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200948203 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種用於螢光燈之脈衝式操作的方法與電 路、一種包含該電路的鎮流器以及一種該電路與該勞光燈 的總成。 【先前技術】 US 5 907 222揭示了一種用於驅動螢光燈的控制器。該 控制器包含一弧電流調整器及一燈絲電流調整器。當該燈 以脈衝或暗淡方式操作時，必須加熱燈的電極以將燈保持 為一操作工作區域及以保證燈的點亮。又提供了 一分離 燈絲電流調整器，其提供燈絲電流以加熱燈的電極，i一 分離弧電流調整器以控制弧電流及該燈上的電壓。 不論此種控制器的優勢為何’必須有一個相當複雜的電 路’因為本質上提供了-雙重控制之事實，該事實會增加 電路的複雜性，從而可能以不利方式影響_個或多個設計 參數，諸如成本、體積、零件計數等等。 【發明内容】 本發明之-目標係藉由—種簡單的控制電路來控制榮光 燈電極的加熱以及燈的點亮與弧電流。 上述目標可藉由一種用於一蕃氺 '螢光燈之脈衝式操作的方法 來實現，該方法包含： -經由具有頻率相依轉移函數的一網路，給該燈提供一 電源信號； 在一脈衝重複時間週期 的一加熱部分期間 ，控制該電 130982.doc 200948203 源信號的一頻率於一第一頻帶内以便將一電極電流提供給 該燈來加熱該燈的一個電極；及 - 在該脈衝重複時間週期的一操作部分期間，控制該電 源信號的該頻率於一第二頻帶内以便點亮該燈及將弧電流 與電極電流提供給該燈。 進一步，在本發明之一態樣中，上述目標可藉由一種用 • 於一螢光燈之脈衝式操作的電路來實現，該電路包含： -一電源信號產生器，用於產生一電源信號以供電給該 ❹ 燈， -一網路，其具有一頻率相依轉移函數，該網路被連接 至該電源信號產生器及用於將該電源信號提供給該燈；及 一燈控制器，用於驅動該電源信號產生器，該燈控制器具 有一設定輸入以接收一設定輸入信號且被配置為用以： 當該設定輸入在一第一位準時，控制該電源信號產生器 以將該電源信號的一頻率設定在一第一頻帶内以便將一電 極電流提供給該燈來加熱該燈的一個電極；及 ❿ 當該設定輸入在一第二位準時，控制該電源信號產生器 以將該電源信號的該頻率設定在一第二頻帶内以便點亮該 - 燈及將弧電流與電極電流提供給該燈。 - 根據本發明，燈驅動頻率將交替地設定於一第一頻帶内 及-第二頻帶内。在該第一頻帶内，由於共振網路的頻率 相依性，燈上的電壓相對較低。因為該低電壓，燈中的一 個弧將無法維持’且因此燈將關閉。經由網路流過電極的 電流將僅加熱該等電極。當頻率被帶向該第二頻帶時，燈 130982.doc -8 - 200948203 上的電壓將增加，這將導致燈的點亮。該燈在第二時間週 力期門保持導通’及在第二時間週期結束當頻率改變時將 被關掉，因為那一刻恰好燈上的電壓由於頻率的變化而減 因此，燈的脈衝式操作及電極的加熱可用一單驅動信 號來實現。此外，單驅動電路能為兩個時間週期内電流的 . ㈣提供-單控制電路。作為-項實例，該網路可包含一 ”振網路’諸如一電感器’電容器共振網路，第一頻帶選 擇為在該共振網路之一共振頻帶之外，而第二頻帶選擇為 _ 在該八振頻帶之内。藉由共振，可獲得驅動燈之電量(諸 如電壓）的-有效增加’這容許第二頻帶設定於共振頻帶 内之時燈的可靠點党。其他實施例也是可行的，作為一項 實例’第二頻帶可低於此種共振網路的一#振頻帶。在其 實施例巾1¾網路可包含具有顯示出頻率相依性之一個 或多個零件的任何適當網路，諸如更多電容器之一，更多 電感器、變壓器之一等等。 在根據本發明之電路巾，可提供-設定輸人，在設定輸 入的個彳5號用於將電源信號的頻率控制在第一或第二頻 帶内從而’燈的接通及切斷可藉由—外部信號來控制， - 這容許燈之脈衝式操作與諸如一外部源的同步。 在—實施例中，為了控制加熱電流，及因此穩定燈電極 的《•度，在脈衝重複週期的加熱部分期間，一參考源被設 疋至帛-輸出值，代纟流過燈之一電極電流的一信號與 該參考源的該第一輸出值相比較，且其中電源信號的頻率 基於代表該電極電流之該信號與該參考源之該第—輸出值 130982.doc 200948203 之間的比較而進行調整。 在一實施例中，為了控制弧電流，在脈衝重複週期的操 作部分期間’參考源被設定至一第二輸出值，代表電極電 流的一信號從一代表流過該燈之總電流的信號中減去，減 法結果與參考源的第二輸出值相比較，且其中電源信號的 頻率基於該減法結果與參考源之該第二值之間的比較而進 * 行調整。因此，藉由從代表通過燈之總電流的一信號減去 代表電極電流的一信號’獲得弧電流的一個指示，其可應 _ 用於控制及/或監視弧電流，及因此控制及/或監視燈的光 強度。 藉由改變脈衝重複週期之操作部分及加熱部分的比率， 及根據該改變比率來改變參考源的第一輸出值，以使一期 望電極電流適應於加熱部分的改變持續期間對脈衝循環 之電極加熱部分之作用時間循環的變動可補償電極加熱， 以藉此諸如保持一期望電極溫度。 運用根據本發明之電路，可提供實現如上述相同或相似 攀 效應的多項相似較佳實施例。 在根據本發明之電路的__進—步較佳實施例中，該控制 器可藉由簡單、具成本效率的電路形成，其中該控制器 包含一對雙極電晶體，該等雙極電晶體的各自基極電連 接，該等雙極電晶體的射極分別電連接至參考源及電連接 至代表流過該燈之總電流的信號，該等電晶體中之一者的 一集極電連接至一積分器或該控制器。 此外’為了容許該控制器調整該電源信號的頻率，該電 130982.doc 200948203 源信號產生器可包含一受控振盪器，該振盪器的頻率係可 受控於該振盪器的一電輸入量，該積分器的輸出電連接至 用於提供該電輸入量的該受控振盪器。 更進一步’當該網路包含一連接於該燈之該等電極之間 的電極電流供應電容時，該控制器可包含一電容器，該電 容器之一終端連接至燈的一驅動側電極，該電容器用於提 . 供一電流以透過該電流提供代表加熱電流的信號：發明者 已認識到可藉由將一電容器之一終端連接到該驅動側電極 〇 (即，燈的"熱"側’此處藉由該網路提供一高電壓給該燈） 以及將該電容器之另一終端保持在與該燈之另一電極的電 壓相似之低電壓而獲得電極加熱電流（其還流過電流供應 電極）的一個指示’通過電容器的電流提供通過該燈之該 等電極之電流的一指示。 本發明進一步包含一種用於驅動螢光燈的鎮流器，該鎮 流器包含根據本發明的一電路。 更進一步，本發明包含一種一螢光燈與根據本發明之一 © 電路的總成。 【實施方式】 圖1描繪燈驅動頻率對時間的曲線圖。沿著水平轴描缘 時間，而沿著垂直軸描繪燈驅動電源信號pS。如圖1所說 明，該燈用一交流電源信號來驅動，該電源信號的頻率隨 時間而改變。請注意，燈上的振幅或電壓也可能由於頻率 的變化而改變’諸如由於燈被驅動所經由之網路的頻率相 依性，如下文將更詳細解釋的。請注意在此實例中，該網 130982.doc •11- 200948203 路包含一共振網路，如下文將更詳細概述的。如圖丨所描 繪的，此實施例中的燈驅動信號顯示一第一時間週期τι， 其中該燈驅動信號具有一第一頻率（更一般而言：其令該 燈驅動仏號係在一第一頻率範圍或頻帶内），及一第二時 間週期T2,其中該燈驅動信號具有一第二頻率（更一般而 吕.其中該燈驅動信號係在一第二頻率範圍或頻帶内 ， 在此實例中，在該第一時間週期T1内，燈驅動頻率高於該 網路的一共振頻率，而在該第二時間週期仞内，燈驅動頻 ❿ 率在該網路的一共振頻帶内。在第一週期内，由於共振網 路的頻率相依性，燈上的電壓相對較低。因為該低電壓， 燈中的一個弧將無法維持，且因此燈將關閉。經由網路流 過電極的電流將僅加熱該等電極。當頻率被降低及帶向燈 的共振頻帶時，燈上的電壓將增加，這將導致燈的點亮。 該燈在第二時間週期期間保持導通，及在第二時間週期結 束當頻率增加時將被關掉，因為那一刻恰好燈上的電壓由 於頻率的變化而減少。T1&T2一起形成脈衝重複時間週期 ® Τ，如圖1所描繪的。在此文件中，術語共振頻帶應理解為 於其中網路顯示出一定程度之共振的一種頻帶，舉例而言 . 其中5%或更多峰達一適當的電轉移特性。如圖3所描繪 的，該網路可包含一電感器與一電容器的一組合。或者， 該網路可包含一變壓器與一電容器的一組合。也可應用任 何其他網路。在圖3所描繪的實例中，該網路包含一旁路 電容器Cr ’該旁路電容器連接於該燈相對側的電極之間。 流過s亥等電極的加熱電流藉由該旁路電容器從該等電極的 130982.doc •12· 200948203 第一個被引導至該等電極的第二個。圖3中的網路進一步 包含電感器L。Cs形成-輕合電容器，其與電感器L串聯連 接，以容許燈的單端（即單供應電壓）驅動。 圖2顯不了 一種用於驅動螢光燈TL之電路的方塊示意 圖。電源10(諸如一主電源、—主電源配接器…電池或 一整流主電源）供應電能給電源電路2〇，該電源電路2〇經 . 由網路30給燈TL提供電源信號PS。電源電路20對藉由電 源10供應給其的電源進行操作，以產生一處於燈驅動頻率 © 的交流燈驅動電流。