JP3585368B2 - Liquid crystal display device with image reading function, image reading method, and manufacturing method - Google Patents

Description

（ａ）上記画像表示時と同じ動作により、すべての画素に対応する部分の液晶層１４が透光状態にされる。
【００７５】
すなわち、ＴＦＴ制御回路３３にＴＦＴ（Ｌ） ２６の選択を指示するＴＦＴ選択信号が入力され、ＴＦＴ制御回路３３から、ゲート電圧Ｖｇ ＝ＶＬ （正）がゲートライン２３に出力されてＴＦＴ（Ｌ） ２６がオン状態になるとともに、Ｄ／Ａコンバータ３５ｂから、最大輝度に対応するソース電圧Ｖｓ ＝ＶｓＬｍａｘ がソースライン２２に出力され、透明画素電極２４と透明対向電極１５との間に電荷が蓄積されて、液晶層１４が透光状態になる。
【００７６】
（ｂ）上記画像表示時とはゲート電圧Ｖｇ およびソース電圧Ｖｓ が異なる動作によって、フォトダイオード２５に所定の電荷が蓄積される。
【００７７】
すなわち、ＴＦＴ制御回路３３にＴＦＴ（Ｄ） ２７の選択を指示するＴＦＴ選択信号が入力され、ＴＦＴ制御回路３３から、ゲート電圧Ｖｇ ＝ＶＤ （負）がゲートライン２３に出力されてＴＦＴ（Ｄ） ２７がオン状態になるとともに、表示画像データとして、フォトダイオード２５に印加する所定のソース電圧Ｖｓ ＝ＶｓＤ
に対応したデータがラインメモリ３５ａに入力されて、Ｄ／Ａコンバータ３５ｂから、上記所定のソース電圧Ｖｓ ＝ＶｓＤ がソースライン２２に出力される。そこで、フォトダイオード２５は逆バイアスが印加された状態となり、所定の電荷が蓄積される。
【００７８】
また、バックライト１８は、少なくともこの時点までに消灯される。
【００７９】
（ｃ）次に、バックライト１８が所定時間点灯されると、バックライト１８から発せられた光が液晶層１４を介して原稿に照射され、その反射光によってフォトダイオード２５が露光される。
【００８０】
そこで、フォトダイオード２５には、入射された光量に応じて、蓄積された電荷を相殺する電荷が発生し、蓄積電荷量が減少する。すなわち原稿画像の明度が高い（濃度が薄い）部分ほど、蓄積電荷量が多く減少する一方、明度が低い（濃度が濃い）部分では、蓄積電荷量はあまり減少しない。
【００８１】
（ｄ）バックライト１８が消灯された後、上記（ｂ）と同様に、ＴＦＴ制御回路３３からゲートライン２３にゲート電圧Ｖｇ ＝ＶＤ （負）が出力されて、ＴＦＴ（Ｄ） ２７がオン状態になる。なお、このときには、充電電圧出力回路３５のＤ／Ａコンバータ３５ｂの出力はハイインピーダンス状態に保たれる。
【００８２】
そこで、Ａ／Ｄコンバータ３６ａは、フォトダイオード２５の蓄積電荷の減少量に応じた読み取り画像データをラインメモリ３６ｂに出力し、ラインメモリ３６ｂは、１水平走査ライン分の各画素ごとの読み取り画像データを一旦保持し、シフトレジスタ３４からのタイミング信号に応じて、順次上記読み取り画像データを出力する。
【００８３】
なお、上記の例では、液晶層１４として誘電異方性が負のものを用いるとともに、偏光フィルタ層１１と偏光フィルタ層１７とを、一方の偏光フィルタ層の偏光方向と液晶の配向方向とが互いに平行で、かつ、両偏光フィルタ層１１・１７の偏光方向が互いに直交する方向（クロスニコル）に配置することにより、電界が作用したときに液晶層１４が透光状態になる例を示したが、誘電異方性が正の液晶を用いるとともに、偏光フィルタ層１１と偏光フィルタ層１７とを、液晶の配向方向、および両偏光フィルタ層１１・１７の偏光方向が互いに平行な方向（パラニコル）になるように配置しても同様である。
【００８４】
このように電界が作用したときに液晶層１４が透光状態になるように構成する場合には、透明画素電極２４およびフォトダイオード２５に印加する電圧ＶｓＬｍａｘ とＶＤ とを等しく設定することもでき、特に、これらのソース電圧Ｖｓ をＤ／Ａコンバータ３５ｂによらずに所定の電圧源から直接供給する場合などには、電圧源の種類を減らして回路の簡素化が容易になるなどの利点がある。
【００８５】
一方、誘電異方性が負の９０°のツイストネマティック液晶を用いるとともに、偏光フィルタ層１１と偏光フィルタ層１７とを、偏光方向が平行な方向（パラニコル）になるように配置するか、または、誘電異方性が正の液晶を用いるとともに、偏光フィルタ層１１と偏光フィルタ層１７とを、偏光方向が直交する方向（クロスニコル）に配置するようにしてもよい。すなわち、この場合には、液晶層１４は、電界が作用していないときに透光状態になるので、上記ソース電圧Ｖｓ ＝ＶｓＬｍａｘ に代えてＶｓ ＝ＶｓＬｍｉｎ を印加し、透明画素電極２４と透明対向電極１５との間に蓄積されている電荷を放電させるようにすればよい。
【００８６】
また、バックライト１８は露光時以外には消灯する例を示したが、点灯状態でもフォトダイオード２５に電荷を十分蓄積させ得る場合には、点灯したままにするようにしてもよい。ただし、この場合には、各ＴＦＴ（Ｄ） ２７がオフ状態になりしだい放電が始まるので、それぞれオフ状態になった時点から等しいディレイタイムで、読み出しを行うか、または一旦液晶層１４を遮光状態にするなどして、各フォトダイオード２５の露光時間が同じになるようにする必要があるが、バックライト１８を点灯、消灯させる場合に比べて、露光時間の正確な制御が容易になる。
【００８７】
さらに、下記表２に示すように、フォトダイオード２５に電荷を蓄積させた後に、液晶層１４を透光状態にするようにしてもよい。また、この場合にも、液晶層１４の遮光効果が十分であれば、バックライト１８を点灯したままにしてもよい。ただし、その場合には、上記の場合のように各フォトダイオード２５の露光時間が同じになるようにする必要がある。一方、バックライト１８を消灯した状態でフォトダイオード２５に電荷を蓄積する場合において、載置された原稿の背面から透過する光の影響があまりない場合には、同表に示すようにフォトダイオード２５に電荷を蓄積する際に液晶層１４を遮光状態にしておく必要は必ずしもない。
【表２】

【００８８】
また、上記の例では、全画素を対象として、１サイクルのフォトダイオード２５等への電荷の蓄積、フォトダイオード２５の露光、画像データの出力の動作を行わせることにより、画像データの読み取りを行う例を示したが、各画素ごとに上記サイクルの動作を繰り返すことにより画像データを読み取るようにしてもよい。すなわち、前者の場合には、上記１サイクルの動作によって画像データの読み取りが行われるので、速い読み取り速度が得られるのに対し、後者の場合には、各画素ごとにバックライト１８からの光が原稿に照射されるので、原稿における周辺の画素からの反射光がフォトダイオード２５に入射することによるクロストークが防止され、したがって、高い解像度が容易に得られる。また、１本のソースライン２２（またはゲートライン２３）に添った１ライン分の画素ごとに、上記サイクルの動作を繰り返すことにより、画像データを読み取るようにしてもよい。この場合には、上記ソースライン２２（またはゲートライン２３）に垂直な方向のクロストークが防止されるので、解像度をある程度高くするとともに、読み取り速度も比較的速くすることができる。さらに、複数個おきの画素や、１ラインおきの画素ごとに上記サイクルの動作を繰り返すことによっても、高解像度化および読み取り速度の高速化を図ることができる。
【００８９】
また、上記各構成材料や、製造プロセスにおける各工程の順序、プロセス条件等は、一例であり、これらに限定するものではない。
【００９０】
（実施の形態２）
画像読み取り機能付き液晶表示装置を構成するアクティブマトリクスパネル１３の他の例として、遮光電極２８上にＴＦＴ（Ｌ） ２６およびＴＦＴ（Ｄ） ２７が形成されるとともに、半導体層２６ｄ・２７ｄの上方にゲート電極２６ｂ・２７ｂが設けられたスタガ型のＴＦＴが用いられる例を説明する。なお、以下、前記実施の形態１と同一の機能を有する構成要素については、同一の番号を付して詳細な説明を省略する。
【００９１】
ガラス基板１２上には、図６および図７に示すように、遮光電極２８が形成され、その上に、例えばＳｉＯ_２ から成る絶縁膜２９を介して、ＴＦＴ（Ｌ） ２６またはＴＦＴ（Ｄ） ２７の半導体層２６ｄ・２７ｄが形成されている。なお、フォトダイオード２５の半導体層２５ａは、実施の形態１と同様に遮光電極２８上に直接形成され、遮光電極２８がアノード側の配線パターンを構成するようになっている。
【００９２】
半導体層２６ｄ・２７ｄの上方には、オーミック層２６ｅ・２７ｅ、ソース電極２６ａ・２７ａ、およびドレイン電極２６ｃ・２７ｃが形成され、さらに、ゲート絶縁膜４３を介して、ゲート電極２６ｂ・２７ｂが形成されている。
【００９３】
このように遮光電極２８によってフォトダイオード２５の配線パターンを構成することにより、通常の液晶表示装置と同じ工程で画像読み取り機能を備えた液晶表示装置を製造することができるので、製造コストの低減を容易に図ることができる。
【００９４】
（実施の形態３）
ＴＦＴ（Ｌ） ２６、およびＴＦＴ（Ｄ） ２７がともにｎチャネルのＴＦＴに形成され、ＴＦＴ（Ｌ） ２６のゲートの閾値電圧ＶＬ０がＴＦＴ（Ｄ） ２７のゲートの閾値電圧ＶＤ０よりも高く設定されている例を説明する。
【００９５】
すなわち、ＶＤ０＜Ｖｇ ＜ＶＬ０であるゲート電圧Ｖｇ がゲートライン２３に印加された場合には、ＴＦＴ（Ｄ） ２７だけがオン状態になる一方、ＶＬ０＜Ｖｇ であるゲート電圧Ｖｇ が印加された場合には、ＴＦＴ（Ｌ） ２６、およびＴＦＴ（Ｄ） ２７がともにオン状態になるようになっている。このような閾値電圧の設定は、半導体層２６ｄ・２７ｄにリン等の不純物を注入する際に、その濃度を調節するなど、公知の種々の方法により行うことができる。
【００９６】
上記のようなＴＦＴ（Ｌ） ２６およびＴＦＴ（Ｄ） ２７を備えた画像読み取り機能付き液晶表示装置は、下記表３および以下に示すようにして原稿画像の読み取りが行われる。
【表３】

