JP4105491B2 - Piezoelectric transformer and strobe device having the piezoelectric transformer - Google Patents

Description

【００７０】
上述したように、本実施形態に係るストロボ装置に採用可能な圧電トランス１３Ｂには、その分極方向に複数のバリエーションがあり、より具体的には、１次側領域を構成する第１及び第２の入力領域の分極方向と、２次側領域を構成する第１及び第２の出力領域の分極方向との組み合わせに応じて、［表１］に示すケースＩ乃至ＩＶの４つの場合が想定され、その個々のケースによって、ＳＷｄの好ましい接続状態も異なる。
【００７１】
即ち、ケースＩでは、圧電トランス１３Ｂにおいて、第１及び第２の入力領域が互いに同方向に分極され、且つ第１及び第２の出力領域は互いに異なる方向に分極されており、この場合に、ＳＷｄは、放電コンデンサ３を充電する充電状態では「Ｂ側」、放電管４にトリガを駆ける際には「Ａ側」に接続する必要がある。
【００７２】
また、ケースＩＩでは、圧電トランス１３Ｂにおいて、第１及び第２の入力領域が互いに異なる方向に分極され、且つ第１及び第２の出力領域は互いに異なる方向に分極されており、この場合に、ＳＷｄは、充電状態では「Ａ側」、トリガを駆ける際には「Ｂ側」に接続する必要がある。
【００７３】
また、ケースＩＩＩでは、圧電トランス１３Ｂにおいて、第１及び第２の入力領域が互いに同じ方向に分極され、且つ第１及び第２の出力領域は互いに同じ方向に分極されており、この場合に、ＳＷｄは、充電状態では「Ｂ側」、トリガを駆ける際には「Ａ側」に接続する必要がある。
【００７４】
そして、ケースＩＶでは、圧電トランス１３Ｂにおいて、第１及び第２の入力領域が互いに異なる方向に分極され、且つ第１及び第２の出力領域は互いに同じ方向に分極されており、この場合に、ＳＷｄは、充電状態では「Ａ側」、トリガを駆ける際には「Ｂ側」に接続する必要がある。
【００７５】
図６は、第２の実施形態に係るストロボ装置の動作を説明する図であり、図６（ａ）に示す第１共振モード（充電状態）、図６（ｂ）に示す第２共振モード（トリガ状態）のそれぞれの駆動状態における圧電トランス１３Ｂ内部の長手方向の応力分布と、その応力によって出力端子に発生する出力電圧（実効値）とを示している（尚、圧電トランス１３Ｂとしては、一例として、上述したケースＩを採用している）。
【００７６】
即ち、図６（ａ）に示す第１共振モードでは、充電コンデンサ３を充電すべく、圧電トランス１３Ｂが２λモードにて駆動されており、且つＳＷｄが「Ｂ側」に接続された状態において、２次側領域の出力電極２３からは、出力電圧Ｖ１を取り出すことができる。
【００７７】
そして、係る２λモードによる駆動が継続され、例えば充電コンデンサ３が所定の満充電状態に至ったことが不図示の回路にて検出された後、あるタイミングにおいて、放電管４にトリガを駆けるべく、発振回路１１から駆動回路１２に供給される発振信号の周波数が変更されることによって第２共振モード（この例ではλモード）となり、且つＳＷｄが「Ａ側」に切り替えられると、圧電トランス１３Ｂは、図６（ｂ）に示す状態を採る。これにより、２次側領域の出力電極２２からは、出力電圧Ｖ２を取り出すことができ、放電管４は、出力電圧Ｖ２がトリガラインを介して放電管４のトリガ端子（不図示）に印加されるのに応じて発光する。
【００７８】
尚、上記の例では、第２共振モードでは、圧電トランス１３Ｂをλモードにて駆動したが、これに限られるものではなく、λ／２モードにて駆動しても良い。
【００７９】
ここで、「発明が解決しようとする課題」に挙げた従来技術では、圧電トランス（圧電トランス素子）と外部との接続を容易にすべく、１次側領域をなす２種類（第１及び第２）の入力領域は、互いに逆方向に分極されていることが望ましいが、互いに異なる分極方向の場合には、当該２種類の入力領域の境界部分に分極時の応力歪みが発生するため、素子の強度に弱くなるという問題がある。
【００８０】
一方、圧電トランス１３Ｂの分極方向としては、上述した４つのケースがあり、本実施形態においても、上述したように１次側領域をなす２種類（第１及び第２）の入力領域の分極方向を、ケースＩＩまたはケースＩＶの如く互いに逆方向にすることも可能であるが、その場合、係る従来技術と同様な強度的な問題が生じることが予想される。
【００８１】
しかしながら、本実施形態では、圧電トランス１３Ｂを駆動するに際して、２種類の入力領域（即ち、２組み入力電極間）を上記の如くスイッチＳＷｄを適宜切り替えることが前提となるので、外部接続を容易にすべく当該２種類の入力領域を互いに逆方向に分極する必要は無い。即ち、本実施形態では、圧電トランス１３Ｂにおいて、１次側領域をなす２種類（第１及び第２）の入力領域の分極方向を、ケースＩまたはケースＩＩＩの如く同じ方向にすることにより、反対方向に分極する場合と比較して素子の強度に優れ、且つ製造時の分極工程も容易にすることができる。
【００８２】
このように、本実施形態では、図３に示す圧電トランス１３Ｂを、図４に示す回路構成のストロボ装置に採用することにより、出力電極２２，２３から得られる２種類の出力電圧Ｖ１，Ｖ２を、共振モードを適宜切り替えることによって使い分けるという本願特有の方法により、上述した本願出願人による従来のストロボ装置では必要であったスイッチ（スイッチング素子）を用いること無く、放電コンデンサ３への充電機能と、放電管４のトリガ機能とを適切に切り替えることを実現している。
【００８３】
即ち、本実施形態では、共振モードの切り替えに応じて、スイッチＳＷｄの接続状態が「Ａ側」または「Ｂ側」に切り替えられるが、ストロボ装置（図４）の回路構成においてＳＷｄが切り替える対象は、発振回路１１から出力される発振信号である。このため、上述した本願出願人による従来のストロボ装置において圧電トランスの２次側領域に接続されたスイッチ（スイッチング素子）とは異なり、スイッチＳＷｄ２は、数ｋＶ程度の交流高電圧に耐え得るような高耐圧のスイッチング素子である必要はなく、そのようなスイッチング素子と比較して廉価で小型のスイッチング素子を採用することができる。
【００８４】
従って、本実施形態に係る圧電トランス１３Ｂによれば、１次側領域内部における機械的な振動を促進することができるので、上述した第１の実施形態に係る圧電トランス１３Ａと比較して昇圧率に優れ、充電速度の迅速化を図ることができる。そして、このような特徴を有する圧電トランス１３Ｂを備えるストロボ装置（図４及び図５）によれば、シンプルな装置構成で、省スペース性に優れるストロボ装置を実現することができ、各種カメラに内蔵または外付けされるカメラ用のストロボ装置として採用して好適である。この場合、２種類の共振モードの切り替え動作と、ＳＷｄの切り替え動作とは、当該カメラのシャッター操作に応じて、例えば、発振回路１１が駆動回路１２に供給する発振信号の周波数を変更することによって実現すれば良い。
【００８５】
＜第２の実施形態の変形例＞
図７は、第２の実施形態の変形例に係るストロボ装置の回路構成を示すブロック図である。
