200904256 九、發明說明： 【發明所屬之技術領域】 本發明係有關一種發光二極體(Light Emitting Diode，LED)之回饋 (feedback)控制系統及控制方法’特別是關於一種依溫度變化回饋控^ 流經發光二極體之電流量的控制系統及控制方法。 【先前技術】 #統之液晶顯示m模組大部份均採賴術已成熟之冷陰極管 (Cold Cathode Fluorescent Lamp ’ CCFL)作為光源，然而冷陰極管本 ( 身存在著演色性不佳、需高壓驅動、含汞、發光頻譜含紫外線(UV)波 段、啟動速度慢、燈管易碎裂及色度控制不佳等問題，因此，擁有高 演色性、低驅動電壓、無汞、不放射Uv A、點燈啟動快速、固態= 裝不易碎裂、可動態雛色度衫項優點之發光二極體已成為新 光源的最佳選擇。 為了達到高色彩飽和度之需求，發光二極體應用於背絲組時， 係使用紅色(Red)、藍色(Blue)、綠色(〇「_三色之發光二極體混合成 所需之白光’其中紅綠藍阳印三色間光強度的比例決定了混光後的 色度’即背光模組之色溫’所以背光模組欲呈現良好的色度則必須維 I持紅雜三色之光強度在-固定的比例。當發^二極體啟動而溫度升 局時，由於現行之各色發光二極體所使用的材料與組成均不相同，對 於溫度的敏感度也，隨著溫度升高，其光職衰減的程度係 如第-騎示，其巾紅絲聽度最A，綠光奴喊光最小，此衰 減現象不僅造成整體輝度下降，更影_先設定之RGB光強度比例， 造成顯示端色度的飄移。 —現行之解决方法係如第二圖所示，使用一組色彩感測器1㈣測顯 示端背光模組U中RGB三色發光二極體12光強度的變化，並依據 $光強度變化趨勢回饋控制RGB光強度比例，補償衰減色光強度，使 月光拉組14維持一定之_度。然而色彩感測器1〇的價格昂貴，在 200904256 成本下降快速的液晶顯示器產業令為― 色彩感測器1〇必須設置於背光模;14中混光 表整體光學表現之位置，此最佳位置非常難以拿捏.若mm =;：^=^!=:須_ 組色 =12異常㈣極“成ΐ;感 現嚴重失常。另-方面，心㈣心… I減|體光學表 區域、、，且14裡除了光源以外之絕大部分 ，嫩射 =先-極體回饋控财法及系統，使其不具有上述色彩感測器之缺 【發明内容】 统，：a：# ^ j目的係、在提供—種發^二極體之回饋控制方法及系 ί其係以溫度感測器代替色彩感測器感測系統中溫度的變化，再依 度ϊγ算出發光二極體之光強度衰減量，因溫度感測器 之偏格便且，可有效降低生產成本。 -产==之ί—目⑽在提供—種液晶顯示器背❹、統，其係使用 光二極體因溫度升高所引起之光強度衰減，維 、極體間光強度之_ ’使f光线維持穩定之色輝度。 夹規之再—目的係在提供—種不影響液晶_器背光系統光學 表見之n極體_控制方法m由於 ==對光學之影響，因此背光系統中發光二極 轉內成鱗使其誤判，1溫度_料需設置於背光 糸、'先内掀射面區域，不會影響其光學表現。 =本,，在發光二極體之關躲置有1测溫度變化之溫 又H並以—控制器依偵測之溫度變化計算出發光二極體的光強 200904256 度衰減量，再調整流經發光二極體之電流以調整其光強度。 發明實施例配合所附的圖式詳加說明’當“易瞭解本 I月之目的技術内容、特點及其所達成之功效。 【實施方式】 写發光二極體回饋控制系統係以溫度感測器取代色彩感測 ㈣之溫繼，由於各色篆極體之光衰程 度與，皿度之_為—已知_，可以—控㈣依細之溫度變化 ΐ各色發光二極體光強度之衰減量，並調整流經該發光二極體之電流 i以调正其;^自度。其中發光二極體光強度之衰減量與溫度變化係具 有一比例關係，只要根據溫度感測器所感測之溫度，即可得出光衰量二 或是於控制ϋ巾喊-關絲，以絲方式求得衰減4。由於發光二 極體之光強度與㈣經其上之H量係近似—線性關係，控制器可套用 =性義式或峽-關係表以絲方式細，即可得知應調整之電 々IL里大j、電抓里之調整可分為提昇或降低流經發光二極體之電流 量，其t提昇電流量可補償發光二極體因溫度上升所造成之光強度衰^ 減，降低電流量則是以犧牲少許亮度之作法使整體之色度穩定，而除 了以一受控制器控制之電源供應器完成電流量調整之功能外，更可以 一同樣受控制器控制之脈波產生器提昇或降低發光二極體開關訊號的 責任週期係數(duty factor)，調整流經發光二極體之電流量以調整其光 強度。 以一液晶顯示器背光模組為例，第三圖為本發明使用於液晶顯示 器背光模組之系統方塊示意圖，其中紅綠藍三色之發光二極體22係用 以提供所需之白光’三色間光強度的比例決定了混光後的色度，而三 色光強度之總和即為混光後之亮度。在一實施例中，為了達成背光模 組24所需之白光色度’紅色發光二極體之輸入電流係45〜48毫安培 (mA)，綠色發光二極體之輸入電流係50〜53mA，藍色發光二極體之輸 入電流為40〜43mA，當發光二極體22達到穩定狀態時，溫度感測器 7 200904256 20偵測到接面溫度(junctj0n temperature)上升至8(rc，根據第一圖之 光衰量與溫度之比例關係圖可知，紅綠藍三色發光二極體的亮度衰減 幅度各不相同’導致三色光賴的_偏離縣之設定值，使白光色 度產生偏移，紅光明顯不足，綠光次之，藍光衰減最少，同時混合光 之亮度也會降低。 -第四圖為本發明之回饋控㈣統—實施例之方塊示意圖，如圖中 所不’為了調整背光模組之白光色度，控湘26在接收溫度感測器 20所感測之接面溫度後’根據式⑴之關係式或光強度衰減量與溫度變 { 化之比麵絲計料各色發光二極體22的亮度下降比例，其中當接 面/皿度上升至8GC時，紅光之亮度下降比例約為_5G%，綠光之亮度下 降比例約為-20%，藍光之亮度下降比例約為-3%，由於發光二極體22 與輸入電流約為-線性變化之關係，控制器26藉由控制電源供應器 28將二工綠盖二色發光二極體22的輸入電流各提昇50%、2〇%及3%， t補其冗度損失。另外也可如第五圖所示以脈波產生器30調整各色 ^光二極體22關婦乂責任聊舰，將紅色發光二極體之電流量 提昇至67〜70mA，綠色發光二極體之電流量提昇至60〜63mA，藍色 ^光-極體之電流量提昇·至41〜44mA，使三色光之比例符合原先之預 (=。而除了提昇輸人電流使發光二極體22間光強度比例穩定、亮度 θ南之外’也可降低部分發光二極體22之輸入電流，以維持RGB的 比例，保持所需之白光色度。 上述之實補餘發光二歸達_錄驗輯瞒控制，然 士發月並非限疋於穩定狀態才能實施，在啟動到穩定的過程中，每 ΙΙΠ點均可隨時進行發光二極體之回饋控制。而溫度感測器不-定 之光模_發光三鋪之間’只要在式⑴巾增加距離等變數 士、工、’同樣可財得發光二極體之絲量並進行後_制之步驟。 f發明相較於習知技術’因溫度感測器之價格便宜，可有效降低 成本。且背光模組中大量使用金屬材料，如紹背板、銘基板電路 200904256 可代表整 及散熱器等，都是熱的良導體，因此在模組中可輕 體模組溫度變化趨勢之位置。再者發光二極體里 編統中發光二極體的異常;== 感測使其誤判，且溫度感·不需設 = 射面區域，不會影響其光學表現。 彳K統内部反 以上所述_由實施舰日林㈣之_ 離本發明所揭示之精神啦成之等效修#或修改，仍 應包3在以下所述之申請專利範圍中。 【圖式簡單說明】 第i為f知之發光二極體絲量與溫度之比例關係圖。 第一圖為習知之色彩感測器回饋控制系統。 ，三圖為本發明使用於液晶顯示器背光模組之系統方塊示意圖。 =四圖為本t明卿電源供應器之回输锻統—實施例之方塊示意 =五圖為本發明彻脈波產生器之_控制n實施例之方塊示意 圖。 【主要元件符號說明】 10色彩感測器 12發光二極體 14背光模組 20溫度感測器 22發光二極體 24背光模組 26控制器 28電源供應器 30脈波產生器200904256 IX. Description of the Invention: [Technical Field] The present invention relates to a feedback control system and a control method for a Light Emitting Diode (LED), particularly regarding a temperature-dependent feedback control A control system and a control method for the amount of current flowing through the light-emitting diode. [Prior Art] Most of the liquid crystal display m modules of the system are used as the light source of the Cold Cathode Fluorescent Lamp 'CCFL, but the