（ａ）ＶＬ０＜Ｖｇ であるゲート電圧Ｖｇ がゲートライン２３に出力されると、ＴＦＴ（Ｌ） ２６がオン状態になり、その時にソースライン２２に出力されているソース電圧Ｖｓ ＝ＶｓＬｍａｘ によって、透明画素電極２４と透明対向電極１５との間に電荷が蓄積され、すべての画素に対応する部分の液晶層１４が透光状態にされる。
【００９７】
また、その際にはＴＦＴ（Ｄ） ２７もオン状態になり、フォトダイオード２５にも同様にソース電圧Ｖｓ ＝ＶｓＬｍａｘ によって電荷が蓄積されるので、ＶｓＬｍａｘ ＝ＶｓＤに設定する場合には、次のフォトダイオード２５だけに電荷を蓄積するステップを省略することができる。
【００９８】
（ｂ）ＶＤ０＜Ｖｇ ＜ＶＬ０であるゲート電圧Ｖｇ がゲートライン２３に出力されると、ＴＦＴ（Ｄ） ２７だけがオン状態になるので、上記ソース電圧Ｖｓ ＝ＶｓＬｍａｘ とは異なる電圧ＶｓＤにより所定の電荷の蓄積が行われる。
【００９９】
また、バックライト１８は、少なくともこの時点までに消灯される。
【０１００】
（ｃ）次に、Ｖｇ ＜ＶＤ０であるゲート電圧Ｖｇ がゲートライン２３に出力され、ＴＦＴ（Ｌ） ２６およびＴＦＴ（Ｄ） ２７が何れもオフ状態になるとともに、バックライト１８が所定時間点灯されると、バックライト１８から発せられた光が液晶層１４を介して原稿に照射され、反射光によってフォトダイオード２５が露光され、フォトダイオード２５は原稿画像の濃度に応じた蓄積電荷量になる。
【０１０１】
（ｄ）バックライト１８が消灯された後、上記（ｂ）と同様に、ＶＤ０＜Ｖｇ ＜ＶＬ０であるゲート電圧Ｖｇ がゲートライン２３に出力され、ＴＦＴ（Ｄ） ２７だけがオン状態になって、読み取り画像データが得られる。
【０１０２】
なお、この実施の形態３においても、前記実施の形態１で説明したように、電荷の蓄積時と同じタイミングで画像データの読み出しを行うことにより各フォトダイオード２５の露光時間が同じになるようにして、バックライト１８を点灯したままにするようにしてもよい。
【０１０３】
また、実施の形態３のような構成では、画像の表示時、すなわちＴＦＴ（Ｌ） ２６をオン状態にする際には、必ずＴＦＴ（Ｄ） ２７もオン状態になるが、通常、フォトダイオード２５のアノード側の電位を接地電位にしておけば、フォトダイオード２５には逆バイアスの電圧が印加されるだけで、ほとんど電流が流れないので、表示画像に対する影響はほとんどない。
【０１０４】
このようにフォトダイオード２５に逆バイアスの電圧が印加されるようにすれば、画像の表示時にフリッカレスにして画質の向上を図るために、ソース電圧Ｖｓ の極性を１水平走査期間ごとに反転させたり、互いに隣り合うソースライン２２ごとに反転させる公知の手法を適用することも可能である。すなわち、この場合には、各画素のフォトダイオード２５ごとに、印加されるソース電圧Ｖｓ に応じて逆バイアスになるように接続したり、図８に示すように、ソース電圧Ｖｓ が正負何れの場合でも逆バイアスになるようにフォトダイオード２５を接続したりすればよい。
【０１０５】
なお、フォトダイオード２５のアノード側に負の電圧を印加することにより、表示の応答速度の向上に寄与させることも可能である。
【０１０６】
また、図９に示すように、切り換えスイッチ５１を設けて、画像の表示時にはフォトダイオード２５のアノード側にソース電圧Ｖｓ を印加するようにすれば、理論的にも表示画像に対する影響を皆無にすることができる。なお、この場合、フォトダイオード２５のアノード側に接続される配線を各ソースライン２２ごとに独立して設けるか、または、すべてのアノード側の配線を共通にする場合には、充電電圧出力回路３５からは各ソースライン２２に順次択一的にソース電圧Ｖｓ を印加する一方、他のソースライン２２はハイインピーダンス状態になるようにすればよい。
【０１０７】
また、上記各実施の形態では、透明対向電極１５が対向ガラス基板１６に形成されている例を示したが、これに限らず、例えば図１０に模式的に示すように、同一の基板上に透明画素電極２４と透明対向電極１５とが設けられる、いわゆる面内スイッチング方式（ＩＰＳ）の液晶表示装置にも同様に適用することができる。この場合、上記透明対向電極１５をフォトダイオード２５のアノード側の配線として用いるようにしてもよい。
【０１０８】
また、画像の読み取り時における透明画素電極２４と透明対向電極１５との間や、フォトダイオード２５への電荷の蓄積は、通常の画像表示時と異なり、全画素に同一の電圧を印加して行うので、すべてのゲートライン２３に同時に駆動パルスを出力して電荷を蓄積させるようにしてもよい。
【０１０９】
また、受光素子としては、フォトダイオード２５に限らず、電荷蓄積型の種々の受光素子が適用可能である。さらに、電荷蓄積型以外のフォトセンサを用いても、同様に原稿画像を読み取ることはできる。この場合には、露光に先立って電荷を蓄積するステップは不要であるとともに、Ａ／Ｄコンバータ３６ａとして、受光素子の両端の電圧を検出するものや、受光素子に流れる電流を検出するものなどを用いることができる。
【０１１０】
また、画像の表示、および読み取りは、それぞれ画面の全面にわたって行うものに限らず、表示領域と読み取り領域とに分けて、画像の表示と読み取りとを同時に行い得るようにしてもよい。すなわち、前述のようにバックライト１８を常時点灯させ得るように構成する場合や、バックライト１８の消灯時間が短く設定される場合などには、各領域ごとに、前記画像表示動作、または画像読み取り動作を行わせることにより、画像の表示と読み取りとを行わせることができる。さらに、上記画像の読み取り領域は、あらかじめ設定してもよいし、タッチパネルユニット１９によって原稿の載置が検出された領域を読み取り領域にするなどしてもよい。
【０１１１】
（実施の形態４）
カラー画像の表示、および読み取りができる液晶表示装置の例を説明する。
【０１１２】
この液晶表示装置は、図１１に示すように、対向ガラス基板１６と透明対向電極１５との間に、各透明画素電極２４に対応して赤、緑、または青の光を透過させる領域が形成されたマイクロカラーフィルタ６１を備えている。その他の構成は、前記モノクロームの液晶表示装置（実施の形態１、実施の形態２、または実施の形態３）と同様である。
【０１１３】
このように構成されることによって、前記モノクロームの液晶表示装置と同じ動作により、カラー画像の表示、および読み取りが行われる。すなわち、表示画像データとして、それぞれ赤、青、または緑の画像データが入力されると、加法混色によりカラー画像が表示される。また、各透明画素電極２４ごとに、マイクロカラーフィルタ６１を介して、赤、青、または緑の光が原稿に照射され、原稿画像における各色の成分に応じた反射光量が検出されるので、カラーの画像データが読み取られる。
【０１１４】
このようなカラーの液晶表示装置を構成する場合でも、前記モノクロームの液晶表示装置と同様に、ＴＦＴ（Ｌ） ２６とＴＦＴ（Ｄ） ２７とが共通のソースライン２２およびゲートライン２３によって制御され、ＴＦＴ（Ｄ） ２７専用のゲートライン等を必要としないので、画像の有効表示面積を大きくして、高い視認性を得ることができる。
【０１１５】
なお、この液晶表示装置においては、各３つの透明画素電極２４を透過する光の加法混色によって、所定の色の１つの画素（カラー画素）が構成される。そこで、各透明画素電極２４に対応する画素（単体画素）の画素密度がモノクロームの液晶表示装置における画素密度と同じである場合（例えば透明画素電極２４の大きさが同じ場合）には、カラー画素の画素密度（実質的な表示および読み取りの画素密度）は、モノクロームの液晶表示装置における画素密度の１／３になる。
【０１１６】
（実施の形態５）
カラー画素の画素密度が単体画素の画素密度と等しい場合、すなわち、例えば透明画素電極２４の大きさがモノクロームの液晶表示装置と同じ場合であっても、モノクロームの液晶表示装置における画素密度と同じカラー画素の画素密度が得られる液晶表示装置の例を説明する。
【０１１７】
この液晶表示装置は、図１２に示すように、バックライト１８が、それぞれ赤、青、または緑の単色光を発する単色光源１８ａ〜１８ｃを備えて構成されている。これらの単色光源１８ａ〜１８ｃは、図示しない制御部によって、それぞれ独立して点灯、消灯が制御されるようになっている。その他の構成は、前記モノクロームの液晶表示装置と同様である。
【０１１８】
以下、画像表示時の動作、および画像読み取り時の動作について説明する。
【０１１９】
（１）画像表示時の動作
赤、青、および緑の単色光源１８ａ〜１８ｃが、順次選択的に点灯し、各点灯期間に、それぞれ赤、青、または緑の表示画像データに基づいて、前記モノクロームの画像表示装置と同じ表示動作が行われる。すなわち、各単体画素ごとに、時分割で赤、青、および緑の成分が表示され、視覚の残像効果によりカラー画像の表示が行われる。このように、単色光源１８ａ〜１８ｃによって時分割で各色の画像を表示することにより、１つの単体画素をカラー画素として作用させることができ、カラー画素の画素密度を単体画素の画素密度と等しくすることができる。
【０１２０】
（２）画像読み取り時の動作
赤、青、および緑の単色光源１８ａ〜１８ｃが順次用いられ、各単色光源１８ａ…ごとに、前記モノクロームの液晶表示装置と同じ読み取り動作が行われることにより、それぞれ原稿画像における各色の成分の画像データが読み取られる。より詳しくは、まず、赤の単色光源１８ａが用いられ、赤の光が全ての透明画素電極２４を介して原稿に照射されて、原稿画像における赤の成分に応じた反射光量が検出される。次に、青の単色光源１８ｂが用いられて、青の成分の画像が読み取られ、さらに緑の単色光源１８ｃが用いられて、緑の成分の画像が読み取られる。このように、単色光源１８ａ〜１８ｃについて前記読み取り動作が３回繰り返されることにより、カラーの画像データが読み取られる。このように、単色光源１８ａ〜１８ｃを順次用いることによって、各単体画素ごとに赤、青、および緑の成分の画像が読み取られるので、マイクロカラーフィルタを用いる場合に比べて、３倍の画素密度でカラー画像を読み取ることができる。
【０１２１】
なお、前記モノクロームの液晶表示装置と同様に、ＴＦＴ（Ｌ） ２６とＴＦＴ（Ｄ） ２７とが共通のソースライン２２およびゲートライン２３によって制御され、ＴＦＴ（Ｄ） ２７専用のゲートライン等を必要としないことにより、画像の有効表示面積を大きくして、高い視認性を得ることができるが、ＴＦＴ（Ｄ） ２７専用のゲートライン等を設ける場合でも、画素密度を高くする効果は同様に得られる。
【０１２２】
（実施の形態６）
マイクロカラーフィルタを備え、かつ、読み取り画素密度の高い液晶表示装置の例を説明する。
【０１２３】
この液晶表示装置は、図１３に示すように、対向ガラス基板１６と透明対向電極１５との間に、各透明画素電極２４に対応して赤、緑、または青の光を透過させてカラー画像の表示を行うための表示用領域６１ａと、全ての色の光を透過させて原稿を照明するための照明用領域６１ｂとが形成されたマイクロカラーフィルタ６１を備えている。
【０１２４】
また、透明対向電極１５は、上記マイクロカラーフィルタ６１の表示用領域６１ａまたは照明用領域６１ｂに対応する領域が、それぞれ互いに接続された表示用対向電極１５ａと照明用対向電極１５ｂとに分割されている。上記照明用対向電極１５ｂは、図示しない制御回路によって制御されるスイッチ６２により、表示用対向電極１５ａに接続されるか、またはハイインピーダンス状態になるようになっている。なお、必ずしも表示用対向電極１５ａに接続されなくても、所定の電位に保たれるようにしてもよい。
【０１２５】
一方、ガラス基板１２上に形成された透明画素電極２４は、図１４および図１５に示すように、前記モノクロームの液晶表示装置における透明画素電極２４と同様にＴＦＴ（Ｌ） ２６に接続された表示用画素電極２４ａと、ソースライン２２に接続された照明用画素電極２４ｂとに分割されている。
【０１２６】
さらに、バックライト１８は、前記実施の形態５と同様に、それぞれ赤、青、または緑の単色光を発する単色光源１８ａ〜１８ｃを備えて構成されている。
【０１２７】
その他の構成は、前記モノクロームの液晶表示装置と同様である。
【０１２８】
以下、画像表示時の動作、および画像読み取り時の動作について説明する。
【０１２９】
（１）画像表示時の動作
画像表示時には、赤、青、および緑の単色光源１８ａ〜１８ｃが同時に点灯され、白色光源として作用する。また、スイッチ６２は開いて照明用対向電極１５ｂがハイインピーダンス状態に保たれ、照明用画素電極２４ｂの電位、すなわちソースライン２２の電位に係らず、照明用対向電極１５ｂと照明用画素電極２４ｂとの間に電荷が蓄積されないようにされて、常にバックライト１８からの光が遮光されるように制御される。なお、液晶層１４に電圧が印加されていないときに光が透過状態になるノーマリホワイトの液晶表示装置を構成する場合には、照明用対向電極１５ｂをハイインピーダンス状態ではなく、絶対値が十分大きな所定の電圧が印加されるようにすればよい。
【０１３０】
この状態で、前記実施の形態４と同じ動作が行われることにより、カラー画像の表示が行われる。すなわち、画素における照明用画素電極２４ｂの部分に入射する光が常に遮光される点を除き、実施の形態４と同じ作用によって、各表示用画素電極２４ａ、液晶層１４、およびマイクロカラーフィルタ６１の表示用領域６１ａを透過する光の加法混色によりカラー画像が表示される。
【０１３１】
この液晶表示装置においては、画素における照明用画素電極２４ｂの部分が遮光状態になるために、開口率が若干低下するが、実施の形態５の液晶表示装置が時分割により表示が行われるのに対して、各単体画素は常に画像データに応じた発光状態になるので、フリッカを生じることなくフレーム周期を所望の長さに設定することができる。
【０１３２】
（２）画像読み取り時の動作
画像の読み取り時には、下記表４〜６に示すように、前記モノクロームの液晶表示装置の動作に比べて以下の点が異なる動作が行われる。ただし、原稿の照明に関しては、実施の形態５と同様に、赤、青、および緑の単色光源１８ａ〜１８ｃが順次用いられる。
【表４】

