200526010 (1) 九、發明說明 【發明所屬之技術領域】 本發明係關於適用於畫像掃描器、傳真機以及影印 機等之畫像感測器單元以及畫像讀取裝置；特別是讀取 由原稿面而來的反射光之畫像感測器單元以及畫像讀取 裝置。 【先前技術】 以往’於畫像掃描器、傳真機以及影印機等畫像讀 取裝置中，使用接觸型畫像感測器（以下略稱CIS)以作 爲讀取由原稿面而來的反射光之畫像讀取手段之一。 此接觸型畫像感測器具有照射原稿用之光源，透過 鏡片接收反射光，並以光電轉換素子所形成之受光部將 反射光轉換爲電氣畫像。近年來，伴隨畫像讀取裝置之 讀取速度的高速化，爲了縮短讀取時間，而要求增強照 明光強度。於是，夾透鏡陣列（L e n s A r r a y )而使2系統 之照明裝置面對面，以增大照射光量之技術被公開（例 如專利文獻1 (日本特開2 002 - 5 7 8 5 3號公報））。 接觸型畫像感測器單元（CIS單元）係被設置在支持 原稿之透明原稿支持體之下方而使用。於畫像讀取裝置 內之畫像感測器單元之設置方法主要有下述2種。 (1 )將感測器單元固定於畫像讀取裝置，移動原稿 支持體上之原稿以進行讀取之饋紙（Sheei-feed )型。 (2)將原稿固定於畫像讀取裝置之原稿支持體上， -4- 200526010 (2) 移動感測器單元以進行讀取之平台（Flatbed )型。 於此說明以往之CIS單元之構造例。第8圖係表示 以往之CIS單元之構造之斷面圖。於以往之CIS單元中 ，框架1 1支持了，搭載照明原稿所用之LED之光源15a 及15b，以及照明裝置16a及16b。照明裝置16a及16b 係由，分別接收光源15a及15b之出射光，使照明光量 略爲均勻地射出至原稿讀取部之1線（Line )之長度之 導光體而構成。又，框架11之下方設有，搭載了具備複 數個將原稿之光學像光電轉換爲電氣訊號之受光部之線 狀感測器陣列1 3之感測器基板1 4 ;框架1 1支持了使原 稿之光學像在感測器陣列1 3上成像之jf鏡陣列1 2。又， 感測器基板1 4之下方設有，連接感測器陣列1 3與外部 機器之連接器17。此種以往之CIS單元如上所述，係裝 置於原稿支持體18之下方。 於此CIS單元，爲了增大照明原稿之照明裝置之光 量，由光源及照明裝置所構成之照明系統設有二個；且 此二系統夾透鏡陣列1 2，被面對面設置在對稱之位置上 。’又，照明裝置1 6a及1 6b之光線射出部上設有集光機 能，故光的利用效率局。 例如，將透鏡陣列1 2之原稿側焦點A設於，較原稿 支持體1 8之原稿側表面位置略爲上方，且離開透鏡陣列 1 2之位置上，以集中二系統之照明裝置射出之光。亦即 ，透鏡陣列1 2之被寫界深度被設爲較深。此種構造使得 ，於饋紙型畫像讀取裝置，伴隨饋紙速度之高速化而生 -5- 200526010 (3) 之原稿與原稿支持體間之接觸摩擦過大之問題，可以被 避免；又，於平台型畫像讀取裝置，表面凹凸不平之原 稿亦可輕易地被讀取。 專利文獻1中提供了，將由光源而來的照明光之尖 峰位置放在透鏡陣列之原稿側焦點之略上方，以使即使 原稿用紙由原稿支持體略爲浮上，亦可以穩定光量來進 行讀取之構造。 依此由面對面二方向來照射原稿之方法，於增加照 明原稿之光量的同時，亦可使原稿上之凹凸不平等之表 面狀態所產生的影子變少，而提高讀取畫像的品質。 然而，此種之先前技術有以下的課題待解決。 爲求更高速之讀取，必須提高由光源而來的光的利 用效率，故必須集中導光體之光射出部所射出之光，以 增加光量。於是，於專利文獻1，爲了使用複數個照明裝 置以增加照明原稿之光量，故集中二個光源之焦點位置 以增加光量。然而，此構造提高了導光體之集光性，使 得照明光之合成光量分布尖銳化，而有以下之副作用。 第9圖係表示使用以往之CIS單元之高速饋紙型畫 像讀取裝置之斷面圖。此畫像讀取裝置上設有，與原稿 支持體18面對面之壓板27;原稿支持體18與壓板27之 間的空間爲送紙路徑2 8。又’設有原稿運送滾筒2 5以夾 住送紙路徑2 8 ;原稿2 6被原稿運送滾筒2 5於送紙路徑 2 8內運送。壓板2 7之高度係設定爲，使原稿側焦點a 位於送紙路徑2 8之中央。 -6· 200526010 (4) 於使用此種CIS單元之高速饋紙型畫像讀取裝置， 原稿2 6通過送紙路徑2 8時，原稿2 6相對於透鏡陣列1 2 之光軸方向之位置，係於以原稿側焦點A爲基準之遠近 二方向（透鏡陣列1 2之光軸方向）上變動。送紙路徑2 8 之寬度P意謂原稿26搖動，而該位置變動之最大幅度。 而’若原稿2 6之位置往透鏡陣列1 2之光軸方向變動， 由於原.稿2 6之表面係垂直於透鏡陣列1 2之光軸，故原 稿26之表面上的照明光量會變化。因此，原稿26之濃 度即使爲均勻，於讀取裝置的輸出畫像，亦容易發生因 讀取位置之高度變動所致之濃度變動。 又’於以往的平台型畫像讀取裝置亦如上所述，一 般而言，爲使表面凹凸不平之原稿容易被讀取，將透鏡 陣列1 2之原稿側焦點A設於原稿支持體1 8之原稿側表 面位置之上方。因此，原稿位置在透鏡陣列1 2之光軸方 向上變動時，容易發生濃度變動。 爲了抑制此種濃度變動，於透鏡之被寫界深度範圍 內，將照明光之光量變動之容許範圍設爲1 〇 %以內。 於是，在專利文獻2 (日本特許第2848477號公報） 中記載了，配置二系統之光源，使各光源之照射位置在 受光素子之光軸上上下滑動，以使於成像手段之被寫界 深度之範圍內，原稿面之照度大略維持一定。此種構造 使得合成光量分布均勻化，即使原稿位置發生偏移，亦 可抑制讀取光量之變動。· 然而’此構造雖提高了光量分布之均勻性，但合成 -7- 200526010 (5) 光量本身並未增加，故亦不適用於高速讀取。 如此，使用複數光源時，合成光量之增大，以及其 光量分布之均勻化之間，有著兩難（Trade-off )的關係 。亦即，重視均勻性’則合成光量分布之尖銳性就減少 ，其尖峰光量也跟著減少。 (專利文獻1)日本特開2002-578 5 3號公報 (專利文獻2 )日本特許第2848477號公報 【發明內容】 本發明鑑於相關情形，目的在提供可得高照射光量 ，並可抑制伴隨原稿高度之變動而來的讀取光量變動之 畫像感測器單元以及畫像讀取裝置。 與本發明相關之畫像感測器單元，係具有照明原稿 之第1及第2照明裝置、將由原稿而來的反射光成像之 成像手段、具備複數個將上述反射光轉換爲電氣訊號之 畫素之感測器陣列（Sensor Array )之畫像感測器單元； 其特徵爲，上述第1及第2照明裝置被面對面地配置於 上述成像手段之兩側；若上述成像手段之有效被寫界深 度爲a ’則沿上述成像手段之光軸之各照明裝置之光量分 布曲線之90 %値幅均在a以上；上述第1照明裝置之出 射光之光軸與上述成像手段之光軸之第1交點，在較上 述成像手段之原稿側焦點接近上述成像手段之位置上； 上述第2照明裝置之出射光之光軸與上述成像手段之光 軸之第2交點，在較上述成像手段之原稿側焦點遠離上 -8- 200526010 (6) 述成像手段之位置上；上述第1及第2交點與上述原稿 側焦點之距離均在a/ 2以下。 於本發明中，由於第1及第2交點係以原稿側焦點 爲基準而往相互不同方向偏移，故沿成像手段之光軸之 合成光量之變動被抑制。又，由於偏移的大小以及各照 明裝置之光量分布曲線被適切地規定，故成像手段之有 效被寫界深度a之範圍內之光量變動在10%以內，同時 ，合成光量之尖峰値爲照明裝置只有1個時之180%以上 。從而，得到高照射光量之同時，伴隨原稿高度之變動 而來的讀取光量變動也被抑制。 【實施方式】 以下參照附加圖面，具體說明本發明之實施形態。 (第1實施形態） 首先說明本發明之第1實施形態。第1圖係表示與 本發明之第1實施形態相關之CIS單元之構造之斷面圖 。於本實施形態’框架1支持了照明原稿之照明裝置5 及6。框架1之下方設有，搭載了具備複數個將原稿之光 學像光電轉換爲電氣訊號之受光部之感測器陣列3之感 測器基板4 ;框架1亦支持了使原稿之光學像在感測器陣 列3上成像之透鏡陣列（成像手段）2。感測器陣列3位 於透鏡陣列2之感測器側焦點。又’感測器基板4之下 方設有，連接感測器陣列3與外部機器之連接器7 °並且 200526010 (7) ，照明裝置5及6上設有LED以作爲光源。 照明裝置5及6夾透鏡陣列1 2，被面對面地設置。 又，透鏡陣列2之光軸Z1與照明裝置5之光軸Z2之基 準點5 a之水平距離X1，較光軸Z1與照明裝置6之光軸 Z3之基準點6a之水平距離x2爲短。並且，於本實施形 態，照明裝置5被配置爲，其光軸Z2與光軸Z1之交點 B較透鏡陣列2之原稿側焦點A靠近透鏡陣列2。而，照 明裝置6被配置爲，其光軸Z3與光軸Z1之交點C較透 鏡陣列2之原稿側焦點A遠離透鏡陣列2。 又，照明裝置5及6被配置爲，焦點A與交點B之 距離，以及焦點A與交點C之距離，„相互實質上相等。 並且，若透鏡陣列2之有效被寫界深度爲a，則焦點A 與交點B之距離，以及焦點A與交點C之距離，均在 a/ 2以下。 並且，沿透鏡陣列2之光軸之照明裝置5及6之光 量分布曲線之90%値幅均在a以上。於此，參照第2圖 ，說明光軸及照明裝置5之光量分布曲線之90%値幅。 透鏡陣列2之光軸Z 1係，將透鏡陣列2之原稿側焦 點A與感測器側焦點D連結起來的線。又，照明裝置5 之光軸Z2係照明裝置5之出射光之光軸，並如第2圖所 示，亦爲改變由原稿支持體（未圖示）起算之原稿面〇 之高度並將出射光投射於原稿面Ο上之時，往與原稿面 〇垂直相交之方向之反射光的光量分布曲線S之尖峰位 置之連結線。而，感測器陣列3被配置在感測器側焦點 -10- 200526010 (8) D上。 又，照明裝置5之光量分布曲線之90%値幅係，於 表示沿透鏡陣列2之光軸Z 1移動原稿面0時之’光軸 Z 1與原稿面Ο之交點（讀取點）上之照明光強度之分布 之分布曲線I ( Z )中，其照明光強度爲尖峰値的90%以 上之原稿面〇之移動範圍幅度w。 照明裝置6之光軸Z 3及光量分布曲線之9 0 °/〇亦相同 〇 而，基準點5 a及5 b之於透鏡陣列2之光軸方向上 的高度一致。此種CIS單元被設置在支持原稿之透明原 稿支持體8之下方。 於此種構造之與第1實施形態相關之CIS單元中， 當原稿位於焦點A附近時，照明裝置5及6之照明光量 大略相等；原稿被這些光的總和所照射。 由此狀態起，當原稿往較焦點A接近透鏡陣列2之 方向偏移時，照明裝置5之照明光量增加，同時照明裝 置6之照明光量減少；原稿被這些光的總和所照射。 相反地，當原稿往較焦點A遠離透鏡陣列2之方向 偏移時，照明裝置5之照明光量減少，同時照明裝置6 之照明光量增加；原稿被這些光的總和所照射。 從而，無論原稿由焦點A沿透鏡陣列2之光軸Z 1往 哪一個方向移動，亦即，無論自原稿支持體8起算之原 稿高度如何變動’照明裝置5及6之照射光量之變動會 互相抵消，照射在原稿上的合成光量幾乎不變。結果， -11 - 200526010 Ο) 依本實施形態，可減輕畫像讀取裝置之輸出畫像所發生 之濃度變動。 其次說明，本申請之發明者實際製作具備與第1實 施形態相同構造之c I S單元之饋紙型畫像讀取裝置，並 測定光量分布之結果。 此饋紙型畫像讀取裝置中，透鏡陣列2之有效被寫 界深度a爲±0.3 mm，送紙時之位置變動幅度P爲0.6mm ，透鏡陣列2之原稿側焦點A之位置在原稿支持體1 8之 表面起算〇.3mm之點上。 此時，透鏡陣列2之光軸方向上之原稿位置變動爲 ，以原稿側焦點A爲基準，最大可達± 0.3 mm。依此，於 此範圍，照明光量分布之變動必須要小。 又，使光軸Z1與照明裝置5內之基準點5 a之距離 xl較光軸Z1與照明裝置6內之基準點6a之距離x2小 0.3mm左右。 第3圖係表示，如上所述所製作之饋紙型畫像讀取 裝置（實施例），以及採用第8圖所示構造之饋紙型畫 像讀取裝置（先前例）之被寫界深度特性（照明深度特 性）。第3圖係表示，自原稿支持體1 8之表面起算之高 度dL與各種相對光量之關係之曲線圖。 於先前例之相對光量分布曲線（·與實線）’原稿 之位置變動幅度P之±0.3mm範圍內，發生了大約5 %的 光量變動。相對於此，實施例之相對光量分布曲線（〇 與實線）中之光量變動約2%，十分微小。 -12- 200526010 (10) 於此，實施例之光量分布係由照明裝置5所致之相 對光量分布與照明裝置6所致之相對光量分布合成而得 〇 而，第3圖所示相對光量係以，照明裝置5之照明 光的光量分布、照明裝置6之照明光的光量分布、於實 施例所得之光量分布、以及於先前例所得光量分布，分 別成爲最大之光量爲基準時之相對光量。 第4圖係表示自原稿支持體18之表面起算之高度 dL與以1個照射裝置之照射光量爲基準時之相對光量之 關係之曲線圖。 於先前例，由於二個照明裝置之焦點位置一致，故 將之合成而得到的光量分布的尖峰光量約有2.0之大， 但光量分布的尖銳性較大。因此’原稿位置的偏移使得 光量急遽變動。 相對於此，於實施例，尖峰光量（1 .9 1 )雖然略小 於先前例，但光量分布曲線之尖銳性小，透鏡陣列2之 被寫界深度內之光量變化顯著降低。亦即’即使原稿位 置發生偏移，光量的變動亦不大。從而，讀取光量的誤 差也變小。又，光量若爲1.91’十分高速之讀取亦爲可 能。 如此，依第1實施形態’交點B及C自透鏡陣列2 之原稿側焦點A滑動，故可得和緩之光量分布曲線。 又，於透鏡陣列2之被馬界诛度爲a之時’右原稿 側焦點A與交點B及C之偏移大小爲a / 2之同時，由 -13- 200526010 (11) 於照明裝置5及6之各照射光之光量分布曲線之90%値 幅在a以上，故若照明裝置5及6之各照射光之尖峰光 量爲1，則照射在原稿上的光的尖峰光量至少爲1 . 8。從 而，可得充分之光量，高速讀取成爲可能。相對於此， 令人懸念的是，若偏移大小超過a/ 2，或者光量分布曲 線之90%値幅未達a，則即使將照明裝置5之照射光及照 明裝置6之照射光加起來，亦無法得到充分的尖峰光量 〇 偏移大小如上所述，於被寫界深度爲a時，在±a/2 以內者爲佳，但此範圍內，即使有些微變動，亦可得同 樣效果。 亦即，於第1實施形態，不僅交點B及C自透鏡陣 列2之原稿側焦點A之滑動’其偏移的大小以及照明裝 置5及6之照射光之光量分布曲線均被適切地規定，故 可確保充分的合成光量，並得到和緩之光量分布曲線。 (第2實施形態） 其次說明本發明之第2實施形態。第5圖係表示與 本發明之第2實施形態相關之CIS單元之構造之斷面圖 。而，與第1圖所示第1實施形態相同之構成要素，賦 予相同符號。 於本實施形態，感測器陣列3之表面起算之基準點 5 a的局度h 1，較感測器陣列3之表面起算之基準點6 a 之高度h2爲低。並且，於本實施形態，照明裝置5亦被 -14- 200526010 (12) 配置爲，其光軸Z2與光軸Z1之交點B較透鏡陣列2之 原稿側焦點A靠近透鏡陣列2 ;照明裝置6亦被配置爲 ’其光軸Z3與光軸Z1之交點C較透鏡陣列2之原稿側 焦點A遠離透鏡陣列2。 又，於本實施形態，照明裝置5及6亦被配置爲， 焦點A與交點B之距離，以及焦點A與交點C之距離， 實質上相等。並且，若透鏡陣列2之有效被寫界深度爲a ，則焦點A與交點B之距離，以及焦點A與交點C之距 離，均在a/ 2以下。 依此種構造之第2實施形態，亦可得到與第丨實施 形態相同之效果。 ^ (第3實施形態） 其次說明本發明之第3實施形態。第6圖係表示與 本發明之第3實施形態相關之CIS單元之構造之斷面圖 。而，與第1圖所示第1實施形態相同之構成要素，賦 予相同符號。 於本實施形態，光軸Z 1與基準點5 a及6 a距離相同 ，且感測器陣列3之表面起算之基準點5a及6a之高度 亦相同；不過，框架1之支持照明裝置5之部份向內側 傾斜，框架1之支持照明裝置6之部份向外側傾斜。因 此，與第1實施形態比較，照明裝置5及6被往順時針 方向迴轉移動；並且’其照明光之光軸Z2及Z3亦以順 時針方向迴轉移動。因此，光軸Z2與光軸zi所成角度 -15- 200526010 (13) ，與光軸Z3與光軸Z1所成角度並不相同。並且，於本 實施形態，照明裝置5亦被配置爲，其光軸Z2與光軸 Z 1之交點B較透鏡陣列2之原稿側焦點A靠近透鏡陣列 2 ;照明裝置6亦被配置爲，其光軸Z 3與光軸Z1之交點 C較透鏡陣列2之原稿側焦點A遠離透鏡陣列2。 又，於本實施形態’照明裝置5及6亦被配置爲， 焦點A與交點B之距離，以及焦點A與交點C之距離， 實質上相等。並且，若透鏡陣列2之有效被寫界深度爲a ，則焦點A與交點B之距離，以及焦點A與交點C之距 離，均在a/2以下。 依此種構造之第3實施形態，亦可得到與第i實施 形態相同之效果。 (第4實施形態） 其次說明本發明之第4實施形態。第4實施形態係 ，使用第1至第3實施形態之任一之平台型畫像掃描器 (畫像讀取裝置）。第7圖係表示與本發明之第4實施 形態相關之平台型畫像掃描器之外觀之斜視圖。 於第4實施形態’ CIS單元71被收納於筐體72內部 :且於筐體72內部設有，移動CIS單元71所用之驅動 馬達7 4及鋼絲7 5。筐體7 2上面貼有玻璃板7 6以作爲原 稿支持體。又，筐體72之端部上設有可開閨之原稿壓板 77 ° 於如此構造之本實施形態’驅動驅動馬達7 4而使鋼 -16- 200526010 (14) 絲7 5機械地動作，以使CIS單元7 1往讀取方向（掃描 方向）移動，而可讀取原稿之畫像。CIS單元71之構造 係照明部被一體納入之感測器單元；被光照射之原稿所 反射之光因CIS單元71中之透鏡陣列（未圖示）而被光 電轉換素子集光，每一掃描線被作爲畫像資訊而輸出。 如此則可讀取輸出頁狀之畫像資訊。 於第4實施形態所相關之畫像掃描器中，具備CIS 單元71，故不易受到原稿用紙之位置變動與凹凸不平所 致影響，而可輸出穩定的畫像資訊。 本申請之發明者實際製作具備與第4實施形態相同 構造之畫像掃描器；以此畫像掃描器所得之讀取畫像之 濃度分布較以往者有顯著改善，即使在原稿凹凸不平時 ，亦可得良好之讀取畫像。並且，由於光量提局，故即 使將掃描器的讀取速度比以往提高約二倍，亦可得良好 之畫像。 其次說明採用專利文獻2所記載之構造（先前技術 )所得之光量。第1 〇圖係表示專利文獻2所記載之構造 (先前技術）之模式圖。又，第1 1圖係表示以第1 〇圖 所示構造所得之光量分布曲線圖。 於此構造，爲了達成專利文獻2所記載之發明之目 的，照射光之光量分布曲線之半値幅採用了與透鏡陣列 1 2之被寫界深度a —致之値，以作爲照明裝置1 6 a及 1 6 b ;同時’使各照明裝置之照射光的光軸在透鏡陣列1 2 之光軸之平行方向上’自焦點A各偏移a/ 2，以決定照 -17- (15) (15)200526010 明裝置16a及16b之高度。 而’以如此之構造所得之合成光量分布曲線（第11 圖中的實線）中，尖峰形狀變得平坦，被寫界深度a中 原稿上的光量變動dl大約改善了 2%，尖峰形狀變平坦 ’而可實現合成光量分布之平坦化。 然而，即使使用了二系統之光源，.如第1 1圖所示， 合成光量較光源爲一系統時，亦僅增加了 5%。從而，如 專利文獻2所記載之發明，若僅僅考慮合成光量分布的 平坦化來移動各光軸之照射裝置的高度，則對於進行高 速讀取而言，原稿上的合成照射光量並不充足。 產業上之可利用性 依本發明，可得高照射光量，同時可抑制伴隨原稿 高度之變動而來的讀取光量變動。從而，可因應於掃描 器等畫像讀取裝置中之讀取速度之高速化。又，於被寫 界深度範圍內，可減低讀取畫像之濃度分布。因此，對 於高速掃描器等畫像讀取裝置相當有用。 【圖式簡單說明】 第1圖係表示與本發明之第1實施形態相關之CIS 單元之構造之斷面圖。 第2圖係表示光軸及照明裝置5之光量分布曲線之 90%値幅之模式圖。 第3圖係表示自原稿支持體18之表面起算之高度 -18- 200526010 (16) dL與各種相對光量之關係之曲線圖。 第4圖係表示自原稿支持體18之表面起算之高度 dL與以1個照射裝置之照射光量爲基準時之相對光量之 關係之曲線圖。 第5圖係表示與本發明之第2實施形態相關之CIS 單元之構造之斷面圖。 第6圖係表示與本發明之第3實施形態相關之CIS 單元之構造之斷面圖。 第7圖係表示與本發明之第4實施形態相關之平台 型畫像掃描器之外觀之斜視圖。 第8圖係表示以往之CIS單元之構造之斷面圖。 第9圖係表示使用以往之CIS單元之高速饋紙型畫 像讀取裝置之斷面圖。 第1 0圖係表示專利文獻2所記載之構造（先前技術 )之模式圖。 第1 1圖係表示以第1 〇圖所示構造所得之光量分布 曲線圖。 【主要元件符號說明】 1 框架 2 透鏡陣列 3 感測器陣列 4 感測器基板 5 照明裝置 -19- 200526010 (17) 5a 基 準 點 6 昭 明 裝 置 6 a 基 準 點 7 連 接 器 8 原 稿 支 持 體 11 框 架 12 透 鏡 陣 列 13 感 測 器 陣 列 14 感 測 器 基 板 15a > 1 5b 光 源 16a ^ 1 6b 昭 ^\\\ 明裝置 17 連 接 器 18 原 稿 支 持 體 25 原 稿 運 送 滾 筒 26 原 稿 27 壓 板 28 送 不氏 路 徑 7 i CIS . 單： 元 72 筐 體 74 驅 動 馬 達 75 鋼 絲 76 玻 璃 板 77 壓 板 20-200526010 (1) IX. Description of the invention [Technical field to which the invention belongs] The present invention relates to an image sensor unit and an image reading device suitable for an image scanner, a facsimile machine, a photocopier, and the like; in particular, it reads from the original surface The image sensor unit and the image reading device of the reflected light. [Prior Art] Conventionally, in image reading devices such as image scanners, facsimiles, and photocopiers, a contact type image sensor (hereinafter abbreviated as CIS) was used as an image for reading reflected light from the original surface One of the means of reading. This contact type image sensor has a light source for irradiating a document, receives reflected light through a lens, and converts the reflected light into an electrical portrait by a light receiving portion formed by a photoelectric conversion element. In recent years, with the increase in the reading speed of the image reading device, in order to shorten the reading time, it is required to increase the intensity of the illumination light. Therefore, a technique for increasing the amount of light to be irradiated by sandwiching a lens array (Lens Array) to face the illumination devices of the two systems is disclosed (for example, Patent Document 1 (Japanese Patent Laid-Open No. 2 002-5 7 8 5 3)) . The