0783 ltwf 1 .doc/006 修E曰期92.8.ί錄出· h- :0783 ltwf 1 .doc / 006 Rev. E date 92.8.ί Recorded · h-:
玖、發明說明： 本發明是有關於一種雙光源電壓調變互補控制電 路，且特別是有關於一種掃瞄器之雙光源電壓調變互補控 制電路。 知猫挤在進f了文件知猫時，是需要光源來掃瞄文件。 而掃瞄器可以做到有兩組光源來掃瞄文件，一組是背光 燈，其可以做一般文件的掃瞄；另一組是上蓋燈，其可以 掃瞄透明文件。 第1圖繪示習知掃瞄器之雙光源電路的方塊圖。在 第1圖中，特殊應用積體電路（Application Specific Integrated Circuit)102分別輸出方波信號SV1與SV2至電 壓調變電路（Voltage Modulated Circuit)104與電壓調變電 路106。其中，方波信號SV1與SV2的脈衝寬度是可以做 調整（例如從15%〜80%的範圍），當方波信號SV1與SV2 的脈衝寬度愈大時，則電壓調變電路104與電壓調變電路 106所輸出之具有直流方波電源的調變電壓MV1與MV2 之振幅就愈高。 接著，電壓調變電路104與電壓調變電路106分別 輸出調變電壓MV1與MV2至背光（Back Light)燈驅動電路 108與上蓋（Cover)燈驅動電路110，而背光燈驅動電路108 與上蓋燈驅動電路110是一組直交流變換器（Inverter*)之電 路，其可將直流電壓轉換爲交流電壓，因此背光燈驅動電 路108與上蓋燈驅動電路110分別輸出交流電源INV1與 INV2至背光燈112與上蓋燈114，使背光燈112與上蓋燈 0783ltwfl.doc/006 修正日期 92.8.2S:,、 (正 v ·' J Ή I 、· 114可以分別做文件的掃瞄，但背光燈112與上蓋燈114 是不會同時做文件掃瞄的動作。 然而，習知掃瞄器之雙光源電路是使用兩組電壓調 變電路，其使用元件的數目較多，而元件的數目增多使得 印刷電路板（Printed Circuit Board)所佔用的面積增大，相 對地使硬體的成本增加。 因此本發明係提供一種掃瞄器之雙光源電壓調變互 補控制電路，其電路僅使用一組電壓調變電路，其使用元 件的數目減少，而元件的數目減少使得印刷電路板所佔用 的面積縮小，相對地可節省硬體的成本。 本發明係提供一種掃瞄器之雙光源電壓調變互補控 制電路，其包括：一電壓調變電路，根據可調變脈波寬度 之一方波信號，以產生可調變振幅之一調變電壓；一第一 燈驅動電路，可接收調變電壓，以驅動一第一燈；一第二 燈驅動電路，可接收調變電壓，以驅動一第二燈；以及， 一互補控制電路，可根據一互補邏輯信號，以決定調變電 壓是輸出至第一燈驅動電路或第二燈驅動電路。如此之電 路結構，可節省電路的硬體成本。 爲讓本發明之上述目的、特徵、和優點能更明顯易 懂，下文特舉較佳實施例，並配合所附圖式，作詳細說明 如下： 圖式之簡單說明： 第1圖繪示習知掃瞄器之雙光源電路的方塊圖； 第2圖繪示本發明掃瞄器之雙光源電壓調變互補控 560165 0783 ltwfl.doc/006 修正曰期92.8.2^1. 年月日/ '補无 制電路的方塊圖； . 第3圖繪示電壓調變電路之一實施例的電路圖； 第4圖繪示本發明互補控制電路之一較佳實施例的 電路方塊圖； _ 第5圖繪示達靈頓電路圖；以及 - 第1表爲光源控邏輯表。 、 標號說明： 102，202 :特殊應用積體電路 104，106，204 :電壓調變電路 鲁 108，208 :背光燈驅動電路 110，210 :上蓋燈驅動電路 112，212 :背光燈 114，214 :上蓋燈 206 :互補控制電路 302 ， 304 ， 308 ， 312 ， 404 ， 406 ， 502 ， 504 ， 506 ： 電阻R - 306，310，408，410，508，510 :電晶體 _2. Description of the invention: The present invention relates to a dual light source voltage modulation complementary control circuit, and more particularly to a scanner dual light source voltage modulation complementary control circuit. Knowing the cat squeezes into the file. Knowing the cat requires a light source to scan the file. The scanner can have two sets of light sources to scan documents, one is a backlight, which can scan general documents, and the other is a cover lamp, which can scan transparent documents. Figure 1 shows a block diagram of a dual light source circuit of a conventional scanner. In FIG. 1, an application specific integrated circuit 102 outputs square wave signals SV1 and SV2 to a voltage modulating circuit 104 and a voltage modulating circuit 106, respectively. The pulse width of the square wave signals SV1 and SV2 can be adjusted (for example, from 15% to 80%). When the pulse width of the square wave signals SV1 and SV2 is larger, the voltage modulation circuit 104 and the voltage The amplitude of the modulation voltages MV1 and MV2 with a DC square wave power output from the modulation circuit 106 becomes higher. Next, the voltage modulation circuit 104 and the voltage modulation circuit 106 respectively output the modulation voltages MV1 and MV2 to the backlight light driving circuit 108 and the cover light driving circuit 110, and the backlight driving