JP3780038B2 - Strobe device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light emission amount control device in a strobe device.
[0002]
[Prior art]
Conventionally, in a light emitting circuit of a flash light emitting device, in order to improve light emission controllability and to protect the light emission control circuit, an inductor is generally inserted in the light emitting discharge circuit as shown in FIG. Yes. The operation of the figure will be described below. In the figure, 401 is a battery, 402 is a DC / DC converter that converts the voltage of the battery 401 to a high voltage of several hundred volts, 403 is a capacitor that accumulates luminescence energy, and 404 is light emission. The Xe tube 405 is a trigger circuit for generating a high voltage of several thousand volts in order to excite the Xe tube 404 at the time of light emission, and 406 controls the light emission current of the Xe tube 404 to start / stop the light emission of the Xe tube. 407 is a coil for limiting the light emission current of the Xe tube. 408 is a flyback voltage generated at both ends of the coil 407 when the light emission control means 406 cuts off the light emission current. It is a diode for absorption. FIG. 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. As shown in the figure, when there is no coil, the light emission current suddenly increases and the light emission waveform rises. Therefore, even when trying to stop light emission at time t1 when controlling a small amount of light emission, the circuit actually Since the light emission control circuit cuts off the light emission current due to the delay of time, etc., it is delayed at time t2, so that it exceeds the desired amount of light emission.
On the other hand, when the light emission waveform is gentle as shown in FIG. 5B, even when light emission is stopped at a predetermined light emission amount, the increase in the light emission current is slow, so the rate of increase in the light emission amount relative to the control delay can be kept small. Therefore, more preferable controllability can be obtained when the small light emission amount is controlled.
[0003]
Recently, as the control element used in the above-described light emission control circuit 406, IGBTs are often used, and the light emission current of the Xe tube can be cut off rapidly. As shown in FIG. It is widely performed to switch the light emission current of the Xe tube at high speed to obtain a substantially uniform strobe light called so-called FP light emission (flat light emission). In the case of a camera having a focal plane shutter, as is well known, in the case of a high-speed shutter that is higher than the shutter speed at which the shutter curtain is fully opened, it is necessary to generate substantially uniform light from the start of travel of the shutter curtain to the end of travel. By performing this FP 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 this FP light emission. Compared to FIG. 7, the anode-side connection point of the diode 408 is connected to the connection point of the Xe tube 404 and the light emission control circuit 406, and the coil By setting the inductance of 407 large, the light emission waveform is made almost uniform by smoothing the rise and fall of the light emission current.
[0004]
[Problems to be solved by the invention]
However, in order to make the generated light of FP light emission uniform in the conventional example, it is necessary to give a large inductance to the coil 407. Therefore, in order to use strobe light as a steep optical pulse signal for optical communication, it is necessary to The problem arises that is too slow. Further, even when the strobe light emission is stopped, the coil 407 has a large inductance, so that the light emission is not cut off, the controllability is deteriorated, and a steep light pulse cannot be obtained.
[0005]
The object of the invention according to the present application is to improve the controllability of the strobe by obtaining an optimum light emission mode according to the required light emission mode, and to perform light emission that is gentle and uniform light emission. It is to realize the state.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention relates to a flash tube, a condenser for storing flash energy, an output of a sensor that monitors the light emission of the flash tube, and a result of comparison with a predetermined voltage. a flat emission mode to continue the light emission repeatedly turns on and off the switching devices connected in series in the pipe, a flash light emission mode that amount of light emission causes a flashlight to stop the light emission is turned off the switching element reaches a predetermined value in a flash device with, in the discharge path to discharge the charged electric charge of the flash energy storage capacitor against flash tube, a first inductance value and a large second inductance value than the first inductance value as an inductance value an inductance means for forming, in the flat emission mode, said inductance means The second to form the inductance value, when the flash light emission mode, there is provided a flash device provided with switching means for forming said first inductance value to the inductance means.