【表５】

【表６】

【０１３３】
すなわち、前記表１〜３において透明画素電極２４と透明対向電極１５との間に電荷が蓄積されるステップでは、ソース電圧Ｖｓ ＝ＶｓＬｍｉｎ がソースライン２２に出力され、表示用画素電極２４ａと表示用対向電極１５ａとの間の電荷が放電されて、画素における表示用画素電極２４ａの部分は遮光状態にされる。これにより、マイクロカラーフィルタ６１における表示用領域６１ａの赤、青、または緑の光だけを透過させる作用は、画像の読み取りには影響しなくなる。
【０１３４】
また、原稿からの反射光によってフォトダイオード２５が露光されるステップでは、照明用対向電極１５ｂがスイッチ６２を介して表示用対向電極１５ａに接続されるとともに、最大輝度に対応するソース電圧Ｖｓ ＝ＶｓＬｍａｘ が、ソースライン２２を介して照明用画素電極２４ｂに印加され、画素における照明用画素電極２４ｂの部分が透光状態になる。そこで、マイクロカラーフィルタ６１の照明用領域６１ｂは前記のように全ての色の光を透過させるようになっているので、赤、青、または緑の何れの単色光源１８ａ〜１８ｃから発せられた単色光も、そのまま原稿に照射される。それゆえ、前記実施の形態５と同様に、赤、青、および緑の単色光源１８ａ〜１８ｃが順次用いられ、各単色光源１８ａ…ごとに、前記モノクロームの液晶表示装置と同じ読み取り動作が行われることにより、それぞれ原稿画像における各色の成分の画像データが読み取られる。
【０１３５】
上記のように、画像の表示時には、マイクロカラーフィルタを用いた３つの単体画素の加法混色によりカラー画像を表示する一方、画像の読み取り時には、各単体画素ごとに、赤、青、および緑の単色光源１８ａ〜１８ｃを用いて各色の成分を読み取ることにより、表示時の３倍の画素密度で原稿画像を読み取ることができる。
【０１３６】
【発明の効果】
本発明は、以上説明したような形態で実施され、以下に記載されるような効果を奏する。
【０１３７】
すなわち、受光素子の一端側に接続される第２のトランジスタ用のソースラインやゲートラインを設けることなく、各画素電極に接続される第１のトランジスタと共通のソースライン、およびゲートラインによって、第２のトランジスタだけをオン状態にし、受光素子により検出された原稿画像を読み取ることができるので、画像の有効表示面積の減少による視認性の低下を招くことなく、装置の小型化や操作性の向上、および製造コストの低減を図ることができる。
【図面の簡単な説明】
【図１】実施の形態１の画像読み取り機能付き液晶表示装置の外観構成を示す斜視図である。
【図２】実施の形態１のアクティブマトリクスパネル１３の回路構成を示す説明図である。
【図３】実施の形態１のアクティブマトリクスパネル１３の具体的な構成を示す平面図である。
【図４】図３のＡ−Ａ矢視およびＢ−Ｂ矢視断面図である。
【図５】実施の形態１のアクティブマトリクスパネル１３の製造方法を示す説明図である。
【図６】実施の形態２のアクティブマトリクスパネル１３の具体的な構成を示す平面図である。
【図７】図６のＡ−Ａ矢視およびＢ−Ｂ矢視断面図である。
【図８】実施の形態３の画像読み取り機能付き液晶表示装置の変形例（フォトダイオード２５の他の接続例）を示す回路図である。
【図９】実施の形態３の画像読み取り機能付き液晶表示装置の他の変形例（フォトダイオード２５のアノード側にソース電圧を印加する例）を示す回路図である
【図１０】面内スイッチング方式の液晶表示装置を構成した場合の例を示す説明図である。
【図１１】実施の形態４の画像読み取り機能付き液晶表示装置の外観構成を示す斜視図である。
【図１２】実施の形態５の画像読み取り機能付き液晶表示装置の外観構成を示す斜視図である。
【図１３】実施の形態６の画像読み取り機能付き液晶表示装置の外観構成を示す斜視図である。
【図１４】実施の形態６のアクティブマトリクスパネル１３の具体的な構成を示す平面図である。
【図１５】図１４のＡ−Ａ矢視およびＢ−Ｂ矢視断面図である。
【符号の説明】
１１ 偏光フィルタ層
１２ ガラス基板
１３ アクティブマトリクスパネル
１４ 液晶層
１５ 透明対向電極
１５ａ 表示用対向電極
１５ｂ 照明用対向電極
１６ 対向ガラス基板
１７ 偏光フィルタ層
１８ バックライト
１８ａ 赤の単色光源
１８ｂ 青の単色光源
１８ｃ 緑の単色光源
１９ タッチパネルユニット
２１ 表示・読み取り部
２２ ソースライン
２３ ゲートライン
２４ 透明画素電極
２４ａ 表示用画素電極
２４ｂ 照明用画素電極
２５ フォトダイオード
２６ ＴＦＴ（Ｌ）
２７ ＴＦＴ（Ｄ）
２８ 遮光電極
３１ 駆動回路部
３２ シフトレジスタ
３３ ＴＦＴ制御回路
３４ シフトレジスタ
３５ 充電電圧出力回路
３５ａ ラインメモリ
３５ｂ Ｄ／Ａコンバータ
３６ 読み取り回路
３６ａ Ａ／Ｄコンバータ
３６ｂ ラインメモリ
６１ マイクロカラーフィルタ
６１ａ 表示用領域
６１ｂ 照明用領域
６２ スイッチ
７１ 制御部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device having an image reading function provided with an active matrix panel provided with a light receiving element such as a thin film transistor (TFT) and a photodiode, and a liquid crystal layer, and an image reading method using such a liquid crystal display device. And a method for manufacturing such a liquid crystal display device.
[0002]
[Prior art]
In recent years, in order to reduce the size of an image display device, a display device using a liquid crystal is often used. In particular, a liquid crystal display device including an active matrix panel having a TFT is compared with a simple matrix type liquid crystal display device. Since high image quality can be easily obtained, it has been actively studied.
[0003]
On the other hand, in order to reduce the size of a reading device for reading a document image or the like, the document is brought into close contact with a two-dimensionally arranged image sensor so that the image can be read without using a scanning mechanism of the document or the sensor unit. Things are known.
[0004]
Further, by combining the image display device and the reading device as described above to display an image and to obtain image data by reading a document image or the like, the overall device can be reduced in size and operability can be improved. Improvements have also been proposed.
[0005]
Specifically, as disclosed in Japanese Patent Application Laid-Open No. 4-282609, an image sensor is provided on the back side of a transparent substrate on which a TFT and a transparent pixel electrode are formed in a liquid crystal display device. It is configured by arranging the formed transparent substrate.
[0006]
In addition, a device capable of displaying and reading a color image includes a backlight light source of white light, and a micro color filter in which a region for transmitting red, green, or blue light is formed for each pixel, and a device for each color is provided. A color image is displayed by controlling the light transmittance, and a color image is read by detecting the amount of light of each color reflected from the document. That is, display of one pixel of a predetermined color (hereinafter, referred to as “color pixel”) by combining three pixels of red, green, and blue (hereinafter, each pixel is referred to as “single pixel”). And reading is performed.
[0007]
[Problems to be solved by the invention]
However, in a configuration in which the transparent substrate on which a TFT or the like is formed and the transparent substrate on which an image sensor is formed as described above are placed one on top of the other, the transmittance of backlight light and light reflected from a document is reduced, so that image quality is reduced. Visibility and reading characteristics are deteriorated.
[0008]
As means for preventing such a decrease in visibility or the like, for example, as disclosed in JP-A-5-145699, a device in which an image reading device is provided so as to be freely opened and closed has been proposed. However, there is a problem that the provision of the opening / closing mechanism causes the structure to be complicated and lowers the reliability, and also requires the opening / closing operation every time an image is read, which in turn causes a reduction in operability. Have.
[0009]
Although a specific configuration is not described in the above-mentioned Japanese Patent Application Laid-Open No. 4-282609, there is a description that a TFT or the like and an image sensor may be mounted on the same transparent substrate. In such a configuration, the wiring pattern for controlling the image sensor in addition to the wiring pattern for controlling the TFT for display needs to be formed on the same substrate, so that the effective display area of the image is reduced. This also leads to a decrease in visibility.
[0010]
In general, a read image often requires a higher pixel density than a display image.However, in the case of an apparatus that reads a color image with a micro color filter, as described above, red and green are used. , And blue, the image data of one color pixel can be obtained, so that a color image cannot be read at a high pixel density. Further, since only the light of the color transmitted through the micro color filter is used for display and illumination of the original, it is necessary to increase the light emission amount of the backlight light source in order to increase the light amount. Therefore, in addition to an increase in manufacturing cost due to the provision of the micro color filter, there is a problem that power consumption is increased.
[0011]
In view of the above, the present invention provides a liquid crystal display device with an image reading function that can reduce the size and operability of the device and reduce the manufacturing cost without reducing the visibility. It is an object of the present invention to provide an image reading method using a simple liquid crystal display device and a method for manufacturing such a liquid crystal display device.
[0012]
Further, it is another object of the present invention to provide a liquid crystal display device with an image reading function that can obtain a high read pixel density and can reduce the manufacturing cost and the power consumption, and an image reading method using such a liquid crystal display device. And
[0013]
[Means for Solving the Problems]
In the liquid crystal display device with an image reading function of the present invention, a second transistor for a light receiving element is connected to a source line and a gate line to which a first transistor for a pixel electrode is connected, and the first transistor The threshold value of the gate voltage and the threshold value of the gate voltage of the second transistor are set so that at least only the second transistor can be turned on.
[0014]
With this configuration, a source line common to the first transistor connected to each pixel electrode can be provided without providing a dedicated source line or gate line for the second transistor connected to one end of the light receiving element. Further, since only the second transistor is turned on by the gate line and the original image detected by the light receiving element can be read, the visibility can be reduced due to a reduction in the effective display area of the image, and the size of the device can be reduced. And improvement in operability and reduction in manufacturing cost.
[0015]
To enable only the second transistor to be turned on as described above, for example, an n-channel transistor is used as the first transistor, and a p-channel transistor is used as the second transistor. A polar transistor may be used. Thus, by switching the polarity of the voltage applied to the gate line, the first transistor and the second transistor can be independently turned on. In addition, in the case of such a configuration, the tolerance of the threshold of the gate voltage in the first transistor and the second transistor and the variation in the voltage applied to the gate line in the manufacturing are high, so that the manufacturing cost can be reduced. It will be easier.
[0016]
In addition, a charge storage type device is used as the light receiving element, a liquid crystal device that is in a light transmitting state when an electric field is applied is used, and the first transistor and the second transistor are simultaneously turned on. It may be configured so that
[0017]
In this case, the first transistor and the second transistor are turned on at the same time, the liquid crystal is made to be in a light-transmitting state, and the light-receiving element can hold electric charges prior to exposure. The control for reading can be simplified, and the manufacturing cost can be reduced.
[0018]
Here, in order to enable the first transistor and the second transistor to be simultaneously turned on, for example, as these transistors, n-channel transistors or p-channel transistors having the same polarity are used. In addition, the absolute value of the threshold value of the gate voltage of the second transistor may be lower than the absolute value of the threshold value of the gate voltage of the first transistor.
[0019]
That is, for example, when the threshold value of the first transistor is VL and the threshold value of the second transistor is VD, and both are n-channel transistors, if the voltage Vg applied to the gate line is VD <Vg <VL, Only two transistors can be turned on, while if VL <Vg, both transistors can be turned on.
[0020]
On the other hand, when an electric field is applied to the liquid crystal, a twisted nematic (TN) liquid crystal having a negative dielectric anisotropy of 90 ° is used to make the liquid crystal in a light transmitting state. The pair of polarizing plates provided on the sides are arranged such that the polarizing direction of one of the polarizing plates and the orientation direction of the liquid crystal are parallel to each other and the polarizing directions of both polarizing plates are orthogonal to each other, or What is necessary is to use a TN liquid crystal having a positive 90 ° and make the alignment direction of the liquid crystal and the polarization directions of both polarizing plates parallel to each other.
[0021]
In order to prevent the current flowing through the light receiving element from affecting the displayed image when the second transistor is turned on together with the first transistor when displaying an image, for example, a photodiode is used as the light receiving element. Is used, the photodiode may be connected so that a reverse bias voltage is applied when an image is displayed. Further, when the same voltage as that of the source line is applied to the other end line connected to the other end of the light receiving element when displaying an image, the effect on the display image is theoretically surely prevented. be able to.
[0022]
Furthermore, a conductive light-shielding film formed on the same substrate as the light-receiving element may be used as the other end-side line connected to the other end of the light-receiving element. When applying the in-plane switching method formed on the same substrate, the counter electrode may be used. With this configuration, it is not necessary to provide a new wiring pattern, so that the visibility can be prevented from lowering due to the reduction in the effective display area of the image, and the manufacturing cost can be reduced.
[0023]
In addition, by providing a touch sensor on the front side of the liquid crystal to detect the installation state of the original, it is possible to confirm that the original is placed, or automatically when the placement of the original is detected. Image reading can be started, or the size of a placed document can be detected so that image data corresponding to the size can be obtained.
[0024]
The image reading method of the present invention uses a liquid crystal display device with an image reading function as described above to make the liquid crystal transmissive and to expose a light receiving element holding a predetermined charge with light reflected from a document. Thereafter, the exposure amount of the light receiving element is detected by turning on only the second transistor.
[0025]
Thus, at the time of reading the document image, only the light receiving element is connected to the source line, so that the document image can be read without being affected by the charge held in the pixel electrode.
[0026]
Here, in the case where a liquid crystal display device with an image reading function capable of simultaneously turning on the first transistor and the second transistor is used, when the liquid crystal is made to be in the light-transmitting state, a predetermined amount of light is simultaneously applied to the light receiving element. By holding the charges, the image reading time can be shortened.
[0027]
Further, the method for manufacturing a liquid crystal display device with an image reading function of the present invention, when manufacturing the liquid crystal display device with an image reading function as described above, the other end line connected to the other end side of the light receiving element, The gate electrode is formed in a step of forming a gate electrode of at least one of the first transistor and the second transistor.
[0028]
Accordingly, a liquid crystal display device having an image reading function can be manufactured in the same process as a normal liquid crystal display device, so that manufacturing costs can be easily reduced.
[0029]
In addition, a color image can be displayed or read by providing a color filter in which a region for transmitting light of a predetermined color is formed corresponding to each pixel electrode.
[0030]