又，電源電路20可包含一半橋接器或 其他適當的開關元件。進一步，電源電路2〇可包含一振盪 器以產生燈驅動電流之頻率。該振盪器可包含一受控振盪 器，其可藉由燈控制器40控制。在此實例中，燈控制器被 提供有一代表通過燈TL之電流的回饋信號fb。控制器40 產生一控制信號以控制電源電路2〇，舉例而言藉由提供一 控制彳s號（諸如一電壓）給電源電路2〇的一受控振盪器（諸如 電壓受控振盪器）。該控制器進一步被提供有一設定輸 © 入S，回應在設定輸入S的一個適當信號及被提供有回饋信 號FB，該控制器驅動電源電路20以形成一回饋控制系統操 作該燈。藉由供應一個適當信號給設定輸入，提供給燈之 電源信號的頻率可被改變，因為回應在設定輸入S的一對 應信號，回饋迴路將穩定至一對應頻率。在一些實施例 中’設定輸入S可被提供有一類比信號以形成一設定點信 號，而在其他實施例中，設定輸入可形成一開關輸入，以 被提供諸如—個數位或相似之信號，以將該控制器的一内 130982.doc -13· 200948203 部參考設定為在設定輸入之輸入信號控制下的一個適當 值。在此等實施例中，在内部參考中，諸如一參考電壓源 可被提供’該參考電壓源的一個輸入值藉由在設定輸入s 的輸入信號控制，舉例而言以使參考電壓源在不同值之間 變化’以藉此使得回饋控制電路穩定於不同頻率。在如此 的一項實施例中，設定輸入可因此被提供一個在第一時間 ' 週期期間具有一第一位準及在第二時間週期期間具有一第 二位準的信號，以藉此用具有如圖1所描繪之頻率圖案的 Φ 一個電源信號來驅動燈。 圖3根據本發明顯示了電路之一實施例的更詳細的視 圖。如圖2所描繪的電源電路包含電壓受控振盪器vc〇及 一半橋接器，該半橋接器藉由Vhb示意性指示。網路3 0包 含電感器L、電容器Cr以橋接電極’及耦合電容器Cs，其 功能已在上文描述。一回饋信號藉由串聯電阻器R產生， 其提供一與燈總電流成正比的回饋電壓，燈總電流即經由 電容器Cr提供的電極電流以及燈導通情况下的弧電流。在 ❹ 此實例中，控制器40包含藉由電晶體Qi、q2形成的一比 較器 '藉由電容器Ci及電流源II形成的一積分器。參考信 - 號藉由電壓源V2產生，該電壓源V2藉由在輪入8將提供的 - 一個信號來控制。在脈衝重複週期的加熱部分期間，在s 的一個信號被提供有一第一值，及因此參考源乂2提供一個 具有一對應值的參考電壓。藉由電晶體Q1、〇2形成的比 較器此時比較參考源的電壓與串聯電阻器仏上的電壓（或 者更精確地，與RS上之交流電壓的電壓峰值），及輸出一 130982.doc -14- 200948203 電流給藉由電容器Ci及電流源η形成的比較器。在一穩態 中’藉由電流源II提供的電流等於源於電晶體的電流。 電壓受控振盪器藉由積分器（的輸出電壓）驅動，經由回饋 效應這導致尚於該網路之共振頻帶的一振盪頻率，及因此 導致燈的關閉。在此情形中，串聯電阻器Rs上的電壓因此 與加熱電流成正比。因此，此時提供了控制加熱電流的一 回饋控制操作：藉由Q1、Q2形成的比較器比較串聯電阻 器Rs上的電壓與參考電壓V2,並驅動積分器與電壓受控振 © 盪器VC0以獲得一加熱電流’該加熱電流導致電阻器Rs上 與V2瞬時值相配的一個電壓。 現將在燈被點亮及操作（即開啓）之情形下描述根據圖3 之電路的操作。在第二時間週期内（如參考圖1描述的），在 輸入S處的驅動信號提供一較第一時間週期之不同的值。 作為一項實例’在驅動輸入S處的驅動信號可具有數位低 及尚位準，舉例而言，具有數位低位準的一信號指示第一 時間週期及將電壓源V2設定至第一參考電壓值，而具有高 ® 位準的一信號將電壓源V2設定至第二參考電壓值。由於參 考源的第二電壓值，藉由Ql、Q2形成的比較器將驅動積 • 分器及從而驅動電壓受控振盪器vco以改變（在此實例 中.降低）振盪頻率’及因此改變燈經由網路被驅動所用 的頻率。頻率達到網路的共振頻帶，燈上的電壓將增加而 導致其點亮。在缺乏電晶體Q3、電容器Cv及電阻器R3 時，現將藉由電路來控制通過燈的總電流（即，加熱燈電 極之電極電流與弧電流的總和），引起跨串聯電阻器Rs的 130982.doc 15 200948203 交流電壓來平衡電壓源的輸出，因此，一個單控制電路控 制燈的電極加熱電流及弧電流兩者。 可藉由在輸入s處所提供之信號的重複頻率而决定燈的 脈衝重複頻率，從而容許燈脈衝與一外部源的同步，這在 許多應用中可能是有用的’舉例而言’藉由該燈照明之一 顯示器的影像重複頻率。 - 為了提供該燈的一受控光輸出，期望在第二時間週期内 (即，當該燈點亮及導通時）控制弧電流（而非控制弧電流與 Ο 加熱電流的總和）。在一實施例中，此藉由電晶體Q3、電 容器Cv及電阻器R3來提供。在第二時間週期内，藉由在 輸入S處之信號的一個適當值而切換電晶體Q3到一非導電 狀態，這將提供一個附加信號給藉由及q2所形成之比 較器的輸入。由於電容器Cv的一個終端連接至燈的高壓側 電極，跨電容器Cv與電阻器R3之串聯連接的電壓將很大 程度上對應於跨電容器Cr(其連接於燈電極之間）與串聯電 阻器Rs的電壓。由於電極加熱電流被引導通過電容器&， ® 跨電容器Cr的電壓將與加熱電流有關。通過電容器Cv的電 流可因此形成加熱電流的一個指示。在一實務實施中，電 ' 谷器Cv的電容可選擇為低於Cr之電容，導致通過Cv的電 *IL低於加熱電流。為了補償，串聯連接於參考電壓源與Q 1 射極（Q1射極形成比較器的一個輸入）之間之電阻器R2的值 可選擇為滿足方程式Cr*Rs=Vc*R2，以獲得跨R2的一個電 廢，該電壓提供電極加熱電流之指示。由於在此實施例中 提供電極加熱電流之指示的電壓被添加到參考電壓源，根 130982.doc 200948203 據該回饋控制系統該電壓將被有效地從跨串聯電阻器Rs的 電壓中減去。因此代表電極加熱電流的電壓將從代表燈總 電流（之近似值）的電壓中減去，這提供了此等電流之間之 差異、即弧電流（之近似值）的控制。因此，如參考圖3所描 述之控制電路現在容許用一個簡單、單控制系統來控制第 一（即加熱）時間週期内的加熱電流及控制第二（即燈的點亮 與操作）時間週期内的弧電流。 參考源的輸出值（諸如輸出電壓）可作出變動以使在燈之 ® 脈衝式操作的脈衝寬度與電極加熱電流之間建立一種關 係：在具有較低脈衝寬度情况下，電極加熱電流由於弧電 流而趨於減小。這可藉由參考源之輸出值的一對應變化而 抵消’以増加電極電流從而保持電極溫度為固定。此外， 當燈導通時’參考源的輸出值可用於設定弧電流。從而， 燈的強度可因此藉由加熱/操作循環之作用時間循環中的 變化，及/或參考源輸出值中的變化以改變期望娘電流而 設定。弧電流可改變的應用可包括帶有雙脈衝方案的掃描 ® 背光系統，其中兩種脈衝以不同電流數量級使用。 【圖式簡單說明】 - 圖1根據本發明之一實施例描繪了螢光燈之驅動曲線的 一項實例； 圖2根據本發明之一實施例插繪了 一種用於控制螢光燈 之控制電路的方塊示意圖；及 圖3根據本發明之一實施例描繪了 一種控制電路的電路 簡圖。 130982.doc -17· 200948203 【主要元件符號說明】200948203 IX. Description of the Invention: [Technical Field] The present invention relates to a method and circuit for pulsed operation of a fluorescent lamp, a ballast including the same, and a circuit and the same Assembly. [Prior Art] US 5 907 222 discloses a controller for driving a fluorescent lamp. The controller includes an arc current regulator and a filament current regulator. When the lamp is operated in a pulsed or dimmed manner, the electrodes of the lamp must be heated to maintain the lamp in an operational operating area and to ensure illumination of the lamp. A separate filament current regulator is also provided which provides filament current to heat the electrodes of the lamp and i separates the arc current regulator to control the arc current and the voltage across the lamp. Regardless of the advantages of