JP2004241266A - Lighting driving device of cold-cathode tube - Google Patents

Lighting driving device of cold-cathode tube Download PDF

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Publication number
JP2004241266A
JP2004241266A JP2003029580A JP2003029580A JP2004241266A JP 2004241266 A JP2004241266 A JP 2004241266A JP 2003029580 A JP2003029580 A JP 2003029580A JP 2003029580 A JP2003029580 A JP 2003029580A JP 2004241266 A JP2004241266 A JP 2004241266A
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Prior art keywords
output electrode
output
cold
piezoelectric transformer
cathode tube
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JP2003029580A
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Japanese (ja)
Inventor
Takeshi Fujimura
健 藤村
Masaaki Toyama
正明 外山
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Taiheiyo Cement Corp
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Taiheiyo Cement Corp
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Priority to JP2003029580A priority Critical patent/JP2004241266A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting driving device of a cold-cathode tube capable of equally controlling a plurality of cold-cathode tubes by controlling tube current without increasing loss electric power. <P>SOLUTION: The lighting driving device of the cold-cathode tube is equipped with a one input two output type piezoelectric transformer outputting opposite phase AC voltage from a first output electrode and a second output electrode; a current detecting element inserted between two cold-cathode tubes connected in series between the first output electrode and the second output electrode; a current detecting circuit comprising a first differential amplifier in which voltage at both ends of the current detecting element is inputted; a second differential amplifier comparing output of the current detecting circuit with reference voltage; an oscillation circuit controlling the driving frequency of the piezoelectric transformer so that the current floating through the cold-cathode tube becomes constant based on the output of the second differential amplifier; and a driving circuit inputting AC voltage in the piezoelectric transformer based on the driving frequency oscillated from the oscillation circuit. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、圧電トランスを用いて冷陰極管を点灯駆動する冷陰極管の点灯駆動装置に関する。
