200930670 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種板玻璃之製造方法，詳細而言，本發 明係關於一種利用浮式法成形之板玻璃之製造方法。 【先前技術】 利用浮式法成形來進行板玻璃之製造，係向裝滿於浴槽 中之熔融金屬之表面上連續地供給熔融玻璃，一面藉由穿 過浴槽之頂部而自浴槽内露出之複數個加熱器對上述熔融 玻璃進行加熱，一面使熔融玻璃沿著熔融金屬之表面向特 定方向流動’藉此使具有所期望之寬度及厚度之帶板狀玻 璃帶成形而獲得板玻璃。利用浮式法成形，可使生產性較 高且有效提高平坦性，因此被廣泛用於例如建築用板玻璃 或液晶顯示器之玻璃基板之製造等，於先前已提出有旨在 提高品質之提案（例如，參照專利文獻1、2)。 專利文獻1所揭示之利用浮式法成形之板玻璃之製造方 法’係於玻璃帶之行進方向上將設置加熱器之區域劃分成 複數列’且使任兩列之間、於寬度方向上劃分之部位在寬 度方向上相差一個部位以上。 若於寬度方向上相鄰之區塊之加熱器中該等之每單位面 積的發熱量各不相同，則由此，通過兩個區塊之玻螭帶的 部位將在寬度方向上產生溫度差，但藉由使任兩列之間、 於寬度方向上劃分之部位在寬度方向上相差一個部位以 上’可使得上述溫度差得到緩和。其結果將使玻璃帶之厚 度偏差得到降低。 135680.doc 200930670 又，於專利文獻2所揭示之利用浮式法成形之板玻璃之 製造方法中，由於缺陷之一主要原因在於裝滿於浴槽中之 熔融金屬受到氧化而產生之氧化物會附著在玻璃帶上，因BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sheet glass, and more particularly to a method for producing a sheet glass formed by a float method. [Prior Art] The production of sheet glass by float forming is to continuously supply molten glass to the surface of the molten metal filled in the bath, and to expose the plurality of molten glass from the bath by passing through the top of the bath. Each of the heaters heats the molten glass and flows the molten glass in a specific direction along the surface of the molten metal. Thus, a strip-shaped glass ribbon having a desired width and thickness is molded to obtain a sheet glass. The use of the floating method can improve the productivity and improve the flatness. Therefore, it is widely used for the manufacture of glass substrates such as architectural sheet glass or liquid crystal displays, and has been proposed to improve quality. For example, refer to Patent Documents 1 and 2). The manufacturing method of the sheet glass formed by the floating method disclosed in Patent Document 1 is to divide the region in which the heater is disposed into a plurality of columns in the traveling direction of the glass ribbon and divide the width between the two columns. The parts differ by more than one location in the width direction. If the amount of heat generated per unit area of the heaters adjacent to each other in the width direction is different, the temperature difference in the width direction will be generated by the portion of the glass ribbon passing through the two blocks. However, the temperature difference can be alleviated by making the portion divided between the two columns and the width direction different by one or more portions in the width direction. As a result, the thickness deviation of the glass ribbon is reduced. 135680.doc 200930670 Further, in the method for producing a sheet glass formed by the floating method disclosed in Patent Document 2, one of the defects is mainly because the oxide which is formed by oxidation of the molten metal filled in the bath adheres. On the glass ribbon, because
此將浴槽内間隔成被玻璃帶所覆蓋之空間A與除該空間A 以外之空間B，使惰性氣體流入至空間a以抑制玻璃帶之 變質，並且使還原性氣體流入至空間B以抑制熔融金屬之 氧化。 專利文獻1:日本專利特開平8_325〇24號公報 ❺ 專利文獻2 :日本專利特開平11 -2 113 7號公報 【發明内容】 發明所欲解決之問題 近年來，隨著顯示器之大型化，對顯示品質提出了更高 更穩定之要求，從而對用於上述顯示器令之玻璃基板要求 進一步平坦化並且抑制缺陷。 特別係作為液晶顯示器用玻璃基板之無鹼玻璃，由於其 Q 黏性尚於通常之鈉鈣矽玻璃（Soda-Lime-Silica Glass)，浮 式法成形溫度高達100t以上，且板厚較薄（〇3〜〇7 mm)， 因此進行浮式法成形時難以實現板玻璃之平坦化及缺陷之 抑制。並且，液晶顯示器用玻璃基板於成形後會對表面進 行研磨，但是成形步驟中之平坦度及缺陷會影響研磨量， 從而衫響到生產性及成本。以往，為了實現玻璃帶之平坦 化，係在冷槽内之各部適當調節加熱器輸出，此時，若將 局部的加熱器輸出設定得較低，則存在該部之浴槽内之溫 度降低、玻璃之缺陷增加的問題，從而難以同時實現板玻 135680.doc 200930670 璃之平坦化及缺陷之抑制。又，當於不會產生細微缺陷之 問題時、或者藉由生產條件而難以產生缺陷時，進一步要 求平坦化之情形時，僅將局部的加熱器輸出設定得較低， 將難以獲得所期望之平坦度。 - 本發明係鑒於上述課題研製而成者，目的在於提供一種 平坦性優良且缺陷較少之板玻璃之製造方法。 解決問題之技術手段 上述目的可藉由本發明之下述⑴〜(5)之板玻璃之製造方 好法而達成。 (1)一種板玻璃之製造方法，其特徵在於， 向裝滿於浴槽中之溶融金屬之表面上連績地供給熔融玻 璃’-面藉由穿過上述浴槽之頂部而自上述浴槽内露出之 複數個加熱器對上述熔融玻璃進行加熱，一面使上述溶融 玻璃沿著上述炫融金屬之表面向特定方向流動，藉此使上 述熔融玻璃以浮式法而成形為帶板狀之破璃帶， 〇 上述浴槽具有使上述玻璃帶成形為特定板厚之成形區 域、以及成形後進行緩冷之緩冷區域， • 根據上述溶融玻璃之黏度分布，於上述熔融玻璃之流動 方向上，將上述玻璃帶之成形區域劃分為上游列、中游列 及下游列，且至少於上游列及下游列中，於上述玻璃帶之 寬度方向上劃分為中央部與兩側部， 於上述熔融玻璃之流動穩定之狀態下，將上述玻璃帶之 成形區域之上游列之中央部之區塊以及下游列之中央部之 區塊之加熱器的輸出設為1 KW/m2以下，並且對應於上述 135680.doc 200930670 玻璃帶之成形區域之區塊而將上述頂部之上方空間間隔 開，且對自上方空間之區域流入至上述浴槽内的每單位面 積之氣體流量，相對於其兩侧部之區域之每單位面積之氣 體流量而進行控制’上述上方空間之區域係定義為與上述 上游列之中央部或者上述下游列之中央部中的至少任一方 之區塊相對應者。 ΟThis divides the inside of the bath into a space A covered by the glass ribbon and a space B other than the space A, so that the inert gas flows into the space a to suppress the deterioration of the glass ribbon, and the reducing gas flows into the space B to suppress the melting. Oxidation of metals. [Patent Document 1] Japanese Patent Laid-Open Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. The display quality presents a higher and more stable requirement, thereby requiring further planarization of the glass substrate used for the above display and suppressing defects. In particular, it is an alkali-free glass for a glass substrate for liquid crystal displays. Since its Q viscosity is still in the usual Soda-Lime-Silica Glass, the floating forming temperature is as high as 100 t or more, and the thickness is thin ( 〇3 to 〇7 mm), it is difficult to achieve flattening of the sheet glass and suppression of defects during the float molding. Further, the glass substrate for a liquid crystal display is polished after the surface is formed, but the flatness and defects in the forming step affect the amount of polishing, so that the shirt can be produced with productivity and cost. Conventionally, in order to achieve flattening of the glass ribbon, the heater output is appropriately adjusted in each portion of the cold bath. In this case, if the local heater output is set to be