200803623 九、發明說明： 【發明所屬之技術領域】 本發明涉及一種照明電路。 【先前技術】 習知技術中，利用一些產生脈寬調製波（PWM波）的 晶片驅動發光體時，晶片輸出PWM波的引腳會由於某些 原因產生故障，加電後會一直處於高電平狀態，因此，晶 片相當於輸出占空比為100%的PWM波驅動發光體。致使 發光體一直處於高亮度狀態，此時，若用戶未開關該照明 電路，其無法儘快獲知控制單元故障情況，無法儘快維修， 導致電能過度消耗。 【發明内容】 有鑒如此，提供一種照明電路，以解決先前技術中用 戶無法儘快獲知照明電路故障的問題。 其中，所述照明電路包括一連接至一電源的發光單 元，所述發光單元包括多個並聯的發光支路，所述發光支 路由一控制單元輸出脈寬調製波控制一開關電路導通截止 來控制’所述脈寬調製波輸出至一微分電路並經該微分電 路微分以產生尖脈衝波控制所述開關電路。 所述照明電路還包括一電勢提升電路，用於提升尖脈 衝波的電勢。 所述照明電路還包括一取樣電路，所述取樣電路獲取 發光單元的實際亮度資訊，並將該實際亮度資訊回饋回控 制單元，所述控制單元根據所述實際亮度資訊調節輸出脈 6 200803623 寬調製波的占空比。 每一發光支路包括一發光體以及與一發光體串接的阻 性元件，所述阻性元件平衡各發光支路的阻值。 【實施方式】 請參閱圖1，是一利用本發明照明電路的電子裝置一 示意圖。所示電子裝置為一便攜式無紙書i。所述便攜式 無紙書1包括一顯示區11與一按鍵區12。所述顯示區U 周圍區域13殼體内部裝設有多個發光體14。所述發光體 14發出亮光經由一導光板（未示出）照亮顯示區1：1。使用 戶在黑暗％丨兄中仍能閱項該便攜式無紙書1所顯示資料。 請參閱圖2及圖3,是本發明照明電路一具體實施方 式的電路框圖與部分開關連接示意圖。包含發光體14的發 光單元7利用一控制單元3產生脈寬調製波（pwM波）來 控制發光亮度。所述發光單元7與所述控制單元3均從一 直流電源（VDD) 2處接受電能供應。所述控制單元3主 要包括有：一 VDD輸入口 301，用於從直流電源2處接受 直流電能供應控制單元3内各部分利用；一 pwM輸出口 302，用於輸出具一定占空比的pwM波控制發光單元7的 發光亮度；一 VSS輸入口 303，與一公共低電勢（如圖所 不為一地電勢）相連；一回饋輸入口 3〇4，與一取樣電路8 相連，用於接收該取樣電路8獲取的發光單元7的實際亮 度資訊，一環境光感測輸入口 305，與一環境光感測單元9 相連’接收環境光感測單元9感測的環境光強度值；一發 光開關輸入口 306，與一發光開關單元1〇2相連，用於接 7 200803623 收用^作發光開關單元1G2產生的照明電路開關命令； 及儿度選取輪入口 307，與一亮度選取單元1〇3相連， 用於^收用戶操作亮度選取單元1G3選取的亮度訊號。該 冗度^取單凡103、發光開關單元102以及一環境光感測 ，關，元1〇1共同組成一供用戶控制照明電路的用戶控制 單兀二10，該用戶控制單元組10設置於便攜式無紙書1 的外=上’例如設置於便攜式無紙書1的按鍵d 12，便於 操作°技境光感測開關單元10用於用戶根據需要開關 沐i兄光感測單兀9。在本實施方式中，環境光感測開關單 元1〇^鉗制發光開關單元102產生開關開關照明電路的命 令，=用戶操作環境光感測開關單元101啟動環境光感測 單兀感測環境光，以使控制單元3自動根據環境光強度值 開關與調_發光單元7的發光亮度時，照明電路已處於自 動控制的狀態’此時操作發光開關單元102無法產生開關 照明電路的命令；反之，當根據需要選取通過發光開關單 元102開關照明電路時，需先利用環境光感測開關單元ι〇1 關閉環境光感測單元9。在另一實施方式中，也可利用發 光開關單元102钳制環境光感測開關單元ιοί，此時只有 在利用發光開關單元102關閉照明電路後，才能利用環境 光感測開關單元101啟動環境光感測單元9,使控制單元3 自動控制照明電路。此外，發光開關單元102亦控制亮度 選取單元103，在發光開關單元1〇2啟動照明電路後，用 戶才可通過亮度選取單元103輸入亮度訊號。 從PWM輸出口 302輸出的PWM波經一微分電路4與 200803623 一電位提升電路5後以—開_路6，控制該開關電路6 的與戴止。該開關電路6的導通與戴止又進—步控制 發光單元7經取樣電路8後與—公共低電勢，如圖所:為 -地電勢的連接’從而控制發光單元7的發光亮度。 月乡閱圖4所示’是控制單元3的具體框圖。控制單 -^括開關模、组祀，該開關模組祀接收從環境光感 測輸入π 305輸入的環境光強度值與從發光開關輸入口 3〇2輸人的開關照明電路的命令，當所接㈣環境光強度 值低於某—預設水準時，或者接收到開照明電路的命令 時丄該開關模組311輸出訊號啟動一亮度選取模組31〇。 S 、取模組31〇接收從環境光感測輸入口；305輸入的 強錄或從亮度選取輸人口衞輸人的亮度訊號， “根康该％境光強度值或亮度訊號從—存儲單元通内選 取相應的預設亮度，根據該預設亮度轉-PWM產生電 路309產生具相應占空比的PWM波。在本實施方式中， 根據需要在存儲單元3〇8内預存有n (其中n為大與丄的 自然數）個預設亮度值，另，在存儲單元3G5内還預存有 η個壤境光強度區間，該n個環境光強度區間與n個預設 亮度值一一對應。當亮度選取模組310所接收的環境光強 度值落入η個環境光強度區間中某一個環境光強度區間 時’亮度選取模組310選取與該環境光強度區間相對應的 預設亮度值，利用該預設亮度值控制PWM產生電路309 產生具相應占空比的PWM波，從而達到控制發光單元7 發出接近預設亮度值亮度的亮光。此外，利用亮度選取單 9 200803623 元103選取預設亮度時，根據用戶操作的不同，該亮度選 取單元103可產生η種亮度訊號，該等党度訊號與存儲單 元308内預存的η個預設亮度值一 一對應。當焭度選取模 組310從亮度選取輸入口 307接收到一亮度訊號時，其在 存儲單元308内選取與該亮度訊號相對應的預設亮度值， 利用該預設亮度值控制發光單元7發出接近預設亮度值亮 度的免光。 當開關模組311接收從發光開關輸入口 302輸入的開 照明電路的命令啟動亮度選取模組310後，若亮度選取模 組310未從亮度選取輸入口 307接收到任何亮度訊號，則 亮度選取模組310在存儲單元308内選取一默認預設亮 度，利用該默認預設亮度值控制發光單元7發出接近默認 預設亮度值亮度的亮光。 PWM產生電路還接受從回饋輸入口 304輸入的發光單 元7的實際亮度資訊，並將該實際亮度值與預設亮度值比 較，根據比較結果來調節產生PWM波的占空比，最終控 制發光單元7的實際亮度值接近甚至等於預設亮度值。 請參閱圖5所示，是圖2所示照明電路中部分具體電 路圖。在該具體電路圖中，發光單元7包括多個並聯於直 流電源2與開關電路6之間的發光支路LI、L2…Ln。每一 發光支路Ln包括一發光體14 (如圖4所示為一發光二極 體）與一與該發光體14串接的阻性元件15，所述阻性元 件15平衡各發光支路Ln的阻值。所述開關電路6例舉為 一 MOS管S，所述MOS管S汲源兩極連接于發光單元7 200803623 ' 與取樣電路8之間，閘極連接於微分電路4。所述取樣電 • 路8由一小阻值阻性元件R2串接於開關電路6與公共低電 勢（地電勢）之間構成。發光單元7的實際亮度資訊經由 阻性元件R2連接開關電路8的一端回饋至控制單元3的回 饋輸入口 304。所述微分電路4由一容性元件C與一阻性 元件R1構成，所述容性元件C連接於PWM輸出口 302 與開關電路6閘極之間，阻性元件ri連接於開關電路6 閘極與公共低電勢（地電勢）之間。所述電位提升電路5 包括一二極體D，所述二極體D陰極連接開關電路6閘極， 陽極連接公共低電勢（地電勢）。從PWM輸出口 302輸出 的矩形PWM波經微分電路4微分後產生尖脈衝波，該尖 脈衝波經電位提升電路5提升電勢後進入開關電路6，控 制開關電路6導通截止。 在使用中，當控制單元3内部或PWM輸出口 3〇2處 產生故障，導致PWM輸出口 302持續輸出高電平（即輪 出占空比為100%的PWM波）時，此時發光單元7會_直 處於高亮度的狀態。若用戶未開關該照明電路，並且也未 調節發光單元7的亮度，因而無法儘快獲知控制單元故障 情況，無法儘快維修，導致電能過度消耗。利用微分電= 4，若控制單元3產生故障，其PWM輸出口 3〇2持續輸出 咼電平，則由於微分電路4對該pwm輸出口 302輸出 波的微分作用，發光單元7點亮後迅速熄滅，自動通知用 戶控制單元3處於故障狀態，達到節能的目的。 【圖式簡單說明】 11 200803623 圖1是一利用本發明照明電路的電子裝置一示意圖。 圖2是本發明照明電路一具體實施方式的電路框圖。 圖3是圖2所示照明電路部分開關連接示意圖。 