1331241 九、發明說明： 【發明所屬之技術領域】 本發明是有關於一種定電壓及 搞种夕壯$ <電流轉換調控發光二 電SI及方法，且特別是有關於-種利用定電磨及定 調控平面顯示裝置背光模組發光二極體亮度之 【先前技術】 由於光電科技的蓬勃發展，生活令越來越多機會接觸 到各式各樣的通訊或電子產品’例如：個人數位助理 (personal digital assistant ; pDA)、行動電話筆記型電腦、 桌上型顯示器、車用顯示器等[其中，顯示裝置為這些 通訊或電子產品所應共通具備之裝置，因此顯示裝置的優 劣攸關著這些通訊或電子產品的優劣。所以顯示裝置能具 備高畫質、艟積小、重量輕、低驅動電壓、與低消耗功率 專優點是亟於努力之目標。 另外，在顯示器的背光模組中’常用的背光源例如有 冷陰極螢光燈（Cold CathodeFlorescent Lamp ; CCFL)、發光 二極體（Light Emitting Diode ; LED)與電激發光 (Electr〇luminescence; EL)等。由於發光二極體具有體積 小、壽命長、低驅動電壓、耗電量低、耐震性佳等優點， 將逐漸取代冷陰極螢光燈而成為背光源之主流。 第1圖即為習知技術中一種利用定電壓驅動器調控背 光模組之發光二極體串列的方塊圖。定電壓驅動器1〇1提 6 1331241 供發光二極體串列109 —固定電壓，而控制器i〇3則操控 開關105之開啟（0N)及關閉（OFF)的時間比率，來控制發光 二極體串列109的亮暗。亦即，當開關105開啟的時間比 率大於關閉的時間比率，由於人視覺暫留的緣故，亮度相 對地較亮。雖然隨著開關105開啟的時間比率增加，亮度 也因人視覺暫留的緣故相對地增加，但是控制器1〇3只能 調控開關105開啟及關閉的時間比率來決定亮或暗，並不 能調控整個電路的電流大小。 發光二極體串列109為了正常運作需要適當的高壓， 然而過度的高壓將使得發光二極體串列丨〇9損壞，所以在 電路中將發光二極體串列109與限流電阻1〇7串聯，利用 此數十到數千歐姆的限流電阻107來分散電路中發光二極 體串列109所不需要的電壓大小。然而此限流電阻1〇7會 造成無效功率浪費使得效率不佳。 第2圖則為另一種習知技術中利用定電流驅動器調控 者光模組之發光二極體的方塊圖。請參照第2圖，定電流 驅動器201可接受感測電阻207所偵測之回饋訊號以提供 發光二極體串列209 —固定電流。控制器2〇3可控制定電 ml驅動器201所需輸出的電流強度。然而，當電流調至零 時’由於此時感測電阻207無法感測到電流’因此傳遞給 疋電流驅動器201的回饋訊號為零，定電流驅動器2〇1將 無法判斷該如何調整輸出電流，使得整個電路失控。雖然 當電流為零時可以將定電流驅動器2〇1暫時關閉，但是定 電流驅動器201暫時由關閉狀態到全開狀態需要上升時 7 間，對於發光二極體串列209需要快速明亮的調光要求下 便無法即時反應。 、由於疋電壓驅動器調控背光模組之發光二極體之方 ’ &無法㈣電流進而改變發光二極體亮[而且浪費功 率；而定電流驅動器調控背光模組之發光二極體之方法無 ^調整導通的時間’而且電流為科電路會呈現失控狀 二所以為了解決上述問題，另一種習知技術嘗試將定電 • 壓驅動器及定電流驅動器分別合併在同一電路中。 。明參看第3A圖，第3A圖為具定電壓驅動器及定電流 驅動器調控背光模組之發光二極體串列的方塊圖。這樣的 電路配置可以利用定電流驅動器3〇2調整電流大小，定電 . 壓驅動器301避免電流為零時電路失控的問題，而且可以 . 利用第開關304及第二開關305來調控導通時間。其中， 第一開關304控制整個發光二極體串列3〇8總發光時間， 而第二開關305控制總發光時間中的細微時間，如此一來 ，時間調控具有更佳的彈性。雖然定電壓驅動器及定電流驅 動器調控背光模組之發光二極體串列可以調控電流大小及 導通時間，以及解決電流為零時電路失控的問題，但是卻 至少需要有一個定電壓驅動器、一個定電流驅動器、及兩 個開關才能達到上述的功效，所以造成裝置的元件增加， 相對地也使得整個裝置的體積增大而且成本也將因此而提 南0 此外’請參看第3B圖，其為對應第3A圖之電路圖。 雖然可以藉由定電壓驅動器電路312以及定電流驅動器電1331241 IX. Description of the invention: [Technical field to which the invention pertains] The present invention relates to a constant voltage and a method for modulating the illuminating two-electricity and the method, and in particular, And the regulation of the brightness of the light-emitting diode of the backlight module of the flat display device [Prior Art] Due to the vigorous development of optoelectronic technology, life has more and more opportunities to access a variety of communication or electronic products 'eg personal digital assistant (personal digital assistant; pDA), mobile phone notebook computer, desktop display, car display, etc. [The display device is a device commonly used for these communication or electronic products, so the advantages and disadvantages of the display device are The pros and cons of communication or electronic products. Therefore, the display device can have high image quality, small hoarding, light weight, low driving voltage, and low power consumption. In addition, in the backlight module of the display, the commonly used backlights are, for example, a cold cathode fluorescent lamp (CCFL), a light emitting diode (LED), and an electric excitation light (Electr〇luminescence; EL). )Wait. Because the light-emitting diode has the advantages of small size, long life, low driving voltage, low power consumption, and good shock resistance, it will gradually replace the cold cathode fluorescent lamp and become the mainstream of the backlight. Fig. 1 is a block diagram showing a series of light-emitting diodes of a backlight module using a constant voltage driver in a conventional technique. The constant voltage driver 1〇1 raises 6 1331241 for the light emitting diode series 109 to fix the voltage, and the controller i〇3 controls the time ratio of the opening (OFF) and the OFF (OFF) of the switch 105 to control the light emitting diode The light and dark of the body string 109. That is, when the time ratio at which the switch 105 is turned on is greater than the time ratio of the off time, the brightness is relatively bright due to the persistence of the human vision. Although the brightness is also relatively increased due to the persistence of human vision as the time ratio of the switch 105 is increased, the controller 1〇3 can only adjust the ratio of the time when the switch 105 is turned on and off to determine whether the light is bright or dark, and cannot be adjusted. The current size of the entire circuit. The LED array 109 requires a proper high voltage for normal operation. However, excessive high voltage will cause the LEDs 9 to be damaged, so the LEDs 109 and the current limiting resistors are arranged in the circuit. 