201240518 Λ»_；Αΐ/ϋν07 37150twf.doc/n 六、發明說明： 【發明所屬之技術領域】 本發明是有關於一種光源系統，且特別是有關於一種 發光二極體的光源系統與驅動方法。 【先前技術】 近年來，隨著半導體科技蓬勃發展，攜帶型電子產品 及平面顯示器產品也隨之興起。而在眾多平面顯示器的類 型當中，液晶顯示器（liquid crystal display, LCD )基於其 低電壓操作、無輻射線散射、重量輕以及體積小等優點， 隨即已成為各顯示器產品之主流。一般而言，由於液晶顯 示面板本身並不具備自發光的特性，因此必須在液晶顯示 面板的下方放置背光模組，藉以提供液晶顯示面板所需的 (背）光源。 傳統的背光模組大致可以分為兩類，其一係由冷陰極 管（cold cattiode fluorescent lamp，CCFL )所組成的背光模 組，而另一則由發光二極體（light emitting diode，LED )所 組成的背光模組。其中，由於發光二極體背光模組可以提 升液晶顯示器的色域（color gamut)，故而現今各家面板 業者大多以發光二極體背光模組來取代冷陰極管背光模 組。 發光二極體背光模組具有多組並列在一起的發光二 極體串（LED strings)，而且每一發光二極體串係由多顆 串接在一起的發光二極體所組成。實務上，每一發光二極 4 201240518 AU1011007 37150twf.doc/n 體串會操作在一直流輸出電壓（DC output voltage)下，並 且受驅動晶片（driver 1C )的驅動而發光。然而，由於每 一發光二極體串係會透過連接器（connector)而與驅動晶 片連接在一起，故而在進行靜電放電測試（ESD test)時， 較容易產生失敗的靜電放電測試結果。 而為了要解決這樣的問題，一般可以在每—發光二極 體串與驅動晶片之外部間額外加入瞬態電壓抑制二極體 (transient voltage suppression diode, TVS diode )，藉以提 升靜電放電測試結果的成功率以及實現靜電放電的防護。 然而，缺點就是因應現今大尺寸面板的需求，發光二極體 背光模組内所配置的發光二極體串之總數就會越多，故而 需額外加入的瞬態電壓抑制二極體之數量就會越多，進而 增加製作成本。 【發明内容】 有鑒於此’本發明提出一種光源系統與發光二極體驅 動方法，藉以有效地改善先前技術所述及的問題。 本發明一實施例提供一種光源系統，其包括發光二極 體模組與驅動單元。發光二極體模組具有至少一發光二極 體串，且所述發光二極體串操作在一直流輸出電壓下。驅 動單元耦接發光二極體模組，用以提供所述直流輸出電 壓。其中，驅動單元更根據一設定訊號以驅動所述發光二 極體串，並且反應於所述發光二極體串之壓降與一預設參 考電壓的比較而決定是否提供一靜電放電路徑。 丨 X v a ▲ v 07 37150twf.doc/n 於本發明的-實施例中，驅動單元包括升降壓線路、 驅動器’錢靜電放電單元。其巾，升降壓線路偏妾所述 發光二極體串的陽極’用以接收—直流輸人電壓，並對所 述直流輸人電壓進行升壓或降壓處理後而產生所述直流輸 出電壓。驅動器耦接於所述發光二極體串的陰極與接地電 位之間，用以根據所述設定訊號以驅動所述發光二極體 串，並據以提供一回授訊號給升降壓線路，從而使得升降 壓線路，應於所述回授訊號以調整所述直流輸出電壓。靜 電放電單元祕所述發光二極體串的陰極，用以比較所述 發光二極體串的壓降與所述預設參考電壓，藉以決定是否 提供所述靜電放電路徑。 本發明另一貫施例提供一種適用於驅動至少一發光 二極體串的發光二極體驅動方法，其包括：提供一直流輸 出電壓至所述發光二極體串；根據—設定訊號以驅動所述 發光二極體串；以及反應於所述發光二極體串之壓降與預 設參考電壓的比較而決定是否提供靜電放電路徑。 於本發明的一實施例中，當比較出所述發光二極體串 之壓降大於所述預設參考電壓時，則提供所述靜電放電路 徑。反之，當比較出所述發光二極體串之壓降小於所述預 設參考電壓時，則停止提供所述靜電放電路徑。 〇基於上述，本發明主要是在用以驅動發光二極體串的 驅動單元（可視為驅動晶片）内直接配置有比較功能的靜 電放電單元，藉以在有靜電放電事件發生時，提供一條靜 電放電路徑以快速宣洩由靜電放電事件所引發的靜電放電 6 201240518 AU1011〇〇7 37150twf.doc/n 電流。如此一來’由於具有比較功能的靜電放電單元可以 直接配置在驅動晶片内，故而相較於以往的作法（亦即額 外加入瞬態電壓抑制二極體的方式），不但可以降低整體 的製作成本’而且還可以實現靜電放電的防護。 應瞭解的是’上述一般描述及以下具體實施方式僅為 例示性及闡釋性的’其並不能限制本發明所欲主張之範圍。 【實施方式】 現將詳細參考本發明之示範性實施例，在附圖中說明 所述示範性實施例之實例。另外，凡可能之處，在圖式及 實施方式中使用相同標號的元件/構件代表相同或類似部 分。 圖1繪示為本發明一實施例之光源系統（light source system) 10的示意圖。請參照圖},本實施例之光源系統 10可以為適用於液晶顯示系統（LCD system )當中的發光 一極體背光模組（LED backlight module )，但並不限制於 此且其包括有發光一極體模組（LED module) 101與驅 動單元（driving unit) 103。其中，發光二極體模組1〇1具 有至少一組由多顆發光二極體所串接而成的發光二極體串 (LED string) LED ’且此發光二極體串LED係操作在直 流輸出電壓（DC output voltage) Vout 下。 驅動單元103耦接發光二極體模組1〇1，用以提供直 流輸出電壓Vout至發光二極體串LED。另外，驅動單元 103更可以根據由系統端（例如時序控制器，但並不限制 201240518 AU1U11U07 37150twf.doc/n 於此）所提供的設定訊號（setting signal) ST而產生脈動 電流訊號（pulsation current signal)以驅動發光二極體串 LED，並且反應於發光二極體串LED之壓降（voltage drop) VDN 與預設參考電壓（predetermined reference voltage) Verf的比較而決定是否提供靜電放電路徑（esd path)以 宣洩由靜電放電事件（ESD event)所引發的靜電放電電流 (ESD current)。 於本實施例中，驅動單元103可以為一驅動晶片 (driver 1C)，且其包括升降塵線路（b〇〇st-buck circuit) 105、驅動器（driver) 107，以及靜電放電單元（ESD unit) 109。其中’升降壓線路i〇5耦接發光二極體串LED的陽 極（anode ) Ad ’用以接收直流輸入電壓（DC input voltage ) Vin，並對直流輸入電壓Vin進行升壓或降壓處理 (boost/buck processing )後而產生直流輸出電壓v〇ut。亦 即’當直流輸入電壓Vin小於發光二極體串LED所需的操 作電壓時’則升降壓線路105會對直流輸入電壓Vin進行 升壓處理’藉以產生並提供合適的直流輸出電壓Vout給發 光二極體串LED ;反之，當直流輸入電壓vin大於發光二 極體串LED所需的操作電壓時，則升降壓線路1〇5會對直 流輸入電壓Vin進行降壓處理，藉以產生並提供合適的直 流輸出電壓Vout給發光二極體串LED。 驅動器107耦接於發光二極體串LED的陰極 (cathode) Cd 與接地電位（ground p0tentiai)之間，用以 根據由系統端（例如時序控制器，但並不限制於此）所提 8 201240518 AU1011007 37150twf.doc/n 供的設定訊號ST而對應地產生脈動電流訊號以驅動發光 二極體串LED發光’並據以提供回授訊號（feedback signal) FB給升降壓線路103 ’從而使得升降壓線路1〇3反應於回 授§fl ?