JPH1048714A - Stroboscopic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform optimum stroboscopic light emission in accordance with a light emission mode by switching an inductance for limiting a light emitting current in accordance with the light emission mode. SOLUTION: A thyristor 13 is set in a cutoff condition in order to make a light emission waveform smooth in the case of flat light emission, and the light emitting current is set so as to flow through both coils 6 and 8. That is, the FP- SP control terminal of a microcomputer 38 is set to Lo, and transistors 21 and 18 are in an off condition, so that a gate on signal is not impressed on the gate of the thyristor 13. The thyristor 13 is set to be in a conductive condition in order to make the light emission waveform steep in the case of flash light emission, so that the light emitting current does not flow in the coil 8. That is, the FP- SP control terminal of the microcomputer 38 is set to Hi, the transistors 21 and 18 are in an on condition, and a bias voltage is impressed on the gate of the thyristor 13 through a resistor 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emission control device for a flash device.

[0002]

2. Description of the Related Art As shown in FIG. 7, in a light emitting circuit of a conventional flash light emitting device, an inductor is generally inserted in a light emitting / discharging circuit as shown in FIG. 7 in order to improve light emitting controllability and protect the light emitting control circuit. It is being done. The operation of the figure will be described below. In the figure, reference numeral 401 denotes a battery, and 402 denotes a battery 4.
01 is converted to a high voltage of several hundred volts, 403 is a capacitor for storing luminous energy, 404 is a Xe tube as a light emitting means, and 405 is several thousand volts to excite the Xe tube 404 during light emission. A trigger circuit for generating a high voltage, a light emission control circuit 406 controls the light emission current of the Xe tube 404, and a light emission control circuit for controlling emission start / stop of the Xe tube 407, and a light emission control circuit 407 limits the light emission current of the Xe tube. A coil 408 is a diode for absorbing a flyback voltage generated at both ends of the coil 407 when the light emission control unit 406 interrupts the light emission current. 8 shows a light emission waveform of the Xe tube 404. FIG. 8A shows a light emission waveform when the current limiting coil 407 is provided, and FIG. 8B shows a light emission waveform when the coil is not provided. As shown in the figure, when there is no coil, the light emission current rapidly increases, and the light emission waveform rises. Therefore, when controlling the small light emission amount, even if the light emission is stopped at the time t1, it is actually a circuit. Since the light emission control circuit interrupts the light emission current at time t2 due to the delay of the light emission, the desired light emission amount is exceeded.
On the other hand, when the light emission waveform is gentle as shown in FIG.
Even when light emission is stopped at a predetermined light emission amount, the rate of increase of the light emission amount with respect to the control delay can be suppressed small because the increase in the light emission current is small, so that more preferable controllability can be obtained when controlling the small light emission amount. It is.

Recently, an IGBT has been widely used as a control element used in the above-mentioned light emission control circuit 406, and it has become possible to rapidly cut off the light emission current of the Xe tube. As shown, the emission current of the Xe tube is switched at high speed, so-called FP emission (flat emission)
It is widely practiced to obtain a substantially uniform strobe light referred to as "strobe light".
In the case of a camera having a focal plane shutter, as is well known, in the case of a high-speed shutter at or above the shutter speed at which the shutter curtain fully opens, it is necessary to generate substantially uniform light from the start of travel of the shutter curtain to the end of travel. , This F
By performing P light emission (flat light emission), it is possible to perform flash photography up to a high-speed shutter. FIG. 9 shows an example of a circuit for performing the FP light emission. In FIG. 9, a connection point on the anode side of the diode 408 is connected to a connection point between the Xe tube 404 and the light emission control circuit 406, and a coil is connected. By setting the inductance of 407 large, the rise and fall of the light emission current are smoothed to make the light emission waveform almost uniform.

[0004]

However, in order to make the generated light of the FP emission uniform in the above conventional example, the coil 4
Because it is necessary to give a large inductance to 07,
When strobe light is used as a steep light pulse signal for optical communication, a problem arises in that the rise is too slow. Further, even when the emission of the strobe light is stopped, since the inductance of the coil 407 is large, the emission of light is poor, the controllability is deteriorated, and there is a problem that a steep light pulse cannot be obtained.