such a controller, 'there must be a rather complicated circuit' because of the fact that it provides a double control, which adds complexity to the circuit and may adversely affect _ or more design parameters. , such as cost, volume, part count, and so on. SUMMARY OF THE INVENTION The object of the present invention is to control the heating of the glory lamp electrode and the lighting and arc current of the lamp by a simple control circuit. The above object can be achieved by a method for pulsed operation of a fluorescent lamp, the method comprising: - providing a power signal to the lamp via a network having a frequency dependent transfer function; During a heating portion of the pulse repetition time period, controlling a frequency of the source 130982.doc 200948203 source signal in a first frequency band to provide an electrode current to the lamp to heat an electrode of the lamp; and - in the pulse During an operational portion of the repeating time period, the frequency of the power signal is controlled to be within a second frequency band to illuminate the lamp and provide arc current and electrode current to the lamp. Further, in one aspect of the invention, the above object can be achieved by a circuit for pulsed operation of a fluorescent lamp, the circuit comprising: - a power signal generator for generating a power signal Providing power to the xenon lamp, a network having a frequency dependent transfer function, the network being coupled to the power signal generator and for providing the power signal to the lamp; and a light controller for Driving the power signal generator, the light controller has a set input to receive a set input signal and is configured to: when the set input is at a first level, control the power signal generator to the power signal a frequency set in a first frequency band to provide an electrode current to the lamp to heat an electrode of the lamp; and ❿ when the set input is at a second level, the power signal generator is controlled to power the The frequency of the signal is set in a second frequency band to illuminate the lamp and provide an arc current and electrode current to the lamp. - According to the invention, the lamp drive frequency will be alternately set in a first frequency band and - in a second frequency band. In this first frequency band, the voltage on the lamp is relatively low due to the frequency dependence of the resonant network. Because of this low voltage, an arc in the lamp will not be maintained 'and therefore the lamp will turn off. The current flowing through the electrodes via the network will only heat the electrodes. When the frequency is brought to the second frequency band, the voltage on the lamps 130982.doc -8 - 200948203 will increase, which will cause the lamp to illuminate. The lamp will remain on during the second time period and will be turned off when the frequency changes at the end of the second time period, because the voltage on the lamp is reduced due to the change of frequency at that moment, therefore, the pulse operation of the lamp The heating of the electrodes can be achieved with a single drive signal. In addition, a single drive circuit can provide current for two time periods. (iv) A single control circuit is provided. As an example, the network may include a "vibration network" such as an inductor 'capacitor resonance network, the first frequency band being selected to be outside of one of the resonant frequency bands of the resonant network, and the second frequency band being selected as _ Within the eight-vibration band, by resonance, an effective increase in the amount of electricity (such as voltage) driving the lamp can be obtained. This allows the second band to be set in the resonant band. The other embodiments are also feasible. As an example, the second frequency band may be