JP4230652B2 - Flash light emitting circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flash light emitting circuit that emits flash light.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known a camera that takes a picture by emitting flash light in synchronization with a shutter operation when subject brightness is insufficient. Such a camera is provided with a flash light emission circuit for emitting flash light. The flashlight circuit is applied to a booster circuit, a main capacitor that stores power boosted by the booster circuit, a light-emitting tube that emits flashlight by the power emitted from the main capacitor, and a trigger electrode of the light-emitting tube It has a trigger coil for generating a trigger voltage and a switch element for controlling the current flowing through the arc tube. As the switch element, an IGBT (Insulated Gate Bipolar Transistor) element is generally used. In the flash light emitting circuit configured as described above, the magnitude of the rise of the current flowing in the IGBT element is detected, and when the magnitude reaches a value corresponding to a desired light emission quantity, the IGBT element is turned off to emit light. The current flowing through the tube is stopped, and thereby the exposure amount is controlled. For example, when shooting a subject in a long-distance area, the IGBT element is turned off when the current flowing through the IGBT element sufficiently rises, and this causes the subject to be irradiated with a sufficient amount of flash light, resulting in insufficient exposure. Is prevented. On the other hand, when photographing an object in a short distance area, the IGBT element is turned off at an early stage when the current flowing through the IGBT element does not yet rise sufficiently, and the subject is irradiated with a small amount of flash light for exposure. Over is prevented.
[0003]
[Problems to be solved by the invention]
In the above-described flash light emitting circuit, in order to irradiate a subject with a sufficient amount of flash light for long-distance shooting, a current having a sufficiently large peak value in an IGBT element (for example, in a light emitting tube for a compact camera) Current having a peak value of about 250 A) needs to flow. In order to control a current having such a large peak value, an expensive IGBT element having a relatively large size is required. In close-up photography, the IGBT element is detected by detecting the magnitude of the current corresponding to the desired amount of emitted light in a very short time at the initial time when the current does not rise sufficiently, that is, when the current change rate is large. There is a problem that it is necessary to control to an off state, and the control is complicated.
[0004]
In view of the above circumstances, an object of the present invention is to provide a flash light emitting circuit in which the control of the amount of emitted light is simplified and the cost is reduced.
[0005]
[Means for Solving the Problems]
The first flash light emitting circuit of the present invention that achieves the above object is that a capacitor is charged and the electric power charged in the capacitor is passed through a discharge loop in which an arc tube is arranged in the middle. In the flash light emitting circuit that emits flash light from the arc tube by discharging,
A switching element that is arranged in the discharge loop and opens and closes the discharge loop according to control;
A control unit for driving the switch element in a pulsed manner;
A timer for measuring a predetermined time corresponding to a desired amount of emitted light after the start of light emission,
The control unit is programmed with a series of a plurality of pulse blocks that may have different pulse sequences for driving the switch elements, and drives the switch elements based on the program. And
The control unit is configured to stop the pulse driving of the switch element in response to time-up of the timer and control the switch element to be in an OFF state.
[0006]
The first flash light emitting circuit according to the present invention measures a predetermined time corresponding to a desired light emission amount with a timer, stops the pulse driving of the switch element when the timer expires, and controls the switch element to be in an OFF state. Therefore, in the light amount control, a predetermined time corresponding to the desired light emission amount may be set in the timer, and thus the control of the light emission amount is simplified. Further, since the switch element is driven by a plurality of pulse blocks, an inexpensive switch element having a relatively small allowable current can be employed, and the cost can be reduced.
[0007]
Here, it is preferable that the control unit controls the switch element to be in an OFF state at a timing when driving of the switch element by one pulse block is completed in response to time-up of the timer.
[0008]
In this way, when the switch element is controlled to be in the OFF state at the timing when driving by one pulse block is completed in response to the time-up of the timer, the amount of emitted light can be controlled in units of one pulse block. Control is further simplified.
[0009]
In addition, it is a preferable aspect that the control unit controls the switch element in an OFF state even when the switch element is driven by one pulse block in response to the time-up of the timer. .
[0010]
In the middle of driving here, for example, when one pulse block is composed of five pulses, the switch element may be turned off when the third pulse ends, or the third pulse The switch element may be turned off in the middle of the pulse. In this way, when the switch element is controlled to be turned off even when the switch element is driven by one pulse block in response to the timer time-up, the emitted light can be stopped immediately, so that high accuracy can be obtained. Thus, the amount of emitted light can be controlled.