circuit 108 and The cover lamp driving circuit 110 is a group of direct AC converter (Inverter *) circuits, which can convert DC voltage to AC voltage. Therefore, the backlight driving circuit 108 and the cover lamp driving circuit 110 respectively output AC power sources INV1 and INV2 to the backlight. The lamp 112 and the cover lamp 114 make the backlight 112 and the cover lamp 0783ltwfl.doc / 006 revision date 92.8.2S: ,, (Positive v · 'J Ή I 、 · 114 can be used to scan documents, but the backlight 112 It is not possible to scan the document at the same time as the cover lamp 114. However, the dual light source circuit of the conventional scanner uses two sets of voltage modulation circuits, which use more components and increase the number of components. The printed circuit board (Printed Circuit Board) occupies an increased area, which relatively increases the cost of the hardware. Therefore, the present invention provides a dual light source voltage modulation complementary control circuit for a scanner. Using a set of voltage modulation circuits, the number of components used is reduced, and the reduced number of components reduces the area occupied by the printed circuit board, which can relatively save the cost of hardware. The present invention provides a pair of scanners The light source voltage modulation complementary control circuit includes: a voltage modulation circuit that generates a modulation voltage of one of the adjustable amplitudes according to a square wave signal of one of the adjustable pulse widths; and a first lamp driving circuit that can Receiving a modulation voltage to drive a first lamp; a second lamp driving circuit to receive a modulation voltage to drive a second lamp; and a complementary control circuit to determine modulation based on a complementary logic signal The voltage is output to the first lamp driving circuit or the second lamp driving circuit. Such a circuit structure can save the hardware cost of the circuit. In order to make the above-mentioned objects, features, and advantages of the present invention more obvious and easy to understand, the following specific examples are provided. The preferred embodiment and the accompanying drawings are described in detail as follows: Brief description of the drawings: FIG. 1 shows a block diagram of a dual light source circuit of a conventional scanner; FIG. 2 shows Invented scanner dual light source voltage modulation complementary control 560165 0783 ltwfl.doc / 006 revised date 92.8.2 ^ 1. Year / month / day / block diagram of the "unpatterned circuit"; Figure 3 shows the voltage modulation A circuit diagram of an embodiment of the circuit; FIG. 4 shows a circuit block diagram of a preferred embodiment of the complementary control circuit of the present invention; _ FIG. 5 shows a Darlington circuit diagram; and-Table 1 is a light source control logic table Description of symbols: 102, 202: Special application integrated circuits 104, 106, 204: Voltage modulation circuits Lu 108, 208: Backlight driving circuits 110, 210: Overhead lamp driving circuits 112, 212: Backlight 114, 214: Overhead lamp 206: Complementary control circuits 302, 304, 308, 312, 404, 406, 502, 504, 506: Resistance R-306, 310, 408, 410, 508, 510: Transistor _