low, the temperature in the bath in the portion is lowered, and the glass is lowered. The problem of increased defects makes it difficult to simultaneously achieve the flattening of the glass and the suppression of defects. Further, when the problem of the fine defect is not generated or the defect is difficult to be produced by the production conditions, when the planarization is further required, only the partial heater output is set low, and it is difficult to obtain the desired one. flatness. The present invention has been made in view of the above problems, and an object of the invention is to provide a method for producing a sheet glass which is excellent in flatness and has few defects. Means for Solving the Problems The above object can be attained by the method for producing the sheet glass of the following (1) to (5) of the present invention. (1) A method for producing a sheet glass, characterized in that a molten glass '-surface is supplied to a surface of a molten metal filled in a bath through a top portion of the bath to be exposed from the bath The plurality of heaters heat the molten glass, and the molten glass flows in a specific direction along the surface of the molten metal, whereby the molten glass is formed into a strip-shaped glass ribbon by a floating method. The bath has a molding region in which the glass ribbon is formed into a specific thickness, and a slow cooling region in which the glass ribbon is slowly cooled after molding. The glass ribbon is formed in the flow direction of the molten glass according to the viscosity distribution of the molten glass. The forming region is divided into an upstream row, a middle row, and a downstream row, and is divided into a central portion and both side portions in the width direction of the glass ribbon at least in the upstream row and the downstream row, and the flow of the molten glass is stabilized. Next, the output of the heater at the central portion of the upstream row of the forming region of the glass ribbon and the heater at the central portion of the downstream row a space above 1 KW/m2 and corresponding to the block of the forming area of the above 135680.doc 200930670 glass ribbon, and the space above the top portion is spaced apart, and the area per unit area from the upper space flows into the bath The gas flow rate is controlled with respect to the gas flow rate per unit area of the regions on both sides thereof. The region of the upper space is defined as at least one of the central portion of the upstream column or the central portion of the downstream column. Block counterparts. Ο
(2)如上述（丨）所揭示之板玻璃之製造方法，其中將自上 方空間之區域流入至上述浴槽内之每單位面積之氣體流 量’相對於其兩側部之區域之每單位面積之氣體流量控制 為，以上〜未滿嶋’上述上方空間之區域係與上述玻 璃絜之成％區域之上述上游列 < 中央#或者上述下游列之 中央部中的至少任一方之區塊相對應者。 (3) 如上述（1)所揭示之板玻璃之製造方法，其中將自上 方空間之區域流入至上述浴槽内之每單位面積之氣體流 量’相對於其兩侧部之區域之每單位面積之氣體流量控制 為超過100%且小於等於2〇〇%，上述上方空間之區域係與 上述玻璃帶之成形區域之上述上游列之中央部或者上述下 游列之中央部中的至少任一方之區塊相對應者。 (4) 如上述（1)〜(3)中任一項所揭示之板玻璃之製造方 法，其中上述玻璃帶之成形區域之上游列中，上述熔融玻 璃之黏度分布為1〇^〜105.3泊，該上游列中之中央部與兩 側部，係在自玻璃引導器之出口寬度之端朝向中央之方向 上，分別於0〜450 mm之處劃分而成，上述玻璃引導器設 置於上述熔融玻璃之供給部，以將上述熔融玻璃之流動導 135680.doc 200930670 向上述特定方向， 上述玻璃帶之成形區域之下游列中’上述熔融玻璃之黏 度分布為1〇5·7〜107.5泊，該下游列中之中央部與兩側部， 係於玻璃帶之中央部之寬度相對於兩側邊之間之寬度為 20〜40%之處劃分而成。 (5)如上述（4)所述之板玻璃之製造方法，其中於上述玻 璃帶之成形區域之中游列中，將自下游列側之端部起算朝 向上游列側距離4000〜5000 mm之區域劃分為中游後段 列’且於玻璃帶之中央部之寬度相對於兩側邊之間之寬度 為20〜40%之處，將該中游後段列劃分為中.央部與兩側 部， 於上述熔融玻璃之流動穩定之狀態下，使上述玻璃帶之 成形區域之中游後段列之中央部之區塊的加熱器之每單位 面積的輸出，與兩側部之區塊之加熱器之每單位面積之輸 出相比為50%以下。 發明之效果 本發明係於浮式浴槽中之熔融玻璃之流動穩定之狀態 下，中斷玻璃帶之成形區域的上游列之中央部之區塊以及 下游列之中央部的區塊之加熱器之輸出而進行生產，藉此 可使玻璃帶之寬度方向之厚度均勻化。此外，對自上方空 間之區域流入至浴槽内的每單位面積之氣體流量，相對於 其兩侧部之區域之每單位面積之氣體流量而加以控制來進 行生產，上述上方空間之區域係與玻璃帶之成形區域之上 游列的中央部或者下游列之中央部中的至少任—方之區塊 135680.doc -10- 200930670 相對應者，藉此可防止兩區塊中之浴槽内之環境溫度過度 降低’從而抑制浴槽内之熔融金屬蒸汽產生凝聚以及該凝 聚物落在玻璃帶上。又，於不會產生細微缺陷之問題時、 或者轉由生產條件而難以產生缺陷時，亦可實現進一步之 平坦化。藉此，可獲得平坦性優良且缺陷較少之板玻璃。 【實施方式】 以下，參照圖式，詳細說明本發明之板玻璃之製造方法 之一實施形態。 圖1係表示實施本發明之板玻璃之製造方法之裝置之一 例的剖面圖，圖2係圖1中之IMI線之剖面圖，圖3係圖2中 之III-III線之剖面圖’圖4係圖1中之IV_IV線之剖面圖。 如圖1所示，於浮法設備之浴槽丨中裝滿有熔融金屬2， 一面藉由爐閘門（tweel)15來控制熔融玻璃3之流量，一面 自澆斗嘴（lip)16向熔融金屬2之表面上連續地供給該熔融 玻璃3。典型的熔融金屬2係錫。 進而參照圖2，藉由玻璃引導器19而對供給至熔融金屬2 之表面上之熔融玻璃3加以引導，使其自圖中之左側向右 側流動。玻璃引導器19例如由一對障壁所構成，該等一對 障壁豎立設置於浴槽1之底壁上，於位於澆斗嘴16下方之 熔融玻璃3之供給部自熔融金屬2的表面露出，且該等一對 障壁係朝向熔融玻璃3之流動方向而配置。 熔融玻璃3藉由自浴槽1内露出之複數個加熱器丨丨而加熱 後’向上述特定方向流動而形成帶板狀之玻璃帶4。將玻 璃帶4自浴槽1之出口 12取出，其後，藉由未圖示之層面 135680.doc 200930670 (hyer)(緩冷爐）而加以緩冷並於洗淨後切割為特定之尺 寸。 冷槽1之頂部構造6具有由磚壁所構成且配置於熔融金屬 2之上方之頂部壁7、以及自上方覆蓋頂部壁7之罩殻 (CaSlng)8。對熔融玻璃3進行加熱之複數個加熱器u適當 分布於玻璃帶4之成形區域F1及緩冷區域F2，且分別使其 發熱部穿過頂部壁7而自浴槽丨内露出而配置。 於罩殻8中設置供氣管1〇，以向頂部壁7之上方即頂部壁 7與罩殻8之間之上方空間17供給氣體。頂部壁了上設置有 供各加熱器11插通之貫通孔，供給至頂部壁7之上方空間 之氣體通過該貫通孔中之加熱器i丨與頂部壁7之間隙，而 流入至頂部壁7之下方空間、即浴槽内18。 供給至浴槽内18之氣體以惰性氣體為主要成分，用以防 止熔融玻璃3之變質。再者，亦可含有還原性氣體，以防 止產生熔融金屬2之氧化物，藉此可防止玻璃帶4產生缺 ❹ 陷° 於生產開始時或施工後之生產恢復時等的啟動（stan up) 時，典型的做法係將玻璃帶4之溫度整體設定得較高，繼 而使熔融玻璃3自成形區域F丨順暢地向緩冷區域F2流動。 ' 此處，所謂啟動時，係指自浴槽1之出口 12抽出之玻璃帶4 之量（ton/小時）之不均超過5〇/。的狀態。 於熔融玻璃3之流動穩定之狀態下，在位於熔融玻璃3之 供給部之附近的玻璃帶4之成形區域？1的上游側，存在玻 璃帶寬度方向中央部之熔融玻璃3不向周圍蔓延而易於堆 135680.doc -12- 200930670 積，導致玻璃帶4之中央部之厚度增大之傾向。又，於玻 璃帶4之成形區域F1之下游側，存在玻璃帶4之侧邊部分之 厚度增大之傾向。此處，所謂穩定狀態，係指自浴槽出口 所抽出之玻璃帶4之量（ton/小時）之不均為5%以内的狀態。 因此，如圖2所示，根據熔融玻璃3之黏度分布，於熔融 玻璃3之流動方向上，將玻璃帶4之成形區域F1劃分為上游 列、中游列及下游列（分別為a列、b列及c列此三列），且至 少於a、c列中在玻璃帶4之寬度方向上劃分為中央部（Η、 〇 c 1)與兩側部（a2、a3、c2、c3)。 本實施形態中，玻璃帶4之成形區域F丨之上游列a列中， 熔融玻璃之黏度分布為i扑8〜〗〇5·3泊（無鹼玻璃之情形時相 當於1120〜1300°C，鹼石灰玻璃之情形時相當於895〜1〇7〇 C )，且a列中之中央部與兩側部，係在自玻璃引導器19之 出口寬度w之端朝向中央之方向上分別於〇〜45〇 mm、較好 的是0〜300 mm、更好的是150〜25〇爪爪之處劃分而成。 〇 又，於本實施形態中 ’玻璃帶4之成形區域fi之下游列£； 列中，熔融玻璃3之黏度分布為1〇”〜1〇7.5泊（無鹼玻璃之 情形時相當於945〜1〇80。