[0011]
In addition, the second flash light emitting circuit of the present invention that achieves the above object charges a capacitor and passes the electric power charged in the capacitor through a discharge loop in which a light emitting tube is arranged in the middle. In the flash light emitting circuit that emits flash light from the arc tube by discharging,
A switching element that is arranged in the discharge loop and opens and closes the discharge loop according to control;
A control unit for driving the switch element in a pulsed manner;
A voltage detector that detects the voltage of the capacitor before and after the start of light emission,
The control unit is programmed with a series of a plurality of pulse blocks that may have different pulse sequences for driving the switch elements, and drives the switch elements based on the program. And
In the control unit, the voltage detection unit detects that the voltage of the capacitor has decreased to a predetermined voltage corresponding to the voltage detected before the start of light emission of the capacitor and a desired light emission amount. In response, the pulse drive of the switch element is stopped and the switch element is controlled to be in an OFF state.
[0012]
In the second flash light emitting circuit of the present invention, it is detected that the voltage of the capacitor has decreased to a predetermined voltage corresponding to the voltage detected before the light emission of the capacitor is started and the desired light emission amount. In response to this, the pulse drive of the switch element is stopped and the switch element is controlled to be in the OFF state. Therefore, in the light amount control, it is only necessary to detect the predetermined voltage of the capacitor, and thus the control of the light emission amount is simplified. The Further, since the switch element is driven by a plurality of pulse blocks, an inexpensive switch element having a relatively small allowable current can be employed, and the cost can be reduced.
[0013]
Here, the control unit turns off the switching element at the timing when the driving of the switching element by one pulse block is completed in response to the detection that the voltage detecting unit has decreased to the predetermined voltage. It is preferable to control the state.
[0014]
By controlling in this way, the amount of emitted light can be controlled in units of one pulse block, and the control of the amount of emitted light is further simplified.
[0015]
Further, the control unit turns off the switch element even during the driving of the switch element by one pulse block in response to the fact that the voltage detector detects that the voltage has dropped to the predetermined voltage. It is also a preferred embodiment that the state is controlled.
[0016]
By controlling in this way, the emitted light can be stopped immediately, so that the amount of emitted light can be controlled with high accuracy.
[0017]
Furthermore, the third flash light emitting circuit of the flash light emitting circuit of the present invention that achieves the above object charges a capacitor, and the power charged in the capacitor passes through a discharge loop in which a light emitting tube is arranged in the middle. In the flash light emitting circuit that emits flash light from the arc tube by discharging,
A switching element that is arranged in the discharge loop and opens and closes the discharge loop according to control;
A controller for driving the switching element in a pulsed manner;
The control unit is programmed with a series of a plurality of pulse blocks that may have different pulse sequences for driving the switch elements, and drives the switch elements based on the program. And
The control unit stops the pulse drive of the switch element at the timing when the pulse drive of the switch element corresponding to the number of pulses or the number of pulse blocks corresponding to the desired amount of emitted light is finished, and controls the switch element to be in an OFF state. It is characterized by being.
[0018]
The third flash light emitting circuit of the present invention stops the pulse drive of the switch element at the timing when the pulse drive of the number of pulses or the number of pulse blocks corresponding to the desired light emission amount is finished, and turns off the switch element. In order to control the amount of light, the number of pulses or the number of pulse blocks corresponding to the desired amount of emitted light may be set in the control unit when controlling the amount of light, and thus control of the amount of emitted light is simplified. Further, since the switch element is driven by a plurality of pulse blocks, an inexpensive switch element having a relatively small allowable current can be employed, and the cost can be reduced.
[0019]
Here, the control unit controls the switch element to be in an OFF state even in the middle of one pulse block at the timing when the pulse drive of the switch element corresponding to the number of pulses corresponding to the desired light emission amount is completed. It is preferable.
[0020]
In this way, since the emitted light can be stopped immediately if the switch element is controlled to be in an OFF state even in the middle of one pulse block, the amount of emitted light can be controlled with high accuracy.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described. Here, a flash light emitting circuit mounted on the camera will be described.
[0022]
FIG. 1 is a diagram showing an embodiment of a first flash light emitting circuit of the present invention.
[0023]
A flash light emitting circuit 100 shown in FIG. 1 includes a booster circuit 11 connected to a built-in battery 1 for controlling the entire camera. The booster circuit 11 boosts the voltage from the internal battery 1 to a predetermined voltage.