虎FB以调整直流輸出電壓v〇ut。更清楚來說，升降 壓線路103可以反應於回授訊號FB而採用例如脈寬調變 (PWM )的方式來控制/調整其所提供的直流輸出電壓 Vout大小，藉以致使所提供的直流輸出電壓v〇ut可以與 預期的設定訊號ST —致。 靜電放電單元109耦接發光二極體串LED的陰極 Cd，用以比較發光二極體串LED的壓降VDN與預設參考 電壓Vref’藉以決定是否提供靜電放電路徑。更清楚來說， 圖2綠示為本發明一實施例之靜電放電單元1〇9的示意 圖。請合併參照圖1與圖2，靜電放電單元1〇9包括比較 态（comparator) CMP 與開關（switch) SW。其中，比較 器CMP用以比較發光二極體串LED的壓降VDN與預設 參考電壓Vref’藉以輸出第一比較訊號CS1或第二比較訊 號 CS2。201240518 Λ»_;Αΐ/ϋν07 37150twf.doc/n VI. Description of the Invention: [Technical Field] The present invention relates to a light source system, and more particularly to a light source system and a driving method for a light emitting diode . [Prior Art] In recent years, with the rapid development of semiconductor technology, portable electronic products and flat panel display products have also arisen. Among the many types of flat panel displays, liquid crystal displays (LCDs) have become the mainstream of display products based on their low voltage operation, no radiation scattering, light weight and small size. In general, since the liquid crystal display panel itself does not have self-illuminating characteristics, it is necessary to place a backlight module under the liquid crystal display panel to provide a (back) light source required for the liquid crystal display panel. The conventional backlight modules can be roughly divided into two types, one is a backlight module composed of a cold cathode fluorescent lamp (CCFL), and the other is a light emitting diode (LED). A backlight module is formed. Among them, since the light-emitting diode backlight module can improve the color gamut of the liquid crystal display, most of the panel manufacturers today replace the cold cathode tube backlight module with a light-emitting diode backlight module. The LED backlight module has a plurality of LED strings arranged side by side, and each LED string is composed of a plurality of LEDs connected in series. In practice, each of the light-emitting diodes 4 201240518 AU1011007 37150twf.doc/n is operated under a DC output voltage and is driven by a driver 1C. However, since each of the light-emitting diode strings is connected to the driving wafer through a connector, it is easier to produce a failed electrostatic discharge test result when performing an ESD test. In order to solve such a problem, a transient voltage suppression diode (TVS diode) may be additionally added between each of the LED strings and the outside of the driving chip to improve the electrostatic discharge test result. Success rate and protection against electrostatic discharge. However, the disadvantage is that in response to the demand for large-sized panels today, the total number of LED strings disposed in the LED backlight module is increased, so that the additional transient voltage suppression diodes are required. The more will be, which will increase the production cost. SUMMARY OF THE INVENTION In view of the above, the present invention provides a light source system and a light emitting diode driving method, thereby effectively improving the problems described in the prior art. An embodiment of the invention provides a light source system including a light emitting diode module and a driving unit. The light emitting diode module has at least one light emitting diode string, and the light emitting diode string is operated at a DC output voltage. The driving unit is coupled to the LED module to provide the DC output voltage. The driving unit further drives the light emitting diode string according to a setting signal, and determines whether to provide an electrostatic discharge path in response to the voltage drop of the light emitting diode string and a preset reference voltage.