JP2004205670A

JP2004205670A - Power unit, liquid crystal display device, and power supply method

Info

Publication number: JP2004205670A
Application number: JP2002372748A
Authority: JP
Inventors: Hideki Mine; 秀樹峯
Original assignee: Toshiba Matsushita Display Technology Co Ltd
Current assignee: Japan Display Central Inc
Priority date: 2002-12-24
Filing date: 2002-12-24
Publication date: 2004-07-22

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem in which when an input power source is used as a charging/discharging power source for a compensation capacity by a circuit boosting its voltage, the power consumption of a liquid crystal display device is increased since unnecessary electric power is consumed. <P>SOLUTION: A power unit which supplies a compensating voltage to a liquid crystal display panel for independent CC (Charge-Coupling) driving is equipped with a compensating power circuit 102 which boosts and steps down the input from the input power source 104 to generate two kinds of high and lower compensating voltages, a bypass line 104a for outputting the input from the input power source 104 as it is, and a compensating power source switching circuit 100 which inputs the output from the compensating power circuit 102 and the output from the bypass line 104a and selects and outputs one of the high or low compensating voltage and the input from the input power source 104 to a compensating power line 118. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、テレビジョンなどの映像機器やコンピュータなどの情報機器や携帯電話のディスプレイとして有用な液晶表示装置およびそれに用いる電源装置に関するものである。
【０００２】
【従来の技術】
図５は、近年、よく使用されている独立ＣＣ（Ｃｈａｒｇｅ−Ｃｏｕｐｌｉｎｇ）駆動型の液晶表示装置のブロック図であり、図４、その詳細図であり、図３は、その駆動波形である（例えば、特許文献１を参照）。
【０００３】
図５において、１０１は補償電源、１０２は補償電源作成回路、５０３は従来の電源回路、１０４は液晶表示装置に入力される入力電源、１０７は電源回路制御信号、１０８は制御信号発生回路、１０９は走査電極信号電極制御信号、１１０は走査電極駆動回路群、１１１は信号電極駆動回路群、１１２は補償容量、１１３は液晶層、１１４は液晶パネルの画素トランジスタ、１１５は液晶パネルの画素、１１６は信号電極線、１１７は走査電極線、１１８は補償電極線、１１９対向電極である。
【０００４】
以上のように構成された従来の液晶表示装置の動作を下記に説明する。
【０００５】
図５に示す従来の液晶表示装置は、液晶パネル上に走査電極線１１７と信号電極１１６が設けられ、それぞれの交点には画素トランジスタ１１４が設けられており、画素トランジスタ１１４のゲート側には走査電極線１１７が、ソース側には信号電極線１１６が、ドレイン側には画素電極がつながり、画素電極と対抗電極の間には液晶層１１３が設置されている。
【０００６】
また、走査電極駆動回路群１１０は、補償電極線１１８を駆動する回路も搭載しており、補償電極線１１８につながっている補償電極と画素トランジスタ１１４のドレイン側に液晶層１１３と並列につながっている蓄積電極との間に補償容量１１２を構成し、補償電極線１１８でこの補償容量１１２を駆動する構成となっている。
【０００７】
この信号電極線１１６を駆動するのは、信号電極駆動回路群１１１であり、走査電極線１１７と報償電極線１１８を駆動するのが走査電極駆動回路群１１０である。
【０００８】
制御信号発生回路１０８では、入力信号に基づき、液晶表示装置に表示する画像を信号電極駆動回路群１１１に与える映像信号に加工したり、信号電極駆動回路群１１１を制御する制御信号を発生させたりし、走査電極信号電極制御信号１０９として、信号電極駆動回路群１１１や走査電極駆動回路群１１０に送り、また、入力信号１０２に基づき、従来の電源回路５０３を動作させる電源回路制御信号１０７を発生させ、従来の電源回路５０３へ送る。
【０００９】
従来の電源回路５０３では、電源回路制御信号１０７により、入力電圧１０４を使用して信号電極駆動回路群１１１と走査電極駆動回路群１１０で必要な電源を作成し、それぞれの電極駆動回路群に送るばかりでなく、補償電源作成回路１０２で補償電極線を駆動する補償電源１０１も作成する。
【００１０】
信号電極駆動回路群１１１では、従来の電源回路５０３よりの信号電極駆動用電源と制御信号発生回路１０８よりの映像信号と制御信号である信号電極駆動用信号により、信号電極信号を発生させ、信号電極線１１６を駆動する。
【００１１】
また、走査電極駆動回路群１１０では、従来の電源回路５０３よりの走査電極駆動用電源と制御信号発生回路１０８よりの制御信号である走査電極駆動用信号により、走査電極信号を発生させ、走査電極線１１７を駆動し、かつ、補償電源を使用して、補償電極信号を作成し、補償電極線１１８も駆動する。
【００１２】
このようにして、発生した信号電極信号と走査電極信号と補償電極信号とで液晶表示装置のそれぞれの画素に表示映像を表示させている。
【００１３】
ここで、図４を用いて従来の電源回路５０３の補償電源作成回路１０２についてもう少し詳しく下記に説明する。
【００１４】