[0024]
Further, the flash light emitting circuit 100 is provided with a main capacitor 13_1 that accumulates the electric power boosted by the booster circuit 11 via the diode 12_1. A resistance element 14_1 and a trigger capacitor 13_2 are connected in series to both ends of the main capacitor 13_1.
[0025]
Further, the flash light emitting circuit 100 includes an arc tube 15, a trigger coil 16, an IGBT element 17 (an example of a switch element according to the present invention), a diode 12_2, and resistance elements 14_4 and 14_5.
[0026]
The arc tube 15 includes an anode 15a, a cathode 15b, and a side electrode 15c, and xenon (XE) gas is sealed inside. The arc tube 15 emits light by the electric power emitted from the main capacitor 13_1. The trigger coil 16 includes a primary winding 16a having a predetermined number of turns and a secondary winding 16b having a number of turns larger than the number of turns. One end of the primary winding 16a is connected to the cathode 15b of the arc tube 15 and the connection point of the resistance element 14_1 and the trigger capacitor 13_2. On the other hand, one end of the secondary winding 16 b is connected to the side electrode 15 c of the arc tube 15. The other ends of the primary winding 16a and the secondary winding 16b are connected to the collector of the IGBT element 17 and the anode of the bypass diode 12_2. The base of the IGBT element 17 is connected to the ground GND (the negative terminal of the built-in battery 1) via the resistance element 14_4, and is connected to the control circuit 19 described later via the resistance element 14_5. The emitter of the IGBT element 17 is connected to the ground GND. Further, the cathode of the bypass diode 12_2 is connected to the anode 15a of the arc tube 15. The anode 15a of the arc tube 15 is connected to the + side of the main capacitor 13_1.
[0027]
The trigger coil 16 transmits electric power flowing through the trigger capacitor 13_2 to the secondary winding 16b to give a trigger voltage to the arc tube 15. The primary coil 16a of the trigger coil 16 includes the arc tube 15 and the trigger coil 16_2. Together with the IGBT element 17, it is arranged in a discharge loop through which the electric power discharged from the main capacitor 13_1 flows. Further, when the IGBT element 17 is turned off, the bypass diode 12_2 has a large counter electromotive force generated in the primary side winding 16a because the current flowing in the primary side winding 16a immediately before that is suddenly cut off. The current is caused to flow, so that a large voltage due to the back electromotive force is prevented from being applied to the IGBT element 17, and the destruction of the IGBT element 17 is prevented.
[0028]
The IGBT element 17 is a switch element that is arranged in a discharge loop in which the power charged in the main capacitor 13_1 is discharged and opens and closes the discharge loop according to control, and in the state where the charging of the main capacitor 13_1 is completed. When the electric power of the main capacitor 13_1 is discharged while the discharge loop is formed, the allowable current is lower than the peak value of the discharge current flowing through the discharge loop.
[0029]
The flash light emitting circuit 100 is provided with a control circuit 19 and a timer 20. The timer 20 measures a predetermined time corresponding to a desired amount of emitted light after the start of light emission. The control circuit 19 is obtained by programming a series of a plurality of pulse blocks in which the pulse sequence for driving the IGBT element 17 may be different from each other, and drives the IGBT element 17 based on the program. Further, the control circuit 19 stops the pulse drive of the IGBT element 17 in response to the time-up of the timer 20 and controls the IGBT element 17 to be in an OFF state. More specifically, the control circuit 19 controls the IGBT element 17 to be turned off at the timing when the driving of the IGBT element 17 by one pulse block is completed in response to the timer 20 being timed up.
[0030]
FIG. 2 is a diagram showing a part of the control circuit shown in FIG. 1 together with the main capacitor, arc tube, trigger coil, IGBT element, and the like.
[0031]
As shown in FIG. 2, the control circuit 19 includes a resistance element 19a. ₁ , 19a ₂ Are connected to each other, a P-channel transistor 19a, an N-channel MOSFET 19b, and a resistance element 19c disposed between the P-channel transistor 19a and the N-channel MOSFET 19b. The gate of the N-channel MOSFET 19b is connected to the resistance element 19a. ₂ Is connected to the base of the P-channel transistor 19a and receives the pulse bar signal FT_. The voltage VCC obtained by stabilizing the voltage of the built-in battery 1 by a regulator (not shown) is input to the emitter of the P-channel transistor 19a. Further, the voltage HV boosted by the booster circuit 11 (see FIG. 1) is applied to the main capacitor 13_1.