contact type image sensor unit (CIS unit) is used below a transparent original support that supports originals. There are two main methods for setting the image sensor unit in the image reading device. (1) A Sheei-feed type in which the sensor unit is fixed to an image reading device, and the original on the original support is moved for reading. (2) The original is fixed on the original support of the image reading device, 2005-2-010 (2) Flatbed type that moves the sensor unit for reading. Here is an example of the structure of a conventional CIS unit. Fig. 8 is a sectional view showing the structure of a conventional CIS unit. In the conventional CIS unit, the frame 11 supports the light sources 15a and 15b, and the lighting devices 16a and 16b, which are equipped with LEDs used to illuminate the original. The illuminating devices 16a and 16b are composed of light guides that receive the light from the light sources 15a and 15b, respectively, so that the amount of the illuminating light is emitted uniformly to the length of one line of the original reading section. A sensor substrate 1 4 is provided below the frame 11 and is provided with a plurality of linear sensor arrays 13 including a plurality of light-receiving portions that photoelectrically convert an optical image of an original document into electrical signals; the frame 11 supports The optical image of the original is formed on the sensor array 13 by the jf mirror array 12. A connector 17 is provided below the sensor substrate 14 to connect the sensor array 13 to an external device. As described above, such a conventional CIS unit is placed under the original support 18. In this CIS unit, in order to increase the light quantity of the illuminating device for illuminating the original, two illuminating systems composed of a light source and an illuminating device are provided; and the two system clip lens arrays 12 are arranged face to face in symmetrical positions. In addition, since the light emitting portions of the lighting devices 16a and 16b are provided with a light collecting function, the utilization efficiency of the light is limited. For example, the focus side A of the original side of the lens array 12 is set at a position slightly higher than the original side surface of the original support 18, and away from the lens array 12 to concentrate the light emitted by the lighting system of the two systems. . That is, the written bounding depth of the lens array 12 is set to be deep. This structure makes it possible to avoid the problem of excessive contact friction between the original and the original support in the paper-fed image reading device due to the increase in the speed of the paper feed. -5- 200526010 (3) In the platform type image reading device, the original with uneven surface can be easily read. Patent Document 1 provides that the peak position of the illumination light from the light source is placed slightly above the focus of the original side of the lens array, so that even if the original paper is slightly floated from the original support, the light amount can be stabilized for reading Of the structure. According to this method, the original is irradiated from the face to the face in two directions. While increasing the amount of light that illuminates the original, it can also reduce the shadow generated by the uneven surface condition of the original and improve the quality of the read image. However, this prior art has the following problems to be solved. In order to achieve higher speed reading, it is necessary to improve the utilization efficiency of light from the light source, so it is necessary to concentrate the light emitted from the light emitting portion of the light guide to increase the amount of light. Therefore, in Patent Document 1, in order to use a plurality of lighting devices to increase the amount of light for illuminating a document, the focal positions of the two light sources are concentrated to increase the amount of light. However, this structure improves the light-collecting property of the light guide, sharpens the distribution of the synthetic light amount of the illumination light, and has the following side effects. Fig. 9 is a sectional view showing a high-speed paper-fed image reading device using a conventional CIS unit. This image reading device is provided with a pressure plate 27 facing the original support 18; a space between the original support 18 and the pressure plate 27 is a paper feed path 28. Further, a document conveyance roller 25 is provided to sandwich the paper feed path 2 8; the document 2 6 is conveyed by the document conveyance roller 25 in the paper feed path 28. The height of the pressure plate 27 is set so that the original side focus point a is located at the center of the paper feed path 28. -6 · 200526010 (4) In the high-speed paper feed type image reading device using such a CIS unit, when the original 26 passes through the paper feed path 28, the position of the original 26 with respect to the optical axis direction of the lens array 12, It changes in the two directions of far and near (the direction of the optical axis of the lens array 