JP4607376B2 - Strobe device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a strobe device, for example, a strobe device suitable for being built in or externally attached to various cameras.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, so-called strobe devices that instantaneously illuminate a subject at the time of shooting have been widely used in cameras that take silver halide photographs or digital cameras that take images using an image sensor.
[0003]
As an example of such a strobe device, the applicant of the present application should realize a small and light strobe device with a simple device configuration in Japanese Patent Application No. 2000-395929 (not disclosed at the time of filing this application). 3 proposes the strobe device shown in FIG.
[0004]
That is, the strobe device shown in FIG. 3 is roughly divided into a flash discharge tube (for example, a xenon discharge tube) 4, a discharge capacitor 3 for storing electric energy for causing the discharge tube 4 to emit light, and charging for charging the discharge capacitor 3 with electric energy. The circuit 1 and the trigger circuit 2 that generates a high voltage signal that prompts discharge of the discharge tube 4 are configured.
[0005]
Such a circuit includes a booster circuit (11, 12, 13) including one piezoelectric transformer 13 that is shared as a boosting unit for the charging circuit 1 and the trigger circuit 2. In the booster circuit, the piezoelectric transformer 13 is provided. Secondary electrodes 6 and 7 are provided at two different distances (L 1 and L 2) from the primary electrode 5 provided in the primary side region, respectively, in the secondary side region of the piezoelectric transformer 13. The charging operation of the discharge capacitor 3 and the triggering operation of the discharge tube 4 are realized by appropriately turning on and off the switch 14B connected to the charging line in the side region and the switch 14C connected to the trigger line. .
[0006]
[Problems to be solved by the invention]
According to the circuit configuration described above, the piezoelectric transformer 13 provided in one booster circuit uses the two secondary electrodes for the charging circuit and the trigger circuit, so that only one booster circuit is charged. And a trigger function can be achieved, and a strobe device excellent in space saving can be realized with a simple device configuration.
[0007]
However, in the above circuit configuration, the switch 14B and the switch 14C connected to the secondary electrodes 6 and 7 of the piezoelectric transformer 13 have an alternating high voltage (several numbers) output from the piezoelectric transformer 13 according to the switching operation. Therefore, a high-breakdown-voltage switching element that can withstand the AC high voltage must be employed.
[0008]
However, a high-breakdown-voltage switching element that can be used at the time of filing this application to turn on / off the output voltage of the piezoelectric transformer, such as the switch 14B and the switch 14C, is expensive and has a relatively large external size. The circuit configuration shown in FIG. 3 is not sufficient to meet the demand for further miniaturization of the strobe device, which hinders the miniaturization of the overall shape.
[0009]
Accordingly, an object of the present invention is to provide a strobe device having a simple and low-cost device configuration and excellent in space saving.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a strobe device according to the present invention is characterized by the following configuration.
[0011]
That is, a flash discharge tube (4), a capacitor (3) for storing electric energy for emitting light from the discharge tube, and a charging circuit (11, 12, 13A, 15, 16, 18 for charging the capacitor with electric energy). ), A trigger circuit (11, 12, 13A, 19, 19A, 25) for generating a high voltage signal that promotes discharge of the discharge tube, and a boosting means for the charging circuit and the trigger circuit, A strobe device comprising a booster circuit (11, 12, 13A) including one piezoelectric transformer,
Switching means (20) such as a switch element for separating the capacitor and the discharge tube from a reference potential (ground potential) common to the charging circuit and the trigger circuit according to the operation of the trigger circuit. And
[0012]
According to such a device configuration, since the charging circuit and the trigger circuit are in a floating state separated from the common reference potential according to the operation of the trigger circuit, the withstand voltage characteristic required for the switching means is several hundred volts. The degree is sufficient. Therefore, unlike the switches 14B and 14C described above with reference to FIG. 3, an AC high voltage of about several kV is not applied across the switches, and the switching means is a low-cost and small-sized member. (Switch element) can be employed. In other words, it is possible to provide a strobe device that is simple and low-cost and that is more space-saving.
[0013]
In a preferred embodiment, the apparatus further comprises second switching means (21) for separating at least the capacitor and the discharge tube from the secondary electrode of the piezoelectric transformer according to the operation of the trigger circuit.
The capacitor and the discharge tube form a closed circuit in a state where they are separated from the reference potential and the secondary electrode of the piezoelectric transformer.
[0014]
A strobe device having any of the above configurations is suitable for use in a camera that is built in or externally attached to various cameras. In that case, the trigger circuit operates according to the shutter operation of the camera. good.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a strobe device according to the present invention will be described in detail with reference to the drawings.
[0016]
[First Embodiment]
FIG. 1 is a block diagram showing a circuit configuration of the strobe device according to the first embodiment.