(：，鹼石灰玻璃之情形時相當於 740〜860°C) ’且〇列中之中央部與兩側部，係於玻璃帶之 中央部之寬度相對於兩側邊之間之寬度為2〇〜4〇%之處劃 分而成。 並且，於溶融玻璃3之流動穩定之狀態下，將a列之中央 部之區塊al以及c列之中央部之區塊cl之每單位面積之加 熱器11的輸出設為1 Kw/m2以下，較好的是設為〇 5 Kw/m2 135680.doc -13· 200930670 以下’更好的是設為0.05 KW/m2以下。進而更好的是中斷 加熱器11之輸出。 區塊al中，因熔融玻璃3之供給部而存在玻璃帶4之厚度 增大之傾向。藉由中斷區塊al之加熱器11之輸出，可使區 塊al之環境溫度降低，使得熔融玻璃3易於有效地向周圍 蔓延，由此可使玻璃帶4之厚度在其寬度方向上均勻化。 又’區塊cl中’玻璃帶4之帶寬易於縮小。藉由中斷區 塊c 1之加熱器11之輸出’可使區晝c 1之環境溫度低於區塊 c2、c3之環境溫度，使得區塊c2、c3之兩側邊的寬度難以 縮小’由此可使玻璃帶4之厚度在其寬度方向上均勻化。 再者，於中游列b列中，亦可將自c列側之端朝向a列側 之方向上4000〜5000 mm之區域劃分為中游後段列（b，列）， 且於該中游後段列中，於玻璃帶4之中央部之寬度相對於 兩側部之間之寬度為20〜40%之處劃分為中央部（b'i)與兩 側部（b'2、b'3)。中游後段列（b’列）中，與c列同樣地存在玻 璃帶4之帶寬易於縮小之傾向，因此較好的是將中游後段 列（b’列）之中央部之區塊b’l之加熱器1丨之每單位面積的輸 出’與兩側部之區畫b’2、b’3之加熱器11之每單位面積之 輸出相比控制為50%以下。更好的是控制為5〜3〇%，進而 更好的是控制為5〜20% ’最好的是抑制為5〜1〇%。藉此， 區塊b，2、b’3之兩側邊之寬度難以縮小，由此可使玻璃帶4 之厚度在其寬度方向上均勻化。 進而，如圖1、圖3以及圖4所示’對應於玻璃帶4之成形 區域F1之區塊al〜a3、cl〜C3而利用間隔板9將頂部壁7之上 135680.doc -14- 200930670 方空間17間隔成區域A1〜A3、C1〜C3，且對朝向至少區域 A1或C1中之任一方之氣體供給量進行控制。於抑制缺陷 之情形時，將自區域八丨及/或^流入至浴槽内18之每單位 面積之氣體流量，設為自其兩側部之區域流入至浴槽】内 之每單位面積之氣體流量的2〇以上〜未滿ι〇〇%。 區塊al以及區塊cl中，於熔融玻璃3之流動穩定之狀態 下中斷加熱器11之輸出，從而使環境溫度降低，若向上述 區塊al以及區塊〇1過度供給氣體，則可能導致環境溫度進 一步降低，浴槽内18之熔融金屬蒸汽產生凝聚而落下並附 者於玻璃帶4之表面。於穩定狀態時，使自頂部壁7之上方 空間17之區域A1及/或區域C1流入至浴槽1内之每單位面積 的氣體流量減少，上述頂部壁7之上方空間17之區域入丨及/ 或區域C1對應於區塊ai及區塊ci，藉此可防止環境溫度之 過度降低，從而防止熔融金屬蒸汽之凝聚。由此，可減少 玻璃帶4之缺陷。 又’當於不會產生細微缺陷之問題時、或者藉由生產條 件而難以產生缺陷時’進一步要求平坦化之情形時，將自 區域A1及/或C1流入至浴槽内18之每單位面積的氣體流 量’設為自其兩側部之區域流入至浴槽1内之每單位面積 之氣體流量的超過1 〇 〇 %〜2 0 0 %。藉此，使玻璃帶4之平坦 性得到提高。 再者’於玻璃帶4之成形區域之中游後段列中抑制中央 部之區塊VI之加熱器11之輸出時，亦可與A1〜A3、C1〜C3 同樣’對應於區塊b，l〜b'3，藉由間隔板9而將頂部壁7之上 135680.doc 15 200930670 方空間17間隔成B’ 1〜B’3，並且相對於自b'2、B，3流入之每 單位面積之氣體流量’而對自區域Βΐ流入至浴槽1内之每 單位面積的氣體流量加以控制（減少或者增加）。 如上所述’供給至浴槽丨内之氣體以惰性氣體為主要成 分，其中亦可含有還原性氣體。例如，供給至玻璃帶4之 成形區域F1之上游列&列的區塊al〜a3之氣體為1〇〇%之氮 虱。又，供給至玻璃帶4之成形區域F1之中游列b列的氣體 為氫氣與氮氣之混合氣體’其中含有丨.5〜1〇%之氫氣。 又’供給至玻璃帶4之成形區域F1中之下游列c列之區塊 cl〜c 3的氣體為氫氣與氮氣之混合氣體，其中含有7. $〜1〇% 之氫氣，較好的是含有8〜9%之氫氣。又，向成形後之玻(2) The method for producing a sheet glass according to the above (丨), wherein a gas flow rate per unit area from a region of the upper space into the bath is relative to a unit area of a region of both sides thereof The gas flow rate is controlled such that the area of the upper space above is less than the block of at least one of the upstream column < central # or the central portion of the downstream row in the % region of the glass crucible By. (3) The method for producing a sheet glass according to the above (1), wherein a gas flow rate per unit area from a region of the upper space into the bath is relative to a unit area of a region of both sides thereof The gas flow rate is controlled to be more than 100% and less than or equal to 2% by weight, and the area of the upper space is at least one of a central portion of the upstream row or a central portion of the downstream row of the molding region of the glass ribbon. Corresponding. (4) The method for producing a sheet glass according to any one of the above (1) to (3) wherein, in the upstream row of the forming region of the glass ribbon, the viscosity distribution of the molten glass is 1 〇 ^ 10 10 5.3 poise The central portion and the both side portions of the upstream row are defined at a position from the end of the width of the outlet of the glass guide toward the center, respectively, at 0 to 450 mm, and the glass guide is disposed in the above-mentioned melting The supply portion of the glass is such that the flow guide of the molten glass is 135680.doc 200930670 in the specific direction, and the viscosity distribution of the molten glass in the downstream row of the formed region of the glass ribbon is 1〇5·7 to 107.5 poise. The central portion and the both side portions of the downstream row are defined by the width of the central portion of the glass ribbon being 20 to 40% of the width between the two sides. (5) The method for producing a sheet glass according to the above aspect (4), wherein the end portion of the downstream side of the glass ribbon is in a range of from 4000 to 5000 mm from the end portion on the downstream side. Divided into the middle segment of the middle segment and where the width of the central portion of the glass ribbon is 20 to 40% with respect to the width between the two sides, the middle segment of the middle segment is divided into the central portion and the two sides, In a state in which the flow of the molten glass is stabilized, the output per unit area of the heater of the block in the central portion of the rear row of the formed zone of the glass ribbon and the heater per unit area of the block on both sides are made. The output is 50% or less. Advantageous Effects of Invention According to the present invention, in the state where the flow of the molten glass in the floating bath is stabilized, the output of the block at the central portion of the upstream row of the forming region of the glass ribbon and the heater at the central portion of the downstream row are interrupted. Production is carried out, whereby the thickness of the glass ribbon in the width direction is made uniform. Further, the flow rate of the gas per unit area flowing into the bath from the area of the upper space is controlled by controlling the gas flow rate per unit area of the area between the both sides, and the area of the upper space is the glass. At least one of the central portion of the upstream row of the belt forming zone or the central portion of the downstream row corresponds to the