It is an object of the invention according to the present application to improve the controllability of the strobe light and to achieve a slow and uniform light emission by obtaining an optimum light emission form according to a required light emission mode when the strobe light is emitted. The purpose is to realize opposing light emitting states.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a switching element connected in series to a flash tube is repeatedly turned on and off to continuously emit light at a substantially constant luminance for a predetermined time. In a strobe device having a flat light emission mode for turning on the switching element and a flash light emission mode for performing flash light emission by turning on the switching element, an inductance value is set as an inductance value in a discharge path for discharging a charge of a flash energy storage capacitor to a flash tube. An inductance means for forming one inductance value and a second inductance value larger than the first inductance value; and causing the inductance means to form the second inductance value in the flat light emission mode, and in the flash light emission mode. Switching to form the first inductance value Freshly provided stage, there is provided a flash device for emitting light at the emission characteristics suitable for each mode.

According to a second aspect of the present invention, there is provided a communication mode in which the switching element is repeatedly turned on and off as a mode of the strobe device. In this mode, the switching means causes the inductance means to form a first inductance value and is suitable for optical communication. A strobe device.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a diagram best illustrating the features of the present invention. In FIG. 1, reference numeral 1 denotes a battery as a power supply, 2 denotes a DC / DC converter, and boosts the battery voltage to several hundred volts. . Reference numeral 3 denotes a main capacitor for charging the output of the DC / DC converter. 4 and 5 are microcomputers (microcomputers) that use the voltage of the main capacitor as a control circuit
Reference numeral 38 denotes a voltage dividing resistor provided for monitoring.
The flash microcomputer 38 has a built-in A / D
The voltage of the main capacitor 3 is controlled to a predetermined voltage by controlling the operation of the DC / DC converter 2 by indirectly monitoring the voltage of the main capacitor 3 by performing A / D conversion by the converter. Reference numeral 6 denotes a first coil which is an inductance as first current limiting means for limiting a light emission current, and 7 denotes a diode for absorbing a flyback voltage generated at both ends of the coil 6 when light emission is stopped.
Reference numeral 8 denotes a second coil which is an inductance as a second current limiting means for limiting a light emission current. In this embodiment, the first coil has a relatively small inductance determined based on the controllability of the flash light emission, and the second coil has the first coil to maintain the uniformity of the FP light emission. On the other hand, a large inductance is set. 9 is a diode for circulating the energy stored in the current limiting coil when light emission is stopped, 10 is a Xe tube as light emitting means, 11
Is a trigger circuit for generating a high voltage of several thousand volts to excite the Xe tube 10 during light emission, and 12 is a light emission control for controlling the light emission current of the Xe tube 10 and controlling the start / stop of light emission of the Xe tube. The circuit is composed of switching elements such as IGBTs. Reference numeral 13 denotes a thyristor as a one-way conductive switching element for short-circuiting both ends of the coil 8 in the forward direction and bypassing a current flowing through the coil 8;
5, 19, 20, 22, and 23 are resistors, 16 and 17 are capacitors, 18 is a PNP transistor, 21 is an NPN transistor, and these two transistors and resistors 14 to 2 are used.
2. A control circuit for controlling the gate of the thyristor 13 with the capacitors 16 and 17 is configured. Reference numeral 30 denotes a data selector, which outputs D0 to D based on signals input to the Y0 and Y1 terminals.
2 is selected and output to the Y terminal. 33 and 35 are X
a light receiving element that is a sensor that receives light from the e-tube 10; 34 and 36 are light receiving circuits that process and amplify signals of the light receiving elements; 37 is an integrating circuit that integrates the output of the light receiving circuit 36;
31 and 32 are comparators. Reference numeral 38 denotes a microcomputer for controlling the entire operation of the strobe, and reference numeral 39 denotes a connection terminal to a camera (not shown), and performs known serial communication using CLK, DI, and DO terminals.

Next, each terminal of the microcomputer 38 will be described.