圖4是圖2所示照明電路中控制單元的一具體框圖。 圖5是圖2所示照明電路中部分具體電路圖。 【主要元件符號說明】 便攜式無紙書 1 顯不區 11 按鍵區 12 周圍區域 13 發光體 14 直流電源 2 控制單元 3 微分電路 4 電位提昇電路 5 開關電路 6 發光單元 7 取樣電路 8 環境光感測單元 9 用戶控制單元組 10 環境光感測開關單元 101 發光開關單元 102 亮度選取單元 103 VDD輸入口 301 12 200803623200803623 IX. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to a lighting circuit. [Prior Art] In the prior art, when a wafer is used to generate a pulse width modulated wave (PWM wave) to drive an illuminator, the pin of the PWM output of the chip may be faulty for some reasons, and will always be in a high voltage after being powered on. In the flat state, therefore, the wafer corresponds to a PWM wave driving illuminator having an output duty ratio of 100%. The illuminant is always in a high-brightness state. At this time, if the user does not switch the lighting circuit, it cannot know the failure of the control unit as soon as possible, and cannot be repaired as soon as possible, resulting in excessive consumption of electric energy. SUMMARY OF THE INVENTION In view of the above, a lighting circuit is provided to solve the problem that the prior art cannot know the malfunction of the lighting circuit as soon as possible. Wherein, the lighting circuit comprises a lighting unit connected to a power source, the lighting unit comprises a plurality of parallel lighting branches, the lighting branch routing a control unit output pulse width modulation wave control, a switching circuit is turned on and off to control The pulse width modulated wave is output to a differential circuit and differentiated by the differentiating circuit to generate a sharp pulse wave to control the switching circuit. The illumination circuit also includes a potential boosting circuit for boosting the potential of the spike. The illumination circuit further includes a sampling circuit, the sampling circuit acquires actual brightness information of the light emitting unit, and feeds back the actual brightness information back to the control unit, and the control unit adjusts the output pulse according to the actual brightness information 6 200803623 wide modulation The duty cycle of the wave. Each of the illuminating branches includes an illuminant and a resistive element connected in series with an illuminant, the resistive element balancing the resistance of each of the illuminating branches. [Embodiment] Please refer to Fig. 1, which is a schematic diagram of an electronic device using the illumination circuit of the present invention. The electronic device shown is a portable paperless book i. The portable paperless book 1 includes a display area 11 and a button area 12. A plurality of illuminants 14 are mounted inside the casing 13 surrounding the display area U. The illuminator 14 emits bright light to illuminate the display area 1:1 via a light guide plate (not shown). The user can still read the data displayed in the portable paperless book 1 in the dark % brother. 2 and FIG. 3 are schematic diagrams showing a circuit block diagram and a partial switch connection of a specific embodiment of the lighting circuit of the present invention. The light-emitting unit 7 including the illuminator 14 uses a control unit 3 to generate a pulse width modulated wave (pwM wave) to control the light-emitting luminance. Both the light emitting unit 7 and the control unit 3 receive power supply from a direct current power source (VDD) 2. The control unit 3 mainly includes a VDD input port 301 for receiving various parts of the DC power supply control unit 3 from the DC power source 2, and a pwM output port 302 for outputting a pwM with a certain duty ratio. The wave controls the luminance of the light-emitting unit 7; a VSS input port 303 is connected to a common low potential (not shown