【００８６】
図７に示すストロボ装置は、図４を参照して上述したストロボ装置と同様な構成を基本としており、本変形例において、充電回路１Ｂとトリガ回路２Ｂとは、発振回路１１、駆動回路１２、並びに圧電トランス１３Ｂからなる１組の昇圧回路を、共通の昇圧手段として備えているが、圧電トランス１３Ｂの２種類の入力領域のうち一方（同図に示す例では、第２の入力領域）に印加される入力電圧の位相を反転させるべく、反転回路１２３の代わりに、移相回路４１が設けられている点が異なる（尚、移相回路４１には一般的なものを採用可能であるため、詳細な説明は省略する）。
【００８７】
即ち、図５を参照して上述した回路構成では、スイッチング素子１２２−１及び１２２−２からなる第２のハーフブリッジ型駆動回路の前段にスイッチＳＷｄ及び反転回路１２３が設けられていたのに対して、本変形例では、図７に示す如く、駆動回路１２の後段に、スイッチＳＷ３と移相回路４１とが設けられ、そのＳＷ３の接続状態が「Ｂ側」の場合に、第２の入力領域（入力電極３２Ａ−３２Ｂ間）に印加される入力電圧の位相が反転される。
【００８８】
本変形例においても、ＳＷ３は、発振回路１１から駆動回路１２に供給される発振信号の周波数が変更されることによって共振モードが変更されるのに応じて、「Ａ側」または「Ｂ側」に切り替え可能であって、その好適な切り替え動作は、［表１］に示す如く圧電トランス１３Ｂの分極方向のバリエーションに応じて決定される。
【００８９】
このような本変形例によっても、上述した図４に示すストロボ装置と同様な効果を享受することができる。
【００９０】
【発明の効果】
上述した本発明によれば、スイッチ（スイッチング素子）を用いること無くコンデンサへの充電機能と、放電管のトリガ機能とを切り替えると共に、充電回路とトリガ回路とで共通の昇圧手段として共用可能な、昇圧率に優れる圧電トランス及びその圧電トランスを備えるストロボ装置の提供が実現する。
【図面の簡単な説明】
【図１】第１の実施形態に係る圧電トランスを示す図であり、図１（ａ）は、その圧電トランスの斜視図であり、図１（ｂ）は、図１（ａ）に示す圧電トランスを手前から見た正面図である。
【図２】第１の実施形態に係るストロボ装置の回路構成を示すブロック図である。
【図３】第２の実施形態に係る圧電トランスを示す図であり、図３（ａ）は、その圧電トランスの斜視図であり、図３（ｂ）は、図３（ａ）に示す圧電トランスを手前から見た正面図である。
【図４】第２の実施形態に係るストロボ装置の回路構成を示すブロック図である。
【図５】第２の実施形態に係るストロボ装置において、圧電トランス１３Ｂの２種類の入力電極（第１及び第２の入力領域）に印加する入力電圧を、２種類の共振モードの切り替えに応じて切り替え可能とする駆動回路の回路構成を例示する図である。
【図６】第２の実施形態に係るストロボ装置の動作を説明する図である。
【図７】第２の実施形態の変形例に係るストロボ装置の回路構成を示すブロック図である。
【符号の説明】
１，１Ａ，１Ｂ：充電回路，
２，２Ａ，２Ｂ：トリガ回路，
３：放電コンデンサ，
４：放電管，
１１：発振回路，
１２：駆動回路，
１３，１３Ａ，１３Ｂ：圧電トランス，
１５，１６：整流用ダイオード，
２１Ａ，２１Ｂ，２５Ａ，２５Ｂ：入力電極，
２２：出力電極（２次側層間接続導体），
２３：出力電極，
２４，２７，３６，３７，３８，３９：１次側層間接続導体，
２６Ａ，２６Ｂ，３３Ａ，３３Ｂ，３４Ａ，３４Ｂ：１次側内部電極，
２８：２次側内部電極，
４１：位相回路，
１２１−１，１２１−２，１２２−１，１２２−２：スイッチング素子，
１２３：反転回路，
ＳＷ１〜ＳＷ３，ＳＷｄ：スイッチ（スイッチング素子）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a strobe device suitable for being built in or externally attached to various cameras, for example.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, so-called strobe devices that 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 disclosed in Japanese Patent Application No. 2000-395929 and Japanese Patent Application No. 2001-160983 accompanied by a domestic priority claim, a charging circuit that charges a discharge capacitor with electric energy, A strobe device including a trigger circuit that generates a high voltage signal that promotes discharge of a discharge tube, and includes a booster circuit including one piezoelectric transformer that is commonly used as a booster for a charging circuit and a trigger circuit, In the line connecting the output of the piezoelectric transformer and the discharge capacitor, a switch (or a switching element) is provided in series to apply the output voltage of the piezoelectric transformer to the discharge capacitor or the discharge tube. By turning on / off, the discharge capacitor charging operation and the discharge tube trigger operation can be performed. It has proposed the current technology.
[0004]
[Problems to be solved by the invention]
According to the above circuit configuration, the charging function and the trigger function can be achieved with only one booster circuit, and a strobe device excellent in space saving can be realized with a simple circuit configuration.
