JP3962309B2

JP3962309B2 - Color display device

Info

Publication number: JP3962309B2
Application number: JP2002307198A
Authority: JP
Inventors: 安彦尾崎
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2002-10-22
Filing date: 2002-10-22
Publication date: 2007-08-22
Anticipated expiration: 2022-10-22
Also published as: JP2004146936A

Description

【０００１】
【発明の属する技術分野】
この発明は、自発光素子を用いたカラーディスプレイ装置（例えば、プラズマディスプレイ装置、ＣＲＴディスプレイ装置、無機又は有機ＥＬディスプレイ装置）に関するものであり、特に良好な画像を得るための輝度及びホワイトバランスの補正技術に属する。
【０００２】
【従来の技術】
カラーディスプレイ装置においては、ディスプレイパネル内のＲ（赤色）、Ｇ（緑色）、Ｂ（青色）各画素要素が有する発光特性のばらつきにより、ホワイトバランスがばらつくため、工場出荷時においてホワイトバランス調整が行われている。
【０００３】
しかしながら、ホワイトバランス調整の終了後に、経時変化によりディスプレイパネルの発光部自体（ＣＲＴパネルあるいはプラズマディスプレイパネルでは蛍光体自体、ＥＬディスプレイパネルではＥＬ素子自体）が劣化すると、ホワイトバランスのずれ及び輝度の低下が生じると言う問題点がある。
【０００４】
従来のプラズマディスプレイ装置においては、本問題点を解決する方法として、プラズマディスプレイパネル内に光センサを設け、予備放電電極の発光を上記光センサで測定することによりホワイトバランスを補正する方法が、提案されている(例えば、特許文献１参照)。しかしながら、本方法においては、予備放電電極の発光を利用しており、光センサ出力から得られる情報が表示画面の劣化状況を反映していない場合があり、そのため補正が十分でないと言う問題点が生じ得る。
【０００５】
又、従来のプロジェクションテレビにおける表示装置は、オーバースキャン部分を測定している（例えば、特許文献２参照）。しかしながら、本方法においては、オーバースキャン部分の表示から得られる情報が表示画面の劣化状況を反映していない場合があり、そのため補正が十分でないと言う同様な問題点が生じ得る。
【０００６】
このため、両特許文献１，２に提案された従来技術は何れも本問題点の有効な解決策とは成り得ないのである。
【０００７】
【特許文献１】
特開平８−９４１５号公報（第２−４頁、第２図）
【特許文献２】
特開平９−３７２８１号公報（第２−３頁、第１図）
【０００８】
【発明が解決しようとする課題】
上記の通り、自発光素子を用いた従来のカラーディスプレイ装置においては、経時変化によりディスプレイパネル内の蛍光体自体が劣化すると、ホワイトバランスのずれ及び輝度の低下が生じると言う問題点が、存在している。しかも、既述の従来技術は、表示装置の輝度低下を測定するに際して、表示画面の経時劣化の状況を正しく測定出来ていないと言う問題点を有している。
【０００９】
この発明は、斯かる懸案事項を解消するためになされたものであり、その主たる目的は、経時変化による表示画面の劣化を考慮に入れた上で、ホワイトバランスの良好な画像を得ることが出来る補正技術を提供することにある。更に、本発明の副次的目的は、経時変化による表示画面の劣化を考慮に入れた上で、輝度及びホワイトバランスの良好な画像を得ることが出来る補正技術を提供することにある。
【００１０】
【課題を解決するための手段】
この発明の主題は、入力３原色信号に対してガンマ補正を行い、補正後の被補正３原色信号を出力するガンマ補正手段と、前記ガンマ補正手段の前記被補正３原色信号に基づき前記３原色に関する第１駆動信号を生成し、前記第１駆動信号を出力する画像表示部駆動手段と、前記第１駆動信号に基づき、前記入力３原色信号によって与えられる第１画像を表示する画像表示部と、前記画像表示部の第１発光特性と同一の第２発光特性及び前記画像表示部の第１経時変化特性と同一の第２経時変化特性を有し、通常動作期間においては第２画像を表示する一方、補正期間においては第３画像を表示する測定用表示部と、前記ガンマ補正手段の前記被補正３原色信号のそれぞれに対して１画面当りに関する平均化処理を行って、前記入力３原色信号それぞれの平均の明るさを与える被平均化３原色信号を生成し、前記被平均化３原色信号を出力する平均の明るさ算出手段と、少なくとも１種類の測定用１画面を与える３原色テストパターン信号を保有すると共に、前記３原色テストパターン信号を出力するテストパターン発生手段と、第１制御信号のレベルに応じて、前記平均の明るさ算出手段から出力された前記被平均化３原色信号を出力する第１の接続、または前記テストパターン発生手段から出力された前記３原色テストパターン信号を出力する第２の接続とを切替える切換手段と、前記切換手段の出力信号に基づき前記３原色に関する第２駆動信号を生成し、前記第２駆動信号を出力する測定用表示部駆動手段と、前記通常動作期間においては前記切換手段に対して前記第１接続を指令する第１レベルを有する一方、前記補正期間においては前記切換手段に対して前記第２接続を指令する第２レベルを有する前記第１制御信号を生成して出力する切換手段制御部と、前記測定用表示部の表示面に対向配置されており、前記補正期間において前記測定用表示部が表示する、測定用基本パターンである前記第３画像の前記３原色の明るさを検出して、被検出３原色明るさ信号を出力する光センサと、前記測定用表示部駆動手段において前記３原色テストパターン信号より生成される前記第２駆動信号のレベルデータを保有しており、前記レベルデータ及び前記被検出３原色明るさ信号に基づいて、少なくとも前記第１画像のホワイトバランスを補正するために必要な前記第１駆動信号の補正量に相当する変換テーブルデータを生成し、前記変換テーブルデータを第２制御信号として出力するガンマ補正制御部とを備え、前記ガンマ補正手段は、前記第２制御信号が与える前記変換テーブルデータに基づき前記ガンマ補正を行うカラーディスプレイ装置であって、前記ガンマ補正制御部は、（ａ）前記レベルデータ及び前記被検出３原色明るさ信号に基づいて、前記３原色に関する、前記第２駆動信号と前記第３画像における明るさとの関係を示す近似曲線を与えるデータを生成する手段と、（ｂ）前記第１画像における前記３原色それぞれの明るさの比率を所定の比率とするために必要な、前記３原色の内の基準色に関する前記第１駆動信号の第１レベルに対する他の２色に関する前記第１駆動信号の第２及び第３レベルを与える暫定的変換テーブルデータを、前記近似曲線データに基づいて生成する手段と、（ｃ）前記第１駆動信号の前記第１レベルに対して、（１）前記基準色に関しては前記第１駆動信号の前記第１レベル自体を前記第１駆動信号の第１補正レベルとして与え、（２）前記他の２色の一方に関しては前記第１駆動信号の前記第１レベルと前記第２レベルとで規定され且つ前記第１及び第２レベルを除く範囲内のレベルを前記第１駆動信号の第２補正レベルとして与え、且つ、（３）前記他の２色の他方に関しては前記第１駆動信号の前記第１レベルと前記第３レベルとで規定され且つ前記第１及び第３レベルを除く範囲内のレベルを前記第１駆動信号の第３補正レベルとして与える制限補正テーブルデータに基づき、前記変換テーブルデータを決定する手段とを更に有することを特徴とする。
【００１１】
【発明の実施の形態】
（実施の形態１）
本実施の形態においては、便宜上、自発光素子を有するカラーディスプレイ装置の一例として、プラズマディスプレイ装置が採用されている。以下、図面に基づき、本実施の形態を詳述する。
【００１２】
図１は、本実施の形態に係るプラズマディスプレイ装置のプラズマディスプレイパネル（以下、ＰＤＰと称す：ディスプレイパネルに該当）を前面ないしは表示面側から眺めた際の平面図である。図１に示す様に、ＰＤＰのパネル中央部には画像表示部１が配設されており、同部１の周辺領域は、画像を表示しない表示パネル周辺部２を成す。但し、図１の紙面上方から見て表示パネル周辺部２内の右側領域には、測定用表示部３が配設されている。そして、画像表示部１と測定用表示部３とは、共に同一工程で製造されており、しかも、同一構造を有する。加えて、両表示部１，３の駆動回路（後述する図３の回路１９，２０）もまた、同一の回路構成を備えている。そのため、画像表示部１の発光特性は測定用表示部３のそれと同一であり、且つ、画像表示部１の経時変化特性もまた測定用表示部３のそれと同一である。尚、ここで「同一」と言うときには、「略同一」と言う概念もそこに含まれるのであり、その意味では、「同一」と言う用語は、ある程度の許容幅（広がり）を持った概念である。
【００１３】
図２は、図１に示すＰＤＰを有するプラズマディスプレイ装置において、当該ＰＤＰをその上部から（図１に示す矢印方向Ａ１から）眺めた際の透視平面図である。図２においては、図１に示す構成要素に相当する部分には、同一の符号が付されている。図２に示されている様に、ＰＤＰの本体を成す表示パネル４の表示面４Ｓ側には、画像表示部１と測定用表示部３とが形成されており、測定用表示部３の前面ないしは表示面３Ｓ上に、光センサ５が対向配置されている。しかも、光センサ５の周囲を完全に取り囲む様に、遮光カバー６が表示面３Ｓの周囲上に配置されている。この構造により、測定用表示部３から発せられる光は遮光カバー６によって遮光され、外部に漏れることはない。
【００１４】
図３は、本実施の形態１に係るプラズマディスプレイ装置の回路構成を模式的に示すブロック図である。図３においても、図１及び図２に示す構成要素に相当する部分には、同一の符号が付されている。
【００１５】
図３に示されている様に、Ｒ信号入力端子１０はＲ（赤色）信号ＶＲを受信し、Ｇ信号入力端子１１はＧ（緑色）信号ＶＧを受信し、Ｂ信号入力端子１２はＢ（青色）信号ＶＢを受信する。ここでは、上記入力信号ＶＲ、ＶＧ及びＶＢを、Ｒ（赤色）、Ｇ（緑色）及びＢ（青色）から成る３原色の「入力３原色信号」と総称すると共に、３つの入力端子１０，１１，１２もまた「入力端子」と総称する。
【００１６】
又、Ｒガンマ補正回路１３は、Ｒ信号入力端子１０に接続された入力端、ＣＰＵ２１の出力端２１ＯＴに接続されており第２制御信号ＶＣＴ２を受信するための制御端子、及び出力端とを有し、Ｒ信号ＶＲに対して既知のガンマ補正を行い、補正後のＲ信号（被補正Ｒ信号）Ｖ１３Ｒをその出力端より出力する。同じく、Ｇガンマ補正回路１４は、Ｇ信号入力端子１１に接続された入力端、ＣＰＵ２１の出力端２１ＯＴに接続されており第２制御信号ＶＣＴ２を受信するための制御端子、及び出力端とを有し、Ｇ信号ＶＧに対して既知のガンマ補正を行い、補正後のＧ信号（被補正Ｇ信号）Ｖ１４Ｇをその出力端より出力する。同様に、Ｂガンマ補正回路１５は、Ｂ信号入力端子１２に接続された入力端、ＣＰＵ２１の出力端２１ＯＴに接続されており第２制御信号ＶＣＴ２を受信するための制御端子、及び出力端とを有し、Ｂ信号ＶＢに対して既知のガンマ補正を行い、補正後のＢ信号（被補正Ｂ信号）Ｖ１５Ｂをその出力端より出力する。ここでは、３原色の上記補正回路１３、１４及び１５を「ガンマ補正回路」と総称すると共に、３原色の上記被補正信号Ｖ１３Ｒ，Ｖ１４Ｇ，Ｖ１５Ｂを「被補正３原色信号」と総称する。
【００１７】
又、画像表示部駆動回路２０は、ガンマ補正回路（１３，１４，１５）の出力端に接続された入力端及び出力端とを有し、被補正３原色信号（Ｖ１３Ｒ，Ｖ１４Ｇ，Ｖ１５Ｂ）に基づき３原色に関する第１駆動信号Ｖ２０Ｒ，Ｖ２０Ｇ，Ｖ２０Ｂを生成し、第１駆動信号Ｖ２０Ｒ，Ｖ２０Ｇ，Ｖ２０Ｂをその出力端より出力する。そして、画像表示部１は、画像表示部駆動回路２０の出力端に接続された入力端を有しており、第１駆動信号Ｖ２０Ｒ，Ｖ２０Ｇ，Ｖ２０Ｂに基づき、入力３原色信号ＶＲ，ＶＧ，ＶＢによって与えられる本来表示すべき画像である第１画像を表示する。
【００１８】
これに対して、本装置の核心部であるホワイトバランス補正回路系は、次の各要素１６−１９，３，５及び２１より構成される。以下に、ホワイトバランス補正回路系の各構成要素について記載する。
【００１９】
先ず、テストパターン発生回路１６は、例えばＲＯＭより成る固有画面データ格納部であり、出力端、及びＣＰＵ２１より発せられるアドレス信号ＶＡを受信する受信端を有する。そして、同回路１６は、少なくとも１種類の測定用１画面（固定画面）を与える３原色テストパターン信号Ｖ１６Ｒ、Ｖ１６Ｇ、及びＶ１６Ｂを保有しており、アドレス信号ＶＡの読出しタイミングに応じて３原色テストパターン信号Ｖ１６Ｒ、Ｖ１６Ｇ、及びＶ１６Ｂをその出力端より出力する。尚、本実施の形態では、説明の便宜上、同回路１６は、３種類の測定用１画面（固定画面）をそれぞれ与える３種類の３原色テストパターン信号Ｖ１６Ｒ、Ｖ１６Ｇ、及びＶ１６Ｂ（各種の３原色テストパターン信号をそれぞれグレー信号Ｋ１，Ｋ２，Ｋ３と称す）を保有している。
【００２０】
又、平均の明るさ生成回路１７は、ガンマ補正回路（１３，１４，１５）の出力端に接続された入力端及び出力端を有しており、被補正３原色信号（Ｖ１３Ｒ，Ｖ１４Ｇ，Ｖ１５Ｂ）のそれぞれに対して１画面当りに関する平均化処理を行って、入力３原色信号（ＶＲ，ＶＧ，ＶＢ）それぞれの平均の明るさを与える被平均化３原色信号Ｖ１７Ｒ、Ｖ１７Ｇ、及びＶ１７Ｂを生成し、被平均化３原色信号Ｖ１７Ｒ、Ｖ１７Ｇ、及びＶ１７Ｂをその出力端より出力する。
【００２１】
又、切換回路１８は、平均の明るさ生成回路１７の出力端に接続された第１入力端１８ＩＴ１と、テストパターン発生回路１６の出力端に接続された第２入力端１８ＩＴ２と、ＣＰＵ２１内の切換制御部から発する第１制御信号ＶＣＴ１を受信するための制御端と、出力端１８ＯＴとを有しており、第１制御信号ＶＣＴ１のレベルに応じて、第１入力端１８ＩＴ１と出力端１８ＯＴとの第１接続と、第２入力端１８ＩＴ２と出力端１８ＯＴとの第２接続とを、切り換える。
【００２２】
又、測定用表示部駆動回路１９は、切換回路１８の出力端に接続された入力端と、測定用表示部３の入力端に接続された出力端とを有しており、切換回路から発せられる３原色に関する出力信号Ｖ１８Ｒ、Ｖ１８Ｇ、及びＶ１８Ｂに基づき、３原色に関する第２駆動信号Ｖ１９Ｒ、Ｖ１９Ｇ、及びＶ１９Ｂを生成し、第２駆動信号Ｖ１９Ｒ、Ｖ１９Ｇ、及びＶ１９Ｂをその出力端より出力する。
【００２３】
ここで、ＣＰＵ２１内の一機能回路部である切換回路制御部は、（ｉ）ホワイトバランス補正を一切行わない通常動作期間においては、上記第１接続を指令する第１レベル（例えばＬレベル）を有する第１制御信号ＶＣＴ１を、その出力端より切換回路１８に対して出力する一方、（ｉｉ）通常動作期間後の、換言すれば、ある通常動作期間と次の通常動作期間との間の、ホワイトバランス補正を行う補正期間においては、上記第２接続を指令する第２レベル（例えばＨレベル）を有する第１制御信号ＶＣＴ１を、その出力端より切換回路１８に対して出力する。その結果、測定用表示部３は、（ｉ）通常動作期間においては、第１画像の明るさを１画面に渡って平均化した明るさを有する第２画像を第１画像の表示と同時に表示し続ける一方、（ｉｉ）通常動作期間と比較して極めて短期間の補正期間においては、各グレー信号Ｋ１，Ｋ２，Ｋ３によって与えられる測定用１画面（固定画面）である３種の第３画像を順次に表示する。従って、両表示部１，３の第１及び第２発光特性は互いに同一であり、且つ、両表示部１，３の第１及び第２経時変化特性も互いに同一である上に、第２画像は第１画像の平均的明るさを有する画像とされているので、通常動作期間中における実際の両表示部１，３の表示特性の経時劣化は互いにほぼ等しいとみなすことが可能である。加えて、補正期間においては、成る程に、測定用表示部３は、第１画像とは何の関係も無い固定画像としての第３画像を表示しているけれども、当該補正期間は固定画面の第３画像の明るさを光センサ５で以って検出するのに要する時間に相当しており、その検出時間は通常動作期間と比較して相対的に極めて短い時間であると、みなし得るので、補正期間の介在によっては、両表示部１，３の表示特性経時劣化レベル間に差異は何等生じないものと、評価可能である。この点に関する発想（着眼点）が、本実施の形態の技術的思想を支えるバックボーンである。
【００２４】
尚、ＣＰＵ２１内の切換回路制御部は、ユーザーによる外部からの補正指令に応じて第２レベルの第１制御信号ＶＣＴ１を発する様にしても良いし、あるいは、ＣＰＵ２１内部にタイマを有しておき、当該タイマの時間が予め定められた補正時になった際に切換回路制御部が第２レベルの第１制御信号ＶＣＴ１を発することとしても良い。
【００２５】
又、光センサ５は、図２の記載において既述した様に測定用表示部３の表示面３Ｓに対向配置されており、少なくとも、補正期間において測定用表示部３が表示する第３画像（測定用基本パターン）の３原色の明るさを検出して、被検出３原色明るさ信号Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂをその出力端より出力する。但し、本実施の形態においては、光センサ５は、第３画像の明るさ検出のみならず、通常動作モードでの第２画像の明るさ検出をも行うものとしており、ＣＰＵ２１は、光センサ５の出力信号Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂが第３画像の明るさ検出信号を与えるときにのみ（換言すれば、第２レベルの第１制御信号ＶＣＴ１を生成・出力している補正期間のみ）、出力信号Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂを受信・入力するものとしている。あるいは、この構成に代えて、図３に破線で示す様に、ＣＰＵ２１は、第２レベルの第１制御信号ＶＣＴ１を、光センサ５のオン・オフ制御信号として更に光センサ５に出力することによって、光センサ５は補正期間においてのみ検出動作を行うこととしても良い。
【００２６】
ＣＰＵ２１は、当該ホワイトバランス補正回路系の中核要素であり、既述の切換回路制御部としての動作を担うのみならず、次のガンマ補正制御部に代表される様な様々な機能を呈する。特に、ＣＰＵ２１内のガンマ補正制御部について述べると、次の通りである。
【００２７】
即ち、ガンマ補正制御部は、光センサ５の出力端に接続された入力端及びガンマ補正回路（１３，１４，１５）の制御端に接続された出力端を有し、測定用表示部駆動回路１９において３原色テストパターン信号Ｖ１６Ｒ，Ｖ１６Ｇ，Ｖ１６Ｂより生成される第２駆動信号Ｖ１９Ｒ，Ｖ１９Ｇ，Ｖ１９Ｂのレベルデータを保有している。その上で、同部は、上記レベルデータ及び補正期間において受信する被検出３原色明るさ信号Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂに基づいて、第１画像のホワイトバランスを補正するために必要な第１駆動信号Ｖ２０Ｒ，Ｖ２０Ｇ，Ｖ２０Ｂの補正量に相当する変換テーブルデータを生成し、当該変換テーブルデータを第２制御信号ＶＣＴ２としてその出力端より出力する。その結果、各ガンマ補正回路１３，１４，１５は、第２制御信号ＶＣＴ２の受信以後、第２制御信号ＶＣＴ２が与える変換テーブルデータに基づき、ガンマ補正を行う。
【００２８】
次に、図３の装置の動作を、ＣＰＵ２１における動作・機能を示すフローチャートである図５を適宜参照しつつ、且つ、その他の図面をも参照しつつ、詳述する。
【００２９】
先ず、Ｒ信号入力端子１０、Ｇ信号入力端子１１、及びＢ信号入力端子１２は、それぞれＲ信号ＶＲ，Ｇ信号ＶＧ，及びＢ信号ＶＢを受信し、受信した入力色信号を対応する色のガンマ補正回路１３−１５に出力する。その結果、Ｒ信号ＶＲ，Ｇ信号ＶＧ，及びＢ信号ＶＢは、それぞれ対応する色のガンマ補正回路１３，１４，及び１５に入力される。そして、各ガンマ補正回路１３，１４，１５は、各回路１３−１５内に予め設定されているガンマ補正用の入力―出力変換テーブルデータに基づき、所望の輝度及びホワイトバランスを有する良好な第１画像表示が画像表示部１において得られる様に、入力３原色信号（ＶＲ，ＶＧ，ＶＢ）の内で対応する色信号に対して既知のガンマ補正を施す。その上で、各ガンマ補正回路１３，１４，及び１５は、補正後の被補正Ｒ信号Ｖ１３Ｒ，被補正Ｇ信号Ｖ１４Ｇ，及び被補正Ｂ信号Ｖ１５Ｂを、画像表示部駆動回路２０及び平均の明るさ生成回路（実質的には第２画像信号を生成する部分）１７に出力する。
【００３０】
その結果、一方の画像表示部駆動回路２０は、受信した被補正３原色信号Ｖ１３Ｒ，Ｖ１４Ｇ，及びＶ１５Ｂを、第１画像の表示に適したデータ形式の第１駆動信号Ｖ２０Ｒ，Ｖ２０Ｇ，及びＶ２０Ｂに変換した上で、生成後の３原色それぞれの第１駆動信号Ｖ２０Ｒ，Ｖ２０Ｇ，及びＶ２０ＢをＰＤＰ内の画像表示部１の電極（図示せず）に印加し、画像表示部１は第１画像を表示する。
【００３１】
他方の平均の明るさ生成回路１７は、受信した被補正３原色信号Ｖ１３Ｒ，Ｖ１４Ｇ，及びＶ１５Ｂそれぞれの平均の明るさを算出する処理を行う。即ち、平均の明るさ生成回路１７は、１画面分の各被補正３原色信号Ｖ１３Ｒ，Ｖ１４Ｇ，及びＶ１５Ｂのレベルに対して平均化処理を実行して、各色毎に、平均的な明るさのレベルを与える１画面平均信号を生成する。更に、同回路１７は、各色の１画面平均信号をローパスフィルタ（図示せず）に通すことによって、各１画面平均信号を一定時間平均化する。その結果得られる信号が、第１画像に対して平均的な明るさ（光量）を呈する第２画像を形成する出力信号Ｖ１７Ｒ，Ｖ１７Ｇ，Ｖ１７Ｂである。尚、各色に関する上記１画面平均信号を以って出力信号Ｖ１７Ｒ，Ｖ１７Ｇ，Ｖ１７Ｂとしても良い（つまり、ローパスフィルタ処理を行わない）。
【００３２】
その様な平均の明るさ生成回路１７によって算出されるＧ色に関する出力信号Ｖ１７Ｇを、図４のグラフに示す。図４中、横軸は時間を、縦軸は平均化処理された出力信号Ｖ１７Ｇの大きさ（レベル）を示す。そして、図４中の破線で示される曲線２６がＧ（緑）に関する１画面平均信号であり、実線で示される曲線２５が、Ｇの１画面平均信号２５を更に一定時間だけ平均化処理して得られる出力信号Ｖ１７Ｇである。
【００３３】
そして、本回路１７は、上述の明るさ平均化処理を行った後に、３原色それぞれに関する出力信号Ｖ１７Ｒ，Ｖ１７Ｇ（図４の曲線２５相当），Ｖ１７Ｂを、切換回路１８の第１入力端１８ＩＴ１に送信する。
【００３４】
（Ａ）以下においては、先ず、通常動作期間（通常動作モード）における動作を記載する。
【００３５】
ＣＰＵ２１は、補正期間の開始指令を検出しない限りは、図３の本装置は通常動作モードにあるものと判断して、第１レベルの第１制御信号ＶＣＴ１を切換回路１８の制御端に出力し続ける（図５のステップＳ１）。その結果、通常動作モードにおいては、切換回路１８は第１接続を実現し続け、従って、平均の明るさ生成回路１７の出力信号Ｖ１７Ｒ，Ｖ１７Ｇ，Ｖ１７Ｂを通す。その結果、切換回路１８を通過した各色の出力信号Ｖ１７Ｒ，Ｖ１７Ｇ，Ｖ１７Ｂは測定用表示部駆動回路１９に入力され、同回路１９は、入力した各色の出力信号Ｖ１７Ｒ，Ｖ１７Ｇ，Ｖ１７Ｂを、第２画像の表示に適したデータ形式の第２駆動信号Ｖ１９Ｒ，Ｖ１９Ｇ，Ｖ１９Ｂを生成して測定用表示部３の電極（図示せず）に印加し、これにより、測定用表示部３は、画像表示部１の第１画像の明るさと対比して、その平均的な明るさを呈する第２画像を表示する。
【００３６】
この様に、通常動作期間においては、測定用表示部３は常に画像表示部１の表示画像に対して平均的な明るさを有する第２画像の表示を行うので、偏りのない平均的な画像表示部１における経時変化を測定用表示部３で実現可能としている。即ち、通常動作期間中における、画像表示部１の経時変化と測定用表示部３の経時変化とはほぼ同一であると、みなし得る。
【００３７】
（Ｂ）次に、通常動作期間に引き続く補正期間における動作について記載する。
【００３８】
本ディスプレイ装置の工場出荷時点から、ある時間経過した時点においては、測定用表示部３の入力信号（第２駆動信号）に対する各色毎の明るさの表示特性は、相互に相違している。この明るさ表示特性の相対的なずれ量は、測定用表示部３における表示特性の経時変化に起因するものであるので、同様の相対的なずれ量は画像表示部１に関してもほぼ同様に妥当する。即ち、３原色中の基準色に関する入力信号のあるレベルに関して各色の明るさのレベルを比較すると、他の２色中、一方の明るさは基準色のそれよりも明るく（あるいは暗く）、他方の色の明るさは基準色のそれよりも更に明るくなる（あるいは更に暗くなる）。このため、使用時における３原色の輝度の比率は工場出荷時における３原色の輝度の調整済み比率とは異なったものとなっており、使用時の白色光は好ましくない色温度の白色となっている。そこで、工場出荷時の調整値からずれてしまっている画像表示部１におけるホワイトバランスを、測定用表示部３における第３画像のホワイトバランスの調整ないしは補正処理を通じて、好ましいレベルに補正する必要性が生じる。既述の通り、通常動作期間においては両表示部１，３の表示特性の経時変化は同等とみなすことが出来、しかも、補正期間における光センサ５による明るさ検出期間は相対的に見て極めて短く無視し得る時間であるため、補正期間においても両表示部１，３の表示特性の経時変化に齟齬は生じていないと、みなし得る。従って、測定用表示部３における第３画像のホワイトバランスの補正処理は、画像表示部１におけるホワイトバランスの補正処理と等価である。
【００３９】
（Ｂ−１）通常動作期間における上記状態の下で、例えば、本装置の電源投入後からある程度の時間が経過した時に、あるいは本装置の電源オフ時に、あるいは、本装置がテレビジョンである場合においてそのチャンネルを切り換えることによって入力３原色信号が変更された時に、或いは、画面に画像が表示されていない時に、ＣＰＵ２１は、補正期間の開始時であると判断して、第２レベルを有する第１制御信号ＶＣＴ１を切換回路１８の制御端に印加する（図５のステップＳ２）。その結果、切換回路１８は第１接続から第２接続へと接続関係を切換える。そして、ＣＰＵ２１は、データ読出し制御信号たるアドレス信号ＶＡをテストパターン発生回路１６の制御端に出力し、その結果、同回路１６は、保有する３種の３原色テストパターン信号Ｖ１６Ｒ，Ｖ１６Ｇ，Ｖ１６Ｂを１画面毎に順次に切換回路１８側に出力する。尚、最初の１固定画面を与える３原色テストパターン信号（第１グレー信号Ｋ１）の出力タイミングに関しては、当該第１グレー信号Ｋ１を読み出すためのアドレス信号ＶＡを、第１制御信号ＶＣＴ１の第１レベルから第２レベルへの変更前の時点で、ＣＰＵ２１は生成・出力しても良い。切換回路１８内の切換動作により、Ｒ、Ｇ、Ｂ各色のテストパターン信号Ｖ１６Ｒ，Ｖ１６Ｇ，Ｖ１６Ｂが測定用表示部駆動回路１９に入力され、同回路１９は、１固定画面たるテストパターンを表示するのに適したデータ形式の第２駆動信号Ｖ１９Ｒ，Ｖ１９Ｇ，Ｖ１９Ｂを生成・出力する。これにより、測定用表示部３は、第１グレー信号Ｋ１によって与えられる第１番目のテストパターンの第３画像（固定画面）を表示し、即座に光センサ５は第１番目のテストパターンにおける各色の明るさ（光量）を検出して、その検出データＶ５Ｒ，Ｖ５Ｇ，Ｖ５ＢをＣＰＵ２１に送信する。ＣＰＵ２１は同信号Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂを受信・取得する。引き続いて、ＣＰＵ２１は、再度アドレス信号ＶＡをテストパターン回路１６に送信して同回路１６から第２グレー信号Ｋ２を読出し、第２グレー信号Ｋ２によって与えられる第２番目のテストパターンの第３画像（固定画面）を測定用表示部３において表示させ、光センサ３から第２番目のテストパターンにおける各色の明るさ（光量）データを取得する。更に、ＣＰＵ２１は、アドレス信号ＶＡをテストパターン回路１６に送信して同回路１６から第３グレー信号Ｋ３を読出し、第３グレー信号Ｋ３によって与えられる第３番目のテストパターンの第３画像（固定画面）を測定用表示部３において表示させ、光センサ３から第３番目のテストパターンにおける各色の明るさ（光量）データを取得する。ここで再度述べると、テストパターンは、画像表示部１の入力信号（第１駆動信号）に対する明るさの表示特性を求めるための基本パターンである（グレー信号Ｋ１，Ｋ２，Ｋ３）。勿論、テストパターンの数は任意であり、少なくとも１種類のテストパターンさせ保有されていれば、理論的には次に記載する近似曲線及び変換曲線を求めることは可能である。
【００４０】
そして、ＣＰＵ２１は、全てのテストパターンにおける各色の明るさ（光量）データの取得完了後に、第１制御信号ＶＣＴ１のレベルを第１レベルに戻す。
【００４１】
（Ｂ−２）次に、ＣＰＵ２１（ガンマ補正制御部）は、その内部に保有している上記レベルデータ、及び、光センサ５より取得した被検出３原色明るさ信号Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂに基づいて、３原色の各色に関する、第２駆動信号と第３画像における明るさとの関係を示す近似曲線を与えるデータを生成する（図５のステップＳ３）。以下では、記載を簡単化すると言う見地から、Ｒ，Ｇ，Ｂ各色の明るさが等しいときに、即ち、Ｒ，Ｇ，Ｂ各色の輝度の比率が１：１：１のときに、ホワイトバランスが良好になっているものとする（一般的には、Ｒ，Ｇ，Ｂ各色の輝度の比率が所定の比率を与えるときに、ホワイトバランスは良好であると言える）。この点は、後述する全ての変形例、その修正例及び他の実施の形態においても、妥当する。
【００４２】
図６は、ＣＰＵ２１によって生成された近似曲線データの一例を、即ち、工場出荷時からある時間だけ経過した時点における、測定用表示部３の入力信号に対する明るさの表示特性を与える近似曲線を示している。図６に示す通り、Ｒ，Ｇ，Ｂ各色の入力信号Ｖ１９Ｒ，Ｖ１９Ｇ，Ｖ１９Ｂに対する明るさの特性が相互にずれていることが理解される。工場出荷時においては、Ｒ，Ｇ、Ｂ各色の明るさ特性は同一になる様に調整されているので、３色の明るさレベルは同じ線上にあるが、その後の経時変化により、Ｂ（青）の明るさが３色の中で最も暗くなり、その次にＧ（緑）の明るさが暗い状態となっている。例えば、図６の横軸のレベルデータが入力信号Ｋ３のときには、（Ｒの明るさＲ３）＞（Ｇの明るさＧ３）＞（Ｂの明るさＢ３）と言う大小関係が得られる。この結果、第３画像及び第１画像のホワイトバランスに関しては、白色光が赤く染まった状態となっており（色温度の低下）、好ましくない画像が表示されている。
【００４３】
（Ｂ−３）次に、ＣＰＵ２１（ガンマ補正制御部）は、第１画像、従って第３画像における３原色それぞれの明るさの比率を所定の比率（ここでは１：１：１）とするために必要な、３原色の内の基準色（図６の例ではＢ（青色））に関する第１駆動信号の第１レベル（図６の例では横軸のレベルＫ１，Ｋ２，Ｋ３に該当）に対する、他の２色（図６の例ではＲ（赤色）及びＧ（緑色））に関する第２駆動信号の第２及び第３レベルを与える変換テーブルデータを、上記近似曲線データに基づいて生成する（図５のステップＳ４）。
【００４４】
図６に則してより具体的に述べると、ＣＰＵ２１は、ホワイトバランスを良好にするために、バランスの崩れたＲ、Ｇ、Ｂ各色の明るさを、現補正期間において一番暗いＢの明るさに合致する様に、ガンマ補正回路１３，１４，１５で使用する、Ｒ、Ｇ、Ｂ各色の入力信号を変換するための変換テーブルを作成する。即ち、図６の一例によれば、ＣＰＵ２１は、図６の近似曲線より、入力信号Ｋ３における基準色Ｂ（青色）の明るさ（第１レベル）Ｂ３を与える他の２色Ｒ、Ｇの入力信号（第２及び第３レベル）Ｋ３Ｒ及びＫ３Ｇを決定する。そして、算出した第２駆動信号の第２及び第３レベルＫ３Ｒ及びＫ３Ｂを、図７に示すガンマ補正回路の入力信号と出力信号との変換図に、プロットする。同様に、ＣＰＵ２１は、基準色Ｂに関する第２駆動信号の第１レベルＫ１及びＫ２のそれぞれに対する、他の２色Ｒ、Ｇの第２駆動信号の第２及び第３レベル（Ｋ１Ｒ，Ｋ１Ｇ）及び（Ｋ２Ｒ，Ｋ２Ｇ）をも図６の近似曲線から算出して、得られた第２及び第３レベル（Ｋ１Ｒ，Ｋ１Ｇ）、及び別の第２及び第３レベル（Ｋ２Ｒ，Ｋ２Ｇ）を図７に示す様にプロットすることで、これらの算出点から変換曲線を求める。以上の一連の処理により得られた、図７に例示する変換曲線が、変換テーブルデータを成すのである。
【００４５】
尚、ここでは好ましい態様として基準色をＢ（青色）と設定しているが、これに代えて、Ｒ（赤色）及びＧ（緑色）の何れか一方を基準色に設定しても良い。
【００４６】
（Ｂ−４）その後、ＣＰＵ２１は、求められた変換テーブルデータを第２制御信号ＶＣＴ２として各色のガンマ補正回路１３，１４，１５に送信する（図５のステップＳ５）。
【００４７】
その結果、ガンマ補正回路１３，１４，１５の各々は、第２制御信号ＶＣＴ２が与える対応する色の変換テーブルデータを受け取り、以後、当該変換テーブルデータに基づいて、入力信号から出力信号への変換（ガンマ補正）を行う。
【００４８】
その結果、本実施の形態によれば、画像表示部１における表示特性の経時変化に伴う劣化状況を的確に反映させつつ、換言すれば、当該劣化状況を正しく測定しつつ、所定のホワイトバランスを有する良好な画像表示を得ることが出来る。更に述べれば、本実施の形態においては、測定用表示部３は、画像表示部１における経時劣化を考慮した実際の表示画像（第１画像）に極めて近い画像の表示を実現し得るので、その様な測定用表示部３において実施される表示画像（第３画像）の明るさ検出は、実際の表示画像（第１画像）の、ホワイトバランスを決定付けるＲ，Ｇ，Ｂ各色の輝度の高精度測定と等価である。
【００４９】
（変形例１）
本変形例は実施の形態１の改善技術に関するものであり、当該技術の要旨は、ＣＰＵ２１が算出した変換テーブルデータを「暫定的な変換テーブルデータ」とした上で、この暫定的な変換テーブルデータが与える補正量に制限を設ける点にある。即ち、ＣＰＵ２１（ガンマ補正制御部）は、上記暫定的変換テーブルデータを用いて、▲１▼３原色中の基準色に関しては第２駆動信号（従って第１駆動信号）の第１レベル自体を第２駆動信号（従って第１駆動信号）の第１補正レベルとして与え（補正量の制限なし）、▲２▼他の２色の一方に関しては、第２駆動信号（従って第１駆動信号）の第１レベルと第２レベルとで規定され且つ第１及び第２レベルを除く範囲内のレベルを第２駆動信号（従って第１駆動信号）の第２補正レベルとして与えると共に、▲３▼他の２色の他方に関しては、第２駆動信号（従って第１駆動信号）の第１レベルと第３レベルとで規定され且つ第１及び第３レベルを除く範囲内のレベルを第２駆動信号（従って第１駆動信号）の第３補正レベルとして与えることで、上記暫定的変換テーブルデータから「制限補正テーブルデータ」を算出する。そして、ＣＰＵ２１は、この制限補正テーブルデータに基づき、前記ガンマ補正回路１３−１５の制御端に印加すべき変換テーブルデータを決定する。この場合、ＣＰＵ２１は、（ｉ）得られた上記制限補正テーブルデータをそのまま最終的な変換テーブルデータに設定しても良いし、あるいは、（ｉｉ）各色Ｒ，Ｇ，Ｂに関して変換テーブルデータのリミッタ値（過補正防止用データ）を設けておいて、このリミッタ値と上記制限補正テーブルデータとの比較処理から、更に上記制限補正テーブルデータに対して制限を課すことで更なる制限補正テーブルデータを求め、この新たな制限補正テーブルデータを最終的な変換テーブルデータに設定しても良い（詳しくは、後述する本変形例の修正例の記載を参照されたし）。
【００５０】
上述の記載から理解される通り、本変形例の適用に係るカラーディスプレイ装置の回路構成自体は実施の形態１の図３に例示するものと基本的に同一であり、ただＣＰＵ２１内部の機能が相違するのみである。従って、本変形例の記載に当っては、図３を援用する。
【００５１】
そこで、以下では、先ず、図６の近似曲線データから求められた変換曲線に対して制限を加えると言う着想に至った経緯（新たな問題点の認識）を記載した上で、本変形例の具体的構成をＣＰＵ２１の機能を示す図８のフローチャートに基づき記載する。尚、本変形例においても、好ましい態様として、３原色中の基準色をＢ（青色）に設定している。
【００５２】
＜着眼点＞
補正データ作成時における測定系の測定精度に起因して、測定用表示部３の明るさを正確に測定出来ない場合がある。ここで、「測定系」とは、図３のテストパターン発生回路１６−配線―切換回路１８−配線―測定用表示部駆動回路１９―配線―測定用表示部３−光センサ５−配線―入力端２１ＩＴから成る系統である。更に、外部からの電磁波の伝播による影響（ＥＭＩノイズ）の様な、何らかの外乱に起因して、同じく、測定用表示部３の明るさを正確に測定出来ない場合もある。その様な場合に対して、明らかな製品の異常を生じさせない様にするためには、ＣＰＵ２１は図６の近似曲線より算出した図７の補正量に対して適当な量の制限を加える必要性がある。即ち、上記の原因により生じるノイズを含む測定値を計測結果としてＣＰＵ２１が取得するときには、図６の近似曲線が示す入力信号に対する明るさは、ノイズがないときの本来の明るさと較べて、大きくなりがちとなる。そこで、ＣＰＵ２１は、計測結果から得られる近似曲線データを本来のデータに近づけるために、計測結果から得られる補正量に対して制限処理を施す必要性を有する。
【００５３】
＜具体例＞
図８は、本変形例におけるＣＰＵ２１における処理を示すフローチャートであり、図８中のステップＳ１−Ｓ３及びＳ５はそれぞれ図５中のステップＳ１−Ｓ３及びＳ５と同一である。従って、以下では、図８のステップＳ４１及び４２について記載する。
【００５４】
本変形例においては、ＣＰＵ２１は、ステップＳ４１で算出された暫定的変換テーブルデータ（算出方法は図５のステップＳ４で記載した方法と同一である）をそのままガンマ補正回路１３，１４，１５に送るのではなくて、当該暫定的変換テーブルデータに対して制限処理を施して、制限補正テーブルデータを生成する（ステップＳ４２）。ここでは、補正量制限の典型的な一例として、ＣＰＵ２１は、Ｇ（緑色）及びＲ（赤色）のそれぞれに関して、暫定的変換テーブルデータ（図７のＧに関する実線、図７のＲに関する２点鎖線）と、Ｂガンマ補正回路１５内に元来設定されている（補正前の）変換テーブル（即ち、図７のＢに関する破線の直線）との間の真ん中の位置を繋いで出来上がる曲線を与えるテーブルデータを算出して、その制限補正テーブルデータを、ガンマ補正回路１３，１４，１５に送信すべき最終的な変換テーブルデータに決定する。即ち、ＣＰＵ２１は、図７で示される暫定的変換テーブルデータより、（ａ）Ｒ（赤色）に関しては、（Ｋ１Ｒ＋Ｋ１）／２、（Ｋ２Ｒ＋Ｋ２）／２、及び（Ｋ３Ｒ＋Ｋ３）／２の演算処理を行い、（ｂ）Ｇ（緑色）に関しては、（Ｋ１Ｇ＋Ｋ１）／２、（Ｋ２Ｇ＋Ｋ２）／２、及び（Ｋ３Ｇ＋Ｋ３）／２の演算処理を行って、Ｒ（赤色）及びＧ（緑色）の制限補正テーブルデータを生成し、他方、（ｃ）Ｂ（青色）に関しては暫定的変換テーブルデータ（Ｋ１，Ｋ２，Ｋ３）そのものを制限補正テーブルデータに設定する。
【００５５】
尚、一般的には、既述した通り、ＣＰＵ２１は、（ａ）制限後のＲ（赤色）の出力信号ＫｉＲＡ（ｉは１、２、３）を、それぞれ、Ｋ１Ｒ＜Ｋ１ＲＡ＜Ｋ１、Ｋ２Ｒ＜Ｋ２ＲＡ＜Ｋ２、及びＫ３Ｒ＜Ｋ３ＲＡ＜Ｋ３の範囲内の任意値に設定すれば良く、（ｂ）制限後のＧ（緑色）の出力信号に関しても同様な設定をすれば良い。
【００５６】
その後、ＣＰＵ２１は、制限補正テーブルデータを変換テーブルデータに決定した上で、当該変換テーブルデータを第２制御信号ＶＣＴ２として各ガンマ補正回路１３，１４，１５に送信する（ステップＳ５）。その結果、ガンマ補正回路１３，１４，１５の各々は、受信した対応色の変換データに基づいて、経時変化により劣化したホワイトバランスを半分だけ改善する様に動作する。
【００５７】
これにより、本変形例によれば、測定系の精度あるいは電磁波ノイズ等の外乱に起因した誤動作を起こす事無く、加えるべき補正量を正確に決定することが可能となり、画像表示部１の表示特性の経時変化に拘わらず、良好なホワイトバランスを有する画像表示を実現することが出来る。
【００５８】
（変形例１の修正例）
更に、ＣＰＵ２１は、図８のステップＳ４２において算出した変換曲線のデータ、即ち、制限補正テーブルデータを、ＣＰＵ２１内の記憶領域内に予め記憶している制限変換曲線のデータ（即ち、リミッタ値）と逐一比較処理をすることによって、更なる補正量の制限（２重の制限）を行う様にしても良い。この場合、比較基準となる上記リミッタ値としては、▲１▼画像表示部１における第１画像が相対的に明るくなりすぎるのを阻止するための上限レベルであっても良いし、及び／又は、▲２▼逆に、画像表示部１における第１画像が相対的に暗くなりすぎるのを阻止するための下限レベルであっても良い。この様なデータ比較処理により、ＣＰＵ２１が、ある入力信号において、ステップＳ４２で算出された変換曲線（制限補正テーブルデータ）の出力信号が上記リミッタ値を与える記憶済み変換曲線の出力信号よりも過補正になることを検出した場合には、ＣＰＵ２１は、当該入力信号に対する出力信号の値を上記記憶済み変換曲線上の出力信号値に止めるように制限処理を実行する。
【００５９】
この様な上限／下限リミッタ値との比較処理を通じた更なる補正量の制限処理をＣＰＵ２１が行うことにより、ＣＰＵ２１は、経時変化補正後の第１画像が明るくなりすぎたり、あるいは、暗くなりすぎると言う過補正の発生を未然に防止することが出来る。
【００６０】
尚、本修正例における補正量制限方法は、変形例１への適用のみならず、既述した実施の形態１に対しても適用可能であり、更には、後述する全ての実施の形態及び変形例にも適用可能であり、如何なる適用例においても、過補正発生未然防止と言う同様の利点が得られる。
【００６１】
（変形例２）
本変形例は、変形例１とは別の着眼点及び異なる方法により、ＣＰＵ２１が図６の近似曲線より算出した暫定的な変換テーブルデータの補正量に対して制限を設ける点に、その特徴を有する。従って、本変形例においては、図３のＣＰＵ２１の機能・動作のみが実施の形態１及びその変形例１とは相違するだけであり、本変形例の記載においても基本的に図３を援用する。先ず、本変形例の特徴点を一般的に述べれば、次の通りである。
【００６２】
即ち、本変形例では、ＣＰＵ２１は、図３のカラーディスプレイ装置の工場出荷時からの経過時間ｔを計測するタイマを更に備えており、しかも、ＣＰＵ２１内部のガンマ補正制御部は、３原色中、基準色（ここでは例えば青色）を除く２色の内の第１色（ここでは例えば赤色）に関する上記経過時間ｔに対する第１補正係数α１及び他方の第２色（ここでは緑色）に関する上記経過時間ｔに対する第２補正係数α２をそれぞれ与える補正係数テーブルデータを、その記憶部内に更に有している。ここで、補正係数テーブルデータ内の補正係数α１及びα２は、測定系の経時変化特性に基づき定められており、しかも、第１及び第２補正係数α１及びα２は、共に０以上且つ１以下の範囲内の値である（０≦α１≦１、０≦α２≦１）。尚、ここで言う「測定系」とは、変形例１で既述したものである。
【００６３】
更に、ガンマ補正制御部は、（ａ）第１画像における３原色それぞれの明るさの比率を所定の比率とするために必要な（つまり、所望のホワイトバランスを得るのに必要な）、３原色中の基準色に関する第２駆動信号（従って、第１駆動信号）の第１レベルに対する第１及び第２色に関する第２駆動信号（従って、第１駆動信号）の第２及び第３レベルを与える暫定的変換テーブルデータを、近似曲線データに基づいて生成する。この点は、変形例１と共通するステップである。
【００６４】
更に、ガンマ補正制御部は、（ｂ）上記タイマの計測結果に応じて補正期間の開始時に対応する現経過時間を求めて、当該現経過時間における第１及び第２補正係数α１及びα２の値を上記補正係数テーブルデータより読み取る。
【００６５】
更に、ガンマ補正制御部は、（ｃ）第２駆動信号（従って、第１駆動信号）の第１レベルに対して、▲１▼基準色に関しては第２駆動信号（従って、第１駆動信号）の第１レベル自体を第２駆動信号の第１補正レベルとして与え、▲２▼他の２色の一方（第１色）に関しては、（１−第１補正係数α１）×（第２駆動信号の第１レベル）＋（第１補正係数α１）×（第２駆動信号の第２レベル）の関係式で与えられるレベルを第２駆動信号（従って、第１駆動信号）の第２補正レベルとして与え、且つ、▲３▼他の２色の他方（第２色）に関しては、（１−第２補正係数α２）×（第２駆動信号の第１レベル）＋（第２補正係数α２）×（第２駆動信号の第３レベル）の関係式で与えられるレベルを第２駆動信号（従って、第１駆動信号）の第３補正レベルとして与える制限補正テーブルデータを生成する。その上で、ガンマ補正制御部は、制限補正テーブルデータに基づき、最終の変換テーブルデータを決定する。この場合、ガンマ補正制御部は、（ｉ）制限補正テーブルデータそれ自体を変換テーブルデータに決定しても良く（後述する本変形例の具体例）、あるいは、（ｉｉ）変形例１の修正例を本変形例にも適用して、制限補正テーブルデータと上限及び／又は下限のリミッタ値との逐一の比較処理を通じて更なる補正量の制限を加えることで、過補正防止対策を施すこととしても良い。
【００６６】
そこで、以下では、先ず、図６の近似曲線データから求められた変換曲線に対して制限を加えると言う着想に至った経緯（新たな問題点の認識）を記載した上で、本変形例の具体的構成をＣＰＵ２１の機能を示す図９のフローチャートに基づき記載する。尚、本変形例においても、好ましい態様として、３原色中の基準色をＢ（青色）に設定している。
【００６７】
＜着眼点＞
補正データ作成時における、測定系の経時変化に起因して、計測により得られた測定値（Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂ）の精度が経時的に変化する場合がある。本変形例は、この様な場合においても、良好なホワイトバランスを実現するものである。
【００６８】
＜具体例＞
図９中、ステップＳ１−Ｓ３は図５に関するステップＳ１−Ｓ３に相当し、且つ、ステップＳ４１は図８におけるステップＳ４１に相当する。
【００６９】
ステップＳ４Ａにおいて、既述した通り、ＣＰＵ２１は、タイマを介して、プラズマディスプレイ装置の工場出荷時点からの使用経過時間を検知しており、しかも、測定系の経時変化特性を考慮して予め経験的ないしは実験的に得られたＲ（赤）に関する第１補正係数α１及びＧ（緑）に関する第２補正係数α２のデータを、その使用経過時間に対するテーブルデータとして、その記憶領域内に保有している。ここで、当該補正係数テーブルデータが対応可能な使用経過時間の上限とは、例えば本装置の平均的な使用耐久時間であったり、あるいは、本装置の保証期間である。いずれにせよ、ＣＰＵ２１は、その様な経過時間の上限までの各経過時間における第１及び第２補正係数α１、α２の全てを、テーブルデータとして保有しているのである。
【００７０】
ステップＳ４Ａにおいては、ＣＰＵ２１は、当該補正期間の開始時に当る経過時間のデータをタイマの計測値から取得した上で、現経過時間のデータに対する第１及び第２補正係数α１、α２の値を、上記の補正係数テーブルデータから抽出する。
【００７１】
ステップＳ４Ｂにおいては、ＣＰＵ２１は、第１色（Ｒ）及び第１色（Ｇ）のそれぞれに関して、各色に対応する図７中の変換曲線上の暫定的変換データに対して対応する補正係数を用いた次の補正制限処理を行って、制限された変換曲線を生成する。但し、ＣＰＵ２１は、基準色（Ｂ）に対する図７中の変換曲線上の暫定的変換データに対しては、その様な補正制限処理を一切行わず、基準色（Ｂ）に関する図７中の変換曲線上の暫定的変換データそのものを、最終的な変換テーブルデータに設定する。即ち、ＣＰＵ２１は、（ａ）Ｒ（赤）に関しては、画像の補正量に当該経過時間における第１補正係数α１を掛けることで補正量を制限する、即ち、Ｋｉ−α１×（Ｋｉ−ＫｉＲ）＝（１−α１）×Ｋｉ＋α１×ＫｉＲ（ｉ＝１，２，３）の式で与えられる補正データを、入力信号Ｋｉに対する出力信号とする、制限補正テーブルデータを生成すると共に、（ｂ）Ｇ（緑）に関しても同様に、（１−α２）×Ｋｉ＋α２×ＫｉＧ（ｉ＝１，２，３）の式で与えられる補正データを、入力信号Ｋｉに対する出力信号とする、制限補正テーブルデータを生成する。例えば、Ｒ（赤）の制限変換曲線は、第１補正係数α１が１であれば図７のＲ（赤）の暫定的変換曲線と同じになる。これに対して、第１補正係数α１が０であれば、Ｒ（赤）の制限変換曲線は図７のＢ（青）の直線と等しくなり、この場合には補正が働かない。又、第１補正係数α１が０．５であれば、Ｒ（赤）の制限変換曲線は、図７のＲ（赤）の暫定的変換曲線とＢ（青）の直線との真ん中に存在する。