図４において、４０１は昇圧回路、４０２は出力電源回路、４０３は補償電源回路である。
【００１５】
以上のように構成された従来の電源回路５０３の補償電源作成回路１０２の動作について、上記では触れなかった部分についての信号の流れを下記に説明する。
【００１６】
液晶表示装置の従来の電源回路５０３内の補償電源作成回路１０２は、昇圧回路４０１と、出力電源回路４０２と、補償電源回路４０３とで構成され、入力電源１０４を昇圧回路４０１で２〜３倍の電圧に一端昇圧し、出力電源回路４０２にて必要な電圧を作成し、たとえば、信号電極駆動回路群１１１で使用するアナログ電源ＡＶＤＤのような信号を作成する。これを電源として使用し、補償電源回路４０３で補償電源１０１を作成し、走査電極駆動回路群１１０に送り、補償電極線１１８を駆動する電源に使用する。
【００１７】
つぎに、図３の信号波形を使用して、上記で説明した液晶表示装置の駆動についてもう少し、詳しく説明する。
【００１８】
図３において、３０１は走査電極線１１７の１ライン目の信号波形Ｇ（１）、３０２は走査電極線１１７の２ライン目の信号波形Ｇ（２）、３０３は走査電極線１１７のｎライン目の信号波形Ｇ（ｎ）、３１１は補償電極線１１８の１ライン目の信号波形ＧＥ（１）、３１２は補償電極線１１８の２ライン目の信号波形ＧＥ（２）、３１３は補償電極線１１８のｎライン目の信号波形ＧＥ（ｎ）、である。
【００１９】
以上のように構成された波形で従来の液晶表示装置における信号について説明する。
【００２０】
画素１１５に内にある画素トランジスタ１１４は、走査電極信号であるＧ（１）３０１、Ｇ（２）３０２、・・・・、Ｇ（ｎ）３０３といった信号波形で、１ライン目、２ライン目、・・・・・ｎライン目と順次、オン／オフさせ、信号電極信号を導通させたり遮断したりする。
【００２１】
走査電極信号により、画素トランジスタ１１４がオンしている期間、信号電極信号が画素トランジスタ１１４を導通し画素電極に加えられ、規定された時間で信号電極信号側から液晶層１１３に一端、電荷を蓄積し、次に、走査電極信号により、画素トランジスタ１１４をオフにさせ、画像情報をホールドする。
【００２２】
次に、画素トランジスタ１１４をオフにさせたあとに、補償電極線１１８により、補償電極信号であるＧＥ（１）３１１、ＧＥ（２）３１２、・・・・、ＧＥ（ｎ）３１３といった信号波形で、走査電極線の信号にある一定期間遅れて１ライン目、２ライン目、・・・・・ｎライン目と順次前ラインとは逆極性で変化し、かつ、１Ｖ期間後は、同一ラインでも逆極性となるように駆動する。
【００２３】
これにより、画素トランジスタ１１４が、一端オフした後、信号電極と対向電極１１９との信号電位差と、補償容量１１２に蓄積された電位により、液晶層１１３に加わる電位差を変化させ、その加えられたトータルの電位によって液晶層１１３のねじれ角を制御し、このような動作を全ての画素で走査線単位に行うことにより、液晶表示装置に映像を表示する。
【００２４】
【特許文献１】
特開平０２−０００９１３号公報
【００２５】
【発明が解決しようとする課題】
従来のＣＣ駆動による液晶表示装置の動作は、以上のようなものであるが、しかしながら、図３の補償電極線１１８に加えられる補償電極信号波形で表示を行っているとき、信号レベル負側から信号レベル正側へ到達するときや、または、信号レベル正側から信号レベル負側へ到達するときは、補償容量１１２に充電あるいは放電させる電荷つまり電流は、入力電源１０４を昇圧動作をさせた電圧からすべて供給されるため従来の電源回路５０３の昇圧回路４０１の昇圧値が大きければ大きいほど入力電源１０４に流れる電流は大きくなる。
【００２６】
たとえば、補償電極線１１８の駆動電源である補償回路駆動電圧１０５の電圧値ＶＧＥが、入力電源１０４の電圧値ＶＣＣの２倍であった場合、昇圧回路４０１は、入力電源１０４を２倍以上に持ち上げる必要があるため、逆に、昇圧回路４０１に流れる電流の値ＩＶＣＣは、入力電源１０４の電流値ＩＶＧＥに換算するとき、２倍になる。つまり、ＶＧＥ＝２ＶＣＣ、ＩＶＣＣ＝２ＩＶＧＥの関係があることになる。
【００２７】
補償電極線の電位、つまり、補償電源回路４０３で作られる補償電極線駆動電圧１０５が電位的に飽和到達するまで、補償電源回路４０３は電流を流し続ける。
【００２８】
これにより、仮に、従来の電源回路１０３の損失がなかった場合、これを入力電源１０４に換算すると、入力電源電流は、補償電源回路４０３に流れる電流の２倍の値をとることとなるが、実際は、必ず、従来の電源回路１０３で損失があるため、さらにこの電流が増えることになる。
【００２９】
つまり、補償電極駆動電圧１０５を入力電源１０４より昇圧して作ることにより、不必要な電力を消費続け、液晶表示装置の消費電力を増やしていることとなっている。
【００３０】
本発明は、かかる点に鑑み、上記の課題となる、消費電力として、補償電極に供給される電圧を抑制する構成となり、低消費電力を実現する液晶表示装置を提供することを目的とするものである。
【００３１】
【課題を解決するための手段】
上記の目的を達成するために、第１の本発明は、マトリックス状に配置された走査電極線（１１７）および画像電極線（１１６）と、前記走査電極線に対応して配置された、所定の周期で変動する高低２種類の電圧の補償電圧を供給する補償電極線（１１８）と、前記走査電極線および前記画像電極線からの信号が入力される表示素子（１１３，１１５，１１９）と、前記補償電極線からの信号が入力される補償キャパシタ（１１２）とを有するＣＣ（Ｃｈａｒｇｅ−Ｃｏｕｐｌｉｎｇ）駆動用の液晶表示パネルに、前記補償電圧を供給する電源装置であって、
外部電源からの入力を昇圧および降圧して、前記高低２種類の補償電圧を生成する補償電圧生成手段（１０２）と、
前記外部電源からの入力をそのまま出力するバイパス手段（１０４ａ）と、
前記補償電圧生成手段からの出力および前記バイパス手段からの出力を入力し、高または低の前記補償電圧もしくは前記外部電源からの入力のいずれかを選択して前記補償電力線に出力する選択出力手段（１００）とを備え、
前記補償電圧が高から低に変動するとき、前記選択出力手段は、高の前記補償電圧、前記外部電源からの入力、低の前記補償電圧がこの順で出力されるよう選択を行い、
前記補償電圧が低から高に変動するとき、前記選択出力手段は、低の前記補償電圧、前記外部電源からの入力、高の前記補償電圧がこの順で出力されるよう選択を行う電源装置である。
【００３２】
また、第２の本発明は、前記補償電圧生成手段は、
前記外部電圧からの入力を昇圧または降圧する昇降圧手段（４０１）と、
前記昇降圧手段からの出力を前記補償電力線に出力する前記高低２種類の補償電圧の信号に変換する変換手段（４０３）とを備えた第１の本発明の電源装置である。
【００３３】
また、第３の本発明は、マトリックス状に配置された走査電極線（１１７）および画像電極線（１１６）と、前記走査電極線に対応して配置された、所定の周期で変動する高低２種類の電圧の補償電圧を供給する補償電極線（１１８）と、前記走査電極線および前記画像電極線からの信号が入力される表示素子（１１３，１１５，１１９）と、前記補償電極線からの信号が入力される補償キャパシタ（１１２）とを有するＣＣ（Ｃｈａｒｇｅ−Ｃｏｕｐｌｉｎｇ）駆動用の液晶表示パネルと、