[0005]
However, in the above circuit configuration, an alternating high voltage (approximately several kV) output from the piezoelectric transformer is applied to the switch that switches between the charging operation of the discharge capacitor and the trigger operation of the discharge tube according to the switching operation. Therefore, a high-breakdown-voltage switching element that can withstand the AC high voltage must be employed.
[0006]
However, a high-breakdown-voltage switching element that can be adopted at the time of filing the application to turn on and off the output voltage of the piezoelectric transformer, such as such a switch, is expensive and has a relatively large outer size, so It is a factor that hinders downsizing, and it is still not enough to meet the demand for further downsizing of strobe devices.
[0007]
By the way, in the international publication number (republished patent) WO 97/28568, an element structure of a piezoelectric transformer (FIGS. 6 and 7 in the same publication) having two types of input electrodes and two types of output electrodes is proposed. However, the driving method is not disclosed.
[0008]
Japanese Patent Laid-Open No. 10-23753 proposes an element structure and a driving method of a piezoelectric transformer (FIGS. 1 and 2 of the same publication) having two types of input electrodes and one type of output electrode.
[0009]
Japanese Patent Laid-Open No. 2002-94139 discloses a piezoelectric transformer (FIGS. 1 and 7 in the same publication) having two types of input electrodes and one type of output electrodes. Techniques for applying an input voltage have been proposed.
[0010]
The present invention has been made in view of the problem in the case where both the charging function and the trigger function are achieved with only the above-described one booster circuit. The charging function to the capacitor without using a switch (switching element), and the discharge tube An object of the present invention is to provide a piezoelectric transformer having an excellent boosting ratio that can be used as a common boosting means between a charging circuit and a trigger circuit, and a strobe device including the piezoelectric transformer.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a piezoelectric transformer according to the present invention is characterized by the following configurations (herein, reference numerals in parentheses included in the following configurations are the present invention and specific examples thereof) This represents the correspondence with the second embodiment to be described later).
[0012]
That is, a piezoelectric transformer (13B) having a rectangular outer shape in which one side in the longitudinal direction forms a primary region and the other forms a secondary region, and at least two types of input electrodes are formed in the primary region. Because
At least two types of output electrodes (22, 23) are formed in the secondary region,
As the at least two types of input electrodes (31A, 31B, 32A, 32B), the same or different input voltages are applied to the primary region of the piezoelectric transformer, while the same or different input voltages are applied. There are various types of input electrodes,
The input voltage is applied to each of the two types of input electrodes, and selectively driven in the plurality of types of resonance modes, so that a plurality of types of different sizes can be obtained from the at least two types of output electrodes. The output voltage can be switched and taken out.
It is characterized by that.
[0013]
In the above configuration, preferably, the secondary region includes two types of electrodes: an electrode formed at an end portion thereof, and an intermediate electrode formed between the end portion and the primary side region. Output electrode is formed,
When the two types of output electrodes are driven in the first resonance mode, the first output voltage can be extracted from the first output electrode, but the second resonance mode is different from the first resonance mode. The second output voltage having a magnitude different from that of the first output voltage can be taken out from the second output electrode.
[0014]
For example, in the secondary region of the piezoelectric transformer, the polarization direction in the region between the primary region and the intermediate electrode and the polarization direction in the region between the intermediate electrode and the end of the secondary region are: It is preferable to configure them in opposite directions.
[0015]
In any of the above-described configurations, more preferably, in order to improve the step-up ratio and reduce the size of the piezoelectric transformer, each of the input electrodes in the primary region of the piezoelectric transformer has a plurality of internal electrodes. A laminated structure in which conductors are connected by a conductor is preferable.
[0016]
In order to achieve the same object, a strobe device according to the present invention includes a flash discharge tube, a capacitor that stores electrical energy that causes the discharge tube to emit light, and a charging circuit that charges the capacitor with electrical energy. A strobe device comprising: a trigger circuit that generates a high voltage signal that promotes discharge of the discharge tube; and a booster circuit that includes a single piezoelectric transformer that is commonly used as a booster for the charging circuit and the trigger circuit. And
A piezoelectric transformer in which the two types of input electrodes and the two types of output electrodes are formed;
In the booster circuit, by switching and taking out an output voltage from the two types of output electrodes in response to driving the piezoelectric transformer in the first or second resonance mode, the booster circuit is connected to the charging circuit. Or the trigger circuit can be switched.
[0017]
Preferably, in the step-up circuit, when the piezoelectric transformer is driven in the first resonance mode, the first output voltage extracted from the first output electrode of the two types of output electrodes is used. While the capacitor is charged, the piezoelectric transformer is driven in the second resonance mode in response to the switching of the driving state from the first resonance mode to the second resonance mode. A trigger may be driven to the discharge tube by the second output voltage extracted from the two output electrodes.
[0018]
In a preferred embodiment, the booster circuit preferably includes switching means (SW1 to SW3, SWd) for switching input voltages applied to the two types of input electrodes of the piezoelectric transformer.
[0019]
In this case, for example, when the piezoelectric transformer is driven in the first resonance mode, the switching unit is configured such that the first and second input regions including the two types of input electrodes are in a vibration state in directions opposite to each other. While adopting the first switching state ("B side") driven in the (stress generation state), when driving in the second resonance mode, the first and second input regions are in the same direction. It is preferable to adopt the second switching state “A side” driven in the vibration state.
[0020]
For example, in the booster circuit,
In the primary region of the piezoelectric transformer, the at least two types of input electrodes are polarized in the same direction,
In the secondary region of the piezoelectric transformer, the polarization direction in the region between the primary region and the intermediate electrode is opposite to the polarization direction in the region between the intermediate electrode and the end of the secondary region. If the direction is
The switching means adopts the first switching state in which input voltages having opposite polarities are applied to the first and second input regions when the piezoelectric transformer is driven in the first resonance mode. Thus, when driven in the second resonance mode, the second switching state in which input voltages having the same polarity are applied to the first and second input regions may be employed.
[0021]
Also, in the strobe device having any of the above configurations, the booster circuit is
While driving the piezoelectric transformer in a two-wavelength mode to charge the capacitor in the first resonance mode,
In order to drive the discharge tube in the second resonance mode, the piezoelectric transformer may be driven in a half wavelength mode or a one wavelength mode.