【００７２】
次のステップＳ５において、ＣＰＵ２１は、制限補正テーブルデータを変換テーブルデータとして、即ち、第２制御信号ＶＣＴ２として、各ガンマ補正回路１３−１５に送信する。それ以後の各ガンマ補正回路１３−１５の動作は、実施の形態１で記載した通りである。即ち、各ガンマ変換回路１３，１４，１５は、対応する変換テーブルデータを受け取り、以後それに従って、入力信号から出力信号への変換を行い、ホワイトバランスが良好な画像表示を第１画像として画像表示部１に表示する。
【００７３】
以上の様に、本変形例においては、読み取った現使用経過時間に対応する補正係数を図７の変換曲線に操作することで補正量を適切に制限して、実際に補正を行う変換曲線（変換テーブルデータ）を生成している。このため、本変形例によれば、ＣＰＵ２１は、測定系の経時変化によって測定値精度が経時的に変動する場合においても、実施の形態１と同様に、良好なホワイトバランスを有する第１画像を画像表示部１上に実現することが出来る。
【００７４】
（変形例３）
本変形例は、実施の形態１の改良技術に係わり、特に変形例２の修正に関するものである。従って、変形例２の場合と比較して、ＣＰＵ２１の機能のみが相違する点に特徴があるため、本変形例においても図３を基本的に援用する。
【００７５】
即ち、本変形例の特徴点として、ＣＰＵ２１は、変形例２の様に全ての使用経過時間に対する第１及び第２補正係数のテーブルデータを記憶しているのではなくて、所定の時間が経過する毎に定期的に行う複数の補正期間の各々に対応する経過時間における補正係数データのみを離散的にテーブルデータとして保有するのみである。この構成によって、本変形例においては、変形例２の場合と比較してＣＰＵ２１内に保有乃至は記憶しておく補正係数のデータ量を格段に低減可能としており、この利点は回路構成全体をより簡単化することに寄与し得る。
【００７６】
尚、ＣＰＵ２１は必ずしも定期的な時間経過毎に補正を行う必要性はなく、使用経過時間の経過中の、ある補正期間（第１補正期間）とその次の補正期間（第２補正期間）との間の経過時間を任意の時間に設定しても良いことは勿論であり、この様な一般的な場合においても同様の効果が得られる。
【００７７】
以下、ＣＰＵ２１内の処理を示す図１０のフローチャートに基づいて、本変形例を詳述する。尚、図１０中の各ステップの内で本変形例に特有なものは、ステップＳ４ＡＡ及びＳ６であり、その他のステップは既述したものである。
【００７８】
ＣＰＵ２１は、その内部の記憶領域内に、最初の補正期間に対応する経過時間（ｔ１）、その次の補正期間に対応する経過時間（ｔ２）、更にその次の補正期間に対応する経過時間（ｔ３）、…、第ｎ番目の補正期間に対応する経過時間（ｔｎ）、…のそれぞれに対する第１及び第２補正係数α１及びα２のデータから成る補正係数テーブルデータ（このテーブルデータは、変形例２の場合（ほぼ連続的なデータ群）とは異なり、離散的なデータから成るデータ群である）を、予め格納している。ここで言う第１及び第２補正係数α１及びα２は、変形例２で既述したものであり、何れも０以上及び１以内の範囲内の値を有する。
【００７９】
先ず、最初の補正期間の到来によって、ＣＰＵ２１は、光センサ５の出力信号Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂより図６に示す近似曲線データを生成した上で、所定のホワイトバランスを得る様に、図７に示す暫定的な変換曲線データを生成する（ステップＳ１Ａ−Ｓ４１）。
【００８０】
そして、ＣＰＵ２１は、上記の補正係数テーブルデータから、当該補正期間の開始時刻に当る経過時間（ｔ１）に対応する第１及び第２補正係数α１及びα２を読み出した上で（ステップＳ４ＡＡ）、当該第１及び第２補正係数α１及びα２に基づき図７に示す暫定的な変換曲線データに対して補正量制限処理を行う。その処理は、具体的には、変形例２の図９におけるステップＳ４Ｂで行われる補正量制限処理と同一である。その後、ＣＰＵ２１は、ステップＳ４Ｂで算出された制限補正テーブルデータに基づき、最終的にガンマ補正回路に指令すべき変換テーブルデータを決定する。その際、ＣＰＵ２１は、変形例１の修正例の技術（リミッタ値による更なる補正制限処理）を適用して変換テーブルデータを決定しても良いが、ここでは、記載の便宜上、ＣＰＵ２１は、制限補正テーブルデータ自体を変換テーブルデータに決定するものとする。
【００８１】
その後、ＣＰＵ２１は、その内部に有するタイマが示す現経過時間と、同じくその内部に有する、次の補正期間に対応する経過時間（ｔ２）とが等しくなるか否かを監視し続け（ステップＳ６）、現経過時間が上記経過時間（ｔ２）に到達したときに、ＣＰＵ２１は、再び光センサ５より測定データを取得した上で、図６の近似曲線データの作成、及び、それに引き続く図７の暫定的変換テーブルデータを生成し、今度は上記経過時間（ｔ２）に対応する第１及び第２補正係数α１及びα２を読み出した上で、同様の補正量制限処理を実行する。
【００８２】
以下、ＣＰＵ２１は、図１０に示す様に、引き続き補正期間が到来する毎に、同様の補正量制限処理及び変換テーブルデータの決定・出力処理を行う。
【００８３】
以上の通り、本変形例によれば、補正量の設定をある定期的な時間毎に行うため、常時回路を動作させる必要がないため回路動作を簡単に出来ると共に、ＣＰＵ２１がその内部で持つ補正係数テーブルも簡単化することが出来、その結果、測定系の経時変化を考慮した上での良好なホワイトバランスを有する第１画像を画像表示部１上に簡易に表示することが可能となる。
【００８４】
（変形例４）
本変形例は変形例３の改良技術に関しており、その特徴点は、変形例３における、ある補正期間（第１補正期間）と、その次の補正期間（第２補正期間）との間の経過時間中に、ＣＰＵ２１は、第１及び第２補正係数の値をそれぞれ第１補正期間に対応する経過時間における対応抽出値に向けて徐々に増大させながら、補正量の制限処理の実行及びガンマ補正回路への変換テーブルデータの送信を継続させて行く点にある。従って、ここでも、図３の回路図を援用しつつ、その具体例を以下に記載する。尚、第１及び第２補正係数の値を徐々に増大させることは必須ではなく、少なくとも抽出した第１及び第２補正係数α１、α２よりも小さな第１及び第２先行補正係数α１Ａ、α２Ａを用いた第１及び第２先行制限処理（第１及び第２補正係数α１、α２を用いた第１及び第２制限処理よりも先行する処理）を、少なくとも一回行うだけでも良い。
【００８５】
図１１は、本変形例における主としてＣＰＵ２１における動作・機能を示したフローチャートであり、変形例３と相違する特徴点はステップＳ４ＡＡ１〜Ｓ４ＡＡ３に存在する。尚、図１１中において、既に表れたステップ番号と同一の番号を有するステップは、それぞれ対応する既述のステップと同様の内容を有するので、本変形例においては、それらの記載を割愛している。
【００８６】
ＣＰＵ２１は、ある補正期間（第１補正期間）と次の補正期間（第２補正期間）との間において、徐々に補正係数を本来の値に向けて増大させて変換データテーブルを生成・出力して行き、最終的には、補正係数テーブルデータから読み出した本来の補正係数値を用いて、あるべき変換データテーブルを生成・出力する。
【００８７】
ステップＳ４ＡＡ１において、ＣＰＵ２１は、当該補正期間（第１補正期間）の開始時間（例えばｔＡとする）に対応する、補正係数テーブルデータより読み出した第１及び第２補正係数α１、α２よりも、十分に小さな任意値α１０、α２０を、それぞれ第１及び第２補正係数（第１及び第２先行補正係数とも称す）α１Ａ、α２Ａに設定する。
【００８８】
その上で、ＣＰＵ２１は、第１及び第２補正係数α１Ａ（＝α１０）、α２Ａ（＝α２０）を用いて、変形例３において既述したステップＳ４Ｂを行って制限補正テーブルデータ（先行制限補正テーブルデータとも称す）を算出し、当該制限補正テーブルデータを変換テーブルデータ（第２制御信号ＶＣＴ２）として各色のガンマ補正回路１３−１５に送信する。
【００８９】
ステップＳ４ＡＡ２において、ＣＰＵ２１は、第１及び第２補正係数α１Ａ（＝α１０）及びα２Ａ（＝α２０）にそれぞれ任意の増大値Δα１及びΔα２（増大値Δα１及びΔα２は毎回一定値でも良いし、又は、その度毎に異なる値であっても良い）を加算することで、第１及び第２補正係数α１Ａ及びα２Ａを徐々にながら増大させる。そして、ＣＰＵ２１は、増大後の第１及び第２補正係数α１Ａ＋Δα１、α２Ａ＋Δα２をそれぞれ新たな第１及び第２補正係数α１Ａ及びα２Ａに設定し、これらの新たな第１及び第２補正係数α１Ａ及びα２Ａを用いて、再度、変形例３において既述したステップＳ４Ｂを行って制限補正テーブルデータを算出し、当該制限補正テーブルデータを変換テーブルデータ（第２制御信号ＶＣＴ２）として各色のガンマ補正回路１３−１５に送信する。
【００９０】
そして、ＣＰＵ２１は、この様な処理を繰り返して第１及び第２補正係数を徐々に増大させて変換テーブルデータを徐々に増大化させる方向で更新して行き、ステップＳ４ＡＡ３において、増大後の第１及び第２補正係数α１Ａ＋Δα１、α２Ａ＋Δα２が経過時間ｔＡに対応する補正係数テーブルデータより読み出した第１及び第２補正係数α１、α２の値に最終的に到達したのを検知した時点で、それ以後は第１及び第２補正係数の増大化処理を止めると共に、最終的な第１及び第２補正係数α１、α２の本来値を用いて、変形例３において既述したステップＳ４Ｂを行って本来あるべき制限補正テーブルデータを算出し、当該制限補正テーブルデータを時刻ｔＡにおける本来の変換テーブルデータ（第２制御信号ＶＣＴ２）として各色のガンマ補正回路１３−１５に送信する。
【００９１】
以上の処理を具体的な数値を用いて、より具体的に以下に例示記載する。一例として、Ｒ（赤色）の第１補正係数α１（＝１）に焦点を当てて記載する。即ち、ＣＰＵ２１は、ある補正期間の最初の段階においては、図７の補正データに補正係数０．２を乗じて得られる変換データを各色のガンマ補正回路１３，１４，１５に送信する。その後、予め定められたある時間が経過したのをＣＰＵ２１が検知した上で、ＣＰＵ２１は、補正係数を０．２から０．５へと少しばかり増大させて、補正データに増大後の新補正係数０．５を乗じて、得られた変換データを再び各色のガンマ補正回路１３，１４，１５に送信する。その後、更にある時間が経過したのを検知したＣＰＵ２１は、補正係数の値を０．５から最終的な値である１に増大させた上で、補正データに本来の補正係数１を乗じ、その結果得られた変換データを再度各ガンマ補正回路１３，１４，１５に送信する。それ以後は、次の補正期間が到来するまでは、ＣＰＵ２１は変換テーブルデータを更新することはない。
【００９２】
この様に、本変形例においては、徐々に、ガンマ補正回路１３，１４，１５に送るべき変換データを増大させていく。
【００９３】
以上の構成により、ガンマ補正回路の補正により急激にホワイトバランスが変化する自体を未然に防止することが可能となり、良好なホワイトバランスを実現することが出来る。換言すれば、求めた補正量の設定を一度に行うのではなく、ある定期的な時間をかけて徐々に補正量を大きくして行き、変換データを最終的に求めた補正量に設定するため、ゆっくりと補正が働き、違和感のない良好なホワイトバランスを簡易に得ることが出来る。
【００９４】
（実施の形態２）
本実施の形態は、実施の形態１を改良するものであり、ホワイトバランスのみならず、輝度をも適正化することを目的としている。
【００９５】
即ち、プラズマディスプレイ装置が工場出荷時以後ある時間使用されているときには、経年変化により、工場出荷時のそれよりも、Ｒ（赤）、Ｇ（緑）、及びＢ（青）各色の明るさが暗くなっている。これによって、工場出荷後のプラズマディスプレイ装置における輝度とホワイトバランスとは、共に工場出荷時の輝度とホワイトバランスとよりも悪くなっている。
【００９６】
そこで、本実施の形態では、ＣＰＵ２１が工場出荷時に調整済みの各色の明るさデータを予め記憶しておき、工場出荷後のある補正期間において、そのときに第３画像より測定・検出されたＲ（赤）、Ｇ（緑）、及びＢ（青）各色の明るさデータがそれぞれ工場出荷時に調整済みの各色の明るさデータに等しくなる様に、ガンマ補正回路に印加すべき変換曲線データ（ガンマ補正回路の入力信号と出力信号の変換テーブル）を、ＣＰＵ２１において生成する。この様に、本実施の形態と実施の形態１との相違点は専らＣＰＵ２１の動作・機能にあるので、本実施の形態においても、図３の回路図を援用する。
【００９７】
本実施の形態の特徴を一般化して述べれば、次の通りである。即ち、ＣＰＵ２１のガンマ補正制御部は、第１画像のホワイトバランス及び輝度の調整が完了している工場出荷時における、第２駆動信号Ｖ１９Ｒ，Ｖ１９Ｇ，Ｖ１９Ｂ（従って第１駆動信号Ｖ２０Ｒ，Ｖ２０Ｇ，Ｖ２０Ｂ）に対する３原色それぞれの明るさを与える「工場出荷時テーブルデータ」（後述する図１３中の太実線に相当）を予め記憶部内に保有している。その上で、ＣＰＵ２１のガンマ補正制御部は、工場出荷時テーブルデータ、レベルデータ（後述する図１３の入力信号Ｋ１，Ｋ２，Ｋ３）及び被検出３原色明るさ信号Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂに基づいて、補正期間における第３画像（従って第１画像）のホワイトバランス及び輝度がそれぞれ工場出荷時における第３画像（従って第１画像）のホワイトバランス及び輝度に等しくなる様に、変換テーブルデータを生成する。以下、ＣＰＵ２１のガンマ補正制御部としての動作を、図１２のフローチャートにおけるステップＳ３Ａ，Ｓ４Ａ，Ｓ５に則して、詳述する。
【００９８】
図１２のステップＳ３Ａにおいて、ＣＰＵ２１は、▲１▼各テストパターンＫ１，Ｋ２，Ｋ３における光センサ５の検出レベルＶ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂと、▲２▼レベルデータ（後述する図１３の入力信号Ｋ１，Ｋ２，Ｋ３）とに基づいて、図６と同様な図１３に示す、Ｒ（赤）、Ｇ（緑）、及びＢ（青）各色の近似曲線を与えるデータを生成する。図１３より理解される様に、太実線で表示されている工場出荷時の明るさ（光量）と比較すると、測定用表示部３の第３画像、従って画像表示部１における第１画像のＢ（青）が３原色の内で最も暗くなっており、そのため、経時劣化を受けたＢ（青）の明るさを工場出荷時の明るさにまで回復させるには、３原色の内で最も大きな電力を投入・消費させる必要性がある（つまり、補正後の入力信号のレベルはより大となる）。尚、本実施の形態においても同様に、記載の便宜から、Ｒ（赤）、Ｇ（緑）、及びＢ（青）各色の明るさが互いに等しいレベルにあるときに（明るさの比率が１：１：１）、ホワイトバランスが良好な状態にあるものとしている。
【００９９】
次に、図１２のステップＳ４Ａにおいて、ＣＰＵ２１は、▲１▼図１３における、Ｒ（赤）、Ｇ（緑）、及びＢ（青）各色の近似曲線データと、▲２▼図１３において太実線で表示される工場出荷時テーブルデータとの比較処理により、工場出荷時の明るさを実現し得る各色の入力信号をそれぞれ求めて、図１４に示す変換曲線テーブルを作成する。尚、図１４には、参考として、図１３の太実線の工場出荷時テーブルデータ自体に対する変換直線を太実線として表示している。そして、ＣＰＵ２１は、作成した各色の変換テーブルデータを第２制御信号ＶＣＴ２として各色のガンマ補正回路１３，１４，１５に送信する（ステップＳ５）。
【０１００】
各色のガンマ変換回路１３，１４，１５は、変換テーブルデータＶＣＴ２を受け取り、以後その変換データに従って、入力信号から出力信号への変換を行う。その結果、工場出荷後の使用時点におけるＲ（赤）、Ｇ（緑）、及びＢ（青）各色の輝度と、ホワイトバランスとが、それぞれ、工場出荷時における各色の輝度と、ホワイトバランスとに合致した良好な画像表示が、画像表示部１において得られる。
【０１０１】
（変形例５）
本変形例は、実施の形態２に変形例１の改良技術を適用したものであり、従って、変形例１の効果を実施の形態２の技術にも付加することを、その目的としている。本変形例においても、既述の図３を援用することとして、先ず、本変形例の特徴点を一般化して記載すれば、次の通りである。
【０１０２】
ＣＰＵ２１のガンマ補正制御部は、（ａ）レベルデータ（図１３及び図１４の入力信号Ｋ１，Ｋ２，Ｋ３）及び被検出３原色明るさ信号Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂに基づいて、３原色それぞれに関する、第２駆動信号Ｖ１９Ｒ，Ｖ１９Ｇ，Ｖ１９Ｂと第３画像における明るさとの関係を示す図１３の近似曲線データを生成した上で、（ｂ）補正期間における第１画像のホワイトバランス及び輝度をそれぞれ工場出荷時における第１画像のホワイトバランス及び輝度に等しくするために必要な、３原色の第１色（例えばＲ）、第２色（例えばＧ）及び第３色（例えばＢ）に関する第２駆動信号、従って第１駆動信号Ｖ２０Ｒ，Ｖ２０Ｇ，Ｖ２０Ｂの第１、第２及び第３レベル（例えば、図１３の例では、簡単化のために第１−第３レベルは互いに等しい値であると設定されており、それらは共に入力信号Ｋ３である）に対する第１、第２及び第３補正レベル（例えば、図１３の例では、出力信号Ｋ３Ｒ，Ｋ３Ｇ，Ｋ３Ｂ）を与える暫定的変換テーブルデータを、工場出荷時テーブルデータ及び近似曲線データに基づいて生成する。
【０１０３】
（ｃ）更に、ＣＰＵ２１のガンマ補正制御部は、▲１▼第１色（Ｒ）に関しては、工場出荷時における第１駆動信号Ｖ２０Ｒの第１レベル（例えば図１４のＫ３）と第１補正レベル（例えば図１４のＫ３Ｒ）とで規定され且つ工場出荷時における第１レベル及び第１補正レベルを除く範囲内のレベルを、工場出荷時における第１レベル（例えば図１４のＫ３）に対する、第１駆動信号の第１制限補正レベルとして与える。又、ガンマ補正制御部は、▲２▼第２色（Ｇ）に関しては、工場出荷時における第１駆動信号の第２レベル（例えば図１４のＫ３）と第２補正レベル（例えば図１４のＫ３Ｇ）とで規定され且つ工場出荷時における第２レベル及び第２補正レベルを除く範囲内のレベルを、工場出荷時における第２レベル（例えば図１４のＫ３）に対する、第１駆動信号の第２制限補正レベルとして与える。更に、ガンマ補正制御部は、▲３▼第３色（Ｂ）に関しては、工場出荷時における第１駆動信号の第３レベル（例えば図１４のＫ３）と第３補正レベル（例えば図１４のＫ３Ｂ）とで規定され且つ工場出荷時における第３レベル及び第３補正レベルを除く範囲内のレベルを、工場出荷時における第３レベル（例えば図１４のＫ３）に対する、第１駆動信号の第３制限補正レベルとして与える。そして、ガンマ補正制御部は、少なくともこれらの第１−第３制限補正レベルに基づいて、制限補正テーブルデータを生成し、その上で、制限補正テーブルデータに基づき、変換テーブルデータを決定する（その際、変形例１の修正例を適用しても良い）。
【０１０４】
以下、ＣＰＵ２１の動作・機能を示す図１５のフローチャートに従って、本変形例をより具体的に記載する。但し、図１５が既述の図８と相違する点を中心に記載する。
【０１０５】
図１５のステップＳ４１Ａにおいて、ＣＰＵ２１は、図１３の太実線で表示される工場出荷時テーブルデータと図１３の各色の近似曲線データとの比較処理により、図１４に示す各色の変換直線データを暫定的変換テーブルデータとして生成する。
【０１０６】
その上で、ステップＳ４２Ａにおいて、ＣＰＵ２１は、図８のステップＳ４２と同様の処理を、各色Ｒ（赤）、Ｇ（緑）及びＢ（青）に対して施し、制限補正テーブルデータを生成する。その結果、例えばＢ（青）に対する補正制限においては、Ｂ（青）色の制限補正データが与える変換直線は、図１４の破線で表示されている直線上の位置データと、その位置に対応する太い実線で表示されている直線上の位置データとの中間値データで以って表示される直線となる。他の２色の補正制限においても、同様である。
【０１０７】
以上より、本変形例によれば、外乱等の誤動作では悪化しない良好な輝度及びホワイトバランスを有する第１画像を、画像表示部１上に表示することが出来る。
【０１０８】
（変形例６）
本変形例は、実施の形態２に変形例２の改良技術を適用したものであり、従って、変形例２の効果を実施の形態２の技術にも付加することを、その目的としている。本変形例においても、既述の図３を援用することとして、先ず、本変形例の特徴点、即ち、第１−第３色の第１−第３補正係数に基づいて変換曲線データを制限すると言う着想を、実際に行う処理に基づいて一般的に記載すれば、次の通りである。
【０１０９】
即ち、ＣＰＵ２１のガンマ補正制御部は、「経過時間に対する、３原色の第１、第２及び第３色に関する第１、第２及び第３補正係数を与える補正係数テーブルデータ」を記憶する記憶部を更に有しており、これらの補正係数テーブルデータは、変形例２と同様に、測定系の軽時変化特性に基づき定められており、しかも、記第１、第２及び第３補正係数は何れも０以上且つ１以下の範囲内の値である。
【０１１０】
そして、ＣＰＵ２１のガンマ補正制御部は、（ａ）３原色の第１、第２及び第３色に対する第１、第２及び第３補正レベルを与える暫定的変換テーブルデータを、工場出荷時テーブルデータ及び近似曲線データに基づいて生成した上で、（ｂ）タイマの計測結果に応じて補正期間の開始時に対応する現経過時間を求め、当該現経過時間における第１、第２及び第３補正係数の値を補正係数テーブルデータより読み取った上で、これらの補正係数を用いて第１、第２及び第３補正レベルに対して以下の補正制限処理（ｃ）を実行する。
【０１１１】
即ち、ＣＰＵ２１のガンマ補正制御部は、▲１▼第１色（例えばＲ）に関しては、（１−第１補正係数）×（工場出荷時における第１駆動信号の第１レベル）＋（第１補正係数）×（第１駆動信号の第１補正レベル）の関係式で与えられるレベルを、工場出荷時における第１駆動信号の第１レベルに対する、第１駆動信号の第１制限補正レベルとして与える。又、ガンマ補正制御部は、▲２▼第２色（例えばＧ）に関しては、（１−第２補正係数）×（工場出荷時における第１駆動信号の第２レベル）＋（第２補正係数）×（第１駆動信号の第２補正レベル）の関係式で与えられるレベルを、工場出荷時における第１駆動信号の第２レベルに対する、第１駆動信号の第２制限補正レベルとして与えると共に、▲３▼第３色（例えばＢ）に関しては、（１−第３補正係数）×（工場出荷時における第１駆動信号の第３レベル）＋（第３補正係数）×（第１駆動信号の第３補正レベル）の関係式で与えられるレベルを、工場出荷時における第１駆動信号の第３レベルに対する、第１駆動信号の第３制限補正レベルとして与える。そして、ＣＰＵ２１のガンマ補正制御部は、これらの制限補正レベルを用いて、制限された変換曲線を与える制限補正テーブルデータを生成し、この制限補正テーブルデータに基づき、変換テーブルデータを決定する。
【０１１２】
ここで、図１６は、本変形例におけるＣＰＵ２１（ガンマ補正制御部）の上述の動作を図１３及び図１４のケースに則して示すフローチャートであり、図９に対応するものである。
【０１１３】
以上の通り、本変形例においては、読み取った現使用経過時間に対応する第１−第３補正係数α１、α２、α３を図１４の暫定的な変換曲線に操作することで補正量を適切に制限して、実際に補正を行うための変換曲線（変換テーブルデータ）を生成している。このため、本変形例によれば、ＣＰＵ２１は、測定系の経時変化によって測定値精度が経時的に変動する場合においても、実施の形態２と同様に、良好な輝度及び良好なホワイトバランスを有する第１画像を画像表示部１上に実現することが出来る。
【０１１４】
（変形例７）
本変形例は、実施の形態２に変形例３の改良技術（定期的に補正を実行する点）を適用したものであり、従って、変形例３の効果を実施の形態２の技術にも付加することを、その目的としている。本変形例においても、既述の図３を援用する。
【０１１５】
図１７は、図１０に対応するフローチャートであり、本変形例におけるＣＰＵ２１（ガンマ補正制御部）の動作を示している。図１７に示す動作においては、補正係数が３原色の各色毎に存在することに対応する処理が図１０に示す動作に対して新たに付け加わるだけであり、基本的な考え方に変わりはないので、図１７の動作の記載を割愛する。
【０１１６】
本変形例によれば、補正量の設定をある定期的な時間毎に行うため、常時回路を動作させる必要がないため回路動作を簡単に出来ると共に、ＣＰＵ２１がその内部で持つ補正係数テーブルも簡単化することが出来、その結果、測定系の経時変化を考慮した上での、良好な輝度及び良好なホワイトバランスを共に有する第１画像を画像表示部１上に簡易に表示することが可能となる。
【０１１７】
（変形例８）
本変形例は、実施の形態２に変形例４の改良技術（定期的補正であって、ある補正期間と次の補正期間との間において、徐々に補正係数を本来の係数値に向けて増大させる点）を適用したものであり、従って、変形例４の効果を実施の形態２の技術においても実現可能とすることを、その目的としている。本変形例においても、既述の図３を援用する。
【０１１８】
ここで、図１８は、図１１に対応するフローチャートであり、本変形例におけるＣＰＵ２１（ガンマ補正制御部）の動作を示している。図１８に示す動作においては、補正係数が３原色の各色毎に存在することに対応する処理が図１１に示す動作に対して新たに付け加わるだけであり、基本的な考え方に変わりはないので、図１８の動作の記載を割愛する。
【０１１９】
本変形例によれば、ガンマ補正回路の補正により急激に輝度及びホワイトバランスが変化する自体を未然に防止することが可能となり、良好な輝度及び良好なホワイトバランスを実現することが出来る。換言すれば、求めた補正量の設定を一度に行うのではなく、ある定期的な時間をかけて徐々に補正量を大きくして行き、変換データを最終的に求めた補正量に設定するため、ゆっくりと補正が働き、違和感のない良好な輝度及び良好なホワイトバランスを簡易に得ることが出来る。
【０１２０】
（その他の変形例）
１）実施の形態１、２や各変形例１−８において既述した光センサ５による明るさ測定に関して、１度の測定で測定結果Ｖ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂを設定するのではなくて、光センサ５が何度かの明るさ測定をして、例えばそれらの測定値の平均値を採ることにより、測定値データＶ５Ｒ，Ｖ５Ｇ，Ｖ５Ｂを導出することとしても良く、この場合には、より精度の良い明るさ測定が可能となる。
２）実施の形態１、２や各変形例１−８はプラズマディスプレイ装置について記載しているが、同様に、自発光素子を用いたＣＲＴディスプレイ、無機・有機ＥＬディスプレイ、その他の表示カラーディスプレイ装置についても、本発明の主題を適用することが可能であり、何れの場合においても、良好なホワイトバランス、あるいは、良好な輝度及びホワイトバランスを、実現することが出来る。
【０１２１】
（付記）
以上、本発明の実施の形態を詳細に開示し記述したが、以上の記述は本発明の適用可能な局面を例示したものであって、本発明はこれに限定されるものではない。即ち、記述した局面に対する様々な修正や変形例を、この発明の範囲から逸脱することの無い範囲内で考えることが可能である。
【０１２２】
【発明の効果】
この発明に係るカラーディスプレイ装置は、以下に示す効果を奏する。即ち、通常動作期間においては、測定用表示部において、画像表示部で表示すべき本来の第１画像の平均的明るさを有する第２画像を表示しているので、通常動作期間における画像表示部の表示特性の経時変化を測定用表示部の表示特性の経時変化にほぼ等しく反映させることが出来、その様な条件下において、次の補正期間において測定した測定用表示部の明るさの検出データは、ほぼ同一期間分の経時変化を受けた画像表示部における第１画像の明るさであるとみなすことが出来る。特に補正期間における測定期間が短い程、この同一性擬制の観点は顕著となる。そのため、本装置においては、実際の表示画面の劣化状況を正確に反映させつつ、測定した明るさデータに応じて、表示すべき本来の画像のホワイトバランスを精度良く補正することが可能となり、良好なホワイトバランスを簡易に得ることが出来る。
【図面の簡単な説明】
【図１】この発明の実施の形態１に係るプラズマディスプレイ装置のプラズマディスプレイパネルを示す平面図である。
【図２】この発明の実施の形態１に係るプラズマディスプレイ装置を示す図である。
【図３】この発明の実施の形態１に係るプラズマディスプレイ装置を示すブロック図である。
【図４】この発明の実施の形態１の平均の明るさ回路のＧ出力信号を示す図である。
【図５】この発明の実施の形態１におけるＣＰＵの動作を示すフローチャートである。
【図６】この発明の実施の形態１における測定用表示部の入力信号と明るさとの特性を与える近似曲線を示す図である。
【図７】この発明の実施の形態１における入出力特性（変換曲線）を示す図である。
【図８】この発明の変形例１におけるＣＰＵの動作を示すフローチャートである。
【図９】この発明の変形例２におけるＣＰＵの動作を示すフローチャートである。
【図１０】この発明の変形例３におけるＣＰＵの動作を示すフローチャートである。
【図１１】この発明の変形例４におけるＣＰＵの動作を示すフローチャートである。
【図１２】この発明の実施の形態２におけるＣＰＵの動作を示すフローチャートである。
【図１３】この発明の実施の形態２における測定用表示部の入力信号と明るさとの特性を与える近似曲線を示す図である。
【図１４】この発明の実施の形態２における変換曲線を示す図である。
【図１５】この発明の変形例５におけるＣＰＵの動作を示すフローチャートである。
【図１６】この発明の変形例６におけるＣＰＵの動作を示すフローチャートである。
【図１７】この発明の変形例７におけるＣＰＵの動作を示すフローチャートである。
【図１８】この発明の変形例８におけるＣＰＵの動作を示すフローチャートである。
【符号の説明】
１画像表示部、２表示パネル周辺部、３測定用表示部、４表示パネル、５光センサ、６遮光カバー、１０Ｒ信号入力端子、１１Ｇ信号入力端子、１２Ｂ信号入力端子、１３Ｒガンマ補正回路、１４Ｇガンマ補正回路、１５Ｂガンマ補正回路、１６テストパターン発生回路、１７平均の明るさ生成回路、１８切換回路、１９測定用表示部駆動回路、２０画像表示部駆動回路、２１ＣＰＵ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color display device (for example, a plasma display device, a CRT display device, an inorganic or organic EL display device) using a self-luminous element, and correction of luminance and white balance for obtaining a particularly good image. Belongs to technology.
[0002]
[Prior art]
In color display devices, the white balance varies due to variations in the light emission characteristics of the R (red), G (green), and B (blue) pixel elements in the display panel. It has been broken.
[0003]
However, after the white balance adjustment is completed, if the light emitting part of the display panel itself (the phosphor itself in the CRT panel or plasma display panel, or the EL element in the EL display panel) deteriorates due to a change with time, the white balance shift and the luminance decrease. There is a problem that occurs.
[0004]
In a conventional plasma display device, as a method for solving this problem, a method of correcting a white balance by providing a photosensor in a plasma display panel and measuring the light emission of the preliminary discharge electrode by the photosensor is proposed. (For example, see Patent Document 1). However, in this method, the light emitted from the preliminary discharge electrode is used, and the information obtained from the optical sensor output may not reflect the deterioration state of the display screen, so that there is a problem that the correction is not sufficient. Can occur.
[0005]
Moreover, the display apparatus in the conventional projection television measures the overscan part (for example, refer patent document 2). However, in this method, there is a case where information obtained from the display of the overscan portion does not reflect the deterioration state of the display screen, and therefore the same problem that correction is not sufficient may occur.
[0006]
For this reason, none of the prior arts proposed in both Patent Documents 1 and 2 can be an effective solution to this problem.
[0007]
[Patent Document 1]
JP-A-8-9415 (page 2-4, FIG. 2)
[Patent Document 2]
JP-A-9-37281 (page 2-3, FIG. 1)
[0008]
[Problems to be solved by the invention]
As described above, in the conventional color display device using a self-luminous element, there is a problem that when the phosphor itself in the display panel deteriorates due to aging, a white balance shift and a luminance decrease occur. ing. In addition, the above-described conventional technology has a problem in that when measuring the decrease in luminance of the display device, the state of deterioration of the display screen over time cannot be measured correctly.
[0009]
The present invention has been made to solve such a matter of concern, and its main purpose is to obtain an image with good white balance in consideration of deterioration of the display screen due to change with time. It is to provide a correction technique. Furthermore, a secondary object of the present invention is to provide a correction technique capable of obtaining an image with good luminance and white balance in consideration of deterioration of the display screen due to change with time.
[0010]
[Means for Solving the Problems]
The subject of the present invention is a gamma correction means for performing gamma correction on an input three primary color signal and outputting a corrected three primary color signal after correction, and the three primary colors based on the corrected three primary color signals of the gamma correction means. An image display unit driving means for generating a first drive signal and outputting the first drive signal; an image display unit for displaying a first image given by the input three primary color signals based on the first drive signal; The second light emission characteristic is the same as the first light emission characteristic of the image display unit, and the second time change characteristic is the same as the first time change characteristic of the image display unit, and the second image is displayed in the normal operation period. On the other hand, during the correction period, the measurement display unit for displaying the third image and the three primary color signals to be corrected of the gamma correction means perform an averaging process for one screen to obtain the input three primary colors. Trust Average brightness calculation means for generating averaged three primary color signals giving average brightness and outputting the averaged three primary color signals, and three primary color test patterns giving at least one type of measurement screen A test pattern generating means for holding the signal and outputting the three primary color test pattern signals, and the averaged three primary color signals output from the average brightness calculating means in accordance with the level of the first control signal. A switching means for switching between a first connection to be output or a second connection for outputting the three primary color test pattern signals output from the test pattern generation means; and a third connection relating to the three primary colors based on an output signal of the switching means. Measuring display unit driving means for generating two driving signals and outputting the second driving signal, and the first connection to the switching means in the normal operation period. A switching means control section for generating and outputting the first control signal having a second level for instructing the second connection to the switching means during the correction period, Detecting the brightness of the three primary colors of the third image, which is a basic pattern for measurement, which is disposed opposite to the display surface of the measurement display unit and displayed by the measurement display unit in the correction period; An optical sensor for outputting a detected primary color brightness signal; and a level data of the second drive signal generated from the three primary color test pattern signals in the measurement display unit driving means. Conversion table data corresponding to the correction amount of the first drive signal necessary for correcting at least the white balance of the first image based on the detected three primary color brightness signals. And a gamma correction control unit that outputs the conversion table data as a second control signal, and the gamma correction unit performs the gamma correction based on the conversion table data provided by the second control signal. The gamma correction control unit is configured to: (a) Based on the level data and the detected three primary color brightness signals, the second drive signal and the brightness in the third image relating to the three primary colors. Means for generating data that gives an approximate curve indicating the relationship; and (b) a reference color of the three primary colors necessary for setting the ratio of the brightness of each of the three primary colors in the first image to a predetermined ratio. Provisional conversion table data providing second and third levels of the first drive signal for the other two colors with respect to the first level of the first drive signal for Means for generating based on the approximate curve data; (c) for the first level of the first drive signal; and (1) for the reference color, the first level of the first drive signal itself. (2) One of the other two colors is defined by the first level and the second level of the first drive signal, and the first and second levels are given as the first correction level of the first drive signal. A level within a range excluding the level is given as a second correction level of the first drive signal, and (3) the other one of the other two colors is the first level and the third level of the first drive signal. And means for determining the conversion table data on the basis of limit correction table data that provides a level within the range excluding the first and third levels as the third correction level of the first drive signal. That And Features .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
