518560 5614twf.doc/006 五、發明說明（(） --------------裝—— (請先閱讀背面之注咅？事項H寫本頁) 本發明是有關於一種光碟機伺服控制系統，且特別是 有關於一種光碟片(儲存媒體)於光碟機中運轉時，能獲得其 偏心距離的量化（偵S!i)方法，以及應用此偵測方法之光碟機 伺服系統。 由於資訊科技的不斷提昇，傳統磁碟機（Disk)因其發 展空間有限，加上其儲存容量不大，因此磁碟機已有漸漸 地被光碟機(Optical Disk Drive)所取代的趨勢。由於光碟機 具有高容量等優點，可同時儲存大量資料，加上可讀寫光 碟的產生，使得光碟機已被大眾所廣泛地使用。 •線」 光碟機伺服控制系統中，使用一循軌誤差（Tracking Error，以下簡稱TE)訊號，以得知聚焦點偏移碟片資料軌 的誤差量。以TE訊號的中心準位來作爲參考電位，則可再 得出循軌誤差零交越（Tracking Error Zero Cross，以下簡稱 TEZC)訊號。而TEZC訊號一次的上下可代表光碟片已經跨 越一個軌道。在做尋軌(track seeking)過程中，光碟機更可 利用這個訊號來計算光學讀取頭所跨的軌數，以及控制光 學讀取頭由光碟片的內圈移往外圈速度的快慢。 經濟部智慧財產局員工消費合作社印製 習知CD光碟片中軌與軌間的軌距約爲1.如111，而DVD 光碟片之軌距約爲0·74μιη。當任何光碟片放入光碟機中， 以光碟機之主軸馬達及磁鐵等方法來夾箝光碟片時，必然 或多或少有偏心現象存在。何況光碟片本身亦存在有一偏 心量，而光碟片本身之偏心量以及箝制時之誤差相對於 1·6μΐΉ，甚至0·74μιη這麼微小之軌距，就成爲一個不容忽視 的問題。 3 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 經濟部智慧財產局員工消費合作社印製 518560 5614twf.doc/006 五、發明說明（工） 光碟機循軌伺服控制系統中，碟片偏心量之大小即影 響了輸入系統之擾動量（disturbance)大小。而習知光碟機作 循軌動作時，由於並未偵測運轉中光碟片之偏心距離，只 得以固定規格之控制器作補償，造成伺服器無法涵蓋所有 的狀況。在讀取偏心量較大之光碟片時，將造成循軌及尋 軌控制的不穩定。但問題是，對於偏心嚴重之光碟，可能 使系統根本無法在高轉速環境下正常地循軌或尋軌。所以 習知之光碟機只能採用嘗試錯誤的方法，將光碟片之轉速 設爲最高速。如果無法作鎖軌或尋軌動作，則逐步降低轉 速。雖然最後都能穩定下來，但卻嚴重犧牲了光碟機之效 能。另一種習知之光碟機，縱然能判斷光碟片是否偏心， 但由於不能將光碟片之偏心程度與予量化，故並無法對伺 服器產生更大的幫助。 本發明提供一種光碟片偏心程度的偵測方法及應用 其之光碟機伺服系統，可將光碟片之偏心程度予以量化。 而光碟機伺服系統能根據光碟片之偏心距離自動作調整， 例如微調補償器之規格，或者直接設定較適宜的轉速，使 其可涵蓋所有的狀況。亦即本發明可克服循軌控制不穩 定，而無法循軌的現象發生，光碟機因而可達到最高的效 能。 本發明所提供之一種光碟片偏心程度的偵測方法，係 運用於光碟機中，此光碟機至少包括有聚焦伺服系統，則 上述偵測方法包括下列步驟：首先於光碟機運轉時，鎖上 (lock)此光碟機之聚焦伺服系統，令循軌伺服系統保持關 4 氏張尺度適用中關家標準（CNS)A4規格（21G X 297公爱)"" ~ --------------裝--- (請先閱讀背面之注意事項HI寫本頁) 訂： !線· 518560 5614twf.doc/006 A7 B7 經濟部智慧財產局員工消費合作社印製 五、發明說明（$ ) 閉；此時同時偵測讀寫頭傳回之循軌誤差訊號；再利用此 循軌誤差訊號，來偵測光碟片旋轉預定周數的期間’光碟 片上聚焦點所跨越資料軌之跨軌數；以及最後利用此跨軌 數、預定周數以及光碟片資料軌間之軌距’以求出此光碟 片之偏心距離。上述求出光碟片之偏心距離之方法係爲： 偏心距離=跨軌數*軌距/(預定周數*4)。 依據本發明實施例之一種光碟片偏心程度的偵測方 法，係運用於光碟機中，此光碟機至少包括有聚焦伺服系 統，則偵測方法包括下列步驟··首先於光碟機運轉時’鎖 上此光碟機之聚焦伺服系統；此時同時偵測循軌誤差訊 號；以及利用此循軌誤差訊號’計算此光碟片旋轉1/4週的 期間，光碟機之聚焦點所跨越之跨軌數，再將其乘以軌距 即爲此光碟片之偏心距離。 本發明所提供之一種光碟機之伺服系統，運用於光碟 機中，此光碟機可讀取光碟片上之資料，上述伺服系統包 括：用以接受循軌誤差訊號之循軌演算裝置，其送出能做 循軌控制之循軌控制訊號；偏心偵測器，其接受循軌誤差 訊號以及轉速訊號，以求得此光碟片之偏心程度；補償器’ 耦接至循軌演算裝置以及偏心偵測器，用以依據上述求得 之偏心程度，進一步控制循軌控制訊號，以使聚焦點正確 位於預定軌道上。其中偏心偵測器，係利用循軌誤差訊號 以及轉速訊號，來偵測光碟片旋轉預定周數的期間之跨軌 數，再利用此跨軌數、預定周數以及軌距，以求出代表此 光碟片之偏心程度的偏心距離。例如利用：偏心距離=跨 5 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） (請先閱讀背面之注意事項^^寫本頁)518560 5614twf.doc / 006 V. Description of the invention (() -------------- Installation-- (Please read the note on the back first? Matters H write this page) This invention is about An optical disc drive servo control system, and in particular, it relates to a quantization (detection S! I) method for obtaining an eccentric distance when an optical disc (storage medium) is running in the optical disc drive, and an optical disc drive applying the detection method Servo system. Due to the continuous improvement of information technology, traditional disk drives (Disks) have been gradually replaced by optical disk drives (Optical Disk Drives) due to their limited development space and small storage capacity. Trend. Due to the high capacity of the optical disc drive, it can store a large amount of data at the same time, and the generation of readable and writable optical discs has made the optical disc drive widely used by the general public. Tracking Error (TE) signal to know the amount of deviation of the focus point from the disc data track. Using the center level of the TE signal as the reference potential, the zero crossing