[0022]
In a preferred embodiment, the strobe device is a strobe device for a camera built in or externally attached to the camera,
In the booster circuit, the first and second resonance modes may be switched according to a shutter operation of the camera.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a piezoelectric transformer and a strobe device having the piezoelectric transformer according to the present invention will be described in detail with reference to the drawings.
[0024]
[First Embodiment]
<Piezoelectric transformer>
FIG. 1 is a view showing a piezoelectric transformer according to the first embodiment, FIG. 1A is a perspective view of the piezoelectric transformer, and FIG. 1B is a piezoelectric view shown in FIG. It is the front view which looked at the transformer from this side.
[0025]
The piezoelectric transformer 13A shown in the figure is, for example, a rectangular shape having a longitudinal length L of 30 mm, and input electrodes 25A and 25B are formed in the primary region on the left side. The primary side region as a step-up transformer is formed.
[0026]
As shown in FIG. 1A, an input electrode 25A and an input electrode 25B (not shown) that are opposed to each other in the vertical direction are formed in the primary region. In addition, a plurality of internal electrodes 26A and 26B are alternately stacked inside the primary side region in order to increase the step-up ratio, and the interlayer connection conductor 27 provided on the side surface includes the inside of the primary side region. Are connected to an input electrode 25B (not shown). A plurality of internal electrodes 26B in the primary side region are connected to the interlayer connection conductor 24 provided on the other side surface, and are also connected to the input electrode 25A.
[0027]
Also, in the piezoelectric transformer 13A, an output electrode 23 is formed on one surface (end surface) in the longitudinal direction of the piezoelectric transformer 13A among the six surfaces constituting the outer shape. Between the side regions (in the present embodiment, as an example, an intermediate position of L / 4 from the output electrode 23 in the longitudinal direction), as an example, a plurality of internal electrodes 28 are interlayer connection conductors that also function as output electrodes ( Hereinafter, it may be referred to as “output electrode”) 22.
[0028]
Incidentally, in the primary region of the piezoelectric transformer 13A, a plurality of internal electrodes 26A and 26B are connected to each other outside the primary region by means of interlayer connection conductors 24 and 27 as shown in FIG. However, the present invention is not limited to this, and a laminated structure in which every other layer is connected by an interlayer connection conductor formed inside the primary region may be used.
[0029]
Further, in the present embodiment, the shape of the interlayer connection conductor 22 is not limited to this, and may be, for example, a shape surrounding two opposing surfaces (side surfaces).
[0030]
Also, the output electrode 23 is not formed on the end surface of the secondary region, but a plurality of internal electrodes formed inside the secondary region near the end surface are formed inside or outside the secondary region. Alternatively, a laminated structure connected by the interlayer connection conductors may be adopted. When the interlayer connection conductor is formed outside the secondary side region, it is not always necessary to provide the output electrode 23 having the shape as shown in FIG. The device itself may be used as an output electrode.
[0031]
By driving the piezoelectric transformer 13A having such a structure by the drive circuit 12 in the strobe device shown in FIG. 2, output voltages of different magnitudes are generated from the interlayer connection conductor (output electrode) 22 and the output electrode 23. It can be taken out.
[0032]
That is, a combination in which “first resonance mode” is λ (wavelength) / 2 mode and “second resonance mode” is λ mode, or “first resonance mode” is 3λ / 2 mode, and “second resonance mode”. Paying attention to the combinations in which λ mode is used, when the input electrodes 25A and 25B are driven in the “first resonance mode”, the piezoelectric transformer 13A extracts the first output voltage from the first output electrode. On the other hand, when driven in the “second resonance mode” different from the first resonance mode, the second output voltage having a magnitude different from that of the first output voltage is supplied to the second output electrode. Can be taken out from.
[0033]
Further, the same operation as that of the piezoelectric transformer 13A described above can also be realized by combining the “first resonance mode” with the 5λ / 2 mode and the “second resonance mode” with the λ / 2 mode or λ mode.
[0034]
<Strobe device>
Next, a strobe device including the piezoelectric transformer 13A as a boosting unit will be described.
[0035]
FIG. 2 is a block diagram illustrating a circuit configuration of the strobe device according to the first embodiment.
[0036]
The strobe device shown in FIG. 2 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 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.
[0037]
The charging circuit 1 and the trigger circuit 2 include a set of boosting circuits including an oscillation circuit 11, a driving circuit 12, and a piezoelectric transformer 13 </ b> A as a common boosting unit. The driving circuit 12 outputs from the oscillation circuit 11. The piezoelectric transformer 13A is driven in accordance with the oscillation signal having a predetermined frequency.
[0038]
In this embodiment, the oscillation circuit 11 can output at least two types of oscillation signals having different frequencies as the predetermined frequency, and the drive circuit 12 can output the oscillation signal and a predetermined direct current applied from the outside. By supplying at least two types of drive signals having different frequencies to the input electrodes 25A and 25B based on the voltage, the piezoelectric transformer 13A has two different types of resonance modes ("first resonance mode" or "second resonance mode"). It can be driven in any of the “resonance modes”).
[0039]
In the charging circuit 1, the two diodes 15 and 16 constitute a general rectifier circuit, which outputs an output when the piezoelectric transformer 13 </ b> A is driven in the “first resonance mode”. An output voltage V1 output from the electrode 23 is applied. The discharge capacitor 3 charges the electric energy of the rectified voltage (DC voltage) for discharging the discharge tube 4.
[0040]
On the other hand, in the trigger circuit 2, when the piezoelectric transformer 13 </ b> A is driven in the “second resonance mode”, the output voltage V <b> 2 output from the interlayer connection conductor (output electrode) 22 is applied to the trigger terminal of the discharge tube 4. Is done. At this time, when the discharge capacitor 3 is in a predetermined charged state, the discharge capacitor 3 is charged using the applied voltage as a trigger in response to the output voltage V2 being applied to the trigger terminal of the discharge tube 4. The discharge tube 4 emits flash light by the electric energy.
[0041]
The individual circuit configurations of the rectifier circuit including the oscillation circuit 11, the drive circuit 12, and the rectifier diodes 15 and 16 may be a general device at present. Omitted.