Furthermore, by providing a plurality of back light sources that emit light of different colors from each other, it is possible to irradiate the document with multiple colors of light for each pixel and detect the amount of reflected light. Images can be read.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
As the liquid crystal display device with an image reading function according to the first embodiment of the present invention, as shown in FIG. 1, an example of a liquid crystal display device installed and used so that a display surface of an image is substantially horizontal will be described.
[0032]
(1) Overall configuration of liquid crystal display device
This liquid crystal display device includes a polarizing filter layer 11, an active matrix panel 13 in which a transparent pixel electrode 24 and the like are formed on a glass substrate 12, which will be described in detail later, a liquid crystal layer 14, and a counter glass substrate 16 in which a transparent counter electrode 15 is formed. , And the polarization filter layer 17 are laminated. A backlight 18 is provided below the polarization filter layer 11, and a touch panel unit 19 is provided above the polarization filter layer 17.
[0033]
In addition, for example, when applied to an apparatus such as a personal computer that uses an image display surface inclined, an L-shaped, U-shaped, or linear cross-sectional shape is formed around the image display area. A document guide or the like may be provided. When reading an image, the document may be rotated so that the display surface is substantially horizontal as shown in FIG.
[0034]
The liquid crystal layer 14 is formed by enclosing a 90 ° twisted nematic liquid crystal in a predetermined gap provided between the active matrix panel 13 and the transparent counter electrode 15. As the liquid crystal, one having a negative dielectric anisotropy is used, and the polarization filter layer 11 and the polarization filter layer 17 are arranged such that the polarization direction of one of the polarization filter layers and the orientation direction of the liquid crystal are parallel to each other, and Since the polarization directions of the two polarization filter layers 11 and 17 are arranged in a direction (crossed Nicols) perpendicular to each other, the liquid crystal layer 14 (more specifically, the polarization filter layers 11 and 17 and the liquid crystal layer 14) is in a light-transmitting state.
[0035]
Although the transparent counter electrode 15 is set to a predetermined potential Vp, the potential Vp may be inverted every horizontal scanning period or each field period in order to reduce the driving voltage.
[0036]
Further, as the touch panel unit 19, various types such as a contact type and a capacitance type can be applied. The touch panel unit 19 is not necessarily provided. However, by providing the touch panel unit 19, it is possible to confirm that the original is placed, and the image is automatically displayed when the placement of the original is detected. , Or the size of a placed document can be detected so that image data corresponding to the size can be obtained.
[0037]
(2) Configuration of Circuit Formed on Active Matrix Panel 13
As shown in FIG. 2, the active matrix panel 13 includes a display / read unit 21, a drive circuit unit 31 disposed around the display / read unit 21, and a control unit 71 that controls operations of the drive circuit unit 31 and the backlight 18. Is provided. Note that the control unit 71 may be provided outside the active matrix panel 13.
[0038]
The display / read unit 21 is provided with a source line 22 and a gate line 23 in directions orthogonal to each other. The transparent pixel electrode 24, the photodiode 25, the TFT (L) 26 for the transparent pixel electrode 24, and the TFT (D) for the photodiode 25 correspond to each intersection of the source line 22 and the gate line 23. 27 are provided.
[0039]
Here, the TFT (L) 26 is formed on an n-channel TFT, while the TFT (D) 27 is formed on a p-channel TFT. That is, by applying a positive voltage VL or a negative voltage VD to the gate line 23, the gate lines 23 can be controlled to be independently turned on. The polarity of the TFT (L) 26 and the polarity of the TFT (D) 27 may be opposite to each other. However, in general, when the TFT (L) 26 connected to the transparent pixel electrode 24 has n channels, the display speed is increased. It will be easier.
[0040]
The source electrodes 26a and 27a of the TFTs (L) 26 and TFT (D) 27 are connected to the source line 22, and the gate electrodes 26b and 27b are connected to the gate line 23.
[0041]
The drain electrode 26c of the TFT (L) 26 is connected to the transparent pixel electrode 24, while the drain electrode 27c of the TFT (D) 27 is connected to the cathode side of the photodiode 25. The anode side of the photodiode 25 is grounded via the light-shielding electrode 28. That is, the photodiode 25 is connected so that a reverse bias is applied.
[0042]
In order to improve the display quality, a capacitance element or the like is provided in parallel with the transparent pixel electrode 24 and the transparent counter electrode 15, or a capacitance is provided between each transparent pixel electrode 24 and the gate line 23 of an adjacent pixel. You may have it.
[0043]
The drive circuit unit 31 includes a shift register 32, a TFT control circuit 33, a shift register 34, a charging voltage output circuit 35, and a reading circuit 36.
[0044]
The shift register 32 sequentially shifts the pulse of the vertical synchronizing signal Vsync input once every one vertical scanning period in synchronization with the horizontal synchronizing signal Hsync which is also a vertical clock, and outputs it to the TFT control circuit 33 as a timing signal. It has become.
[0045]
The TFT control circuit 33 generates a gate voltage Vg having a voltage of VL (positive) or VD (negative) according to the timing signal and a TFT selection signal instructing selection of the TFT (L) 26 or the TFT (D) 27. Are sequentially output to each gate line 23, and the TFT (L) 26 and the TFT (D) 27 for each horizontal scanning line are turned on.
[0046]
The shift register 34 sequentially shifts the pulse of the horizontal synchronizing signal Hsync input once every one horizontal scanning period in synchronization with the horizontal clock Hck, takes in the display image data of each pixel, and outputs the read image data. The timing signal is output to the charging voltage output circuit 35 and the reading circuit 36.
[0047]
The charging voltage output circuit 35 includes a line memory 35a and a D / A converter (digital-analog converter) 35b.
[0048]
The line memory 35a stores display image data for each pixel for one horizontal scanning line according to a timing signal from the shift register 34.
[0049]
The D / A converter 35b outputs a source voltage Vs (for example, 0 to 6V) corresponding to the display image data held in the line memory 35a to the source line 22, and outputs a signal between the transparent pixel electrode 24 and the transparent counter electrode 15. Alternatively, a predetermined charge is stored in the photodiode 25.
[0050]
On the other hand, the reading circuit 36 is provided with an A / D converter (analog-digital converter) 36a and a line memory 36b.
[0051]
The A / D converter 36a is connected to the source line 22, detects the amount of exposure of the photodiode 25 due to light reflected from the document, and outputs read image data for each pixel. More specifically, for example, the electric charge accumulated in the photodiode 25 by a predetermined voltage (for example, 5 to 6 V) previously output from the D / A converter 35b is discharged by the exposure of the reflected light from the original, and then the discharged electric charge is discharged. When replenishing the charge, the amount of charge required for replenishment is detected, and corresponding digital data is output. It is to be noted that the voltage at both ends of the photodiode 25 after the above-described discharge may be detected without being limited to detecting the amount of charge required for replenishing the charge.
[0052]
The line memory 36b temporarily holds the read image data for each pixel for one horizontal scanning line output from the A / D converter 36a, and sequentially outputs the read image data according to a timing signal from the shift register 34. .
[0053]
(3) Specific configuration and manufacturing method of active matrix panel 13
The active matrix panel 13 is configured by arranging a transparent pixel electrode 24, a photodiode 25, a TFT (L) 26, a TFT (D) 27, etc. on a glass substrate 12, as shown in FIGS. 3 and 4, for example. ing.
[0054]
The photodiode 25 includes semiconductor layers 25a and 25b.
[0055]
The TFT (L) 26 and the TFT (D) 27 include a source electrode 26a / 27a, a gate electrode 26b / 27b, a drain electrode 26c / 27c, a semiconductor layer 26d / 27d, an ohmic layer 26e / 27e, and a gate insulating film. 43. In FIG. 3, the gate insulating film 43 is omitted for convenience. The source electrodes 26a and 27a and the gate electrodes 26b and 27b are formed by convex portions formed on the source line 22 or the gate line 23, respectively.
[0056]
The active matrix panel 13 as described above is manufactured, for example, as shown in FIG.
[0057]
(A) A 100 nm chromium layer 41 is deposited on a glass substrate 12 by a sputtering method.
[0058]
(B) The chromium layer 41 is patterned by etching to form the gate electrodes 26b and 27b and the light shielding electrode 28. The gate electrodes 26b and 27b form a gate line 23 in a cross section (not shown). The light-shielding electrode 28 forms a wiring pattern on the anode side of the photodiode 25.
[0059]
(C) An ITO layer 42 as a transparent electrode having a thickness of 100 nm is deposited on the glass substrate 12 by a sputtering method.
[0060]
(D) The ITO layer 42 is patterned by etching to form the transparent pixel electrode 24.
[0061]
(E) SiN by plasma CVD _X (For example, Si ₃ N ₄ ) Or SiO ₂ After depositing a 400 nm gate insulating film 43 made of, for example, the portion above the light shielding electrode 28 and the portion of the transparent pixel electrode 24 above the contact portion 24a with the drain electrode 26c are removed.
[0062]
(F) An amorphous silicon (a-Si) layer having a thickness of 100 nm is deposited by a plasma CVD method, a polycrystalline silicon (p-Si) layer is formed by crystallization using an excimer laser, and then patterned by etching. The semiconductor layers 26d and 27d for the TFT (L) 26 and the TFT (D) 27 and the semiconductor layer 25a for the photodiode 25 are formed.
[0063]
The semiconductor layer 26d is formed into an n-channel by implanting impurities such as phosphorus by ion implantation or ion shower, while the semiconductor layer 27d and the semiconductor layer 25a are implanted into a p-channel by implanting impurities such as boron. Form. In this case, instead of selectively implanting the impurities, the n-channel semiconductor layer 26d and the p-channel semiconductor layer 27d and the semiconductor layer 25a may be separately formed twice.
[0064]
(G) Similarly to the semiconductor layers 26d, 50-nm ohmic layers 26e and 27e are formed on the source and drain regions in the semiconductor layers 26d and 27d. Further, n is formed on the semiconductor layer 25a. ⁺ Is formed by forming an ohmic layer 25b of p-Si.
[0065]
(H) After depositing a 700 nm aluminum layer by sputtering, patterning is performed by etching to form source electrodes 26a and 27a and drain electrodes 26c and 27c, thereby forming the TFT (L) 26 and the TFT (D) 27. .
[0066]
The source electrodes 26a and 27a constitute a source line 22 in a cross section (not shown). The drain electrode 26c of the TFT (L) 26 is connected to the contact portion 24a of the transparent pixel electrode 24, while the drain electrode 27c of the TFT (D) 27 is connected to the ohmic layer 25b of the photodiode 25.
[0067]
Finally, a passivation film 44 is formed above the source electrode 26a, the drain electrode 26c, the semiconductor layer 26d, and the like.
[0068]
In the above-described manufacturing method, the display / read section 21 has been mainly described. However, especially when the polycrystalline silicon process is used as described above, the transistors and wirings constituting the drive circuit section 31 are also the same. It can be easily made at the same time in the process. On the other hand, when an amorphous silicon process is used, the driver IC may be mounted directly on the glass substrate 12 or may be mounted using a flexible substrate to form the drive circuit unit 31.
[0069]
(4) Operation when displaying images
After the pulse of the horizontal synchronizing signal Hsync is input to the shift register 34 and then the display image data for each pixel is input to the line memory 35a in synchronization with the horizontal clock Hck, the line memory 35a stores data for one horizontal scanning line. The display image data is sequentially held, and the D / A converter 35b outputs a voltage corresponding to each display image data to each source line 22.
[0070]
After the pulse of the vertical synchronization signal Vsync is input to the shift register 32, the vertical clock Vck (horizontal synchronization signal Hsync) is input, and the TFT control circuit 33 is instructed to select the TFT (L) 26. When the TFT selection signal is input, the TFT control circuit 33 outputs a drive pulse of the voltage VL (positive) to the gate line 23 corresponding to the first horizontal scanning line.
[0071]
Then, each TFT (L) 26 connected to the gate line 23 is turned on, and the voltage between the transparent pixel electrode 24 and the transparent counter electrode 15 is changed according to the voltage output from the D / A converter 35b. The accumulated charges are accumulated to form an electric field. That is, the portion of the liquid crystal layer 14 corresponding to each transparent pixel electrode 24 rotates the plane of polarization of the light from the backlight 18 and enters a light-transmitting state with a luminance corresponding to each display image data. This state is maintained until a drive pulse is applied again to the same gate line 23 in the next field.
[0072]
As described above, the voltage corresponding to the display image data is not output to each source line 22 at the same time, but is output sequentially for each pixel in one horizontal scanning line in synchronization with the horizontal clock Hck or the like. Is also good.
[0073]
Hereinafter, the same operation is performed for each horizontal scanning line every time the horizontal synchronization signal Hsync is input, whereby an image for one screen is displayed.
[0074]
(5) Operation when reading an image
When an image reading switch (not shown) is operated in a state where the document is placed on the liquid crystal display device and the placement of the document is detected by the touch panel unit 19, the document image is read as shown in Table 1 below and below. Is performed.
[Table 1]