[0017]
The strobe device shown in FIG. 1 is roughly divided into a flash discharge tube (for example, a xenon discharge tube) 4, a discharge capacitor 3 for storing electrical energy for causing the discharge tube 4 to emit light, a charging circuit for charging the discharge capacitor 3 with electrical energy, In addition, it is constituted by a trigger circuit that generates a high voltage signal that prompts discharge of the discharge tube 4.
[0018]
The charging circuit and the trigger circuit are provided with a set of boosting circuits including an oscillation circuit 11, a driving circuit 12, and a piezoelectric transformer 13A as a common boosting unit. The driving circuit 12 is a predetermined output from the oscillation circuit 11. The piezoelectric transformer 13A is driven in accordance with the frequency oscillation signal. Here, the piezoelectric transformer 13A is a Rosen-type piezoelectric transformer element.
[0019]
Incidentally, as for the individual circuit configurations of the oscillation circuit 11 and the drive circuit 12, it is sufficient to use a general device at present, and therefore a detailed description in this embodiment is omitted.
[0020]
As shown in FIG. 1, the discharge capacitor 3, the discharge tube 4, and the anode terminal of the rectifying diode 16 are connected in parallel. When the switch (switch element) 20 is closed, the reference potential (ground voltage) is set. ) To ground.
[0021]
Here, the switch (switch element) 20 can employ a semiconductor element such as a transistor having a withstand voltage characteristic of about several hundred volts, an FET (field effect transistor), an IGBT (insulated gate bipolar transistor), and the like. The operation state (closed state / open state) is switched by the trigger control circuit 19.
[0022]
In the present embodiment, the charging circuit includes the oscillation circuit 11, the drive circuit 12, the piezoelectric transformer 13A, the rectifier circuit 18, the discharge capacitor 3, and the switch 20. When the switch 20 is in the closed state, the output of the piezoelectric transformer 13A. The voltage is rectified by a rectifier circuit 18 having a general configuration including two diodes 15 and 16, and then charged to the discharge capacitor 3 as electric energy for discharging the discharge tube 4.
[0023]
On the other hand, the trigger circuit includes the oscillation circuit 11, the drive circuit 12, the piezoelectric transformer 13A, the trigger control circuit 19, the discharge tube 4, the switch 20, and the trigger line 25. The switch 20 switches from the closed state to the open state. Accordingly, the discharge capacitor 3 and the discharge tube 4 are in a floating state separated from the ground potential.
[0024]
In such a floating state, the load connected to the secondary electrode of the piezoelectric transformer 13A is in a high impedance state as compared with the case where the switch 20 is in the closed state. As the step-up ratio of the piezoelectric transformer 13A changes, a high voltage that can be a trigger signal for prompting the discharge tube 4 to flash is applied to the trigger line 25 connected to the trigger terminal of the discharge tube 4. As a trigger, the discharge tube 4 emits flash light by the electric energy charged in the discharge capacitor 3.
[0025]
In the present embodiment, the trigger control circuit 19 that controls the operating state of the switch 20 operates according to a trigger start signal input from the outside. In a preferred embodiment, the strobe device according to the present embodiment is When employed as a strobe device for a camera built in or externally attached to various cameras, the trigger control circuit 19 (switch 20) may be operated in accordance with the shutter operation of the camera.
[0026]
According to the above-described embodiment, the discharge capacitor 3 and the discharge tube 4 are in a floating state separated from the common reference potential (ground potential) by the switch 20 according to the operation of the trigger circuit. A required withstand voltage characteristic is about several hundred volts. Therefore, unlike the switches 14B and 14C described above with reference to FIG. 3, an AC high voltage of about several kV is not applied across the switches, and the switch 20 is a low-cost and small-sized member ( Switch element) can be employed. In other words, it is possible to provide a strobe device that is simple and low-cost and that is more space-saving.
[0027]
[Second Embodiment]
Next, a second embodiment based on the strobe device according to the first embodiment described above will be described. In the following description, the description similar to that of the first embodiment will be omitted, and the description will focus on the characteristic part of the present embodiment.
[0028]
In the first embodiment (FIG. 1) described above, the discharge tube 4 is triggered by the switch 20 that disconnects the discharge capacitor 3 and the discharge tube 4 from the ground potential. For this reason, when the switching element employed as the switch 20 does not match the entire control circuit, the voltage (trigger signal) applied to the trigger line 25 in response to the switch 20 being opened is discharged. It is also assumed that the light emission of the discharge tube 4 cannot be triggered by not reaching a predetermined high voltage necessary and sufficient to promote the light emission of the tube 4. Therefore, in the present embodiment, it is a further object to make the discharge tube 4 emit light more reliably based on the strobe device according to the first embodiment.