[0032]
FIG. 3 is a diagram showing each example in which the pulse drive of the IGBT element is stopped in response to the time-up of the timer shown in FIG.
[0033]
First, the operation of the flash light emitting circuit 100 will be described with reference to FIGS. 1, 2, and 3, and then Examples 1 to 4 shown in FIG. 3 will be described.
[0034]
In the present embodiment, a relatively inexpensive IGBT element 17 having an allowable current with a peak value of about 130 A is used. The control circuit 19 outputs a pulse signal FT in which a series of a plurality of pulse blocks whose pulse sequences for pulse driving the IGBT element 17 may be different from each other so as not to exceed the allowable current is programmed. . In the initial initial sequence, power from the internal battery 1 is boosted by the booster circuit 11, and the voltage MC of the main capacitor 13_1 is at the maximum value (320V). Further, the pulse bar signal FT_ shown in FIG. 2 is at the “H” level. Therefore, the P-channel transistor 19a and the N-channel MOSFET 19b are in an off state and an on state, respectively. Therefore, 'L' level is input to the base of the IGBT element 17 as the pulse signal FT via the resistance element 14_5, and the IGBT element 17 is in the OFF state. In addition, power is stored in the trigger capacitor 13_2 through the resistance element 14_1.
[0035]
Next, a pulse of “L” level is input as the pulse bar signal FT_. Then, the P-channel transistor 19a and the N-channel MOSFET 19b are turned on and off, so that a pulse of “H” level is input to the base of the IGBT element 17 via the resistance element 14_5 as the pulse signal FT. . Then, the IGBT element 17 is turned on, and the electric charge accumulated in the trigger capacitor 13_2 is discharged through the path of the primary coil 16a → IGBT element 17 → ground GND of the trigger coil 16. As a result, a current flows through the primary winding 16a, and an electromotive force is induced in the secondary winding 16b. Here, since the number of turns of the secondary winding 16b is larger than the number of turns of the primary winding 16a, the electromotive force induced in the secondary winding 16b is amplified and increased. Since such a large electromotive force is applied to the side electrode 15c of the arc tube 15 as a trigger voltage, the xenon gas sealed in the arc tube 15 is excited and the (+) side of the main capacitor 13_1 → the arc tube 15 A current IC flows through the path of the anode 15 a → the cathode 15 b of the arc tube 15 → the primary winding 16 a of the trigger coil 16 → the IGBT element 17 → the ground GND, and flash light is generated from the arc tube 15. In this manner, flash light is emitted in the initial sequence. In this initial sequence, a pulse having a relatively large pulse width (for example, a pulse having a width of 15 μS) is output as the pulse signal FT in order to stabilize the excited state of the arc tube 15 and reliably emit the flash light. . Hereinafter, the process proceeds to the intermediate sequence and the final sequence.
[0036]
Next, Examples 1 to 4 shown in FIG. 3 will be described. In the flash light emitting circuit 100 of this embodiment, a predetermined time corresponding to a desired light emission amount is set in the timer 20, and the predetermined time is counted by the timer 20 from the time when the initial sequence is started. The intermediate sequence includes a first pulse block composed of three relatively narrow pulses, a second pulse block composed of four pulses wider than the pulse width of the first pulse block, and a second pulse. It is composed of three pulse blocks including a third pulse block composed of one pulse wider than the pulse width of the block. In Example 1, the control circuit 19 turns off the IGBT element 17 at the time when the second of the three pulses constituting the first pulse block ends in response to the timer 20 being timed up. . Further, in Example 2, the control circuit 19 turns off the IGBT element 17 in the middle of one pulse constituting the third pulse block in response to the timer 20 being timed up. Further, in Example 3, the control circuit 19 turns off the IGBT element 17 in the middle of the second pulse constituting the second pulse block in response to the timer 20 being timed up. Further, in Example 4, the control circuit 19 receives the timer 20 time-up, and turns off the IGBT element 17 in the middle of the pulse in the final sequence. When the IGBT element 17 is controlled to be in the OFF state in this manner, the emitted light is immediately stopped, so that the amount of emitted light can be controlled with high accuracy.
[0037]
FIG. 4 is a flowchart of a routine for controlling the pulse drive of the IGBT element in response to the time-up of the timer shown in FIG.