丨 X v a ▲ v 07 37150 twf.doc/n In the embodiment of the invention, the drive unit comprises a buck-boost line, a driver 'money electrostatic discharge unit. The towel, the buck-boost line biases the anode of the light-emitting diode string to receive a DC input voltage, and the DC input voltage is boosted or stepped down to generate the DC output voltage. . The driver is coupled between the cathode of the LED string and the ground potential for driving the LED string according to the setting signal, and accordingly providing a feedback signal to the buck-boost line, thereby The buck-boost line is adapted to adjust the DC output voltage by the feedback signal. The electrostatic discharge unit is configured to compare the voltage drop of the light emitting diode string with the predetermined reference voltage to determine whether to provide the electrostatic discharge path. Another embodiment of the present invention provides a method for driving a light emitting diode suitable for driving at least one LED string, comprising: providing a DC output voltage to the LED string; and driving the device according to the setting signal Determining whether to provide an electrostatic discharge path by comparing a voltage drop of the light emitting diode string with a preset reference voltage. In an embodiment of the invention, when the voltage drop of the LED string is compared to be greater than the predetermined reference voltage, the electrostatic discharge path is provided. On the other hand, when the voltage drop of the light emitting diode string is compared to be smaller than the preset reference voltage, the supply of the electrostatic discharge path is stopped. 〇 Based on the above, the present invention mainly provides an electrostatic discharge unit having a comparison function directly in a driving unit (which can be regarded as a driving wafer) for driving a light emitting diode string, thereby providing an electrostatic discharge when an electrostatic discharge event occurs. The path to quickly vent the electrostatic discharge caused by the electrostatic discharge event 6 201240518 AU1011〇〇7 37150twf.doc/n current. In this way, because the electrostatic discharge unit with comparative function can be directly disposed in the driving chip, the overall manufacturing cost can be reduced not only in the conventional method (that is, the method of additionally adding a transient voltage suppression diode). 