[0042]
According to the strobe device of the present embodiment described above, when the piezoelectric transformer 13A is driven in the “first resonance mode”, the first of the two types of output electrodes 22 and 23 taken out from the first output electrode. While the discharge capacitor 3 is charged with the output voltage of 1, the piezoelectric transformer is switched in the “second resonance mode” in response to the resonance mode being switched from the “first resonance mode” to the “second resonance mode”. By driving 13A, a trigger can be driven to the discharge tube 4 by the second output voltage extracted from the second output electrode. That is, it is possible to switch between application of the first output voltage to the discharge capacitor 3 and application of the second output voltage to the trigger terminal of the discharge tube 4 in accordance with switching of the resonance mode of the piezoelectric transformer 13A. Yes, the charging circuit 1 and the trigger circuit 2 can share a set of booster circuits.
[0043]
As described above, in the present embodiment, by paying attention to the characteristics of the piezoelectric transformer element that the step-up ratio (output voltage) changes according to the size of the load, the single piezoelectric transformer can be used for two purposes (the discharge capacitor 3). And a set of booster circuits are used in a circuit configuration shared for the above two purposes. The configuration itself is basically the same as the strobe device by the applicant of the present invention described above in the “Prior Art”, but in this embodiment, the piezoelectric transformer 13A shown in FIG. 1 is replaced with the strobe having the circuit configuration shown in FIG. By adopting the device, the above-described conventional strobe device by the applicant of the present application described above by using a method peculiar to the present application in which two types of output voltages V1 and V2 obtained from the output electrodes 22 and 23 are selectively used by appropriately switching the resonance mode. Thus, it is possible to appropriately switch between the charging function of the discharge capacitor 3 and the trigger function of the discharge tube 4 without using a necessary switch (switching element).
[0044]
Therefore, according to the present embodiment, a strobe device excellent in space saving can be realized with a simple device configuration, and is suitable for use as a strobe device for a camera built in or externally attached to various cameras. . In this case, switching between the two types of resonance modes may be realized by changing the frequency of the oscillation signal supplied from the oscillation circuit 11 to the drive circuit 12 according to the shutter operation of the camera.
[0045]
[Second Embodiment]
Next, a second embodiment based on the piezoelectric transformer and 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.
[0046]
As described above, according to the piezoelectric transformer and the strobe device according to the first embodiment, two types of output voltages from the two types of output electrodes 22 and 23 of the piezoelectric transformer 13A are switched according to switching between the two types of resonance modes. Since V1 and V2 can be selectively obtained, a switch for switching between the charging function and the trigger function, which has been necessary in the past, can be omitted. However, as a result of further experiments by the present applicant, the structure of the piezoelectric transformer 13A having one (one set) input electrodes 25A and 25B in the primary side region (in the case where the primary side region is a single plate type structure). In the case of driving in which a vibration mode having a half wavelength (λ / 2) or more occurs in the primary region, the resonance mode for the charging function and the trigger function is 1 It was found that some mechanical vibrations were suppressed (cancelled) inside the secondary region. Suppression of mechanical vibration in the piezoelectric transformer indicates that the boosting performance is adversely affected.
[0047]
Therefore, the present embodiment aims to realize a piezoelectric transformer and a strobe device that are further excellent in boost ratio (boost ratio) compared to the first embodiment.
[0048]
<Piezoelectric transformer>
FIG. 3 is a diagram showing a piezoelectric transformer according to the second embodiment, FIG. 3A is a perspective view of the piezoelectric transformer, and FIG. 3B is a piezoelectric diagram shown in FIG. It is the front view which looked at the transformer from this side.
[0049]
As an example, the piezoelectric transformer 13B shown in the figure has a rectangular shape with a length L in the longitudinal direction of 30 mm. In the primary region on the left side thereof (length L / 2 in this embodiment), FIG. As shown in (a), two types (two sets) of input electrodes 31A and 31B and input electrodes 32A and 32B are formed at positions facing in the vertical direction. It forms the primary side area.
[0050]
That is, the two types of input electrodes 31A and 31B and the input electrodes 32A and 32B shown in the figure are different in size from each other, but the input electrode 25A described in the first embodiment is different from the input electrode 25A described in the first embodiment. The laminated structure is the same as that of the input electrode 25B (not shown).
[0051]
More specifically, a plurality of internal electrodes 33A and 33B are alternately stacked between the input electrodes 31A and 31B inside the primary side region, and the stacked structure is the same as that of the primary side region. Occupies about 1/2. A plurality of internal electrodes 33A in the primary side region are connected to the interlayer connection conductor 37 provided on the side surface, and are connected to the input electrode 31B (not shown), and provided on the other side surface. A plurality of internal electrodes 33B in the primary region are connected to the interlayer connection conductor 36, and are also connected to the input electrode 31A. Hereinafter, the region between the input electrodes 31A and 31B may be referred to as a “first input region”.
[0052]
In addition, a plurality of internal electrodes 34A and 34B are alternately stacked between the input electrodes 32A and 32B inside the primary side region, and the stacked structure is approximately 1 / of the primary side region. Occupies two. A plurality of internal electrodes 34A in the primary region are connected to the interlayer connection conductor 39 provided on the side surface, and are connected to the input electrode 32B (not shown), and provided on the other side surface. A plurality of internal electrodes 34B in the primary side region are connected to the interlayer connection conductor 38, and also connected to the input electrode 32A. Hereinafter, the region between the input electrodes 32A and 32B may be referred to as a “second input region”.
[0053]
The secondary side region of the piezoelectric transformer 13B has the same structure as the secondary side region of the piezoelectric transformer 13A in the first embodiment. However, in this embodiment, another structure is adopted as described above. (In this embodiment, for convenience of explanation, regarding the secondary side region of the piezoelectric transformer 13B, the space between the primary side region and the output electrode 22 is the “first output region”, and the output electrode 22 and the output region are output. The space between the electrodes 23 may be referred to as a “second output region”).
[0054]
In the present embodiment, the piezoelectric transformer 13B having such a structure is driven by the drive circuit 12 via the switch (SW) 1 and the switch 2 as shown in the strobe device shown in FIG. Output voltages of different magnitudes are taken out from the output electrode 22 existing as an intermediate electrode in the region and the output electrode 23 provided at the end of the secondary region.