As described above, CLK, DI, and DO are communication terminals for performing known serial communication with a camera (not shown). CLK receives a synchronous clock signal from the camera, and Synchronously, serial data is transmitted from the camera to the DI terminal, and at the same time, serial data from the strobe is output from the DO terminal. CHG is a terminal for communicating strobe light emission enable information to the camera as current information, and X is an input terminal to which a light emission start signal from the camera is input. INT is a control output terminal for controlling the start and stop of the integration of the integration circuit 36, and the integration is terminated when Lo is Hi and the integration is Hi. DA0 is an output terminal for digital / analog conversion, which converts internal digital data of the microcomputer 38 into a voltage which is an analog signal and outputs a comparator-level voltage for the comparators 31 and 32. AD0 is an input terminal for analog / digital conversion for reading the output voltage of the integration circuit 37 and converting it into digital data for processing inside the microcomputer. Y0 and Y1 are selection signal output terminals for selecting a light receiving element control circuit system according to the light emission mode as described above. TRIG is a terminal for outputting a light emission signal to the trigger circuit 11, FP_SP is a control output terminal for controlling conduction / non-conduction of the thyristor 13 via the control transistors 21 and 18, and AD1 is a high voltage of the main capacitor 3 as described above. Is an analog-digital conversion input terminal for inputting a voltage obtained by dividing the voltage by resistors 4 and 5 and converting the data into digital data to be processed inside the microcomputer 38, and CNT is DC / DC
A control output terminal for controlling the oscillation / stop of the converter 2, and controls the operation of the DC / DC converter 2 according to the voltage of the main capacitor 3 monitored by the above-mentioned AD1 and the operation state of the strobe.

Next, the operation at the time of FP light emission will be described.

During FP light emission, the thyristor 13 is set to a cutoff state in order to make the light emission waveform smooth, and the light emission current is set to flow through both the coil 6 and the coil 8. That is, the FP_SP control terminal of the microcomputer 38 is set to L
Since the transistor 21 and the transistor 18 are turned off, no gate-on signal is applied to the gate of the thyristor 13, and the gate is connected to the cathode via the resistor 15 and the capacitor 17, so that the thyristor 13 is turned off. Remains out of communication.

[0013] Also, according to the FP emission intensity, the microcomputer 3
8 generates a predetermined control voltage at the DA0 terminal,
By outputting Lo and Hi to the Y0 and Y1 terminals, the data selector 30 selects the D2 input. At this time, Xe tube 1
Since 0 is a non-emission state, almost no photocurrent flows to the sensor 33 which directly monitors the Xe tube, no output of the light receiving circuit 31 is generated, and the output of the comparator 31 is Hi.
And the light emission control circuit 12 through the data selector 30.
IGBTs are conducting. At the same time,
By setting the RIG terminal to Hi for a predetermined time, a high voltage is generated from the trigger circuit 11, and the Xe tube 10 starts emitting light. At the same time, the sensor 33 monitoring the Xe tube causes a photocurrent to flow according to the light generated by the Xe tube 10, and when the output voltage of the light receiving circuit 34 becomes higher than the control voltage output to DA0,
The output of the comparator 31 is inverted to the Lo level, the IGBT of the light emission control circuit 12 is cut off, the energy stored in the coil 6 passes through the flyback diode 7, and the energy stored in the coil 8 passes through the diode 9. Although refluxed, the current flowing through the Xe tube gradually decreases. At the same time, the light emission amount also decreases, falls below a predetermined light amount, and when the output of the light receiving circuit 34 falls below the comparator voltage set by DA0, the comparator 31 is inverted again,
The IGBT of the light emission control circuit 12 becomes conductive, and the Xe tube generates more light. Repeat the above process, FP
Light emission is maintained at a substantially constant light emission intensity. The light emission waveform at this time is almost constant including the ripple as shown in FIG. Then, when the predetermined light emission time has elapsed,
The microcomputer 38 sets the Y0 and Y1 terminals to Lo and Lo, forcibly shuts off the IGBT of the light emission control circuit 12, and stops light emission.

Next, the operation at the time of flash light emission will be described.

