JP2008064850A - Stroboscopic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate trigger voltage high enough to emit strobe light. <P>SOLUTION: A power supply part for trigger 15 comprising a diode for preventing back flow 15a and a power supply capacitor for trigger 15b which are connected in series is connected to a main capacitor 12 in parallel. A trigger capacitor 27 is connected to the power supply capacitor for trigger 15b in parallel, and is charged with the inter-terminal voltage of the power supply capacitor for trigger 15b. A discharge suppressing resistance 16 suppresses the discharge of the power supply capacitor for trigger 15b when an IGBT 17a is turned on in order to discharge the trigger capacitor 27. After discharging for the strobe light emission, the trigger capacitor 27 is charged to attain charging voltage necessary for the strobe light emission by the power supply capacitor for trigger 15b which is already charged. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a strobe device.

  A strobe device that emits strobe light toward a subject in synchronization with shooting is known. The strobe device includes a main capacitor that is charged to a high voltage by a power source such as a booster circuit, a strobe discharge tube (Xe tube) that emits strobe light by discharging the charge accumulated in the main capacitor, and a strobe when emitting strobe light. It comprises a trigger circuit for applying a trigger voltage to the discharge tube.

  As shown in FIG. 8 as an example of a strobe device, a main circuit 51, a series circuit of a resistor 52 and a trigger capacitor 53 are connected in parallel to a power supply unit 50 such as a booster circuit. 53 are each charged to the specified charging voltage by the output voltage of the power supply unit 50. When the switch 54 is turned on, the trigger capacitor 52 is discharged, the discharge current flows to the primary side of the trigger transformer 55, and a trigger voltage of several KV, for example, generated on the secondary side is generated.

  When the trigger voltage is applied to the strobe discharge tube 56, the electric charge accumulated in the main capacitor 51 is discharged in the strobe discharge tube 56, and strobe light emission is started. Then, by turning off the switch 54, the connection between the main capacitor 51 and the strobe discharge tube 56 is cut off, and the strobe light emission ends. The resistor 53 prevents the main capacitor 51 from discharging without passing through the path of the strobe discharge tube 56 when the switch 54 is turned on.

  Also, photographic devices such as digital cameras are known for continuous shooting functions that continuously shoot within a short period of time, and stroboscope devices that emit flash continuously in synchronization with each shooting during the continuous shooting are also known. Yes. When performing strobe light emission continuously, the amount of charge that can be charged during light emission pause is small compared to the amount of discharge due to strobe light emission even if the main capacitor is continuously charged during the continuous light emission. The charging voltage decreases with each light emission.

  When the charging voltage of the main capacitor falls below a predetermined minimum emission voltage, strobe light cannot be emitted, and the number of continuous shots for continuous shooting is limited. In order to relax the restriction on the number of continuous shots, for example, in Patent Document 1, the strobe emission amount is reduced by setting the gain of the photographing circuit system to be higher than normal, thereby reducing the main capacitor that decreases with each emission. The charging voltage is reduced.

In addition, with a plurality of main capacitors that are alternatively charged, when one main capacitor is charged, strobe light emission is performed with the main capacitor in a state where no other charging is required, There is also known a strobe device that can continuously emit strobe light at short time intervals (see Patent Document 2).
JP-A-5-167910 JP 2006-72048 A

  By the way, in order to perform strobe light emission, it is necessary not only to charge the main capacitor above the minimum light emission voltage, but also to apply a trigger voltage to the strobe discharge tube so that the main capacitor starts discharging in the strobe discharge tube. There is a need to generate a sufficiently high trigger voltage for stable light emission. Since the trigger voltage depends on the charging voltage of the trigger capacitor, it is necessary to sufficiently increase the charging voltage of the trigger capacitor at the stage of starting light emission. However, in the configuration in which the main capacitor and the trigger capacitor are connected in parallel as shown in FIG. 8, the charging voltage of the trigger capacitor is the same as the charging voltage of the main capacitor, and the capacitance of the main capacitor is large. Therefore, the charging voltage of the trigger capacitor cannot be sufficiently increased in a short time. For this reason, particularly when performing strobe light emission continuously as described above, there is a problem that the strobe light emission cannot be performed due to insufficient trigger voltage, and the number of light emission times is thereby limited.

