201105167 六、發明說明： 【發明所屬之fe術領域】 本發明係關於一種以一定週期之脈衝信號驅動發光 二極體等發光元件之光源驅動方法及光源驅動裝置。 【先前技術】 近年來，使用發光二極體（LED)之光源正漸漸廣受利 用。例如，採用於液晶顯示裝置等之背光源（back light) ' 汽車車内燈或前照燈、室内外之照明裝置等。進行此種LED 之光1調整之最簡單之方法，係為調整流通於LED之電流 ，。然而，LED之光色特性，因為波長會依據流通之電流 量變化，而產生可看到可視色變化之問題。為了改善此種 問題，在光ΐ调整控制方面，一般係使用脈衝寬度調變 (Pulse Width Modulation，PWM)方式（專利文獻 i、2)。201105167 VI. Description of the Invention: The present invention relates to a light source driving method and a light source driving device for driving a light-emitting element such as a light-emitting diode with a pulse signal of a certain period. [Prior Art] In recent years, light sources using light-emitting diodes (LEDs) are becoming increasingly popular. For example, it is used in backlights such as liquid crystal display devices, such as automobile interior lamps or headlights, indoor and outdoor lighting devices, and the like. The easiest way to adjust the light 1 of such an LED is to adjust the current flowing through the LED. However, the color characteristics of the LED, because the wavelength varies depending on the amount of current flowing, creates a problem that the visible color change can be seen. In order to improve such problems, Pulse Width Modulation (PWM) is generally used for the adjustment control of apertures (Patent Documents i and 2).
、此外，在專利文獻3中，係揭示一種以檢測連接有LED 光源負載邰中之峰值（peak)電流而防止低電壓時之過電 流為目的之裝置。 第8圖係為顯示使用習.知謂方式之LED點亮電路之 二⑽點亮電路係為具備有電流限制電阻 ^電H導體開關Q 〇、P 控制電路之構成。前述電流限 係為限制流通於⑽之電流之電阻器，且對 而另一方/接。此串聯電路之一方係與電源線Vcc連接， 制電路S係經由半導體開關Q〇與接地（GND)連接。PWM控 體開關系為具備將以PWM方式調變之脈衝信號供給至半導 Q0之閘極，使半導體開關Q0導通（on)/關斷（off) 4 321383 201105167 之功能者。 此外，所連接之發光元件之驅動時序（timing)及供給 之電流值等驅動條件，係有預先以表單（tab 1 e)的形式存放 - 於控制部内，且根據此表單而設定之情形。 - [先行技術文獻] [專利文獻] [專利文獻1]日本特開2006-210835號公報 [專利文獻2]日本特開2007-4995號公報 [專利文獻3]日本特開2004-227951號公報 【發明内容】 [發明所欲解決之課題] 然而’以上述第8圖所示之點燈電路使LED長時間點 燈時’ LED本身會因為LED所消耗之電力而發熱。隨著此 發熱會產生溫度上升，而產生額定電壓值VF降低之現象。 當則述點燈電路處在此種情況時’由於電源受到定電壓控 制’因此會有電流限制電阻器R0之兩端電壓及電路電流會 隨者VF之降低而上升，導致led之發光亮度變動之問題。 此外’半導體開關Q〇的⑽電阻亦會因為半導體開關Q〇 之發熱而變化，結果產生與LED之溫度上升同樣之問題。 再者，供給電壓產生變動時，亦會有直接轉變為電流值之 變動，而成為LED之發光亮度變動之主要原因之情形。尤 其是屬於半導體之LED之VF，由於會因為批次（lot)之製 造差異等而使差異變大，因此在連接複數個[肋於負载側 時，並不容易在維持一定發光亮度之狀態下使之連續發光。 321383 5 201105167 此外，一般雖係以一定週期之導通/關斷所形成之脈 衝來驅動發光元件，然而並未進行在前述一定週期之導通 /關斷之導通期間之脈衝中更細部地予以脈衝驅動’更進 而將此脈衝驅動一面維持接近發光元件之驅動能力之極限 值之峰值電流值之附近一面予以控制。 因此，本發明之目的係提供一種光源驅動方法及光源 驅動裝置’可算出所連接之發光元件之峰值電流值，且根 據此峰值電流值來規定前述發光元件之導通期間，並且使 在此導通期間中脈衝之最大振幅成為前述峰值電流值，而 且將導通期間及關斷期間之工作週期比（d u t y r a t丨〇 )設為 可變，藉此而可抑制消耗電力，同時獲得高亮度且穩定之 發光。 [解決問題之方案] 為了解決上述問題，本發明之光源驅動方法係包括下 述步驟：一面控制電流一面將電流供給至連接發光元件之 光源負載側並檢測額定電壓值；從該額定電壓值算出前述 發光元件固有之絕對最大額定電流值，並在不超越該絕對 最大額定電流值之範圍内算出可流通於該發光元件之峰值 電流值；為了根據該峰值電流值來規定前述發光元件之導 通期間，而產生藉由導通期間與關斷期間之工作週期比設 為可變之第1導通/關斷週期所形成之第丨驅動脈衝；藉 由在該第1驅動脈衝之導通期間中進一步進行開關 (switching)，產生由脈衝之最大振幅成為前述峰值電流 值，而且將導通期間及關斷期間之工作週期比設為可鐵之 6 321383 201105167 、第2導通/_週期所形狀第2驅動脈衝；及藉由將該 =2驅動脈衝所驅動之電流施加於前述光源負載侧，使發 光元件連縯發光驅動。 .此外:本發明之光源驅動裝置係包括：光源負載部， 立接發光兀件’負載容量檢測部，藉由供給至該光源負載 =電流而檢測前述發光元件之額定電壓值 ;信號處理控 :「、根j由該負載容量檢測部所檢測出之額定電壓值算 · = ㈣光疋件穩態驅動之額定電流值及從此額定 ^值算出前述發光元件时之絕對最大駭電流值，且 =超過該㈣最大額定電流值之範圍㈣行算出及設定 二上於該發光元件之蜂值電流值；及定電流脈衝驅動 :招艮據前述峰值電流值進行脈衝寬度調變，藉以產生藉 .开^定前述發光元件之導通期間之第i導通/關斷週期所 方形之第1驅動脈衝’並且藉由在該第1驅動脈衝 之工 驅 巾5成^間中進—步進行開關，產生藉由使脈衝之最大振 =為前述峰值電流值’而且將導通期間及關斷期間之 動=比設為可變之第2導通/關斷週期所形成之第2顯 ’將前述第2驅動脈衝所驅動之電流施加於前述光 發光^細使與前述_載料接之發光元件連續 (發明之功效） 發光^本發明之光源驅動方法’藉由在最初檢測連接有 算出中之光源負載側之額定電壓值，且從該額定電壓值 迷發先兀件固有之絕對最大額定電流值，即可將在 321383 7 201105167 穩定狀態下以最大限度導出前述發光元件之發光特性 值電流值予以設定。再者，以該峰值電流值為依據，藉由 從規定發光元件之導通_之第1 .__進行前述^通 期間中之_，產生使脈衝之最大振幅成為前述峰值電、士 值’而且將導通期間及關斷期間之工作週期比設為可變: 第2驅動脈衝’並將由該第2驅動脈衝所驅動之電流施加 於前述光源負·，藉錢前述發光元件穩定地連續發光 驅動，並且可謀求整體消耗電力之降低。 x 此外’依據本發明之光源驅動裳置，具有甩以預先檢 測與光源負載側連接之發光元件之負載容量的手段，並且 可以在信號處理㈣部巾產生麟前述發光元件之驅^t 力從前述負载容量算出之峰值電流值直接驅動發光元件= 驅動脈衝。藉此，即可在維持發統件之驅動能力於一定 水準之狀態下’減低發熱量及消耗電力。 【實施方式】 以下根據所附圖式詳細說明本發明之光源驅動方法 及光源驅動裝置之實施祕。第丨圖係為本發明之光源驅 動方法之概略流㈣，第2圖係為顯示本發明之光源驅動 裝置10之整體構成。如第1圖所示’本發明之光源驅動方 法，係在電源導通（0N)時，檢測與光源負載部12連接之單 一或複數個發光元件（LED)17之額定電壓值VF(步驟_1；^ 在此檢測之際，係使光源負載部12從微小值階段性提高債 測電流，一面測量施加於光源負載部12之一對電極端子、 16間之電壓一面進行。前述偵測電流係在前述電極端子“ 321383 8 201105167 間之電壓成為穩定在一定位準之狀態時讀取電壓值，且從 該讀取結果求出額定電壓值VF。 接著，在信號處理控制部15内之CPU18，從在步驟-1 中所檢測出之額定電壓值VF算出使LED17在穩態發光驅動 所需之額定電流值IF。此外，從該額定電流值（IF)算出在 不破壞LED17之範圍下可流通之絕對最大額定電流值 (IPmax)(步驟-2)。此等額定電流值（IF)及絕對最大額定電 流值（IPmax)係根據CPU18之記憶體内預先儲存之計算式 而算出，且從該算出結果而設定實際以高效率驅動LED17 所需之峰值電流值I'PCIFS IPClPmax)(步驟-3)。 接下來，根據在步驟-3所設定之峰值電流值IP而產 生用以使LED17脈衝驅動之方形之發光週期信號（第1驅動 脈衝）P1 (步驟-4、第3圖）。此第1驅動脈衝P1係由藉由 前述CPU18進行脈衝寬度調變之連續之第1導通/關斷週 期T1所構成，係連續重複電流流通之期間（導通期間）與電 流不流通之期間（關斷期間）。舉例而言，第1導通/關斷 週期T1係設定為約200Hz、工作週期比為相對於導通期間 為1，關斷期間為9。前述T1係依據LED17之驅動能力而 適當設定。 前述第1驅動脈衝P1係藉由在第1導通期間之中高 速開關（switching)，而產生使流通電流之期間更細部斷續 之第.2導通/關斷週期T2所構成之方形之發光驅動信號 (第2驅動脈衝）P2(步驟-5)。第2導通/關斷週期T2在前 述之T1之條件下，舉例而言，係設定為約300kHz、工作 9 321383 201105167 週期比與第1驅動脈衝P1同樣，相對於導通期間為1，關 斷期間為9。第2驅動脈衝P2係與前述第1驅動脈衝P1 同樣以依據LED17之種類及數量等之驅動能力所設定之峰 值電流值IP為依據，設定脈衝之最大振幅及工作週期比。 將由該第2驅動脈衝P2所驅動之電流施加於光源負載側， 藉此而使LED 17發光驅動（步驟- 6)。此外，如第4圖所示， 前述第2驅動脈衝P2係經由RC積分電路27，藉此成為在 第2導通/關斷週期T2重複充放電之三角波狀之發光驅動 波形W2。再者，從藉由此發光驅動波形W2所形成之脈衝， 輸出藉由在第1導通/關斷週期T1重複充放電之三角波狀 之發光週期波形W1所產生之電流。如此，將藉由以峰值電 流值IP為最大振幅寬度之發光週期波形W1所產生之電流 施加於與光源負載側12連接之LED17，即可抑制消耗電 力，同時以高效率使LED17連續在穩定之狀態下發光驅動。 第2圖係顯示用以實現上述光源驅動方法之光源驅動 裝置之構成例。此光源驅動裝置10係在電力供給源11與 光源負載部12之間，具備定電流脈衝驅動部13、負載容 量檢測部14、及信號處理控制部15而構成。電力供給源 11係具有AC全球通用（worldwide)輸入、DC輸入、電池輸 入之任一者，而成為定電流脈衝驅動部13之定電壓源。光 源負載部12係具備一對電極端子16，而在此電極端子16 間係連接有單個或複數個LED17。信號處理控制部15係具 備CPU18，而在此CPU18内係儲存有從施加於前述電極端 子16間之電壓值算出LED17之額定電壓值（VF)、額定電流 10 321383 201105167 值（IF)、絕對最大額定電流值（IPmax)及最適於驅動之峰值 電流值（IP)之計算式。 在前述信號處理控制部15内係設有偵測電流設定部 -29 ’其係從電力供給源11 一面控制一面供給用以預先偵測 •光•源負載部12之負載容量（w)之偵測電流。此偵測電流設 定部29係為了使從電力供給源11所供給之電流從微小值 階段性地變化’而例如具備預先設定有與最小從起最 .大至1〇mA為止對應之LED之功率（w)及根據此功率之額定 電壓值之轉換表單。在啟動光源驅動裝置丨〇之際，按照前 达轉換表單從較低之電流值一面依序逐步提高一面供給至 光源負載部12，且逐次偵測LED17發光之際之電壓值，且 項取此電壓值穩定之時而偵測前述LED17之標準之功率 (w)以此所偵測之功率值為依據而設定使⑽17連續發光 所需之額定電屋值（VF)。 