lower than a frequency band of such a resonant network. In its embodiment, the network may include any suitable network having one or more parts exhibiting frequency dependence. Road, such as one of more capacitors, one of more inductors, one of transformers, etc. In the circuit towel according to the present invention, a set-input can be provided, and the number of the input input is used to set the frequency of the power signal. Controlling in the first or second frequency band such that 'on and off of the lamp can be controlled by an external signal, - this allows for the pulsed operation of the lamp to be synchronized with, for example, an external source. In an embodiment, Controlled heating The flow, and thus the stability of the lamp electrode, during the heating portion of the pulse repetition period, a reference source is set to the 帛-output value, a signal flowing through one of the electrode currents of the lamp and the reference source The first output value is compared, and wherein the frequency of the power signal is adjusted based on a comparison between the signal representative of the electrode current and the first output value 130982.doc 200948203 of the reference source. In an embodiment, In order to control the arc current, during the operational portion of the pulse repetition period, the reference source is set to a second output value, and a signal representative of the electrode current is subtracted from a signal representative of the total current flowing through the lamp, the subtraction result is The second output value of the reference source is compared, and wherein the frequency of the power supply signal is adjusted based on a comparison between the subtraction result and the second value of the reference source. Thus, by representing the total current through the lamp A signal minus a signal representative of the electrode current 'obtains an indication of the arc current, which can be used to control and/or monitor the arc current, and thus control and/or monitor the light of the lamp By changing the ratio of the operating portion and the heating portion of the pulse repetition period, and changing the first output value of the reference source according to the change ratio, so that a desired electrode current is adapted to the duration of the change of the heating portion to the pulse cycle Variations in the duty cycle of the electrode heating portion can compensate for electrode heating to thereby maintain a desired electrode temperature. With the circuit according to the present invention, a plurality of similar preferred embodiments for achieving the same or similar climbing effects as described above can be provided. In accordance with a preferred embodiment of the circuit of the present invention, the controller can be formed by a simple, cost effective circuit, wherein the controller includes a pair of bipolar transistors, the bipolar transistors The respective bases are electrically connected, and the emitters of the bipolar transistors are electrically connected to a reference source and electrically connected to a signal representative of a total current flowing through the lamp, and one of the transistors is electrically charged Connect to an integrator or the controller. In addition, in order to allow the controller to adjust the frequency of the power signal, the source 130982.doc 200948203 source signal generator can include a controlled oscillator whose frequency can be controlled by an electrical input of the oscillator. The output of the integrator is electrically coupled to the controlled oscillator for providing the electrical input. Further, when the network includes an electrode current supply capacitor connected between the electrodes of the lamp, the controller may include a capacitor, one of the terminals of the capacitor