is used to repeatedly emit red-eye prevention light several times for a short time, and then finally emit the main light for photographing. The circuit operation for one light emission is performed in exactly the same manner as described in FIG. 1 above. As for repeated light emission for red-eye prevention, the interval is sufficient time for the discharge tube 1 to stop emitting light and reach a stable state, and the light emission start signal voltage va□ is applied to the input terminal 19 every time the discharge tube 1 emits light. . The light emission is stopped by applying a pulsed light emission start signal voltage Vb2 to the input terminal 21.

Note that when performing red-eye phenomenon prevention light emission and main light emission using the other light-emitting discharge tube 2, the light emission start signal voltage Va may be similarly applied to the input terminal 20 instead of the input terminal 19.

As explained in Figures 6 and 7 above, by making it possible to individually control dimming for multiple discharge tubes and perform red-eye prevention light emission, reflectors with different illumination angles can be combined with each discharge tube. Accordingly, the same effect can be obtained without increasing the circuit size even in a strobe device that does not have a driving device such as a motor for switching the illumination angle.

FIG. 8 shows the first embodiment in the first embodiment shown in FIG.
This shows another example of the method of applying a bias voltage to the switching element 14.

The means for applying this bias voltage is the diode 13. as in the first embodiment. Bias capacitor 15. resistance 1
6, etc., and the voltage is obtained from the main capacitor 4 by using only - resistors 28. That is, the first
A current for generating the voltage is passed from the main capacitor 4 through the resistor 28 to the Zener diode 17, which generates a voltage that is sufficient for conduction to the gate electrode 14g of the switching element 14 and does not cause voltage breakdown. While the main capacitor 4 has a charge, a voltage Vg1 (see FIG. 9) sufficient to make the first switching element 14 conductive is always applied to the gate electrode 14g of the first switching element 14.

Even if the bias voltage applying means configured in this manner is employed, as shown in the time chart of FIG. When the switch is released, the charge remaining in the main capacitor 4 returns the first switching element 14 to the conductive state.

It goes without saying that if a voltage doubler circuit like the second embodiment shown in FIG. 3 is added to the control circuit shown in FIG. 8, the same effects as in the second embodiment can be obtained. do not have.

Effects of the Invention As described above, according to the present invention, since the gate-controlled switching elements of each of the plurality of light-emitting discharge tubes and the gate electrode control means for controlling the conduction state thereof are made common, the control circuit It is possible to efficiently control the light emission of multiple discharge tubes without increasing the scale of the flash unit or taking up space, and only one light emission stop signal line is required, thus eliminating the drawbacks of conventional strobe devices of this type. A removed light emission control circuit can be provided.

Furthermore, in the present invention, the light emission can be controlled in the same way for all discharge tubes, so no matter which discharge tube is used, it is possible to emit a single light emission to prevent the red-eye phenomenon, and its usage is more flexible compared to conventional ones. It also has the effect of greatly expanding the spread.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of a strobe light emission control circuit according to a first embodiment of the present invention. FIG. 2 is a time chart for explaining the operation of the light emission control circuit of the first embodiment. FIG. 4 is an electric circuit diagram of a strobe light emission control circuit showing a second embodiment of the present invention. FIG. FIG. 5 is an electric circuit diagram of a strobe light emission control circuit showing a third embodiment of the present invention, and FIG. 6 is an electric circuit diagram of a strobe light emission control circuit shown in FIG. FIG. 7 is a time chart showing the operation of the red-eye phenomenon prevention operation using the light emission control circuit shown in FIG. 1; FIG. 8 is a time chart showing the gate bias applying means of the first switching element FIG. 9, an electric circuit diagram of a light emission control circuit showing another example, is a time chart showing the operation of the light emission control circuit shown in FIG. 8. 12・・・・・・・・・Discharge tube for light emission It, 2t
・・・・・・Trigger electrode 3・・・・・・・・・・・・・・・Boost circuit 4・
・・・・・・・・・・・・・・・・ Main capacitor 30 14 ・・・・・・・・・・・ First switching element 17 ・・・...... Zener diode (gate electrode control means) 18 ...... Second switching element (gate electrode control means) 4th [

Claims (1)

[Claims] (1) A booster circuit including a power supply, a main capacitor charged by the output of this booster circuit, a plurality of light-emitting discharge tubes each connected in parallel, and a battery corresponding to each of the plurality of light-emitting discharge tubes. , a plurality of trigger means for applying a starting voltage to a trigger electrode of each light-emitting discharge tube in response to a light-emission start signal for each light-emitting discharge tube to excite the discharge tube to a conductive state; and the plurality of light-emitting discharge tubes; A gate-controlled first switching element made of a gate-insulated bipolar transistor is connected in series in the discharge path of the main capacitor including the tube, and a voltage is applied to the gate electrode of the first switching element, A gate including a second switching element that turns the first switching element into a conductive state, stops applying voltage to the gate electrode in response to a light emission stop signal, and returns the first switching element to a non-conductive state. A strobe light emission control circuit comprising: electrode control means;