以則述額定電壓值VF為基準之峰值電流值IP，係藉 =將^對最均定電流值（IPmax)乘上預定之係數!^而獲 述係數k係用以規定發光量者，例如若設定為0.9， 可獲知j IPmax附近之高亮度發光。此係數k只要在不超 過1之範®(〇<k<1)下均可任意設L由此設定即可 -周正LED之發光量。另外，此係數k之設定，係可藉由與 光，驅動裝置10之外部端子（C0NT)連接之可變電阻器、微 調裔（trimmer)或指撥開關（DIp switch)等之調整器件 (device)從外部設定。 以》又疋峰值電流值I p之手段而言，亦可先使 321383 11 201105167 額定電流值參照表單（VF— IF表單）及絕對最大額定電流 值參照表單（IF— IPmax表單）記憶於CPU18之記憶體内， 且藉由以此等參照表單為依據之程式處理來算出。在前述 VF_ IF表單中係設定以在與前述光源負載部12連接之 LED17所檢測之功率值為基準之額定電壓值VF、額定電流 值IF ’而在if — ipmax表單中，係設定與前述額定電流值 IF對應之絕對最大額定電流值Ipmax。 在此，所謂額定電壓值VF係指可使與前述光源負載 邛12連接之LED 17在穩足之狀態下發光為一定明亮度之電 壓值，而額定電流值IF係為該時流通於LED17之值。此外， 所明絕對最大額定電流值ipmax係為在一定條件下可保證 LED17之動作之最大容許值，若超越此值則會導致元件之 破壞，因此乃規定為即使短時間亦不超越之值。相對於此， 本發明中之峰值電流值IP，係指前述額定電流值IF以上 且不超過絕對最大額定電流值IPmax之範圍（IFS IP< IPmax) ’以維持此範圍之方式進行脈衝軀動控制。另外， 剛迷額定電壓值VF及額定電流值IF係依據構成前述 LED17之個數及連接形態或要設定之明亮度而變動。 本發明之光源驅動裝置1〇係以藉由信號處理控制部 is及定電流脈衝驅動部13，在滿足IF$ Ip<IPmax之關 係之範圍内控制前述峰值電流值IP，且使此峰值電流值jp 以預定之工作週期比進行開關之方式構成。 — 如第2圖所示，前述定電流脈衝驅動部13係具備： 疋電流控制部21、第1開關元件qi 、電流檢測元件R1、 12 321383 201105167 ' 及第2開關元件Q2。定電流控制部21係以恆常監視流通 於光源負載部1.2之電流值II並一直固定供給之方式控 制。在前述定電流控制部21中係具備升降壓轉換器 - (converter)(未圖示），從電力供給源11增減電流位準， . 以填補流通於與光源負載部12連接之LED17之電流值II 之增減份。藉此，而維持一定之電流位準。第1開關元件 Q1係用以產生由第1導通/關斷週期T1所構成之第1驅 動脈衝P1者，經由第1驅動電路23以預定之時序使由前 述升降壓轉換器所增減之電流信號進行開關，藉此而設定 導通期間與關斷期間之比率（工作週期比）。前述第1導通 /關斷週期T1係控制為200Hz左右。此外，工作週期比雖 係控制為使前述LED17具有額定亮度，惟藉由將導通期間 設定為50%左右或其以下，即可減低發熱量及消耗電力。 在本實施形態中，亦以導通期間為10%、關斷期間為90% 之方式設定工作週期比。 前述電流檢測元件R1係串聯連接於前述光源負載部 12之輸入側，用以偵測流通於此電流檢測元件R1之電流 值，並反饋（feedback)至前述定電流控制部21。第2開關 元件Q2係用以產生由第2導通/關斷週期T2所構成之第 2驅動脈衝P2者，可在前述第1開關元件Q1導通之期間 動作。此第2開關元件Q2係根據經由第2驅動電路24之 來自信號處理控制部15之開關控制信號SW而高速開關。 藉此開關，第2導通/關斷週期T2係控制為300kHz、工 作週期比在導通期間為10%、關斷期間為90%。 13 321383 201105167 前述定電流脈衝驅動部13係在與前述光源負 之電極端子16連接之輸出側設有由電感器（線圈）li斑 容器C卜C2所組成之充放電電路3Q。在此充放電電路^ 中’係每當第1開關元件Q1及第2開關元件Q2導通，、力0 通於LED17之電流亦充電於電容器c2。再者，在第】’流 元件Q1及第2開關元件Q2關斷期間，充電於電容器開關 之電荷係放電，而使電流流通於LED17。藉此，不僅在= 開關元件Q1及第2開關元件Q2之開關之各個導通期1 即使在關斷期間亦可對LED17持續供給一定量之電流。a ’ 此，儘管驅動電流儀為間歇性之方形波狀之闕，仍在因 LED17連繽流通一定之電流，因此可維持發光亮度於一 定，並且可減低消耗電力。另外，線圈L1與電容器ο饮 為了使因為第2開關元件Q2導通而流通於LED17之峰值 流值IP平滑化所設。 $ 如第2圖所示，負載容量檢測部14係具備：電沆檢 測元件R2、RC積分電路27、及差動放大器烈。電^檢 元件R2係使用高精確度之分流電阻器（shun^ 、 resistance)，而檢測藉由前述第2開關元件收之開關而 流通於LED17之電流。在RC積分電路27中，係藉由第 開關元件Q 2之導通/關斷週期將由前述電流檢測元件』 所檢測出之檢測電流進行積分。差動放大器28係取前述 RC積分電路2 7所積分之信號與基準電壓源3 2之差八、 放大，將放大後之檢測電壓VI予以輸出。此檢測電 係送至信號處理控制部15。 321383 14 201105167 第5圖係為在前述充放電電路30内設置保護電路31 時之構成例。此保護電路31係由用以限制對電容器C2之 充電電流之限制電阻器R4、及用以使放電電流旁通 - (bypass)之整流元件（二極體）D1所構成，而可防止光源負 - 載部12之電極端子16在開路之狀態及光源驅動裝置10 之主電源在導通之狀態下進行LED17之連接之際流通過電 流。依據此保護電路31，在藉由第2開關元件Q2之開關 所產生之第2驅動脈衝P2之導通期間中，與由電容器C1 及線圈L1進行之峰值電流值IP之平滑化同時開始對電容 器C2之充電，而使LED17點燈。此時，限制電阻器R4係 具有防止突入於電容器C2之電流與限制充電電流之作 用。再者，在轉移至前述第2驅動脈衝P2之關斷期間之際， 係糟由充電於電容裔C2之電祷經由二極體D1而放電於光 源負載部12而持續LED17之點燈。 接著，根據第2圖至第6圖說明上述光源驅動裝置10 之驅動操作順序。在光源負载部12之電極端子16間連接 LED17之後，啟動主電源使之導通。藉由此主電源之導通， 使信號處理控制部15内之CPU18重設，且使從此CPU18 輸出之開關控制信號成為0N。藉由此開關控制信號之ON， .關閉定電流脈衝驅動部13内之第2開關元件Q2。在此， 從前遂CPU輸出PWM信號並經由定電流控制部21而使第1 開關元件Q1成為0N，且將此ON狀態保持到電流檢測元件 R1之檢測電流成為1 ιπΑ為止。再者’在刖述電流檢測元件 R1檢測出1mA之時點鎖定（lock)PWM控制，且藉由電壓偵「 15 321383 201105167 測部26來讀取光源負載部12之電極端子16間之電壓值。 從在此所檢測出之電壓值，分出與則述光源負載部12連接 之LED17之驅動電力。在前述内’係從所儲存之計 算式算出額定電壓值VF、額定電流值1F及絕對最大額定 電流值I Pmax，且從此等設定乘佳之峰值電流值IP。另外， 此峰值電流值IP亦可如前所述’彳之可儲存於CPU18内之 VF—IF表單及IF—IPmax表單轉換。在前述峰值電流值IP 滿足如前述之關係式IFS Ipmax之範圍之中’尤其藉 由維持接近I Pmax之狀態，< 最大限度提高明亮度，同時 在穩定之狀態下使之發光。 如前所述，前述額定電壓值係可藉由使偵測電流 從微小值階段性施加於光源負载部12而從LED17之消耗電 力設定驅動條件。以下說明使用此偵測方法之具體例。最 初係藉由負載容量檢測部14檢測將從前述定電流脈衝驅 動部13所供給之1mA左右之微小電流流通於與光源負載部 12連接之LED17時之電壓值，且根據此電壓值而設定驅動 電流。在此，為了依據與光源負載部12連接之LED之種類 及數量來設定適當之驅動條件，因此先偵測所連接之led 之屬於負載容量之消耗電力，而設定驅動電流以與此消耗 電力匹配。如前所述’此LED之消耗電力，由於係使偵測 電流〜面從微小值階段性逐步提高一面進行，因此不會對 LED17造成無謂之負載，而可高精確度地進行偵測。從在 此所谓測之消耗電力，藉由信號處理控制部15算出適當之 額定電流值IF及峰值電流值ip。再者，在確定此等驅動 16 321383 201105167 條件之後，切換兔兹^ ^ 脈衝驅動_之時=2㈣之脈衝轉㈣。轉移至此 ,.^ ’、攸主電源導通之後數//秒左右，因 此不會忍識到待機時間。 ° 彳°號處理控制部15切換為脈衝驅動控制時， 虞由剧❿。號處理控制部15所算出之奪值電流值ip及 開關控制信號。 使弟2開關元件Q2以預定之時序開關 t 關斷。藉由此開關，對前述光源負載部施加發 光驅W2所產生之電流，該發光驅動波形W2係藉由 在決疋LED17之發光週期之第i驅動脈衝^之中更高速開 關之第2驅動脈衝p2所產纟。此發光驅動波形μ係以週 =ί·生重複V通期間與關斷期間之脈衝波為依據進行RC積 分之三^波’因此可抑制整體之消耗電力及發熱，同時可 在以較咼位準維持發光亮度之狀態下使LED連續驅動。 第7圖係為比較藉由習知之驅動方式與本發明之驅動 方式之LED發光時之消耗電力及發熱量者。在此，（a)係為 習知之驅動方式者，（b)係為本發明之驅動方式者。此比較 驗證係在輸出入電壓為Aci〇〇v，溫度為25.CTC、濕度為 43. 5%之周圍環境條件下進行。此外，發光亮度亦設定為相 同條件。如（a)所示’在習知之驅動方式中，係在連續流通 有效值（1〇^ = 0.45丸）4?=3.6¥之定電流時產生1.62($) 之消耗電力’且該時之LED所發出之熱係成為約115。(：。 為成為與此（a)相同之發光亮度，就以定電流脈衝驅動時之 一例而言，如（b)所示，設定為脈衝之峰值電流（ιρ = 2· 8A)、VF = 4V、ON工作週期比=〇. 1。此時之消耗電力係 17 321383 201105167 為1.12(W)，而LED所發出之熱係為約6〇t>c。 從上迷第7圖之實驗結果可得知，依據本發明之LED 驅動方式’電力比率相較於習知方式，係可降低至約69%， 而發熱量亦可抑制為大致—半左右。 此外’前述LED17係藉由來自外部之控制信號 (C0NT) ’來控制定電流脈衝驅動部a内之第1開關元件 Q1及第2開關元件Q2導通之寬度（工作週期比），或調整 RC積分電路27之RC時間常數及充放電電路30内之電容 器電容量等，藉此而可進行發光量及發光亮度等之調整。 綜上所述’依據本發明之光源驅動方法及光源驅動裝 置，係藉由高速開關峰值電流值ίρ之導通/關斷變化之脈 衝信號而非對前述光源負載侧連續供給與連接於光源負載 側之LED之特性或個數對應之定電流來進行LED發光控 制。因此，可發揮在維持LED之發光水準於一定之狀態下， s某求降低發熱及隨著此發熱所產生之消耗電力之有利之效 果。 以LED之特性而言，由於順向之額定電壓值νρ有因 為溫度上升而降低之傾向，因此習知之來自一般之定電流 源之輸出電壓若一定，會有流通於光源負載部之電流增 加，且前述額定電壓值VF隨之更為降低之問題，惟如^所 述，藉由定電流脈衝驅動部間歇性地開關對LED之通電萨 間，可獲得降低溫度上升之效果，同時還可獲得抑制作7 之變動之效果。 此外’尚具備檢測流通於光源負載部12之額定電壤 321383 18 201105167 值VF之負載容量檢測部14，可從信號處理控制部15内之 CPU18所具備之計算式或VF — IF表單、iF_ lpmax表單瞬 間獲得峰值電流值IP及絕對最大額定電流值IPmax，該峰 值電流值IP及絕對最大額定電流值丨⑽狀係在使主電源導 通之同時與連接於前述光源負載部12之LED17之特性及個 數對應。因此，不需預先算出與前述光源負載部12連接之 負載容量，只要將所需之让讥了連接於前述光源負載部 12，即可更適當且以更佳效率使led1?發光驅動。 與韵述光源負載部12連接之LED17係1個也可驅動， 而連接複數個時，亦可為串聯或並聯或串聯並聯混合者。 另外，在本實施形態中’雖係以LED為驅動對象，惟不限 定於LED，可由脈衝狀之定電流信號驅動之各種馬達、電 磁閥線圈、致動器（actuat〇r)等之感應性負載亦可作為驅 動對象。 【圖式簡單說明】 第1圖係為本發明之光源驅動方法之概略流程圖。 第2圖係為本發明之光源驅動裝置之區塊圖。 第3圖係為上述光源驅動裝置之驅動時序圖。 第4圖係為上述光源驅動裝置之輪出波形圖。 第5圖係為構成上述光源驅動裝置之一部分之充放電 電路之電路圖。 第6圖係為根據上述詳細流程圖之各部之時序圖。 第7圖係為比較LED發光時之消耗電力及發熱量之曲 線圖。 