314 :二極體D 316 :電感L . 318 :電容C 402 :共射極電路 414 ： IC ULN2003 500 :達靈頓電路 實施例 6 07831twfl.doc/006 gJE 曰·92:8：^•正 ______^懸 請參照第2圖，其繪示本發明掃瞄器之雙光源電壓 調變互補控制電路的方塊圖。在第2圖中，特殊應用積體 電路202輸出方波信號SV至電壓調變電路204，同樣地， 方波信號SV的脈衝寬度是可以做調整，當方波信號sv 的脈衝寬度愈大時，則電壓調變電路204所輸出之具有直 流電壓的調變電壓MV就愈高。而且，特殊應用積體電路 202輸出互補邏輯信號F/U LAMP至互補控制電路 206(Reciprocal Control Circuit)，以決定電壓調變電路 204 所輸出之調變電壓MV是輸出至背光燈驅動電路208或是 上蓋燈驅動電路210。 接著，電壓調變電路204輸出調變電壓MV至互補 控制電路206後，互補控制電路206根據特殊應用積體電 路202所輸出的互補邏輯信號F/U LAMP，再將調變電壓 MV供應背光燈驅動電路108或上蓋燈驅動電路110。而 背光燈驅動電路208與上蓋燈驅動電路210同樣是一組直 交流變換器之電路，其可將直流電壓轉換爲交流電壓，因 此背光燈驅動電路208與上蓋燈驅動電路210分別輸出交 流電源INV1與INV2至背光燈212與上蓋燈214，使背光 燈212與上蓋燈214可以分別做文件的掃瞄，但背光燈212 與上蓋燈214是不會同時做文件掃瞄的動作。 第3圖繪示電壓調變電路之一實施例的電路圖。在 第3圖中，電阻R 302的第一端接收特殊應用積體電路 2〇2(參考第2圖）所輸出的方波信號SV，電阻R 304的第 一端耦接至電阻R 302的第二端，電阻R 304的第二端接 丨修氐曰期92.8.2亡314: Diode D 316: Inductance L. 318: Capacitor C 402: Common emitter circuit 414: IC ULN2003 500: Darlington Circuit Example 6 07831twfl.doc / 006 gJE: 92: 8: ^ • Positive_ _____ ^ Please refer to FIG. 2, which illustrates a block diagram of a dual light source voltage modulation complementary control circuit of the scanner of the present invention. In Figure 2, the special application integrated circuit 202 outputs a square wave signal SV to the voltage modulation circuit 204. Similarly, the pulse width of the square wave signal SV can be adjusted. When the square wave signal sv has a larger pulse width, At this time, the modulation voltage MV with a DC voltage output by the voltage modulation circuit 204 is higher. Moreover, the special application integrated circuit 202 outputs a complementary logic signal F / U LAMP to a complementary control circuit 206 (Reciprocal Control Circuit) to determine whether the modulation voltage MV output by the voltage modulation circuit 204 is output to the backlight driving circuit 208 Or the cover lamp driving circuit 210. After the voltage modulation circuit 204 outputs the modulation voltage MV to the complementary control circuit 206, the complementary control circuit 206 supplies the modulation voltage MV to the backlight according to the complementary logic signal F / U LAMP output by the special application integrated circuit 202. The lamp driving circuit 108 or the cover lamp driving circuit 110. The backlight driving circuit 208 and the cover lamp driving circuit 210 are also a set of DC-AC converter circuits, which can convert DC voltage to AC voltage. Therefore, the backlight driving circuit 208 and the cover lamp driving circuit 210 output AC power INV1 respectively. And INV2 to the backlight 212 and the cover lamp 214, so that the backlight 212 and the cover lamp 214 can scan documents, respectively, but the backlight 212 and the cover lamp 214 do not scan the document at the same time. FIG. 3 is a circuit diagram of an embodiment of a voltage modulation circuit. In Fig. 3, the first terminal of the resistor R 302 receives the square wave signal SV output by the special application integrated circuit 202 (refer to Fig. 2), and the first terminal of the resistor R 304 is coupled to the resistor R 302. The second terminal, the second terminal of the resistor R 304, the repair period is 92.8.2.