  The present invention has been made to solve the above-described problem. Even when the charging voltage of the main capacitor is lowered, the trigger capacitor has a sufficiently high charging voltage so that the trigger capacitor is sufficiently charged to emit strobe light. An object of the present invention is to provide a strobe device capable of generating a voltage.

  In order to achieve the above object, the strobe device according to claim 1 includes a trigger power supply capacitor charged by the power supply unit and a backflow prevention means for preventing current from flowing from the trigger power supply capacitor to the main capacitor. A trigger power source connected in parallel with the main capacitor, and a trigger capacitor connected in parallel with the trigger power capacitor and charged by the voltage across the terminals of the trigger power capacitor. A trigger voltage generator that generates a trigger voltage, and a discharge suppression unit that suppresses the trigger power capacitor from being discharged when the trigger capacitor is discharged, and allows the trigger capacitor to be charged by the trigger power capacitor immediately after the trigger capacitor is discharged. It is provided.

  In the strobe device according to claim 2, the backflow prevention means is a backflow prevention diode, and the trigger power supply is connected to the power supply in parallel with the main capacitor as a series circuit of the backflow prevention diode and the trigger power supply capacitor. It is a thing.

  In the strobe device according to claim 3, the power supply unit is connected in parallel with the first diode that rectifies the high-voltage alternating current and supplies power to the main capacitor in the same direction as the first diode, and rectifies the high-voltage alternating current. Thus, power is supplied to the trigger power supply unit, and a second diode is provided as a backflow prevention means. According to a fourth aspect of the present invention, a damping resistor is provided between the second diode and the trigger power supply capacitor to suppress overshoot of the voltage output from the second diode.

  The strobe device according to claim 5 includes a charge control unit that detects the voltage between terminals of the main capacitor and controls the operation of the power supply unit so that the voltage between the terminals maintains a predetermined specified charging voltage. .

  According to a sixth aspect of the present invention, there is provided a strobe device including a first circuit for preventing backflow and a main capacitor, a trigger power source including a second backflow preventing diode as backflow preventing means, and an output voltage of the power source. A smoothing capacitor for smoothing is connected to the power supply unit in parallel.

  According to a seventh aspect of the present invention, the strobe device includes a charge control unit that controls the operation of the power source unit so that the main capacitor holds a predetermined specified charging voltage based on the voltage across the terminals of the smoothing capacitor.

  The strobe device according to claim 8 is provided separately from the trigger switching means for opening and closing the trigger discharge circuit of the trigger capacitor when the trigger voltage is generated, and the trigger switching means. The light emission control switching means for opening and closing the light emission discharge circuit when discharging through the discharge tube, and the strobe light emission, the trigger discharge circuit and the light emission discharge circuit were closed to start the strobe light emission. Immediately after that, the trigger discharge circuit is opened, and the trigger switching means and the switch control means for controlling the light emission control switching means so as to close the light emission discharge circuit at the timing of stopping the strobe light emission thereafter. is there.

  According to the present invention, the trigger power supply unit having the trigger power supply capacitor and the backflow prevention means for preventing current from flowing from the trigger power supply capacitor to the main capacitor is connected in parallel with the main capacitor, Since the trigger capacitor is charged with the voltage between the terminals of the trigger power supply capacitor, even if the charge voltage of the main capacitor drops, the trigger capacitor is charged to a sufficiently high charge voltage with the trigger power supply capacitor, and the strobe light is emitted. It is possible to generate a trigger voltage necessary for the operation.

  A circuit of the strobe device according to the first embodiment of the present invention is shown in FIG. This strobe device is mounted on, for example, a digital camera having a continuous shooting function that continuously shoots at short intervals, and is capable of emitting a strobe for each shooting when performing continuous shooting. The strobe light emission for each photographing is a pre-light emission for preventing red eyes and a subsequent main light emission for actual photographing.

  The strobe device is roughly divided into a charge control unit 10, a power supply unit 11, a main capacitor 12, a strobe discharge tube 13, a trigger voltage generation unit 14, a trigger power supply unit 15, a discharge suppression resistor 16, a light emission control unit 17, and the like. The

  The power supply unit 11 includes a battery 21, a step-up transformer 22, an IGBT 23, and a rectifying diode 24. A battery 21 is connected to the primary coil 22 a of the step-up transformer 22 via the IGBT 23. The IGBT 23 is repeatedly turned on / off by the charge control unit 10 when charging the main capacitor 12 and the like. By turning on / off the IGBT 23, the primary current flowing from the battery 21 to the primary coil 22a is intermittently generated, and the secondary coil 22b generates a high voltage, for example, 300V alternating current according to the winding ratio with the primary coil 22a.