前記走査電極線、前記画像電極線および前記補償電極線にそれぞれ対応する信号を供給する信号供給手段（１１０、１１１）とを備え、
前記信号供給手段は、第１または第２の本発明の電源装置を有し、前記補償信号線に、前記高低２種類の補償電圧の信号もしくは前記外部電源からの入力を供給する液晶表示装置である。
【００３４】
また、第４の本発明は、マトリックス状に配置された走査電極線（１１７）および画像電極線（１１６）と、前記走査電極線に対応して配置された、所定の周期で変動する高低２種類の電圧の補償電圧を供給する補償電極線と、前記走査電極線および前記画像電極線からの信号が入力される表示素子と、前記補償電極線からの信号が入力される補償キャパシタとを有するＣＣ（Ｃｈａｒｇｅ−Ｃｏｕｐｌｉｎｇ）駆動用の液晶表示パネルに、前記補償電圧を供給する電源供給方法であって、
外部電源からの入力を昇圧および降圧して、前記高低２種類の補償電圧を生成する補償電圧生成工程と、
前記外部電源からの入力をそのまま出力するバイパス工程と、
前記補償電圧生成工程からの出力および前記バイパス工程からの出力を入力し、高または低の前記補償電圧もしくは前記外部電源からの入力のいずれかを選択して前記補償電力線に出力する選択出力工程とを備え、
前記補償電圧が高から低に変動するとき、前記選択出力工程は、高の前記補償電圧、前記外部電源からの入力、低の前記補償電圧がこの順で出力されるよう選択を行い、
前記補償電圧が低から高に変動するとき、前記選択出力工程は、低の前記補償電圧、前記外部電源からの入力、高の前記補償電圧がこの順で出力されるよう選択を行う電源供給方法である。
【００３５】
【発明の実施の形態】
以下に本発明を、その実施の形態を示す図面に基づいて説明する。
【００３６】
（実施の形態１）
図１に、本発明の実施の形態による液晶表示装置の構成図を示し、図２に、その信号波形を示す。
【００３７】
図１において、１００は補償電源切替回路、１０１は補償電源、１０２は補償電源作成回路、１０３は電源回路、１０４は液晶表示装置に入力される入力電源、１０５は補償電極線駆動電圧、１０６は補償電極駆動電源制御信号、１０７は電源回路制御信号、１０８は制御信号発生回路、１０９は走査電極信号電極制御信号、１１０は走査電極駆動回路群、１１１は信号電極駆動回路群、１１２は補償容量、１１３は液晶層、１１４は、本発明の液晶パネルの画素トランジスタ、１１５は液晶パネルの画素、１１６は信号電極線、１１７は走査電極線、１１８は補償電極線、１１９は対向電極である。また、１０４ａは、補償電源切替回路１００と入力電源１０４とを接続するバイパス線である。
【００３８】
以上のように構成された、本発明の実施の形態による液晶表示装置について説明するとともに、これにより、本発明の電源供給方法の一実施の形態について説明を行う。
【００３９】
本実施の形態の液晶表示装置の電源回路１０３は、従来の電源回路５０３とは異なり、補償電源作成回路１０２で作成した補償電源１０１と、バイパス線１０４ａを介して直接入力される入力電源１０４とを、補償電極駆動電源制御信号１０６により、１水平期間中の任意の規定された時間で切り替える補償電源切替回路１００を内蔵しており、補償電源１０１と入力電源１０４とを切替え、そのうちのいずれかを走査電極駆動回路群１０９に入力し、補償電極線１１８を駆動する信号を作成し、補償容量１１２に電荷を充放電する構成となっている。
【００４０】
つぎに、図２の信号波形を使用して、上記で説明した構成で、補償電極線１１８に接続された補償容量１１２を駆動する補償電源１０１と、入力電源１０４との切替えについて、もう少し詳しく説明する。
【００４１】
図２において、２０１は従来の補償電源からの電圧ＶＧＥｎの正極変化波形、２１１は従来の補償電源からの電圧ＶＧＥｎの負極変化波形、２０２は本実施の形態の補償電源１０１からの電圧ＶＧＥｎの正極変化波形、２１２は本実施の形態の補償電源１０１からの電圧ＶＧＥｎの負極変化波形である。
【００４２】
ここでは、説明を簡単にするため、入力電圧１０４が２倍であるものとして説明する。
【００４３】
まず、電源回路１０３において、入力電圧１０４は昇圧回路４０１により昇圧される。電圧レベルを入力電源１０４から補償電源回路４０３で使用できる電源を出力電源回路４０２で作成し、電圧値が持ち上げられる。この２倍に昇圧された電源を使用して、補償電源回路４０３で補償電極線駆動電圧１０５を作成し、最終的には、走査電極駆動回路群１１０で補償電極線１１８の駆動電圧を作成する。
【００４４】
通常、補償電極線１１８の信号レベルが従来の電圧ＶＧＥｎの正極変化波形２０１のように負側から正側へ到達するときや、従来の電圧ＶＧＥｎの負極変化波形２１１のように信号レベルが正側から負側へ到達するときは、補償容量に充電あるいは放電させる電荷つまり電流は、入力電圧１０４を昇圧動作をさせた電圧を使用した補償電源回路４０３からすべて供給されるため、補償電極回路４０３に流れる電流は、入力電源１０４の値に換算すると、その２倍になる。
【００４５】
つまり、補償電極線駆動電圧１０５である電圧ＶＧＥ＿Ｈｉは、入力電源１０４の電圧をＶＣＣとして計算式で表すと、
【００４６】
【数１】
ＶＣＣ＜ＶＧＥ＿Ｈｉ≦２ＶＣＣ
となり、補償電極線駆動電圧１０５に流れる電流ＩＶＧＥと入力電源１０４に流れる電流ＩＶＣＣの関係を計算式で表すと、
【００４７】
【数２】
ＩＶＣＣ＝２ＩＶＧＥ
となる。
【００４８】
ここで、本実施の形態では、補償電極線１１８の信号レベルが負側から正側へ到達するとき、つまり補償容量１１２を充電するとき、１水平期間の所定の時間で、補償容量１１２を負側の電位ＶＧＥ＿Ｌｏから入力電源１０４の電位ＶＣＣになるまで入力電源１０４から直接充電を行い、１水平期間の残りの期間で、入力電源１０４の電位ＶＣＣから補償電極線１１８の正側の電位ＶＧＥ＿Ｈｉまで、補償電源回路４０３の出力信号で充電を行うことにより、図２の正極変化波形２０２に示すように、補償容量１１２は２段階で充電されたことになる。
【００４９】
このとき補償電極線１１８に流れる電流値を入力電源１０４の電流値に換算すると、補償容量１１２が負側の電位から入力電源１０４の電位ＶＣＣまで充電される第１の期間は、入力電源１０４の１倍の電流となる一方、入力電源１０４の電位ＶＣＣから補償容量１１２の正側の電位ＶＧＥ＿Ｈｉまで充電される第２の期間は入力電源１０４の値の２倍になる。これは、補償電源回路４０３に流れる電流が２倍昇圧より作成されているためである。
【００５０】
これらを合計すると、入力電源１０４から補償容量線１１８へ供給される電流値ＩＶＧＥは、各段階に応じてそれぞれ下記のような値になる。つまり、上記第１の期間はＩＶＧＥ＝ＩＶＣＣ、上記第２の期間はＩＶＧＥ＝（１／２）ＩＶＣＣとなる。
【００５１】
ここで、上記第１の期間における電流値をＩ１とし、上記第２の期間における電流値をＩ２とすると、入力電源１０４に流れる電流値の総計は、従来では、（Ｉ１＋Ｉ２）×２となり、本実施の形態では、（Ｉ１＋Ｉ２）×２、となる。よって、両者の差は、（従来の電流値）−（本実施の形態の電流値）＝Ｉ１となり、本実施の形態は、従来例に比してＩ１分の電流を抑制でき、低電力化が可能となる。
