JP3554290B2 - Strobe device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a strobe device, for example, to a strobe device suitable for being built in or externally attached to various cameras.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a so-called strobe device that instantaneously illuminates a subject at the time of shooting has been widely used as a camera for shooting a silver halide photograph or a digital camera for shooting an image using an image sensor.
[0003]
The above-described conventional strobe device generally includes a charging circuit that boosts a power supply voltage and charges energy for light emission of a discharge tube, and a trigger circuit that promotes (starts) light emission. As disclosed in Japanese Patent No. 241860, a winding transformer is employed for each of the charging circuit and the trigger circuit.
[0004]
[Problems to be solved by the invention]
However, since the winding transformer generally has a large external shape and a heavy weight, it is not preferable for a strobe device of a camera which is carried and carried by a user.
[0005]
In view of this, the applicant of the present application has proposed in Japanese Patent Application No. 2000-31384 (which was not disclosed at the time of filing of the present application) that, as shown in FIG. We have proposed a strobe device that employs a piezoelectric transformer that has excellent flexibility in the charging circuit and the trigger circuit.
[0006]
That is, the strobe device shown in FIG. 7 is roughly composed of a charging circuit 21, a trigger circuit 22, a discharge capacitor 23, and a discharge tube 24.
[0007]
In this circuit, when the switch 52 is closed and the switch 58 is open, the drive circuit 53 drives the piezoelectric transformer 54 according to the oscillation signal output from the oscillation circuit 51. After the output voltage of the piezoelectric transformer 54 is rectified by a rectifier circuit including diodes 55 and 56, the output voltage is charged to the discharge capacitor 23 as electric energy for causing the discharge tube 24 to emit light. When the switch 52 is open and the switch 58 is closed, the driving circuit 59 drives the piezoelectric transformer 60 according to the oscillation signal output from the oscillation circuit 57, and the high voltage output from the piezoelectric transformer is used as a trigger. Then, the discharge tube 24 emits a flash due to the energy charged in the discharge capacitor 23.
[0008]
However, in order to meet the demand for further downsizing of the strobe device, it is not sufficient to simply employ piezoelectric transformers for the charging circuit 21 and the trigger circuit 23 as shown in FIG.
[0009]
Accordingly, an object of the present invention is to provide a strobe device having a simple circuit configuration and excellent space saving.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a strobe device according to the present invention has the following configuration.
[0011]
That is, a discharge tube for flash (4), a capacitor (3) for storing electric energy for causing the discharge tube to emit light, a charging circuit (1) for charging the capacitor with electric energy, and prompting discharge of the discharge tube. A strobe device including a trigger circuit (2) for generating a high-voltage signal, wherein the booster circuit includes one piezoelectric transformer and is used as a booster of the charging circuit and the trigger circuit. 13) and switching means (14, 14A to 14D) for switching the booster circuit for the charging circuit or the trigger circuit so as to apply the output voltage of the piezoelectric transformer to the capacitor or the discharge tube. It is characterized by having.
[0012]
In a preferred embodiment, the switching means is at least one switch or switching element (14) provided in series on a line connecting the output of the piezoelectric transformer and the capacitor. (See FIG. 1).
[0013]
In another preferred embodiment, the switching means includes at least one switch for switching an output of the piezoelectric transformer to a first line connected to the capacitor or a second line connected to a trigger line of the discharge tube. The switching elements (14A to 14D) (see FIGS. 2 and 3). In this case, when the switch or the switching element performs a switching operation, the output of the piezoelectric transformer is completely open. In order to prevent this, a high impedance load (17) is preferably connected in parallel with the output of the piezoelectric transformer.
[0014]
In any of the above configurations, in both the charging circuit and the trigger circuit, the oscillation circuit (11A) of the piezoelectric transformer can output a plurality of types of oscillation signals having different frequencies, and the switching operation by the switching unit is performed. It is preferable to output any one of these oscillation signals in accordance with the above (see FIG. 4). Specifically, as shown in FIG. 5C, the frequency of the oscillation signal may be switched from a low frequency for charging to a high frequency for trigger.