【０００２】
【従来の技術】
図４は、従来の冷陰極管点灯駆動装置の構成を示す図である。
図４において、１入力１出力型の圧電トランス１の出力電極１Ａには直列接続された２つの冷陰極管２Ａ、２Ｂが接続されている。
冷陰極管２Ｂの低圧側には、冷陰極管２Ａ、２Ｂに通流する管電流を検出するための電流検出素子３が接続されている。検出された管電流は整流回路４を経て差動増幅器５の反転入力端子に入力される。差動増幅器５の非反転入力端子には基準電圧Ｖｒｅｆが入力されており、また、出力側には、管電流を一定にするように圧電トランス１の駆動周波数を設定する電圧制御発振回路６が接続されている。電圧制御発振回路６で設定された駆動周波数は駆動回路７に伝達され、駆動回路７から冷陰極管１の入力電極に交流電圧が印加される（例えば、特許文献１参照。）。
【０００３】
また、２つの出力電極を有する１入力２出力型の圧電トランスを用い、それぞれの出力電極に冷陰極管を接続して点灯させる冷陰極管点灯駆動装置もあった（例えば、特許文献２参照。）。
【０００４】
【特許文献１】
特開平０８−０４５６７９号公報
【特許文献２】
特開平１０−２４１８８４号公報
【０００５】
【発明が解決しようとする課題】
従来の装置は以上のように構成されていたため、次のような課題が存在していた。
特許文献１記載の発明のように、複数の冷陰極管を直列接続して点灯駆動する場合は、複数の冷陰極管に通流する管電流は一定であり、かつ、複数の冷陰極管を等しく制御することができる。しかし、例えば、２つの冷陰極管を使用する場合は１つの冷陰極管を点灯する場合と比較して圧電トランスの出力電力を２倍にする必要があり、液晶パネルの筐体との寄生容量による損失電力は１灯の場合の４倍になるという課題があった。
【０００６】
また、特許文献２記載の発明のように、１入力２出力型の圧電トランスのそれぞれの出力電極に１灯ずつ冷陰極管を接続させる場合には、液晶パネルの筐体との寄生容量による損失電力は１灯の場合の２倍で済むものの、それぞれの冷陰極管に通流する管電流を制御できないという課題があった。
【０００７】
本発明は、以上のような課題を解決するためになされたもので、特に、消費電力を増大させることなく、すなわち、損失電力を増大させることなく、かつ、管電流を制御することにより、複数の冷陰極管を等しく制御することのできる冷陰極管の点灯駆動装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明の冷陰極管の点灯駆動装置は、第１出力電極及び第２出力電極から互いに逆位相の交流電圧を出力する１入力２出力型の圧電トランスと、前記第１出力電極及び第２出力電極間に直列接続される２つの冷陰極管の間に挿入された電流検出素子と、前記電流検出素子の両端の電圧が入力される第１差動増幅器により構成される電流検出回路と、前記電流検出回路の出力と基準電圧を比較する第２差動増幅器と、前記第２差動増幅器の出力に基づき、前記冷陰極管に通流する電流が一定になるように、前記圧電トランスの駆動周波数を制御する発振回路と、前記発振回路から発振される駆動周波数に基づき、前記圧電トランスに交流電圧を入力する駆動回路とを備え、前記２つの冷陰極管を点灯駆動する。
【０００９】
また、前記圧電トランスは、長板状の圧電体の中央部の上下面に入力電極が配設され、前記圧電体の厚さ方向に分極された駆動部と、前記圧電体の長手方向の両端に前記第１出力電極及び第２出力電極が対向して配設され、前記駆動部と前記第１出力電極間の領域と前記駆動部と前記第２出力電極間の領域が互いに逆方向に分極された発電部とを備える。
【００１０】
また、前記圧電トランスは、長板状の圧電体の長手方向の一端側の上下面に入力電極が配設され、前記圧電体の厚さ方向に分極された駆動部と、前記圧電体の長手方向における他端側の側面或いは上下面に前記第１出力電極及び第２出力電極が対向して配設され、前記第１出力電極から前記第２出力電極の方向に分極した発電部とを備える。
【００１１】
【発明の実施の形態】
以下、図面と共に本発明による冷陰極管の点灯駆動装置の好適な実施の形態について詳細に説明する。
なお、従来装置と同一または同等部分には同一符号を付し、その説明を省略する。
【００１２】
図１は、本発明の冷陰極管の点灯駆動装置の回路構成を示す図である。
圧電トランス１０は、１入力２出力型であり、一対の入力電極１１Ａ、１１Ｂと、対向配置される一対の第１出力電極１２及び第２出力電極１３とを備える。詳細については図２を用いて後述する。
【００１３】
図１に示すように、圧電トランス１０の入力電極１１Ａには、電圧制御発振回路６で設定された駆動周波数に基づいて駆動回路７から交流電圧が印加され、一方、入力電極１１Ｂは、ＧＮＤに接続されている。なお、駆動回路によっては、入力電極Ａと入力電極Ｂそれぞれに入力する方式もあり、圧電トランス１０への入力方法は図１に限定されるものではない。
第１出力電極１２及び第２出力電極１３間には、２つの冷陰極管１４、１５が直列接続されている。
【００１４】