12) based on the original side focus A. The width P of the paper feed path 2 8 means that the original 26 is shaken, and the maximum variation of the position. On the other hand, if the position of the original 26 changes toward the optical axis direction of the lens array 12, since the surface of the original 26 is perpendicular to the optical axis of the lens array 12, the amount of illumination light on the surface of the original 26 will change. Therefore, even if the density of the original 26 is uniform, the output image on the reading device is likely to undergo density changes due to the height variation of the reading position. The conventional platform-type image reading device is also as described above. Generally, in order to make the original with uneven surface easy to read, the original side focus A of the lens array 12 is set on the original support 18. Above the original side surface position. Therefore, when the position of the original document is changed in the optical axis direction of the lens array 12, the density change is liable to occur. In order to suppress such a density variation, the permissible range of the variation of the light amount of the illuminating light is set within 10% within the depth range of the writing boundary of the lens. Therefore, in Patent Document 2 (Japanese Patent No. 2848477), it is described that the light sources of the two systems are arranged so that the irradiation position of each light source slides up and down on the optical axis of the photon, so that the depth of the imaging means is written. Within the range, the illuminance on the original side is maintained approximately constant. Such a structure makes the distribution of the combined light amount uniform, and suppresses variations in the read light amount even if the original position is shifted. · However, although this structure improves the uniformity of the light amount distribution, Synthesis -7- 200526010 (5) The light amount itself does not increase, so it is not suitable for high-speed reading. In this way, when using a plurality of light sources, there is a trade-off relationship between the increase in the amount of synthetic light and the uniformity of the light amount distribution. That is, the importance of uniformity 'reduces the sharpness of the distribution of the synthetic light amount, and the peak light amount also decreases. (Patent Document 1) Japanese Patent Laid-Open No. 2002-578 5 (Patent Document 2) Japanese Patent No. 2848477 [Summary of the Invention] The present invention has been made in view of the related circumstances, and aims to provide a high amount of irradiation light and to suppress accompanying manuscript Image sensor unit and image reading device for reading light quantity fluctuations due to height change. An image sensor unit related to the present invention is provided with first and second illumination devices for illuminating a document, an imaging means for imaging reflected light from the document, and a plurality of pixels for converting the reflected light into an electrical signal. Image sensor unit of a sensor array (Sensor Array); characterized in that the first and second lighting devices are arranged face to face on both sides of the imaging means; If a ', the 90% amplitude of the light amount distribution curve of each lighting device along the optical axis of the imaging means is above a; the first intersection of the optical axis of the light emitted by the first lighting device and the optical axis of the imaging means , At a position closer to the imaging means than the original side of the imaging means; at a second point of intersection between the optical axis of the light emitted by the second illumination device and the optical axis of the imaging means, Keep away from the above 8- 200526010 (6) The position of the imaging means; the distance between the first and second intersections and the focus of the original side are below a / 2. In the present invention, since the first and second intersections are shifted in mutually different directions based on the focus of the original side, variations in the combined light amount along the optical axis of the imaging means are suppressed. In addition, since the magnitude of the offset and the light quantity distribution curve of each lighting device are appropriately specified, the light quantity variation within the range of the effective writing depth a of the imaging means is within 10%, and at the same time, the peak of the combined light quantity is used as illumination. More than 180% of only one device. Therefore, while obtaining a high irradiation light quantity, fluctuations in the reading light quantity accompanying a change in the height of the original are also suppressed. [Embodiment] Hereinafter, an embodiment of the present invention will be specifically described with reference to the attached drawings. (First Embodiment) First, a first embodiment of the present invention will be described. Fig. 1 is a sectional view showing the structure of a CIS unit related to the first embodiment of the present invention. In this embodiment 'frame 1, the lighting