In the present embodiment, for convenience, a plasma display device is employed as an example of a color display device having a self-luminous element. Hereinafter, this embodiment will be described in detail with reference to the drawings.
[0012]
FIG. 1 is a plan view of a plasma display panel (hereinafter referred to as PDP: corresponding to a display panel) of the plasma display device according to the present embodiment as viewed from the front surface or the display surface side. As shown in FIG. 1, an image display unit 1 is disposed at the center of the PDP panel, and a peripheral region of the unit 1 forms a display panel peripheral unit 2 that does not display an image. However, the measurement display unit 3 is disposed in the right region in the display panel peripheral unit 2 as viewed from above the sheet of FIG. The image display unit 1 and the measurement display unit 3 are both manufactured in the same process and have the same structure. In addition, the drive circuits of the display units 1 and 3 (circuits 19 and 20 in FIG. 3 described later) also have the same circuit configuration. Therefore, the light emission characteristic of the image display unit 1 is the same as that of the measurement display unit 3, and the temporal change characteristic of the image display unit 1 is also the same as that of the measurement display unit 3. In addition, when saying "same" here, the concept of "substantially identical" is also included, and in that sense, the term "same" is a concept with a certain degree of tolerance (spread). is there.
[0013]
2 is a perspective plan view of the plasma display device having the PDP shown in FIG. 1 when the PDP is viewed from above (from the arrow direction A1 shown in FIG. 1). In FIG. 2, parts corresponding to the components shown in FIG. As shown in FIG. 2, an image display unit 1 and a measurement display unit 3 are formed on the display surface 4S side of the display panel 4 constituting the main body of the PDP. Alternatively, the optical sensor 5 is disposed opposite to the display surface 3S. Moreover, the light shielding cover 6 is disposed on the periphery of the display surface 3S so as to completely surround the periphery of the optical sensor 5. With this structure, light emitted from the measurement display unit 3 is shielded by the light shielding cover 6 and does not leak outside.
[0014]
FIG. 3 is a block diagram schematically showing a circuit configuration of the plasma display device according to the first embodiment. In FIG. 3 as well, parts corresponding to the components shown in FIGS. 1 and 2 are denoted by the same reference numerals.
[0015]
As shown in FIG. 3, the R signal input terminal 10 receives the R (red) signal VR, the G signal input terminal 11 receives the G (green) signal VG, and the B signal input terminal 12 receives the B ( The blue signal VB is received. Here, the input signals VR, VG, and VB are collectively referred to as “input three primary color signals” of three primary colors composed of R (red), G (green), and B (blue), and the three input terminals 10, 11. , 12 are also collectively referred to as “input terminals”.
[0016]
The R gamma correction circuit 13 has an input terminal connected to the R signal input terminal 10, a control terminal connected to the output terminal 21OT of the CPU 21 for receiving the second control signal VCT2, and an output terminal. Then, known gamma correction is performed on the R signal VR, and the corrected R signal (corrected R signal) V13R is output from the output terminal. Similarly, the G gamma correction circuit 14 has an input terminal connected to the G signal input terminal 11, a control terminal connected to the output terminal 21OT of the CPU 21 for receiving the second control signal VCT2, and an output terminal. Then, known gamma correction is performed on the G signal VG, and a corrected G signal (G signal to be corrected) V14G is output from its output terminal. Similarly, the B gamma correction circuit 15 has an input terminal connected to the B signal input terminal 12, a control terminal connected to the output terminal 21OT of the CPU 21 for receiving the second control signal VCT2, and an output terminal. And performing a known gamma correction on the B signal VB, and outputting a corrected B signal (corrected B signal) V15B from its output terminal. Here, the correction circuits 13, 14 and 15 for the three primary colors are collectively referred to as “gamma correction circuit”, and the correction signals V13R, V14G and V15B for the three primary colors are collectively referred to as “corrected three primary color signals”.
[0017]
The image display unit driving circuit 20 has an input terminal and an output terminal connected to the output terminal of the gamma correction circuit (13, 14, 15), and outputs the three primary color signals (V13R, V14G, V15B) to be corrected. Based on this, the first drive signals V20R, V20G, and V20B relating to the three primary colors are generated, and the first drive signals V20R, V20G, and V20B are output from the output terminals. The image display unit 1 has an input end connected to the output end of the image display unit drive circuit 20, and based on the first drive signals V20R, V20G, and V20B, the input three primary color signals VR, VG, and VB. The first image which is an image to be originally displayed given by is displayed.
[0018]
On the other hand, the white balance correction circuit system, which is the core of the present apparatus, includes the following elements 16-19, 3, 5, and 21. Hereinafter, each component of the white balance correction circuit system will be described.
[0019]
First, the test pattern generation circuit 16 is a unique screen data storage unit made of, for example, a ROM, and has an output end and a reception end that receives an address signal VA issued from the CPU 21. The circuit 16 has three primary color test pattern signals V16R, V16G, and V16B that give at least one type of measurement screen (fixed screen), and performs the three primary color test according to the read timing of the address signal VA. Pattern signals V16R, V16G, and V16B are output from their output terminals. In the present embodiment, for convenience of explanation, the circuit 16 provides three types of three primary color test pattern signals V16R, V16G, and V16B (various three primary colors) that respectively provide three types of measurement one screen (fixed screen). Test pattern signals are respectively called gray signals K1, K2, and K3).
[0020]
The average brightness generation circuit 17 has an input terminal and an output terminal connected to the output terminal of the gamma correction circuit (13, 14, 15), and the three primary color signals (V13R, V14G, V15B) to be corrected. ) Is averaged per screen to generate averaged three primary color signals V17R, V17G, and V17B that give the average brightness of each of the input three primary color signals (VR, VG, VB). Then, the averaged three primary color signals V17R, V17G, and V17B are output from the output terminals.
[0021]
The switching circuit 18 includes a first input terminal 18IT1 connected to the output terminal of the average brightness generation circuit 17, a second input terminal 18IT2 connected to the output terminal of the test pattern generation circuit 16, and a CPU 21. A control terminal for receiving the first control signal VCT1 emitted from the switching control unit and an output terminal 18OT are provided, and the first input terminal 18IT1 and the output terminal 18OT are controlled according to the level of the first control signal VCT1. And the second connection between the second input terminal 18IT2 and the output terminal 18OT are switched.
[0022]
The measurement display unit drive circuit 19 has an input terminal connected to the output terminal of the switching circuit 18 and an output terminal connected to the input terminal of the measurement display unit 3, and is emitted from the switching circuit. Based on the output signals V18R, V18G, and V18B related to the three primary colors, the second drive signals V19R, V19G, and V19B related to the three primary colors are generated, and the second drive signals V19R, V19G, and V19B are output from the output terminals.
[0023]
Here, the switching circuit control unit, which is one function circuit unit in the CPU 21, (i) during the normal operation period in which no white balance correction is performed, sets the first level (for example, L level) that commands the first connection. The first control signal VCT1 is output from the output terminal to the switching circuit 18, while (ii) after a normal operation period, in other words, between a normal operation period and a next normal operation period. In the correction period in which white balance correction is performed, the first control signal VCT1 having the second level (for example, H level) commanding the second connection is output from the output terminal to the switching circuit 18. As a result, the measurement display unit 3 displays (i) the second image having the brightness obtained by averaging the brightness of the first image over one screen during the normal operation period simultaneously with the display of the first image. On the other hand, (ii) three types of third images which are one measurement screen (fixed screen) provided by the gray signals K1, K2, and K3 in the correction period that is extremely short compared to the normal operation period. Are displayed sequentially. Therefore, the first and second light emission characteristics of the display units 1 and 3 are the same as each other, the first and second temporal change characteristics of the display units 1 and 3 are also the same, and the second image is displayed. Is an image having the average brightness of the first image, it can be considered that the deterioration over time of the actual display characteristics of the display units 1 and 3 during the normal operation period is substantially equal to each other. In addition, during the correction period, the measurement display unit 3 displays the third image as a fixed image that has nothing to do with the first image. This corresponds to the time required to detect the brightness of the third image by the optical sensor 5, and the detection time can be regarded as being relatively short compared to the normal operation period. Depending on the intervention of the correction period, it can be evaluated that there is no difference between the display characteristic aging degradation levels of the display units 1 and 3. The idea regarding this point (attention) is the backbone that supports the technical idea of the present embodiment.
[0024]
Note that the switching circuit control unit in the CPU 21 may generate the first control signal VCT1 at the second level in response to an external correction command from the user, or has a timer in the CPU 21. The switching circuit control unit may issue the second level first control signal VCT1 when the time of the timer reaches a predetermined correction time.
[0025]
The optical sensor 5 is disposed opposite to the display surface 3S of the measurement display unit 3 as described above with reference to FIG. 2, and at least a third image (displayed by the measurement display unit 3 during the correction period). The brightness of the three primary colors of the measurement basic pattern) is detected and the detected three primary color brightness signals V5R, V5G, and V5B are output from the output terminals. However, in the present embodiment, the optical sensor 5 performs not only the brightness detection of the third image but also the brightness detection of the second image in the normal operation mode. Output signals V5R, V5G, and V5B provide the brightness detection signal for the third image (in other words, only in the correction period during which the second level first control signal VCT1 is generated and output). V5R, V5G, and V5B are received / input. Alternatively, instead of this configuration, as indicated by a broken line in FIG. 3, the CPU 21 further outputs the first control signal VCT1 of the second level to the optical sensor 5 as an on / off control signal of the optical sensor 5. The optical sensor 5 may perform the detection operation only during the correction period.
[0026]
The CPU 21 is a core element of the white balance correction circuit system, and not only performs the operation as the switching circuit control unit described above, but also exhibits various functions represented by the following gamma correction control unit. In particular, the gamma correction control unit in the CPU 21 will be described as follows.
[0027]
That is, the gamma correction control unit has an input terminal connected to the output terminal of the optical sensor 5 and an output terminal connected to the control terminal of the gamma correction circuit (13, 14, 15), and the measurement display unit driving circuit. 19 holds the level data of the second drive signals V19R, V19G, V19B generated from the three primary color test pattern signals V16R, V16G, V16B. On the basis of the level data and the detected three primary color brightness signals V5R, V5G, and V5B received during the correction period, the same unit further includes a first drive signal necessary for correcting the white balance of the first image. Conversion table data corresponding to the correction amounts of V20R, V20G, and V20B is generated, and the conversion table data is output from the output terminal as the second control signal VCT2. As a result, the respective gamma correction circuits 13, 14, and 15 perform gamma correction based on the conversion table data provided by the second control signal VCT2 after receiving the second control signal VCT2.
[0028]
Next, the operation of the apparatus of FIG. 3 will be described in detail with reference to FIG. 5 which is a flowchart showing the operation and function of the CPU 21 as appropriate and also with reference to other drawings.
[0029]
First, the R signal input terminal 10, the G signal input terminal 11, and the B signal input terminal 12 receive the R signal VR, the G signal VG, and the B signal VB, respectively, and use the received input color signal for the corresponding color gamma. It outputs to the correction circuit 13-15. As a result, the R signal VR, the G signal VG, and the B signal VB are input to the corresponding color gamma correction circuits 13, 14, and 15, respectively. Each of the gamma correction circuits 13, 14, 15 is based on the input-output conversion table data for gamma correction set in advance in each circuit 13-15, and has a desired first brightness and white balance. A known gamma correction is applied to the corresponding color signal in the input three primary color signals (VR, VG, VB) so that an image display can be obtained in the image display unit 1. In addition, each of the gamma correction circuits 13, 14, and 15 outputs the corrected R signal V13R, the corrected G signal V14G, and the corrected B signal V15B after correction to the image display unit driving circuit 20 and the average brightness. The data is output to a generation circuit (substantially a portion for generating the second image signal) 17.
[0030]
As a result, one image display unit driving circuit 20 converts the received corrected three primary color signals V13R, V14G, and V15B into first driving signals V20R, V20G, and V20B in a data format suitable for displaying the first image. After conversion, the first drive signals V20R, V20G, and V20B of the three primary colors after generation are applied to electrodes (not shown) of the image display unit 1 in the PDP, and the image display unit 1 displays the first image. indicate.
[0031]
The other average brightness generation circuit 17 performs a process of calculating the average brightness of each of the received corrected three primary color signals V13R, V14G, and V15B. That is, the average brightness generation circuit 17 performs an averaging process on the levels of the corrected three primary color signals V13R, V14G, and V15B for one screen, and generates an average brightness for each color. Generate a one-screen average signal giving the level. Further, the circuit 17 averages each one-screen average signal for a predetermined time by passing the one-screen average signal of each color through a low-pass filter (not shown). The resulting signals are output signals V17R, V17G, and V17B that form a second image that exhibits an average brightness (light quantity) with respect to the first image. The output signals V17R, V17G, and V17B may be used as the one-screen average signal for each color (that is, low-pass filter processing is not performed).
[0032]
The output signal V17G relating to the G color calculated by such an average brightness generation circuit 17 is shown in the graph of FIG. In FIG. 4, the horizontal axis represents time, and the vertical axis represents the magnitude (level) of the averaged output signal V17G. A curve 26 indicated by a broken line in FIG. 4 is a one-screen average signal relating to G (green), and a curve 25 indicated by a solid line is obtained by further averaging the one-screen average signal 25 of G for a certain time. This is an output signal V17G obtained.
[0033]
Then, after performing the above-described brightness averaging process, the circuit 17 sends the output signals V17R, V17G (corresponding to the curve 25 in FIG. 4) and V17B for the three primary colors to the first input terminal 18IT1 of the switching circuit 18. Send.
[0034]
(A) In the following, first, the operation in the normal operation period (normal operation mode) will be described.
[0035]
Unless the CPU 21 detects a correction period start command, the CPU 21 determines that the present apparatus in FIG. 3 is in the normal operation mode, and outputs the first control signal VCT 1 of the first level to the control terminal of the switching circuit 18. Continue (step S1 in FIG. 5). As a result, in the normal operation mode, the switching circuit 18 continues to realize the first connection, and therefore passes the output signals V17R, V17G, and V17B of the average brightness generation circuit 17. As a result, the output signals V17R, V17G, and V17B for the respective colors that have passed through the switching circuit 18 are input to the measurement display unit drive circuit 19, and the circuit 19 converts the input output signals V17R, V17G, and V17B for the respective colors into Second drive signals V19R, V19G, and V19B in a data format suitable for image display are generated and applied to electrodes (not shown) of the measurement display unit 3, whereby the measurement display unit 3 displays the image. In contrast to the brightness of the first image of the unit 1, a second image having the average brightness is displayed.
[0036]
In this way, in the normal operation period, the measurement display unit 3 always displays the second image having an average brightness with respect to the display image of the image display unit 1, so that the average image without bias is displayed. The time-dependent change in the display unit 1 can be realized by the measurement display unit 3. That is, it can be considered that the temporal change of the image display unit 1 and the temporal change of the measurement display unit 3 during the normal operation period are substantially the same.
[0037]
(B) Next, the operation in the correction period following the normal operation period will be described.
[0038]