'And it can also protect against electrostatic discharge. It is to be understood that the above general description and the following specific embodiments are only illustrative and illustrative and are not intended to limit the scope of the invention. [Embodiment] Reference will now be made in detail to the exemplary embodiments embodiments In addition, wherever possible, the same reference numerals in the FIGS FIG. 1 is a schematic diagram of a light source system 10 according to an embodiment of the invention. Referring to FIG. 5 , the light source system 10 of the present embodiment may be an LED backlight module suitable for use in a liquid crystal display system (LCD system), but is not limited thereto and includes a light-emitting one. A LED module 101 and a driving unit 103 are provided. The light emitting diode module 1〇1 has at least one set of LED string LEDs connected in series by a plurality of light emitting diodes, and the LED array is operated in the LED string DC output voltage Vout. The driving unit 103 is coupled to the LED module 1〇1 for providing a DC output voltage Vout to the LED string LED. In addition, the driving unit 103 can generate a pulsation current signal according to a setting signal ST provided by a system end (for example, a timing controller, but does not limit 201240518 AU1U11U07 37150 twf.doc/n). ) to drive the LED string LED, and to determine whether to provide an ESD path by comparing the voltage drop VDN of the LED string with the predetermined reference voltage Verf (esd path) ) to vent the ESD current caused by the ESD event. In this embodiment, the driving unit 103 can be a driver 1C, and includes a buck-buck circuit 105, a driver 107, and an ESD unit. 109. The 'lower voltage line i〇5 is coupled to the anode of the LED string LED to receive the DC input voltage Vin and boost or step down the DC input voltage Vin ( Boost/buck processing) produces a DC output voltage v〇ut. That is, 'when the DC input voltage Vin is smaller than the operating voltage required for the LED string LEDs', the buck-boost line 105 will boost the DC input voltage Vin' to generate and provide a suitable DC output voltage Vout for illumination. The diode string LED; conversely, when the DC input voltage vin is greater than the operating voltage required for the LED string LED, the buck-boost line 1〇5 will step down the DC input voltage Vin to generate and provide suitable The DC output voltage Vout is given to the LED string LED. The driver 107 is coupled between the cathode Cd of the LED string and the ground potential (ground p0tentiai) for use according to the system end (eg, timing controller, but is not limited thereto) 8 201240518 AU1011007 37150twf.doc/n provides a setting signal ST to correspondingly generate a ripple current signal to drive the LED string LED to emit 'and to provide a feedback signal FB to the buck-boost line 103' to cause the buck-boost Line 1〇3 reacts to feedback §fl?hu FB to adjust DC output voltage v〇ut. More specifically, the buck-boost line 103 can be reacted to the feedback signal FB to control/adjust the magnitude of the DC output voltage Vout provided by, for example, pulse width modulation (PWM), thereby providing the supplied DC output voltage. V〇ut can be synchronized with the expected setting signal ST. The electrostatic discharge unit 109 is coupled to the cathode Cd of the LED array LED for comparing the voltage drop VDN of the LED string with the preset reference voltage Vref' to determine whether to provide an ESD path. More specifically, Fig. 2 is a schematic view showing an electrostatic discharge unit 1〇9 according to an embodiment of the present invention. Referring to FIG. 1 and FIG. 2 together, the electrostatic discharge unit 1〇9 includes a comparator CMP and a switch SW. The comparator CMP is configured to compare the voltage drop VDN of the LED string with the preset reference voltage Vref' to output the first comparison signal CS1 or the second comparison signal CS2.