block 135680.doc -10- 200930670, thereby preventing the ambient temperature in the bath in the two blocks Excessively lowering' thereby inhibiting the condensation of molten metal vapor in the bath and the agglomerate falling on the glass ribbon. Further, even when the problem of fine defects does not occur or when it is difficult to generate defects by the production conditions, further flattening can be achieved. Thereby, a plate glass excellent in flatness and less in defects can be obtained. [Embodiment] Hereinafter, an embodiment of a method for producing a sheet glass of the present invention will be described in detail with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing an example of an apparatus for manufacturing a sheet glass of the present invention, Fig. 2 is a cross-sectional view taken along line IMI of Fig. 1, and Fig. 3 is a sectional view taken along line III-III of Fig. 2. 4 is a cross-sectional view taken along line IV_IV of Fig. 1. As shown in Fig. 1, the bath tank of the float apparatus is filled with molten metal 2, and the flow rate of the molten glass 3 is controlled by a tweel 15, while the molten metal is transferred from the pour 16 to the molten metal 2 The molten glass 3 is continuously supplied on the surface. A typical molten metal 2 is tin. Further, referring to Fig. 2, the molten glass 3 supplied onto the surface of the molten metal 2 is guided by the glass guide 19 to flow to the right from the left side in the drawing. The glass guide 19 is constituted, for example, by a pair of barrier ribs which are erected on the bottom wall of the bathtub 1 and are exposed from the surface of the molten metal 2 at the supply portion of the molten glass 3 located below the spout nozzle 16, and A pair of barrier ribs are disposed toward the flow direction of the molten glass 3 . The molten glass 3 is heated by a plurality of heaters exposed from the inside of the bath 1, and then flows in the specific direction to form a strip-shaped glass ribbon 4. The glass ribbon 4 is taken out from the outlet 12 of the bath 1, and then slowly cooled by a layer 135680.doc 200930670 (hyer) (not shown) and cut into a specific size after washing. The top structure 6 of the cold trough 1 has a top wall 7 composed of a brick wall and disposed above the molten metal 2, and a casing (CaSlng) 8 covering the top wall 7 from above. The plurality of heaters u for heating the molten glass 3 are appropriately distributed in the forming region F1 and the slow cooling region F2 of the glass ribbon 4, and the heat generating portions are respectively disposed through the top wall 7 and exposed from the bathing chamber. An air supply pipe 1 is provided in the casing 8 to supply gas to the upper space 17 above the top wall 7, that is, between the top wall 7 and the casing 8. The top wall is provided with a through hole through which the heaters 11 are inserted, and the gas supplied to the space above the top wall 7 passes through the gap between the heater i 丨 and the top wall 7 in the through hole, and flows into the top wall 7 The space below, that is, the inside of the bath 18. The gas supplied to the bath 18 is mainly composed of an inert gas to prevent deterioration of the molten glass 3. Further, a reducing gas may be contained to prevent generation of an oxide of the molten metal 2, thereby preventing the glass ribbon 4 from being defective. Stan up at the start of production or after production recovery after construction (stan up) In the typical case, the temperature of the glass ribbon 4 is set to be high as a whole, and then the molten glass 3 is smoothly flowed from the forming region F to the slow cooling region F2. Here, the term "starting" means that the amount of the glass ribbon 4 (ton/hour) extracted from the outlet 12 of the bath 1 is less than 5 〇. status. In the state where the flow of the molten glass 3 is stable, in the forming region of the glass ribbon 4 located in the vicinity of the supply portion of the molten glass 3? On the upstream side of the first side, the molten glass 3 in the center portion in the width direction of the glass ribbon does not spread to the periphery and is easy to pile up, resulting in an increase in the thickness of the central portion of the glass ribbon 4. Further, on the downstream side of the forming region F1 of the glass ribbon 4, the thickness of the side portion of the glass ribbon 4 tends to increase. Here, the steady state means a state in which the amount (ton/hour) of the glass ribbon 4 taken out from the outlet of the bath is not within 5%. Therefore, as shown in FIG. 2, according to the viscosity distribution of the molten glass 3, the forming region F1 of the glass ribbon 4 is divided into an upstream column, a middle row, and a downstream column in the flow direction of the molten glass 3 (a column, b, respectively) The column and the c column are the three columns, and are divided into a central portion (Η, 〇c 1) and both side portions (a2, a3, c2, and c3) in the width direction of the glass ribbon 4 at least in the columns a and c. In the present embodiment, in the upstream row a of the forming region F of the glass ribbon 4, the viscosity distribution of the molten glass is i to 8 to 〇5·3 poise (in the case of alkali-free glass, it is equivalent to 1120 to 1300 °C). In the case of soda lime glass, it corresponds to 895~1〇7〇C), and the central portion and the both side portions in the row a are respectively in the direction from the end of the outlet width w of the glass guide 19 toward the center. 