When a certain time has elapsed from the time of shipment of the display device from the factory, the display characteristics of the brightness for each color with respect to the input signal (second drive signal) of the measurement display unit 3 are different from each other. Since the relative shift amount of the brightness display characteristic is caused by a change with time of the display characteristic in the measurement display unit 3, the same relative shift amount is also applicable to the image display unit 1 in the same manner. To do. That is, when comparing the brightness level of each color with respect to a certain level of the input signal related to the reference color in the three primary colors, one of the other two colors is brighter (or darker) than that of the reference color, and the other The brightness of the color is brighter (or darker) than that of the reference color. For this reason, the luminance ratio of the three primary colors at the time of use is different from the adjusted ratio of the luminance of the three primary colors at the time of shipment from the factory, and the white light at the time of use becomes white with an unfavorable color temperature. Yes. Therefore, there is a need to correct the white balance in the image display unit 1 that has deviated from the adjustment value at the time of shipment from the factory to the preferred level through the adjustment or correction processing of the white balance of the third image in the measurement display unit 3. Arise. As described above, the display characteristics of both the display units 1 and 3 can be regarded as equivalent in the normal operation period, and the brightness detection period by the optical sensor 5 in the correction period is relatively small. Since this is a short and negligible time, it can be considered that there is no wrinkle in the change over time in the display characteristics of the display units 1 and 3 even during the correction period. Therefore, the white balance correction process of the third image in the measurement display unit 3 is equivalent to the white balance correction process in the image display unit 1.
[0039]
(B-1) Under the above-described state during the normal operation period, for example, when a certain amount of time has elapsed after the apparatus is turned on, when the apparatus is turned off, or when the apparatus is a television When the input three primary color signals are changed by switching the channels in FIG. 5 or when no image is displayed on the screen, the CPU 21 determines that it is the start of the correction period and has the second level. One control signal VCT1 is applied to the control terminal of the switching circuit 18 (step S2 in FIG. 5). As a result, the switching circuit 18 switches the connection relationship from the first connection to the second connection. Then, the CPU 21 outputs an address signal VA, which is a data read control signal, to the control terminal of the test pattern generation circuit 16, and as a result, the circuit 16 outputs the three primary color test pattern signals V16R, V16G, and V16B that it holds. Each screen is sequentially output to the switching circuit 18 side. As for the output timing of the three primary color test pattern signals (first gray signal K1) for giving the first fixed screen, the address signal VA for reading out the first gray signal K1 is used as the first control signal VCT1. The CPU 21 may generate and output before the change from the level to the second level. By the switching operation in the switching circuit 18, test pattern signals V16R, V16G, and V16B for R, G, and B colors are input to the measurement display drive circuit 19, and the circuit 19 displays a test pattern that is one fixed screen. The second drive signals V19R, V19G, and V19B having a data format suitable for the above are generated and output. As a result, the measurement display unit 3 displays the third image (fixed screen) of the first test pattern given by the first gray signal K1, and the photosensor 5 immediately displays each color in the first test pattern. Is detected, and the detected data V5R, V5G, and V5B are transmitted to the CPU 21. The CPU 21 receives and acquires the signals V5R, V5G, and V5B. Subsequently, the CPU 21 transmits the address signal VA to the test pattern circuit 16 again to read the second gray signal K2 from the circuit 16, and the third image (second image of the second test pattern given by the second gray signal K2). (Fixed screen) is displayed on the measurement display unit 3, and brightness (light quantity) data of each color in the second test pattern is acquired from the optical sensor 3. Further, the CPU 21 transmits the address signal VA to the test pattern circuit 16 to read out the third gray signal K3 from the circuit 16, and the third image (fixed screen) of the third test pattern given by the third gray signal K3. ) Is displayed on the measurement display unit 3, and brightness (light quantity) data of each color in the third test pattern is acquired from the optical sensor 3. Here again, the test pattern is a basic pattern for obtaining display characteristics of brightness with respect to the input signal (first drive signal) of the image display unit 1 (gray signals K1, K2, K3). Of course, the number of test patterns is arbitrary. If at least one test pattern is stored, it is theoretically possible to obtain an approximate curve and a conversion curve described below.
[0040]
Then, the CPU 21 returns the level of the first control signal VCT1 to the first level after completing the acquisition of the brightness (light quantity) data of each color in all the test patterns.
[0041]
(B-2) Next, the CPU 21 (gamma correction control unit) is based on the level data held therein and the detected three primary color brightness signals V5R, V5G, and V5B acquired from the optical sensor 5. Thus, data is generated that provides an approximate curve indicating the relationship between the second drive signal and the brightness in the third image for each of the three primary colors (step S3 in FIG. 5). In the following, from the viewpoint of simplifying the description, when the brightness of each color of R, G, B is equal, that is, when the ratio of the luminance of each color of R, G, B is 1: 1: 1, white balance (In general, it can be said that the white balance is good when the ratio of the luminances of the R, G, and B colors gives a predetermined ratio). This point is also valid in all the modifications described later, modifications thereof, and other embodiments.
[0042]
FIG. 6 shows an example of approximate curve data generated by the CPU 21, that is, an approximate curve that gives a display characteristic of brightness with respect to an input signal of the measurement display unit 3 when a certain time has elapsed from the time of factory shipment. ing. As shown in FIG. 6, it is understood that the brightness characteristics for the input signals V19R, V19G, and V19B of R, G, and B colors are shifted from each other. At the time of shipment from the factory, the brightness characteristics of the R, G, and B colors are adjusted to be the same, so the brightness levels of the three colors are on the same line. ) Is the darkest of the three colors, and then the brightness of G (green) is dark. For example, when the level data on the horizontal axis in FIG. 6 is the input signal K3, a magnitude relationship of (R brightness R3)> (G brightness G3)> (B brightness B3) is obtained. As a result, regarding the white balance of the third image and the first image, white light is dyed red (decrease in color temperature), and an unfavorable image is displayed.
[0043]
(B-3) Next, the CPU 21 (gamma correction control unit) sets the brightness ratio of each of the three primary colors in the first image, and thus the third image, to a predetermined ratio (here, 1: 1: 1). Required for the first level of the first drive signal related to the reference color (B (blue) in the example of FIG. 6) of the three primary colors (corresponding to the levels K1, K2, and K3 on the horizontal axis in the example of FIG. 6). Conversion table data that gives the second and third levels of the second drive signal for the other two colors (R (red) and G (green) in the example of FIG. 6) is generated based on the approximate curve data ( Step S4 in FIG.
[0044]
More specifically with reference to FIG. 6, in order to improve the white balance, the CPU 21 determines the brightness of each of the R, G, and B colors out of balance as the darkest B brightness in the current correction period. A conversion table for converting input signals of R, G, and B colors used in the gamma correction circuits 13, 14, and 15 is created so as to match the above. That is, according to the example of FIG. 6, the CPU 21 inputs the other two colors R and G that give the brightness (first level) B3 of the reference color B (blue) in the input signal K3 from the approximate curve of FIG. Determine the signals (second and third levels) K3R and K3G. Then, the calculated second and third levels K3R and K3B of the second drive signal are plotted on the conversion diagram of the input signal and the output signal of the gamma correction circuit shown in FIG. Similarly, the CPU 21 applies the second and third levels (K1R, K1G) of the second drive signals for the other two colors R and G to the first levels K1 and K2 of the second drive signal for the reference color B, respectively. (K2R, K2G) is also calculated from the approximate curve of FIG. 6, and the obtained second and third levels (K1R, K1G) and other second and third levels (K2R, K2G) are shown in FIG. By plotting as shown, a conversion curve is obtained from these calculated points. The conversion curve illustrated in FIG. 7 obtained by the above series of processing forms the conversion table data.
[0045]
Note that although the reference color is set to B (blue) as a preferred embodiment here, any one of R (red) and G (green) may be set as the reference color instead.
[0046]
(B-4) Thereafter, the CPU 21 transmits the obtained conversion table data as the second control signal VCT2 to the gamma correction circuits 13, 14, and 15 for each color (step S5 in FIG. 5).
[0047]
As a result, each of the gamma correction circuits 13, 14, 15 receives the conversion table data of the corresponding color given by the second control signal VCT2, and thereafter converts the input signal to the output signal based on the conversion table data. Perform (gamma correction).
[0048]
As a result, according to the present embodiment, while accurately reflecting the deterioration state accompanying the change over time of the display characteristics in the image display unit 1, in other words, while measuring the deterioration state correctly, a predetermined white balance is achieved. A good image display can be obtained. Furthermore, in the present embodiment, the measurement display unit 3 can realize display of an image very close to the actual display image (first image) in consideration of deterioration with time in the image display unit 1. The brightness detection of the display image (third image) performed in such a measurement display unit 3 is performed by increasing the brightness of the R, G, and B colors that determine the white balance of the actual display image (first image). Equivalent to accuracy measurement.
[0049]
(Modification 1)
The present modification relates to the improvement technique of the first embodiment. The gist of the technique is that the conversion table data calculated by the CPU 21 is “provisional conversion table data”, and then this temporary conversion table data is used. Is to limit the amount of correction given. That is, the CPU 21 (gamma correction control unit) uses the provisional conversion table data to set the first level of the second drive signal (and hence the first drive signal) itself for the reference color in (1) the three primary colors. The second drive signal (and hence the first drive signal) is given as the first correction level (no limit on the correction amount). (2) For one of the other two colors, the second drive signal (and hence the first drive signal) A level defined by one level and the second level and excluding the first and second levels is given as a second correction level of the second drive signal (and hence the first drive signal), and (3) the other two With respect to the other of the colors, a level within the range defined by the first level and the third level of the second driving signal (and hence the first driving signal) and excluding the first and third levels is set to the second driving signal (and therefore the first driving signal). 1 drive signal) as the third correction level It is, to calculate the "limit correction table data 'from the provisional conversion table data. Then, the CPU 21 determines conversion table data to be applied to the control end of the gamma correction circuit 13-15 based on the limit correction table data. In this case, the CPU 21 may set (i) the obtained limit correction table data as it is as final conversion table data, or (ii) a conversion table data limiter for each color R, G, B. A value (overcorrection prevention data) is provided, and further restriction correction table data is obtained by comparing the limiter value with the restriction correction table data and further imposing restrictions on the restriction correction table data. Thus, the new limit correction table data may be set as final conversion table data (for details, refer to the description of the modification of the present modification described later).
[0050]
As understood from the above description, the circuit configuration itself of the color display device according to the application of this modification is basically the same as that illustrated in FIG. 3 of the first embodiment, except for the internal function of the CPU 21. Just do it. Therefore, FIG. 3 is used in describing the present modification.
[0051]
Therefore, in the following, after describing the background (recognition of a new problem) that led to the idea of adding a restriction to the conversion curve obtained from the approximate curve data of FIG. A specific configuration will be described based on the flowchart of FIG. In this modification as well, as a preferred mode, the reference color among the three primary colors is set to B (blue).
[0052]
<Focus point>
Due to the measurement accuracy of the measurement system when creating the correction data, the brightness of the measurement display unit 3 may not be measured accurately. Here, the “measurement system” refers to the test pattern generation circuit 16-wiring-switching circuit 18-wiring-measurement display drive circuit 19-wiring-measurement display 3-light sensor 5-wiring-input in FIG. It is a system consisting of the end 21IT. Further, due to some disturbance such as the influence of propagation of electromagnetic waves from the outside (EMI noise), the brightness of the measurement display unit 3 may not be measured accurately. In order to prevent an apparent product abnormality from occurring in such a case, the CPU 21 needs to apply an appropriate amount of restriction to the correction amount of FIG. 7 calculated from the approximate curve of FIG. There is. That is, when the CPU 21 acquires a measurement value including noise caused by the above cause as a measurement result, the brightness with respect to the input signal indicated by the approximate curve in FIG. 6 is larger than the original brightness when there is no noise. Tend to. Therefore, the CPU 21 needs to limit the correction amount obtained from the measurement result in order to approximate the approximate curve data obtained from the measurement result to the original data.
[0053]
<Specific example>
FIG. 8 is a flowchart showing processing in the CPU 21 in this modification, and steps S1-S3 and S5 in FIG. 8 are the same as steps S1-S3 and S5 in FIG. 5, respectively. Therefore, hereinafter, steps S41 and S42 in FIG. 8 will be described.
[0054]
In this modification, the CPU 21 sends the provisional conversion table data calculated in step S41 (the calculation method is the same as the method described in step S4 in FIG. 5) to the gamma correction circuits 13, 14, and 15 as they are. Instead, restriction processing is performed on the provisional conversion table data to generate restriction correction table data (step S42). Here, as a typical example of the correction amount limitation, the CPU 21 performs provisional conversion table data (solid line for G in FIG. 7, two-dot chain line for R in FIG. 7) for each of G (green) and R (red). ) And a conversion table (that is, before correction) originally set in the B gamma correction circuit 15 (that is, a broken line with respect to B in FIG. 7) is connected to a middle position to give a curve that is formed. Data is calculated, and the limit correction table data is determined as final conversion table data to be transmitted to the gamma correction circuits 13, 14, and 15. That is, the CPU 21 performs arithmetic processing of (K1R + K1) / 2, (K2R + K2) / 2, and (K3R + K3) / 2 with respect to (a) R (red) from the provisional conversion table data shown in FIG. , (B) For G (green), calculation processing of (K1G + K1) / 2, (K2G + K2) / 2, and (K3G + K3) / 2 is performed, and R (red) and G (green) limit correction table data On the other hand, for (c) B (blue), the temporary conversion table data (K1, K2, K3) itself is set as the limit correction table data.
[0055]
In general, as described above, the CPU 21 outputs (a) the R (red) output signal KiRA (i is 1, 2, 3) after the restriction, K1R <K1RA <K1, K2R < What is necessary is just to set to the arbitrary value in the range of K2RA <K2 and K3R <K3RA <K3, and the same setting should just be performed also about the output signal of (b) G (green) after a restriction | limiting.
[0056]
Thereafter, the CPU 21 determines the limit correction table data as the conversion table data, and transmits the conversion table data to the respective gamma correction circuits 13, 14, 15 as the second control signal VCT2 (step S5). As a result, each of the gamma correction circuits 13, 14, and 15 operates so as to improve the white balance deteriorated due to the change with time by half based on the received conversion data of the corresponding color.
[0057]
As a result, according to this modification, it is possible to accurately determine the correction amount to be added without causing malfunction due to the accuracy of the measurement system or disturbance such as electromagnetic noise, and the display characteristics of the image display unit 1 can be determined. Regardless of the change over time, image display with good white balance can be realized.
[0058]
(Modification of Modification 1)
Further, the CPU 21 uses the conversion curve data (that is, the limiter value) stored in advance in the storage area in the CPU 21 as the conversion curve data calculated in step S42 in FIG. You may make it perform the further restriction | limiting of correction amount (double restriction | limiting) by performing a comparison process one by one. In this case, the limiter value serving as a comparison reference may be (1) an upper limit level for preventing the first image in the image display unit 1 from becoming too bright, and / or {Circle around (2)} Conversely, it may be a lower limit level for preventing the first image in the image display unit 1 from becoming too dark. By such data comparison processing, the CPU 21 overcorrects the output signal of the conversion curve (limit correction table data) calculated in step S42 over the output signal of the stored conversion curve that gives the limiter value in a certain input signal. When it is detected that the output signal value becomes, the CPU 21 executes a limiting process so that the value of the output signal corresponding to the input signal is stopped at the output signal value on the stored conversion curve.
[0059]
When the CPU 21 performs further correction amount limitation processing through comparison processing with the upper limit / lower limit limit value, the CPU 21 makes the first image after correction for change with time too bright or too dark. It is possible to prevent the occurrence of overcorrection.
[0060]
Note that the correction amount limiting method in the present modification can be applied not only to the first modification but also to the first embodiment described above, and to all the embodiments and modifications described later. The present invention can be applied to an example, and in any application example, a similar advantage of preventing occurrence of overcorrection can be obtained.
[0061]
(Modification 2)
The present modification is characterized in that the CPU 21 places a limit on the correction amount of the temporary conversion table data calculated from the approximate curve in FIG. Have. Therefore, in this modification, only the functions and operations of the CPU 21 in FIG. 3 are different from the first embodiment and its modification 1, and FIG. 3 is basically used in the description of this modification. . First, the general features of this modification will be described as follows.
[0062]
In other words, in this modification, the CPU 21 further includes a timer for measuring the elapsed time t from the factory shipment of the color display device of FIG. 3, and the gamma correction control unit in the CPU 21 includes the three primary colors. The first correction coefficient α1 with respect to the elapsed time t related to the first color (here red, for example) of the two colors excluding the reference color (here blue, for example) and the elapsed time related to the other second color (here green). The storage unit further includes correction coefficient table data for providing the second correction coefficient α2 for t. Here, the correction coefficients α1 and α2 in the correction coefficient table data are determined based on the time-varying characteristics of the measurement system, and the first and second correction coefficients α1 and α2 are both 0 or more and 1 or less. It is a value within the range (0 ≦ α1 ≦ 1, 0 ≦ α2 ≦ 1). The “measurement system” mentioned here is the same as described in the first modification.