At the time of flash light emission, the thyristor 13 is set to a conductive state in order to make the light emission waveform steep, and the thyristor 13 is set to a conductive state in order to prevent a light emission current from flowing through the coil 8. That is, the FP_SP control terminal of the microcomputer 38 is set to Hi,
Is turned on, a bias voltage is applied to the gate of the thyristor 13 via the resistor 14, and the thyristor 13 is turned on. In addition, a predetermined control voltage is generated at the DA0 terminal of the microcomputer 38 and Hi and Lo are output to the Y0 and Y1 terminals according to the desired light emission amount, so that the D1 input is selected for the data selector 30. At this time, since the Xe tube 10 has not emitted light, almost no photocurrent flows to the sensor 35 which directly monitors the Xe tube, and since the integration circuit 37 inhibits integration, the output of the comparator 32 is Hi. The IGBT of the light emission control circuit 12 is turned on through the data selector 30. At the same time, by setting the TRIG terminal of the microcomputer 38 to Hi for a predetermined time, a high voltage is generated from the trigger circuit 11 and the Xe tube 1
0 starts light emission. After a predetermined time from the start of light emission, the INT terminal of the microcomputer 38 is set to Lo, and the integration circuit 37 starts integration. The reason why the timing of the trigger generation and the integration is shifted is that the light emission of the Xe tube is slightly delayed from the trigger generation and also that the integration circuit 37 prevents the integration circuit 37 from erroneously integrating noise generated by the trigger. is there. When the light emission integration amount becomes higher than a predetermined control voltage set by AD0, the output of the comparator 32 is inverted to Lo level, the IGBT of the light emission control circuit 12 is cut off, and the energy stored in the coil 6 is The current flowing through the Xe tube is rapidly reduced, and the light emission stops.

Next, with reference to FIG. 2, the difference in the amount of light generated by single flash emission between the conducting state and the non-conducting state of the thyristor 13 will be described.

In FIG. 1, (a) shows the Xe tube 10 when a single flash is emitted with the thyristor 13 turned off.
(B) shows the thyristor 13
Xe tube 1 when single flash light emission is performed while turning on
It shows the generated light of 0. In (a), light emission start t
Light emission stop time t1 due to interruption of light emission control circuit 12 from 0
Until the time t1, the light emission current flows through the coil 6 and the coil 8, so that the rise becomes gentle. After t1, the energy stored in the coil 8 flows through the freewheeling diode 9, so that the light emission stops gently. On the other hand (b)
Since the light emission current flows only through the coil 6 from the light emission start t0 to the light emission stop time t1 due to the interruption of the light emission control circuit 12, the rise is steep, and after t1, the energy stored in the coil 6 is flyback. Since the current flows through the diode 7, almost no current flows through the Xe tube 10, and light emission stops very quickly, although there is afterglow until the ions in the Xe tube 10 disappear.

Next, FIG. 3 illustrates a case where a pulse is repeatedly generated with the light emission waveforms (a) and (b) described in FIG. 2, and (c) illustrates a case where the thyristor 13 is in a cut-off state. , (D) shows the case where the thyristor 13 is in a conductive state. As shown in the figure, in the state (d) in which the thyristor 13 is in the cut-off state, it is possible to generate a high-speed repetitive pulse with respect to the state (c). In this case, the communication speed can be increased. Therefore, as in the case of a wireless strobe or a wireless release device that has been used recently, when communicating the light emission amount, light emission instruction, and the like to other devices such as a slave strobe and a receiver by using light of the Xe tube, high-speed communication is performed. Communication becomes possible. When wireless communication is performed using light from the Xe tube, the FP with the thyristor 13 turned on is set.
Light emission control may be performed. Therefore, three modes of the communication mode, the FP light emission mode, and the flash light emission mode are provided, and the above control can be performed for each mode. Next, with reference to FIG. 4, the difference between the light generated by the FP emission in the conductive state and the non-conductive state of the thyristor 13 will be described.

In FIG. 1, (e) shows the light emitted from the Xe tube 10 when FP emission is performed with the thyristor 13 turned off, and (f) shows the FP with the thyristor 13 turned on. FIG. 4 shows light generated by the Xe tube 10 when light is emitted.