being connected to a driving side electrode of the lamp, the capacitor Providing a current to provide a signal representative of the heating current through the current: the inventors have recognized that by connecting one terminal of a capacitor to the driving side electrode (ie, the "thermal" side of the lamp 'There is a high voltage applied to the lamp by the network here and the other terminal of the capacitor is held at a low voltage similar to the voltage of the other electrode of the lamp to obtain an electrode heating current (which also flows through the current supply) One indication of the electrode) 'the current through the capacitor provides an indication of the current through the electrodes of the lamp. The invention further comprises a ballast for driving a fluorescent lamp, the ballast comprising a circuit in accordance with the invention. Still further, the invention comprises an assembly of a fluorescent lamp and an electrical circuit according to one of the inventions. [Embodiment] FIG. 1 is a graph showing a lamp driving frequency versus time. The time is plotted along the horizontal axis, and the lamp driving power signal pS is drawn along the vertical axis. As shown in Figure 1, the lamp is driven by an AC power signal whose frequency changes over time. Note that the amplitude or voltage on the lamp may also change due to changes in frequency' such as the frequency dependence of the network via which the lamp is driven, as will be explained in more detail below. Note that in this example, the network 130982.doc •11- 200948203 includes a resonant network, as will be outlined in more detail below. As depicted in FIG. ,, the lamp driving signal in this embodiment displays a first time period τι, wherein the lamp driving signal has a first frequency (more generally: it causes the lamp to drive the nickname in the first a frequency range or a frequency band), and a second time period T2, wherein the lamp driving signal has a second frequency (more generally, wherein the lamp driving signal is in a second frequency range or frequency band, where In an example, during the first time period T1, the lamp driving frequency is higher than a resonance frequency of the network, and in the second time period ,, the lamp driving frequency is within a resonance frequency band of the network. During the first cycle, the voltage on the lamp is relatively low due to the frequency dependence of the resonant network. Because of this low voltage, an arc in the lamp will not be maintained, and therefore the lamp will be turned off. The current will only heat the electrodes. When the frequency is lowered and brought to the resonant frequency band of the lamp, the voltage on the lamp will increase, which will cause the lamp to illuminate. The lamp remains on during the second time period, and Two time period The beam will be turned off as the frequency increases, because at that moment the voltage on the lamp is reduced due to the change in frequency. T1 & T2 together form a pulse repetition time period ® Τ, as depicted in Figure 1. In this document, the term The resonant frequency band is understood to be a frequency band in which the network exhibits a certain degree of resonance, for example. 5% or more of the peaks reach an appropriate electrical transfer characteristic. As depicted in Figure 3, the network may include A combination of an inductor and a capacitor. Alternatively, the network can include a combination of a transformer and a capacitor. Any other network can be used. In the example depicted in Figure 3, the network includes a bypass capacitor. Cr 'the bypass capacitor is connected between the electrodes on the opposite side of the lamp. The heating current flowing through the electrodes such as shai is first guided from the electrodes by the 130982.doc •12·200948203 The second of the electrodes. The network of Figure 3 further comprises an inductor L. The Cs forms a light-sense capacitor that is connected in series with the inductor L to allow the single-ended (i.e., single supply voltage) of the lamp to be driven. 