(A) By the same operation as that at the time of displaying an image, the liquid crystal layer 14 in a portion corresponding to all pixels is made to be in a light transmitting state.
[0075]
That is, a TFT selection signal instructing selection of the TFT (L) 26 is input to the TFT control circuit 33, and a gate voltage Vg = VL (positive) is output from the TFT control circuit 33 to the gate line 23 and the TFT (L) 26 is turned on, the source voltage Vs = VsLmax corresponding to the maximum luminance is output from the D / A converter 35b to the source line 22, and charges are accumulated between the transparent pixel electrode 24 and the transparent counter electrode 15. Thus, the liquid crystal layer 14 is in a light transmitting state.
[0076]
(B) A predetermined charge is accumulated in the photodiode 25 by an operation in which the gate voltage Vg and the source voltage Vs are different from those during the image display.
[0077]
That is, a TFT selection signal instructing selection of the TFT (D) 27 is input to the TFT control circuit 33, and a gate voltage Vg = VD (negative) is output from the TFT control circuit 33 to the gate line 23 and the TFT (D) 27 is turned on, and a predetermined source voltage Vs = VsD applied to the photodiode 25 as display image data.
Is input to the line memory 35a, and the predetermined source voltage Vs = VsD is output to the source line 22 from the D / A converter 35b. Therefore, the photodiode 25 is in a state where a reverse bias is applied, and a predetermined charge is accumulated.
[0078]
The backlight 18 is turned off at least up to this point.
[0079]
(C) Next, when the backlight 18 is turned on for a predetermined time, the light emitted from the backlight 18 is applied to the document via the liquid crystal layer 14, and the photodiode 25 is exposed by the reflected light.
[0080]
Therefore, in the photodiode 25, charges that cancel the accumulated charges are generated in accordance with the incident light amount, and the accumulated charge amount decreases. That is, the higher the brightness (lower density) of the document image, the more the stored charge decreases, while the lower the brightness (high density), the less the stored charge.
[0081]
(D) After the backlight 18 is turned off, the gate voltage Vg = VD (negative) is output from the TFT control circuit 33 to the gate line 23 as in (b) above, and the TFT (D) 27 is turned on. become. At this time, the output of the D / A converter 35b of the charging voltage output circuit 35 is kept in a high impedance state.
[0082]
Therefore, the A / D converter 36a outputs read image data corresponding to the amount of charge reduction of the photodiode 25 to the line memory 36b, and the line memory 36b reads the read image data for each pixel for one horizontal scanning line. Is temporarily held, and the read image data is sequentially output according to the timing signal from the shift register 34.
[0083]
In the above example, the liquid crystal layer 14 having a negative dielectric anisotropy is used, and the polarization filter layer 11 and the polarization filter layer 17 are arranged such that the polarization direction of one of the polarization filter layers and the alignment direction of the liquid crystal are different. The liquid crystal layer 14 is in a light-transmitting state when an electric field is applied by arranging the polarizing filter layers 11 and 17 in parallel (crossed Nicols) in which the polarization directions of the polarizing filter layers 11 and 17 are perpendicular to each other. However, while using a liquid crystal having a positive dielectric anisotropy, the polarization filter layer 11 and the polarization filter layer 17 are arranged so that the alignment direction of the liquid crystal and the polarization directions of the two polarization filter layers 11 and 17 are parallel to each other (paranicol). It is the same even if it arrange | positions so that it may become.
[0084]
When the liquid crystal layer 14 is configured to be in a light transmitting state when an electric field is applied in this manner, the voltages VsLmax and VD applied to the transparent pixel electrode 24 and the photodiode 25 can be set to be equal. In particular, when these source voltages Vs are directly supplied from a predetermined voltage source without using the D / A converter 35b, there is an advantage that the number of types of the voltage sources is reduced and the circuit is simplified easily. .
[0085]
On the other hand, a twisted nematic liquid crystal having a negative dielectric anisotropy of 90 ° is used, and the polarization filter layer 11 and the polarization filter layer 17 are arranged so that the polarization directions are parallel (paranicol). A liquid crystal having a positive dielectric anisotropy may be used, and the polarization filter layer 11 and the polarization filter layer 17 may be arranged in a direction in which the polarization directions are orthogonal (crossed Nicols). That is, in this case, the liquid crystal layer 14 is in a light-transmitting state when no electric field is applied. Therefore, Vs = VsLmin is applied instead of the source voltage Vs = VsLmax, and the liquid crystal layer 14 is transparently opposed to the transparent pixel electrode 24. What is necessary is just to discharge the electric charge accumulated between the electrodes 15.
[0086]
Also, an example has been described in which the backlight 18 is turned off except during exposure. However, even when the backlight 18 is turned on, if the photodiode 25 can sufficiently store charges, the backlight 18 may be kept turned on. However, in this case, discharge starts as soon as each TFT (D) 27 is turned off, so that reading is performed with the same delay time from the time when each TFT (D) 27 is turned off, or the liquid crystal layer 14 is temporarily shielded from light. For example, it is necessary to make the exposure times of the photodiodes 25 equal to each other, but accurate control of the exposure time becomes easier as compared with the case where the backlight 18 is turned on and off.
[0087]
Further, as shown in Table 2 below, the liquid crystal layer 14 may be made to be in a light transmitting state after the charge is accumulated in the photodiode 25. Also in this case, if the light blocking effect of the liquid crystal layer 14 is sufficient, the backlight 18 may be kept on. However, in that case, it is necessary to make the exposure time of each photodiode 25 the same as in the above case. On the other hand, in the case where electric charges are accumulated in the photodiode 25 with the backlight 18 turned off, if there is little influence of light transmitted from the back of the placed document, as shown in the table, It is not always necessary to keep the liquid crystal layer 14 in a light-shielding state when accumulating electric charges in the liquid crystal layer.
[Table 2]