as a ground potential); a feedback input port 3〇4 is connected to a sampling circuit 8 for receiving The actual brightness information of the light-emitting unit 7 obtained by the sampling circuit 8 is connected to an ambient light sensing unit 9 to receive an ambient light intensity value sensed by the ambient light sensing unit 9; The switch input port 306 is connected to an illuminating switch unit 1 〇 2 for receiving the lighting circuit switch command generated by the illuminating switch unit 1G2, and the illuminating unit 307, and a brightness selecting unit 〇 3 connected, used to receive the brightness signal selected by the user to operate the brightness selection unit 1G3. The redundancy control unit 103, the light switch unit 102, and an ambient light sensor, and the unit 1〇1 together constitute a user control unit 10 for the user to control the lighting circuit. The user control unit group 10 is disposed on the The outer=upper of the portable paperless book 1 is set, for example, to the button d12 of the portable paperless book 1, which is convenient for operation. The technical light sensing switch unit 10 is used for the user to switch the light sensing unit 9 as needed. In the embodiment, the ambient light sensing switch unit 1 clamps the light switch unit 102 to generate a switch switch lighting circuit command, and the user operates the ambient light sensing switch unit 101 to activate the ambient light sensing unit to sense the ambient light. In order to enable the control unit 3 to automatically switch the illumination brightness of the illumination unit 7 according to the ambient light intensity value, the illumination circuit is already in an automatically controlled state. At this time, the operation of the illumination switch unit 102 cannot generate a command to switch the illumination circuit; When the lighting circuit is switched through the light-emitting switch unit 102 as needed, the ambient light sensing unit 9 is first turned off by the ambient light sensing switch unit ι〇1. In another embodiment, the ambient light sensing switch unit ιοί can also be clamped by the illuminating switch unit 102. At this time, the ambient light sensing switch unit 101 can be used to activate the ambient light sensation only after the lighting circuit is turned off by the illuminating switch unit 102. The measuring unit 9 causes the control unit 3 to automatically control the lighting circuit. In addition, the illumination switch unit 102 also controls the brightness selection unit 103. After the illumination switch unit 1〇2 activates the illumination circuit, the user can input the brightness signal through the brightness selection unit 103. The PWM wave outputted from the PWM output port 302 is controlled by a differentiating circuit 4 and 200803623 to a potential boosting circuit 5, and the switching circuit 6 is controlled to be worn. The turn-on and turn-on control of the switch circuit 6 further controls the light-emitting unit 7 to control the light-emitting luminance of the light-emitting unit 7 via the sampling circuit 8 and the common low potential, as shown in the figure: the connection of the ground potential. The month shown in Figure 4 is a detailed block diagram of the control unit 3. The control unit includes a switch mode and a group switch, and the switch module receives the ambient light intensity value input from the ambient light sensing input π 305 and the command of the switch lighting circuit input from the light switch input port 3〇2 When the (4) ambient light intensity value is lower than a certain preset level, or when a command to open the lighting circuit is received, the switch module 311 outputs a signal to activate a brightness