[0007]
Formation of invention of claim 2, in the strobe device, and a communication mode for turning on and off repeatedly the switching element, the switching means on the occasion to the communication mode, the first inductance value to the inductance means there is provided a flash device Ru is.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 is a diagram that best represents the characteristics of the present invention. In FIG. 1, reference numeral 1 denotes a battery as a power source, and reference numeral 2 denotes a DC / DC converter, which boosts the battery voltage to several hundred volts. 3 is a main capacitor which charges the output of the DC / DC converter. Reference numerals 4 and 5 denote voltage dividing resistors provided to monitor the voltage of the main capacitor by a microcomputer 38 as a control circuit. The stroboscopic microcomputer 38 A / D-converts the divided voltage by a built-in A / D converter, thereby indirectly monitoring the voltage of the main capacitor 3 and controlling the operation of the DC / DC converter 2. The voltage of the main capacitor 3 is controlled to a predetermined voltage. A first coil 6 is an inductance as a first current limiting means for limiting the light emission current, and 7 is 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 the light emission current. In this embodiment, the first coil has a relatively small inductance determined based on the controllability of flash emission, and the second coil is used as the first coil in order to maintain the uniformity of FP emission. In contrast, a large inductance is set. 9 is a diode for circulating the energy accumulated in the current limiting coil when light emission is stopped, 10 is a Xe tube as a light emitting means, and 11 is for generating a high voltage of several thousand volts to excite the Xe tube 10 during light emission. The trigger circuit 12 is a light emission control circuit for controlling the light emission current of the Xe tube 10 and controlling the light emission start / stop of the Xe tube, and is composed of a switching element such as an IGBT. 13 is a thyristor serving as a unidirectional 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, 14, 15, 19, 20, 22, 23 are resistors, Reference numeral 17 denotes a capacitor, 18 denotes a PNP transistor, and 21 denotes an NPN transistor. The two transistors, resistors 14 to 22 and capacitors 16 and 17 constitute a control circuit that controls the gate of the thyristor 13. A data selector 30 selects the inputs D0 to D2 based on the signals input to the Y0 and Y1 terminals and outputs them to the Y terminal. Reference numerals 33 and 35 denote light receiving elements that are sensors that receive light from the Xe tube 10, reference numerals 34 and 36 denote light receiving circuits that process and amplify signals from the light receiving elements, and reference numeral 37 denotes an integrating circuit that integrates the output of the light receiving circuit 36. , 32 are comparators. Reference numeral 38 denotes a microcomputer that controls the operation of the entire flash unit, and 39 denotes a connection terminal with a camera (not shown), which performs known serial communication using CLK, DI, and DO terminals.
[0009]
Next, each terminal of the microcomputer 38 will be described.
[0010]
As described above, CLK, DI, and DO are communication terminals for performing known serial communication with a camera (not shown). A synchronous clock signal from the camera is input to CLK, and in synchronization with the clock signal. 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 ends when the integration is Hi when Lo. DA0 is an output terminal for digital / analog conversion, and is a terminal for converting the internal digital data of the microcomputer 38 into a voltage which is an analog signal and outputting 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 the 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-passage 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. The analog / digital conversion input terminal for inputting the voltage divided by resistors 4 and 5 and converting it into digital data for processing inside the microcomputer 38, CNT is used to oscillate / stop the DC / DC converter 2. This is a control output terminal for controlling, and controls the operation of the DC / DC converter 2 in accordance with the voltage of the main capacitor 3 monitored by the AD1 and the operating state of the strobe.
[0011]
Next, the operation at the time of FP light emission will be described.
[0012]
At the time of FP light emission, the thyristor 13 is set to the cut-off state in order to smooth the light emission waveform, and the light emission current is set to flow through both the coil 6 and the coil 8. That is, since the FP_SP control terminal of the microcomputer 38 is set to Lo and the transistors 21 and 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. Therefore, the thyristor 13 maintains the non-passing state.