of the tracking error can be obtained. (Tracking Error Zero Cros s (hereinafter referred to as TEZC) signal. The TEZC signal can be used to indicate that the optical disc has crossed a track. In the process of track seeking, the optical disc drive can also use this signal to calculate the span of the optical pickup head. The number of tracks, and the speed of controlling the speed at which the optical pickup moves from the inner circle to the outer circle of the disc. The Intellectual Property Bureau of the Ministry of Economic Affairs, the Consumer Cooperative Cooperative, prints the track distance between the middle and the track of the CD disc. , And the track pitch of DVD discs is about 0.74μιη. When any disc is placed in the disc drive, the spindle motor and magnet of the disc drive are used to clamp the disc, there must be more or less eccentricity. Moreover, there is also an eccentricity in the optical disc itself, and the eccentricity of the optical disc itself and the error during clamping are relatively small as compared to 1.6 μΐΉ, or even 0. 74 μιη, which becomes a problem that cannot be ignored. 3 This paper Standards are applicable to China National Standard (CNS) A4 specifications (210 X 297 mm) Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 518560 5614twf.doc / 006 In the tracking servo control system of the machine, the amount of eccentricity of the disc affects the amount of disturbance of the input system. However, when the conventional optical disc drive is in tracking operation, the eccentric distance of the disc in operation is not detected. It can only be compensated by a controller with a fixed specification, causing the server to not cover all conditions. When reading a disc with a large eccentricity, it will cause the tracking and tracking control to be unstable. However, the problem is that the eccentricity Severe discs may make the system unable to track or track normally under high-speed environments. Therefore, the conventional optical disc drive can only use trial and error methods to set the speed of the optical disc to the highest speed. If it is impossible to perform the track locking or tracking operation, gradually reduce the speed. Although it finally stabilized, it seriously sacrificed the performance of the optical disc drive. Another conventional optical disc drive, although it can judge whether the optical disc is eccentric, but cannot quantify the degree of eccentricity of the optical disc, so it cannot provide greater help to the server. The invention provides a method for detecting the eccentricity of an optical disc and an optical disc drive servo system using the same, which can quantify the eccentricity of the optical disc. The servo system of the optical disc drive can automatically adjust according to the eccentric distance of the optical disc, such as fine-tuning the specifications of the compensator, or directly setting a more appropriate rotation speed so that it can cover all conditions. That is, the present invention can overcome the instability of the tracking control and the phenomenon that the tracking cannot be performed, so that the optical disc drive can achieve the highest performance. A method for detecting the eccentricity of an optical disc provided by the present invention is applied to an optical disc drive. The optical disc drive includes at least a focus servo