【００５２】
実際は、必ず電源回路１０３の昇圧回路４０１で損失があるため、さらにこの電流が増えることになるが、入力電源１０４を直接入力した場合、損失は発生しないことにより、この損失を考慮すると、従来では、（Ｉ１＋Ｉ２）×２×（１＋損失率）となり、本実施の形態では、（Ｉ１＋Ｉ２）×２×（１＋損失率）となる。
【００５３】
したがって、昇圧回路４０１による損失を考慮した場合でも、（従来の電流値）−（本実施の形態の電流値）＝Ｉ１（１＋２×損失率分）となり、Ｉ１（１＋２×損失率分）の電流を抑制でき、低電力化が可能となる。
【００５４】
補償電源作成回路１０２にはたいてい損失があるため、損失が大きければ大きいほど、さらなる消費電力を低減できる効果が大きくなることになる。
【００５５】
一方、補償電極線１１８の信号レベルが正側の電位から負側の電位へ到達するとき、つまり補償容量１１２を放電するとき、１水平期間の所定の時間で、補償容量１１２を正側の電位ＶＧＥ＿Ｈｉから入力電源１０４の電位ＶＣＣになるまで入力電源１０４から直接的に放電を行い、１水平期間の残りの期間で、入力電源１０４の電位ＶＣＣから補償電極線１１８の負側の電位ＶＧＥ＿Ｌｏまで、補償電源回路４０３の出力信号で放電を行うことにより、図２の正極変化波形２１２に示すように、補償容量１１２は２段階で放電されたことになる。
【００５６】
このときにも、補償容量１２を充電した場合と同様の計算式が成り立ち、Ｉ１（１＋２×損失率分）の電流を抑制でき、低電力化が可能となる。
【００５７】
以上述べたように、本実施の形態によれば、補償容量１１２の充電期間および放電期間のそれぞれにおいて、全工程において補償電源作成回路１０２からの出力を用いるのではなく、所定の期間で入力電源１０４で直接充電、放電する工程を挟むことにより、不必要な電力の消費を抑制し、液晶表示装置の消費電力を低減できることとなる。
【００５８】
なお、上記の実施の形態において、入力電源１０４は本発明の外部電源に相当し、補償電源作成回路１０２は本発明の補償電圧作成手段に相当し、バイパス線１０４ａは本発明のバイパス手段に相当し、補償電源切替回路１００は、本発明の選択出力手段に相当する。また、昇圧回路４０１は本発明の昇降圧手段に相当し、補償電源回路４０３は本発明の変換手段に相当する。
【００５９】
また、正側の電位ＶＧＥ＿Ｈｉは本発明の高の補償電圧に相当し、負側の電位ＶＧＥ＿Ｌｏは本発明の低の補償電圧に相当し、入力電源１０４の電圧ＶＣＣは、本発明の外部電源からの入力の電圧に相当する。
【００６０】
また、走査電極駆動回路群１１０、信号電極駆動回路群１１１は本発明の信号供給手段を構成し、液晶層１１３、画素トランジスタ１１４、画素１１５、信号電極線１１６、走査電極線１１７、補償電極線１１８、対向電極１１９、補償容量１１２は本発明の液晶表示パネルを構成し、液晶層１１３，画素トランジスタ１１４，画素１１５，対向電極１１９は本発明の表示素子を構成し、補償容量１１２は本発明の補償キャパシタに相当する。
【００６１】
ただし本発明は上記の実施の形態に限定されるものではない。また、上記の実施の形態においては、液晶表示装置を例に説明を行ったが、独立ＣＣ駆動する液晶パネルに補償電圧を供給するための電源装置として実現してもよい。この場合、補償電源作成回路１０２において、補償電源回路４０３は出力電源回路４０２からの信号に基づき補償電源を生成していたが、昇圧回路４０１から直接生成する構成としてもよい。
【００６２】
また、昇圧率（もしくは降圧率）を２倍として説明したが、昇圧率（もしくは降圧率）は、１以上の数値であればどんな数値であってもよい。
【００６３】
また、本発明の所定の周期の一例として、補償電圧の正側と負側の間の電位の変動が行われる周期は１垂直同期期間（１Ｖ期間）であるとしたが、他の周期であってもよい。また、補償電圧の正側と負側との電位の変動そのものの期間は１水平同期期間（１Ｈ期間）であるとしたが、その間に外部電源の電圧で直接充電、放電する工程が挟まれる限り他の周期であってもよい。
【００６４】
【発明の効果】
以上説明したように、本発明は、昇圧回路での電流ロスを抑制することができ、その結果、消費電力を抑制することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態における液晶表示装置の構成を示す図
【図２】本発明の実施の形態における液晶表示装置の信号波形を示す図
【図３】従来の液晶表示装置の信号波形を示す図
【図４】従来の液晶表示装置の電源回路の詳細構成図
【図５】従来の液晶表示装置の全体構成図
【符号の説明】
１００補償電源切替回路
１０１補償電源
１０２補償電源作成回路
１０３電源回路
１０４液晶表示装置に入力される入力電源
１０５補償電極線駆動電圧
１０６補償電極駆動電源制御信号
１０７電源回路制御信号
１０８制御信号発生回路
１０９走査電極信号電極制御信号
１１０走査電極駆動回路群
１１１信号電極駆動回路群
１１２補償容量
１１３液晶層
１１４液晶パネルの画素トランジスタ
１１５液晶パネルの画素
１１６信号電極線
１１７走査電極線
１１８補償電極線
１１９対向電極
２０１従来の電位ＶＧＥｎの正極変化波形
２０２従来の電位ＶＧＥｎの負極変化波形
２１１本実施の形態の電位ＶＧＥｎの正極変化波形
２１２本実施の形態の電位ＶＧＥｎの負極変化波形
３０１走査電極線１１７の１ライン目の信号波形Ｇ１
３０２走査電極線１１７の２ライン目の信号波形Ｇ２
３０３走査電極線１１７のｎライン目の信号波形Ｇｎ
３１１補償電極線１１８の１ライン目の信号波形ＧＥ１
３１２補償電極線１１８の２ライン目の信号波形ＧＥ２
３１３補償電極線１１８のｎライン目の信号波形ＧＥｎ
４０１昇圧回路
４０２出力電源回路
４０３補償電源回路
５０３従来の電源回路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device useful as a display of a video device such as a television, an information device such as a computer, and a mobile phone, and a power supply device used therefor.
[0002]
[Prior art]
FIG. 5 is a block diagram of an independent CC (Charge-Coupling) driving type liquid crystal display device that is often used in recent years, and FIG. 4 is a detailed diagram thereof, and FIG. 3 is a driving waveform thereof (for example, FIG. , Patent Document 1).