另外’開關SW耦接比較器CMP，用以反應於比較器 CMP所輸出的第一比較訊號CS1或第二比較訊號CS2而 決定是否導通以形成靜電放電路徑。而且，開關SW可以 由N型電晶體（N-type transistor )所實現，例如N型金氧 半導體（NM0S)電晶體，但並不限制於此，故以下將開 關SW改稱為N型電晶體SW。其中，N型電晶體SW的 閘極（gate)耦接比較器CMP的輸出端，N型電晶體SW 201240518 Λ^χνιιν07 37150twf.doc/n 的源極（source)耦接至接地電位，而Ν型電晶體SW的 汲極（drain)則耦接發光二極體串LED的陰極Cd。 於本實施例中，當比較器CMP比較出發光二極體串 LED的壓降VDN小於預設參考電壓Vref時，則比較器 CMP會輸出第一比較訊號CS1 (例如邏輯低準位）。如此 一來，N型電晶體（開關）SW將反應於第一比較訊號CS1 而關閉（turn off)。另外，當比較器CMP比較出發光二 極體串LED的壓降VDN大於預設參考電壓Vref時，則比 較器CMP會輸出第二比較訊號CS2(例如邏輯高準位）。 如此一來，N型電晶體（開關）SW將反應於第二比較訊 號CS2而導通（turn on )。 更清楚來說，在光源系統10的運作期間，當未有靜 電放電事件發生時，由於發光二極體串LED的壓降VDN 並不會受靜電放電事件的影響而大幅度地抬升，所以此時 發光二極體串LED的壓降VDN會小於預設參考電壓 Vref。因此，比較器CMP就會輸出具有邏輯低準位的第一 比較訊號CS1以致使N型電晶體（開關）SW關閉。另一 方面’在光源系統10的運作期間，當有靜電放電事件發生 時，由於發光二極體串LED的壓降VDN會受到靜電放電 事件的影響而大幅度地抬升’所以此時發光二極體串led 的壓降VDN會大於預設參考電壓vref。因此，比較器CMP 就會輸出具有邏輯高準位的第二比較訊號CS2以致使N型 電晶體（開關）SW導通。 可見得，在光源系統1〇的運作期間，當有靜電放電 201240518 AU1011007 37150twf.doc/n 事件發生時，則比較器CMP會致使N型電晶體（開關） SW導通以形成/提供一條靜電放電路徑，進而快速宣由 靜電放電事件所引發的靜電放電電流esd_i至接地電位。 如此一來’即可保護驅動器107的内部元件（未繪示）， 進而得以與一般設計在驅動單元1〇3 (亦即驅動晶片）之 輸出入（I/O)的外部靜電放電防護元件（未繪示）—起實 現靜電放電的防護。此外，由於靜電放電單元1〇9可以直 接配置在驅動晶片内，所以相較於以往的作法（亦即額外 加入瞬態電壓抑制二極體的方式），更可以大幅地降低製 作成本。 基於上述實施例所揭示/教示的内容，圖3繪示為本發 明一實施例之發光二極體驅動方法的流程圖。請參照圖 3 ’本實施例之發光二極體驅動方法適於驅動至少一發光二 極體串’且其包括：提供直流輸出電壓至發光二極體串（步 驟S301);根據設定訊號以驅動發光二極體串（步驟 S303);以及反應於發光二極體串之壓降與預設參考電壓 的比較而決定是否提供靜電放電路徑（步驟S305)。 於本實施例中，當比較出發光二極體串之壓降大於預 設參考電壓時，則表示有靜電放電事件的發生，如此將需 提供靜電放電路徑，藉以宣洩由靜電放電事件所引發的靜 電放電電流；反之，當比較出發光二極體串之壓降小於預 設參考電壓時’則表示未有靜電放電事件的發生，如此將 需停止提供靜電放電路徑，藉以避免影響發光二極體串的 驅動。 201240518 AU1U11U07 37150twf.doc/n 综上所述，本發明主要是在用以驅動發光二極體串的 驅動晶片内直接配置有比較功能的靜電放電單元，藉以在 有靜電放電事件發生時，提供一條靜電放電路徑以快速宫 洩由靜電放電事件所引發的靜電放電電流。如此一來，'由 於具有比較功能的靜電放電單元可以直接配置在驅動晶片 内，故而相較於以往的作法（亦即額外加入瞬態電壓:制 二極體的方式），不但可以降低整體的製作成本，而且還 可以貫現靜電放電的防護。除此之外，任何設計、製造戈 以類似在驅動晶片内直接配置具有比較功能之靜電放電^ 元以實現靜電放電防護的手段，均屬於本發明所欲保護的 範 。 、口 雖然本發明已以實施例揭露如上，然其並非用以限定 本發明，任何所屬技術領域中具有通常知識者，在不 本發明之精神和範圍内，當可作些許之更動與潤飾，故本 發明之保護範圍當視後附之申請專利範圍所界定者為準。 另外，本發明的任一實施例或申請專利範圍 明所揭露之全部目的或優點或特點。此外，摘 題僅是用來辅助專利文件搜尋之用，並非用來限制本發^ 之權利範圍。 【圖式簡單說明】 下面的所附圖式是本發明的說明書的一部分，繪示了 本發明的示例實施例’所附圖式與說明書的描述一起說明 本發明的原理。 12 201240518 AU1011007 37150twf.doc/n 圖1繪示為本發明一實施例之光源系統10的流程圖。 圖2繪示為本發明一實施例之靜電放電單元109的示 意圖。 圖3繪示為本發明一實施例之發光二極體驅動方法的 流程圖。 【主要元件符號說明】 10 :光源系統 101 :發光二極體模組 103 :驅動單元 105 :升降壓線路 107 :驅動器 109 :靜電放電單元 LED :發光二極體串 CMP :比較器 SW (N型電晶體）：開關In addition, the switch SW is coupled to the comparator CMP for determining whether to conduct to form an electrostatic discharge path in response to the first comparison signal CS1 or the second comparison signal CS2 outputted by the comparator CMP. Moreover, the switch SW can be implemented by an N-type transistor, such as an N-type metal oxide semiconductor (NMOS) transistor, but is not limited thereto, so the switch SW is hereinafter referred to as an N-type transistor. SW. The gate of the N-type transistor SW is coupled to the output end of the comparator CMP, and the source of the N-type transistor SW 201240518 Λ^χνιιν07 37150twf.doc/n is coupled to the ground potential, and The drain of the type transistor SW is coupled to the cathode Cd of the LED array LED. In this embodiment, when the comparator CMP compares the voltage drop