2 A block diagram of a circuit for driving a fluorescent lamp TL. A power source 10 (such as a main power source, a main power adapter...a battery or a rectifying main power source) supplies power to a power supply circuit 2〇, the power supply circuit 2〇 The power supply signal PS is supplied to the lamp TL by the network 30. The power supply circuit 20 operates the power supply supplied thereto by the power supply 10 to generate an AC lamp drive current at the lamp drive frequency ©. A half bridge or other suitable switching element is included. Further, the power circuit 2A can include an oscillator to generate a frequency of the lamp driving current. The oscillator can include a controlled oscillator that can be controlled by the lamp controller 40. In this example, the lamp controller is provided with a feedback signal fb representative of the current through lamp TL. Controller 40 generates a control signal to control power supply circuit 2, for example by providing a control 彳s number (such as A voltage is applied to a controlled oscillator (such as a voltage controlled oscillator) of the power supply circuit 2〇. The controller is further provided with a set input S, responding to an appropriate signal at the set input S and being provided with a feedback signal FB which drives the power circuit 20 to form a feedback control system to operate the lamp. By supplying an appropriate signal to the set input, the frequency of the power signal supplied to the lamp can be changed because the feedback loop will settle to a corresponding frequency in response to a pair of signals at the set input S. In some embodiments, the 'set input S can be provided with an analog signal to form a set point signal, while in other embodiments, the set input can form a switch input to provide a signal such as a digital or similar signal to The internal 130982.doc -13.200948203 reference of the controller is set to an appropriate value under the control of the input signal of the set input. In such embodiments, in an internal reference, such as a reference voltage source may be provided 'an input value of the reference voltage source is controlled by an input signal at a set input s, for example, to make the reference voltage source different The value varies between 'to thereby stabilize the feedback control circuit at different frequencies. In such an embodiment, the set input may thus be provided with a signal having a first level during the first time period and a second level during the second time period, thereby A power signal of Φ of the frequency pattern as depicted in Figure 1 drives the lamp. Figure 3 shows a more detailed view of one embodiment of a circuit in accordance with the present invention. The power supply circuit as depicted in Figure 2 includes a voltage controlled oscillator vc and a half bridge, which is schematically indicated by Vhb. The network 30 includes an inductor L, a capacitor Cr to bridge the electrode 'and a coupling capacitor Cs, the function of which has been described above. A feedback signal is generated by a series resistor R which provides a feedback voltage proportional to the total current of the lamp. The total current of the lamp is the electrode current supplied via the capacitor Cr and the arc current when the lamp is turned on. In this example, controller 40 includes a comparator formed by transistors Qi, q2, an integrator formed by capacitor Ci and current source II. The reference signal - is generated by a voltage source V2 which is controlled by a signal to be supplied at the wheel 8 . During the heating