cold cathode tube (the color rendering is poor, High-speed drive, mercury-containing, ultraviolet spectrum (UV) band, slow start-up speed, fragile lamp and poor chroma control. Therefore, it has high color rendering, low driving voltage, no mercury, no radiation. Uv A, fast lighting, solid state = light-emitting diodes with the advantage of being easy to break and dynamic color-changing shirts have become the best choice for new light sources. In order to meet the demand for high color saturation, LEDs When applied to the back wire group, red (Red), blue (Blue), and green (""three-color light-emitting diodes are mixed into the desired white light", among which the light intensity between the red, green, and blue colors is used. The ratio determines the chromaticity after the light mixing, that is, the color temperature of the backlight module. Therefore, if the backlight module wants to exhibit good chromaticity, it must maintain the light intensity of the red and three colors in a fixed ratio. When the polar body starts and the temperature rises, due to the current colors The materials and compositions used in the light-emitting diodes are different. The sensitivity to temperature is also the same as the temperature-increasing degree, such as the first-riding, and the redness of the towel is the most A, green. The light slave shouts the smallest light. This attenuation phenomenon not only causes the overall luminance to drop, but also the ratio of the RGB light intensity set first, which causes the chromaticity of the display end to drift. - The current solution is as shown in the second figure. The color sensor 1 (4) measures the change of the light intensity of the RGB three-color light-emitting diode 12 in the backlight module U of the display terminal, and controls the RGB light intensity ratio according to the change trend of the light intensity to compensate the attenuation light intensity, so that the moonlight pull group 14 Maintaining a certain degree. However, the price of the color sensor is expensive, and the cost of the liquid crystal display industry is reduced at the time of the 200,904,256. The color sensor 1 must be set in the backlight mode; the overall optical performance of the light mixing meter in 14 Position, this best position is very difficult to pinch. If mm =;:^=^!=: _ group color = 12 abnormal (four) pole "crowd; sense of serious disorder. Another - aspect, heart (four) heart... I minus | Body optics table area, and 14 in addition to the light source Most of the outside, the ejaculation = first-polar body feedback control method and system, so that it does not have the above-mentioned color sensor deficiency [invention content] system, a: # ^ j destination system, in the provision of The feedback control method and the system of the diode are replaced by a temperature sensor instead of the temperature sensor in the color sensor sensing system, and then the light intensity attenuation of the light-emitting diode is calculated according to the degree ϊγ, because of the temperature sense The bias of the detector can effectively reduce the production cost. - Production == ί - (10) provides a kind of liquid crystal display back-up, which uses the light intensity decay caused by the temperature rise of the photodiode , the light intensity between the dimension and the polar body _ 'Let the f light maintain a stable color luminance. The re-adhesive of the clamp is intended to provide a kind of n-pole body that does not affect the liquid crystal _ backlight system _ control method m due to = = The influence on the optical, so the backlight in the backlight system is scaled to make it misjudged, 1 temperature _ material needs to be set in the backlight 糸, 'first inward 