[0038]
First, in step S21, a predetermined time corresponding to a desired amount of emitted light is set (set) in the timer 20. Next, in step S22, a light emission command is output from a microcomputer (not shown). In step S23, in response to this, the control circuit 19 executes an initial sequence. Next, it progresses to step S24 and mode selection is performed. There are four types of modes: macro mode, short distance mode, medium distance mode, and long distance mode. If it is determined that the current mode is the macro mode, the process proceeds to step S25 to execute the intermediate sequence part 1 up to the initial stage of the intermediate sequence shown in Example 1 of FIG. On the other hand, if it is determined that the short-distance mode is selected, the process proceeds to step S26 to execute the intermediate sequence part 2 up to the middle of the intermediate sequence shown in Example 3 of FIG. Further, if it is determined that the vehicle is in the intermediate distance mode, the process proceeds to step S27 to execute the intermediate sequence part 3 up to the last part of the intermediate sequence shown in Example 2 of FIG. On the other hand, if it is determined that the user is in the long-distance mode, the process proceeds to step S28 to execute the final sequence part up to the middle of the final sequence shown in Example 4 of FIG.
[0039]
The flash light emitting circuit 100 according to the present embodiment measures a predetermined time corresponding to a desired light emission amount by the timer 20, receives the time-up of the timer 20, stops the pulse driving of the IGBT element 17, and turns off the IGBT element 17. Therefore, in the light amount control, a predetermined time corresponding to the desired light emission amount may be set in the timer 20, and thus the control of the light emission amount is simplified. Further, since the IGBT element 17 is driven by a plurality of pulse blocks, an inexpensive IGBT element 17 having a relatively small allowable current can be adopted, and the cost can be reduced.
[0040]
In the present embodiment, an example has been described in which the IGBT element 17 is controlled to be turned off even when the IGBT element 17 is driven by one pulse block in response to the timer 20 being timed up. Therefore, the IGBT element 17 may be controlled to be turned off at the timing when the driving of the IGBT element 17 by one pulse block is completed. In this way, the amount of emitted light can be controlled in units of one pulse block, and the control of the amount of emitted light is further simplified.
[0041]
In the present embodiment, the example in which the predetermined time calculated from the time when the initial sequence is started is set in the timer 20, but the predetermined time calculated from the time when the initial sequence is completed may be set in the timer 20. . In this way, light emission is performed in accordance with the time from the intermediate sequence excluding the initial sequence for performing stable light emission, so that the amount of emitted light can be controlled with high accuracy.
[0042]
Further, the timer 20 may not start measuring a predetermined time in the initial sequence, but may start measuring after the end of the initial sequence. In this way, light emission is performed in accordance with the time from the intermediate sequence excluding the initial sequence for performing stable light emission, so that the amount of emitted light can be controlled with high accuracy.
[0043]
FIG. 5 is a diagram showing an embodiment of the second flash light emitting circuit of the present invention.
[0044]
In addition, the same code | symbol is attached | subjected about the same component as the component of the flash light emission circuit 100 shown in FIG. 1, and duplication description is abbreviate | omitted.
[0045]
The flash light emitting circuit 200 shown in FIG. 5 includes resistance elements 14_2 and 14_3 connected to both ends of the main capacitor 13_1, a voltage detection circuit 18, and a control circuit 29.
[0046]
The voltage detection circuit 18 detects the voltage of the main capacitor 13_1 before and after the start of light emission based on the voltage at the connection point of the resistance elements 14_2 and 14_3 connected to both ends of the main capacitor 13_1.
[0047]
The control circuit 29 is a program in which a series of a plurality of pulse blocks whose pulse sequences for driving the IGBT element 17 may be different from each other is programmed, and drives the IGBT element 17 based on the program. Further, in the control circuit 29, the voltage of the main capacitor 13_1 is lowered by the voltage detection circuit 18 to a predetermined voltage corresponding to the voltage detected before the light emission of the main capacitor 13_1 and the desired light emission amount. When this is detected, the pulse drive of the IGBT element 17 is stopped, and the IGBT element 17 is controlled to be in an OFF state. Further, the control circuit 29 detects that the voltage detection circuit 18 has lowered the voltage to the predetermined voltage, and controls the IGBT element 17 even during the driving of the IGBT element 17 by one pulse block. Control to off state.
[0048]
FIG. 6 is a diagram showing a state in which the pulse driving of the IGBT element is stopped in response to the fact that the voltage of the main capacitor has been reduced to the predetermined first voltage by the voltage detection circuit shown in FIG. It is.