また、２つの冷陰極管１４、１５の間には管電流を検出するための電流検出素子１６が挿入されており、この電流検出素子１６の両端には第１差動増幅器１７の反転入力端子及び非反転入力端子がそれぞれ接続されている。第１差動増幅器の出力端子は整流回路４を介して第２差動増幅器１８の反転入力端子に接続されている。なお、この第２差動増幅器１８は、従来の差動増幅器５と同一のものであるが、第１差動増幅器１７と区別して説明するために別の符号を用いる。また、第２差動増幅器１８の基準電圧Ｖｒｅｆは、直流電源から供給される電圧を抵抗による分圧やツェナーダイオード等を介して生成されるものである。
【００１５】
図２は、本発明の冷陰極管の点灯駆動装置に用いる圧電トランスの構成を示す図である。
図２に示すように、１入力２出力型の圧電トランス１０の入力電極１１Ａ、１１Ｂは、長板状の圧電体の中央部の上下面に配設されており、第１出力電極１２及び第２出力電極１３は、圧電体の長手方向の両端に対向して配設されている。
圧電トランス１０は、入力電極１１Ａ、１１Ｂに挟まれた領域において圧電体の厚さ方向に分極された駆動部１０Ａと、駆動部１０Ａと第１出力電極１２間の領域と駆動部１０Ａと第２出力電極１３間の領域が互いに逆方向に分極された２つの発電部１０Ｂを駆動部１０Ａの両側に備える。
【００１６】
この圧電トランス１０は、λ／２モードまたは３λ／２モードの入力電圧により、第１出力電極１２及び第２出力電極１３から互いに逆位相の交流電圧を出力する。
すなわち、冷陰極管１４、１５の高圧側には互いに逆位相の交流電圧が印加され、同時に点灯駆動される。そして、これら２つの冷陰極管１４、１５に通流する管電流は、電流検出素子１６の両端において電圧値として検出され、冷陰極管１４の低圧側には第１差動増幅器１７の反転入力端子に入力され、冷陰極管１５の低圧側の電圧値が第１差動増幅器１７の非反転入力端子に入力される。
【００１７】
第１差動増幅器１７の出力は、整流器４を介して第２差動増幅器１８の反転入力端子に入力されるので、この第２差動増幅器１８において基準電圧Ｖｒｅｆに対する管電流（第１差動増幅器１７の検出電圧）の大小関係を比較し、出力Ｖｃｔｒが電圧制御発振回路６に入力され、電圧制御発振回路６において、管電流が一定になるように駆動周波数を設定すれば、２つの冷陰極管１４、１５を等しく制御することができる。また、１つの冷陰極管を点灯駆動する場合と同一の出力電圧で２つの冷陰極管１４、１５を同時に点灯駆動でき、この結果、出力電力の増大も回避でき、損失電力を最小限に抑えることができる。
【００１８】
なお、本発明で用いる圧電トランス１０は、図２に示すものに限定されず、図３に示すものでもよい。
すなわち、図３（ａ）、図３（ｂ）に示す圧電トランス１０は、入力電極１１Ａ及び１１Ｂが長板状の圧電体の長手方向の一端側の上下面に配設され、圧電体の厚さ方向に分極された駆動部１０Ａと、第１出力電極１２及び第２出力電極１３が圧電体の長手方向における他端側の側面（図３（ａ））或いは上下面（図３（ｂ））に対向して配設され、第１出力電極１２から第２出力電極１３の方向に分極した発電部１０Ｂとを備える。このような圧電トランス１０を長手方向のλモードや幅方向のλ／２モード等で駆動すればよい。
また、図２及び図３では、説明を簡略にする為、圧電トランスは、駆動部が１層の単板型圧電トランスのように説明したが、当然ながら単板型圧電トランスに限定されるわけではなく、駆動部が厚み方向に積層された構造をもつ積層型圧電トランスであってもよい。
【００１９】
【発明の効果】
本発明の冷陰極管の点灯駆動装置は、第１出力電極及び第２出力電極から互いに逆位相の交流電圧を出力する１入力２出力型の圧電トランスと、前記第１出力電極及び第２出力電極間に直列接続される２つの冷陰極管の間に挿入された電流検出素子と、前記電流検出素子の両端の電圧が入力される第１差動増幅器により構成される電流検出回路と、前記電流検出回路の出力と基準電圧を比較する第２差動増幅器と、前記第２差動増幅器の出力に基づき、前記冷陰極管に通流する電流が一定になるように、前記圧電トランスの駆動周波数を制御する発振回路と、前記発振回路から発振される駆動周波数に基づき、前記圧電トランスに交流電圧を入力する駆動回路とを備え、前記２つの冷陰極管を点灯駆動するので、２つの冷陰極管を等しく制御することができる。また、１つの冷陰極管を点灯駆動する場合と同一の出力電圧で２つの冷陰極管を同時に点灯駆動でき、この結果、出力電力の増大も回避でき、損失電力を最小限に抑えることができる。
【００２０】
また、前記圧電トランスは、長板状の圧電体の中央部の上下面に入力電極が配設され、前記圧電体の厚さ方向に分極された駆動部と、前記圧電体の長手方向の両端に前記第１出力電極及び第２出力電極が対向して配設され、前記駆動部と前記第１出力電極間の領域と前記駆動部と前記第２出力電極間の領域が互いに逆方向に分極された発電部とを備えるので、第１出力電極及び第２出力電極から互いに逆位相の交流電圧を出力することができ、低出力電圧で制御性に優れた冷陰極管の点灯駆動装置を提供することができる。
【００２１】