[0055]
Even if the polarization direction of the primary region of the piezoelectric transformer 13B is the same in the first input region on the input electrodes 31A and 31B side and the second input region on the input electrodes 32A and 32B side, they are mutually On the other hand, the polarization direction of the secondary side region is different from the polarization direction in the region between the primary side region and the output electrode 22 that is the intermediate electrode, and between the intermediate electrode and the secondary side region. The polarization direction in the region between the output electrodes 23 provided at the end may be a direction facing each other or a direction opposite to each other. Therefore, the piezoelectric transformer 13B according to the present embodiment is assumed to have four polarization forms in consideration of the polarization directions of the primary side and secondary side regions. A driving method of the strobe device employing the transformer will be described later with reference to [Table 1].
[0056]
<Strobe device>
FIG. 4 is a block diagram showing a circuit configuration of the strobe device according to the second embodiment.
[0057]
The strobe device shown in FIG. 4 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 a charging circuit 1A for charging the discharge capacitor 3 with electric energy. And a trigger circuit 2A for generating a high voltage signal for prompting the discharge tube 4 to discharge.
[0058]
In the present embodiment, the charging circuit 1A and the trigger circuit 2A also include a set of boosting circuits including the oscillation circuit 11, the driving circuit 12, and the piezoelectric transformer 13B as a common boosting unit. The piezoelectric transformer 13B is driven in accordance with an oscillation signal having a predetermined frequency output from the oscillation circuit 11.
[0059]
Also in the present embodiment, the oscillation circuit 11 can output at least two types of oscillation signals having different frequencies as the predetermined frequency, and the drive circuit 12 includes an oscillation signal supplied from the oscillation circuit 11, By supplying at least two types of drive signals having different frequencies to the primary region of the piezoelectric transformer 13B based on a predetermined DC voltage applied from the outside, the piezoelectric transformer 13B has two different types of resonance modes. It can be driven by any one of ("first resonance mode" or "second resonance mode").
[0060]
However, in the present embodiment, the primary side region of the piezoelectric transformer 13B includes two types (two sets) of input electrodes 31A and 31B (first input region) and input electrodes 32A and 32B as shown in FIG. (Second input region) is provided, and the drive circuit 12 selectively drives the piezoelectric transformer 13B via the two types of input electrodes in a plurality of types of resonance modes as described below. There is a need to. Therefore, in this embodiment, in order to realize the selective driving operation of the piezoelectric transformer 13B, as schematically shown in FIG. 4, between the drive circuit 12 and the piezoelectric transformer 13B, switches (SW) 1 and SW2 are provided. Is provided.
[0061]
That is, in the present embodiment, SW1 and SW2 can adopt “A side” and “B side” as connection states, respectively. The two switches SW1 and SW2 are switched in accordance with the change from one resonance mode to the other resonance mode in the two types of resonance modes. Here, a specific circuit configuration example for realizing the switching operation will be described with reference to FIG.
[0062]
FIG. 5 shows the input voltage applied to the two types of input electrodes (first and second input regions) of the piezoelectric transformer 13B in accordance with the switching of the two types of resonance modes in the strobe device according to the second embodiment. 5 is a diagram illustrating a circuit configuration of a drive circuit that can be switched, and corresponds to the drive circuit 12, SW1, and SW2 in the circuit configuration of the strobe device shown in FIG.
[0063]
The drive circuit shown in the figure is roughly divided into two so-called half-bridge type drive circuits (121-1 and 121-2) in which two switching elements (field effect transistors (FET), etc.) perform switching operations alternately. 122-1 and 122-2) Drive signals (oscillation signals) from the oscillation circuit 11 to the respective gate terminals of the switching elements 122-1 and 122-2 among the four switching elements in total are provided in parallel. The SWd that can be switched to the “A side” or “B side” and the “B side” terminal of SWd, and an inverting circuit 123 that inverts the polarity (phase) of the input drive signal. It is configured.
[0064]
That is, in the first half-bridge type drive circuit composed of the switching elements 121-1 and 121-2, the drive signal output from the oscillation circuit 11 is input as it is to the respective gate terminals of the two switching elements. The output voltage having the same polarity according to the switching operation is applied to the input electrodes 31A and 31B (first input region) of the piezoelectric transformer 13B, so that the piezoelectric transformer 13B enters a driving state (stress generation state).
[0065]
On the other hand, in the second half-bridge type driving circuit composed of the switching elements 122-1 and 122-2, a driving signal output from the oscillation circuit 11 via SWd is supplied to each gate terminal of the two switching elements. The inverted signal (reverse polarity signal) is input, and an output voltage corresponding to the switching operation is applied to the input electrodes 32A and 32B (first input region) of the piezoelectric transformer 13B, whereby the piezoelectric transformer 13B It becomes a drive state (stress generation state).
[0066]
Here, SWd may be an analog switch or a switching element that combines a three-state buffer and a gate.
[0067]
Next, details of the operation of the strobe device according to the present embodiment having such a drive circuit (FIG. 5) will be described with reference to [Table 1] and FIG.
[0068]
[Table 1] shows the relationship between the polarization directions of the primary side and secondary side regions of the piezoelectric transformer 13B according to the present embodiment and the connection state of the switch SWd.
[0069]
[Table 1]

[0070]
As described above, the piezoelectric transformer 13B that can be employed in the strobe device according to the present embodiment has a plurality of variations in the polarization direction, and more specifically, the first and second elements constituting the primary region. The four cases of cases I to IV shown in [Table 1] are assumed depending on the combination of the polarization direction of the input region and the polarization directions of the first and second output regions constituting the secondary region. The preferable connection state of SWd varies depending on the individual case.
[0071]
That is, in case I, in the piezoelectric transformer 13B, the first and second input regions are polarized in the same direction, and the first and second output regions are polarized in different directions. In this case, SWd needs to be connected to the “B side” when charging the discharge capacitor 3, and to the “A side” when driving the discharge tube 4 to trigger.
[0072]
In Case II, in the piezoelectric transformer 13B, the first and second input regions are polarized in different directions, and the first and second output regions are polarized in different directions. In this case, SWd needs to be connected to the “A side” in the charged state and to the “B side” when driving the trigger.
[0073]
In case III, in the piezoelectric transformer 13B, the first and second input regions are polarized in the same direction, and the first and second output regions are polarized in the same direction. In this case, SWd needs to be connected to the “B side” in the charged state and to the “A side” when driving the trigger.
[0074]
In case IV, in the piezoelectric transformer 13B, the first and second input regions are polarized in different directions, and the first and second output regions are polarized in the same direction. In this case, SWd needs to be connected to the “A side” in the charged state and to the “B side” when driving the trigger.