[0003]
5, reference numeral 101 denotes a compensation power supply, 102 denotes a compensation power generation circuit, 503 denotes a conventional power supply circuit, 104 denotes an input power supply input to the liquid crystal display device, 107 denotes a power supply circuit control signal, 108 denotes a control signal generation circuit, 109 Is a scanning electrode signal electrode control signal, 110 is a scanning electrode driving circuit group, 111 is a signal electrode driving circuit group, 112 is a compensation capacitor, 113 is a liquid crystal layer, 114 is a pixel transistor of a liquid crystal panel, 115 is a pixel of a liquid crystal panel, 116 Is a signal electrode line, 117 is a scanning electrode line, 118 is a compensation electrode line, and 119 is a counter electrode.
[0004]
The operation of the conventional liquid crystal display device configured as described above will be described below.
[0005]
In the conventional liquid crystal display device shown in FIG. 5, a scanning electrode line 117 and a signal electrode 116 are provided on a liquid crystal panel, and a pixel transistor 114 is provided at each intersection. The electrode line 117 is connected to the signal electrode line 116 on the source side, the pixel electrode is connected to the drain side, and the liquid crystal layer 113 is provided between the pixel electrode and the counter electrode.
[0006]
The scan electrode drive circuit group 110 also includes a circuit for driving the compensation electrode line 118, and is connected to the compensation electrode connected to the compensation electrode line 118 and the drain side of the pixel transistor 114 in parallel with the liquid crystal layer 113. A compensation capacitor 112 is formed between the storage capacitor and the storage electrode, and the compensation capacitor 112 is driven by a compensation electrode line 118.
[0007]
The signal electrode line 116 is driven by the signal electrode drive circuit group 111, and the scan electrode line 117 and the reward electrode line 118 are driven by the scan electrode drive circuit group 110.
[0008]
The control signal generation circuit 108 processes an image to be displayed on the liquid crystal display device into a video signal to be given to the signal electrode drive circuit group 111 based on the input signal, or generates a control signal for controlling the signal electrode drive circuit group 111. Then, the signal is sent to the signal electrode drive circuit group 111 and the scan electrode drive circuit group 110 as the scan electrode signal electrode control signal 109, and the power supply circuit control signal 107 for operating the conventional power supply circuit 503 is generated based on the input signal 102. And sends it to the conventional power supply circuit 503.
[0009]
In the conventional power supply circuit 503, a power supply required for the signal electrode drive circuit group 111 and the scan electrode drive circuit group 110 is created by using the input voltage 104 by the power supply circuit control signal 107 and sent to each of the electrode drive circuit groups. In addition, the compensation power supply 101 for driving the compensation electrode line is also created by the compensation power supply creation circuit 102.
[0010]
In the signal electrode drive circuit group 111, a signal electrode signal is generated by a signal electrode drive power supply from the conventional power supply circuit 503, a video signal from the control signal generation circuit 108, and a signal electrode drive signal as a control signal. The electrode lines 116 are driven.
[0011]
The scan electrode drive circuit group 110 generates a scan electrode signal based on a scan electrode drive power supply from the conventional power supply circuit 503 and a scan electrode drive signal which is a control signal from the control signal generation circuit 108, Driving line 117 and using the compensating power supply to create a compensating electrode signal and also driving compensating electrode line 118.
[0012]
Thus, a display image is displayed on each pixel of the liquid crystal display device by the generated signal electrode signal, scan electrode signal, and compensation electrode signal.
[0013]
Here, the compensation power generation circuit 102 of the conventional power supply circuit 503 will be described in more detail below with reference to FIG.
[0014]
4, reference numeral 401 denotes a booster circuit, 402 denotes an output power supply circuit, and 403 denotes a compensation power supply circuit.
[0015]
Regarding the operation of the compensated power supply generation circuit 102 of the conventional power supply circuit 503 configured as described above, the flow of signals in the portions not mentioned above will be described below.
[0016]
The compensating power supply generating circuit 102 in the conventional power supply circuit 503 of the liquid crystal display device includes a booster circuit 401, an output power supply circuit 402, and a compensation power supply circuit 403. , And the output power supply circuit 402 creates a necessary voltage, for example, creates a signal such as an analog power supply AVDD used in the signal electrode drive circuit group 111. This is used as a power supply, a compensation power supply circuit 403 creates a compensation power supply 101, sends it to the scan electrode drive circuit group 110, and uses it as a power supply for driving the compensation electrode line 118.
[0017]
Next, the driving of the above-described liquid crystal display device will be described in more detail with reference to the signal waveform of FIG.
[0018]
3, reference numeral 301 denotes a signal waveform G (1) of the first line of the scanning electrode line 117, 302 denotes a signal waveform G (2) of the second line of the scanning electrode line 117, and 303 denotes an nth line of the scanning electrode line 117. 311 are the signal waveforms GE (1) of the first line of the compensation electrode line 118, 312 are the signal waveforms GE (2) of the second line of the compensation electrode line 118, and 313 are the compensation electrode lines 118. , The signal waveform GE (n) of the n-th line.
[0019]
A signal in the conventional liquid crystal display device will be described with the waveform configured as described above.
[0020]
The pixel transistor 114 in the pixel 115 has a signal waveform of G (1) 301, G (2) 302,... ,... Are turned on / off sequentially from the n-th line, and the signal electrode signal is turned on or off.
[0021]
During the period when the pixel electrode 114 is turned on by the scanning electrode signal, the signal electrode signal is conducted to the pixel transistor 114 to be applied to the pixel electrode, and a charge is accumulated at the liquid crystal layer 113 from the signal electrode signal side for a specified time. Then, the pixel transistor 114 is turned off by the scanning electrode signal, and the image information is held.
[0022]
Next, after the pixel transistor 114 is turned off, signal waveforms such as GE (1) 311, GE (2) 312,... The first line, the second line,..., The nth line and the preceding line sequentially change in reverse polarity with a certain period behind the signal of the scanning electrode line, and the same line after the 1V period. However, it is driven to have the opposite polarity.
[0023]
Thus, after the pixel transistor 114 is turned off once, the potential difference applied to the liquid crystal layer 113 is changed by the signal potential difference between the signal electrode and the counter electrode 119 and the potential accumulated in the compensation capacitor 112, and the added total The torsion angle of the liquid crystal layer 113 is controlled by the electric potential of the liquid crystal layer 113, and such an operation is performed for every pixel in each scanning line, whereby an image is displayed on the liquid crystal display device.
[0024]
[Patent Document 1]
JP-A-02-000913
[Problems to be solved by the invention]
The operation of the liquid crystal display device by the conventional CC drive is as described above. However, when the display is performed by the compensation electrode signal waveform applied to the compensation electrode line 118 in FIG. When the signal level reaches the positive side or when the signal level reaches the negative side from the positive side, the charge or current that charges or discharges the compensation capacitor 112 is a voltage at which the input power supply 104 is boosted. , The larger the boosted value of the booster circuit 401 of the conventional power supply circuit 503, the larger the current flowing to the input power supply 104.