In FIG. 3E, the light emission current flows through the coil 6 and the coil 8, so that the light amount increases moderately when the light emission control circuit 12 is in the conductive state, and the light emission current flows through the coil 8 when the light emission control circuit 12 is in the cut off state. Since the stored energy is effectively used through the freewheeling diode 9, the amount of light is moderately reduced, and the entire FP emission has extremely uniform emission.

On the other hand, in FIG. 3F, the coil 8 is bypassed by the thyristor 13 and the light emission current is limited only through the coil 6. Therefore, when the light emission control circuit 12 is in the conductive state, the generation of the Xe tube 10 is abrupt. When the light increases and the light emission control circuit 12 is in the cutoff state, the light emission of the Xe tube is rapidly stopped as described above, so that the FP light emission has poor uniformity. Also, recently, the high-speed I
Generally, GBT is used, but at the high speed switching as described in FIG.

Therefore, as described in this embodiment, when controllability contradictory to the light emission waveform and light emission controllability is required such as FP light emission and flash light emission, the inductance as the current control means is changed according to the light emission mode. By switching to
Light emission control characteristics optimal for each mode can be obtained.

As described above, in the first embodiment, by switching the inductance for limiting the light emission current depending on the light emission mode, it becomes possible to perform optimal strobe light emission according to the light emission mode. .

(Second Embodiment) FIG. 5 is a circuit diagram of a strobe device according to a second embodiment, in which the same members as those in the first embodiment have the same reference numerals. Description is omitted. In the figure, reference numeral 43 denotes a thyristor for controlling a light emitting current; 44, 45, 49, 50, 52, and 53, resistors,
6, 47 are capacitors, 48 is a PNP transistor, 5
Reference numeral 1 denotes an NPN transistor, which constitutes a control circuit for controlling the gate of the thyristor 43 by the two transistors, the resistors 44 to 52, and the capacitors 46 and 47.

Next, terminals of the microcomputer 38 that are different from those of the first embodiment will be described. The FP terminal is an output terminal that makes the thyristor 43 conductive when emitting FP light, and the SP terminal is an output terminal that makes the thyristor 13 conductive when emitting flash light.

Next, the control operation at the time of FP light emission and flash light emission will be described with reference to FIG.

At the time of FP light emission, the FP terminal of the microcomputer 38 is set to H.
i, the SP terminal is set to Lo, the thyristor 43 is turned on, the thyristor 13 is turned off, and the electric charge accumulated in the main capacitor 3 is transferred to the Xe tube 10 via the thyristor 43 and the coil 8. Flows to At this time, as described in the first embodiment, the coil 8 is set to have an inductance sufficient to gradually increase and decrease the emission current of the FP emission. In this state, by controlling Y0, Y1, and TRIG in the same manner as in the first embodiment, it is possible to perform FP emission having a highly uniform and uniform flat emission waveform.

At the time of flash light emission, the FP terminal of the microcomputer 38 is set to L
o, the SP terminal is set to Hi, the thyristor 13 is turned on, the thyristor 43 is turned off, and the electric charge accumulated in the main capacitor 3 is transferred to the Xe tube 10 via the thyristor 13 and the coil 6. Flows to At this time, as described in the first embodiment, the coil 6 is used to quickly increase or decrease the light emission current of the flash light emission.
The light emission control coil 8 is set to have a small inductance. In this state, by controlling Y0, Y1, and TRIG in the same manner as in the first embodiment, it becomes possible to perform flash light emission having a light emission waveform with a sharp rising and decreasing waveform.

As described above, in the second embodiment, the inductance for limiting the light-emitting current is switched separately according to the light-emitting mode. It is now possible to perform the optimal flash emission according to.

In this embodiment, the thyristor 4
By turning off the thyristor 13 and turning on the thyristor 13 to perform FP light emission control, light emission control in the wireless communication mode can be performed.

(Third Embodiment) FIG. 6 is a circuit diagram of a strobe device according to a third embodiment, which is different from the first embodiment in that a current limiting coil 6 for flash current emission is used. Also, the flyback diode 7 is eliminated. The other parts are the same as in the first embodiment, and a description thereof will be omitted.