[0029]
FIG. 2 is a block diagram showing a circuit configuration of the strobe device according to the second embodiment.
[0030]
The circuit configuration of the strobe device shown in FIG. 2 is further between the secondary side electrode of the piezoelectric transformer 13A and the input stage of the rectifier circuit 18 as compared with the circuit configuration of the strobe device described above with reference to FIG. The difference is that a switch (switch element) 21 connected in series is provided.
[0031]
In the present embodiment, the switch (switch element) 21 may be a semiconductor element such as a transistor, FET, or IGBT, as with the switch 20, and is operated by the trigger control circuit 19A (closed state / open state). Is switched.
[0032]
Also in the present embodiment, the trigger control circuit 19A that controls the operating state of the switches 20 and 21 operates in accordance with a trigger start signal input from the outside. In a preferred embodiment, the strobe according to the present embodiment is used. When the device is employed as a strobe device for a camera built in or externally attached to various cameras, the trigger control circuit 19A (switches 20 and 21) may be operated according to the shutter operation of the camera.
[0033]
More specifically, when starting the charging of the discharge capacitor 3, the trigger control circuit 19A switches the switches 20 and 21 that are both open to the closed state in the order of the switch 21 and then the switch 20. . When triggering the discharge tube 4, the trigger control circuit 19 </ b> A switches the switches 20 and 21, both of which are closed, to the open state in the order of the switch 20 and then the switch 21.
[0034]
According to the present embodiment described above, in the floating state in which the discharge capacitor 3 and the discharge tube 4 are separated from the common reference potential (ground potential) by the switch 20 according to the operation of the trigger circuit, the discharge capacitor 3 and the discharge capacitor 3 are discharged. The tube 4 is further separated from the secondary electrode of the piezoelectric transformer 13A by the switch 21.
[0035]
That is, the discharge capacitor 3 and the discharge tube 4 form a closed circuit, and the influence of the stray capacitance of the circuit connected to the secondary side of the piezoelectric transformer 13A is eliminated, and the secondary of the piezoelectric transformer 13A is eliminated. Since a higher impedance state can be realized in the side electrode as compared with the first embodiment, a predetermined high voltage necessary and sufficient to promote the light emission of the discharge tube 4 can be applied to the trigger line 25. As a result, the discharge tube 4 can emit light more reliably.
[0036]
As described above, according to the present embodiment, in addition to the same effects as those of the first embodiment, the discharge tube 4 can emit light more reliably.
[0037]
In this embodiment, the switch 21 is connected in series to the secondary electrode of the piezoelectric transformer 13A. However, the present invention is not limited to this circuit configuration and is similar to the switch 14C in the circuit shown in FIG. Further, a switch may be further provided on the trigger line, and the switch and the switch 21 may be interlocked (in this case, when one is open, the other is closed).
[0038]
【The invention's effect】
According to the present invention described above, it is possible to provide a strobe device that has a simple and low-cost device configuration and is more space-saving.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a circuit configuration of a strobe device according to a first embodiment.
FIG. 2 is a block diagram showing a circuit configuration of a strobe device according to a second embodiment.
FIG. 3 is a diagram showing a circuit configuration of a strobe device previously proposed by the present applicant.
[Explanation of symbols]
1: charging circuit,
2: Trigger circuit,
3: Discharge capacitor,
4: discharge tube,
5: primary electrode,
6, 7: Secondary electrode,
11: Oscillator circuit,
12: drive circuit,
13, 13A: Piezoelectric transformer,
14B, 14C, 20, 21: switch,
15, 16: Rectifier diode,
18: Rectifier circuit,
19, 19A: trigger control circuit,
25: Trigger line,

Claims (3)

A discharge tube for flashing, a capacitor for storing electrical energy for causing the discharge tube to emit light, a charging circuit for charging the capacitor with electrical energy, a trigger circuit for generating a high voltage signal for encouraging discharge of the discharge tube, A strobe device comprising a charging circuit and a booster circuit including one piezoelectric transformer, which is shared as a booster for the trigger circuit,
A strobe device comprising switching means for separating the capacitor and the discharge tube from a reference potential common to the charging circuit and the trigger circuit according to the operation of the trigger circuit. Furthermore, according to the operation of the trigger circuit, the second switching means for separating at least the capacitor and the discharge tube from the secondary side electrode of the piezoelectric transformer,
2. The strobe device according to claim 1, wherein the capacitor and the discharge tube form a closed circuit in a state where the capacitor and the discharge tube are separated from the reference potential and the secondary electrode of the piezoelectric transformer, respectively. 3. The strobe device according to claim 1, wherein the strobe device is a camera strobe device built in or externally attached to the camera, and the trigger circuit operates in accordance with a shutter operation of the camera. Strobe device.

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