また、前記圧電トランスは、長板状の圧電体の長手方向の一端側の上下面に入力電極が配設され、前記圧電体の厚さ方向に分極された駆動部と、前記圧電体の長手方向における他端側の側面或いは上下面に前記第１出力電極及び第２出力電極が対向して配設され、前記第１出力電極から前記第２出力電極の方向に分極した発電部とを備えるので、第１出力電極及び第２出力電極から互いに逆位相の交流電圧を出力することができ、低出力電圧で制御性に優れた冷陰極管の点灯駆動装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の冷陰極管の点灯駆動装置の回路構成を示す図である。
【図２】本発明の圧電トランスの構造を概略的に示す図である。
【図３】本発明で用いる他の形態の圧電トランスの構造を概略的に示す図である。
【図４】従来の冷陰極管点灯駆動装置の構成を示す図である。
【符号の説明】
４ 整流回路、６ 電圧制御発振回路、７ 駆動回路、１０ 圧電トランス、１０Ａ 駆動部、１０Ｂ 発電部、１１Ａ、１１Ｂ 入力電極、１２ 第１出力電極、１３ 第２出力電極、１４、１５ 冷陰極管、１６ 電流検出素子、１７第１差動増幅器、１８ 第２差動増幅器。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cold-cathode tube lighting drive device that drives a cold-cathode tube using a piezoelectric transformer.
[0002]
[Prior art]
FIG. 4 is a diagram showing a configuration of a conventional cold-cathode tube lighting driving device.
In FIG. 4, two cold cathode tubes 2A and 2B connected in series are connected to an output electrode 1A of a one-input one-output type piezoelectric transformer 1.
A current detecting element 3 for detecting a tube current flowing through the cold cathode tubes 2A and 2B is connected to the low voltage side of the cold cathode tube 2B. The detected tube current is input to the inverting input terminal of the differential amplifier 5 via the rectifier circuit 4. A reference voltage V ref is input to a non-inverting input terminal of the differential amplifier 5, and a voltage control oscillation circuit 6 for setting a driving frequency of the piezoelectric transformer 1 so as to make the tube current constant is provided on an output side. Is connected. The drive frequency set by the voltage controlled oscillation circuit 6 is transmitted to the drive circuit 7, and the drive circuit 7 applies an AC voltage to the input electrode of the cold-cathode tube 1 (for example, see Patent Document 1).
[0003]
There is also a cold-cathode tube lighting drive device that uses a one-input two-output type piezoelectric transformer having two output electrodes and connects a cold-cathode tube to each of the output electrodes to light up (for example, see Patent Document 2). ).
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 08-045679 [Patent Document 2]
Japanese Patent Application Laid-Open No. H10-241884
[Problems to be solved by the invention]
Since the conventional device was configured as described above, the following problems existed.