system. The above detection method includes the following steps: first, when the optical disc drive is running, it is locked. (lock) The focus servo system of this optical disc drive keeps the tracking servo system closed. The 4th scale is applicable to the CNS A4 specification (21G X 297 public love) " " ~ ------ -------- Installation --- (Please read the note on the back HI first to write this page) Order:! Line · 518560 5614twf.doc / 006 A7 B7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs Description of the invention ($) closed; at this time, the tracking error signal returned by the head is simultaneously detected; and then the tracking error signal is used to detect the data spanned by the focus point on the disc during a predetermined number of rotations of the disc The number of cross-tracks of the track; and finally, the number of cross-tracks, the predetermined number of weeks, and the track distance between the data tracks of the optical disc are used to obtain the eccentric distance of the optical disc. The above-mentioned method for obtaining the eccentric distance of the optical disc is: eccentric distance = number of cross tracks * track distance / (predetermined number of cycles * 4). A method for detecting the eccentricity of an optical disc according to an embodiment of the present invention is applied to an optical disc drive. The optical disc drive includes at least a focus servo system. The detection method includes the following steps. Focus servo system of the optical disc drive; at this time, tracking error signal is detected at the same time; and using this tracking error signal 'to calculate the number of cross-tracks that the focus point of the optical disc drive spans during the 1/4 rotation of the optical disc rotation , Then multiply it by the track gauge to obtain the eccentric distance of the disc. A servo system for an optical disc drive provided by the present invention is used in the optical disc drive. The optical disc drive can read data on the optical disc. The servo system includes a tracking calculation device for receiving a tracking error signal. Tracking control signal for tracking control; Eccentricity detector, which accepts tracking error signal and speed signal to obtain the eccentricity of the disc; compensator 'is coupled to the tracking calculation device and eccentricity detector , For further controlling the tracking control signal according to the degree of eccentricity obtained above, so that the focus point is correctly positioned on a predetermined track. The eccentricity detector uses the tracking error signal and the speed signal to detect the number of cross-tracks during a predetermined number of rotations of the disc, and then uses the number of cross-tracks, the predetermined number of cycles, and the track pitch to obtain a representative The eccentricity of the eccentricity of this disc. For example, use: eccentric distance = span 5 This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 mm) (Please read the precautions on the back first ^ Write this page)
言Speech