devices 5 and 6 for lighting the original are supported. A sensor substrate 4 provided with a sensor array 3 having a plurality of optical receivers for optically converting the optical image of the original into an electrical signal is provided below the frame 1; the frame 1 also supports the optical image of the original Lens array (imaging means) 2 for imaging on the detector array 3. The sensor array 3 is located at the sensor side focal point of the lens array 2. The sensor substrate 4 is provided below the connector 7 ° of the sensor array 3 and an external device, and 200526010 (7). The lighting devices 5 and 6 are provided with LEDs as a light source. The illuminating devices 5 and 6 sandwich the lens array 12 and are provided face to face. The horizontal distance X1 between the optical axis Z1 of the lens array 2 and the reference point 5a of the optical axis Z2 of the lighting device 5 is shorter than the horizontal distance x2 of the optical axis Z1 and the reference point 6a of the optical axis Z3 of the lighting device 6. Furthermore, in the present embodiment, the lighting device 5 is arranged such that the intersection point B of the optical axis Z2 and the optical axis Z1 is closer to the lens array 2 than the original-side focal point A of the lens array 2. The lighting device 6 is arranged such that the intersection point C of the optical axis Z3 and the optical axis Z1 is farther from the lens array 2 than the original side focus A of the lens array 2. The lighting devices 5 and 6 are arranged such that the distance between the focal point A and the intersection point B and the distance between the focal point A and the intersection point C are substantially equal to each other. Further, if the effective bounded depth of the lens array 2 is a, then The distance between the focal point A and the intersection point B, and the distance between the focal point A and the intersection point C are both less than a / 2. Moreover, 90% of the light amount distribution curves of the lighting devices 5 and 6 along the optical axis of the lens array 2 are all at a. Above, here, with reference to Fig. 2, the 90% width of the light axis and the light quantity distribution curve of the lighting device 5 will be described. The optical axis Z 1 of the lens array 2 is the focus A of the original side of the lens array 2 and the sensor side The line connected by the focal point D. The optical axis Z2 of the lighting device 5 is the optical axis of the light emitted by the lighting device 5, and as shown in FIG. 2, the original is counted from the original support (not shown). When the height of the surface 0 is projected onto the original surface 0, the connection line of the peak position of the light quantity distribution curve S of the reflected light in a direction perpendicular to the original surface 0 intersects. The sensor array 3 is arranged On the sensor side focus -10- 200526010 (8) D. Also, the lighting device The 90% amplitude of the light quantity distribution curve of 5 is the intensity of the illumination light at the intersection (reading point) of the 'optical axis Z 1 and the original surface 0 when the original surface 0 is moved along the optical axis Z 1 of the lens array 2 In the distribution curve I (Z) of the distribution, the illumination light intensity is 90% or more of the movement range width w of the original surface of the peak 値. The optical axis Z 3 of the lighting device 6 and the light distribution curve 90 ° / 〇 also Similarly, the heights of the reference points 5 a and 5 b in the optical axis direction of the lens array 2 are the same. This CIS unit is provided below the transparent original support 8 that supports the original. In the CIS unit related to the first embodiment, when the original is located near the focus A, the amounts of illumination light of the lighting devices 5 and 6 are approximately equal; the original is illuminated by the sum of these lights. From this state, when the original is closer to the lens than the focus A When the direction of the array 2 is shifted, the amount of illumination light from the illuminating device 5 increases, and at the same time, the amount of illumination light from the illuminating device 6 decreases; the original is illuminated by the sum of these lights. Conversely, when the original is deviated from the lens array 2 away from the focus A Moving time, lighting device 5 The amount of illumination light is reduced while the amount of illumination light of the illuminating device 6 is increased; the original is illuminated by the sum of these lights. Therefore, it does not matter which direction the original moves from the focus A along the optical axis Z 1 of the lens array 2, that is, regardless of How does the height of the manuscript calculated from the manuscript support 8 change? The changes in the amount of light emitted by the lighting devices 5 and 6 will cancel each other out, and the amount of synthetic light irradiated on the manuscript will hardly change. As a result, -11-200526010 〇) According to this embodiment, Reduce the density variation that occurs in the output image of the image reading