portion of the pulse repetition period, a signal at s is supplied with a first value, and thus reference source 乂2 provides a reference voltage having a corresponding value. The comparator formed by the transistors Q1, 〇2 compares the voltage of the reference source with the voltage across the series resistor ( (or more precisely, the voltage peak of the AC voltage on the RS), and outputs a 130982.doc -14- 200948203 Current is supplied to the comparator formed by capacitor Ci and current source η. In a steady state, the current supplied by current source II is equal to the current from the transistor. The voltage controlled oscillator is driven by the (output voltage of the integrator), which causes an oscillating frequency that is still in the resonant frequency band of the network via the feedback effect, and thus causes the lamp to turn off. In this case, the voltage across the series resistor Rs is therefore proportional to the heating current. Therefore, a feedback control operation for controlling the heating current is provided at this time: the comparator formed by Q1 and Q2 compares the voltage across the series resistor Rs with the reference voltage V2, and drives the integrator and the voltage controlled oscillator VC0. A heating current is obtained which causes a voltage on the resistor Rs that matches the instantaneous value of V2. The operation of the circuit according to Figure 3 will now be described in the context of a light being illuminated and operational (i.e., turned on). During the second time period (as described with reference to Figure 1), the drive signal at input S provides a different value than the first time period. As an example, the driving signal at the driving input S may have a digital low level, for example, a signal having a digital low level indicates a first time period and the voltage source V2 is set to a first reference voltage value. And a signal with a high ® level sets the voltage source V2 to a second reference voltage value. Due to the second voltage value of the reference source, the comparator formed by Q1, Q2 will drive the product divider and thereby drive the voltage controlled oscillator vco to change (in this example, lower) the oscillation frequency 'and thus change the lamp The frequency used to be driven via the network. When the frequency reaches the resonant frequency band of the network, the voltage on the lamp will increase and cause it to illuminate. In the absence of transistor Q3, capacitor Cv, and resistor R3, the total current through the lamp (ie, the sum of the electrode current and the arc current of the heated lamp electrode) is now controlled by the circuit, causing 130982 across the series resistor Rs. .doc 15 200948203 AC voltage to balance the output of the voltage source, therefore, a single control circuit controls both the electrode heating current and the arc current of the lamp. The pulse repetition frequency of the lamp can be determined by the repetition frequency of the signal provided at input s, thereby allowing the lamp pulse to be synchronized with an external source, which may be useful in many applications by way of example The image repeat frequency of one of the illuminated displays. - In order to provide a controlled light output of the lamp, it is desirable to control the arc current (rather than the sum of the control arc current and the 加热 heating current) during the second time period (i.e., when the lamp is illuminated and turned on). In one embodiment, this is provided by transistor Q3, capacitor Cv, and resistor R3. During the second time period, transistor Q3 is switched to a non-conducting state by an appropriate value of the signal at input S, which provides an additional signal to the input of the comparator formed by q2. Since one terminal of the capacitor Cv is connected to the