19 321383 201105167 第8圖係為顯示習知之LED驅動裝置之基本構成之電 【主要元件符號說明】 10 光源驅動裝置 11 12 光源負載部 13 14 負載谷1檢測部 15 16 電極端子 17 18 CPU 21 23 第1驅動電路 24 26 電壓偵測部 27 28 差動放大器 29 30 充放電電路 31 32 基準電壓源 C1 D1 二極體 11 IF 額定電流值 IP IPraax 絕對最大額定電流值 k 係數 L1 PI 第1驅動脈衝 P2 QO 半導體開關 Q1 Q2 第2開關元件 R0 R1 ' R2 電流檢測元件 R4 SW 開關控制信號 T1 T2 第2導通/關斷週期 VI 檢測電壓 VccFurther, Patent Document 3 discloses an apparatus for detecting an overcurrent in a case where a peak current in a load of an LED light source is connected to prevent a low voltage. Fig. 8 is a diagram showing the LED lighting circuit using the conventional method. (10) The lighting circuit is configured to include a current limiting resistor, an electric H conductor switch Q 〇, and a P control circuit. The current limit is a resistor that limits the current flowing through (10), and the other is connected. One of the series circuits is connected to the power supply line Vcc, and the system S is connected to the ground (GND) via the semiconductor switch Q. The PWM control open relationship is a function of supplying a pulse signal modulated by PWM to a gate of the semiconductor Q0 to turn on/off the semiconductor switch Q0 4 321383 201105167. Further, the driving conditions such as the driving timing of the connected light-emitting elements and the current value to be supplied are stored in a form (tab 1 e) in advance and set in accordance with the form. - [Patent Document 1] [Patent Document 1] Japanese Laid-Open Patent Publication No. JP-A-2006-227951 [Patent Document No. JP-A-2004-227951] DISCLOSURE OF THE INVENTION [Problem to be Solved by the Invention] However, when the lighting circuit shown in the above-mentioned Fig. 8 causes the LED to be lit for a long time, the LED itself generates heat due to the power consumed by the LED. As this heat generates a temperature rise, the rated voltage value VF decreases. When the lighting circuit is in this situation, 'because the power supply is controlled by the constant voltage', the voltage across the current limiting resistor R0 and the circuit current will rise with the decrease of VF, resulting in a change in the brightness of the LED. The problem. Further, the (10) resistance of the semiconductor switch Q 亦 also changes due to the heat generation of the semiconductor switch Q , , and as a result, the same problem as the temperature rise of the LED occurs. Further, when the supply voltage fluctuates, there is a case where it directly changes to a change in the current value, which is a cause of a change in the luminance of the LED. In particular, the VF of the LED of the semiconductor has a large difference due to manufacturing variations of the lot, and therefore, when a plurality of ribs are connected to the load side, it is not easy to maintain a certain luminance. Make it shine continuously. 321383 5 201105167 In addition, although the light-emitting element is generally driven by a pulse formed by turning on/off at a certain period, the pulse is not more finely pulsed during the on-time of the on/off period of the certain period. Further, this pulse is controlled while maintaining the vicinity of the peak current value of the limit value of the driving ability of the light-emitting element. Accordingly, an object of the present invention is to provide a light source driving method and a light source driving device that can calculate a peak current value of a connected light-emitting element, and define an on-period of the light-emitting element based on the peak current value, and during the on-time period The maximum amplitude of the medium pulse is the peak current value, and the duty cycle ratio (dutyrat) of the on period and the off period is made variable, whereby power consumption can be suppressed and high-luminance and stable light emission can be obtained. [Solution to Problem] In order to solve the above problem, the light source driving method of the present invention includes the steps of: supplying current to a load side of a light source connected to a light-emitting element while detecting current, and detecting a rated voltage value; calculating from the rated voltage value An absolute maximum rated current value inherent to the light-emitting element, and a peak current value circulated to the light-emitting element is calculated within a range not exceeding the absolute maximum rated current value; and an on-period of the light-emitting element is specified according to the peak current value And generating a second driving pulse formed by a first on/off cycle in which a duty ratio of the on period and the off period is set to be variable; further switching is performed in an on period of the first driving pulse (switching), the maximum amplitude of the pulse is the peak current value, and the duty ratio of the on-period and the off-period is set to be the second drive pulse of the shape of 6321388 201105167 and the second conduction/_cycle; And applying a current driven by the =2 driving pulse to the load side of the light source to connect the light emitting element Acting light drive. Further, the light source driving device of the present invention comprises: a light source loading portion, a vertical light emitting element 'load capacity detecting portion, and detecting a rated voltage value of the light emitting element by supplying the light source load=current; signal processing control: ", the root j is calculated from the rated voltage value detected by the load capacity detecting unit. · (4) The rated current value of the steady state driving of the optical element and the absolute maximum 骇 current value when the light emitting element is calculated from the rated value, and = Exceeding the range of (4) the maximum rated