In the first embodiment already described,
When the impedance of the Xe tube 10 at the time of light emission is low, the current limiting coil 6 for flash light emission controls the light emission control circuit 12.
Is necessary to limit the upper limit of the control current, and as described above, it is necessary to improve the controllability at the time of low flash light emission, but in the case of a Xe tube whose impedance at the time of light emission is not low, and If the light emission control circuit 12, the light receiving elements 33 and 35, the light receiving circuits 34 and 36, etc. are sufficiently fast, they can be eliminated. However, even in such a case, the current limiting coil 8 is required to maintain the uniformity of the FP light emission.
Therefore, in the third embodiment, the FP_SP terminal of the microcomputer 38 is set to Lo during FP emission, and the thyristor 13
Is turned off, and the current of the main capacitor is
Through which the current is limited, and FP_
By setting the SP terminal to Hi and turning on the thyristor 13 so that no current flows through the coil 8, the emission current gradually rises and falls during FP emission.
It is possible to perform uniform light emission with high uniformity, and to perform light emission having a light emission waveform whose waveform rises sharply and decreases sharply during flash light emission.

As described above, in the third embodiment, the inductance for limiting the light emission current is used only in the FP light emission mode, and is not used in the flash light emission by bypass. As in the first and second embodiments, it is possible to perform optimal strobe light emission according to the light emission mode.

[0034]

As described above, according to the present invention, by selecting the inductance for limiting the light emission current in the light emission mode, it is possible to perform the optimal strobe light emission according to the light emission mode. .

[Brief description of the drawings]

FIG. 1 is an electric circuit block diagram showing an electric configuration of a strobe light according to a first embodiment of the present invention.

FIG. 2 is a light emission waveform chart for explaining a flash light emission waveform in the first embodiment of the present invention.

FIG. 3 is a light emission waveform diagram illustrating a repetitive flash light emission waveform in the first embodiment of the present invention.

FIG. 4 is a light emission waveform diagram for explaining an FP light emission waveform in the first embodiment of the present invention.

FIG. 5 is an electric circuit block diagram showing an electric configuration of a strobe light according to a second embodiment of the present invention.

FIG. 6 is an electric circuit block diagram showing an electric configuration of a strobe light according to a third embodiment of the present invention.

FIG. 7 is an electric circuit block diagram illustrating a strobe circuit in a conventional example.

FIG. 8 is a diagram illustrating a flash light emission waveform of a strobe in a conventional example.

FIG. 9 is a view for explaining an FP emission waveform of a strobe which enables FP emission in a conventional example.

FIG. 10 is an electric circuit block diagram illustrating a flash circuit that enables FP light emission in a conventional example.

[Explanation of symbols]

 3 Condenser 6, 8 Coil 13 Thyristor 14 Xe tube 18, 21 Transistor

Claims (4)

[Claims] A strobe having a flat light emission mode in which switching elements connected in series to a flash tube are repeatedly turned on and off to emit light at a substantially constant luminance for a predetermined time, and a flash light emission mode in which the switching elements are turned on to perform flash light emission. In the device, an inductance for forming a first inductance value and a second inductance value larger than the first inductance value as an inductance value in a discharge path for discharging a charge of the flash energy storage capacitor to the flash tube. And a switching means for causing the inductance means to form the second inductance value in the flat light emission mode and forming the first inductance value in the flash light emission mode. 2. A flash device according to claim 1, wherein said flash device has a communication mode in which said switching element is repeatedly turned on and off, and in said mode, said switching means causes said inductance means to form a first inductance value. 3. The inductance means includes a first coil and a second coil connected in series to the coil and having an inductance value larger than the inductance value of the first coil. Claims: A switching element for short-circuiting a second coil, wherein a first inductance value is formed by turning on the switching element, and a second inductance value is formed by turning off the switching element. Item 7. The strobe device according to Item 1 or 2. 4. The inductance means has a first coil and a second coil having an inductance value larger than the first coil, and the switching means selects the first and second coils and provides the first and second coils in the discharge path. 3. The flash device according to claim 1, further comprising a switching element to be connected.