device. Next, the inventor of the present application will actually make a paper-fed image reading device having a c IS unit with the same structure as the first embodiment, and measure the amount of light distribution. result. In this paper-feeding type image reading device, the effective writing depth a of the lens array 2 is ± 0.3 mm, and the position variation P when the paper is fed is 0.6 mm. The position of the focus side A of the original side of the lens array 2 is supported by the original. The surface of the body 18 is at a point of 0.3 mm. At this time, the position variation of the original in the optical axis direction of the lens array 2 is, and the maximum is ± 0.3 mm based on the original side focus A. Accordingly, the variation of the distribution of the illumination light quantity within this range must be small. The distance xl between the optical axis Z1 and the reference point 5a in the lighting device 5 is made smaller than the distance x2 between the optical axis Z1 and the reference point 6a in the lighting device 6 by about 0.3 mm. Fig. 3 shows the depth characteristics of the written world of the paper-fed image reading device (example) produced as described above and the paper-fed image reading device (previous example) employing the structure shown in Fig. 8 (Light depth characteristics). Fig. 3 is a graph showing the relationship between the height dL from the surface of the original support 18 and various relative amounts of light. Within the relative light quantity distribution curve (· and solid line) of the previous example, the position variation range P of the original document was within ± 0.3 mm, and a light quantity change of approximately 5% occurred. In contrast, the light quantity variation in the relative light quantity distribution curve (0 and solid line) of the embodiment is about 2%, which is very small. -12- 200526010 (10) Here, the light quantity distribution of the embodiment is obtained by combining the relative light quantity distribution caused by the lighting device 5 and the relative light quantity distribution caused by the lighting device 6 and the relative light quantity system shown in FIG. 3 is obtained. The light quantity distribution of the illumination light of the lighting device 5, the light quantity distribution of the illumination light of the lighting device 6, the light quantity distribution obtained in the embodiment, and the light quantity distribution obtained in the previous example are the relative light quantities when the maximum light quantity is used as a reference. FIG. 4 is a graph showing the relationship between the height dL from the surface of the original support 18 and the relative light amount based on the amount of light irradiated by one irradiation device. In the previous example, since the focal positions of the two lighting devices are the same, the peak light amount of the light amount distribution obtained by combining them is about 2.0, but the sharpness of the light amount distribution is large. Therefore, the deviation of the position of the original causes the light amount to change rapidly. In contrast, in the embodiment, although the peak light amount (1.91) is slightly smaller than the previous example, the sharpness of the light amount distribution curve is small, and the change in the light amount within the depth of the written boundary of the lens array 2 is significantly reduced. That is, 'even if the original position is shifted, the amount of light does not change much. Therefore, the error in the amount of read light is also reduced. It is also possible to read at a very high speed if the amount of light is 1.91 '. In this way, according to the first embodiment, the intersection points B and C slide from the original side focus A of the lens array 2, so that a gentle light intensity distribution curve can be obtained. Also, at the same time when the degree of sacrifice of the lens array 2 is a, the magnitude of the shift between the focus A on the right side of the original document and the points of intersection B and C is a / 2, from -13-200526010 (11) to the lighting device 5 90% of the light quantity distribution curve of each irradiated light and 6 is greater than a, so if the peak light amount of each irradiated light of the lighting devices 5 and 6 is 1, the peak light amount of the light irradiated on the original is at least 1.8 . Therefore, a sufficient amount of light is obtained, and high-speed reading becomes possible. In contrast, if the magnitude of the offset exceeds a / 2, or the 90% width of the light quantity distribution curve does not reach a, even if the irradiation light of the lighting device 5 and the irradiation light of the lighting device 6 are added up, It is also impossible to obtain a sufficient amount of peak light. The magnitude of the offset is as described above. When the depth of the written boundary is a, it is better to be within ± a / 2, but within this range, the same effect can be obtained even if it is slightly changed. That is, in the first embodiment, not only the magnitudes of the shifts of the intersection points B and C from the original