[0015]
Alternatively, the charging circuit further includes a charging voltage detection circuit (18) for detecting a charging voltage of the capacitor, and in the charging circuit and the trigger circuit, the oscillation circuit (11A) of the piezoelectric transformer outputs a plurality of types of oscillation signals having different frequencies. It is possible to output, and it is preferable to output one of the oscillation signals according to the output signal of the charging voltage detection circuit (see FIG. 6). Specifically, as shown in FIG. 5C, the frequency of the oscillation signal may be switched from a low frequency for charging to a high frequency for trigger.
[0016]
It should be noted that a strobe device having any of the above-described configurations is suitable for use with a camera that is built in or externally attached to various cameras, in which case the switching unit is operated in accordance with a shutter operation of the camera. It should work.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a strobe device according to the present invention will be described in detail with reference to the drawings.
[0018]
[First Embodiment]
FIG. 1 is a block diagram illustrating a circuit configuration of the strobe device according to the first embodiment.
[0019]
The strobe device shown in FIG. 1 is roughly divided into a discharge tube (for example, a xenon discharge tube) 4 for flash, a discharge capacitor 3 for storing electric energy for causing the discharge tube 4 to emit light, and a charging circuit 1 for charging the discharge capacitor 3 with electric energy. And a trigger circuit 2 for generating a high voltage signal for urging the discharge tube 4 to discharge.
[0020]
The charging circuit 1 and the trigger circuit 2 include a pair of boosting circuits including an oscillation circuit 11, a driving circuit 12, and a piezoelectric transformer 13 as common boosting means, and the driving circuit 12 outputs from the oscillation circuit 11. The piezoelectric transformer 13 is driven according to an oscillation signal having a predetermined frequency.
[0021]
The switch (or switching element) 14 is provided in series with the line connecting the output of the piezoelectric transformer 13 and the capacitor 3. When the switch 4 is closed, the output voltage of the piezoelectric transformer 13 is After being rectified by a general rectifier circuit including two diodes 15 and 16, the discharge capacitor 3 is charged as electric energy for discharging the discharge tube 4. On the other hand, when the switch 4 is opened and the output voltage of the piezoelectric transformer 13 is applied to the discharge tube 4, the discharge voltage is triggered by the electric energy charged in the discharge capacitor 3 with the applied voltage as a trigger. Tube 4 emits a flash.
[0022]
In the strobe device of this embodiment having such a configuration, when the switch 14 is closed and the discharge capacitor 3 is being charged, the output load is heavy on the output side (output terminal) of the piezoelectric transformer 13. High voltage does not appear because of (large). On the other hand, when the switch 14 is switched to the open state, the output load on the output side of the piezoelectric transformer 13 is reduced unlike the case where the switch 14 is in the closed state. High voltage can be automatically generated.
[0023]
As described above, in the present embodiment, by focusing on the characteristic of the piezoelectric transformer element that the step-up ratio (output voltage) changes according to the size of the load, the single piezoelectric transformer 13 has two purposes as described above. (Charging of the discharge capacitor 3 and discharge trigger of the discharge tube 4). However, this method of use is peculiar to the conventional winding transformer whose step-up ratio is fixed in advance. Further, the strobe device shown in FIG. 1 employs a circuit configuration in which one set of booster circuits is shared for the two purposes described above, so that compared with the circuit configuration of the strobe device shown in FIG. The circuit and the piezoelectric transformer can be omitted one by one, the required number of electronic devices can be reduced, and the circuit configuration can be simplified. Can be made more compact.
[0024]
Therefore, according to this embodiment, it is possible to realize a strobe device excellent in space saving with a simple circuit configuration, and it is suitable to be adopted as a strobe device for a camera built in or externally attached to various cameras. . In this case, the operation of the switch 14 may be operated according to the shutter operation of the camera.
[0025]
<First Modification of First Embodiment>
Next, Modified Example 1 based on the strobe device according to the above-described first embodiment will be described. In the following description, the same configuration as that of the first embodiment will not be described repeatedly, and will be described focusing on the characteristic portions of this modified example.
[0026]
FIG. 2 is a block diagram illustrating a circuit configuration of a strobe device according to a first modification of the first embodiment. The circuit configuration illustrated in FIG. 1 is different from the configuration illustrated in FIG. Zo) 17 is further provided.