掀 surface area, will not affect its optical performance. = Ben, in the light-emitting diode off, there is a temperature change of H measured and H is calculated by the controller according to the temperature change detected by the controller, the light intensity of the light-emitting diode is 200,904,256 degrees, and then the flow is adjusted. The current of the LED is adjusted to adjust its light intensity. The embodiments of the present invention are described in detail with the accompanying drawings, and the technical contents, characteristics, and effects achieved by the present invention are easily described. [Embodiment] The light-emitting diode feedback control system is temperature-sensing. Instead of color sensing (4), the temperature is slowed down due to the degree of light decay of the various color bungee bodies, and the value of the dish is known as - can be controlled - (4) according to the temperature change of the light, the light intensity of the light-emitting diodes Decrease and adjust the current i flowing through the light-emitting diode to adjust its self-degree. The attenuation of the light intensity of the light-emitting diode has a proportional relationship with the temperature change, as long as it is sensed according to the temperature sensor. The temperature can be obtained by the amount of light decay or by controlling the squeaking-swinging wire and determining the attenuation by the wire method. 4. Because the light intensity of the light-emitting diode is similar to the amount of H above it. The controller can apply the = sex or the gorge-relational table in the form of silk. It can be known that the adjustment of the electric 々 IL in the large j, the adjustment of the electric grasp can be divided into raising or lowering through the light-emitting diode The electric current, the amount of current boosted by t can compensate the temperature of the light-emitting diode The light intensity caused by the rise is reduced, and the current is reduced by sacrificing a small brightness to stabilize the overall chromaticity. In addition to the function of adjusting the current amount by a controller-controlled power supply, A pulse wave generator controlled by the controller also raises or lowers the duty factor of the LED switching signal, and adjusts the amount of current flowing through the LED to adjust its light intensity. The module is taken as an example. The third figure is a block diagram of the system used in the backlight module of the liquid crystal display. The red, green and blue light-emitting diodes 22 are used to provide the required white light's light intensity between the three colors. The ratio determines the chromaticity after the light mixing, and the sum of the three color light intensities is the brightness after the light mixing. In an embodiment, in order to achieve the white light chromaticity required for the backlight module 24, the input of the red light emitting diode The current system is 45 to 48 milliamperes (mA), the input current of the green light emitting diode is 50 to 53 mA, and the input current of the blue light emitting diode is 40 to 43 mA, when the light emitting diode 22 reaches a steady state. The temperature sensor 7 200904256 20 detects that the junction temperature (junctj0n temperature) rises to 8 (rc, according to the ratio of the light decay amount to the temperature of the first figure, the brightness of the red, green and blue three-color light-emitting diodes is known. The attenuation amplitudes are different', which causes the three-color ray to deviate from the set value of the county, causing the white light chromaticity to shift, the red light is obviously insufficient, the green light is second, the blue