selection module 31. S, the module 31〇 receives the ambient light sensing input port; the 305 input strong record or the brightness signal selected from the brightness input, “Gencon the % ambient light intensity value or brightness signal slave-storage unit Selecting a corresponding preset brightness, and generating a PWM wave having a corresponding duty ratio according to the preset brightness-to-PWM generation circuit 309. In the present embodiment, n is pre-stored in the storage unit 3〇8 as needed (wherein n is a natural number of the big and the )) a preset brightness value, and in the storage unit 3G5, there are also pre-stored n light light intensity intervals, and the n ambient light intensity intervals correspond to n preset brightness values one by one. When the ambient light intensity value received by the brightness selection module 310 falls within one of the ambient light intensity intervals, the brightness selection module 310 selects a preset brightness value corresponding to the ambient light intensity interval. And using the preset brightness value to control the PWM generating circuit 309 to generate a PWM wave having a corresponding duty ratio, thereby achieving control of the brightness of the light emitting unit 7 to emit brightness close to the preset brightness value. In addition, using the brightness selection sheet 9 200803623 yuan 103 When the brightness is preset, the brightness selecting unit 103 can generate n kinds of brightness signals according to different operations of the user, and the party signals are in one-to-one correspondence with the n preset brightness values pre-stored in the storage unit 308. When the group 310 receives a brightness signal from the brightness selection input port 307, it selects a preset brightness value corresponding to the brightness signal in the storage unit 308, and controls the light-emitting unit 7 to emit a preset preset brightness value by using the preset brightness value. When the switch module 311 receives the command to open the illumination circuit input from the illumination switch input port 302 to activate the brightness selection module 310, if the brightness selection module 310 does not receive any brightness signal from the brightness selection input port 307 The brightness selection module 310 selects a default preset brightness in the storage unit 308, and uses the default preset brightness value to control the illumination unit 7 to emit brightness close to the default preset brightness value. The PWM generation circuit also accepts the feedback input port. 304, the actual brightness information of the light-emitting unit 7 is input, and the actual brightness value is compared with the preset brightness value, and the production is adjusted according to the comparison result. The duty ratio of the PWM wave is generated, and finally the actual brightness value of the light-emitting unit 7 is controlled to be close to or equal to the preset brightness value. Referring to FIG. 5, it is a partial circuit diagram of the lighting circuit shown in FIG. 2. In the specific circuit diagram, The light-emitting unit 7 includes a plurality of light-emitting branches LI, L2, ..., Ln connected in parallel between the DC power source 2 and the switch circuit 6. Each of the light-emitting branches Ln includes an illuminant 14 (as shown in Fig. 4, a light-emitting diode) And a resistive element 15 connected in series with the illuminant 14. The resistive element 15 balances the resistance of each of the illuminating branches Ln. The switching circuit 6 is exemplified by a MOS transistor S, and the MOS transistor S The two poles of the source are connected between the light-emitting unit 7 