[0027]
In the strobe device shown in FIG. 2, the switch 14A is a switch or a switching element that operates at the same timing as the switch 14, but as shown in the figure, the switch connects the output of the piezoelectric transformer 13 to the discharge capacitor 3. It can be switched to either the first line to be connected or the second line to be connected to the trigger line of the discharge tube 4.
[0028]
The load 17 provided in parallel on the output side of the piezoelectric transformer 13 is a high-impedance load resistance, and in this modification, when the switch 14A is switched between the first and second lines, the piezoelectric transformer 13 Are connected to prevent an excessively high voltage from being generated in the piezoelectric transformer 13 when the output of the piezoelectric transformer 13 is completely opened, and as a result, the piezoelectric transformer is damaged.
[0029]
According to the first modification of such a configuration, the same effect as the strobe device shown in FIG. 1 can be obtained.
[0030]
<Modification 2 of the first embodiment>
Next, a modified example 2 based on the strobe device according to the above-described first embodiment will be described. In the following description, the same configuration as that of the first embodiment will not be described repeatedly, and will be described focusing on the characteristic portions of this modified example.
[0031]
FIG. 3 is a block diagram showing a circuit configuration of a strobe device according to a second modification of the first embodiment. The circuit configuration shown in FIG. 1 is different from the first embodiment in that switches 14B and 14C are provided instead of switch 14. , A load (Zo) 17.
[0032]
In the strobe device shown in FIG. 3, the switch 14B is provided in series with the first line connecting the output of the piezoelectric transformer 13 to the discharge capacitor 3, and the switch 14C connects the output of the piezoelectric transformer 13 to the trigger of the discharge tube 4. A switch or a switching element provided in series with a second line connected to the line.
[0033]
The switch 14B and the switch 14C operate at the same timing as the switch 14 shown in FIG. 1 so that when one of them is open, the other takes a closed state, so that the output of the piezoelectric transformer 13 is changed to the first or the first. It can be switched to any of the two lines.
[0034]
The load 17 provided in parallel on the output side of the piezoelectric transformer 13 is a high-impedance load resistor provided for the same reason as the above-described first modification (FIG. 2).
[0035]
According to the second modification of such a configuration, the same effect as that of the strobe device shown in FIG. 1 can be obtained.
[0036]
In the following embodiments, for convenience of explanation, one switch that performs the same switching operation as the switch 14A will be described as an example. However, a circuit that uses the two switches 14B and 14C described in the present modification will be described. A configuration may be adopted.
[0037]
[Second embodiment]
Next, a second embodiment based on the strobe device according to the first embodiment and its modification will be described. In the following description, the same configuration as that of the first embodiment will not be described repeatedly, and will be described focusing on the characteristic portions of the present embodiment.
[0038]
FIG. 4 is a block diagram illustrating a circuit configuration of a strobe device according to the second embodiment.
[0039]
In the strobe device shown in the figure, the oscillation circuit 11A is capable of outputting a plurality of types of oscillation signals having different frequencies, and is driven in accordance with (in conjunction with) the operation of a switch 14D provided in place of the switch 14. The frequency of the oscillation signal to be output to the circuit 12 is changed.
[0040]
In the present embodiment, the connection and operation of the switch 14D on the output side of the piezoelectric transformer element 13 are the same as the operation of the switch 14A described in the first modification (FIG. 2), and are the same as those in the first modification. Therefore, a high-impedance load 17 is provided in parallel with the output side of the piezoelectric transformer 13 in order to consider the occurrence of an open state due to the provision of the switch 14D.
[0041]
The circuit configuration of the oscillation circuit 11A that changes the frequency of the oscillation signal to be output according to an input signal from the outside is, for example, when a voltage-controlled oscillation circuit (VCO) is employed as the oscillation circuit 11A, It is sufficient to add a circuit for switching the magnitude of the control voltage to be input to the switch. Alternatively, when a CR oscillation circuit is adopted as the oscillation circuit 11A, it may be realized by adding a circuit for switching the value of the capacitance of C (capacitor) and / or the value of R (resistance) constituting the circuit.
[0042]
Here, the reason why the frequency of the oscillation signal output from the oscillation circuit 11A is changed according to the operation of the switch 14D will be described with reference to the circuit in FIG.