  The secondary coil 22b has one end connected to the anode of the rectifying diode 24 and the other end grounded. The rectifying diode 24 half-wave rectifies and outputs the output voltage of the step-up transformer 22, that is, the output voltage of the secondary coil 22b.

  The configuration of the power supply unit 11 is merely an example, and is not limited thereto. For example, the configuration may be such that full-wave rectification is performed and an output voltage is output, or a high-voltage DC is output. .

  The main capacitor 12 has one end connected to the cathode of the rectifying diode 24 and the other end grounded, and is charged to a high voltage by the power supply unit 11. As the main capacitor 12, a capacitor having a large capacitance is used so that the charging voltage can be maintained at the minimum light emission possible voltage V1 or higher at which the strobe light can be emitted even if the light is continuously emitted a plurality of times. In this example, about 100 μF is used.

  The strobe discharge tube 13 has one of a pair of discharge electrodes connected to one end of the main capacitor 12, and the other connected to the collector terminal of the IGBT 17a of the light emission control unit 17, and the emitter terminal of the IGBT 17a is grounded. Thereby, the charging voltage of the main capacitor 12 is applied between the pair of discharge electrodes while the IGBT 17a is on.

  The strobe discharge tube 13 is provided with a trigger electrode 13a for applying a trigger voltage to the outer periphery of the tube wall. As is well known, when a trigger voltage of a certain level or higher is applied from the trigger electrode 13a to the strobe discharge tube 13, the Xe gas enclosed therein is ionized to break insulation, and is stored in the main capacitor 12 between the pair of discharge electrodes. If the generated charge can be discharged and the main capacitor 12 is charged to the minimum light emission possible voltage V1 or more, discharge, that is, strobe light emission is started. In the following, the lowest trigger voltage at which strobe light emission can be started is referred to as the lowest trigger voltage.

  The trigger power supply unit 15 is provided to stably generate a trigger voltage equal to or higher than the minimum trigger voltage for each strobe light emission, and includes a backflow prevention diode 15a and a trigger power supply capacitor 15b. The backflow preventing diode 15a has an anode connected to the cathode of the rectifying diode 24, a cathode connected to one end of the trigger power supply capacitor 15b, and the other end of the trigger power supply capacitor 15b grounded. That is, a trigger power supply unit 15 formed of a series circuit of a backflow prevention diode 15 a and a trigger power supply capacitor 15 b is connected in parallel with the main capacitor 12.

  The trigger power supply capacitor 15b is charged by feeding the output of the power supply unit 11 through the backflow prevention diode 15a. The backflow prevention diode 15a serves as a backflow prevention means for preventing the charged trigger power supply capacitor 15b and a trigger capacitor 27 described later from discharging so as to flow current toward the main capacitor 12. In response to the decrease in the charging voltage of the main capacitor 12, the charging voltage of the capacitors 15b and 27 is prevented from decreasing.

  Strictly speaking, the trigger power capacitor 15b is affected by the voltage drop of the backflow prevention diode 15a. However, when the charging voltage (inter-terminal voltage) is equal to or lower than the charging voltage of the main capacitor 12, the trigger power capacitor 15b It is charged by operation and the charging voltage rises. On the other hand, when the charging voltage of the main capacitor 12 is lower than the charging voltage of the trigger power supply capacitor 15b, the main capacitor 12 is charged by the power supply unit 11, but the trigger power supply capacitor 15b is connected via the backflow prevention diode 15a. The battery is not charged.

  The trigger voltage generator 14 includes a trigger capacitor 27 and a trigger transformer 28. The trigger transformer 28 includes a primary coil 28a and a secondary coil 28b that are inductively coupled to each other. The trigger capacitor 27 has one end connected to the primary coil 28a and the other end grounded. The other end of the primary coil 28a is connected to a connection point between the backflow prevention diode 15a and the trigger power supply capacitor 15b via the discharge suppression resistor 16. That is, the trigger capacitor 27 is connected in series with the primary coil 28a and the discharge suppression resistor 16, but is connected in parallel with the trigger power supply capacitor 15b. By charging the trigger capacitor 27 with the voltage between the terminals of the trigger power supply capacitor 15b in this way, even when the charging voltage of the main capacitor 12 is lower than the trigger capacitor 27, the trigger capacitor 27 is charged, and at least The minimum trigger charging voltage V2 that can generate the minimum trigger voltage is set to be equal to or higher.