[0088]
Further, in the above example, the image data is read by performing the operations of accumulating the charge in the photodiode 25 and the like, exposing the photodiode 25, and outputting the image data in one cycle for all the pixels. Although an example has been described, image data may be read by repeating the above-described operation for each pixel. That is, in the former case, the image data is read by the above-described one-cycle operation, so that a high reading speed can be obtained. In the latter case, the light from the backlight 18 is emitted for each pixel. Since the document is illuminated, crosstalk due to reflected light from peripheral pixels in the document being incident on the photodiode 25 is prevented, so that high resolution can be easily obtained. Further, the image data may be read by repeating the above-described operation for each pixel of one line along one source line 22 (or gate line 23). In this case, since crosstalk in the direction perpendicular to the source line 22 (or the gate line 23) is prevented, the resolution can be increased to some extent and the reading speed can be relatively increased. Further, by repeating the operation of the above-described cycle for every plural pixels or every other line, it is possible to increase the resolution and the reading speed.
[0089]
In addition, the above-described constituent materials, the order of each step in the manufacturing process, the process conditions, and the like are merely examples, and the present invention is not limited thereto.
[0090]
(Embodiment 2)
As another example of the active matrix panel 13 that constitutes the liquid crystal display device with an image reading function, a TFT (L) 26 and a TFT (D) 27 are formed on a light-shielding electrode 28, and above the semiconductor layers 26d and 27d. An example in which a staggered TFT provided with gate electrodes 26b and 27b is used will be described. In the following, components having the same functions as those of the first embodiment are denoted by the same reference numerals, and detailed description is omitted.
[0091]
As shown in FIGS. 6 and 7, a light-shielding electrode 28 is formed on the glass substrate 12. ₂ Semiconductor layers 26d and 27d of the TFT (L) 26 or the TFT (D) 27 are formed via an insulating film 29 made of. The semiconductor layer 25a of the photodiode 25 is formed directly on the light-shielding electrode 28 as in the first embodiment, and the light-shielding electrode 28 forms an anode-side wiring pattern.
[0092]
Above the semiconductor layers 26d and 27d, ohmic layers 26e and 27e, source electrodes 26a and 27a, and drain electrodes 26c and 27c are formed, and further, gate electrodes 26b and 27b are formed via a gate insulating film 43. ing.
[0093]
By configuring the wiring pattern of the photodiode 25 with the light-shielding electrodes 28 in this manner, a liquid crystal display device having an image reading function can be manufactured in the same process as a normal liquid crystal display device, so that manufacturing costs can be reduced. It can be easily achieved.
[0094]
(Embodiment 3)
The TFT (L) 26 and the TFT (D) 27 are both formed as n-channel TFTs, and the threshold voltage VL0 of the gate of the TFT (L) 26 is set higher than the threshold voltage VD0 of the gate of the TFT (D) 27. Will be described.
[0095]
That is, when the gate voltage Vg satisfying VD0 <Vg <VL0 is applied to the gate line 23, only the TFT (D) 27 is turned on, while the gate voltage Vg satisfying VL0 <Vg is applied. , Both the TFT (L) 26 and the TFT (D) 27 are turned on. Such a setting of the threshold voltage can be performed by various known methods such as adjusting the concentration when impurities such as phosphorus are implanted into the semiconductor layers 26d and 27d.
[0096]
The liquid crystal display device with the image reading function provided with the TFT (L) 26 and the TFT (D) 27 as described above reads a document image as shown in Table 3 and below.
[Table 3]