current value (4), calculating and setting the value of the buzzer current of the light-emitting element; and driving the constant current pulse: the pulse width modulation is performed according to the peak current value, thereby generating a borrowing And determining a first driving pulse 'the square of the ith turn-on/turn-off period during the on period of the light-emitting element; and by performing a switch in the process of the first drive pulse The second driving pulse is formed by making the maximum vibration of the pulse = the peak current value 'and the second conduction/turn-off period in which the ratio of the on-time and the off-period is set to be variable. The driven current is applied to the light-emitting element to be continuous with the light-emitting element connected to the carrier (the effect of the invention). The light source driving method of the present invention is controlled by the source side of the light source in the initial detection connection. The rated voltage value, and from the rated voltage value, the absolute maximum rated current value inherent in the device can be set to maximize the current value of the light-emitting characteristic value of the light-emitting element in the steady state of 321383 7 201105167. Based on the peak current value, the maximum amplitude of the pulse is changed to the peak electric power and the value of the peak value by performing the ____ from the first conduction state of the predetermined light-emitting element. The duty ratio of the on-period and the off-period is set to be variable: the second drive pulse 'and the current driven by the second drive pulse is applied to the light source negative, and the light-emitting element is stably and continuously driven to emit light, and It is possible to reduce the overall power consumption. x In addition, the light source driving device according to the present invention has a chirp to detect the light connected to the load side of the light source in advance. The means for the load capacity of the component, and the signal processing (four) portion of the light-emitting element can be used to directly drive the light-emitting element = drive pulse from the peak current value calculated from the load capacity. The driving ability of the unit is reduced to a certain amount of heat and power consumption. [Embodiment] Hereinafter, the implementation of the light source driving method and the light source driving device of the present invention will be described in detail based on the drawings. The schematic flow of the light source driving method of the present invention (4), and Fig. 2 is a view showing the overall configuration of the light source driving device 10 of the present invention. As shown in Fig. 1, the light source driving method of the present invention is when the power source is turned on (0N). The rated voltage value VF of the single or a plurality of light-emitting elements (LEDs) 17 connected to the light source load portion 12 is detected (step_1; ^), when the detection is performed, the light source load portion 12 is stepped up from a small value. The current is measured while applying a voltage applied between one of the light source load portions 12 to the electrode terminals and 16. The detection current is obtained by reading a voltage value when the voltage between the electrode terminals "321383 8 201105167 becomes stable in a state of being positioned, and obtaining a rated voltage value VF from the reading result. Next, in the signal processing control unit The CPU 18 in 15 calculates the rated current value IF required for driving the LED 17 in steady state from the rated voltage value VF detected in the step-1. Further, the rated current value (IF) is calculated without destroying the LED 17 The absolute maximum rated current (IPmax) that can be circulated in the range (step-2). These rated current values (IF) and absolute maximum rated current values (IPmax) are based on pre-stored calculations in the memory of the CPU 18. The peak current value I'PCIFS IPClPmax) required to drive the LED 17 at a high efficiency is actually calculated from the calculation result (step-3). Next, it is generated based on the peak current value IP set in step-3. A square illumination period signal (first drive pulse) P1 (steps 4 and 3) for driving the LEDs 17 to be pulsed. The first drive pulse P1 is the first continuous pulse width modulation by the CPU 18. On/off The period T1 is a period in which the current is continuously repeated (on-period) and a period during which the current does not flow (off period). For example, the first on/off period T1 is set to be about 200 Hz, and the duty ratio is The on-period is 1 and the off-period is 9. The T1 is appropriately set in accordance with the driving ability of the LED 17. The first drive pulse P1 is generated by high-speed switching during the first on-period. a rectangular light-emission drive signal (second drive pulse) P2 (step-5) formed by the second on/off cycle T2 during the period of the current flowing, and the second on/off cycle T2 is in the foregoing For example, in the case of T1, it is set to about 300 kHz, and the operation is 9321383. The ratio of 201105167 is the same as that of the first drive pulse P1, and the on-period is 1 and the off-period is 9. The second drive pulse P2 is as described above. Similarly, the first drive pulse P1 sets the maximum amplitude and duty cycle ratio of the pulse based on the peak current value IP set by the drive capability such as the type and number of the LEDs 17. The current