[0075]
FIG. 6 is a diagram for explaining the operation of the strobe device according to the second embodiment. The first resonance mode (charged state) shown in FIG. 6A and the second resonance mode shown in FIG. The stress distribution in the longitudinal direction inside the piezoelectric transformer 13B in each driving state (trigger state) and the output voltage (effective value) generated at the output terminal due to the stress are shown (note that the piezoelectric transformer 13B is an example) The case I described above is adopted).
[0076]
That is, in the first resonance mode shown in FIG. 6A, in order to charge the charging capacitor 3, the piezoelectric transformer 13B is driven in the 2λ mode and the SWd is connected to the “B side”. The output voltage V1 can be extracted from the output electrode 23 in the secondary region.
[0077]
Then, the driving in the 2λ mode is continued, and, for example, after detecting that the charging capacitor 3 has reached a predetermined full charge state by a circuit (not shown), at a certain timing, to drive the trigger to the discharge tube 4, When the frequency of the oscillation signal supplied from the oscillation circuit 11 to the drive circuit 12 is changed to enter the second resonance mode (λ mode in this example) and SWd is switched to the “A side”, the piezoelectric transformer 13B The state shown in FIG. 6B is taken. As a result, the output voltage V2 can be extracted from the output electrode 22 in the secondary region, and the output voltage V2 is applied to the trigger terminal (not shown) of the discharge tube 4 via the trigger line. Emits light in response to
[0078]
In the above example, in the second resonance mode, the piezoelectric transformer 13B is driven in the λ mode. However, the present invention is not limited to this and may be driven in the λ / 2 mode.
[0079]
Here, in the prior art listed in “Problems to be Solved by the Invention”, two types (first and second) forming a primary side region are provided to facilitate connection between a piezoelectric transformer (piezoelectric transformer element) and the outside. The input region 2) is preferably polarized in opposite directions, but when the polarization directions are different from each other, stress strain at the time of polarization occurs at the boundary between the two types of input regions. There is a problem that it becomes weak in strength.
[0080]
On the other hand, there are the four cases described above as the polarization directions of the piezoelectric transformer 13B. Also in this embodiment, as described above, the polarization directions of the two types (first and second) input regions forming the primary region. Can be made opposite to each other as in case II or case IV, but in that case, it is expected that the same strength problem as in the related art will arise.
[0081]
However, in the present embodiment, when the piezoelectric transformer 13B is driven, it is assumed that the switch SWd is appropriately switched between the two types of input regions (that is, between the two sets of input electrodes) as described above. Therefore, it is not necessary to polarize the two types of input regions in opposite directions. In other words, in the present embodiment, in the piezoelectric transformer 13B, the polarization directions of the two types (first and second) of the input regions forming the primary region are set to the same direction as in the case I or case III, so that the opposite directions are obtained. Compared with the case of polarization in the direction, the device has excellent strength, and the polarization process at the time of manufacture can be facilitated.
[0082]
As described above, in this embodiment, the piezoelectric transformer 13B shown in FIG. 3 is employed in the strobe device having the circuit configuration shown in FIG. 4, so that the two types of output voltages V1 and V2 obtained from the output electrodes 22 and 23 are obtained. The charging method to the discharge capacitor 3 without using a switch (switching element) necessary for the above-described conventional strobe device by the applicant of the present application, by using a method peculiar to the present application by appropriately switching the resonance mode. The trigger function of the discharge tube 4 is appropriately switched.
[0083]
That is, in the present embodiment, the connection state of the switch SWd is switched to “A side” or “B side” in accordance with the switching of the resonance mode, but the SWd is switched in the circuit configuration of the strobe device (FIG. 4). , An oscillation signal output from the oscillation circuit 11. Therefore, unlike the switch (switching element) connected to the secondary side region of the piezoelectric transformer in the above-described conventional strobe device by the applicant of the present application, the switch SWd2 can withstand an AC high voltage of about several kV. It is not necessary to be a high breakdown voltage switching element, and a cheaper and smaller switching element can be adopted as compared with such a switching element.
[0084]
Therefore, according to the piezoelectric transformer 13B according to the present embodiment, mechanical vibration in the primary side region can be promoted, so that the step-up rate is higher than that of the piezoelectric transformer 13A according to the first embodiment described above. The charging speed can be increased. According to the strobe device (FIGS. 4 and 5) including the piezoelectric transformer 13B having such a feature, a strobe device excellent in space saving can be realized with a simple device configuration, and is built in various cameras. Or it is suitable as a strobe device for an external camera. In this case, the switching operation of the two kinds of resonance modes and the switching operation of SWd are performed by, for example, changing the frequency of the oscillation signal supplied from the oscillation circuit 11 to the drive circuit 12 according to the shutter operation of the camera. Realize it.
[0085]
<Modification of Second Embodiment>
FIG. 7 is a block diagram showing a circuit configuration of a strobe device according to a modification of the second embodiment.
[0086]
The strobe device shown in FIG. 7 is based on the same configuration as the strobe device described above with reference to FIG. 4. In this modification, the charging circuit 1B and the trigger circuit 2B include an oscillation circuit 11, a drive circuit 12, In addition, a set of booster circuits composed of the piezoelectric transformer 13B are provided as a common booster, but one of the two types of input areas of the piezoelectric transformer 13B (in the example shown in the figure, the second input area) is provided. In order to invert the phase of the applied input voltage, a point that a phase shift circuit 41 is provided instead of the inversion circuit 123 is different (since a general one can be used for the phase shift circuit 41). Detailed description is omitted).
[0087]
That is, in the circuit configuration described above with reference to FIG. 5, the switch SWd and the inverting circuit 123 are provided in the preceding stage of the second half-bridge type driving circuit including the switching elements 122-1 and 122-2. In this modification, as shown in FIG. 7, when the switch SW3 and the phase shift circuit 41 are provided at the subsequent stage of the drive circuit 12, and the connection state of the SW3 is “B side”, the second input The phase of the input voltage applied to the region (between the input electrodes 32A and 32B) is inverted.
[0088]
Also in this modification, SW3 is “A side” or “B side” in accordance with the resonance mode being changed by changing the frequency of the oscillation signal supplied from the oscillation circuit 11 to the drive circuit 12. The preferred switching operation is determined according to the variation in the polarization direction of the piezoelectric transformer 13B as shown in [Table 1].