light attenuation is the least, and the brightness of the mixed light is also reduced. The fourth figure is a block diagram of the feedback control (four) system of the present invention. In the figure, in order to adjust the white light chromaticity of the backlight module, the junction temperature sensed by the control temperature sensor 20 is controlled by the control 26 After the relationship according to the formula (1) or the light intensity attenuation amount and the temperature change, the ratio of the brightness of the light-emitting diodes of the respective color light-emitting diodes 22 is decreased, wherein when the junction/dishness rises to 8GC, the red light The brightness reduction ratio is about _5G%, the brightness reduction ratio of green light is about -20%, and the brightness decrease ratio of blue light is about -3%, because the relationship between the light-emitting diode 22 and the input current is about - linear change, control The device 26 will control the power supply 28 Engineering green top dichroic light-emitting diodes in each input current 22 up to 50%, 2〇% and 3%, t make up for loss of redundancy. In addition, as shown in the fifth figure, the pulse wave generator 30 can be used to adjust the color of the light-emitting diode 22 to support the woman, and the current of the red light-emitting diode is raised to 67-70 mA, and the green light-emitting diode is The current is increased to 60~63mA, and the current of the blue-light-polar body is increased to 41~44mA, so that the ratio of the three-color light is in line with the original pre- (=. In addition to increasing the input current, the light-emitting diode 22 is The light intensity ratio is stable, and the brightness θ is outside the south. It can also reduce the input current of the partial light-emitting diode 22 to maintain the ratio of RGB and maintain the desired white light chromaticity. The above-mentioned real complementary light illumination The collection control is not limited to the steady state. In the process of starting to stability, the feedback control of the LED can be performed at any time. The temperature sensor does not determine the optical mode. _ Between the three tiles of the illuminating 'as long as the distance of the formula (1) increases the distance, such as the number of workers, the work, 'can also obtain the amount of the filament of the light-emitting diode and carry out the post-process. f invention compared to the conventional technology 'cause Temperature sensors are cheaper and can effectively reduce costs. A large number of metal materials are used in the optical module, such as the back plate, the substrate circuit 200904256 can represent the whole and the heat sink, etc., and are all good conductors of heat, so the position of the temperature change trend of the light body module can be in the module. The abnormality of the light-emitting diode in the illuminating diode; == Sensing makes it misjudged, and the temperature sense does not need to be set = the surface area, which will not affect its optical performance. 彳K system internal anti-above _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ f knows the relationship between the amount of filament and temperature of the light-emitting diode. The first figure is the conventional color sensor feedback control system. The three figures are the block diagram of the system used in the backlight module of the liquid crystal display. The block diagram of the embodiment of the present invention is shown in the block diagram of the embodiment of the present invention. 12 LED diode 14 backlight module 20 temperature sensor 22 light-emitting diode 24 backlight module 26 controller 28 power supply 30 pulse generator