[0063]
Further, the gamma correction control unit (a) three primary colors necessary for setting the ratio of the brightness of each of the three primary colors in the first image to a predetermined ratio (that is, necessary for obtaining a desired white balance). Providing second and third levels of the second drive signal (hence the first drive signal) for the first and second colors relative to the first level of the second drive signal (hence the first drive signal) for the medium reference color Temporary conversion table data is generated based on the approximate curve data. This is a step common to the first modification.
[0064]
Further, the gamma correction control unit (b) obtains the current elapsed time corresponding to the start of the correction period in accordance with the measurement result of the timer, and values of the first and second correction coefficients α1 and α2 at the current elapsed time. Is read from the correction coefficient table data.
[0065]
Further, the gamma correction control unit (c) with respect to the first level of the second drive signal (and hence the first drive signal), (1) the second drive signal (and hence the first drive signal) for the reference color. The first level itself is given as the first correction level of the second drive signal. {Circle around (2)} For one of the other two colors (first color), (1−first correction coefficient α1) × (second drive signal) Of the second drive signal (and hence the first drive signal) as the second correction level. The level given by the relational expression of (the first level of the first drive) + (first correction coefficient α1) × (second level of the second drive signal) And (3) For the other of the other two colors (second color), (1−second correction coefficient α2) × (first level of the second drive signal) + (second correction coefficient α2) × The level given by the relational expression (the third level of the second drive signal) is the third complement of the second drive signal (and hence the first drive signal). Limit correction table data given as a positive level is generated. Then, the gamma correction control unit determines final conversion table data based on the limit correction table data. In this case, the gamma correction control unit may determine (i) the limit correction table data itself as conversion table data (a specific example of the present modification described later), or (ii) a modification of the first modification. Can also be applied to this modification, and an additional correction amount limit can be applied through a one-by-one comparison process between the limit correction table data and the upper limit and / or lower limiter values, thereby providing an overcorrection prevention measure. good.
[0066]
Therefore, in the following, after describing the background (recognition of a new problem) that led to the idea of adding a restriction to the conversion curve obtained from the approximate curve data of FIG. A specific configuration will be described based on the flowchart of FIG. In this modification as well, as a preferred mode, the reference color among the three primary colors is set to B (blue).
[0067]
<Focus point>
The accuracy of the measurement values (V5R, V5G, V5B) obtained by the measurement may change over time due to the change over time of the measurement system when creating the correction data. This modification realizes a good white balance even in such a case.
[0068]
<Specific example>
In FIG. 9, steps S1-S3 correspond to steps S1-S3 related to FIG. 5, and step S41 corresponds to step S41 in FIG.
[0069]
In step S4A, as described above, the CPU 21 detects the elapsed time of use of the plasma display device from the time of shipment from the factory via the timer, and is empirical in advance in consideration of the time-varying characteristics of the measurement system. Or, the data of the first correction coefficient α1 related to R (red) and the second correction coefficient α2 related to G (green) obtained experimentally are held in the storage area as table data for the elapsed time of use. . Here, the upper limit of the usage elapsed time that can be handled by the correction coefficient table data is, for example, the average usage durability time of the apparatus or the warranty period of the apparatus. In any case, the CPU 21 holds all the first and second correction coefficients α1 and α2 for each elapsed time up to the upper limit of such elapsed time as table data.
[0070]
In step S4A, the CPU 21 obtains the elapsed time data corresponding to the start of the correction period from the measured value of the timer, and then calculates the values of the first and second correction coefficients α1 and α2 for the current elapsed time data. Extracted from the correction coefficient table data.
[0071]
In step S4B, for each of the first color (R) and the first color (G), the CPU 21 uses a correction coefficient corresponding to the provisional conversion data on the conversion curve in FIG. 7 corresponding to each color. The next correction limiting process is performed to generate a limited conversion curve. However, the CPU 21 does not perform any such correction restriction processing on the provisional conversion data on the conversion curve in FIG. 7 for the reference color (B), and converts the reference color (B) in FIG. The provisional conversion data itself on the curve is set as final conversion table data. That is, for (a) R (red), the CPU 21 limits the correction amount by multiplying the correction amount of the image by the first correction coefficient α1 for the elapsed time, that is, Ki−α1 × (Ki−KiR). = (1−α1) × Ki + α1 × KiR (i = 1, 2, 3) is used as the correction data that is generated as an output signal for the input signal Ki, and (b) G Similarly for (green), limit correction table data is generated in which the correction data given by the equation (1-α2) × Ki + α2 × KiG (i = 1, 2, 3) is used as the output signal for the input signal Ki. To do. For example, if the first correction coefficient α1 is 1, the limited conversion curve for R (red) is the same as the provisional conversion curve for R (red) in FIG. On the other hand, if the first correction coefficient α1 is 0, the limit conversion curve of R (red) is equal to the straight line of B (blue) in FIG. 7, and no correction is performed in this case. If the first correction coefficient α1 is 0.5, the limit conversion curve for R (red) exists in the middle of the provisional conversion curve for R (red) and the straight line for B (blue) in FIG. .
[0072]
In the next step S5, the CPU 21 transmits the limit correction table data as conversion table data, that is, as the second control signal VCT2, to each gamma correction circuit 13-15. The subsequent operation of each gamma correction circuit 13-15 is as described in the first embodiment. That is, each of the gamma conversion circuits 13, 14, and 15 receives the corresponding conversion table data, and thereafter performs conversion from the input signal to the output signal according to the conversion table data, and displays the image display with good white balance as the first image. Part 1 is displayed.
[0073]
As described above, in this modified example, the correction coefficient corresponding to the read current use elapsed time is manipulated in the conversion curve in FIG. Conversion table data). Therefore, according to the present modification, the CPU 21 displays the first image having a good white balance as in the first embodiment even when the measurement value accuracy fluctuates with time due to a change in the measurement system over time. It can be realized on the image display unit 1.
[0074]
(Modification 3)
The present modification relates to the improvement technique of the first embodiment, and particularly relates to the modification of the second modification. Therefore, since only the function of the CPU 21 is different from that in the second modification, FIG. 3 is basically used also in this modification.
[0075]
That is, as a feature point of this modification, the CPU 21 does not store the table data of the first and second correction coefficients for all the elapsed use times as in the modification 2, but the predetermined time has elapsed. Only the correction coefficient data at the elapsed time corresponding to each of the plurality of correction periods periodically performed each time is stored as table data discretely. With this configuration, in the present modification, the amount of correction coefficient data stored or stored in the CPU 21 can be significantly reduced as compared with the second modification. It can contribute to simplification.
[0076]
Note that the CPU 21 does not necessarily need to perform correction every regular time period. A certain correction period (first correction period) and the next correction period (second correction period) during the elapsed use time. Of course, the elapsed time may be set to an arbitrary time, and the same effect can be obtained in such a general case.
[0077]
Hereinafter, based on the flowchart of FIG. 10 which shows the process in CPU21, this modification is explained in full detail. Of the steps in FIG. 10, those unique to the present modification are steps S4AA and S6, and the other steps are as described above.
[0078]
The CPU 21 stores, in its internal storage area, an elapsed time (t1) corresponding to the first correction period, an elapsed time (t2) corresponding to the next correction period, and an elapsed time (t2) corresponding to the next correction period ( t3),..., correction coefficient table data composed of data of the first and second correction coefficients α1 and α2 for the elapsed time (tn) corresponding to the nth correction period (this table data is a modified example) Unlike the case of 2 (almost continuous data group), the data group is composed of discrete data). The first and second correction coefficients α1 and α2 mentioned here are those already described in the second modification, and both have values in the range of 0 or more and 1 or less.
[0079]
First, as the first correction period arrives, the CPU 21 generates the approximate curve data shown in FIG. 6 from the output signals V5R, V5G, and V5B of the optical sensor 5, and then obtains a predetermined white balance as shown in FIG. The temporary conversion curve data shown is generated (steps S1A-S41).
[0080]
The CPU 21 reads the first and second correction coefficients α1 and α2 corresponding to the elapsed time (t1) corresponding to the start time of the correction period from the correction coefficient table data (step S4AA), and then Based on the first and second correction coefficients α1 and α2, the correction amount limiting process is performed on the provisional conversion curve data shown in FIG. Specifically, the process is the same as the correction amount limiting process performed in step S4B in FIG. Thereafter, the CPU 21 determines conversion table data to be finally commanded to the gamma correction circuit based on the limit correction table data calculated in step S4B. At that time, the CPU 21 may determine the conversion table data by applying the technique of the modification example of the first modification (further correction limiting process based on the limiter value). The correction table data itself is determined as conversion table data.
[0081]
Thereafter, the CPU 21 continues to monitor whether or not the current elapsed time indicated by the timer included therein is equal to the elapsed time (t2) corresponding to the next correction period, which is also included therein (step S6). When the current elapsed time reaches the elapsed time (t2), the CPU 21 obtains the measurement data from the optical sensor 5 again, creates the approximate curve data in FIG. 6, and subsequently provisional in FIG. Similar conversion table data is generated, and the same correction amount limiting process is executed after reading out the first and second correction coefficients α1 and α2 corresponding to the elapsed time (t2).
[0082]
Thereafter, as shown in FIG. 10, the CPU 21 performs the same correction amount limiting process and conversion table data determination / output process every time the correction period arrives.
[0083]
As described above, according to the present modification, the correction amount is set at regular intervals, so that it is not necessary to always operate the circuit, so that the circuit operation can be simplified and the correction that the CPU 21 has therein. The coefficient table can also be simplified, and as a result, the first image having a good white balance in consideration of the change over time of the measurement system can be easily displayed on the image display unit 1.
[0084]
(Modification 4)
This modified example relates to the improved technique of modified example 3, and the feature point is the progress between a certain correction period (first correction period) and the next correction period (second correction period) in modified example 3. During the time, the CPU 21 executes the correction amount limiting process and the gamma correction while gradually increasing the values of the first and second correction coefficients toward the corresponding extracted value at the elapsed time corresponding to the first correction period. The point is that transmission of conversion table data to the circuit is continued. Therefore, also here, the specific example is described below, using the circuit diagram of FIG. Note that it is not essential to gradually increase the values of the first and second correction coefficients, and at least the first and second preceding correction coefficients α1A and α2A smaller than the extracted first and second correction coefficients α1 and α2 are set. The used first and second preceding restriction processing (processing preceding the first and second restriction processing using the first and second correction coefficients α1 and α2) may be performed at least once.
[0085]
FIG. 11 is a flowchart mainly showing the operations and functions of the CPU 21 in the present modification, and features different from the modification 3 exist in steps S4AA1 to S4AA3. In FIG. 11, steps having the same number as the step number already appearing have the same contents as the corresponding steps described above, and therefore, in the present modification, their description is omitted. .
[0086]
The CPU 21 gradually increases the correction coefficient toward the original value during a certain correction period (first correction period) and the next correction period (second correction period), and generates and outputs a conversion data table. Eventually, the original conversion coefficient value read from the correction coefficient table data is used to generate and output a desired conversion data table.
[0087]
In step S4AA1, the CPU 21 is more sufficient than the first and second correction coefficients α1 and α2 read from the correction coefficient table data corresponding to the start time (for example, tA) of the correction period (first correction period). Are set to first and second correction coefficients (also referred to as first and second preceding correction coefficients) α1A and α2A, respectively.
[0088]
After that, the CPU 21 performs the step S4B described in the modified example 3 using the first and second correction coefficients α1A (= α10) and α2A (= α20), and performs the limit correction table data (the preceding limit correction table). The limit correction table data is transmitted to the gamma correction circuit 13-15 for each color as conversion table data (second control signal VCT2).
[0089]
In step S4AA2, the CPU 21 sets arbitrary increase values Δα1 and Δα2 to the first and second correction coefficients α1A (= α10) and α2A (= α20), respectively (the increase values Δα1 and Δα2 may be constant values each time, or The first and second correction coefficients α1A and α2A are gradually increased by adding a different value each time. Then, the CPU 21 sets the increased first and second correction coefficients α1A + Δα1 and α2A + Δα2 to new first and second correction coefficients α1A and α2A, respectively, and these new first and second correction coefficients α1A and α2A. Then, the step S4B already described in the third modification is performed to calculate the limit correction table data, and the limit correction table data is used as the conversion table data (second control signal VCT2) for each color gamma correction circuit 13- 15 to send.
[0090]
Then, the CPU 21 repeats such processing to gradually increase the first and second correction coefficients and update the conversion table data in a direction to gradually increase, and in step S4AA3, the increased first And when it is detected that the second correction coefficients α1A + Δα1, α2A + Δα2 have finally reached the values of the first and second correction coefficients α1, α2 read from the correction coefficient table data corresponding to the elapsed time tA. The increase processing of the first and second correction coefficients is stopped, and the original values of the final first and second correction coefficients α1 and α2 are used to perform step S4B already described in the modification 3 and should originally exist. Limit correction table data is calculated, and the limit correction table data is converted into original conversion table data (second control signal VCT2) at time tA for each color gun. And transmits it to the correction circuit 13-15.
[0091]
The above processing will be described in more detail below using specific numerical values. As an example, the description will focus on the first correction coefficient α1 (= 1) for R (red). That is, in the first stage of a certain correction period, the CPU 21 transmits conversion data obtained by multiplying the correction data in FIG. 7 by the correction coefficient 0.2 to the gamma correction circuits 13, 14, and 15 for each color. Thereafter, after the CPU 21 detects that a predetermined time has elapsed, the CPU 21 slightly increases the correction coefficient from 0.2 to 0.5, and adds the corrected new correction coefficient to the correction data. Multiplying by 0.5, the obtained conversion data is transmitted again to the gamma correction circuits 13, 14 and 15 for each color. After that, the CPU 21 detecting that a certain time has passed further increases the correction coefficient value from 0.5 to 1 which is the final value, and then multiplies the correction data by the original correction coefficient 1, The conversion data obtained as a result is transmitted to each of the gamma correction circuits 13, 14, and 15 again. Thereafter, the CPU 21 does not update the conversion table data until the next correction period comes.
[0092]
In this way, in this modification, the conversion data to be sent to the gamma correction circuits 13, 14, 15 is gradually increased.
[0093]
With the above configuration, it is possible to prevent the white balance itself from being changed suddenly by the correction of the gamma correction circuit, thereby realizing a good white balance. In other words, instead of setting the calculated correction amount all at once, the correction amount is gradually increased over a certain period of time, and the conversion data is finally set to the calculated correction amount. The correction works slowly, and a good white balance without any sense of incongruity can be easily obtained.
[0094]
(Embodiment 2)
The present embodiment improves the first embodiment and aims to optimize not only white balance but also luminance.
[0095]
That is, when the plasma display device is used for a certain period of time after shipment from the factory, the brightness of each color of R (red), G (green), and B (blue) is higher than that at the time of shipment from the factory. It is dark. As a result, the brightness and white balance in the plasma display device after shipment from the factory are both worse than the brightness and white balance at the factory shipment.
[0096]
Therefore, in the present embodiment, the brightness data of each color adjusted at the time of shipment from the factory is stored in advance by the CPU 21, and the R measured and detected from the third image at that time in a certain correction period after the shipment from the factory. Conversion curve data (gamma) to be applied to the gamma correction circuit so that the brightness data of each color (red), G (green), and B (blue) is equal to the brightness data of each color adjusted at the time of shipment from the factory. The CPU 21 generates a conversion table of input signals and output signals of the correction circuit. Thus, since the difference between the present embodiment and the first embodiment is exclusively in the operation and function of the CPU 21, the circuit diagram of FIG. 3 is also used in this embodiment.