[0049]
The main capacitor 13_1 is charged to a voltage MC of 320V. In the initial sequence, a pulse having a relatively large pulse width (for example, 15 μS) is output as the pulse signal FT in order to stabilize the excited state of the arc tube 15 and to reliably emit the flash light. Note that when the IGBT element 17 is first turned on, noise is generated, and then a current IC flows and flashing is generated from the arc tube 15. Along with this, the voltage MC gradually decreases. As described above, the voltage MC is detected by the voltage detection circuit 18 based on the voltage at the connection point of the resistance elements 14_2 and 14_3 connected to both ends of the main capacitor 13_1. In this manner, flash light is emitted in the initial sequence.
[0050]
Next, in the intermediate sequence, the first and second pulses are input as the pulse signal FT, and two pulse currents IC corresponding to the first and second pulses flow through the arc tube 15, and these 2 Flash is generated from the arc tube 15 in response to two pulse currents IC. Along with this, the voltage MC further decreases, and the voltage MC of the main capacitor 13_1 becomes a predetermined first level corresponding to the voltage MC (320V) detected before the light emission of the main capacitor 13_1 and the desired light emission amount. The voltage drops to the voltage (voltage indicated by the dotted line in FIG. 6). In the control circuit 29, when the voltage detection circuit 18 detects that the voltage MC of the main capacitor 13_1 has decreased to the predetermined first voltage, the pulse drive of the IGBT element 17 is stopped and the control circuit 29 The IGBT element 17 is controlled to be turned off.
[0051]
FIG. 7 shows the pulse drive of the IGBT element in response to the detection that the voltage of the main capacitor has dropped to a predetermined second voltage that is lower than the predetermined first voltage shown in FIG. It is a figure which shows a mode that it stops.
[0052]
In FIG. 6, in response to the detection that the first and second pulses have been reduced to the predetermined first voltage after the first and second pulses are input in the intermediate sequence, the IGBT element 17 is stopped from being pulse driven. Although the element 17 is controlled to be in the OFF state, in FIG. 7, after the first and second pulses are input in the intermediate sequence, the third pulse is further input, and then the process proceeds to the final sequence due to a relatively large pulse. In other words, so-called DC light emission (normal single light emission) is performed. As a result, the voltage MC rapidly decreases to a predetermined second voltage (voltage indicated by a dotted line in FIG. 7). In response to detecting that the voltage has dropped to the predetermined second voltage, the control circuit 29 stops the pulse driving of the IGBT element 17 in the middle of the pulse in the final sequence, and turns the IGBT element 17 off. Control.
[0053]
The flash light emitting circuit 200 according to the present embodiment detects that the voltage MC of the main capacitor 13_1 has dropped to a predetermined voltage corresponding to the voltage detected before the main capacitor 13_1 starts light emission and the desired amount of emitted light. In response to this, the pulse drive of the IGBT element 17 is stopped and the IGBT element 17 is controlled to be in an OFF state. Therefore, in the light amount control, the predetermined first and second voltages of the main capacitor 13_1 are set. Therefore, the control of the amount of emitted light is simplified.
[0054]
The control circuit 29 receives the fact that the voltage detecting circuit 18 has detected that the voltage has dropped to the predetermined first or second voltage, and at the timing when the driving of the IGBT element 17 by one pulse block is completed. Since the IGBT element 17 is controlled to be in the off state, the control of the amount of emitted light is further simplified.
[0055]
The control circuit 29 turns off the IGBT element 17 even during the driving of the IGBT element 17 by one pulse block in response to the voltage detection circuit 18 detecting that the voltage has dropped to a predetermined voltage. You may control to a state. When the IGBT element 17 is controlled to be in the OFF state in this way, the amount of emitted light can be controlled with high accuracy.
[0056]
FIG. 8 is a diagram showing an embodiment of the third flash light emitting circuit of the present invention.
[0057]
In addition, the same code | symbol is attached | subjected about the same component as the component of the flash light emission circuit 100 shown in FIG. 1, and duplication description is abbreviate | omitted.