(A) When the gate voltage Vg satisfying VL0 <Vg is output to the gate line 23, the TFT (L) 26 is turned on, and the source voltage Vs = VsLmax output to the source line 22 at that time makes the TFT (L) transparent. Electric charges are accumulated between the pixel electrode 24 and the transparent counter electrode 15, and the liquid crystal layer 14 corresponding to all pixels is made to be in a light transmitting state.
[0097]
At this time, the TFT (D) 27 is also turned on, and electric charges are similarly stored in the photodiode 25 by the source voltage Vs = VsLmax. Therefore, when setting VsLmax = VsD, the next photo The step of accumulating charges only in the diode 25 can be omitted.
[0098]
(B) When the gate voltage Vg that satisfies VD0 <Vg <VL0 is output to the gate line 23, only the TFT (D) 27 is turned on, so that a predetermined voltage VsD different from the source voltage Vs = VsLmax is used. Charge accumulation is performed.
[0099]
The backlight 18 is turned off at least up to this point.
[0100]
(C) Next, the gate voltage Vg satisfying Vg <VD0 is output to the gate line 23, the TFT (L) 26 and the TFT (D) 27 are both turned off, and the backlight 18 is turned on for a predetermined time. Then, the light emitted from the backlight 18 is applied to the document via the liquid crystal layer 14, and the reflected light exposes the photodiode 25, and the photodiode 25 has an accumulated charge amount corresponding to the density of the document image.
[0101]
(D) After the backlight 18 is turned off, the gate voltage Vg satisfying VD0 <Vg <VL0 is output to the gate line 23, and only the TFT (D) 27 is turned on, as in (b) above. Thus, read image data is obtained.
[0102]
In the third embodiment as well, as described in the first embodiment, the image data is read out at the same timing as when the electric charges are accumulated, so that the exposure times of the photodiodes 25 become the same. Thus, the backlight 18 may be kept on.
[0103]
In the configuration as in the third embodiment, the TFT (D) 27 is always turned on when displaying an image, that is, when the TFT (L) 26 is turned on. If the potential on the anode side is set to the ground potential, only a reverse bias voltage is applied to the photodiode 25 and almost no current flows, so that there is almost no effect on the displayed image.
[0104]
When a reverse bias voltage is applied to the photodiode 25 in this manner, the polarity of the source voltage Vs is inverted every horizontal scanning period in order to improve image quality without flickering during image display. Alternatively, a known method of inverting the source lines 22 adjacent to each other may be applied. That is, in this case, each photodiode 25 of each pixel is connected so as to be reverse biased in accordance with the applied source voltage Vs, or when the source voltage Vs is either positive or negative as shown in FIG. However, the photodiode 25 may be connected so as to be reverse biased.
[0105]
Note that by applying a negative voltage to the anode side of the photodiode 25, it is possible to contribute to an improvement in the response speed of display.
[0106]
Further, as shown in FIG. 9, if a changeover switch 51 is provided so that the source voltage Vs is applied to the anode side of the photodiode 25 at the time of displaying an image, there is theoretically no influence on the displayed image. be able to. In this case, the wiring connected to the anode side of the photodiode 25 is provided independently for each source line 22, or the charge voltage output circuit 35 is used when all the wirings on the anode side are shared. After that, the source voltage Vs may be sequentially and selectively applied to each source line 22, while the other source lines 22 may be brought into a high impedance state.
[0107]
In each of the above embodiments, the example in which the transparent counter electrode 15 is formed on the counter glass substrate 16 has been described. However, the present invention is not limited to this. For example, as illustrated schematically in FIG. The present invention can be similarly applied to a so-called in-plane switching (IPS) liquid crystal display device in which the transparent pixel electrode 24 and the transparent counter electrode 15 are provided. In this case, the transparent counter electrode 15 may be used as a wiring on the anode side of the photodiode 25.
[0108]
In addition, unlike the normal image display, the same voltage is applied to all the pixels between the transparent pixel electrode 24 and the transparent counter electrode 15 and the charge accumulation in the photodiode 25 when reading an image. Therefore, a drive pulse may be simultaneously output to all the gate lines 23 to accumulate charges.
[0109]
The light receiving element is not limited to the photodiode 25, and various charge storage type light receiving elements can be applied. Further, even if a photosensor other than the charge accumulation type is used, the original image can be read similarly. In this case, the step of accumulating the electric charges prior to the exposure is unnecessary, and the A / D converter 36a may be a type that detects the voltage across the light receiving element, a type that detects the current flowing through the light receiving element, or the like. Can be used.
[0110]
Further, display and reading of an image are not limited to being performed over the entire screen, respectively, and display and reading of an image may be performed simultaneously in a display region and a reading region. That is, in the case where the backlight 18 is configured to be always lit as described above, or in the case where the turning-off time of the backlight 18 is set to be short, the image display operation or the image reading operation is performed for each region. By performing the operation, display and reading of an image can be performed. Further, the image reading area may be set in advance, or the area where the placement of the document is detected by the touch panel unit 19 may be set as the reading area.
[0111]
(Embodiment 4)
An example of a liquid crystal display device capable of displaying and reading a color image will be described.
[0112]
In this liquid crystal display device, as shown in FIG. 11, a region for transmitting red, green, or blue light corresponding to each transparent pixel electrode 24 is formed between the opposite glass substrate 16 and the transparent opposite electrode 15. The micro color filter 61 is provided. Other configurations are the same as those of the monochrome liquid crystal display device (Embodiment 1, Embodiment 2, or Embodiment 3).
[0113]
With this configuration, a color image is displayed and read by the same operation as that of the monochrome liquid crystal display device. That is, when red, blue, or green image data is input as display image data, a color image is displayed by additive color mixture. In addition, for each transparent pixel electrode 24, red, blue, or green light is emitted to the original via the micro color filter 61, and the amount of reflected light corresponding to each color component in the original image is detected. Is read.
[0114]
Even when such a color liquid crystal display device is configured, similarly to the monochrome liquid crystal display device, the TFT (L) 26 and the TFT (D) 27 are controlled by the common source line 22 and gate line 23, Since a gate line or the like dedicated to the TFT (D) 27 is not required, an effective display area of an image can be increased and high visibility can be obtained.
[0115]
In this liquid crystal display device, one pixel (color pixel) of a predetermined color is formed by additive color mixture of light transmitted through each of the three transparent pixel electrodes 24. Therefore, when the pixel density of the pixel (single pixel) corresponding to each transparent pixel electrode 24 is the same as the pixel density in the monochrome liquid crystal display device (for example, when the size of the transparent pixel electrode 24 is the same), the color pixel (Substantial display and reading pixel density) is 1/3 of the pixel density in a monochrome liquid crystal display device.
[0116]
(Embodiment 5)
When the pixel density of a color pixel is equal to the pixel density of a single pixel, that is, for example, even when the size of the transparent pixel electrode 24 is the same as that of a monochrome liquid crystal display, the same color as the pixel density in the monochrome liquid crystal display is used. An example of a liquid crystal display device that can obtain a pixel density of pixels will be described.
[0117]
In this liquid crystal display device, as shown in FIG. 12, the backlight 18 includes monochromatic light sources 18a to 18c that emit red, blue, or green monochromatic light, respectively. These monochromatic light sources 18a to 18c are individually turned on and off by a control unit (not shown). Other configurations are the same as those of the monochrome liquid crystal display device.
[0118]
Hereinafter, the operation at the time of displaying an image and the operation at the time of reading an image will be described.
[0119]
(1) Operation when displaying images
The red, blue, and green monochromatic light sources 18a to 18c are sequentially turned on selectively, and in each lighting period, the same display as the monochrome image display device is performed based on the display image data of red, blue, or green, respectively. The operation is performed. That is, red, blue, and green components are displayed in a time-division manner for each single pixel, and a color image is displayed by a visual afterimage effect. In this way, by displaying images of each color in a time-division manner by the monochromatic light sources 18a to 18c, one single pixel can act as a color pixel, and the pixel density of the color pixel is made equal to the pixel density of the single pixel. be able to.
[0120]
(2) Operation when reading an image
The red, blue, and green single-color light sources 18a to 18c are sequentially used, and the same reading operation as that of the monochrome liquid crystal display device is performed for each of the single-color light sources 18a. The data is read. More specifically, first, a red monochromatic light source 18a is used, and red light is irradiated on the document via all the transparent pixel electrodes 24, and the amount of reflected light corresponding to the red component in the document image is detected. Next, the blue component image is read using the blue monochromatic light source 18b, and the green component image is read using the green monochromatic light source 18c. By repeating the reading operation three times for the monochromatic light sources 18a to 18c, color image data is read. As described above, by sequentially using the monochromatic light sources 18a to 18c, the image of the red, blue, and green components is read for each single pixel, so that the pixel density is three times that of the case of using the micro color filter. Can read a color image.
[0121]
Note that, similarly to the monochrome liquid crystal display device, the TFT (L) 26 and the TFT (D) 27 are controlled by the common source line 22 and the gate line 23, and a gate line or the like dedicated to the TFT (D) 27 is required. By not doing so, the effective display area of the image can be increased and high visibility can be obtained. However, even when a gate line or the like dedicated to the TFT (D) 27 is provided, the effect of increasing the pixel density is similarly obtained. Can be
[0122]
(Embodiment 6)
An example of a liquid crystal display device having a micro color filter and a high read pixel density will be described.
[0123]
As shown in FIG. 13, the liquid crystal display device transmits a red, green, or blue light corresponding to each transparent pixel electrode 24 between a counter glass substrate 16 and a transparent counter electrode 15 to form a color image. And a micro color filter 61 formed with a display area 61a for performing the above-mentioned display and an illumination area 61b for illuminating the original by transmitting light of all colors.
[0124]
In the transparent counter electrode 15, a region corresponding to the display region 61a or the illumination region 61b of the micro color filter 61 is divided into a display counter electrode 15a and an illumination counter electrode 15b connected to each other. I have. The illumination opposing electrode 15b is connected to the display opposing electrode 15a or is brought into a high impedance state by a switch 62 controlled by a control circuit (not shown). In addition, even if it is not necessarily connected to the display counter electrode 15a, it may be maintained at a predetermined potential.
[0125]
On the other hand, as shown in FIGS. 14 and 15, the transparent pixel electrode 24 formed on the glass substrate 12 has a display connected to a TFT (L) 26 like the transparent pixel electrode 24 in the monochrome liquid crystal display device. Pixel electrode 24a and an illumination pixel electrode 24b connected to the source line 22.
[0126]
Further, similarly to the fifth embodiment, the backlight 18 includes monochromatic light sources 18a to 18c that emit red, blue, or green monochromatic light, respectively.
[0127]
Other configurations are the same as those of the monochrome liquid crystal display device.
[0128]
Hereinafter, the operation at the time of displaying an image and the operation at the time of reading an image will be described.
[0129]
(1) Operation when displaying images
During image display, the red, blue, and green monochromatic light sources 18a to 18c are simultaneously turned on, and function as white light sources. Further, the switch 62 is opened to keep the lighting counter electrode 15b in a high impedance state, and the lighting counter electrode 15b and the lighting pixel electrode 24b are connected regardless of the potential of the lighting pixel electrode 24b, that is, the potential of the source line 22. During this time, the electric charge is not accumulated, and the light from the backlight 18 is always controlled to be shielded. When a normally white liquid crystal display device in which light is transmitted when a voltage is not applied to the liquid crystal layer 14 is formed, the illumination counter electrode 15b is not in a high impedance state but has a sufficient absolute value. What is necessary is just to make it apply a large predetermined voltage.
[0130]
In this state, a color image is displayed by performing the same operation as in the fourth embodiment. That is, the same operation as in the fourth embodiment is performed except that the light incident on the illumination pixel electrode 24b in the pixel is always shielded, and the display pixel electrode 24a, the liquid crystal layer 14, and the micro color filter 61 A color image is displayed by the additive color mixture of the light transmitted through the display area 61a.
[0131]
In this liquid crystal display device, since the portion of the pixel electrode 24b for illumination in the pixel is in a light-shielding state, the aperture ratio is slightly reduced. However, the liquid crystal display device of the fifth embodiment performs display by time division. On the other hand, since each single pixel always emits light according to the image data, the frame period can be set to a desired length without causing flicker.
[0132]
(2) Operation when reading an image
At the time of reading an image, as shown in Tables 4 to 6, operations different from the operations of the monochrome liquid crystal display device in the following points are performed. However, as for the illumination of the original, red, blue, and green monochromatic light sources 18a to 18c are sequentially used as in the fifth embodiment.
[Table 4]

[Table 5]

[Table 6]