When a plurality of CCFLs are connected in series and driven for lighting as in the invention described in Patent Document 1, the tube current flowing through the CCFLs is constant, and the CCFLs are connected to each other. Can be controlled equally. However, for example, when two cold cathode tubes are used, it is necessary to double the output power of the piezoelectric transformer as compared with a case where one cold cathode tube is turned on, and the parasitic capacitance with the liquid crystal panel housing is required. There is a problem that the power loss due to this is four times that of a single lamp.
[0006]
Further, in the case where a cold cathode tube is connected to each output electrode of a one-input two-output type piezoelectric transformer one lamp at a time as in the invention described in Patent Document 2, the loss due to the parasitic capacitance with the liquid crystal panel housing is obtained. Although the power can be doubled as compared with the case of one lamp, there is a problem that the tube current flowing through each cold cathode tube cannot be controlled.
[0007]
The present invention has been made in order to solve the above problems, and in particular, without increasing power consumption, that is, without increasing loss power, and controlling the tube current, It is an object of the present invention to provide a cold-cathode tube lighting drive device capable of equally controlling the cold-cathode tubes.
[0008]
[Means for Solving the Problems]
A lighting drive device for a cold cathode tube according to the present invention includes a one-input two-output piezoelectric transformer that outputs AC voltages having opposite phases from a first output electrode and a second output electrode, and the first output electrode and the second output. A current detecting element inserted between two cold-cathode tubes connected in series between the electrodes, a current detecting circuit including a first differential amplifier to which a voltage across the current detecting element is input; A second differential amplifier that compares the output of the current detection circuit with a reference voltage; and driving the piezoelectric transformer based on the output of the second differential amplifier so that the current flowing through the cold-cathode tube is constant. An oscillation circuit for controlling a frequency, and a drive circuit for inputting an AC voltage to the piezoelectric transformer based on a drive frequency oscillated from the oscillation circuit are provided, and the two cold cathode tubes are turned on.
[0009]
Also, the piezoelectric transformer has input electrodes disposed on upper and lower surfaces of a central portion of a long plate-shaped piezoelectric body, and a driving section polarized in a thickness direction of the piezoelectric body, and both ends in a longitudinal direction of the piezoelectric body. The first output electrode and the second output electrode are disposed to face each other, and a region between the driving unit and the first output electrode and a region between the driving unit and the second output electrode are polarized in opposite directions. And a generated power generation unit.
[0010]
Further, the piezoelectric transformer has a drive unit polarized in a thickness direction of the piezoelectric body, wherein input electrodes are provided on upper and lower surfaces of one end side of a long plate-shaped piezoelectric body in a longitudinal direction, and a longitudinal direction of the piezoelectric body. The first output electrode and the second output electrode are disposed opposite to each other on the side surface or upper and lower surfaces in the direction, and include a power generation unit polarized in a direction from the first output electrode to the second output electrode. .
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a cold cathode tube lighting drive device according to the present invention will be described in detail with reference to the drawings.
The same or equivalent parts as those of the conventional device are denoted by the same reference numerals, and description thereof will be omitted.
[0012]
FIG. 1 is a diagram showing a circuit configuration of a lighting driving device for a cold cathode tube according to the present invention.
The piezoelectric transformer 10 is a one-input two-output type, and includes a pair of input electrodes 11A and 11B, and a pair of a first output electrode 12 and a second output electrode 13 that are arranged to face each other. Details will be described later with reference to FIG.
[0013]
As shown in FIG. 1, an AC voltage is applied to the input electrode 11A of the piezoelectric transformer 10 from the drive circuit 7 based on the drive frequency set by the voltage controlled oscillation circuit 6, while the input electrode 11B is connected to GND. It is connected. It should be noted that, depending on the drive circuit, there is also a method of inputting to each of the input electrode A and the input electrode B, and the input method to the piezoelectric transformer 10 is not limited to FIG.
Two cold cathode tubes 14 and 15 are connected in series between the first output electrode 12 and the second output electrode 13.