T 518560 A7 5614twf.doc/006 B7 經濟部智慧財產局員工消費合作社印製 五、發明說明（¥) 軌數*軌距/(預定周數*4)，以求出此光碟片之偏心距 離。 爲讓本發明之上述和其他目的、特徵、和優點能更明 顯易懂，下文特舉一較佳實施例，並配合所附圖式，作詳 細說明如下： 圖式之簡單說明： 第1A圖係顯示一種光碟片之讀取資料偏心時的不意 圖。 第1B圖係顯示一種光碟機之聚焦點跨越資料軌時循 軌誤差訊號的波形示意圖。 第2圖係顯示根據本發明一較佳實施例之一種光碟片 偏心程度的偵測方法的流程圖。 第3圖係顯示應用本發明之一種應用光碟片偏心程度 的偵測方法之一較佳實施例的光碟機伺服系統之方塊示意 圖。 圖式標號之簡單說明： 10光碟片 12讀取軌跡圓 14貪料軌軌跡圓 30伺服控制副系統 32循軌演算裝置 34偏心偵測器 36, 46補償器 38光感測器 6 (請先閱讀背面之注音？事項^^寫本頁) 裝 訂！ -·線」 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公爱） 518560 5614twf.doc/006 ___B7___ 五、發明說明（f ) 40前置放大器 42,48電力驅動器 44致動器 4 50雪橇馬達 實施例 第1A圖係顯示一種光碟片（儲存媒體）之讀取資料偏心 時的示意圖。請參照第1A圖，光碟片10上有一真實的資料 軌軌跡圓14，當此光碟片10置於某一光碟機中運轉時，假 如令光碟機之聚焦伺服系統鎖上，令循軌伺服系統保持關 閉，則光碟機之聚焦點的軌跡在旋轉的光碟片上會形成一 個讀取軌跡圓12。 經濟部智慧財產局員工消費合作社印製 -------— — — — — — — ^ - I I (請先閱讀背面之注意事項HI寫本頁) --線」 假設，資料軌軌跡圓14的圓心G與讀取軌跡圓12的圓 心C。之距離爲C，且目前光碟機之聚焦點p距離圓心C〇之距 離爲L，則光碟片旋轉時的角位移0爲18〇°時，聚焦點P與真 實資料軌軌跡圓14的圓心Ci的距離最遠，其距離爲L+C，而 光碟片的角位移0爲0°時，聚焦點P與真實資料軌軌跡圓14 的圓心Ci的距離最近，其距離爲L-C，所以當光碟機之聚焦 伺服系統鎖上，光碟片旋轉半周期間，聚焦點事實上跨過 了等於2C距離的資料軌，同理，光碟片旋轉一周期間，聚 焦點事實上跨過了等於4C距離的資料軌。 _ 第1B圖係顯示一種光碟機之聚焦點跨越資料軌時循 軌誤差訊號TE的波形示意圖。請參照第⑺圖，由圖上可輕 易知曉’每當光碟機之聚焦點跨越一個資料軌時，循軌誤 差訊號TE恰變化了一個完整的波形，如果以τε訊號的中心 7 ^紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） ---- 518560 A7 5614twf.doc/006 i、發明說明（‘） ------------裝 i I (請先閱讀背面之注意事項寫本頁) 準位來作爲參考電位，則可得出循軌誤差零交越TEZC訊 號。TEZC訊號一次的上下可代表光碟片已經跨越一個軌 道，所以，以計數器來計算TEZC訊號的次數，則可輕易得 到光學讀取頭之聚焦點所跨的資料軌軌數。 --線」 第2圖係顯示根據本發明一較佳實施例之一種光碟片 偏心程度的量化(偵測)方法的流程圖。本發明所提供之一種 光碟片偏心程度的偵測方法，主要運用於光碟機中。當然 光碟機中都至少包括有聚焦伺服系統。則本發明之偵測方 法包括下列步驟：首先執行步驟S20，於光碟機運轉中，鎖 上此光碟機之聚焦伺服系統，令循軌伺服系統保持關閉。 此時執行步驟S22，偵測光碟機之讀寫頭所傳回的循軌誤差 訊號TE。然後執行步驟S24,利用此循軌誤差訊號TE，在光 碟片旋轉預定周數的期間，例如爲η周期間，計算出光碟片 上聚焦點所跨越資料軌之跨軌數，例如利用TEZC訊號。最 後再執行步驟S26，利用此跨軌數、預定周數以及光碟片資 料軌間真實的軌距，以求出此光碟片之偏心距離。例如利 用： 偏心距離=跨軌數*軌距/(預定周數*4) 經濟部智慧財產局員工消費合作社印製 來求出光碟片之偏心距離，式中預定周數爲η，而一般之光 碟片（Compact Disc)軌距爲1·6μηι。而DVD(數位多用途光碟) 之軌距則爲〇.75μηι。 如熟悉此藝者可輕易知曉，依據本發明實施例之一種 光碟片偏心程度的偵測方法，可簡化成包括下列步驟··首 先於光碟機運轉時，鎖上此光碟機之聚焦伺服系統；此時 8 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 518560 A7 5614twf.doc/006 ______ B7 五、發明說明（rp 同時偵測循軌誤差訊號；以及利用此循軌誤差訊號，計算 此光碟片旋轉1/4週的期間，光碟機之聚焦點所跨越之跨軌 數，再將其乘以軌距即爲此光碟片之偏心距離。 第3圖係顯示應用本發明之一種應用光碟片偏心程度 的偵測方法之一較佳實施例的光碟機伺服系統之方塊示意 圖。請參照第3圖，此光碟機伺服系統包括：光感測器 38(optical sensor)、前置放大器40(Pre-amplifier)、伺服控制 副系統30(server control sub-system)、電力驅動器42, 48(power driver)、補償器46(compensator)，致重力器44(actuator)、以及 雪橇馬達50(sled motor)。其中之伺服控制副系統30更包括： 循軌演算裝置32、偏心偵測器34、以及補償器36。本發明 之精華主要係在此伺服控制副系統30中，故集中討論這 裡，習知技藝者當可輕易知曉其他部分。 經濟部智慧財產局員工消費合作社印製 ----------I__I ___ (請先閱讀背面之注意事項ml寫本頁) 本發明所提供之光碟機伺服控制副系統，主要運用於 光碟機中，此光碟機主要用於讀取光碟片上之資料。首先， 由光學讀取頭上之光感測器38的感測光碟片上之資料，再 經前置放大器40傳來循軌誤差訊號，送給本發明之循軌演 算裝置32。經過循軌演算裝置32演算處理後，送出能做循 軌控制之循軌控制$ 5虎。此時’偏心偵測器3 4，同樣接受 到循軌誤差訊號，其同時根據光碟片之轉速訊號，來求得 此先碟片之偏心程度。最後’鍋接至循軌演算裝置3 2以及 偏心偵測器34之補償器36，依據上述求得之偏心程度，進 一步控制循軌控制訊號，以使聚焦點正確位於預定軌數 上。 9 本紙張尺度適用中國國家標準（CNS)A4規格（210 X 297公釐） 518560 5614twf.doc/006 五、發明說明（》） 上述的偏心偵測器34，係利用循軌誤差訊號以及轉速 訊號，來偵測光碟片旋轉預定周數的期間之跨軌數。再利 用此跨軌數、預定周數以及軌距，以求出代表此光碟片之 偏心程度的偏心距離。例如利用：偏心距離=跨軌數*軌 距/(預定周數*4)，以求出此光碟片之偏心距離。 如熟悉此藝者可輕易知曉，本發明之偏心偵測器36亦 可耦接至循軌演算裝置32，以直接提供有關光碟片偏心程 度的資訊給循軌演算裝置32。 由上述之實施例可知本發明所提供之一種光碟片偏 心程度的偵測方法及應用其之光碟機伺服系統，可將光碟 片之偏心程度與予量化，使光碟機伺服系統能根據光碟片 之偏心距離自動作調整。所以光碟機伺服系統可涵蓋所有 的狀況’亦即不會有循軌控制不穩定，而無法循軌的現象 發生’光碟機因而可達到最高的效能。 雖然本發明已以一較佳實施例揭露如上，然其並非用 以限定本發明，任何熟習此技藝者，在不脫離本發明之精 /神和範11內’當可作各種之更動與潤飾，因此本發明之保 護範圍當視後附之申請專利範圍所界定者爲準。 (請先閱讀背面之注意事項寫本頁)' 裝 訂·- 經濟部智慧財產局員工消費合作社印製 本紙張尺度適用中國國家標準（CNS)A4 ^格（210 X 297公釐）T 518560 A7 5614twf.doc / 006 B7 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. 