[0133]
That is, in the step of accumulating charges between the transparent pixel electrode 24 and the transparent counter electrode 15 in Tables 1 to 3, the source voltage Vs = VsLmin is output to the source line 22, and the display pixel electrode 24a is connected to the display pixel electrode 24a. Electric charges between the counter electrode 15a and the display pixel electrode 24a in the pixel are shielded from light. Thus, the effect of transmitting only the red, blue, or green light of the display area 61a in the micro color filter 61 does not affect image reading.
[0134]
In the step of exposing the photodiode 25 by the reflected light from the original, the illumination counter electrode 15b is connected to the display counter electrode 15a via the switch 62, and the source voltage Vs = VsLmax corresponding to the maximum luminance. Is applied to the illumination pixel electrode 24b via the source line 22, and the illumination pixel electrode 24b in the pixel enters a light transmitting state. Therefore, since the illumination area 61b of the micro color filter 61 transmits light of all colors as described above, any one of the monochromatic light sources 18a to 18c emitted from the monochromatic light sources 18a to 18c of red, blue, or green is used. The light is also directly irradiated on the original. Therefore, as in the fifth embodiment, red, blue, and green monochromatic light sources 18a to 18c are sequentially used, and the same reading operation as that of the monochrome liquid crystal display device is performed for each monochromatic light source 18a. Thereby, the image data of each color component in the document image is read.
[0135]
As described above, when an image is displayed, a color image is displayed by additive color mixing of three single pixels using a micro color filter. On the other hand, when an image is read, a single color of red, blue, and green is displayed for each single pixel. By reading the components of each color using the light sources 18a to 18c, a document image can be read with a pixel density three times as high as that in display.
[0136]
【The invention's effect】
The present invention is implemented in the form described above, and has the following effects.
[0137]
That is, without providing a source line and a gate line for the second transistor connected to one end of the light receiving element, a source line and a gate line common to the first transistor connected to each pixel electrode are used. Since only the second transistor is turned on and the original image detected by the light receiving element can be read, the size of the apparatus can be reduced and the operability can be improved without lowering the visibility due to a decrease in the effective display area of the image. , And the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating an external configuration of a liquid crystal display device with an image reading function according to a first embodiment.
FIG. 2 is an explanatory diagram illustrating a circuit configuration of an active matrix panel 13 according to the first embodiment.
FIG. 3 is a plan view showing a specific configuration of an active matrix panel 13 according to the first embodiment.
4 is a sectional view taken along arrows AA and BB in FIG.
FIG. 5 is an explanatory diagram illustrating a method for manufacturing the active matrix panel 13 of the first embodiment.
FIG. 6 is a plan view showing a specific configuration of an active matrix panel 13 according to a second embodiment.
FIG. 7 is a sectional view taken along arrows AA and BB of FIG. 6;
FIG. 8 is a circuit diagram showing a modification (another connection example of the photodiode 25) of the liquid crystal display device with an image reading function according to the third embodiment.
FIG. 9 is a circuit diagram showing another modification (an example in which a source voltage is applied to the anode side of the photodiode 25) of the liquid crystal display device with an image reading function according to the third embodiment.
FIG. 10 is an explanatory diagram showing an example of a case where an in-plane switching type liquid crystal display device is configured.
FIG. 11 is a perspective view illustrating an external configuration of a liquid crystal display device with an image reading function according to a fourth embodiment.
FIG. 12 is a perspective view illustrating an external configuration of a liquid crystal display device with an image reading function according to a fifth embodiment.
FIG. 13 is a perspective view showing an external configuration of a liquid crystal display device with an image reading function according to a sixth embodiment.
FIG. 14 is a plan view showing a specific configuration of an active matrix panel 13 according to a sixth embodiment.
15 is a sectional view taken along arrows AA and BB in FIG.
[Explanation of symbols]
11 Polarization filter layer
12 Glass substrate
13 Active matrix panel
14 Liquid crystal layer
15 Transparent counter electrode
15a Counter electrode for display
15b Counter electrode for lighting
16 Opposite glass substrate
17 Polarization filter layer
18 Backlight
18a Red monochromatic light source
18b Blue monochromatic light source
18c Green monochromatic light source
19 Touch panel unit
21 Display / read unit
22 source lines
23 Gate line
24 Transparent pixel electrode
24a Display pixel electrode
24b Illumination pixel electrode
25 Photodiode
26 TFT (L)
27 TFT (D)
28 Shielding electrode
31 Drive circuit section
32 shift register
33 TFT control circuit
34 shift register
35 Charge voltage output circuit
35a line memory
35b D / A converter
36 reading circuit
36a A / D converter
36b line memory
61 Micro Color Filter
61a Display area
61b Lighting area
62 switch
71 Control unit

Claims (15)

A plurality of source lines for transmitting image signals,
A plurality of gate lines provided in a direction intersecting with the source line and transmitting a scanning signal;
A pixel electrode provided corresponding to each intersection of the source line and the gate line;
A first transistor connected to each pixel electrode and connected to a source line and a gate line;
A counter electrode provided to face the pixel electrode;
A liquid crystal provided between the pixel electrode and the counter electrode,
A liquid crystal display device with an image reading function, which is provided corresponding to each pixel electrode and includes a light receiving element for detecting the amount of reflected light from a document,
The light receiving element is a light receiving element that detects the amount of light reflected from the document by discharging a previously held charge by reflected light from the document,
A second transistor connected to one end of the light receiving element and connected to the source line and the gate line;
A second line connected to the other end of the light receiving element,
The threshold value of the gate voltage of the first transistor and the threshold value of the gate voltage of the second transistor are set so that at least only the second transistor can be turned on . It is set so that it can be turned on simultaneously with the transistor of
A liquid crystal display device with an image reading function, wherein the liquid crystal is configured to be in a light transmitting state when an electric field is applied . The liquid crystal display device with an image reading function according to claim 1 ,
The first transistor and the second transistor are n-channel or p-channel transistors having the same polarity;
A liquid crystal display device with an image reading function, wherein the absolute value of the threshold value of the gate voltage of the second transistor is set lower than the absolute value of the threshold value of the gate voltage of the first transistor. The liquid crystal display device with an image reading function according to claim 1 or 2 ,
The dielectric anisotropy of the liquid crystal is negative,
A liquid crystal display device with an image reading function, wherein a pair of polarizing plates having different polarization directions is provided on both sides of the liquid crystal. The liquid crystal display device with an image reading function according to claim 1 or 2 ,
The dielectric anisotropy of the liquid crystal is positive,
A liquid crystal display device with an image reading function, wherein a pair of polarizing plates having the same polarization direction are provided on both sides of the liquid crystal. The liquid crystal display device with an image reading function according to claim 1, further comprising a photodiode as the light receiving element.
A liquid crystal display device with an image reading function, wherein the photodiode is connected so that a reverse bias voltage is applied from a source line via a second transistor when an image is displayed. The liquid crystal display device with an image reading function according to claim 1 , wherein:
A liquid crystal display device with an image reading function, wherein a voltage equal to that of a source line is applied to the other end line connected to the other end of the light receiving element when displaying an image. The liquid crystal display device with an image reading function according to claim 1 , wherein
A liquid crystal display device with an image reading function, wherein a light-shielding electrode formed on the same substrate as the light-receiving element is a line on the other end connected to the other end of the light-receiving element. 8. The liquid crystal display device with an image reading function according to claim 1, wherein the pixel electrode and the counter electrode are formed on the same substrate and are of an in-plane switching type.
A liquid crystal display device with an image reading function, wherein the counter electrode is a line on the other end connected to the other end of the light receiving element. 9. The liquid crystal display device with an image reading function according to claim 1 , further comprising a touch sensor provided on a front side of the liquid crystal for detecting an installation state of the document. The light-receiving element, by charges stored in advance are discharged by the reflected light from the original, the image reading function liquid crystal display according to claim 1 to claim 9 which is a light receiving element for detecting the amount of light reflected from the document An image reading method using
Applying a predetermined first voltage to the source line, turning on at least the first transistor, and bringing the liquid crystal into a light-transmitting state;
Applying a predetermined second voltage to the source line, turning on at least the second transistor, and holding a predetermined charge in the light receiving element;
Exposing the light receiving element with reflected light from the document;
Detecting the exposure amount of the light receiving element via the source line by turning on only the second transistor after the step of exposing the light receiving element. An image reading method according to claim 10 , wherein the liquid crystal display device with an image reading function according to any one of claims 1 to 5 is used.
The first voltage and the second voltage are equal to each other,
An image reading method, wherein the step of causing the liquid crystal to transmit light and the step of causing the light receiving element to hold a predetermined charge are performed simultaneously. 10. The method of manufacturing a liquid crystal display device with an image reading function according to claim 1, wherein the other end of the light receiving element is connected to a first transistor or a second transistor. A method of manufacturing a liquid crystal display device with an image reading function, which is formed in a step of forming at least one gate electrode. The liquid crystal display device with an image reading function according to claim 1, further comprising:
Corresponding to the pixel electrode, a color filter in which a region for transmitting light of a predetermined color is formed,
At the time of image display, a color image is displayed by an additive color mixture of light transmitted through each color region in the color filter,
When reading an image, an image reading function is configured to read a color image by detecting the amount of reflected light that is transmitted to the original through the respective color regions of the color filter and reflected. With LCD display. The liquid crystal display device with an image reading function according to claim 1, further comprising:
Equipped with multiple back light sources that emit light of different colors from each other,
At the time of displaying an image, a color image is displayed by selectively illuminating each of the back light sources sequentially and displaying images of each color in a time division manner.
At the time of reading an image, each of the back light sources is sequentially selectively turned on to irradiate the original with light of each color, and a color image is read by detecting the amount of reflected light of each color of light from the original. A liquid crystal display device with an image reading function. The liquid crystal display device with an image reading function according to claim 1, further comprising:
For each pixel, a color filter in which a display area that transmits light of a predetermined color and an illumination area that transmits light of all colors are formed,
Each emits light of a different color from each other, and includes a plurality of back light sources that emit white light when lit simultaneously.
At the time of displaying an image, while the liquid crystal in the portion corresponding to the illumination region of the color filter is in a light-shielding state, the liquid crystal in the portion corresponding to the display region is in a light-transmitting state in accordance with an image signal, Turn on the back light source, display a color image by additive color mixture of light transmitted through the display area of each color in the color filter,
At the time of reading the original image, the liquid crystal in the portion corresponding to the display area of the color filter is set in a light-shielding state, while the liquid crystal in the portion corresponding to the illumination area is set in a light-transmitting state, and each of the back light sources is sequentially selected. The color image is read by illuminating the original, irradiating the original with the light of each color through the illumination area in the color filter, and detecting the amount of reflected light of each color from the original. A liquid crystal display device having an image reading function.

Images