driven by the second drive pulse P2 The light is applied to the light source load side, whereby the LED 17 is driven to emit light (step-6). Further, as shown in Fig. 4, the second drive pulse P2 is passed through the RC integration circuit 27, thereby being turned on/in the second conduction/ In the turn-off period T2, the triangular-wave-shaped light-emission drive waveform W2 is repeatedly charged and discharged. Further, from the pulse formed by the light-emission drive waveform W2, a triangular wave shape which is repeatedly charged and discharged by the first on/off period T1 is outputted. The current generated by the illumination period waveform W1. In this manner, by applying the current generated by the illumination period waveform W1 having the peak current value IP to the maximum amplitude width to the LED 17 connected to the light source load side 12, power consumption can be suppressed, and the LED 17 can be continuously stabilized with high efficiency. The light is driven in the state. Fig. 2 is a view showing an example of the configuration of a light source driving device for realizing the above-described light source driving method. The light source driving device 10 is configured to include a constant current pulse driving unit 13, a load capacity detecting unit 14, and a signal processing control unit 15 between the power supply source 11 and the light source load unit 12. The power supply source 11 has any of an AC global input, a DC input, and a battery input, and serves as a constant voltage source for the constant current pulse driving unit 13. The light source supporting portion 12 is provided with a pair of electrode terminals 16, and a single or a plurality of LEDs 17 are connected between the electrode terminals 16. The signal processing control unit 15 includes a CPU 18, and the CPU 18 stores therein a voltage value (VF) of the LED 17 calculated from the voltage value applied between the electrode terminals 16, a rated current of 10321383, a 201105167 value (IF), and an absolute maximum. The rated current value (IPmax) and the calculation formula for the peak current value (IP) that is most suitable for driving. In the signal processing control unit 15, a detection current setting unit -29' is provided for detecting the load capacity (w) for detecting the light source source portion 12 from the power supply source 11 while controlling. Measuring current. In order to change the current supplied from the power supply source 11 stepwise from a small value, the detection current setting unit 29 includes, for example, a power corresponding to an LED corresponding to a minimum from a maximum of 1 mA to a maximum of 1 mA. (w) and a conversion form based on the rated voltage value of this power. When the light source driving device is activated, the front-end conversion form is sequentially supplied from the lower current value to the light source load portion 12, and the voltage value of the LED 17 is sequentially detected, and the item is taken. When the voltage value is stable, the standard power (w) of the LED 17 is detected, and the rated electric value (VF) required for continuously emitting the (10) 17 is set based on the detected power value. The peak current value IP based on the rated voltage value VF is obtained by multiplying the most uniform current value (IPmax) by a predetermined coefficient, and the coefficient k is used to specify the amount of illuminance, for example, If it is set to 0.9, high-brightness illumination near j IPmax can be known. This coefficient k can be set as long as it is not more than 1 (® <k<1), and thus can be set - the amount of illumination of the positive LED. In addition, the setting of the coefficient k is a variable resistor, a trimmer or a DIp switch connected to the external terminal (C0NT) of the light, the driving device 10, and the like. Set from the outside. In the case of "peak current value I p", the 321383 11 201105167 rated current value reference form (VF-IF form) and the absolute maximum rated current value reference form (IF-IPmax form) can be memorized in the CPU 18 first. The memory is calculated by the program processing based on the reference form. In the aforementioned VF_IF form, the rated voltage value VF and the rated current value IF' based on the power value detected by the LED 17 connected to the light source load portion 12 are set in the if-ipmax form, and the above-mentioned rating is set. The absolute maximum current value Ipmax corresponding to the current value IF. Here, the rated voltage value VF refers to a voltage value that allows the LED 17 connected to the light source load port 12 to emit light to a certain degree of brightness in a stable state, and the rated current value IF is such that it flows through the LED 17 at this time. value. In addition, the absolute maximum rated current value ipmax is the maximum allowable value for the operation of the LED 17 under certain conditions. If it exceeds this value, the component is destroyed. Therefore, it is specified as a value that does not exceed even in a short period of time. On the other hand, the peak current value IP in the present invention refers to the range of the above rated current value IF and not exceeding the absolute maximum rated current value IPmax (IFS IP < IPmax) 'Pulse and body control in such a manner as to maintain this range . Further, the rated voltage value VF and the rated current value IF vary depending on the number of the LEDs 17 and the connection form or the brightness to be set. In the light source driving device 1 of the