  When charging the trigger capacitor 27 with the voltage between the terminals of the trigger power supply capacitor 15b, the charge voltage of the trigger power supply capacitor 15b decreases until the charge voltages of the capacitors 15b and the trigger capacitor 27 become the same. Therefore, in order to increase the charging voltage of the trigger capacitor 27, it is preferable that the capacitance of the trigger power supply capacitor 15b is sufficiently larger than that of the trigger capacitor 27. In this example, the trigger capacitor 27 is 0.047 μF, and the trigger power supply capacitor 15 b is 0.47 μF.

  The end of the primary coil 28a on the side of the discharge suppression resistor 16 is connected to the collector terminal of the IGBT 17a, and when the IGBT 17a is turned on, the trigger capacitor 27 is discharged by passing a discharge current through the primary coil 32a. It is.

  The secondary coil 28b has one end connected to the trigger electrode 13a and the other end connected to the discharge electrode on the IGBT 17a side of the strobe discharge tube 13 through a connection point between the primary coil 28a and the discharge suppression resistor 16. . As a result, the trigger voltage generated in the secondary coil 28b when the discharge current of the trigger capacitor 27 flows through the primary coil 28a is applied to the strobe discharge tube 13 via the trigger electrode 13a.

  The discharge suppression resistor 16 suppresses the trigger power supply capacitor 15b from discharging when the trigger capacitor 27 is discharged in order to generate the trigger voltage, while the trigger capacitor 27 uses the voltage between the terminals of the trigger power supply capacitor 15b. It is a discharge suppression means that allows charging. The discharge suppression resistor 16 increases the effect of suppressing discharge as the resistance value is increased in order to reduce the discharge amount of the trigger power supply capacitor 15b when the IGBT 17a is turned on. However, since the speed of charging decreases, it is determined appropriately in consideration of them. In this example, the discharge suppression resistor 16 is 1 MΩ.

  In this strobe device, a series circuit of the discharge suppression resistor 16, the primary coil 28a, and the trigger capacitor 27 is connected in parallel to the trigger power supply capacitor 15b, but a series circuit of the discharge suppression resistor 33 and the trigger capacitor 31 is provided. The trigger power supply capacitor 15b may be connected in parallel. Further, as the discharge suppression means, for example, switching means that is turned on / off in contradiction to the IGBT 17a can be used.

  The light emission control part 17 is comprised from IGBT17a and the switch control circuit 17b which controls ON / OFF of this IGBT17a. In the IGBT 17a, the collector terminal is connected to the strobe discharge tube 13 and the primary coil 28a as described above, and the emitter terminal is grounded. The IGBT 17a is turned on / off by the gate-emitter voltage from the light emission controller 17b. .

  The IGBT 17a includes a discharge circuit for light emission when the main capacitor 12 discharges through the strobe discharge tube 13 for strobe light emission, and a discharge circuit when the trigger capacitor 27 discharges through the primary coil 28a to generate a trigger voltage. It is provided in a common part with the trigger discharge circuit, and these discharge circuits are opened and closed simultaneously by turning them on / off. The switch light emission control circuit 17b turns on the IGBT 17a at the timing of applying the trigger voltage, and turns it off when the strobe light emission is finished thereafter. In this example, an IGBT is used to open and close each discharge circuit. However, the present invention is not limited to this, and other switching means can be used.

  Various timings for turning off the IGBT 17a by the switch light emission control circuit 17b can be employed depending on the use of the strobe light emission, the light control method, and the like. In this example, the IGBT 17b is turned off after a certain period of time has elapsed since the pre-light emission for preventing red-eye, and the reflected light from the subject is received by the sensor in the actual light emission for actually photographing the subject, Control is performed to turn off when the strobe irradiation amount obtained based on the light reception result reaches a predetermined level.