〇~45〇mm, preferably 0~300mm, more preferably 150~25〇 claws are divided. Further, in the present embodiment, the downstream of the forming region fi of the glass ribbon 4 is listed; in the column, the viscosity distribution of the molten glass 3 is 1 〇" to 1 〇 7.5 poise (in the case of an alkali-free glass, it corresponds to 945~) 1〇80. (:, in the case of soda lime glass, it is equivalent to 740~860 °C) 'and the central part and the two sides of the sill line are between the width of the central part of the glass ribbon and the sides In the state where the flow of the molten glass 3 is stable, the block a1 at the central portion of the a column and the block cl at the central portion of the c column are each divided. The output of the heater 11 per unit area is set to 1 Kw/m2 or less, preferably 〇5 Kw/m2 135680.doc -13·200930670 or less. More preferably, it is set to 0.05 KW/m2 or less. Preferably, the output of the heater 11 is interrupted. In the block a1, the thickness of the glass ribbon 4 tends to increase due to the supply portion of the molten glass 3. By interrupting the output of the heater 11 of the block a1, the region can be made. The ambient temperature of the block a1 is lowered, so that the molten glass 3 is easily and effectively spread to the surroundings, whereby the thickness of the glass ribbon 4 can be made The bandwidth of the glass ribbon 4 is easily reduced in the 'block cl'. By interrupting the output of the heater 11 of the block c1, the ambient temperature of the zone c1 is lower than the block c2. The ambient temperature of c3 makes it difficult to reduce the width of the sides of the blocks c2 and c3. Thus, the thickness of the glass ribbon 4 can be made uniform in the width direction. Further, in the middle row b column, The area from the end of the c-column side toward the a-column side in the direction of 4000 to 5000 mm is divided into the middle-back rear-end row (b, column), and in the middle-middle rear-end row, the width of the central portion of the glass ribbon 4 is opposite to the two The width between the side portions is 20 to 40%, and is divided into a central portion (b'i) and both side portions (b'2, b'3). The midstream rear segment (b'column) is the same as the c column. In the ground, there is a tendency that the bandwidth of the glass ribbon 4 is easy to be reduced. Therefore, it is preferable to output the 'area per unit area' of the heater 1' of the block b'1 in the central portion of the mid-stream rear row (b'column) The output per unit area of the heaters 11 of the districts b'2 and b'3 is controlled to be 50% or less. More preferably, the control is 5 to 3%, and further Preferably, the control is 5 to 20%. The best suppression is 5 to 1%. Thereby, the widths of the sides of the blocks b, 2, and b'3 are difficult to be reduced, thereby making the glass ribbon 4 The thickness is uniformized in the width direction thereof. Further, as shown in Figs. 1, 3, and 4, the partitions 9 are used to correspond to the blocks a1 to a3, cl to C3 of the forming region F1 of the glass ribbon 4. Above the wall 7, 135680.doc -14- 200930670, the square space 17 is partitioned into areas A1 to A3, C1 to C3, and the amount of gas supplied toward at least one of the areas A1 or C1 is controlled. In the case of suppressing the defect, the gas flow rate per unit area from the area gossip and/or into the bath 18 is set as the gas flow per unit area flowing into the bath from the area of the both sides thereof. 2〇 or more~Unfilled 〇〇〇〇%. In the block a1 and the block cl, the output of the heater 11 is interrupted in a state where the flow of the molten glass 3 is stabilized, so that the ambient temperature is lowered, and if the gas is excessively supplied to the block a1 and the block 〇1, it may result in The ambient temperature is further lowered, and the molten metal vapor in the bath 18 is agglomerated to fall and attached to the surface of the glass ribbon 4. In the steady state, the flow rate of gas per unit area flowing into the bath 1 from the area A1 and/or the area C1 of the space 17 above the top wall 7 is reduced, and the area of the space 17 above the top wall 7 is in/out. Or the region C1 corresponds to the block ai and the block ci, whereby an excessive decrease in the ambient temperature can be prevented, thereby preventing aggregation of the molten metal vapor. Thereby, the defects of the glass ribbon 4 can be reduced. Further, when the problem of fine defects is not caused, or when it is difficult to generate defects by production conditions, when the flattening is further required, the area A1 and/or C1 flows into the bath unit 18 per unit area. The gas flow rate is set to be more than 1% to 200% of the gas flow rate per unit area flowing into the bath 1 from the both side portions. Thereby, the flatness of the glass ribbon 4 is improved. Further, when the output of the heater 11 of the block VI at the center portion is suppressed in the rear row of the glass ribbon 4, the same as A1 to A3, C1 to C3, and the block b, l~ B'3, the 135680.doc 15 200930670 square space 17 above the top wall 7 is partitioned into B' 1~B'3 by the partition plate 9, and per unit area with respect to the inflow from b'2, B, 3 The gas flow rate 'controls (reduces or increases) the gas flow per unit area flowing from the zone 至 into the bath 1 . As described above, the gas supplied to the bath tank contains an inert gas as a main component, and may also contain a reducing gas. For example, the gas supplied to the blocks a1 to a3 of the upstream column & column of the forming region F1 of the glass ribbon 4 is 1% by nitrogen. Further, the gas supplied to the row B of the molding region F1 of the glass ribbon 4 is a mixed gas of hydrogen and nitrogen, which contains 丨5 to 1% of hydrogen. Further, the gas supplied to the blocks cl to c3 of the downstream column c in the forming region F1 of the glass ribbon 4 is a mixed gas of hydrogen and nitrogen, and contains 7. 