7 series, using the tens to thousands of ohms of the current limiting resistor 107 to disperse the voltage level that is not required for the LED array 109 in the circuit. However, this current limiting resistor 1〇7 causes waste of wasted power and makes it inefficient. Figure 2 is a block diagram of another conventional technique using a light-emitting diode of a constant current driver modulator optical module. Referring to FIG. 2, the constant current driver 201 can receive the feedback signal detected by the sensing resistor 207 to provide the LED 209-fixed current. The controller 2〇3 can control the current intensity required to output the power of the ml driver 201. However, when the current is adjusted to zero 'because the sense resistor 207 cannot sense the current at this time', the feedback signal transmitted to the 疋 current driver 201 is zero, and the constant current driver 2 〇 1 cannot determine how to adjust the output current. Make the entire circuit out of control. Although the constant current driver 2〇1 can be temporarily turned off when the current is zero, the constant current driver 201 temporarily needs to rise from the off state to the fully open state, and a bright and bright dimming requirement is required for the LED series 209. There is no immediate response. Because the 疋 voltage driver regulates the side of the light-emitting diode of the backlight module, the current cannot change the light-emitting diode [and wastes power; and the method of regulating the light-emitting diode of the backlight module by the constant current driver is not ^ Adjusting the conduction time' and the current is out of control for the circuit. Therefore, in order to solve the above problem, another conventional technique attempts to combine the constant voltage and voltage driver and the constant current driver in the same circuit. . Referring to FIG. 3A, FIG. 3A is a block diagram of a LED array of a backlight module with a constant voltage driver and a constant current driver. Such a circuit configuration can adjust the current magnitude by the constant current driver 3〇2, and the power is applied. The voltage driver 301 avoids the problem that the circuit is out of control when the current is zero, and the switch 304 and the second switch 305 can be used to regulate the on-time. The first switch 304 controls the total illuminating time of the entire illuminating diode series 3〇8, and the second switch 305 controls the subtle time in the total illuminating time, so that the time adjustment has better elasticity. Although the fixed voltage driver and the constant current driver regulate the LED array of the backlight module, the current magnitude and the on-time can be regulated, and the problem that the circuit is out of control when the current is zero is solved, but at least one constant voltage driver and one fixed voltage are required. The current driver and the two switches can achieve the above-mentioned effects, so that the components of the device increase, and the volume of the entire device is relatively increased, and the cost will also be increased. In addition, please refer to FIG. 3B, which corresponds to Circuit diagram of Figure 3A. Although it can be powered by the constant voltage driver circuit 312 and the constant current driver
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