[0013]
Further, the data selector 30 selects the D2 input by generating a predetermined control voltage at the DA0 terminal of the microcomputer 38 and outputting Lo and Hi to the Y0 and Y1 terminals according to the FP emission intensity. At this time, since the Xe tube 10 is not emitting light, almost no photocurrent flows through the sensor 33 directly monitoring the Xe tube, no output of the light receiving circuit 31 is generated, and the output of the comparator 31 is Hi. Yes, the IGBT of the light emission control circuit 12 becomes conductive through the data selector 30. At the same time, a high voltage is generated from the trigger circuit 11 by setting the TRIG terminal of the microcomputer 38 to Hi for a predetermined time, and the Xe tube 10 starts to emit light. At the same time, the sensor 33 monitoring the Xe tube causes a photocurrent to flow in accordance with 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 becomes Lo level. The IGBT of the light emission control circuit 12 is cut off, and the energy accumulated in the coil 6 is circulated through the flyback diode 7 and the energy accumulated in the coil 8 is circulated through the diode 9, but the Xe tube The current flowing through decreases gradually. At the same time, when the amount of light emission decreases and becomes equal to or less than the predetermined light amount and the output of the light receiving circuit 34 becomes equal to or less than the comparator voltage set by DA0, the comparator 31 is inverted again, and the IGBT of the light emission control circuit 12 becomes conductive, and Xe The tube generates more light. By repeating the above process, the FP light emission is maintained at a substantially constant light emission intensity. The light emission waveform at this time is substantially constant including ripples as shown in FIG. When a predetermined light emission time elapses, the microcomputer 38 sets Y0, Y1 terminals = Lo, Lo, the IGBT of the light emission control circuit 12 is forcibly cut off, and light emission stops.
[0014]
Next, the operation during flash emission will be described.
[0015]
At the time of flash emission, the thyristor 13 is set to a conductive state in order to make the 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, by setting the FP_SP control terminal of the microcomputer 38 to Hi and turning on the transistor 21 transistor 18, a bias voltage is applied to the gate of the thyristor 13 through the resistor 14, and the thyristor 13 is turned on. Further, the data selector 30 selects the D1 input by generating a predetermined control voltage at the DA0 terminal of the microcomputer 38 and outputting Hi and Lo to the Y0 and Y1 terminals according to the desired light emission amount. At this time, since the Xe tube 10 is not emitting light, almost no photocurrent flows through the sensor 35 that directly monitors the Xe tube, and the integration circuit 37 inhibits integration, so that the output of the comparator 32 is Hi. Then, the IGBT of the light emission control circuit 12 becomes conductive 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 10 starts to emit light. 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. Note that the trigger generation and integration timings are shifted in order to prevent the integration circuit 37 from erroneously integrating the noise generated by the trigger in addition to the fact that the light emission of the Xe tube is somewhat delayed from the trigger generation. is there. When the light emission integral amount becomes higher than the predetermined control voltage set by AD0, the output of the comparator 32 is inverted to the Lo level, the IGBT of the light emission control circuit 12 is cut off, and the energy accumulated in the coil 6 is the flyback diode 7. The current flowing through the Xe tube rapidly decreases and light emission stops.
[0016]
Next, with reference to FIG. 2, the difference in the amount of light generated by single flash emission between the thyristor 13 in a conducting state and a non-passing state will be described.
[0017]
In this figure, (a) shows the light generated by the Xe tube 10 when single flash emission is performed with the thyristor 13 turned off, and (b) shows a single shot with the thyristor 13 turned on. The light generated by the Xe tube 10 when flashing is performed is shown. In (a), since the light emission current flows through the coils 6 and 8 from the light emission start t0 to the light emission stop time t1 due to the light emission control circuit 12 being cut off, the rise is slow, and after t1, the energy accumulated in the coil 8 is increased. Since it flows through the freewheeling diode 9, the light emission stops slowly. On the other hand, in (b), since the light emission current flows through only 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 is accumulated in the coil 6. Since energy flows through the flyback diode 7, almost no current flows in the Xe tube 10, and although there is afterglow until ions in the Xe tube 10 disappear, light emission stops very rapidly.
[0018]
Next, FIG. 3 illustrates a case where a repetitive pulse is generated with the light emission waveforms of (a) and (b) described in FIG. 2, (c) is a case where the thyristor 13 is in a shut-off state, and (d ) Is a case where the thyristor 13 is in a conductive state. As shown in the figure, in (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 (c), and information is communicated by causing the Xe tube to flash at high speed. In this case, the communication speed can be increased. Therefore, when communicating the amount of light emission, light emission instruction, etc. to other slave strobes and receivers using the light of the Xe tube like the wireless strobes and wireless release devices used nowadays, it is fast. Communication is possible. When wireless communication is performed using light from the Xe tube, FP light emission control may be performed with the thyristor 13 turned on. 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 in the light generated by the FP emission between the conduction state and the non-passage state of the thyristor 13 will be described.