[0089]
Also by this modification, it is possible to enjoy the same effect as the strobe device shown in FIG. 4 described above.
[0090]
【The invention's effect】
According to the present invention described above, the capacitor charging function and the discharge tube trigger function can be switched without using a switch (switching element), and the charging circuit and the trigger circuit can be shared as a common boosting means. It is possible to provide a piezoelectric transformer having an excellent step-up ratio and a strobe device including the piezoelectric transformer.
[Brief description of the drawings]
FIG. 1 is a diagram showing a piezoelectric transformer according to a first embodiment, FIG. 1 (a) is a perspective view of the piezoelectric transformer, and FIG. 1 (b) is a piezoelectric diagram shown in FIG. 1 (a). It is the front view which looked at the transformer from this side.
FIG. 2 is a block diagram showing a circuit configuration of the strobe device according to the first embodiment.
3A and 3B are diagrams showing a piezoelectric transformer according to a second embodiment, in which FIG. 3A is a perspective view of the piezoelectric transformer, and FIG. 3B is a piezoelectric transducer shown in FIG. It is the front view which looked at the transformer from this side.
FIG. 4 is a block diagram showing a circuit configuration of a strobe device according to a second embodiment.
FIG. 5 shows an input voltage applied to two types of input electrodes (first and second input regions) of the piezoelectric transformer 13B according to switching between two types of resonance modes in the strobe device according to the second embodiment. It is a figure which illustrates the circuit structure of the drive circuit which can be switched.
FIG. 6 is a diagram for explaining the operation of the strobe device according to the second embodiment.
FIG. 7 is a block diagram showing a circuit configuration of a strobe device according to a modification of the second embodiment.
[Explanation of symbols]
1, 1A, 1B: charging circuit,
2, 2A, 2B: trigger circuit,
3: Discharge capacitor,
4: discharge tube,
11: Oscillator circuit,
12: drive circuit,
13, 13A, 13B: Piezoelectric transformer,
15, 16: Rectifier diode,
21A, 21B, 25A, 25B: input electrodes,
22: Output electrode (secondary interlayer connection conductor),
23: output electrode,
24, 27, 36, 37, 38, 39: primary side interlayer connection conductor,
26A, 26B, 33A, 33B, 34A, 34B: primary side internal electrodes,
28: Secondary side internal electrode,
41: Phase circuit,
121-1, 121-2, 122-1, 122-2: switching elements,
123: Inversion circuit,
SW1 to SW3, SWd: Switch (switching element)

Claims (10)

A piezoelectric transformer having a rectangular outer shape in which one side in the longitudinal direction forms a primary side region and the other forms a secondary side region, and at least two types of input electrodes are formed in the primary side region,
At least two types of output electrodes are formed in the secondary region,
In the primary region of the piezoelectric transformer, as the at least two types of input electrodes, two types of input electrodes that are polarized in the same or opposite directions and to which the same or different input voltages are applied are formed. ,
The input voltage is applied to each of the input electrodes and selectively driven in the plurality of types of resonance modes, so that the at least two types of output electrodes can output a plurality of types of output voltages having different sizes. A piezoelectric transformer characterized in that it can be taken out by switching. 2. The piezoelectric transformer according to claim 1, wherein the at least two types of input electrodes are polarized in the same direction. In the secondary region, two types of output electrodes are formed: an electrode formed at an end portion thereof, and an intermediate electrode formed between the end portion and the primary region,
When the two types of output electrodes are driven in the first resonance mode, the first output voltage can be extracted from the first output electrode, but the second resonance mode is different from the first resonance mode. 3. The piezoelectric device according to claim 1, wherein a second output voltage having a magnitude different from that of the first output voltage can be taken out from the second output electrode when driven by the piezoelectric element. Trance. In the secondary region of the piezoelectric transformer, the polarization direction in the region between the primary region and the intermediate electrode is opposite to the polarization direction in the region between the intermediate electrode and the end of the secondary region. The piezoelectric transformer according to claim 1, wherein the piezoelectric transformer is a direction. 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.
The piezoelectric transformer includes the piezoelectric transformer according to claim 1,
In the booster circuit, by switching and taking out an output voltage from the two types of output electrodes in response to driving the piezoelectric transformer in the first or second resonance mode, the booster circuit is connected to the charging circuit. A strobe device that is switchable for use or for the trigger circuit. In the booster circuit,
When the piezoelectric transformer is driven in the first resonance mode, the capacitor is charged by the first output voltage extracted from the first output electrode of the two types of output electrodes. The piezoelectric transformer is driven in the second resonance mode in response to the switching of the driving state from the first resonance mode to the second resonance mode, so that the output from the second output electrode is extracted. 6. The strobe device according to claim 5, wherein a trigger is driven to the discharge tube by the second output voltage. The booster circuit includes:
7. The strobe device according to claim 5, further comprising switching means for switching input voltages applied to the two types of input electrodes of the piezoelectric transformer. The switching means is
When the piezoelectric transformer is driven in the first resonance mode, a first switching state in which the first and second input regions including the two types of input electrodes are driven in a vibration state in opposite directions to each other. On the other hand, when driven in the second resonance mode, the first and second input regions are in a second switching state in which they are driven in a vibration state in the same direction. 7. The strobe device according to 7. In the booster circuit,
In the primary region of the piezoelectric transformer, the at least two types of input electrodes are polarized in the same direction,
In the secondary region of the piezoelectric transformer, the polarization direction in the region between the primary region and the intermediate electrode is opposite to the polarization direction in the region between the intermediate electrode and the end of the secondary region. Direction,
The switching means is
While the piezoelectric transformer is driven in the first resonance mode, the first switching state in which input voltages having opposite polarities are applied to the first and second input regions is adopted, while the second 9. The strobe device according to claim 8, wherein when driven in a resonance mode, the second switching state is adopted in which input voltages having the same polarity are applied to the first and second input regions. The booster circuit includes:
While driving the piezoelectric transformer in a two-wavelength mode to charge the capacitor in the first resonance mode,
10. The piezoelectric transformer according to claim 5, wherein the piezoelectric transformer is driven in a ½ wavelength mode or a one wavelength mode in order to drive the trigger in the discharge tube in the second resonance mode. 11. Strobe device.

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