present invention, the signal processing control unit is and the constant current pulse driving unit 13 control the peak current value IP within a range satisfying the relationship of IF$ Ip < IPmax, and the peak current value is made. Jp is constructed in a predetermined duty cycle ratio. - As shown in Fig. 2, the constant current pulse driving unit 13 includes a 疋 current control unit 21, a first switching element qi, current detecting elements R1, 12321383 201105167', and a second switching element Q2. The constant current control unit 21 is controlled so as to constantly monitor the current value II flowing through the light source load unit 1.2 and always supply it. The constant current control unit 21 includes a buck-boost converter (not shown), and increases or decreases the current level from the power supply source 11 to fill the current flowing through the LED 17 connected to the light source load unit 12. Increase or decrease of value II. Thereby, a certain current level is maintained. The first switching element Q1 is configured to generate a first driving pulse P1 composed of the first on/off cycle T1, and the current increased or decreased by the buck-boost converter at a predetermined timing via the first driving circuit 23. The signal is switched, thereby setting the ratio of the on-time to the off-period (duration ratio). The first on/off period T1 is controlled to be about 200 Hz. Further, although the duty ratio is controlled such that the LED 17 has a rated luminance, by setting the on period to about 50% or less, the amount of heat generation and power consumption can be reduced. In the present embodiment, the duty cycle ratio is also set such that the on period is 10% and the off period is 90%. The current detecting element R1 is connected in series to the input side of the light source load unit 12 for detecting a current value flowing through the current detecting element R1 and feeding back to the constant current control unit 21. The second switching element Q2 is for generating the second driving pulse P2 composed of the second on/off period T2, and can operate during the period in which the first switching element Q1 is turned on. The second switching element Q2 is switched at a high speed in accordance with the switching control signal SW from the signal processing control unit 15 via the second drive circuit 24. With this switch, the second on/off period T2 is controlled to 300 kHz, the duty cycle is 10% during the on period, and the off period is 90%. 13 321 383 201105167 The constant current pulse driving unit 13 is provided with a charge and discharge circuit 3Q composed of an inductor (coil), a pixel container C, and C2, on the output side connected to the negative electrode terminal 16 of the light source. In the charging/discharging circuit, the first switching element Q1 and the second switching element Q2 are turned on, and the current of the zero-pass LED 17 is also charged to the capacitor c2. Further, during the period in which the "th flow element Q1" and the second switching element Q2 are turned off, the charge charged in the capacitor switch is discharged, and current is caused to flow through the LED 17. Thereby, not only the respective conduction periods 1 of the switches of the = switching element Q1 and the second switching element Q2 can continuously supply a certain amount of current to the LEDs 17 even during the off period. a 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 Further, the coil L1 and the capacitor are provided in order to smooth the peak current value IP flowing through the LED 17 due to the conduction of the second switching element Q2. As shown in Fig. 2, the load capacity detecting unit 14 includes an electric power detecting element R2, an RC integrating circuit 27, and a differential amplifier. The electric detecting element R2 uses a high-accuracy shunt resistor (shun^, resistance) to detect a current flowing through the LED 17 by the switch of the second switching element. In the RC integrating circuit 27, the detected current detected by the current detecting element is integrated by the on/off period of the first switching element Q2. The differential amplifier 28 takes the difference between the signal integrated by the RC integrating circuit 27 and the reference voltage source 3, and amplifies it, and outputs the amplified detection voltage VI. This detection power is supplied to the signal processing control unit 15. 321383 14 201105167 Fig. 5 is a configuration example when the protection circuit 31 is provided in the above-described charge and discharge circuit 30. The protection circuit 31 is composed of a limiting resistor R4 for limiting the charging current to the capacitor C2 and a rectifying element (diode) D1 for bypassing the discharging current, thereby preventing the light source from being negative. - The electrode terminal 16 of the carrier 12 flows a current when the LED 17 is connected in a state where the electrode terminal 16 is open and the main power source of the light source driving device 10 is turned on. According to the protection circuit 31, in the on period of the second drive pulse P2 generated by the switching of the second switching element Q2, the smoothing of the peak current value IP by the capacitor C1 and the coil L1 is started simultaneously with the capacitor C2. The charge is made while the LED 17 is lit. At this time, the limiting resistor R4 has a function of preventing the current from entering the capacitor C2 and limiting the charging current. Further, when shifting to the off period