  The charging control unit 10 detects the potential on the cathode side of the rectifying diode 24, that is, the charging voltage of the main capacitor 12, and controls the operation of the power supply unit 11 based on the detected potential. For example, when the digital camera is in the shooting mode, the charging control unit 10 stops the booster circuit 11 when the charging voltage of the main capacitor 12 reaches a specified charging voltage of, for example, 300 V, and the charging voltage starts to be charged. By controlling so that charging is resumed when the voltage drops to the voltage, the charging voltage of the main capacitor 12 is maintained substantially at the specified charging voltage. Further, when performing continuous shooting and performing strobe light emission, the power supply unit 11 is continuously operated to perform charging regardless of the charging voltage of the main capacitor 12. Note that the charging control is not limited to this.

  Next, the operation of the above configuration will be described with reference to FIG. 2, taking as an example the case of continuous shooting while performing strobe light emission. In the following, it is assumed that the capacitors 12, 15b, 31 are not charged as an initial state.

  When the power of the digital camera is turned on and the shooting mode is selected, the power supply unit 11 is activated by the charge control unit 10. When the power supply unit 11 is operated, an alternating high voltage generated by the step-up transformer 22 is rectified and output by the rectifier diode 24 and supplied to the main capacitor 12 to charge the main capacitor 12, and its charging voltage Rises.

  Further, the output from the rectifying diode 24 is also supplied to the trigger power supply capacitor 15b via the backflow prevention diode 15a, the trigger power supply capacitor 15b is charged, and the charging voltage is increased. In this way, when the charging voltage of the trigger power supply capacitor 15b rises, the charging voltage is applied to the trigger capacitor 27 via the discharge suppression resistor 16 and the primary coil 28a, whereby the trigger capacitor 27 is charged. The charging voltage increases.

  When the charging control unit 10 detects that the charging voltage of the main capacitor 12 has reached the specified charging voltage based on the potential of the cathode of the rectifying diode 24, the power supply unit 11 is stopped. After the charging is stopped, when the charging voltage of the main capacitor 12 is lowered to the charging start voltage due to natural discharge or the like, the power supply unit 11 is operated again and charged to the specified charging voltage. Thereafter, the stop and operation of the power supply unit 11 are repeated in the same manner, so that the charging voltage of each capacitor 12, 15b, 31 is kept substantially at the specified charging voltage.

  When continuous shooting is instructed, pre-flash for the first shooting is performed. Moreover, the power supply part 11 is operated continuously. The IGBT 17a is turned on by the switch control circuit 17b, and the charged trigger capacitor 27 passes a discharge current to the trigger discharge circuit on the path returning to the trigger capacitor 27 via the primary coil 28a and the IGBT 17a. As a result, a trigger voltage is generated in the secondary coil 28b.

  Since the trigger capacitor 27 is charged to a specified charging voltage equal to or higher than the minimum trigger charging voltage V2, a trigger voltage equal to or higher than the minimum trigger voltage necessary to start the strobe emission is applied to the strobe discharge tube 13 via the trigger electrode 13a. Applied. On the other hand, when the IGBT 17a is turned on, the charging voltage of the main capacitor 12 charged to the minimum light emission possible voltage V1 or more is applied to the strobe discharge tube 13, so that the strobe discharge is caused by the application of the trigger voltage. The main capacitor 12 is discharged between the discharge electrodes of the tube 13, and strobe light emission is started.

  The IGBT 17a is turned off when a certain time has elapsed since it was turned on. As a result, the connection between the strobe discharge tube 13 and the main capacitor 12 is cut off, so that the strobe light emission stops. This completes the pre-flash in the first shooting.

  By performing the pre-light emission as described above, the trigger capacitor 27 is discharged and its charging voltage becomes “0”, but the trigger power supply capacitor 15b is discharged while the IGBT 17b is on, Since the discharge amount is reduced by the suppression resistor 16, the decrease in the charging voltage is small. Further, the charging voltage of the main capacitor 12 is lowered by the amount discharged by the strobe discharge tube 13.

  For example, if the charging voltage of the main capacitor 12 is lower than the charging voltage of the trigger power supply capacitor 15b when the IGBT 17a turns from OFF to ON, the main capacitor 12 is charged by the power supply from the power supply unit 11, and the charging voltage increases. However, the trigger power supply capacitor 15b is not charged. If the difference between the main capacitor 12 and the trigger power supply capacitor 15b is small, the charging voltage of the main capacitor 12 reaches the charging voltage of the trigger power supply capacitor 15b while the IGBT 17b is turned off. Power is supplied to 15b, and the charging voltage of each capacitor 12, 15b increases.