〜1〇% of hydrogen, preferably Contains 8 to 9% hydrogen. Again, to the glass after forming
璃帶4之緩冷區域F2，供給含有7 5〜1〇%之氫氣之氫氣與氮 氣之混合氣體D 進而’當緩冷後之玻璃帶4之寬度方向之板厚存在局部 偏差時’較好的是’於中游列（b列）中，將自中游後段列 (b列）之上游端朝向上游列（&列）側之方向上45〇〇〜6〇〇〇 之區域劃分為中游中段列（bu列）（未圖示），並根據緩冷後 之玻璃帶4之寬度方向的板厚偏差，對中游中段列（1)，，列）之 寬度方向之加熱器Η的輸出進行控制。 具體而言’較好的是以如下方式進行控制。 0)使自洛槽1之出口丨2抽出之玻璃帶4於未圖示之緩冷爐中 緩冷後’以20 mm之間距來測定玻璃帶4之寬度方向（自玻 璃帶4之兩側邊分別除去400 mm之範圍）的板厚。 (2)將在任意500 mm間相對於平均板厚之板厚偏差均為】〇 1356S0.doc -16 - 200930670 ㈣以上之部位作為對象，以增加相當於大於平均板厚之 部位的加熱ιιη之輸出，且減少相當於小於平均板厚之部 位的加熱器11之輸出的方式來進行控制。 (3) 加熱器U之輸出之增減量係根據板厚偏差來設定。例 如，若板厚偏差為’ μιη以上，則將每單位面積之加熱器 11之輸出增加5〜35%、較好的是增加5〜25%，若板厚偏差 為10 μηι以上，則將每單位面積之加熱器丨丨之輸出減少 5〜35%、較好的是減少5〜25%。 (4) 上述控制可根據板厚測定結果而自動進行，亦可手動進 行。 實施例 以下’對本發明之板玻璃之製造方法之實施例加以說 明。表1表示各實施例1〜實施例4中，熔融玻璃之流動穩定 之狀態下玻璃帶之成形區域之上游列、中游後段列、下游 列之中央部之各區塊（a 1、b，1、c 1)及兩侧部之各區塊（a2、 ❹ a3、b’2、b'3、e2、c3)之每單位面積的加熱器輸出、以及 自上方空間之各區域（Al、、C1)及上方空間之各區域 (A2、A3、B’2、B，3、C2、C3)流入至浴槽内之每單位面積 的氣體流量，其中上述上方空間之各區域（A1、B，1、C1) 對應於上游列、中游後段列、下游列之中央部之各區塊， 上述上方空間之各區域（A2、A3、B，2、B，3、C2、C3)對應 於上游列、中游後段列、下游列之兩側部之各區塊。 實施例1以及實施例4係一方面確保玻璃帶之平坦性、一 方面抑制缺陷之情形的示例。於該實施例1中，中斷上游 135680.doc • 17· 200930670 列之中央部之區塊（al)以及下游列之中央部之區塊（cl)之 加熱器輸出，並使中游後段列之中央部之區塊（b· 1)之每單 位面積之加熱器輸出，達到其兩侧部之區塊（b'2、b'3)之每 單位面積之加熱器輸出的50%以下。並且，使自與上游列 之中央部之區塊對應之上方空間之區域（A1)流入至浴槽内 的每單位面積之氣體流量、與自其兩側部之區域（A2、A3) 流入至浴槽内之每單位面積的氣體流量均等，且使自上方 空間之各區域（B'l、C1)流入至浴槽内之每單位面積之氣體 流量、減少至小於自其兩側部之區域（B，2、B'3、C2、C3) 流入至浴槽内之每單位面積的氣體流量，上述上方空間之 各區域（Β· 1、C1)對應於中游後段列之中央部之區塊及下游 列之甲央部之區塊。 實施例2係於不太會產生缺陷問題時進一步要求平坦性 之情形時的示例。於該實施例2中，中斷上游列之中央部 之區塊（al)及下游列之中央部之區塊（cl)之加熱器輸出， 並使中游後段列之中央部之區塊（1νι)之每單位面積之加熱 器輸出’達到其兩側部之區塊（b，2、b,3)之每單位面積之加 熱器輸出的50〇/〇以下。並且，使自上方空間之各區域 (Al、C1)流入至浴槽内之每單位面積之氣體流量，增加至 大於自其兩侧部之區域(A2、A3、C2、C3)流入至浴槽内 的每單位面積之氣體流量，上述上方空間之各區域⑷、 C1)對應於上游列之中央部之區塊及下游列之中央部之區 塊，且使自上方空間之區域㈣流人至浴槽内的每單位面 積之氣體流量’減少至小於自其兩側部之區域⑽、叫 135680.doc 200930670 化入至浴槽内之每單位面積的氣體流量，上述上方空間之 區域（B’ 1)對應於中游後段列之中央部之區塊。 實施例3係於會產生缺陷問題時一方面防止缺陷一方面 亦提高平坦性之情形時的示例。於該實施例3令，中斷上 游列之中央部之區塊（al)以及下游列之中央部之區塊（^) 之加熱器輸出，並使中游後段列之中央部之區塊（bli)之每 單位面積之加熱器輸出，達到其兩側部之區塊（b，2、b，3)之 每單位面積之加熱器輸出的5〇%以下。並且，使自上方空 間之各區域（Al、B，l)流入至浴槽内之每單位面積之氣體 流量，減少至小於自其兩側部之區域（A2、A3、B,2、 流入至浴槽内的每單位面積之氣體流量，上述上方空間之 各區域（Al、B，l)對應於上游列之中央部之區塊及中游後 段列之中央部之區塊，且使自上方空間之區域（C1)流入至 浴槽内之每單位面積的氣體流量，増加至大於自其兩侧部 之區域(C2、C3)流入至浴槽内之每單位面積的氣體流量， 上述上方空間之區域（C1)對應於下游列之中央部之區塊。 [表1] 上泳 參列 中游後段列 下游?ΐϊ - 丨· 實施例1 中央部 al 兩側部 a2 > a3 12.3 中央部 b，l — ~~52~~ 兩側却 上2 、 b，3 中央部 cl c2、c3 __253 5 2 0 〇 η 14.9 氣體流量Nm3/h · m2 3.2 3.2 3.2~~ 實施例2 加熱器輸出ΚΛν/m2 0 10.3 5.0 1_21.9 0 2.9 1 -, 12.7 氣體流量Nm3/h · m2 5.3 2.9 3.2~~ 4 0 9 7 實施例3 加熱器輸出KW/m2 氣體流量Nm3/lrm2 0 12.0 ~Ϊ5~ 6.5 ----- 6 0 Ζ· / 8.9 2.5 — _ 11.4 實施例4 加熱器輸出KWmz 0 11.8 5.1 ν*\/ 22 0 0 13T~ 氣體流量Nm3/h · m2 2.1 2.1 3.2 6 Q 2.7 9.2 — .. 135680.doc -19- 200930670 於實施例1〜4之條件下，進行無驗玻璃之玻璃帶之成 形。其結果為’可獲得平坦性優良且缺陷較少之板玻璃作 為液晶顯示器用玻璃基板。 如上所述’根據本實施形態之板玻璃之製造方法，於溶 融玻璃3之流動穩定的狀態下，中斷玻璃帶4之成形區域F1 之上游列a列的中央部之區塊al以及下游列c列之中央部的 區塊cl之加熱器11之輸出’藉此可容易地使玻璃帶*之厚 度在其寬度方向上均勻化。 ❹ 進而，使自頂部壁7之上方空間之區域Al、C1流入至浴 槽1内的每單位面積之氣體流量，減少至小於其兩側部之 區域之每單位面積的氣體流量，上述頂部壁7之上方空間 之區域Al、C1係與玻璃帶4之成形區域F1之上游列3列的 中央部之區塊al及/或下游列c列之中央部的區塊c丨相對 應，藉此可防止兩區塊al、cl中之環境溫度過度降低，從 而抑制浴槽内18之熔融金屬蒸汽產生凝聚，防止凝聚物落 〇 纟玻璃帶表面。藉此，可穩定地生產平坦性優良且缺陷較 少之板玻璃。The slow cooling zone F2 of the ribbon 4 supplies a mixed gas of hydrogen and nitrogen containing 7 5 to 1% of hydrogen, and further 'when there is a local deviation in the thickness direction of the glass ribbon 4 after the slow cooling, 'good. In the middle row (column b), the area from the upstream end of the middle row of the middle row (column b) to the upstream column (&column) side is divided into the middle middle segment. Column (bu column) (not shown), and controlling the output of the heater 宽度 in the width direction of the midstream middle row (1), column) according to the thickness deviation in the width direction of the glass ribbon 4 after the slow cooling . Specifically, it is preferable to control in the following manner. 0) After the glass ribbon 4 taken out from the outlet 丨2 of the Luo tank 1 is slowly cooled in a slow cooling furnace (not shown), the width direction of the glass ribbon 4 is measured at a distance of 20 mm (from both sides of the glass ribbon 4) The thickness of the range of 400 mm is removed separately. (2) The deviation of the plate thickness relative to the average plate thickness between any 500 mm is 〇1356S0.doc -16 - 200930670 (4) The above part is used as the object to increase the heating equivalent of the part larger than the average thickness. The output is controlled to reduce the output of the heater 11 corresponding to a portion smaller than the average thickness. (3) The increase or decrease of the output of the heater U is set according to the thickness deviation. For example, if the sheet thickness deviation is 'μιη or more, the