5. Description of the invention (¥) Number of tracks * track pitch / (predetermined number of weeks * 4) to find the eccentricity of the disc. In order to make the above and other objects, features, and advantages of the present invention more comprehensible, a preferred embodiment is described below in detail with the accompanying drawings as follows: Brief description of the drawings: FIG. 1A It shows the inadvertence when the read data of the disc is eccentric. FIG. 1B is a waveform diagram of a tracking error signal when a focus point of an optical disc drive crosses a data track. FIG. 2 is a flowchart showing a method for detecting the eccentricity of an optical disc according to a preferred embodiment of the present invention. Fig. 3 is a schematic block diagram of an optical disc drive servo system showing a preferred embodiment of a method for detecting the eccentricity of an optical disc using the present invention. Brief description of the drawing numbers: 10 optical discs 12 reading track circle 14 material track track circle 30 servo control subsystem 32 tracking calculation device 34 eccentric detector 36, 46 compensator 38 light sensor 6 (please first Read the Zhuyin on the back? Matters ^^ Write this page) Binding! -· Line "This paper size applies Chinese National Standard (CNS) A4 specification (210 X 297 public love) 518560 5614twf.doc / 006 ___B7___ V. Description of the invention (f) 40 preamplifier 42, 48 electric drive 44 actuator 4 50 Sleigh Motor Example 1A is a schematic diagram showing the eccentricity of reading data of an optical disc (storage medium). Please refer to FIG. 1A. There is a real data track trajectory circle 14 on the optical disc 10. When the optical disc 10 is operated in a certain optical disc drive, if the optical disc drive's focus servo system is locked, the tracking servo system Keep it closed, the track of the focus point of the optical disc drive will form a reading track circle 12 on the rotating disc. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs ----------- — — — — — — ^-II (please read the note on the back HI first to write this page)-line "Hypothesis, the data track trajectory circle A circle center G of 14 and a circle center C of the read track circle 12. When the distance is C, and the distance between the focal point p of the optical disc drive and the center of the circle C is L, when the angular displacement 0 of the disc is 180 °, the focus point P and the center of the real data track circle 14 are Ci The farthest distance is L + C, and when the angular displacement of the disc is 0 °, the distance between the focus point P and the center Ci of the circle 14 of the real data track is the closest, and the distance is LC, so when the optical disc drive The focus servo system is locked. During the half rotation of the disc, the focus point actually crosses the data track equal to a distance of 2C. Similarly, during the rotation of the disc, the focus point actually crosses the data track equal to a distance of 4C. _ Figure 1B is a waveform diagram of the tracking error signal TE when the focus point of the optical disc drive crosses the data track. Please refer to the second figure, which can be easily known from the figure. 