of the second drive pulse P2, the electric charge is charged to the light source load portion 12 via the diode D1 by the electric charge charged to the capacitor C2, and the LED 17 is turned on. Next, the driving operation sequence of the above-described light source driving device 10 will be described based on Figs. 2 to 6 . After the LEDs 17 are connected between the electrode terminals 16 of the light source load portion 12, the main power source is turned on to turn on. By the conduction of the main power source, the CPU 18 in the signal processing control unit 15 is reset, and the switch control signal output from the CPU 18 is set to ON. The second switching element Q2 in the constant current pulse driving unit 13 is turned off by the ON of the switching control signal. Here, the PWM signal is output from the front CPU, and the first switching element Q1 is turned ON by the constant current control unit 21, and the ON state is held until the detection current of the current detecting element R1 becomes 1 ππΑ. In addition, when the current detecting element R1 detects that 1 mA is detected, the PWM control is locked, and the voltage value between the electrode terminals 16 of the light source supporting portion 12 is read by the voltage detecting unit 15 321383 201105167. From the voltage value detected here, the driving power of the LED 17 connected to the light source load unit 12 is divided. In the above, the rated voltage value VF, the rated current value 1F, and the absolute maximum are calculated from the stored calculation formula. The rated current value I Pmax, and the peak current value IP is set from the above. In addition, the peak current value IP can also be converted into the VF-IF form and the IF-IPmax form stored in the CPU 18 as described above. In the range where the peak current value IP satisfies the relationship IFS Ipmax as described above, 'in particular, by maintaining a state close to I Pmax , < maximizing brightness while causing it to emit light in a stable state. As described above, the rated voltage value can be set from the power consumption of the LED 17 by applying the detection current from the minute value to the light source load unit 12 in a stepwise manner. The following describes the specific use of the detection method. First, the load capacity detecting unit 14 detects a voltage value when a minute current of about 1 mA supplied from the constant current pulse driving unit 13 flows through the LED 17 connected to the light source load unit 12, and sets the voltage value based on the voltage value. Here, in order to set an appropriate driving condition according to the type and number of LEDs connected to the light source load unit 12, firstly, the power consumption of the connected led device belonging to the load capacity is detected, and the driving current is set. Power consumption matching. As mentioned above, the power consumption of this LED is performed because the detection current ~ surface is gradually increased from a small value step by step, so that the LED 17 is not subjected to unnecessary load, and can be performed with high precision. Detection: From the power consumption measured here, the signal processing control unit 15 calculates an appropriate rated current value IF and peak current value ip. Further, after determining the conditions of the driving 16 321383 201105167, switching the rabbits ^ ^ Pulse drive _ time = 2 (four) pulse turn (four). Transfer to this, .^ ', 攸 main power supply after the number of / / seconds, so will not endure standby When the 处理° processing control unit 15 switches to the pulse drive control, the capture current value ip and the switch control signal calculated by the program control unit 15 are turned on. The switching element Q2 is switched at a predetermined timing. Turning off, the current generated by the illuminating drive W2 is applied to the light source load portion by the switch, and the illuminating driving waveform W2 is switched at a higher speed by the ith driving pulse φ in the illuminating period of the LED 17 The second driving pulse p2 is generated by the second driving pulse μ. The IGBT is integrated with the pulse wave of the cycle during the V-pass period and the off period, thereby suppressing the overall power consumption and When the heat is generated, the LED can be continuously driven while maintaining the light-emitting brightness at a relatively high level. Fig. 7 is a graph showing the power consumption and the amount of heat generated when the LEDs of the driving method of the present invention are driven by the conventional driving method and the driving method of the present invention. Here, (a) is a conventional driving method, and (b) is a driving method of the present invention. This comparison was carried out under ambient conditions with an input voltage of Aci〇〇v, a temperature of 25. CTC, and a humidity of 43.5%. In addition, the luminance of the light is also set to the same condition. As shown in (a), in the conventional driving method, 1.62 ($) of power consumption is generated when a constant current (1〇^ = 0.45 pills) 4?