[0097]
The general features of the present embodiment are as follows. That is, the gamma correction control unit of the CPU 21 sets the second drive signals V19R, V19G, and V19B (accordingly, the first drive signals V20R, V20G, and V20B) at the time of shipment from the factory where the white balance and luminance of the first image have been adjusted. ) “Factory shipment table data” (corresponding to a thick solid line in FIG. 13 described later) that gives the brightness of each of the three primary colors to the storage unit. In addition, the gamma correction control unit of the CPU 21 is based on factory shipment table data, level data (input signals K1, K2, and K3 in FIG. 13 described later) and detected three primary color brightness signals V5R, V5G, and V5B. The conversion table data is generated so that the white balance and brightness of the third image (and hence the first image) in the correction period are equal to the white balance and brightness of the third image (and hence the first image) at the time of shipment from the factory, respectively. . Hereinafter, the operation of the CPU 21 as the gamma correction control unit will be described in detail in accordance with steps S3A, S4A, and S5 in the flowchart of FIG.
[0098]
In step S3A of FIG. 12, the CPU 21 detects (1) the detection levels V5R, V5G, V5B of the optical sensor 5 in each test pattern K1, K2, K3, and (2) level data (input signal K1, FIG. Based on (K2, K3), data that gives approximate curves of R (red), G (green), and B (blue) colors shown in FIG. 13 similar to FIG. 6 is generated. As can be understood from FIG. 13, when compared with the brightness (light quantity) at the time of shipment from the factory, which is displayed by a thick solid line, the third image of the measurement display unit 3, and thus the B of the first image in the image display unit 1. (Blue) is the darkest of the three primary colors, and therefore the brightness of B (blue) that has deteriorated over time is the largest of the three primary colors in order to restore the brightness to the factory default. There is a need to input and consume power (that is, the level of the input signal after correction becomes larger). Similarly, in the present embodiment, for convenience of description, when the brightness of each color of R (red), G (green), and B (blue) is at the same level (brightness ratio is 1). 1: 1), and the white balance is in a good state.
[0099]
Next, in step S4A of FIG. 12, the CPU 21 (1) approximate curve data of each color of R (red), G (green) and B (blue) in FIG. 13, and (2) a thick solid line in FIG. The input signal of each color that can realize the brightness at the time of factory shipment is obtained by the comparison process with the table data at the time of factory shipment displayed in the above, and the conversion curve table shown in FIG. 14 is created. In FIG. 14, as a reference, a conversion straight line with respect to the factory shipment table data itself of the thick solid line in FIG. 13 is displayed as a thick solid line. Then, the CPU 21 transmits the created conversion table data for each color as the second control signal VCT2 to the gamma correction circuits 13, 14, and 15 for each color (step S5).
[0100]
The gamma conversion circuits 13, 14, and 15 for each color receive the conversion table data VCT 2 and thereafter perform conversion from an input signal to an output signal according to the conversion data. As a result, the brightness and white balance of each color of R (red), G (green), and B (blue) at the time of use after shipment from the factory are respectively changed to the brightness and white balance of each color at the time of shipment from the factory. A matched and good image display is obtained in the image display unit 1.
[0101]
(Modification 5)
The present modification is obtained by applying the improved technique of the first modification to the second embodiment. Therefore, the object is to add the effect of the first modification to the technique of the second embodiment. Also in this modification, referring to FIG. 3 described above, first, the characteristic points of this modification will be generalized and described as follows.
[0102]
The gamma correction control unit of the CPU 21 relates to each of the three primary colors based on (a) level data (input signals K1, K2, and K3 in FIGS. 13 and 14) and detected three primary color brightness signals V5R, V5G, and V5B. After generating the approximate curve data of FIG. 13 showing the relationship between the second drive signals V19R, V19G, V19B and the brightness in the third image, (b) the white balance and the luminance of the first image in the correction period are shipped from the factory, respectively. Second drive signals for the three primary colors (e.g., R), second color (e.g., G), and third color (e.g., B) required to equal the white balance and brightness of the first image at the time, Accordingly, the first, second, and third levels of the first drive signals V20R, V20G, and V20B (for example, in the example of FIG. Provisional values which provide first, second and third correction levels (for example, output signals K3R, K3G, K3B in the example of FIG. 13) for the input signal K3). The conversion table data is generated based on the factory shipment table data and the approximate curve data.
[0103]
(C) Further, the gamma correction control unit of the CPU 21 (1) for the first color (R), the first level (for example, K3 in FIG. 14) and the first correction level of the first drive signal V20R at the time of factory shipment. (For example, K3R in FIG. 14) and the level within the range excluding the first level and the first correction level at the time of factory shipment is the first level relative to the first level (for example, K3 in FIG. 14). This is given as the first limit correction level of the drive signal. Also, the gamma correction control unit {circle around (2)} for the second color (G), the second level (for example, K3 of FIG. 14) and the second correction level (for example, K3G of FIG. 14) of the first drive signal at the time of factory shipment. ) And within the range excluding the second level and the second correction level at the time of factory shipment, the second limit of the first drive signal with respect to the second level at the time of factory shipment (for example, K3 in FIG. 14). Give as correction level. Further, the gamma correction control unit (3) for the third color (B), the third level (for example, K3 in FIG. 14) and the third correction level (for example, K3B in FIG. 14) of the first drive signal at the time of factory shipment. ) And within the range excluding the third level and the third correction level at the time of factory shipment, the third limit of the first drive signal with respect to the third level at the time of factory shipment (for example, K3 in FIG. 14). Give as correction level. Then, the gamma correction control unit generates limit correction table data based on at least the first to third limit correction levels, and then determines conversion table data based on the limit correction table data (then At this time, the modification example of the first modification may be applied).
[0104]
Hereinafter, this modification will be described more specifically in accordance with the flowchart of FIG. However, the description will focus on the points of FIG. 15 different from FIG. 8 described above.
[0105]
In step S41A of FIG. 15, the CPU 21 provisionally converts the conversion line data of each color shown in FIG. 14 by comparing the factory shipment table data displayed by the thick solid line of FIG. 13 and the approximate curve data of each color of FIG. Generated as static conversion table data.
[0106]
Then, in step S42A, the CPU 21 performs the same processing as that in step S42 in FIG. 8 on each color R (red), G (green), and B (blue) to generate limit correction table data. As a result, for example, in the correction restriction for B (blue), the conversion straight line given by the B (blue) color restriction correction data corresponds to the position data on the straight line displayed by the broken line in FIG. It becomes a straight line displayed by intermediate value data with position data on the straight line displayed by a thick solid line. The same applies to the other two color correction restrictions.
[0107]
As described above, according to this modification, it is possible to display on the image display unit 1 the first image having good luminance and white balance that does not deteriorate due to malfunction such as disturbance.
[0108]
(Modification 6)
The present modification is obtained by applying the improvement technique of the modification 2 to the second embodiment. Therefore, the object is to add the effect of the modification 2 to the technique of the second embodiment. Also in this modification, using the above-described FIG. 3, first, the conversion curve data is limited based on the characteristic points of this modification, that is, the first to third correction coefficients of the first to third colors. In general, the idea is as follows based on the actual processing.
[0109]
In other words, the gamma correction control unit of the CPU 21 stores “correction coefficient table data for providing first, second, and third correction coefficients for the first, second, and third colors of the three primary colors with respect to the elapsed time”. These correction coefficient table data are determined based on the light-time change characteristics of the measurement system, as in the second modification, and the first, second, and third correction coefficients are All are values in the range of 0 or more and 1 or less.
[0110]
Then, the gamma correction control unit of the CPU 21 performs (a) provisional conversion table data that gives the first, second, and third correction levels for the first, second, and third colors of the three primary colors as factory table data. And (b) obtaining the current elapsed time corresponding to the start of the correction period according to the measurement result of the timer, and obtaining the first, second and third correction coefficients for the current elapsed time. Is read from the correction coefficient table data, and the following correction limiting process (c) is executed on the first, second and third correction levels using these correction coefficients.
[0111]
That is, the gamma correction control unit of the CPU 21 (1) for the first color (for example, R), (1−first correction coefficient) × (first level of the first drive signal at the time of factory shipment) + (first The level given by the relational expression of (correction coefficient) × (first correction level of the first drive signal) is given as the first limit correction level of the first drive signal with respect to the first level of the first drive signal at the time of factory shipment. . Further, the gamma correction control unit {circle around (2)} for the second color (for example, G), (1−second correction coefficient) × (second level of the first drive signal at the time of factory shipment) + (second correction coefficient) ) × (second correction level of the first drive signal) is given as a second limit correction level of the first drive signal with respect to the second level of the first drive signal at the time of factory shipment, and {Circle around (3)} For the third color (for example, B), (1−third correction coefficient) × (third level of the first drive signal at the time of factory shipment) + (third correction coefficient) × (first drive signal of The level given by the relational expression (third correction level) is given as the third limit correction level of the first drive signal with respect to the third level of the first drive signal at the time of factory shipment. Then, the gamma correction control unit of the CPU 21 uses these limit correction levels to generate limit correction table data that gives a limited conversion curve, and determines conversion table data based on the limit correction table data.
[0112]
Here, FIG. 16 is a flowchart showing the above-described operation of the CPU 21 (gamma correction control unit) in the present modification in accordance with the cases of FIGS. 13 and 14, and corresponds to FIG. 9.
[0113]
As described above, in the present modification, the correction amount is appropriately set by operating the first to third correction coefficients α1, α2, and α3 corresponding to the read current use elapsed time to the provisional conversion curve of FIG. The conversion curve (conversion table data) for performing the actual correction is limited. For this reason, according to this modification, the CPU 21 has good luminance and good white balance as in the second embodiment, even when the measurement value accuracy fluctuates with time due to the change of the measurement system over time. The first image can be realized on the image display unit 1.
[0114]
(Modification 7)
The present modification is obtained by applying the improvement technique of the third modification to the second embodiment (a point in which correction is periodically performed). Therefore, the effect of the third modification is also added to the technique of the second embodiment. The purpose is to do. Also in this modification, the above-described FIG. 3 is used.
[0115]
FIG. 17 is a flowchart corresponding to FIG. 10 and shows the operation of the CPU 21 (gamma correction control unit) in this modification. In the operation shown in FIG. 17, processing corresponding to the existence of correction coefficients for each of the three primary colors is only added to the operation shown in FIG. 10, and the basic concept remains unchanged. The description of the operation in FIG. 17 is omitted.
[0116]
According to this modification, since the correction amount is set every certain period of time, it is not necessary to always operate the circuit, so that the circuit operation can be simplified and the correction coefficient table that the CPU 21 has is also simple. As a result, it is possible to easily display the first image having both good luminance and good white balance on the image display unit 1 in consideration of the change over time of the measurement system. Become.
[0117]
(Modification 8)
This modification is an improvement technique of the modification 4 of the second embodiment (periodic correction, and gradually increases the correction coefficient toward the original coefficient value between a certain correction period and the next correction period. Therefore, an object of the present invention is to make it possible to realize the effect of the modification 4 also in the technique of the second embodiment. Also in this modification, the above-described FIG. 3 is used.
[0118]
Here, FIG. 18 is a flowchart corresponding to FIG. 11 and shows the operation of the CPU 21 (gamma correction control unit) in this modification. In the operation shown in FIG. 18, processing corresponding to the existence of correction coefficients for each of the three primary colors is only added to the operation shown in FIG. 11, and the basic concept remains unchanged. The description of the operation in FIG. 18 is omitted.
[0119]
According to this modification, it is possible to prevent the luminance and white balance from changing suddenly by the correction of the gamma correction circuit, and it is possible to realize good luminance and good white balance. In other words, instead of setting the calculated correction amount all at once, the correction amount is gradually increased over a certain period of time, and the conversion data is finally set to the calculated correction amount. The correction works slowly, and it is possible to easily obtain good brightness and good white balance without any sense of incongruity.
[0120]
(Other variations)
1) Regarding the brightness measurement by the optical sensor 5 described in the first and second embodiments and the modifications 1-8, the measurement results V5R, V5G, and V5B are not set by one measurement, but the optical sensor 5 may measure the brightness several times and take the average value of the measured values, for example, to derive the measured value data V5R, V5G, V5B. Good brightness measurement is possible.
2) Although Embodiments 1 and 2 and Modifications 1-8 describe plasma display devices, similarly, CRT displays using self-luminous elements, inorganic / organic EL displays, and other display color display devices The subject matter of the present invention can also be applied to, and in any case, good white balance or good brightness and white balance can be realized.
[0121]
(Appendix)
While the embodiments of the present invention have been disclosed and described in detail above, the above description exemplifies aspects to which the present invention can be applied, and the present invention is not limited thereto. In other words, various modifications and variations to the described aspects can be considered without departing from the scope of the present invention.
[0122]
【The invention's effect】
The color display device according to the present invention has the following effects. In other words, in the normal operation period, the measurement display unit displays the second image having the average brightness of the original first image to be displayed on the image display unit. The change in display characteristics over time can be reflected almost equally in the change in display characteristics over time in the measurement display section. Under such conditions, the brightness detection data of the measurement display section measured during the next correction period Can be regarded as the brightness of the first image in the image display unit that has undergone a change over time for substantially the same period. In particular, the shorter the measurement period in the correction period, the more prominent this identity imitation is. Therefore, in this device, it is possible to accurately correct the white balance of the original image to be displayed according to the measured brightness data while accurately reflecting the actual deterioration state of the display screen. A simple white balance can be obtained easily.
[Brief description of the drawings]
FIG. 1 is a plan view showing a plasma display panel of a plasma display device according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing a plasma display device according to Embodiment 1 of the present invention.
FIG. 3 is a block diagram showing a plasma display apparatus according to Embodiment 1 of the present invention.
FIG. 4 is a diagram showing a G output signal of an average brightness circuit according to the first embodiment of the present invention.
FIG. 5 is a flowchart showing the operation of the CPU according to Embodiment 1 of the present invention.
FIG. 6 is a diagram showing an approximate curve that gives characteristics of an input signal and brightness of a measurement display unit according to Embodiment 1 of the present invention.
FIG. 7 is a diagram showing input / output characteristics (conversion curves) in the first embodiment of the present invention.
FIG. 8 is a flowchart showing the operation of a CPU in Modification 1 of the present invention.
FIG. 9 is a flowchart showing the operation of a CPU in Modification 2 of the present invention.
FIG. 10 is a flowchart showing the operation of a CPU in Modification 3 of the present invention.
FIG. 11 is a flowchart showing the operation of a CPU in Modification 4 of the present invention.
FIG. 12 is a flowchart showing the operation of the CPU in the second embodiment of the present invention.
FIG. 13 is a diagram showing an approximate curve that gives characteristics of an input signal and brightness of a measurement display unit according to Embodiment 2 of the present invention;
FIG. 14 is a diagram showing a conversion curve in Embodiment 2 of the present invention.
FIG. 15 is a flowchart showing the operation of a CPU in Modification 5 of the present invention.
FIG. 16 is a flowchart showing the operation of a CPU in Modification 6 of the present invention.
FIG. 17 is a flowchart showing the operation of a CPU in Modification 7 of the present invention.
FIG. 18 is a flowchart showing the operation of a CPU in Modification 8 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image display part, 2 Display panel peripheral part, 3 Measurement display part, 4 Display panel, 5 Optical sensor, 6 Light shielding cover, 10 R signal input terminal, 11 G signal input terminal, 12 B signal input terminal, 13 R gamma Correction circuit, 14 G gamma correction circuit, 15 B gamma correction circuit, 16 test pattern generation circuit, 17 average brightness generation circuit, 18 switching circuit, 19 measurement display drive circuit, 20 image display drive circuit, 21 CPU .