200803623' and the sampling circuit 8, and the gate is connected to the differential circuit 4. The sampling circuit 8 is formed by a small resistance resistive element R2 connected in series between the switching circuit 6 and a common low potential (ground potential). The actual luminance information of the light-emitting unit 7 is fed back to the feedback input port 304 of the control unit 3 via one end of the switching circuit 8 via the resistive element R2. The differential circuit 4 is composed of a capacitive element C and a resistive element R1 connected between the PWM output port 302 and the gate of the switch circuit 6, and the resistive element ri is connected to the switch circuit 6 Between the pole and the public low potential (ground potential). The potential boosting circuit 5 includes a diode D, the cathode of which is connected to the gate of the switching circuit 6, and the anode is connected to a common low potential (ground potential). The rectangular PWM wave outputted from the PWM output port 302 is differentiated by the differentiating circuit 4 to generate a sharp pulse wave. The sharp pulse wave is boosted by the potential boosting circuit 5 and then enters the switching circuit 6, and the switching circuit 6 is turned on and off. In use, when a fault occurs in the internal control unit 3 or the PWM output port 3〇2, causing the PWM output port 302 to continuously output a high level (ie, a PWM wave with a duty ratio of 100%), the light emitting unit at this time 7 will be _ straight in a state of high brightness. If the user does not switch the lighting circuit and the brightness of the light-emitting unit 7 is not adjusted, the failure of the control unit cannot be known as soon as possible, and the repair cannot be performed as soon as possible, resulting in excessive consumption of electric energy. With the differential power = 4, if the control unit 3 generates a fault and its PWM output port 3〇2 continues to output the 咼 level, the differential circuit 4 differentially acts on the output wave of the pwm output port 302, and the light-emitting unit 7 lights up rapidly. When it is turned off, the user control unit 3 is automatically notified that it is in a fault state, and the purpose of energy saving is achieved. BRIEF DESCRIPTION OF THE DRAWINGS 11 200803623 FIG. 1 is a schematic diagram of an electronic device using the illumination circuit of the present invention. 2 is a circuit block diagram of a specific embodiment of a lighting circuit of the present invention. Figure 3 is a schematic view showing the switch connection of the lighting circuit shown in Figure 2. 4 is a detailed block diagram of a control unit in the lighting circuit of FIG. 2. Fig. 5 is a partial circuit diagram of the lighting circuit shown in Fig. 2. [Main component symbol description] Portable paperless book 1 Display area 11 Key area 12 Surrounding area 13 Illuminant 14 DC power supply 2 Control unit 3 Differential circuit 4 Potential boost circuit 5 Switch circuit 6 Light-emitting unit 7 Sampling circuit 8 Ambient light sensing Unit 9 User Control Unit Group 10 Ambient Light Sensing Switch Unit 101 Light Switch Unit 102 Brightness Selection Unit 103 VDD Input Port 301 12 200803623
PWM輸出口 302 VSS輸入口 303 回授輸入口 304 環境光感測輸入口 305 發光開關輸入口 306 亮度選取輸入口 307 記憶模組 308 PWM產生電路 309 亮度選取模組 310 開關模組 311 發光支路 LI、L2、Ln 阻性元件 15、Rl、R2 容性元件 C 二極體 D 13PWM output port 302 VSS input port 303 feedback input port 304 ambient light sensing input port 305 light switch input port 306 brightness selection input port 307 memory module 308 PWM generation circuit 309 brightness selection module 310 switch module 311 light branch LI, L2, Ln resistive element 15, Rl, R2 capacitive element C diode D 13