[0026]
For example, when the voltage value VGE of the compensation circuit driving voltage 105, which is the driving power source of the compensation electrode line 118, is twice the voltage value VCC of the input power source 104, the booster circuit 401 increases the input power source 104 to twice or more. Conversely, the value IVCC of the current flowing through the booster circuit 401 is doubled when converted into the current value IVGE of the input power supply 104 because it is necessary to raise the current. That is, there is a relationship of VGE = 2VCC and IVCC = 2IVGE.
[0027]
The compensation power supply circuit 403 continues to flow current until the potential of the compensation electrode line, that is, the compensation electrode line drive voltage 105 generated by the compensation power supply circuit 403 reaches the potential saturation.
[0028]
As a result, if there is no loss in the conventional power supply circuit 103, when this is converted into the input power supply 104, the input power supply current has a value twice as large as the current flowing through the compensation power supply circuit 403. Actually, since the conventional power supply circuit 103 always has a loss, the current further increases.
[0029]
That is, by increasing the compensation electrode drive voltage 105 from the input power supply 104, unnecessary power is continuously consumed, and the power consumption of the liquid crystal display device is increased.
[0030]
In view of the above, an object of the present invention is to provide a liquid crystal display device that has a configuration that suppresses the voltage supplied to the compensation electrode as power consumption, which is the above problem, and that achieves low power consumption. It is.
[0031]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention is to provide a scanning electrode line (117) and an image electrode line (116) arranged in a matrix and a predetermined arrangement arranged corresponding to the scanning electrode line. A compensating electrode line (118) for supplying two kinds of high and low compensating voltages that fluctuate in a cycle of (1), and display elements (113, 115, 119) to which signals from the scanning electrode line and the image electrode line are inputted. A power supply device for supplying the compensation voltage to a liquid crystal display panel for driving a CC (Charge-Coupling) having a compensation capacitor (112) to which a signal from the compensation electrode line is inputted.
Compensation voltage generating means (102) for boosting and stepping down an input from an external power supply to generate the high and low compensation voltages;
A bypass unit (104a) for directly outputting the input from the external power supply;
Selection output means for inputting the output from the compensation voltage generation means and the output from the bypass means, selecting either the high or low compensation voltage or the input from the external power supply and outputting to the compensation power line 100) and
When the compensation voltage fluctuates from high to low, the selection output means performs selection so that the high compensation voltage, the input from the external power supply, and the low compensation voltage are output in this order,
When the compensation voltage fluctuates from low to high, the selection output means is a power supply device that selects so that the low compensation voltage, the input from the external power supply, and the high compensation voltage are output in this order. is there.
[0032]
Further, according to a second aspect of the present invention, the compensation voltage generating means includes:
Step-up / step-down means (401) for stepping up or stepping down an input from the external voltage;
The power supply device according to the first aspect of the present invention, further comprising: a conversion unit (403) configured to convert an output from the step-up / step-down unit to a signal of the two kinds of high and low compensation voltages that is output to the compensation power line.
[0033]
Further, the third aspect of the present invention relates to a scanning electrode line (117) and an image electrode line (116) which are arranged in a matrix, and a height which varies in a predetermined cycle and which is arranged corresponding to the scanning electrode line. A compensation electrode line (118) for supplying a compensation voltage of a different voltage; a display element (113, 115, 119) to which signals from the scanning electrode line and the image electrode line are input; A liquid crystal display panel for driving a CC (Charge-Coupling) having a compensation capacitor (112) to which a signal is input;
Signal supply means (110, 111) for supplying signals corresponding to the scanning electrode lines, the image electrode lines, and the compensation electrode lines, respectively.
The signal supply means includes a power supply device according to the first or second aspect of the present invention, and supplies a signal of the two kinds of high and low compensation voltages or an input from the external power supply to the compensation signal line. is there.
[0034]
Further, according to a fourth aspect of the present invention, there is provided a scanning electrode line (117) and an image electrode line (116) arranged in a matrix, and a height 2 which is arranged corresponding to the scanning electrode line and fluctuates at a predetermined cycle. Compensation electrode lines for supplying compensation voltages of different voltages, display elements to which signals from the scanning electrode lines and the image electrode lines are inputted, and compensation capacitors to which signals from the compensation electrode lines are inputted. A power supply method for supplying the compensation voltage to a liquid crystal display panel for CC (Charge-Coupling) driving,
A compensation voltage generation step of boosting and stepping down an input from an external power supply to generate the high and low compensation voltages;
A bypass step of directly outputting an input from the external power supply,
A selection output step of inputting the output from the compensation voltage generation step and the output from the bypass step, selecting either the high or low compensation voltage or the input from the external power supply, and outputting to the compensation power line. With
When the compensation voltage fluctuates from high to low, the selecting and outputting step selects such that the high compensation voltage, the input from the external power supply, and the low compensation voltage are output in this order,
When the compensation voltage varies from low to high, the selecting and outputting step includes a power supply method for selecting so that the low compensation voltage, the input from the external power supply, and the high compensation voltage are output in this order. It is.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings showing the embodiments.
[0036]
(Embodiment 1)
FIG. 1 shows a configuration diagram of a liquid crystal display device according to an embodiment of the present invention, and FIG. 2 shows a signal waveform thereof.
[0037]
In FIG. 1, reference numeral 100 denotes a compensation power supply switching circuit, 101 denotes a compensation power supply, 102 denotes a compensation power generation circuit, 103 denotes a power supply circuit, 104 denotes an input power input to the liquid crystal display device, 105 denotes a compensation electrode line drive voltage, and 106 denotes a compensation electrode line drive voltage. Compensation electrode drive power supply control signal, 107 is a power supply circuit control signal, 108 is a control signal generation circuit, 109 is a scan electrode signal electrode control signal, 110 is a scan electrode drive circuit group, 111 is a signal electrode drive circuit group, 112 is a compensation capacitor , 113 are liquid crystal layers, 114 is a pixel transistor of the liquid crystal panel of the present invention, 115 is a pixel of the liquid crystal panel, 116 is a signal electrode line, 117 is a scanning electrode line, 118 is a compensation electrode line, and 119 is a counter electrode. A bypass line 104a connects the compensation power supply switching circuit 100 and the input power supply 104.
[0038]
The liquid crystal display device according to the embodiment of the present invention configured as described above will be described, and the embodiment of the power supply method of the present invention will be described.
[0039]
The power supply circuit 103 of the liquid crystal display device of the present embodiment is different from the conventional power supply circuit 503 in that the compensation power supply 101 created by the compensation power supply creation circuit 102 and the input power supply 104 directly input via the bypass line 104a. , A compensation power supply control circuit 106 that switches the compensation power supply at an arbitrary prescribed time during one horizontal period, and switches between the compensation power supply 101 and the input power supply 104. Is input to the scan electrode drive circuit group 109, a signal for driving the compensation electrode line 118 is generated, and the compensation capacitor 112 is charged and discharged.