[0014]
A current detecting element 16 for detecting a tube current is inserted between the two cold-cathode tubes 14 and 15. Both ends of the current detecting element 16 have inverting input terminals of a first differential amplifier 17. And the non-inverting input terminal are connected to each other. The output terminal of the first differential amplifier is connected to the inverting input terminal of the second differential amplifier 18 via the rectifier circuit 4. Note that the second differential amplifier 18 is the same as the conventional differential amplifier 5, but another reference numeral is used to distinguish it from the first differential amplifier 17. The reference voltage Vref of the second differential amplifier 18 is generated by dividing a voltage supplied from a DC power supply by a resistor, a Zener diode, or the like.
[0015]
FIG. 2 is a diagram showing a configuration of a piezoelectric transformer used in a lighting driving device for a cold cathode tube according to the present invention.
As shown in FIG. 2, the input electrodes 11A and 11B of the one-input two-output type piezoelectric transformer 10 are disposed on the upper and lower surfaces of a central portion of a long plate-shaped piezoelectric body. The two output electrodes 13 are provided to face both ends of the piezoelectric body in the longitudinal direction.
The piezoelectric transformer 10 includes a driving unit 10A polarized in the thickness direction of the piezoelectric body in a region sandwiched between the input electrodes 11A and 11B, a region between the driving unit 10A and the first output electrode 12, the driving unit 10A and the second Two power generating units 10B in which the region between the output electrodes 13 is polarized in opposite directions are provided on both sides of the driving unit 10A.
[0016]
The piezoelectric transformer 10 outputs AC voltages having phases opposite to each other from the first output electrode 12 and the second output electrode 13 according to the input voltage in the λ / 2 mode or the 3λ / 2 mode.
That is, alternating voltages of opposite phases are applied to the high voltage side of the cold cathode tubes 14 and 15, and the lamps are simultaneously driven. The tube current flowing through these two cold cathode tubes 14 and 15 is detected as a voltage value at both ends of the current detecting element 16, and the inverting input of the first differential amplifier 17 is provided on the low voltage side of the cold cathode tube 14. The voltage value on the low voltage side of the cold cathode tube 15 is input to the non-inverting input terminal of the first differential amplifier 17.
[0017]
Since the output of the first differential amplifier 17 is input to the inverting input terminal of the second differential amplifier 18 via the rectifier 4, the output current of the second differential amplifier 18 with respect to the reference voltage Vref (the first differential amplifier) The output Vctr is input to the voltage-controlled oscillation circuit 6 and the driving frequency is set so that the tube current is constant. The cathode tubes 14, 15 can be controlled equally. Further, the two cold cathode tubes 14 and 15 can be simultaneously driven to be lit with the same output voltage as in the case where one cold cathode tube is driven to be lit. As a result, an increase in output power can be avoided and power loss can be minimized. be able to.
[0018]
The piezoelectric transformer 10 used in the present invention is not limited to the one shown in FIG. 2, but may be one shown in FIG.
That is, in the piezoelectric transformer 10 shown in FIGS. 3A and 3B, the input electrodes 11A and 11B are arranged on the upper and lower surfaces of one end in the longitudinal direction of the long plate-shaped piezoelectric body, and the thickness of the piezoelectric body is increased. The drive unit 10A polarized in the vertical direction and the first output electrode 12 and the second output electrode 13 are connected to the other side (FIG. 3A) or the upper and lower surfaces (FIG. 3B) in the longitudinal direction of the piezoelectric body. ), And a power generation unit 10 </ b> B polarized in the direction from the first output electrode 12 to the second output electrode 13. Such a piezoelectric transformer 10 may be driven in a λ mode in the longitudinal direction or a λ / 2 mode in the width direction.
In FIGS. 2 and 3, the piezoelectric transformer is described as a single-plate type piezoelectric transformer having a single-layer drive unit for the sake of simplicity. However, the piezoelectric transformer is naturally limited to a single-plate type piezoelectric transformer. Instead, a laminated piezoelectric transformer having a structure in which the driving units are laminated in the thickness direction may be used.