'Every time the focus point of the optical disc drive crosses a data track, the tracking error signal TE changes a complete waveform. If the center of the τε signal 7 ^ paper scale applies China National Standard (CNS) A4 specification (210 X 297 mm) ---- 518560 A7 5614twf.doc / 006 i. Description of the invention (') ------------ install i I (please First read the notes on the back page and write this page) level as a reference potential, then you can get the tracking error zero crossing TEZC signal. The up and down of the TEZC signal can indicate that the disc has crossed a track. Therefore, counting the number of times of the TEZC signal by a counter can easily obtain the number of data tracks spanned by the focus point of the optical pickup. "Line" Figure 2 is a flowchart showing a method for quantifying (detecting) the degree of eccentricity of an optical disc according to a preferred embodiment of the present invention. The method for detecting the eccentricity of an optical disc provided by the present invention is mainly used in an optical disc drive. Of course, the optical disc drive includes at least a focus servo system. Then, the detection method of the present invention includes the following steps: First, step S20 is performed. During the operation of the optical disc drive, the focus servo system of the optical disc drive is locked to keep the tracking servo system closed. At this time, step S22 is executed to detect the tracking error signal TE returned by the read / write head of the optical disc drive. Then, step S24 is executed, and the tracking error signal TE is used to calculate the number of cross-tracks of the data track spanned by the focus point on the disc during a predetermined number of rotations of the disc, for example, η period, for example, using a TEZC signal. Finally, step S26 is performed, and the number of eccentric tracks, the predetermined number of cycles, and the actual track pitch between the tracks of the disc data are calculated. For example, use: eccentric distance = number of cross tracks * track distance / (predetermined number of weeks * 4) printed by the employee's consumer cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs to find the eccentric distance of the disc, where the predetermined number of weeks is η, and in general The track pitch of a compact disc is 1.6 μm. The track pitch of DVD (Digital Versatile Disc) is 0.75 μηι. As those skilled in the art can easily know, a method for detecting the eccentricity of an optical disc according to an embodiment of the present invention can be simplified to include the following steps: First, when the optical disc drive is running, the focus servo system of the optical disc drive is locked; At this time, the 8 paper sizes are in accordance with the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 518560 A7 5614twf.doc / 006 ______ B7 V. Description of the invention (RP simultaneously detects tracking error signals; and uses this tracking The error signal is used to calculate the number of cross-tracks spanned by the focus point of the optical disc drive during the 1/4 rotation of the disc, and then multiplying the track pitch to the eccentric distance of the disc. Figure 3 shows the application. A block diagram of an optical disc drive servo system according to a preferred embodiment of the invention is a method for detecting the eccentricity of an optical disc. Please refer to FIG. 3. This optical disc drive servo system includes: an optical sensor 38 (optical sensor), Pre-amplifier 40, server control sub-system 30, power drivers 42, 48 (power driver), compensator 46, actuator 44, and Sled motor 50 (sled motor). The servo control sub-system 30 further includes: a tracking calculation device 32, an eccentricity detector 34, and a compensator 36. The essence of the present invention is mainly in this servo control sub-system 30, So focus on the discussion here, and the skilled artisan can easily know the other parts. Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs ---------- I__I ___ (Please read the precautions on the back first to write this page The servo control sub-system of the optical disc drive provided by the present invention is mainly used in the optical disc drive. This optical disc drive is mainly used to read the data on the optical disc. First, the optical disc is sensed by the optical sensor 38 on the optical pickup head. The data on the chip sends the tracking error signal through the preamplifier 40 and sends it to the tracking calculation device 32 of the present invention. After the tracking calculation device 32 performs the processing, it sends a tracking control that can be used for tracking control. 5 Tiger. At this time, the eccentricity detector 3 4 also receives the tracking error signal, and at the same time, the eccentricity of the previous disc is obtained according to the rotation speed signal of the optical disc. Finally, the pot is connected to the tracking calculation device. 3 2 and eccentricity The compensator 36 of the detector 34 further controls the tracking control signal according to the eccentricity obtained above, so that the focus point is correctly located on a predetermined number of tracks. 9 This paper standard is applicable to the Chinese National Standard (CNS) A4 specification (210 X 297 mm) 518560 5614twf.doc / 006 V. Description of the invention (") The above-mentioned eccentricity detector 34 uses the tracking error signal and the speed signal to detect the cross-track during a predetermined number of rotations of the disc number. The number of cross-tracks, the predetermined number of cycles, and the track pitch are then used to obtain the eccentric distance representing the eccentricity of the disc. For example, use: eccentric distance = number of cross tracks * track distance / (predetermined number of cycles * 4) to find the eccentric distance of this disc. If an artist familiar with this art can easily know, the eccentricity detector 36 of the present invention can also be coupled to the tracking calculation device 32 to directly provide information about the eccentricity of the optical disc to the tracking calculation device 32. According to the foregoing embodiments, a method for detecting the eccentricity of an optical disc and an optical disc drive servo system provided by the present invention can be used to quantify the eccentricity of the optical disc and enable the optical disc drive servo system to The eccentricity is automatically adjusted. Therefore, the servo system of the optical disc drive can cover all the conditions, that is, there will be no tracking control instability, and the phenomenon of untracking will occur. The optical disc drive can thus achieve the highest performance. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make various changes and decorations without departing from the spirit / sacredness of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the appended patent application. (Please read the note on the back first to write this page) 'Binding ·-Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs This paper size applies to Chinese National Standard (CNS) A4 ^ (210 X 297 mm)