[0040]
Next, switching between the compensation power supply 101 for driving the compensation capacitor 112 connected to the compensation electrode line 118 and the input power supply 104 in the above-described configuration using the signal waveform of FIG. 2 will be described in more detail. I do.
[0041]
2, reference numeral 201 denotes a positive-polarity change waveform of the voltage VGEn from the conventional compensation power supply, 211 denotes a negative-polarity change waveform of the voltage VGEn from the conventional compensation power supply, and 202 denotes a positive polarity of the voltage VGEn from the compensation power supply 101 of the present embodiment. A change waveform 212 is a negative change waveform of the voltage VGEn from the compensation power supply 101 according to the present embodiment.
[0042]
Here, for the sake of simplicity, the description will be made assuming that the input voltage 104 is double.
[0043]
First, in the power supply circuit 103, the input voltage 104 is boosted by the booster circuit 401. A power supply whose voltage level can be used by the compensation power supply circuit 403 from the input power supply 104 is generated by the output power supply circuit 402, and the voltage value is raised. By using the power source that has been boosted twice, the compensating power supply circuit 403 creates the compensating electrode line driving voltage 105, and finally, the scan electrode driving circuit group 110 creates the compensating electrode line 118 driving voltage. .
[0044]
Normally, when the signal level of the compensation electrode line 118 reaches the positive side from the negative side like the positive polarity change waveform 201 of the conventional voltage VGEn, or when the signal level changes to the positive side like the conventional negative change waveform 211 of the voltage VGEn. When the charge reaches the negative side from the above, all the charges to charge or discharge the compensation capacitor, that is, the current, are supplied from the compensation power supply circuit 403 using the voltage obtained by boosting the input voltage 104. The flowing current is twice as large as the value of the input power supply 104.
[0045]
That is, the voltage VGE_Hi, which is the compensation electrode line driving voltage 105, is represented by a calculation formula where the voltage of the input power supply 104 is VCC.
[0046]
(Equation 1)
VCC <VGE_Hi ≦ 2VCC
The relationship between the current IVGE flowing through the compensation electrode line driving voltage 105 and the current IVCC flowing through the input power supply 104 is expressed by a calculation formula.
[0047]
(Equation 2)
IVCC = 2IVGE
It becomes.
[0048]
Here, in the present embodiment, when the signal level of the compensation electrode line 118 reaches the positive side from the negative side, that is, when the compensation capacitance 112 is charged, the compensation capacitance 112 is set negative for a predetermined time of one horizontal period. Charging from the input power supply 104 to the potential VCC of the input power supply 104 from the potential VGE_Lo on the input side to the potential VCC of the input power supply 104 to the potential VGE_Hi on the positive side of the compensation electrode line 118 in the remaining period of one horizontal period. By performing charging with the output signal of the compensation power supply circuit 403, the compensation capacitor 112 is charged in two stages as shown by the positive polarity change waveform 202 in FIG.
[0049]
At this time, when the value of the current flowing through the compensation electrode line 118 is converted into the value of the current of the input power supply 104, the first period in which the compensation capacitor 112 is charged from the negative potential to the potential VCC of the input power supply 104 is equal to the current of the input power supply 104. While the current is one-time, the value of the input power supply 104 is twice as large in the second period in which the current is charged from the potential VCC of the input power supply 104 to the potential VGE_Hi on the positive side of the compensation capacitor 112. This is because the current flowing through the compensation power supply circuit 403 is generated by double boosting.
[0050]
When these are summed, the current value IVGE supplied from the input power supply 104 to the compensation capacitance line 118 has the following value according to each stage. That is, IVGE = IVCC in the first period, and IVGE = (1/2) IVCC in the second period.
[0051]
Here, assuming that the current value in the first period is I1 and the current value in the second period is I2, the total value of the current flowing to the input power supply 104 is (I1 + I2) × 2 in the related art. In the embodiment, (I1 + I2) × 2. Therefore, the difference between the two is (conventional current value) − (current value of the present embodiment) = I1, and in the present embodiment, the current for I1 can be suppressed as compared with the conventional example, and the power consumption is reduced. Becomes possible.
[0052]
Actually, since the loss always occurs in the booster circuit 401 of the power supply circuit 103, this current further increases. However, when the input power supply 104 is directly input, no loss occurs. , (I1 + I2) × 2 × (1 + loss rate), and in the present embodiment, (I1 + I2) × 2 × (1 + loss rate).
[0053]
Therefore, even when the loss due to the booster circuit 401 is considered, (conventional current value)-(current value of the present embodiment) = I1 (1 + 2 × the loss rate), and the current of I1 (1 + 2 × the loss rate) And power consumption can be reduced.
[0054]
Since the compensation power supply generating circuit 102 generally has a loss, the larger the loss, the greater the effect of further reducing power consumption.
[0055]
On the other hand, when the signal level of the compensation electrode line 118 reaches the potential on the negative side from the potential on the positive side, that is, when the compensation capacitance 112 is discharged, the potential of the compensation capacitance 112 is changed to the potential on the positive side for a predetermined period of one horizontal period. Discharge is performed directly from the input power supply 104 from VGE_Hi to the potential VCC of the input power supply 104, and from the potential VCC of the input power supply 104 to the potential VGE_Lo on the negative side of the compensation electrode line 118 during the remaining period of one horizontal period. By performing discharge with the output signal of the compensation power supply circuit 403, the compensation capacitor 112 is discharged in two stages as shown by the positive polarity change waveform 212 in FIG.
[0056]
Also at this time, the same calculation formula as when the compensation capacitor 12 is charged holds, the current of I1 (1 + 2 × the loss rate) can be suppressed, and the power consumption can be reduced.
[0057]
As described above, according to the present embodiment, in each of the charging period and the discharging period of the compensation capacitor 112, the output from the compensation power generation circuit 102 is not used in all the steps, but the input power By interposing a step of charging and discharging directly at 104, unnecessary power consumption can be suppressed, and the power consumption of the liquid crystal display device can be reduced.
[0058]
In the above embodiment, the input power supply 104 corresponds to the external power supply of the present invention, the compensation power supply generating circuit 102 corresponds to the compensation voltage generating means of the present invention, and the bypass line 104a corresponds to the bypass means of the present invention. Then, the compensation power supply switching circuit 100 corresponds to the selection output unit of the present invention. Further, the booster circuit 401 corresponds to the step-up / step-down means of the present invention, and the compensation power supply circuit 403 corresponds to the conversion means of the present invention.
[0059]
The positive potential VGE_Hi corresponds to the high compensation voltage of the present invention, the negative potential VGE_Lo corresponds to the low compensation voltage of the present invention, and the voltage VCC of the input power supply 104 is supplied from the external power supply of the present invention. Input voltage.