output of the heater 11 per unit area is increased by 5 to 35%, preferably by 5 to 25%, and if the sheet thickness deviation is 10 μη or more, each will be The output per unit area of the heater is reduced by 5 to 35%, preferably by 5 to 25%. (4) The above control can be performed automatically based on the thickness measurement result or manually. EXAMPLES Hereinafter, examples of the method for producing the sheet glass of the present invention will be described. Table 1 shows the respective blocks (a 1, b, 1 in the upstream row, the mid-stream rear row, and the downstream column) in the forming region of the glass ribbon in the state in which the flow of the molten glass is stabilized in each of Examples 1 to 4. , c 1) and the heater output per unit area of each block (a2, ❹ a3, b'2, b'3, e2, c3) on both sides, and the area from the upper space (Al, C1) and each area of the upper space (A2, A3, B'2, B, 3, C2, C3) flows into the bath per unit area of gas flow, wherein each area of the above space (A1, B, 1) And C1) corresponding to each block of the central portion of the upstream column, the middle segment, and the downstream column, and the regions (A2, A3, B, 2, B, 3, C2, and C3) of the upper space correspond to the upstream column, The blocks in the back row of the middle row and the two sides of the downstream column. The first embodiment and the fourth embodiment are examples in which the flatness of the glass ribbon is ensured and the defect is suppressed in one aspect. In the first embodiment, the heater output of the block (al) of the central portion of the upstream 135680.doc • 17·200930670 column and the block (cl) of the central portion of the downstream column is interrupted, and the center of the middle segment of the middle row is interrupted. The heater output per unit area of the block (b·1) reaches 50% or less of the heater output per unit area of the blocks (b'2, b'3) on both sides. Further, the flow rate of the gas per unit area flowing into the bath from the region (A1) in the upper space corresponding to the block in the central portion of the upstream row, and the region (A2, A3) from both sides thereof flow into the bath. The gas flow rate per unit area is equal, and the gas flow per unit area flowing into the bath from each region (B'1, C1) of the upper space is reduced to be smaller than the area from both sides (B, 2, B'3, C2, C3) The flow rate of gas per unit area flowing into the bath, the areas of the above upper space (Β·1, C1) correspond to the block and the downstream column of the central part of the middle row of the middle reaches Block of the Central Department. Embodiment 2 is an example in the case where the flatness is further required when the defect problem is less likely to occur. In the second embodiment, the heater output of the block (cl) at the central portion of the upstream column and the block (cl) at the central portion of the downstream column is interrupted, and the block at the central portion of the middle row of the middle row is interrupted (1 νι) The heater output per unit area reaches 50 〇/〇 of the heater output per unit area of the blocks (b, 2, b, 3) on both sides thereof. Further, the flow rate of the gas per unit area flowing into the bath from the respective regions (Al, C1) in the upper space is increased to be larger than the region (A2, A3, C2, C3) from the both sides thereof into the bath. The gas flow rate per unit area, the respective regions (4), C1) of the upper space correspond to the block at the central portion of the upstream column and the central portion of the downstream column, and flow from the upper space (4) to the bath The gas flow per unit area is reduced to less than the gas flow per unit area into the bath from the area (10) from both sides (10), 135680.doc 200930670, and the area above the upper space (B' 1) corresponds to The block in the central part of the middle row of the middle reaches. The third embodiment is an example in which the defect is caused on the one hand, and the flatness is also improved on the one hand. In the third embodiment, the heater output of the block (al) in the central portion of the upstream column and the block (^) in the central portion of the downstream column is interrupted, and the block (bli) in the central portion of the middle row of the middle row is interrupted. The heater output per unit area reaches less than 5% of the heater output per unit area of the blocks (b, 2, b, 3) on both sides. Further, the flow rate of the gas per unit area flowing into the bath from each region (Al, B, l) in the upper space is reduced to be smaller than the area from the both sides (A2, A3, B, 2, into the bath) The gas flow rate per unit area in the inner space, the respective regions (Al, B, l) of the upper space correspond to the block at the central portion of the upstream column and the central portion of the middle row and the rear segment, and the region from the upper space (C1) The flow rate of the gas per unit area flowing into the bath is increased to a gas flow rate per unit area larger than the area (C2, C3) flowing into the bath from the both side portions (C1) Corresponding to the block in the central part of the downstream column. [Table 1] The upper part of the upper swimming column is downstream of the middle row? ΐϊ - 丨 · Example 1 Central part a1 Both sides a2 > a3 12.3 Center part b, l — ~~ 52~~ Both sides are upper 2, b, 3 Central part cl c2, c3 __253 5 2 0 〇η 14.9 Gas flow rate Nm3/h · m2 3.2 3.2 3.2~~ Example 2 Heater output ΚΛν/m2 0 10.3 5.0 1_21 .9 0 2.9 1 -, 12.7 Gas flow rate Nm3/h · m2 5.3 2.9 3.2~~ 4 0 9 7 Example 3 Heater output KW/m2 Gas flow rate Nm3/lrm2 0 12.0 ~Ϊ5~ 6.5 ----- 6 0 Ζ· / 8.9 2.5 — _ 11.4 Example 4 Heater output KWmz 0 11.8 5.1 ν*\/ 22 0 0 13T ~ Gas flow rate Nm3/h · m2 2.1 2.1 3.2 6 Q 2.7 9.2 — .. 