[0019]
【The invention's effect】
A lighting drive device for a cold cathode tube according to the present invention includes a one-input two-output piezoelectric transformer that outputs AC voltages having opposite phases from a first output electrode and a second output electrode, and the first output electrode and the second output. A current detecting element inserted between two cold-cathode tubes connected in series between the electrodes, a current detecting circuit including a first differential amplifier to which a voltage across the current detecting element is input; A second differential amplifier that compares the output of the current detection circuit with a reference voltage; and driving the piezoelectric transformer based on the output of the second differential amplifier so that the current flowing through the cold-cathode tube is constant. An oscillation circuit for controlling a frequency; and a drive circuit for inputting an AC voltage to the piezoelectric transformer based on a drive frequency oscillated from the oscillation circuit. Controlling the cathode tube equally Rukoto can. Further, two cold cathode tubes can be simultaneously driven and driven with the same output voltage as when one cold cathode tube is driven to be driven. As a result, an increase in output power can be avoided and power loss can be minimized. .
[0020]
Also, the piezoelectric transformer has input electrodes disposed on upper and lower surfaces of a central portion of a long plate-shaped piezoelectric body, and a driving section polarized in a thickness direction of the piezoelectric body, and both ends in a longitudinal direction of the piezoelectric body. The first output electrode and the second output electrode are disposed to face each other, and a region between the driving unit and the first output electrode and a region between the driving unit and the second output electrode are polarized in opposite directions. And a power generating unit, which can output AC voltages having phases opposite to each other from the first output electrode and the second output electrode, and provide a lighting control device for a cold cathode tube with low output voltage and excellent controllability. can do.
[0021]
The piezoelectric transformer may further include a drive unit having input electrodes disposed on upper and lower surfaces on one end side in a longitudinal direction of the long plate-shaped piezoelectric body, and a driving unit polarized in a thickness direction of the piezoelectric body. The first output electrode and the second output electrode are disposed opposite to each other on the side surface or upper and lower surfaces in the direction, and include a power generation unit polarized in a direction from the first output electrode to the second output electrode. Therefore, it is possible to output AC voltages having phases opposite to each other from the first output electrode and the second output electrode, and to provide a cold-cathode tube lighting driving device with low output voltage and excellent controllability.
[Brief description of the drawings]
FIG. 1 is a diagram showing a circuit configuration of a lighting driving device for a cold cathode tube according to the present invention.
FIG. 2 is a view schematically showing a structure of a piezoelectric transformer of the present invention.
FIG. 3 is a view schematically showing a structure of a piezoelectric transformer of another embodiment used in the present invention.
FIG. 4 is a diagram showing a configuration of a conventional cold-cathode tube lighting driving device.
[Explanation of symbols]
Reference Signs List 4 rectifier circuit, 6 voltage controlled oscillation circuit, 7 drive circuit, 10 piezoelectric transformer, 10A drive section, 10B power generation section, 11A, 11B input electrode, 12 first output electrode, 13 second output electrode, 14, 15 cold cathode tube , 16 current detection element, 17 first differential amplifier, 18 second differential amplifier.