  On the other hand, when the IGBT 17b is turned off, the trigger capacitor 27 is charged by the trigger power capacitor 15b because the voltage between the terminals of the trigger power capacitor 15b, that is, the charging voltage is applied via the discharge suppression resistor 16 and the primary coil 28a. . By this charging, the charging voltage of the trigger capacitor 27 is increased, and the charging voltage of the trigger power supply capacitor 15b is decreased. However, since the capacitance of the trigger power supply capacitor 15b is increased, the decrease in the charge decrease is small, so that the charge voltage of the trigger capacitor 27 can be set to the minimum trigger charge voltage V2. If the charging voltage of the trigger power capacitor 15b and the main capacitor 12 are substantially the same as described above, the charging voltage is increased by charging by the power supply unit 11, and the charging voltage of the trigger capacitor 27 is increased accordingly. .

  When an appropriate time elapses from the first pre-flash, the IGBT 17a is turned on in synchronization with the first shooting and the main flash is performed. As in the pre-light emission, when the IGBT 17 a is turned on, the trigger voltage is applied to the strobe discharge tube 13 by the discharge of the trigger capacitor 27 and the charging voltage of the main capacitor 12 is applied to the strobe discharge tube 13. .

  Since the trigger capacitor 27 is equal to or higher than the minimum trigger charging voltage V2, a trigger voltage equal to or higher than the minimum trigger voltage is applied to the strobe discharge tube 13, and the main capacitor 12 is equal to or higher than the minimum light emission possible voltage V1. The flash fires. When the necessary strobe light emission amount is obtained, the IGBT 17b is turned off and the strobe light emission is stopped.

  When the IGBT 17b is turned off, the capacitors 12, 15b, and 27 are charged in the same manner as after the pre-light emission. When the amount of strobe light is relatively large as in the case of main light emission, for example, the charging voltage of the main capacitor 12 There is a case where the charging voltage of the main capacitor 12 does not reach the charging voltage of the trigger power supply capacitor 15b while the IGBT 17b is turned off, that is, until the next pre-light emission.

  In such a case, the trigger capacitor 27 is charged to the minimum trigger charging voltage V2 or more by the trigger power supply capacitor 15b during the period in which the IGBT 17b is off. Therefore, it is possible to generate a trigger voltage equal to or higher than the minimum trigger voltage for starting the next strobe light emission (pre-light emission).

  When an appropriate time elapses after the IGBT 17a is turned off, the IGBT 17a is turned on for the pre-flash of the second shooting. Thereafter, strobe light emission is repeatedly performed in the same manner, and pre-light emission and main light emission are performed every time photographing is performed.

  As described above, the trigger capacitor 27 is not limited to the charging voltage of the main capacitor 12 during the period when the IGBT 17a is turned off and the strobe light is not emitted, and the trigger power supply capacitor 15b Since the battery is charged, a trigger voltage higher than the minimum trigger voltage can be generated many times.

  FIG. 3 shows a circuit of the strobe device of the second embodiment. In addition, except being demonstrated below, it is the same as that of 1st Embodiment, The same code | symbol is attached | subjected to the same structural member, and the description is abbreviate | omitted.

  In the power supply unit 11, a first diode 31 and a second diode 32 are connected in parallel to one end of the secondary coil 22b. The direction of each diode 31 is determined by the charging direction. In this example, the anode is connected to one end of the secondary coil 22b.

  The first diode 31 feeds power to the main capacitor 12 by half-wave rectifying the output voltage of the step-up transformer 22. The charging control unit 10 detects the charging voltage of the main capacitor 12 from the cathode potential of the first diode 31. One second diode 32 rectifies the output voltage of the step-up transformer 22 and supplies power to the trigger power supply unit 15. The second diode 32 functions as a backflow prevention means for preventing the charged trigger power supply capacitor 15b and the trigger capacitor 27 from flowing a discharge current toward the main capacitor 12 to discharge the trigger power supply. A trigger power supply unit is configured together with the capacitor 15b. Even if comprised in this way, the effect similar to 1st Embodiment can be acquired.