[0043]
FIG. 5 is a diagram illustrating the relationship between the output voltage of the piezoelectric transformer 13 that changes according to the size of the load and the frequency of the oscillation signal.
[0044]
When the piezoelectric transformer 13 is driven by the drive circuit 12, the load is large (heavy) when charging the discharge capacitor 3 with the switch 14A connected to the first line, while the switch 14A is connected to the first line. When used for triggering the discharge tube 4 in a state where the two lines are connected, the resonance point of the piezoelectric transformer 13 generally differs because the load is small (light).
[0045]
In such operation characteristics, when the power supply voltage of the drive circuit 12 is sufficiently higher than the charge voltage of the discharge capacitor 3, the frequency of the oscillation signal output from the oscillation circuit 11 becomes as shown in FIG. In the power supply voltage, a high frequency for triggering may be set in advance to a predetermined frequency obtained at the output side of the piezoelectric transformer 13.
[0046]
On the other hand, when the power supply voltage of the drive circuit 12 is low, when the oscillation circuit 11 outputs an oscillation signal having the same frequency as the predetermined frequency, the output voltage of the piezoelectric transformer 13 is applied to the charge voltage of the discharge capacitor 3. Can only obtain an insufficient voltage. In this case, in order to generate a sufficient voltage in the piezoelectric transformer 13 as the charging voltage, the frequency may be set near the resonance point during charging as shown in FIG. 5B. Even if the connection of the switch 14A is switched to the second line for triggering at the same frequency, a necessary and sufficient high voltage for triggering cannot be obtained.
[0047]
Therefore, in the present embodiment, as shown in FIG. 5C, the frequency of the oscillation signal output from the oscillation circuit 11A is triggered from the low charging frequency in response to (in conjunction with) the switching operation of the switch 14D. By switching to a higher frequency, the piezoelectric transformer 13 always generates an optimum output voltage.
[0048]
According to the second embodiment having such a circuit configuration, the same effect as that of the strobe device shown in FIG. 1 can be obtained, and further, even when charging or triggering is performed. Thus, an optimum output voltage can be generated in the piezoelectric transformer 13.
[0049]
[Third Embodiment]
Next, a description will be given of the above-described first embodiment and its modification, and a third embodiment based on the strobe device according to the second embodiment. In the following description, the same components as those of the embodiment and the modified example will not be described repeatedly, and will be described focusing on the characteristic portions of the present embodiment.
[0050]
FIG. 6 is a block diagram showing a circuit configuration of a strobe device according to the third embodiment.
[0051]
The strobe device shown in the figure has the oscillation circuit 11A described in the second embodiment instead of the oscillation circuit 11 based on the circuit configuration of the first modification (FIG. 2) of the first embodiment. In addition, a charging voltage detection circuit 18 is newly provided.
[0052]
The charging voltage detection circuit 18 is provided at the subsequent stage of the rectifier circuit including the diodes 15 and 16, detects the charging voltage of the discharge capacitor 3, and, when the detected charging voltage reaches a predetermined level, outputs a signal indicating that. The signal is transmitted to the oscillation circuit 11A. Then, the oscillation circuit 11A that has obtained this signal switches the charging frequency that has been output up to that time to the predetermined trigger frequency. At this time, the state in which the switch 14A is connected to the first line (the charging side of the discharge capacitor 3) continues, but the charges charged in the discharge capacitor 3 include the diodes 15 and 16 forming a rectifier circuit. Therefore, it is not discharged until a trigger is applied by the switch.
[0053]
According to the third embodiment having such a circuit configuration, the same effect as that of the strobe device shown in FIG. 1 can be obtained, and even when charging or triggering is performed. Thus, an optimum output voltage can be generated in the piezoelectric transformer 13.
[0054]
[Fourth embodiment]
Next, a fourth embodiment based on the strobe device according to the first embodiment will be described. In the following description, the same components as those of the embodiment and the modified example will not be described repeatedly, and will be described focusing on the characteristic portions of the present embodiment.
[0055]
FIG. 8 is a block diagram illustrating a circuit configuration of a flash device according to the fourth embodiment.
[0056]
The strobe device shown in the figure is based on the circuit configuration of the above-described first embodiment (FIG. 1), in which two discharge capacitors are connected in series, and a rectifier diode is connected to the minus side of the series capacitor without being grounded. Above, the connection point between the capacitors is electrically grounded.