VDN of the LED string LED to be less than the preset reference voltage Vref, the comparator CMP outputs the first comparison signal CS1 (eg, a logic low level). As a result, the N-type transistor (switch) SW will turn off in response to the first comparison signal CS1. In addition, when the comparator CMP compares the voltage drop VDN of the LED string LED to be greater than the preset reference voltage Vref, the comparator CMP outputs a second comparison signal CS2 (e.g., a logic high level). As a result, the N-type transistor (switch) SW will turn on in response to the second comparison signal CS2. More specifically, during the operation of the light source system 10, when no electrostatic discharge event occurs, the voltage drop VDN of the LED string LED is not greatly affected by the electrostatic discharge event, so this is The voltage drop VDN of the LED string LED will be less than the preset reference voltage Vref. Therefore, the comparator CMP outputs a first comparison signal CS1 having a logic low level to cause the N-type transistor (switch) SW to be turned off. On the other hand, during the operation of the light source system 10, when an electrostatic discharge event occurs, the voltage drop VDN of the LED string LED is greatly increased due to the electrostatic discharge event. The voltage drop VDN of the body string led will be greater than the preset reference voltage vref. Therefore, the comparator CMP outputs a second comparison signal CS2 having a logic high level to cause the N-type transistor (switch) SW to be turned on. It can be seen that during the operation of the light source system, when the electrostatic discharge 201240518 AU1011007 37150twf.doc/n event occurs, the comparator CMP causes the N-type transistor (switch) SW to be turned on to form/provide an electrostatic discharge path. And quickly declare the electrostatic discharge current esd_i caused by the electrostatic discharge event to the ground potential. In this way, the internal components (not shown) of the driver 107 can be protected, and the external electrostatic discharge protection component (I/O) which is generally designed to be input (I/O) of the driving unit 1〇3 (ie, the driving wafer) can be Not shown) - to achieve protection against electrostatic discharge. Further, since the electrostatic discharge cells 1〇9 can be directly disposed in the driving wafer, the manufacturing cost can be greatly reduced as compared with the conventional method (i.e., the method of additionally adding a transient voltage suppressing diode). Based on the disclosure/teaching of the above embodiments, FIG. 3 is a flowchart of a method for driving a light emitting diode according to an embodiment of the present invention. Referring to FIG. 3, the LED driving method of the present embodiment is adapted to drive at least one LED string ' and includes: providing a DC output voltage to the LED string (Step S301); driving according to the setting signal a light emitting diode string (step S303); and determining whether to provide an electrostatic discharge path by comparing a voltage drop of the light emitting diode string with a preset reference voltage (step S305). In this embodiment, when comparing the voltage drop of the LED string is greater than the preset reference voltage, it indicates that an electrostatic discharge event occurs, so that an electrostatic discharge path is required to vent the static electricity caused by the electrostatic discharge event. Discharge current; conversely, when comparing the voltage drop of the LED string is less than the preset reference voltage, it means that there is no electrostatic discharge event, so it will be necessary to stop providing the ESD path to avoid affecting the LED string. drive. 