  When the two diodes 31 and 32 are connected in parallel as in the second embodiment and the charging voltage of the main capacitor 12 is detected to control the charging, the main capacitor 12 is connected to the specified charging voltage. Even if the charging control is performed, the charging voltage of the trigger power supply capacitor 15b to the trigger capacitor 27 may become too higher than the specified charging voltage. This is due to the influence of the overshoot included in the output voltage obtained by diode rectifying the alternating current obtained by the boosting operation by the power supply unit 11, the characteristics of the circuit connected to the first diode 31, and the diode 32. This is because the charging voltage on the second diode 32 side tends to increase due to the difference from the characteristics of the connected circuit.

  As shown in FIG. 4, the strobe device of the third embodiment is provided with a damping resistor 34 that suppresses overshoot between the second diode 32 and the trigger power capacitor 15b, thereby providing the trigger power capacitor 15b or trigger. It is possible to prevent the charging voltage of the capacitor 27 from becoming too higher than the specified charging voltage.

  In the strobe device of the fourth embodiment shown in FIG. 5, the anode of the main capacitor side backflow prevention diode 37 is connected to the main capacitor 12 and the cathode of the rectifying diode 24 of the power supply unit 11, and this main capacitor side backflow prevention diode. The main capacitor 12 is charged by the power supply unit 11 through 37. That is, the power supply unit 11 is connected to the trigger power supply unit 15 including a series circuit of the main capacitor side backflow prevention diode 37 and the main capacitor 12 and a series circuit of the backflow prevention diode 15a and the trigger power supply capacitor 15b. .

  A smoothing capacitor 38 for smoothing the output voltage of the power supply unit 11 is provided between the connection point of the cathode of the rectifying diode 24 and each of the backflow prevention diodes 15a and 37 and the ground, and charging control is performed. The unit 10 is configured to control the operation of the power supply unit 11 by detecting the potential at this connection point, that is, the voltage across the terminals of the smoothing capacitor 38.

  With this configuration, since the overshoot of the output voltage output from the power supply unit 11 by the smoothing capacitor 38 can be suppressed, the charging voltage of the trigger power supply capacitor 15b is higher than the main capacitor 12. This can be suppressed. Further, the main capacitor side backflow prevention diode 37 can prevent a leakage current from flowing from the main capacitor 12 to the line for the charging control unit 10 to detect the voltage.

  FIG. 6 shows a fifth embodiment in which the opening and closing of the trigger discharge circuit and the light emission discharge circuit are independently controlled. In addition, although the case where the structure which controls opening / closing of each discharge circuit independently is applied to the said 4th Embodiment is demonstrated, in any 1st thru | or 3rd structure, it can implement similarly.

  The light emission control unit 40 independently turns on / off the trigger IGBT 41 as trigger switching means for opening and closing the trigger discharge circuit, and the light emission IGBT 42 as light emission switching means for opening and closing the light emission discharge circuit. And a switch control circuit 43 for controlling. The trigger IGBT 41 has a collector terminal connected to a connection point between the primary coil 28a and the discharge suppression resistor 16, and an emitter terminal grounded. The light emitting IGBT 42 has one collector electrode of the strobe discharge tube 13 connected to the collector terminal and the emitter terminal grounded.

  As shown in FIG. 7, when performing strobe light emission, the switch control circuit 43 turns on the IGBTs 41 and 42 and closes the trigger discharge circuit and the light emission discharge circuit, respectively. Thereby, in a state where the charging voltage of the main capacitor 12 is applied to the strobe discharge tube 13, the trigger voltage is applied to the strobe discharge tube 13 to start the strobe light emission.

  Immediately after the application of the trigger voltage is completed, the trigger IGBT 41 is turned off and the trigger discharge circuit is opened. Then, the light emitting IGBT 42 is turned off at the timing when the strobe light emission is to be ended, the light emission discharge circuit is opened, and the strobe light emission is ended.

  According to this, since the trigger discharge circuit for discharging the trigger capacitor 27 is closed for a short time, the discharge amount of the trigger power supply capacitor 15b connected in parallel to the trigger discharge circuit can be further reduced. For this reason, the number of times of light emission that can maintain the trigger capacitor 27 at the minimum trigger charging voltage V2 or more can be increased. Further, it is advantageous also when a capacitor having a small capacitance is used as the trigger power supply capacitor 15b.