135680.doc -19- 200930670 Under the conditions of Examples 1 to 4, the glass ribbon without glass was formed. The result was ' The sheet glass which is excellent in flatness and has few defects is obtained as a glass substrate for liquid crystal displays. As described above, in the method of manufacturing the sheet glass of the present embodiment, the formation of the glass ribbon 4 is interrupted in a state where the flow of the molten glass 3 is stable. The output of the heater 11 of the block c1 at the central portion of the upstream column a of the region F1 and the block c at the central portion of the column of the downstream column c can thereby easily make the thickness of the glass ribbon* uniform in the width direction thereof. Further, the flow rate of the gas per unit area flowing into the bath 1 from the regions A1 and C1 in the space above the top wall 7 is reduced to a gas flow rate per unit area smaller than the area on both sides thereof, the top portion The area above the wall 7 is Al, C1 and glass The block a1 at the central portion of the upstream row 3 of the formation region F1 of the belt 4 and/or the block c丨 at the central portion of the downstream column c column, thereby preventing the ambient temperature in the two blocks a1, cl Excessively lowering, thereby inhibiting the condensation of molten metal vapor in the bath 18, preventing the agglomerates from falling on the surface of the glass ribbon. Thereby, it is possible to stably produce a plate glass which is excellent in flatness and has few defects.
相對應者，藉此可實現進一 或下游列c列的中央部之區塊C1 一步之平坦化。 135680.doc -20- 200930670 如上所述，特別係液晶顯示器用之無驗玻璃之情形時， 難以實現浮式法成形時之板玻璃的平坦化以及缺陷之抑 制’但是根據本發明’即便係無驗玻璃，亦可獲得平坦性 優良且缺陷較少之板玻璃。並且’於液晶顯示器用玻璃基 板之情形時’在浮式法成形後會研磨板玻璃表面，若為平 坦性優良且缺陷較少之板玻璃則可減少研磨量，從而可提 高生產性並且降低成本。此外’亦可藉由中斷區塊a丨、c i 之加熱器11，減少區域A1、Cl之每單位面積之氣體流 量，來通過大幅節能而降低成本。 此外，當緩冷後之玻璃帶4之寬度方向之板厚存在局部 偏差時’根據緩冷後之玻璃帶4之寬度方向之板厚，來控 制中游中段列之寬度方向之每單位面積之加熱器U的輸 出，藉此可抑制局部的板厚偏差。 再者’本發明並不限定於上述實施形態，而可適當自由 地加以變形、改良等。此外，只要可實現本發明，則上述 實施形態中之各構成要素之材質、形狀、尺寸、數值、形 態、數量、配置場所等均可任意設定而不加以限定。 再者，本申請案係基於2〇〇7年1〇月25日申請之曰本申請 案（曰本專利特願2007-277701)者，其内容以參照之方式而 併入於本文。 【圖式簡單說明】 圖1係表示實施本發明之板玻璃之製造方法之裝置之一 例的剖面圖。 圖2係圖1中之ΙΙ-Π線之剖面圖。 135680.doc -21- 200930670 圖3係圖2中之ΙΠ-ΙΙΙ線之剖面圖。 圖4係圖1中之IV-IV線之剖面圖。 【主要元件符號說明】 1 浴槽 2 熔融金屬 3 熔融玻璃 4 玻璃帶 7 頂部壁（頂部） 9 間隔板 10 供氣管 11 加熱器 17 上方空間 18 下方空間（浴槽内） ❹ 135680.doc -22-Correspondingly, the block C1 in the central portion of the column c of the upstream or downstream column can be flattened in one step. 135680.doc -20- 200930670 As described above, particularly in the case of a glass-free display for liquid crystal displays, it is difficult to achieve flattening of the sheet glass and suppression of defects during the floating molding process, but according to the present invention, In the case of glass inspection, it is also possible to obtain a plate glass which is excellent in flatness and has few defects. Further, in the case of a glass substrate for a liquid crystal display, the surface of the plate glass is polished after the floating method, and if the plate glass is excellent in flatness and has few defects, the amount of polishing can be reduced, thereby improving productivity and reducing cost. . Further, it is also possible to reduce the gas flow per unit area of the regions A1 and Cl by interrupting the heaters 11 of the blocks a 丨 and c i , thereby reducing the cost by greatly saving energy. Further, when there is a local variation in the thickness of the glass ribbon 4 in the width direction after the slow cooling, the heating per unit area in the width direction of the mid-middle row is controlled according to the thickness of the glass ribbon 4 in the width direction of the slow cooling. The output of the device U, whereby local thickness deviation can be suppressed. Further, the present invention is not limited to the above embodiment, and can be modified, improved, and the like as appropriate. In addition, as long as the present invention can be realized, the materials, shapes, dimensions, numerical values, shapes, numbers, arrangement places, and the like of the respective constituent elements in the above embodiments can be arbitrarily set without being limited. In addition, the present application is based on the present application filed on Jan. 25, 2008, the entire disclosure of which is hereby incorporated by reference. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing an example of an apparatus for carrying out the method for producing a sheet glass of the present invention. Figure 2 is a cross-sectional view of the ΙΙ-Π line in Figure 1. 135680.doc -21- 200930670 Figure 3 is a cross-sectional view of the ΙΠ-ΙΙΙ line in Figure 2. Figure 4 is a cross-sectional view taken along line IV-IV of Figure 1. [Main component symbol description] 1 Bath 2 Molten metal 3 Molten glass 4 Glass ribbon 7 Top wall (top) 9 Spacer 10 Air supply pipe 11 Heater 17 Upper space 18 Lower space (in the bath) 135 135680.doc -22-