201240518 AU1U11U07 37150twf.doc/n In summary, the present invention mainly provides an electrostatic discharge unit with a comparison function directly in a driving wafer for driving a light emitting diode string, thereby providing a static discharge event. The ESD path is used to quickly vent the ESD current caused by an ESD event. In this way, because the electrostatic discharge unit with comparative function can be directly disposed in the driving chip, compared with the conventional method (that is, the additional transient voltage: the diode is formed), not only can the overall The cost of production, but also the protection of electrostatic discharge. In addition, any means for designing and fabricating an electrostatic discharge device having a comparative function directly in the driving wafer to achieve electrostatic discharge protection is an embodiment of the present invention. Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any person skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of the invention is defined by the scope of the appended claims. In addition, all of the objects or advantages or features disclosed in any embodiment or application of the present invention are disclosed. In addition, the topic is only used to assist in the search of patent documents, and is not intended to limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The following drawings are a part of the specification of the invention, and illustrate the embodiments of the invention 12 201240518 AU1011007 37150twf.doc/n FIG. 1 is a flow chart of a light source system 10 according to an embodiment of the present invention. 2 is a schematic view of an electrostatic discharge unit 109 according to an embodiment of the present invention. FIG. 3 is a flow chart showing a driving method of a light emitting diode according to an embodiment of the present invention. [Main component symbol description] 10: Light source system 101: Light-emitting diode module 103: Driving unit 105: Buck-Boost line 107: Driver 109: Electrostatic discharge unit LED: Light-emitting diode string CMP: Comparator SW (N type Transistor): switch
Vin :直流輸入電壓Vin : DC input voltage
Vout :直流輸出電壓 ST :設定訊號 FB :回授訊號 VDN :發光二極體串的壓降Vout : DC output voltage ST : setting signal FB : feedback signal VDN : voltage drop of the LED string
Vref :預設參考電壓 CS1 :第一比較訊號 CS2 :第二比較訊號 13 201240518 /\uiunu07 37150twf.doc/nVref : preset reference voltage CS1 : first comparison signal CS2 : second comparison signal 13 201240518 /\uiunu07 37150twf.doc/n
Ad :發光二極體串的陽極 Cd :發光二極體串的陰極 ESD_I :靜電放電電流 S301〜S305 :本發明一實施例之發光二極體驅動方法 的流程圖各步驟Ad: anode of the light-emitting diode string Cd: cathode of the light-emitting diode string ESD_I: electrostatic discharge current S301 to S305: steps of the flow chart of the method for driving the light-emitting diode according to an embodiment of the present invention