Claims

Gamma correction means for performing gamma correction on the input three primary color signals and outputting the corrected three primary color signals after correction;
Image display unit driving means for generating a first drive signal for the three primary colors based on the corrected three primary color signals of the gamma correction means and outputting the first drive signal;
An image display unit for displaying a first image given by the input three primary color signals based on the first drive signal;
The second light emission characteristic is the same as the first light emission characteristic of the image display unit, and the second time change characteristic is the same as the first time change characteristic of the image display unit, and the second image is displayed in the normal operation period. On the other hand, a measurement display unit that displays the third image in the correction period;
Averaging processing for one screen is performed on each of the three primary color signals to be corrected by the gamma correction unit to generate an average three primary color signal that gives an average brightness of each of the three input primary color signals. Average brightness calculating means for outputting the averaged three primary color signals;
A test pattern generating means for holding at least one primary color test pattern signal for giving one screen for measurement and outputting the three primary color test pattern signal;
A first connection for outputting the averaged three primary color signals output from the average brightness calculation means according to the level of the first control signal, or the three primary color test output from the test pattern generation means. Switching means for switching between the second connection for outputting the pattern signal;
A measurement display unit driving means for generating a second driving signal for the three primary colors based on the output signal of the switching means and outputting the second driving signal;
In the normal operation period, the switching means has a first level for instructing the first connection, and in the correction period, the switching means has a second level for instructing the second connection. A switching means controller that generates and outputs a first control signal;
Detecting the brightness of the three primary colors of the third image, which is a basic pattern for measurement, which is disposed opposite to the display surface of the measurement display unit and displayed by the measurement display unit in the correction period; An optical sensor for outputting a detected primary color brightness signal;
The measurement display unit driving means has level data of the second driving signal generated from the three primary color test pattern signals, and at least based on the level data and the detected three primary color brightness signals A gamma correction control unit that generates conversion table data corresponding to the correction amount of the first drive signal necessary for correcting the white balance of the first image, and outputs the conversion table data as a second control signal. ,
The gamma correction means is a color display device that performs the gamma correction based on the conversion table data given by the second control signal,
The gamma correction control unit
(A) Based on the level data and the detected three primary color brightness signals, means for generating data that gives an approximate curve indicating the relationship between the second drive signal and the brightness in the third image for the three primary colors When,
(B) Other two to the first level of the first drive signal relating to the reference color of the three primary colors necessary for setting the ratio of the brightness of each of the three primary colors in the first image to a predetermined ratio. Means for generating provisional conversion table data for providing second and third levels of the first drive signal relating to color based on the approximate curve data;
(C) With respect to the first level of the first drive signal, (1) for the reference color, the first level of the first drive signal itself is given as a first correction level of the first drive signal; (2) For one of the other two colors, a level within the range defined by the first level and the second level of the first drive signal and excluding the first and second levels is set to the first drive. And (3) the other of the other two colors is defined by the first level and the third level of the first drive signal, and the first and third levels. And means for determining the conversion table data based on limit correction table data that gives a level within a range excluding as a third correction level of the first drive signal.
Color display device.