[0060]
The scan electrode drive circuit group 110 and the signal electrode drive circuit group 111 constitute a signal supply unit of the present invention, and include a liquid crystal layer 113, a pixel transistor 114, a pixel 115, a signal electrode line 116, a scan electrode line 117, and a compensation electrode line. The liquid crystal display panel of the present invention includes the liquid crystal layer 113, the pixel transistor 114, the pixel 115, and the counter electrode 119. The compensation capacitor 112 includes the liquid crystal display panel of the present invention. Of the compensation capacitor.
[0061]
However, the present invention is not limited to the above embodiment. Further, in the above-described embodiment, the liquid crystal display device has been described as an example, but may be realized as a power supply device for supplying a compensation voltage to a liquid crystal panel driven by independent CC. In this case, in the compensation power supply generation circuit 102, the compensation power supply circuit 403 generates the compensation power supply based on the signal from the output power supply circuit 402. However, the compensation power supply circuit 403 may generate the compensation power supply directly from the booster circuit 401.
[0062]
Also, the boost rate (or the step-down rate) has been described as being twice, but the step-up rate (or the step-down rate) may be any value as long as it is a numerical value of 1 or more.
[0063]
Further, as an example of the predetermined cycle of the present invention, the cycle in which the potential change between the positive side and the negative side of the compensation voltage is performed is one vertical synchronization period (1 V period), but is another cycle. You may. In addition, the period of the fluctuation of the potential between the positive side and the negative side of the compensation voltage itself is one horizontal synchronization period (1H period). However, as long as the process of directly charging and discharging with the voltage of the external power supply is interposed therebetween, Other periods may be used.
[0064]
【The invention's effect】
As described above, according to the present invention, the current loss in the booster circuit can be suppressed, and as a result, the power consumption can be suppressed.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a signal waveform of a liquid crystal display device according to an embodiment of the present invention. FIG. 4 is a diagram showing waveforms. FIG. 4 is a detailed configuration diagram of a power supply circuit of a conventional liquid crystal display device. FIG. 5 is an overall configuration diagram of a conventional liquid crystal display device.
REFERENCE SIGNS LIST 100 Compensation power supply switching circuit 101 Compensation power supply 102 Compensation power supply creation circuit 103 Power supply circuit 104 Input power supply 105 input to liquid crystal display device Compensation electrode line drive voltage 106 Compensation electrode drive power supply control signal 107 Power supply circuit control signal 108 Control signal generation circuit 109 Scan electrode signal electrode control signal 110 scan electrode drive circuit group 111 signal electrode drive circuit group 112 compensation capacitor 113 liquid crystal layer 114 liquid crystal panel pixel transistor 115 liquid crystal panel pixel 116 signal electrode line 117 scan electrode line 118 compensation electrode line 119 counter electrode 201 Conventional positive-polarity change waveform of potential VGEn 202 Conventional negative-polarity change waveform 211 of potential VGEn Positive-polarity change waveform 212 of potential VGEn of the present embodiment 212 Negative-polarity change waveform 301 of potential VGEn of this embodiment Eye signal waveform G1
302 Signal waveform G2 of the second line of the scanning electrode line 117
303 Signal Waveform Gn of nth Line of Scanning Electrode Line 117
311 Signal waveform GE1 of the first line of the compensation electrode line 118
312 Signal waveform GE2 of the second line of the compensation electrode line 118
313 Signal Waveform GEn of nth Line of Compensation Electrode Line 118
401 booster circuit 402 output power circuit 403 compensation power circuit 503 conventional power circuit

Claims

Scanning electrode lines and image electrode lines arranged in a matrix, and compensating electrode lines that are arranged corresponding to the scanning electrode lines and supply compensation voltages of two kinds of high and low voltages that fluctuate at a predetermined cycle; An independent CC (Charge-Coupling) driving liquid crystal display panel having at least a display element to which signals from scanning electrode lines and the image electrode lines are inputted and a compensation capacitor to which signals from the compensation electrode lines are inputted. A power supply device for supplying the compensation voltage,
Compensation voltage generation means for increasing and decreasing an input from an external power supply to generate the high and low compensation voltages;
Bypass means for directly outputting an input from the external power supply,
A selection output unit that receives an output from the compensation voltage generation unit and an output from the bypass unit, selects one of a high or low compensation voltage and an input from the external power supply, and outputs the selected one to the compensation power line. With
When the compensation voltage fluctuates from high to low, the selection output means performs selection so that the high compensation voltage, the input from the external power supply, and the low compensation voltage are output in this order,
The power supply device, wherein when the compensation voltage fluctuates from low to high, the selection output means selects so that the low compensation voltage, the input from the external power supply, and the high compensation voltage are output in this order.

The compensation voltage generating means includes:
Step-up / step-down means for stepping up or stepping down an input from the external voltage;
2. The power supply device according to claim 1, further comprising: a conversion unit configured to convert an output from the step-up / step-down unit to the two types of high and low compensation voltage signals that are output to the compensation power line.

Scanning electrode lines and image electrode lines arranged in a matrix, and compensating electrode lines that are arranged corresponding to the scanning electrode lines and supply compensation voltages of two kinds of high and low voltages that fluctuate at a predetermined cycle; An independent CC (Charge-Coupling) driving liquid crystal display panel having at least a display element to which signals from the scanning electrode lines and the image electrode lines are input and a compensation capacitor to which signals from the compensation electrode lines are input; ,
A signal supply unit that supplies a signal corresponding to each of the scan electrode line, the image electrode line, and the compensation electrode line,
3. A liquid crystal display device having the power supply device according to claim 1 or 2, wherein the signal supply means supplies a signal of the two kinds of high and low compensation voltages or an input from the external power supply to the compensation signal line.

Scanning electrode lines and image electrode lines arranged in a matrix, and compensating electrode lines that are arranged corresponding to the scanning electrode lines and supply compensation voltages of two kinds of high and low voltages that fluctuate at a predetermined cycle; An independent CC (Charge-Coupling) driving liquid crystal display panel having at least a display element to which signals from scanning electrode lines and the image electrode lines are inputted and a compensation capacitor to which signals from the compensation electrode lines are inputted. , A power supply method for supplying the compensation voltage,
A compensation voltage generation step of boosting and stepping down an input from an external power supply to generate the high and low compensation voltages;
A bypass step of directly outputting an input from the external power supply,
A selection output step of inputting the output from the compensation voltage generation step and the output from the bypass step, selecting either the high or low compensation voltage or the input from the external power supply, and outputting to the compensation power line. With
When the compensation voltage fluctuates from high to low, the selecting and outputting step selects such that the high compensation voltage, the input from the external power supply, and the low compensation voltage are output in this order,
When the compensation voltage varies from low to high, the selecting and outputting step includes a power supply method for selecting so that the low compensation voltage, the input from the external power supply, and the high compensation voltage are output in this order. .