Claims (3)

第１出力電極及び第２出力電極から互いに逆位相の交流電圧を出力する１入力２出力型の圧電トランスと、
前記第１出力電極及び第２出力電極間に直列接続される２つの冷陰極管の間に挿入された電流検出素子と、前記電流検出素子の両端の電圧が入力される第１差動増幅器により構成される電流検出回路と、
前記電流検出回路の出力と基準電圧を比較する第２差動増幅器と、
前記第２差動増幅器の出力に基づき、前記冷陰極管に通流する電流が一定になるように、前記圧電トランスの駆動周波数を制御する発振回路と、
前記発振回路から発振される駆動周波数に基づき、前記圧電トランスに交流電圧を入力する駆動回路と
を備え、前記２つの冷陰極管を点灯駆動する冷陰極管の点灯駆動装置。A one-input two-output type piezoelectric transformer that outputs AC voltages having opposite phases from the first output electrode and the second output electrode,
A current detecting element inserted between two cold cathode tubes connected in series between the first output electrode and the second output electrode, and a first differential amplifier to which a voltage across the current detecting element is input. A current detection circuit configured;
A second differential amplifier that compares an output of the current detection circuit with a reference voltage;
An oscillation circuit that controls a driving frequency of the piezoelectric transformer so that a current flowing through the cold-cathode tube is constant based on an output of the second differential amplifier;
A driving circuit for inputting an AC voltage to the piezoelectric transformer based on a driving frequency oscillated from the oscillating circuit; 前記圧電トランスは、長板状の圧電体の中央部の上下面に入力電極が配設され、前記圧電体の厚さ方向に分極された駆動部と、前記圧電体の長手方向の両端に前記第１出力電極及び第２出力電極が対向して配設され、前記駆動部と前記第１出力電極間の領域と前記駆動部と前記第２出力電極間の領域が互いに逆方向に分極された発電部とを備えることを特徴とする請求項１に記載の冷陰極管の点灯駆動装置。The piezoelectric transformer has input electrodes disposed on the upper and lower surfaces of a central portion of a long plate-shaped piezoelectric body, a driving section polarized in the thickness direction of the piezoelectric body, and the both ends in the longitudinal direction of the piezoelectric body. A first output electrode and a second output electrode are disposed facing each other, and a region between the driving unit and the first output electrode and a region between the driving unit and the second output electrode are polarized in opposite directions. The lighting drive device for a cold cathode tube according to claim 1, further comprising a power generation unit. 前記圧電トランスは、長板状の圧電体の長手方向の一端側の上下面に入力電極が配設され、前記圧電体の厚さ方向に分極された駆動部と、前記圧電体の長手方向における他端側の側面或いは上下面に前記第１出力電極及び第２出力電極が対向して配設され、前記第１出力電極から前記第２出力電極の方向に分極した発電部とを備えることを特徴とする請求項１記載の冷陰極管の点灯駆動装置。In the piezoelectric transformer, input electrodes are provided on upper and lower surfaces of one end of a long plate-shaped piezoelectric body in the longitudinal direction, and a driving unit polarized in a thickness direction of the piezoelectric body, The first output electrode and the second output electrode are disposed on opposite side surfaces or upper and lower surfaces so as to face each other, and a power generation unit polarized in a direction from the first output electrode to the second output electrode. The lighting drive device for a cold cathode tube according to claim 1, wherein:
JP2003029580A 2003-02-06 2003-02-06 Lighting driving device of cold-cathode tube Pending JP2004241266A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006041102A1 (en) * 2004-10-13 2006-04-20 Tamura Corporation Transformer driver and method for driving transformer
US7309964B2 (en) 2004-10-01 2007-12-18 Au Optronics Corporation Floating drive circuit for cold cathode fluorescent lamp
CN109598258A (en) * 2018-12-30 2019-04-09 苏州迈瑞微电子有限公司 Ultrasound detection circuit and image sensor pixel circuit and signal detecting method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7309964B2 (en) 2004-10-01 2007-12-18 Au Optronics Corporation Floating drive circuit for cold cathode fluorescent lamp
WO2006041102A1 (en) * 2004-10-13 2006-04-20 Tamura Corporation Transformer driver and method for driving transformer
CN109598258A (en) * 2018-12-30 2019-04-09 苏州迈瑞微电子有限公司 Ultrasound detection circuit and image sensor pixel circuit and signal detecting method
CN109598258B (en) * 2018-12-30 2024-01-30 苏州迈瑞微电子有限公司 Ultrasonic detection circuit, image sensor pixel circuit and signal detection method

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