Gamma correction means for performing gamma correction on the input three primary color signals and outputting the corrected three primary color signals after correction;
Image display unit driving means for generating a first drive signal for the three primary colors based on the corrected three primary color signals of the gamma correction means and outputting the first drive signal;
An image display unit for displaying a first image given by the input three primary color signals based on the first drive signal;
The second light emission characteristic is the same as the first light emission characteristic of the image display unit, and the second time change characteristic is the same as the first time change characteristic of the image display unit, and the second image is displayed in the normal operation period. On the other hand, a measurement display unit that displays the third image in the correction period;
Averaging processing for one screen is performed on each of the three primary color signals to be corrected by the gamma correction unit to generate an average three primary color signal that gives an average brightness of each of the three input primary color signals. Average brightness calculating means for outputting the averaged three primary color signals;
A test pattern generating means for holding at least one primary color test pattern signal for giving one screen for measurement and outputting the three primary color test pattern signal;
A first connection for outputting the averaged three primary color signals output from the average brightness calculation means according to the level of the first control signal, or the three primary color test output from the test pattern generation means. Switching means for switching between the second connection for outputting the pattern signal;
A measurement display unit driving means for generating a second driving signal for the three primary colors based on the output signal of the switching means and outputting the second driving signal;
In the normal operation period, the switching means has a first level for instructing the first connection, and in the correction period, the switching means has a second level for instructing the second connection. A switching means controller that generates and outputs a first control signal;
Detecting the brightness of the three primary colors of the third image, which is a basic pattern for measurement, which is disposed opposite to the display surface of the measurement display unit and displayed by the measurement display unit in the correction period; An optical sensor for outputting a detected primary color brightness signal;
The measurement display unit driving means has level data of the second driving signal generated from the three primary color test pattern signals, and at least based on the level data and the detected three primary color brightness signals A gamma correction control unit that generates conversion table data corresponding to the correction amount of the first drive signal necessary for correcting the white balance of the first image, and outputs the conversion table data as a second control signal. ,
The gamma correction means is a color display device that performs the gamma correction based on the conversion table data given by the second control signal,
A timer for measuring the elapsed time from a predetermined time point;
The gamma correction control unit
Means for providing a first correction coefficient and a second correction coefficient for the elapsed time, and storing correction coefficient table data determined based on a time-dependent change characteristic of a measurement system including the measurement display unit;
(A) Based on the level data and the detected three primary color brightness signals, means for generating data that gives an approximate curve indicating the relationship between the second drive signal and the brightness in the third image for the three primary colors When,
(B) Other two to the first level of the first drive signal relating to the reference color of the three primary colors necessary for setting the ratio of the brightness of each of the three primary colors in the first image to a predetermined ratio. Means for generating provisional conversion table data for providing second and third levels of the first drive signal relating to color based on the approximate curve data;
(C) Means for obtaining a current elapsed time corresponding to the start of the correction period according to the measurement result of the timer and reading the values of the first and second correction coefficients at the current elapsed time from the correction coefficient table data When,
(D) with respect to said first level of said first drive signal, (1) gives the first level itself with respect to the reference color before Symbol first driving signal as a first correction level of the first driving signal (2) For one of the other two colors, a first limit level obtained by executing a first limit process using the first correction coefficient on the second level of the first drive signal is set to the first level. And (3) with respect to the other of the other two colors, the second restriction process using the second correction coefficient is applied to the third level of the first drive signal. Means for generating limit correction table data that gives a second limit level obtained by execution as a third correction level of the first drive signal;
(E) further comprising means for determining the conversion table data based on the limit correction table data.
Color display device.

Gamma correction means for performing gamma correction on the input three primary color signals and outputting the corrected three primary color signals after correction;
Image display unit driving means for generating a first drive signal for the three primary colors based on the corrected three primary color signals of the gamma correction means and outputting the first drive signal;
An image display unit for displaying a first image given by the input three primary color signals based on the first drive signal;
The second light emission characteristic is the same as the first light emission characteristic of the image display unit, and the second time change characteristic is the same as the first time change characteristic of the image display unit, and the second image is displayed in the normal operation period. On the other hand, a measurement display unit that displays the third image in the correction period;
Averaging processing for one screen is performed on each of the three primary color signals to be corrected by the gamma correction unit to generate an average three primary color signal that gives an average brightness of each of the three input primary color signals. Average brightness calculating means for outputting the averaged three primary color signals;
A test pattern generating means for holding at least one primary color test pattern signal for giving one screen for measurement and outputting the three primary color test pattern signal;
A first connection for outputting the averaged three primary color signals output from the average brightness calculation means according to the level of the first control signal, or the three primary color test output from the test pattern generation means. Switching means for switching between the second connection for outputting the pattern signal;
A measurement display unit driving means for generating a second driving signal for the three primary colors based on the output signal of the switching means and outputting the second driving signal;
In the normal operation period, the switching means has a first level for instructing the first connection, and in the correction period, the switching means has a second level for instructing the second connection. A switching means controller that generates and outputs a first control signal;
Detecting the brightness of the three primary colors of the third image, which is a basic pattern for measurement, which is disposed opposite to the display surface of the measurement display unit and displayed by the measurement display unit in the correction period; An optical sensor for outputting a detected primary color brightness signal;
The measurement display unit driving means has level data of the second driving signal generated from the three primary color test pattern signals, and at least based on the level data and the detected three primary color brightness signals A gamma correction control unit that generates conversion table data corresponding to the correction amount of the first drive signal necessary for correcting the white balance of the first image, and outputs the conversion table data as a second control signal. ,
The gamma correction means is a color display device that performs the gamma correction based on the conversion table data given by the second control signal,
A timer for measuring the elapsed time from a predetermined time point;
The correction period includes at least a preceding first correction period and a second correction period later than the first correction period,
The gamma correction control unit
At least a first correction coefficient and a second correction coefficient for the first elapsed time corresponding to the start of the first correction period, and a first correction coefficient and a second correction coefficient for the second elapsed time corresponding to the start of the second correction period. gives a correction factor, and further comprising means for storing a correction coefficient table data determined-out based on the temporal variation characteristic of a measurement system including the measurement display unit,
(A) Every time the detected three primary color brightness signals obtained in each of the first and second correction periods are received, the three primary colors are related based on the level data and the detected three primary color brightness signals. Means for generating data giving an approximate curve indicating a relationship between the second drive signal and the brightness in the third image;
(B) Every time the approximate curve data corresponding to each of the first and second correction periods is generated, the brightness ratio of each of the three primary colors in the first image is required to be a predetermined ratio. Temporary conversion table data that gives the second and third levels of the first drive signal for the other two colors with respect to the first level of the first drive signal for the reference color of the three primary colors is used as the approximate curve data. Means for generating based on,
(C) According to the measurement result of the timer, the first and second correction coefficients for the first elapsed time and the first and second correction coefficients for the second elapsed time are the first and second correction coefficients, respectively. Means for reading from the correction coefficient table data at a second elapsed time;
(D) For each generation of the provisional conversion table data corresponding to each of the first and second correction periods, for the first level of the first drive signal, (1) for the reference color, The first level of the first drive signal itself is given as the first correction level of the first drive signal. (2) For one of the other two colors, a first limiting process using the first correction coefficient is performed. A first restriction level obtained by executing the second level of the first drive signal is provided as a second correction level of the first drive signal; and (3) for the other of the other two colors, Limit correction table data that provides a second limit level obtained by executing a second limit process using a second correction coefficient on the third level of the first drive signal as a third correction level of the first drive signal. Means for generating;
(E) means for determining the conversion table data based on the limit correction table data for each generation of the limit correction table data corresponding to each of the first and second correction periods;
(F) further comprising means for outputting the conversion table data as the second control signal each time the conversion table data corresponding to each of the first and second correction periods is generated.
Color display device.

Gamma correction means for performing gamma correction on the input three primary color signals and outputting the corrected three primary color signals after correction;
Image display unit driving means for generating a first drive signal for the three primary colors based on the corrected three primary color signals of the gamma correction means and outputting the first drive signal;
An image display unit for displaying a first image given by the input three primary color signals based on the first drive signal;
The second light emission characteristic is the same as the first light emission characteristic of the image display unit, and the second time change characteristic is the same as the first time change characteristic of the image display unit, and the second image is displayed in the normal operation period. On the other hand, a measurement display unit that displays the third image in the correction period;
Averaging processing for one screen is performed on each of the three primary color signals to be corrected by the gamma correction unit to generate an average three primary color signal that gives an average brightness of each of the three input primary color signals. Average brightness calculating means for outputting the averaged three primary color signals;
A test pattern generating means for holding at least one primary color test pattern signal for giving one screen for measurement and outputting the three primary color test pattern signal;
A first connection for outputting the averaged three primary color signals output from the average brightness calculation means according to the level of the first control signal, or the three primary color test output from the test pattern generation means. Switching means for switching between the second connection for outputting the pattern signal;
A measurement display unit driving means for generating a second driving signal for the three primary colors based on the output signal of the switching means and outputting the second driving signal;
In the normal operation period, the switching means has a first level for instructing the first connection, and in the correction period, the switching means has a second level for instructing the second connection. A switching means controller that generates and outputs a first control signal;
Detecting the brightness of the three primary colors of the third image, which is a basic pattern for measurement, which is disposed opposite to the display surface of the measurement display unit and displayed by the measurement display unit in the correction period; An optical sensor for outputting a detected primary color brightness signal;
The measurement display unit driving means has level data of the second driving signal generated from the three primary color test pattern signals, and at least based on the level data and the detected three primary color brightness signals A gamma correction control unit that generates conversion table data corresponding to the correction amount of the first drive signal necessary for correcting the white balance of the first image, and outputs the conversion table data as a second control signal. ,
The gamma correction means is a color display device that performs the gamma correction based on the conversion table data given by the second control signal,
A timer for measuring the elapsed time from a predetermined time point;
The correction period includes at least a preceding first correction period and a second correction period later than the first correction period,
The gamma correction control unit
A first correction coefficient and a second correction coefficient with respect to a first elapsed time corresponding to the start of the first correction period are given, and correction coefficient table data determined based on a time-dependent change characteristic of the measurement system including the measurement display unit is stored. And further has means for
(A) The second drive relating to the three primary colors based on the level data and the detected three primary color brightness signals in response to reception of the detected three primary color brightness signals obtained in the first correction period. Means for generating data giving an approximate curve indicating a relationship between the signal and the brightness in the third image;
(B) In accordance with the generation of the approximate curve data corresponding to the first correction period, the three primary colors necessary for setting the ratio of the brightness of each of the three primary colors in the first image to a predetermined ratio. Temporary conversion table data that gives the second and third levels of the first drive signal for the other two colors with respect to the first level of the first drive signal for the reference color is generated based on the approximate curve data Means,
(C) According to the measurement result of the timer, the first and second correction coefficients for the first elapsed time are read from the correction coefficient table data at the first elapsed time, and more than the first correction coefficient Means for generating a first preceding correction coefficient having a small value and a second preceding correction coefficient having a value smaller than the second correction coefficient;
(D-1) With respect to the first level of the first drive signal, (1) for the reference color, the first level of the first drive signal itself is used as the first correction level of the first drive signal. (2) For one of the other two colors, a first preceding restriction obtained by executing a first preceding restriction process using the first preceding correction coefficient on the second level of the first drive signal. Level is given as the second preceding correction level of the first driving signal, and (3) with respect to the other of the other two colors, a second preceding restriction process using the second preceding correction coefficient is applied to the first driving signal. Means for generating preceding restriction correction table data that gives a second preceding restriction level obtained by executing the third level of the signal as a third preceding correction level of the first drive signal;
(E-1) means for determining the preceding conversion table data based on the preceding restriction correction table data and outputting the preceding conversion table data as the second control signal;
(D-2) With respect to the first level of the first drive signal at the time after the output of the preceding conversion table data and before the arrival of the second correction period, (1) regarding the reference color Gives the first level of the first drive signal itself as the first correction level of the first drive signal. (2) For one of the other two colors, the first restriction using the first correction coefficient is used. A first limit level obtained by executing processing on the second level of the first drive signal is provided as a second correction level of the first drive signal, and (3) for the other of the other two colors A limit correction table that gives a second limit level obtained by executing a second limit process using the second correction coefficient on the third level of the first drive signal as a third correction level of the first drive signal. Means for generating data;
(E-2) further comprising means for determining the conversion table data based on the limit correction table data before the second correction period arrives and outputting the conversion table data as the second control signal. Features
Color display device.

Gamma correction means for performing gamma correction on the input three primary color signals and outputting the corrected three primary color signals after correction;
Image display unit driving means for generating a first drive signal for the three primary colors based on the corrected three primary color signals of the gamma correction means and outputting the first drive signal;
An image display unit for displaying a first image given by the input three primary color signals based on the first drive signal;
The second light emission characteristic is the same as the first light emission characteristic of the image display unit, and the second time change characteristic is the same as the first time change characteristic of the image display unit, and the second image is displayed in the normal operation period. On the other hand, a measurement display unit that displays the third image in the correction period;
Averaging processing for one screen is performed on each of the three primary color signals to be corrected by the gamma correction unit to generate an average three primary color signal that gives an average brightness of each of the three input primary color signals. Average brightness calculating means for outputting the averaged three primary color signals;
A test pattern generating means for holding at least one primary color test pattern signal for giving one screen for measurement and outputting the three primary color test pattern signal;
A first connection for outputting the averaged three primary color signals output from the average brightness calculation means according to the level of the first control signal, or the three primary color test output from the test pattern generation means. Switching means for switching between the second connection for outputting the pattern signal;
A measurement display unit driving means for generating a second driving signal for the three primary colors based on the output signal of the switching means and outputting the second driving signal;
In the normal operation period, the switching means has a first level for instructing the first connection, and in the correction period, the switching means has a second level for instructing the second connection. A switching means controller that generates and outputs a first control signal;
Detecting the brightness of the three primary colors of the third image, which is a basic pattern for measurement, which is disposed opposite to the display surface of the measurement display unit and displayed by the measurement display unit in the correction period; An optical sensor for outputting a detected primary color brightness signal;
The measurement display unit driving means has level data of the second driving signal generated from the three primary color test pattern signals, and at least based on the level data and the detected three primary color brightness signals A gamma correction control unit that generates conversion table data corresponding to the correction amount of the first drive signal necessary for correcting the white balance of the first image, and outputs the conversion table data as a second control signal. ,
The gamma correction means is a color display device that performs the gamma correction based on the conversion table data given by the second control signal,
The gamma correction control unit
Means for storing adjustment completion time table data that gives the brightness of each of the three primary colors for the first drive signal at the time when the adjustment of the white balance and luminance of the first image is completed;
Based on the adjustment completion table data, the level data, and the detected three primary color brightness signals, the white balance and the luminance of the first image in the correction period are respectively adjusted when the adjustment is completed. Means for generating the conversion table data so as to be equal to the white balance and the luminance of an image,
Color display device.

The color display device according to claim 5 ,
The gamma correction control unit
(A) Based on the level data and the detected three primary color brightness signals, means for generating data that gives an approximate curve indicating the relationship between the second drive signal and the brightness in the third image for the three primary colors When,
(B) The first of the three primary colors required to make the white balance and the luminance of the first image in the correction period equal to the white balance and the luminance of the first image at the completion of the adjustment. , Provisional conversion table data giving first, second and third correction levels for the first, second and third levels of the first drive signal for the second and third colors, the adjustment completion table data and Means for generating based on the approximate curve data;
(C) (1) The first color is defined by the first level and the first correction level of the first drive signal at the completion of the adjustment, and the first level at the completion of the adjustment and the first color A level within a range excluding the first correction level is given as a first limit correction level of the first drive signal with respect to the first level of the first drive signal. (2) For the second color, the adjustment A level defined by the second level and the second correction level of the first drive signal at the time of completion and within a range excluding the second level and the second correction level at the time of completion of the adjustment is the first level. for the second level of the drive signal, applied as a second limit correction level of the first driving signal, and, (3) the respect to the third color, said first driving signal at the completion of adjustment A level within a range defined by three levels and the third correction level and excluding the third level and the third correction level when the adjustment is completed, with respect to the third level of the first drive signal. Means for generating limit correction table data to be given as a third limit correction level of one drive signal;
(D) further comprising means for determining the conversion table data based on the limit correction table data.
Color display device.

The color display device according to claim 5 ,
A timer for measuring the elapsed time from a predetermined time point;
The gamma correction control unit
A correction determined based on a time-dependent change characteristic of a measurement system including the measurement display unit by providing first, second, and third correction coefficients for the first, second, and third colors of the three primary colors with respect to the elapsed time. Means for storing coefficient table data;
(A) Based on the level data and the detected three primary color brightness signals, means for generating data that gives an approximate curve indicating the relationship between the second drive signal and the brightness in the third image for the three primary colors When,
(B) The first of the three primary colors, which is necessary to make the white balance and the luminance of the first image in the correction period equal to the white balance and the luminance of the first image at the completion of the adjustment. Temporary conversion table data that provides first, second, and third correction levels for the first, second, and third levels of the first drive signal for the first, second, and third colors is the adjustment completion table data. And means for generating based on the approximate curve data;
(C) The current elapsed time corresponding to the start of the correction period is obtained according to the measurement result of the timer, and the values of the first, second, and third correction coefficients at the current elapsed time are calculated as the correction coefficient table data. More reading means,
(D) (1) For the first color, a first restriction level obtained by executing a first restriction process using the first correction coefficient on the first level of the first drive signal is set to the first color. The first limit correction level of the first drive signal with respect to the first level of one drive signal is given. (2) For the second color, a second limit process using the second correction coefficient is applied to the first limit. A second limit level obtained by executing the second level of the drive signal as a second limit correction level of the first drive signal with respect to the second level of the first drive signal; and (3) For the third color, a third limit level obtained by executing a third limit process using the third correction coefficient on the third level of the first drive signal is set to the third limit level of the first drive signal. 3rd limit compensation of the first drive signal for 3 levels Means for generating a limit correction table data provided as level,
(E) further comprising means for determining the conversion table data based on the limit correction table data.
Color display device.

The color display device according to claim 5 ,
A timer for measuring the elapsed time from a predetermined time point;
The correction period includes at least a preceding first correction period and a second correction period later than the first correction period,
The gamma correction control unit
At least a first correction coefficient, a second correction coefficient, and a third correction coefficient for a first elapsed time corresponding to the start of the first correction period, and a first for a second elapsed time corresponding to the start of the second correction period. A correction coefficient table, a second correction coefficient, and a third correction coefficient, and a means for storing correction coefficient table data determined based on a time-dependent change characteristic of the measurement system including the measurement display unit.
(A) Every time the detected three primary color brightness signals obtained in each of the first and second correction periods are received, the three primary colors are related based on the level data and the detected three primary color brightness signals. Means for generating data giving an approximate curve indicating a relationship between the second drive signal and the brightness in the third image;
(B) for each generation of the approximate curve data corresponding to each of the first and second correction periods, the white balance of the first image in the correction period of the first and second correction periods, and The first of the first drive signals relating to the first, second and third colors of the three primary colors required to make the luminance equal to the white balance and the luminance of the first image at the completion of the adjustment. Means for generating provisional conversion table data for providing first, second and third correction levels for the second and third levels based on the approximate curve data and the adjustment completion table data;
(C) according to the measurement result of the timer, the first, second and third correction coefficients for the first elapsed time, and the first, second and third correction coefficients for the second elapsed time, Means for reading from the correction coefficient table data at the first and second elapsed times respectively;
(D) Every time the provisional conversion table data corresponding to each of the first and second correction periods is generated, (1) For the first color, a first restriction process using the first correction coefficient is performed. the first limit level obtained by executing the first level of the first driving signal, for said first level of said first drive signal, applied as a first limit correction level of the first drive signal, (2 ) For the second color, a second restriction level obtained by executing a second restriction process using the second correction coefficient on the second level of the first drive signal is set to the second drive level of the first drive signal. (3) With respect to the third color, a third restriction process using the third correction coefficient is applied to the second drive level as a second restriction correction level of the first drive signal. Third restriction obtained by executing to the third level Means for generating limit correction table data giving a level as a third limit correction level of the first drive signal with respect to the third level of the first drive signal;
(E) means for determining the conversion table data based on the limit correction table data for each generation of the limit correction table data corresponding to each of the first and second correction periods;
(F) further comprising means for outputting the conversion table data as the second control signal each time the conversion table data corresponding to each of the first and second correction periods is generated.
Color display device.

The color display device according to claim 5 ,
A timer for measuring the elapsed time from a predetermined time point;
The correction period includes at least a preceding first correction period and a second correction period later than the first correction period,
The gamma correction control unit
A first correction coefficient, a second correction coefficient, and a third correction coefficient for the first elapsed time corresponding to the start of the first correction period are provided, and the correction is determined based on the time-dependent change characteristics of the measurement system including the measurement display unit Means for storing coefficient table data;
(A) The second drive relating to the three primary colors based on the level data and the detected three primary color brightness signals in response to reception of the detected three primary color brightness signals obtained in the first correction period. Means for generating data giving an approximate curve indicating a relationship between a signal and brightness in the third image;
(B) In response to the generation of the approximate curve data corresponding to the first correction period, the white balance and the brightness of the first image in the first correction period are set to the first image at the completion of the adjustment. First and second for the first, second and third levels of the first drive signal for the first, second and third colors of the three primary colors required to equal the white balance and the luminance. And provisional conversion table data for giving a third correction level based on the adjustment completion table data and the approximate curve data;
(C) According to the measurement result of the timer, the first and second correction coefficients for the first elapsed time are read from the correction coefficient table data at the first elapsed time, and the first correction coefficient A first preceding correction coefficient having a smaller value, a second preceding correction coefficient having a smaller value than the second correction coefficient, and a third preceding correction coefficient having a smaller value than the third correction coefficient. Means for generating;
(D-1) (1) For the first color, a first preceding restriction obtained by executing a first preceding restriction process using the first preceding correction coefficient at the first level of the first drive signal. Level is given as a first advance limit correction level of the first drive signal with respect to the first level of the first drive signal. (2) For the second color, the second advance correction coefficient is used. A second preceding restriction level of the first driving signal with respect to the second level of the first driving signal is obtained by executing a second preceding restriction process on the second level of the first driving signal. (3) For the third color, a third preceding restriction process using the third preceding correction coefficient is performed on the third level of the first drive signal. The advance limit level is set to the first drive signal For 3 levels, means for generating a preceding limit correction table data to provide a third prior restrictions correction level of the first drive signal,
(E-1) means for determining the preceding conversion table data based on the preceding restriction correction table data and outputting the preceding conversion table data as the second control signal;
(D-2) At the time after the output of the preceding conversion table data and before the arrival of the second correction period, (1) For the first color, the first restriction using the first correction coefficient Providing a first limit level obtained by executing processing on the first level of the first drive signal as a first limit correction level of the first drive signal with respect to the first level of the first drive signal; (2) For the second color, a second restriction level obtained by executing a second restriction process using the second correction coefficient on the second level of the first drive signal is set to the first drive signal. And the second limit correction level of the first drive signal with respect to the second level, and (3) for the third color, a third limit process using the third correction coefficient is applied to the first drive. Obtained by running on the third level of the signal Means for generating restriction correction table data that gives a third restriction level as a third restriction correction level of the first drive signal with respect to the third level of the first drive signal;
(E-2) further comprising means for determining the conversion table data based on the limit correction table data before the second correction period arrives and outputting the conversion table data as the second control signal. Features
Color display device.