high-voltage side electrode of the lamp, the voltage across the series connection of the capacitor Cv and the resistor R3 will largely correspond to the cross-capacitor Cr (which is connected between the lamp electrodes) and the series resistor Rs. Voltage. Since the electrode heating current is directed through the capacitor &, the voltage across the capacitor Cr will be related to the heating current. The current through capacitor Cv can thus form an indication of the heating current. In a practical implementation, the capacitance of the electric 'CV' can be selected to be lower than the capacitance of Cr, resulting in the electric current *IL passing through Cv being lower than the heating current. To compensate, the value of resistor R2 connected in series between the reference voltage source and the Q 1 emitter (an input of the Q1 emitter forming comparator) can be selected to satisfy the equation Cr*Rs=Vc*R2 to obtain a cross-R2 An electrical waste that provides an indication of the electrode heating current. Since the voltage providing the indication of the electrode heating current in this embodiment is added to the reference voltage source, the root 130982.doc 200948203 will be effectively subtracted from the voltage across the series resistor Rs according to the feedback control system. Thus the voltage representative of the electrode heating current will be subtracted from the voltage representative of the lamp's total current (approximate value), which provides control of the difference between these currents, i.e., the arc current (approximate value). Thus, the control circuit as described with reference to Figure 3 now allows for a simple, single control system to control the heating current during the first (i.e., heating) time period and control the second (i.e., the lighting and operation of the lamp) time period. Arc current. The output value of the reference source (such as the output voltage) can be varied to establish a relationship between the pulse width of the pulsed operation of the lamp and the electrode heating current: in the case of a lower pulse width, the electrode heating current is due to the arc current And tend to decrease. This can be counteracted by a corresponding change in the output value of the reference source to apply the electrode current to keep the electrode temperature constant. In addition, the output value of the reference source can be used to set the arc current when the lamp is turned on. Thus, the intensity of the lamp can thus be set by a change in the duty cycle of the heating/operation cycle, and/or by a change in the reference source output value to change the desired cathode current. Applications where arc current can be varied can include a scanning ® backlight system with a dual pulse scheme where two pulses are used in different current orders of magnitude. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an example of a driving curve of a fluorescent lamp according to an embodiment of the present invention; FIG. 2 is a diagram for controlling control of a fluorescent lamp according to an embodiment of the present invention. A block diagram of a circuit; and FIG. 3 depicts a simplified circuit diagram of a control circuit in accordance with an embodiment of the present invention. 130982.doc -17· 200948203 [Key component symbol description]
10 電源 20 電源電路 30 網路 40 控制器 Ci 電容器 Cr 旁路電容器 Cs 耦合電容器 Cv 電容器 11 電流源 L 電感器 Q1-Q3 電晶體 R1-R4 電阻器 Rs 串聯電阻器 S 設定輸入 TL 螢光燈 VI、V2 電壓源 vco 電壓受控振盪器 Vhb 半橋接器 130982.doc -18-10 Power supply 20 Power supply circuit 30 Network 40 Controller Ci Capacitor Cr Bypass capacitor Cs Coupling capacitor Cv Capacitor 11 Current source L Inductor Q1-Q3 Transistor R1-R4 Resistor Rs Series resistor S Set input TL Fluorescent VI , V2 voltage source vco voltage controlled oscillator Vhb half bridge 130982.doc -18-