[0057]
With this configuration, only half-wave rectification can be performed in the first embodiment, but full-wave rectification can be performed in the present embodiment. Therefore, the potential difference applied to the flash discharge tube 807 is equal to the potential difference in the first embodiment. Twice as large as
[0058]
Generally, a voltage of about 300 V must be applied to both ends of the flash discharge tube. However, in the device corresponding to the first embodiment, an output of AC 300 V or more is possible so that the charging voltage of the charging capacitor becomes about +300 V. Must use a suitable piezoelectric transformer. On the other hand, in the present embodiment, the circuit can be configured so that a voltage of about ± 150 V is applied to both ends of the flash discharge tube, the capability required for the piezoelectric transformer is reduced, and the size can be reduced in size. In addition, since a charge capacitor having a small withstand voltage can be used, a small and inexpensive circuit can be realized.
[0059]
【The invention's effect】
According to the present invention described above, it is possible to provide a strobe device having a simple circuit configuration and excellent space saving.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a circuit configuration of a strobe device according to a first embodiment.
FIG. 2 is a block diagram illustrating a circuit configuration of a strobe device according to a first modification of the first embodiment.
FIG. 3 is a block diagram illustrating a circuit configuration of a strobe device according to a second modification of the first embodiment.
FIG. 4 is a block diagram illustrating a circuit configuration of a strobe device according to a second embodiment.
FIG. 5 is a diagram illustrating the relationship between the output voltage of the piezoelectric transformer 13 that changes according to the size of the load and the frequency of the oscillation signal.
FIG. 6 is a block diagram illustrating a circuit configuration of a strobe device according to a third embodiment.
FIG. 7 is a diagram showing a circuit configuration of a strobe device including two sets of piezoelectric transformer inverter circuits previously proposed by the present applicant.
FIG. 8 is a block diagram illustrating a circuit configuration of a strobe device according to a fourth embodiment.

Claims (8)

A discharge tube for flash, a capacitor for storing electric energy for causing the discharge tube to emit light, a charging circuit for charging the capacitor with electric energy, and a trigger circuit for generating a high voltage signal for promoting discharge of the discharge tube are provided. A strobe device,
A boosting circuit including one piezoelectric transformer, which is commonly used as boosting means of the charging circuit and the trigger circuit;
Switching means for switching the booster circuit for the charging circuit or the trigger circuit so as to apply the output voltage of the piezoelectric transformer to the capacitor or the discharge tube;
A strobe device comprising: The switching means,
The strobe device according to claim 1, wherein at least one switch or switching element is provided in series with a line connecting the output of the piezoelectric transformer and the capacitor. The switching means,
The strobe light according to claim 1, wherein the strobe is at least one switch or switching element that switches an output of the piezoelectric transformer to a first line connected to the capacitor or a second line connected to a trigger line of the discharge tube. apparatus. When the switch or the switching element performs a switching operation, a high-impedance load is connected in parallel with the output of the piezoelectric transformer in order to prevent the output of the piezoelectric transformer from being completely opened. The strobe device according to claim 3, wherein: In the charging circuit and the trigger circuit, the oscillating circuit of the piezoelectric transformer can output a plurality of types of oscillating signals having different frequencies, and according to a switching operation by the switching unit, outputs any one of the oscillating signals. The strobe device according to any one of claims 1 to 4, wherein the strobe device outputs. Further, a charge voltage detection circuit for detecting a charge voltage of the capacitor,
In the charging circuit and the trigger circuit, the oscillation circuit of the piezoelectric transformer can output a plurality of types of oscillation signals having different frequencies, and any one of the oscillation signals can be output according to the output signal of the charging voltage detection circuit. The strobe device according to any one of claims 1 to 4, wherein the strobe device outputs the information. 7. The strobe device according to claim 1, wherein the strobe device is a strobe device for a camera which is built in or external to a camera, and wherein the switching means operates in response to a shutter operation of the camera. The strobe device according to any one of the above. The capacitor is a capacitor in which two capacitors connected in series are connected in parallel with the flash discharge tube and a rectifier circuit in the charging circuit, and the contacts of the two capacitors are electrically grounded. The strobe device according to claim 1, wherein:

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