side focus A of the lens array 2 and the magnitudes of their offsets, but also the light amount distribution curves of the irradiated lights of the lighting devices 5 and 6 are appropriately defined. Therefore, a sufficient amount of synthetic light can be ensured, and a gentle light intensity distribution curve can be obtained. (Second Embodiment) Next, a second embodiment of the present invention will be described. Fig. 5 is a sectional view showing the structure of a CIS unit related to the second embodiment of the present invention. The same components as those in the first embodiment shown in Fig. 1 are assigned the same reference numerals. In this embodiment, the locality h 1 of the reference point 5 a from the surface of the sensor array 3 is lower than the height h 2 of the reference point 6 a from the surface of the sensor array 3. In addition, in this embodiment, the lighting device 5 is also arranged in -14-200526010 (12) such that the intersection point B of the optical axis Z2 and the optical axis Z1 is closer to the lens array 2 than the focus side A of the original side of the lens array 2; the lighting device 6 It is also arranged that the intersection point C of the optical axis Z3 and the optical axis Z1 is farther from the lens array 2 than the original side focus A of the lens array 2. Moreover, in this embodiment, the lighting devices 5 and 6 are also arranged such that the distance between the focus A and the intersection B and the distance between the focus A and the intersection C are substantially equal. In addition, if the effective bounded depth of the lens array 2 is a, the distance between the focal point A and the intersection point B, and the distance between the focal point A and the intersection point C are both less than a / 2. According to the second embodiment having such a structure, the same effect as that of the first embodiment can be obtained. ^ (Third Embodiment) Next, a third embodiment of the present invention will be described. Fig. 6 is a sectional view showing the structure of a CIS unit according to a third embodiment of the present invention. The same components as those in the first embodiment shown in Fig. 1 are assigned the same reference numerals. In this embodiment, the distance between the optical axis Z 1 and the reference points 5 a and 6 a is the same, and the heights of the reference points 5 a and 6 a from the surface of the sensor array 3 are also the same; however, the frame 1 supports the lighting device 5 A part is inclined inward, and a part of the frame 1 supporting the lighting device 6 is inclined outward. Therefore, compared with the first embodiment, the lighting devices 5 and 6 are rotated in a clockwise direction; and the optical axes Z2 and Z3 of the illumination light are also rotated in a clockwise direction. Therefore, the angle formed by the optical axis Z2 and the optical axis zi is -15-200526010 (13), and the angle formed by the optical axis Z3 and the optical axis Z1 is not the same. Furthermore, in this embodiment, the lighting device 5 is also configured such that the intersection point B of the optical axis Z2 and the optical axis Z 1 is closer to the lens array 2 than the original side focus A of the lens array 2; the lighting device 6 is also configured such that The intersection point C of the optical axis Z 3 and the optical axis Z1 is farther from the lens array 2 than the original side focus A of the lens array 2. Further, in this embodiment, the lighting devices 5 and 6 are also arranged such that the distance between the focus A and the intersection point B and the distance between the focus A and the intersection point C are substantially equal. In addition, if the effective bounded depth of the lens array 2 is a, the distance between the focal point A and the intersection point B and the distance between the focal point A and the intersection point C are both less than a / 2. According to the third embodiment having such a structure, the same effect as that of the i-th embodiment can be obtained. (Fourth Embodiment) Next, a fourth embodiment of the present invention will be described. The fourth embodiment uses a flatbed image scanner (image reading device) according to any of the first to third embodiments. Fig. 7 is a perspective view showing the appearance of a flatbed type image scanner according to a fourth embodiment of the present invention. In the fourth embodiment, the CIS unit 71 is housed inside the casing 72 and is provided inside the casing 72, and a driving motor 74 and a wire 75 for moving the CIS unit 71 are provided. A glass plate 76 is affixed to the housing 72 as an original support. In addition, the end of the casing 72 is provided with a manuscript pressing plate 77 ° which can be opened in this way. In this embodiment, the driving motor 7 4 is driven and the steel -16- 200526010 (14) wire 7 5 is mechanically moved to By moving the CIS unit 71 in the reading direction (scanning direction), the image of the original can be read. The structure of the CIS unit 71 is a sensor unit in which the illumination unit is integrated; the light reflected by the original illuminated by the light