[0019]
In the figure, (e) shows the light generated by the Xe tube 10 when FP light emission is performed with the thyristor 13 turned off, and (f) performs FP light emission with the thyristor 13 turned on. The light generated by the Xe tube 10 in the case of the above is shown.
[0020]
In FIG. (E), since the light emission current flows through the coil 6 and the coil 8, the increase in the amount of light is moderate when the light emission control circuit 12 is in the conductive state, and the light emission control circuit 12 is accumulated in the coil 8 when the light emission control circuit 12 is in the cutoff state. Since energy is effectively utilized through the freewheeling diode 9, the amount of light is gradually reduced, and the entire FP emission is extremely uniform.
[0021]
On the other hand, in FIG. 8 (f), 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 conductive, the light generated by the Xe tube 10 increases rapidly. In addition, when the light emission control circuit 12 is in the cut-off state, the light emission of the Xe tube is suddenly stopped as described above, so that the FP light emission has poor uniformity. In addition, a high-speed IGBT is generally used for the light emission control circuit 12 in recent years. However, there is a risk that the element is destroyed by high-speed switching as described in (f).
[0022]
Therefore, as described in this embodiment, when controllability opposite to the light emission waveform and light emission controllability is required, such as FP light emission and flash light emission, the inductance which is the current control means is switched according to the light emission mode. As a result, it is possible to obtain light emission control characteristics that are optimal for each mode.
[0023]
As described above, in the first embodiment, the optimum strobe light emission according to the light emission mode can be performed by switching the inductance for limiting the light emission current according to the light emission mode.
[0024]
(Second Embodiment)
FIG. 5 is a circuit diagram of a strobe device representing the second embodiment, and the same members as those in the first embodiment are given the same reference numerals. Description is omitted. In the figure, 43 is a thyristor for controlling the light emission current, 44, 45, 49, 50, 52 and 53 are resistors, 46 and 47 are capacitors, 48 is a PNP transistor, 51 is an NPN transistor, The resistors 44 to 52 and the capacitors 46 and 47 constitute a control circuit for controlling the gate of the thyristor 43.
[0025]
Next, terminals of the microcomputer 38 different from those of the first embodiment will be described. The FP terminal is an output terminal that makes the thyristor 43 conductive when FP light is emitted, and the SP terminal is an output terminal that makes the thyristor 13 conductive when flashing.
[0026]
Next, the control operation at the time of FP light emission and flash light emission will be described with respect to parts different from the first embodiment.
[0027]
During FP light emission, the FP terminal of the microcomputer 38 is set to Hi and the SP terminal is set to Lo, whereby the thyristor 43 is turned on, the thyristor 13 is turned off, and the charge accumulated in the main capacitor 3 is 43, flows through the coil 8 to the Xe tube 10. At this time, as described in the first embodiment, the coil 8 is set to have an inductance sufficient to gently increase or decrease the light emission current of FP light emission. In this state, similarly to the first embodiment, by controlling Y0, Y1, and TRIG, it is possible to perform FP light emission having a uniform and uniform flat light emission waveform.
[0028]
During flashing, by setting the FP terminal of the microcomputer 38 to Lo and setting the SP terminal to Hi, the thyristor 13 is turned on, the thyristor 43 is turned off, and the charge accumulated in the main capacitor 3 is 13, flows through the coil 6 to the Xe tube 10. At this time, as described in the first embodiment, the coil 6 has a small inductance with respect to the FP light emission control coil 8 in order to quickly increase and decrease the light emission current of the flash light emission. It is set. In this state, similarly to the first embodiment, by controlling Y0, Y1, and TRIG, it is possible to perform flash emission having a light emission waveform with sharp rising and decreasing waveforms.
[0029]
As described above, in the second embodiment, since the inductance for limiting the light emission current is separated and switched according to the light emission mode, it corresponds to the light emission mode as in the first embodiment. It has become possible to perform optimal strobe light emission.
[0030]
Even in this embodiment, if the thyristor 43 is turned off and the thyristor 13 is turned on to perform the FP light emission control, the light emission control in the wireless communication mode can be performed.