[0058]
The flash light emission circuit 300 shown in FIG. 8 includes a control circuit 39 having a counter 39a. In the counter 39a, the number of pulses or the number of pulse blocks corresponding to the desired light emission quantity is set. The control circuit 39 is a program in which a series of a plurality of pulse blocks that may have different pulse sequences for driving the IGBT element 17 are programmed, and drives the IGBT element 17 based on the program. . The control circuit 39 counts the edges of the pulse signal FT with the counter 39a, stops the pulse drive of the IGBT element 17 when the number of pulses or the number of pulse blocks corresponding to the desired light emission quantity is reached, and the IGBT element. 17 is controlled to an off state. For this reason, in the light amount control, the counter 39a may be set with the number of pulses or the number of pulse blocks corresponding to the desired amount of emitted light, and thus the control of the amount of emitted light is simplified. Further, the control circuit 39 controls the IGBT element 17 to be in the OFF state even in the middle of one pulse block at the timing when the pulse driving of the IGBT element 17 for the number of pulses corresponding to the desired amount of emitted light is completed. To do. For this reason, the amount of emitted light can be controlled with high accuracy.
[0059]
【The invention's effect】
As described above, according to the flash light emitting circuit of the present invention, the control of the amount of emitted light can be simplified and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a first flash light emitting circuit of the present invention.
FIG. 2 is a diagram showing a part of the control circuit shown in FIG. 1 together with a main capacitor, an arc tube, a trigger coil, an IGBT element, and the like.
3 is a diagram showing examples in which pulse driving of an IGBT element is stopped in response to time-up of a timer shown in FIG. 1. FIG.
4 is a flowchart of a routine for controlling pulse driving of an IGBT element in response to time-up of a timer shown in FIG.
FIG. 5 is a diagram showing an embodiment of a second flash light emitting circuit of the present invention.
6 is a diagram illustrating a state in which pulse driving of the IGBT element is stopped in response to detection that the voltage of the main capacitor has decreased to a predetermined first voltage by the voltage detection circuit illustrated in FIG. 5; It is.
FIG. 7 shows that it is detected that the voltage of the main capacitor has dropped to a predetermined second voltage that is lower than the predetermined first voltage shown in FIG. 6; It is a figure which shows a mode that it stops.
FIG. 8 is a diagram showing an embodiment of a third flash light emitting circuit of the present invention.
[Explanation of symbols]
1 Built-in battery
100, 200, 300 Flash emission circuit
11 Booster circuit
12_1, 12_2 diode
13_1 Main capacitor
13_2 Trigger capacitor
14_1, 14_2, 14_3, 14_4, 14_5, 19a ₁ , 19a ₂ 19c Resistive element
15 arc tube
15a anode
15b cathode
15c Side electrode
16 Trigger coil
16a Primary winding
16b Secondary winding
17 IGBT element
18 Voltage detection circuit
19, 29, 39 Control circuit
19a P-channel transistor
19b N-channel MOSFET
20 timer
39a counter

Claims (2)

In a flash light emitting circuit that emits flash light from the arc tube by charging the capacitor and discharging the electric power charged in the capacitor via a discharge loop in which the arc tube is arranged in the middle,
A switching element disposed in the discharge loop and opening and closing the discharge loop according to control;
A control unit for driving the switch element in pulses;
A timer for measuring a predetermined time corresponding to a desired amount of emitted light after the start of light emission,
The control unit is programmed with a series of pulse blocks in which a sequence of pulses for driving the switch element may be different from each other, and drives the switch element based on the program And
The control unit receives the time-up of the timer, and at the timing when driving of the switch element by one pulse block driving the switch element of the series of pulse blocks is completed, A flash light emission circuit characterized by stopping pulse driving and controlling the switch element to an off state. In a flash light emitting circuit that emits flash light from the arc tube by charging the capacitor and discharging the electric power charged in the capacitor via a discharge loop in which the arc tube is arranged in the middle,
A switching element disposed in the discharge loop and opening and closing the discharge loop according to control;
A control unit for driving the switch element in pulses;
A voltage detector that detects the voltage of the capacitor before and after the start of light emission,
The control unit is programmed with a series of pulse blocks in which a sequence of pulses for driving the switch element may be different from each other, and drives the switch element based on the program And
The controller detects that the voltage of the capacitor has dropped to a predetermined voltage corresponding to a voltage detected before the start of light emission of the capacitor and a desired amount of light emitted by the voltage detector. In response, the pulse driving of the switching element is stopped and the switching element is turned off at the timing when the driving of the switching element by one pulse block driving the switching element of the series of pulse blocks is completed. A flash light emitting circuit characterized by being controlled to a state.

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