=3.6 yen is continuously flowed, and at that time, The heat generated by the LED is about 115. (: In order to achieve the same luminance as that of (a), when driving with a constant current pulse, as shown in (b), set the peak current of the pulse (ιρ = 2·8A), VF = 4V, ON duty cycle ratio = 〇. 1. At this time, the power consumption is 17 321383 201105167 is 1.12 (W), and the heat generated by the LED is about 6 〇 t > c. From the above experimental results of Figure 7 It can be seen that the LED driving method according to the present invention has a power ratio lower than that of the conventional method, and can be reduced to about 69%, and the heat generation can be suppressed to approximately - half. The control signal (C0NT)' controls the width (duty cycle ratio) at which the first switching element Q1 and the second switching element Q2 in the constant current pulse driving unit a are turned on, or adjusts the RC time constant and charge and discharge of the RC integrating circuit 27. The capacitance of the capacitor in the circuit 30, etc., thereby adjusting the amount of light emitted, the brightness of the light, etc. In summary, the light source driving method and the light source driving device according to the present invention are characterized by high-speed switching peak current value ίρ Turn on/off the pulse signal instead of the pair The light source load side continuously supplies a constant current corresponding to the characteristics or the number of LEDs connected to the light source load side to perform LED light emission control. Therefore, it is possible to reduce the heat generation while maintaining the light emission level of the LED in a certain state. And the beneficial effect of the power consumption caused by the heat generation. In terms of the characteristics of the LED, since the forward rated voltage value νρ tends to decrease due to the temperature rise, the conventional output from the constant current source is conventionally known. If the voltage is constant, there is a problem that the current flowing through the load portion of the light source increases, and the rated voltage value VF is further reduced. However, as described in the above, the constant current pulse driving portion intermittently switches the LED to be energized. In the case of the sa, the effect of reducing the temperature rise can be obtained, and the effect of suppressing the variation of the change 7 can be obtained. Further, the load capacity detecting unit 14 for detecting the rated voltage 321383 18 201105167 value VF flowing through the light source load portion 12 is provided. The peak current value IP and the absolute maximum can be obtained instantaneously from the calculation formula or the VF-IF form and the iF_lpmax form of the CPU 18 in the signal processing control unit 15. The rated current value IPmax, the peak current value IP and the absolute maximum rated current value 丨(10) are related to the characteristics and the number of the LEDs 17 connected to the light source load unit 12 while the main power source is turned on. Therefore, it is not necessary to calculate in advance. The load capacity connected to the light source load portion 12 can be more appropriately and more efficiently driven to be led to the light source load portion 12. The light source load portion 12 can be connected to the rhythm light source load portion 12 as long as it is connected to the light source load portion 12. One of the LED17 series can also be driven, and when a plurality of LEDs are connected, they can also be mixed in series or in parallel or in series and in parallel. In addition, in the present embodiment, the LED is the driving target, but is not limited to the LED, and the inductance of various motors, solenoid valve coils, and actuators (actuator) that can be driven by a pulsed constant current signal can be used. The load can also be used as a drive object. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic flow chart of a light source driving method of the present invention. Fig. 2 is a block diagram of a light source driving device of the present invention. Fig. 3 is a driving timing chart of the above-described light source driving device. Fig. 4 is a waveform diagram of the above-described light source driving device. Fig. 5 is a circuit diagram of a charge and discharge circuit constituting a part of the above-described light source driving device. Fig. 6 is a timing chart of each part according to the above detailed flowchart. Fig. 7 is a graph comparing the power consumption and the amount of heat generated when the LED is illuminated. 19 321383 201105167 Fig. 8 is a diagram showing the basic configuration of a conventional LED driving device. [Main component symbol description] 10 Light source driving device 11 12 Light source load portion 13 14 Load valley 1 detecting portion 15 16 Electrode terminal 17 18 CPU 21 23 First drive circuit 24 26 Voltage detection unit 27 28 Difference amplifier 29 30 Charge and discharge circuit 31 32 Reference voltage source C1 D1 Diode 11 IF Rated current value IP IPraax Absolute maximum rated current value k Coefficient L1 PI 1st drive pulse P2 QO semiconductor switch Q1 Q2 second switching element R0 R1 ' R2 current detecting element R4 SW switching control signal T1 T2 second on/off period VI detection voltage Vcc
電力供給源 定電流脈衝驅動部 信號處理控制部 LED 定電流控制部 第2驅動電路 RC積分電路 偵測電流設定部 保護電路 ' C2電容器 電流值 峰值電流值 線圈 第2驅動脈衝 第1開關元件 電流限制電阻器 限制電阻器 第i導通/關斷週期 電源線 321383 20 201105167 VF 額定電壓值 W2 發光驅動波形 wi 發光週期波形 21 321383Power supply constant current pulse drive unit signal processing control unit LED constant current control unit second drive circuit RC integration circuit detection current setting unit protection circuit 'C2 capacitor current value peak current value coil second drive pulse first switching element current limit Resistor limiting resistor ith turn-on/turn-off cycle power supply line 321383 20 201105167 VF rated voltage value W2 illuminating drive waveform wi illuminating period waveform 21 321383