[0031]
(Third embodiment)
FIG. 6 is a circuit diagram of a strobe device representing the third embodiment. In contrast to the first embodiment, the current limiting coil 6 and the flyback diode 7 during flash emission are eliminated. Since other parts are the same as those of the first embodiment, description thereof will be omitted.
[0032]
In the first embodiment already described, the current limiting coil 6 for flash emission is used to limit the upper limit of the control current of the light emission control circuit 12 when the impedance of the Xe tube 10 is low. As described above, it is necessary for improving the controllability at the time of low flash emission, but in the case of an Xe tube whose impedance at the time of light emission is not low, and the light emission control circuit 12 and the light receiving element 33. , 35 and the light receiving circuits 34, 36, etc. can be abolished. However, even in that case, the current limiting coil 8 is necessary to maintain the uniformity of the FP emission. Therefore, in the third embodiment, when the FP light is emitted, the FP_SP terminal of the microcomputer 38 is set to Lo, the thyristor 13 is turned off, and the current of the main capacitor is limited to the current through the coil 8, and the flash light is emitted. By setting the FP_SP terminal to Hi and making the thyristor 13 conductive so that no current flows through the coil 8, the light emission current rises and falls slowly and with uniform uniformity and uniform light emission during FP light emission. It is possible to perform light emission having a light emission waveform with a sharp rising and decreasing waveform during flash emission.
[0033]
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 by being bypassed in the flash light emission. Similar to the second embodiment, it is possible to perform optimum strobe light emission according to the light emission mode.
[0034]
【The invention's effect】
As described above, in the present invention, the optimum strobe light emission according to the light emission mode can be performed by selecting the inductance for limiting the light emission current according to the light emission mode.
[Brief description of the drawings]
FIG. 1 is an electric circuit block diagram showing an electrical configuration of a strobe according to a first embodiment of this invention.
FIG. 2 is a light emission waveform diagram for explaining a flash light emission waveform in the first embodiment of the present invention.
FIG. 3 is a light emission waveform diagram for explaining 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 electrical configuration of a strobe according to a second embodiment of this invention.
FIG. 6 is an electric circuit block diagram showing an electrical configuration of a strobe according to a third embodiment of the present invention.
FIG. 7 is an electric circuit block diagram for explaining a strobe circuit in a conventional example.
FIG. 8 is a diagram for explaining a flash light emission waveform of a strobe in a conventional example.
FIG. 9 is a diagram for explaining a FP light emission waveform of a strobe that enables FP light emission in a conventional example.
FIG. 10 is an electric circuit block diagram illustrating a strobe circuit that enables FP light emission in a conventional example.
[Explanation of symbols]
3 Capacitor 6, 8 Coil 13 Thyristor 14 Xe tube 18, 21 Transistor

Claims (4)

A flash tube, a capacitor for storing flash energy, and a switching element connected in series to the flash tube are repeatedly turned on and off according to a comparison result between the output of the sensor that monitors the light emission of the flash tube and a predetermined voltage. In a strobe device having a flat light emission mode for continuing light emission and a flash light emission mode for performing flash light emission for turning off the switching element and stopping light emission when the light emission amount reaches a predetermined value ,
A discharge path for discharging the charges of the flash energy storage capacitor against flash tube, inductance means for forming a first inductance value as an inductance value, a large second inductance value than the first inductance value When,
In the flat emission mode, the inductance means to form the second inductance value, when the flash light emission mode, strobe, characterized in that a switching means for forming said first inductance value to the inductance means apparatus. And a communication mode for turning on and off repeatedly the switching element, the switching means on the occasion to the communication mode, according to claim 1, characterized in that Ru to form the first inductance value to the inductance means Strobe device. Said inductance means includes a first coil having a second coil of larger inductance value than the inductance value of said first coil while being connected in series with said first coil, said switching means said first a switching element for short-circuiting the second coil, the switching element to form a said first inductance value by turning on the, to form the second inductance value by turning off the switching element according Item 3. The strobe device according to item 1 or 2. Said inductance means includes a first coil having a second coil of larger inductance value than the first coil, the switching means selects one of said first coil and the second coil flash device according to claim 1 or 2, characterized in that it comprises a switching element connected in the discharge path Te.

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