is collected by the photoelectric conversion element subset due to the lens array (not shown) in the CIS unit 71, and each scan The lines are output as image information. In this way, the page-shaped image information can be read. The image scanner according to the fourth embodiment is provided with a CIS unit 71, so it is not easily affected by the positional variations and unevenness of the original paper, and can output stable image information. The inventor of the present application actually produced an image scanner having the same structure as that of the fourth embodiment; the density distribution of the read image obtained by the image scanner is significantly improved compared with the previous one, and even when the original is uneven, it can be obtained Good read portrait. In addition, because the amount of light is increased, a good image can be obtained even if the reading speed of the scanner is approximately doubled compared to the past. Next, the amount of light obtained by using the structure (prior art) described in Patent Document 2 will be described. Fig. 10 is a schematic diagram showing a structure (prior art) described in Patent Document 2. Fig. 11 is a graph showing a light amount distribution curve obtained by using the structure shown in Fig. 10. With this structure, in order to achieve the purpose of the invention described in Patent Document 2, the half width of the light amount distribution curve of the irradiated light is adopted to be the same as the written boundary depth a of the lens array 12 as the lighting device 16 a And 16b; at the same time, 'make the optical axis of the illumination light of each lighting device parallel to the optical axis of the lens array 12' from the focal point A by a / 2, to determine the illumination -17- (15) ( 15) 200526010 The height of the devices 16a and 16b. In the synthetic light quantity distribution curve (solid line in Fig. 11) obtained by such a structure, the peak shape becomes flat, and the light quantity variation dl on the original at the writing depth a is improved by about 2%, and the peak shape becomes 'Flat' to achieve flattening of the combined light quantity distribution. However, even if the light source of the two systems is used, as shown in Figure 11, the amount of synthesized light is only 5% higher than when the light source is a system. Therefore, as in the invention described in Patent Document 2, if the height of the irradiation device of each optical axis is moved only by considering the flattening of the combined light amount distribution, the combined irradiation light amount on the document is insufficient for high-speed reading. INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a high amount of irradiation light, and at the same time to suppress a change in the amount of reading light accompanying a change in the height of a document. Therefore, it is possible to respond to the increase in the reading speed in an image reading device such as a scanner. In addition, the density distribution of the read image can be reduced within the depth range of the written boundary. Therefore, it is useful for image reading devices such as high-speed scanners. [Brief Description of the Drawings] FIG. 1 is a sectional view showing the structure of a CIS unit related to the first embodiment of the present invention. Fig. 2 is a pattern diagram showing a 90% width of the light axis and the light amount distribution curve of the lighting device 5. Figure 3 is a graph showing the relationship between the height from the surface of the original support 18 -18- 200526010 (16) dL and various relative amounts of light. FIG. 4 is a graph showing the relationship between the height dL from the surface of the original support 18 and the relative light amount based on the amount of light irradiated by one irradiation device. Fig. 5 is a sectional view showing the structure of a CIS unit according to a second embodiment of the present invention. Fig. 6 is a sectional view showing the structure of a CIS unit according to a third embodiment of the present invention. Fig. 7 is a perspective view showing the appearance of a platform type image scanner according to a fourth embodiment of the present invention. Fig. 8 is a sectional view showing the structure of a conventional CIS unit. Fig. 9 is a sectional view showing a high-speed paper feed type image reading device using a conventional CIS unit. Fig. 10 is a schematic diagram showing a structure (prior art) described in Patent Document 2. FIG. 11 is a graph showing a light amount distribution curve obtained by the structure shown in FIG. 10. [Description of main component symbols] 1 frame 2 lens array 3 sensor array 4 sensor substrate 5 lighting device-19- 200526010 (17) 5a reference point 6 Zhaoming device 6 a reference point 7 connector 8 original support 11 frame 12 Lens array 13 Sensor array 14 Sensor substrate 15a > 1 5b Light source 16a ^ 1 6b So ^ \\\ Bright device 17 Connector 18 Original support 25 Original transport roller 26 Original 27 Platen 28 Feeding the foul path 7 i CIS. Single: Yuan 72 Housing 74 Drive motor 75 Wire 76 Glass plate 77 Press plate 20-