  In each of the above-described embodiments, the strobe device is built in the digital camera, and the example in which the pre-flash and the main flash are performed by continuous shooting has been described. However, the present invention is not limited to being incorporated in a photographing apparatus such as.

It is a circuit diagram which shows the strobe device which implemented this invention. It is a graph which shows an example of the change of the charging voltage of each capacitor | condenser. It is a circuit diagram showing an example of a strobe device in which a rectifier diode is provided for each of a main capacitor and a trigger power supply capacitor. It is a circuit diagram showing an example of a strobe device provided with a damping resistor. It is a circuit diagram showing an example of a strobe device provided with a smoothing capacitor. It is a circuit diagram which shows the example of the strobe device which controls opening and closing of each discharge circuit of a trigger capacitor | condenser and a main capacitor | condenser independently. It is a graph which shows an example of the change of the charging voltage of each capacitor | condenser of the strobe device shown in FIG. It is a circuit diagram which shows an example of the circuit of the conventional strobe device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Charge control part 11 Power supply part 14 Trigger voltage generation part 15 Trigger power supply part 15a, 37 Backflow prevention transistor 15b Trigger power supply capacitor 27 Trigger capacitor 12 Main capacitor 13 Strobe discharge tube 17a, 41, 42 IGBT
31, 32 Rectifier diode 34 Damping resistor

Claims (8)

A power supply unit, a main capacitor that is charged by receiving power from the power supply unit, and a strobe discharge tube that discharges charges accumulated in the main capacitor and emits strobe light when a trigger voltage is applied. In the strobe device provided,
A trigger power supply that is charged by the power supply unit; and a backflow prevention unit that prevents current from flowing from the trigger power supply capacitor to the main capacitor, and is connected in parallel to the main capacitor And
A trigger voltage generator connected in parallel with the trigger power capacitor and having a trigger capacitor charged by a voltage between terminals of the trigger power capacitor, and generating a trigger voltage by discharging the trigger capacitor;
Discharge suppression means for suppressing discharge of the trigger power supply capacitor at the time of discharging of the trigger capacitor and allowing charging of the trigger capacitor by the trigger power supply capacitor immediately after discharge of the trigger capacitor is provided. Strobe device.   The backflow prevention means is a backflow prevention diode, and the trigger power supply unit is a series circuit of the backflow prevention diode and the trigger power supply capacitor, and is connected to the power supply unit in parallel with the main capacitor. The strobe device according to claim 1, wherein the strobe device is provided.   The power supply unit rectifies a high-voltage alternating current and supplies power to the main capacitor, and is connected in parallel in the same direction as the first diode, and rectifies the high-voltage alternating current and supplies the trigger power supply unit. The strobe device according to claim 1, further comprising a second diode as the backflow preventing means while supplying power to the power supply.   4. The strobe device according to claim 3, wherein a damping resistor for suppressing an overshoot of a voltage output from the second diode is provided between the second diode and the trigger power supply capacitor.   5. The charging control unit according to claim 4, further comprising: a charge control unit that detects a voltage between terminals of the main capacitor and controls an operation of the power supply unit so that the voltage between the terminals maintains a predetermined charging voltage. Strobe device. A series circuit of a first backflow prevention diode and the main capacitor, the trigger power supply unit including a second backflow prevention diode as the backflow prevention means, and a smoothing capacitor for smoothing the output voltage of the power supply unit The strobe device according to claim 1, wherein the power supply unit is connected in parallel.   The strobe according to claim 6, further comprising a charge control unit that controls an operation of the power supply unit so that the main capacitor holds a predetermined specified charging voltage based on a voltage between terminals of the smoothing capacitor. apparatus.   Trigger switching means for opening and closing the trigger discharge circuit of the trigger capacitor when generating the trigger voltage, and provided separately from the trigger switching means, and when the main capacitor discharges via the strobe discharge tube The light emission control switching means for opening and closing the light emission discharge circuit, and in the case of strobe light emission, the trigger discharge circuit is opened immediately after the trigger discharge circuit and the light emission discharge circuit are closed and the strobe light emission is started. 2. The apparatus according to claim 1, further comprising switch control means for controlling the trigger switching means and the light emission control switching means so as to close the light emission discharge circuit at a timing to stop the strobe light emission thereafter. 8. The strobe device according to any one of 7 above.

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