0783 ltwf 1 .doc/006 地。電阻R 308的第一端耦接至12V的電壓源，電阻R 312 的第一端耦接至電阻R 308的第二端。電晶體306的電源 端耦接至電阻R 312的第二端，電晶體306的控制端耦接 至電阻R 302的第二端，電晶體306的負載端接地。電晶 體310的電源端耦接至12V的電壓源，電晶體310的控制 端耦接至電阻R 308的第二端。二極體D 314的陰極耦接 至電晶體310的負載端，二極體D 314的陽極接地。電感 L 316的第一端耦接至電晶體310的負載端，電感L 316 的第二端爲輸出調變電壓MV的輸出端。電容C 318的第 一端耦接至電感L 316的第一端，電容C 318的第二端接 在第3圖中，電阻R 302、304、308、312與電晶體 330、310所組成之電路部分，其是做爲升壓控制，而電阻 R 302、304、308、312的電阻値皆不相同，電感L 316與 電容C 318是做爲儲能之用，二極體D 314是做爲電流迴 路之用。 互補控制電路206(參考第2圖）係由-共射極電路與 一達靈頓電路組成，如第4圖繪示本發明互補控制電路之 一較佳實施例的電路方塊圖所示。在第4圖中，共射極電 路（Common Emitter Circuit)402 是由電阻 R 404、406 與電 晶體408與410所組成的。電阻R 404的第一端接收特殊 應用積體電路202所輸出的互補邏輯信號F/U LAMP，電 阻R 406的第一端耦接至5V的電壓源，電晶體408的電 源端耦接至電阻R 406的第二端，電晶體408的控制端耦 07831twfl.doc/006 修正日期92.8.21 Λ- V L; 接至電阻R 404的第二端，電晶體408的負載端接地，電 晶體410的電源端耦接至上蓋燈驅動電路210的接地端 ULAMP_GND，電晶體410的控制端耦接至電阻R 406的 第二端，電晶體410的負載端接地。其中，共射極電路4〇2 中的電晶體410是設計爲汲取（Sink)較大的電流，所以選 用電晶體410的電流規格要注意。 IC ULN2003 414的輸入端IB、2B並聯後接收特殊 應用積體電路202所輸出的互補邏輯信號F/U LAMP，1C ULN2003 414的輸出端1C、2C並聯後耦接至背光燈驅動 電路 208 的接地端 FLAMP_GND，IC ULN2003 414 的 E 端接地，IC ULN2003 414的COM端耦接至12V的電壓源。 互補控制電路206接收特殊應用積體電路202所輸出的調 變電壓MV後，並分別輸出此調變電壓MV至上蓋燈驅動 電路210的電源端ULAMP_POEWER與背光燈驅動電路 208的電源端FLAMP_POWER。其中，電阻R 404、406 的電阻値是不相同的，而IC ULN2003 414爲達靈頓電路 的1C，其具有七組達靈頓電路，IC ULN2003 414的輸入 端IB ' 2B、3B、4B、5B、6B、7B分別是七組達靈頓電 路的輸入端，而IC ULN2003 414的輸出端1C、2C、3C、 4C、5C、6C、7C分別是七組達靈頓電路的輸出端。 第5圖繪示達靈頓電路圖。在達靈頓電路(Darlington αιχιπ〇500中的電阻R 502的第一端接收特殊應用積體電 路202所輸出的互補邏輯信號F/U LAMP，電阻R 504的 第一端耦接至電阻502的第二端，電阻R 506的第一端耦 560165 07831twfl.doc/006 修正日期 92.8.2g, 接至電阻R 504的第二端，電阻R 506的第二端接地。電 晶體508的電源端耦接至背光燈驅動電路208(參考第4圖） 的接地端FLAMP_GND，電晶體508的控制端耦接至電阻 R 502的第二端，電晶體508的負載端耦接至電阻R 504 的第二端，電晶體510的電源端耦接至背光燈驅動電路 208(參考第4圖）的接地端FLAMP_GND，電晶體510的控 制端耦接至該電阻R 504的第二端，電晶體510的負載端 接地。而電阻R 502、504、506的電阻値皆不相同。 第1表爲光源控邏輯表，並參照第4圖與第5圖之 電路圖。當特殊應用積體電路202(參考第2圖）所輸出的 互補邏輯信號F/U LAMP爲HIGH及脈波寬度調變之方波 信號SV爲PULSE/HIGH時，則電晶體408爲”ON”狀態， 如此電晶體410爲”OFF”狀態，使得上蓋燈驅動電路210 的電源端ULAMP_POWER與接地端ULAMP_GND形成開 路，而上蓋燈214(參考第2圖）是”OFF”的狀態。同樣地， 當特殊應用積體電路202(參考第2圖）所輸出的互補邏輯 信號F/U LAMP爲HIGH及脈波寬度調變之方波信號SV 爲PULSE/HIGH時，則電晶體508與電晶體510同時爲”ON” 狀態，使得背光燈驅動電路208的電源端FLAMP_POWER 與接地端FLAMP_GND形成通路，背光燈驅動電路208接 收具有直流電壓之調變電壓MV，而使背光燈212(參考第 2圖）是在”ON”的狀態。 同理，當特殊應用積體電路202(參考第2圖）所輸出 的互補邏輯信號F/U LAMP爲LOW及脈波寬度調變之方 10 i i560165 07831twfl.doc/006 修正日期 92 冬·28 波信號SV爲PULSE/HIGH時，則電晶體408爲”OFF”狀 態，如此電晶體410爲”ON”狀態，使得上蓋燈驅動電路210 的電源端ULAMP_POWER與接地端ULAMP_GND形成通 路，上蓋燈驅動電路210接收具有直流電壓之調變電壓 MV，而使上蓋燈214(參考第2圖）是在”ON”的狀態。同樣 地，當特殊應用積體電路202(參考第2圖）所輸出的互補 邏輯信號F/U LAMP爲LOW及脈波寬度調變之方波信號 SV爲PULSE/HIGH時，則電晶體508與電晶體510同時 爲”OFF”狀態，使得背光燈驅動電路208的電源端 FLAMP_POWER與接地端FLAMP_GND形成開路，而背 光燈212(參考第2圖）是”OFF”的狀態。 在第1表中，雙光源電壓調變互補控制電路是可以 操作省電模式，乃由特殊應用積體電路202(參考第2圖) 輸出脈波寬度調變之方波信號SV爲LOW，此時，無論特 殊應用積體電路202(參考第2圖）所輸出的互補邏輯信號 F/U LAMP是在何種狀態，此LOW之電壓都不足以使背 光燈212(參考第2圖）或上蓋燈214(參考第2圖）在”〇N”的 狀態。 綜上所述，當互補控制電路接收特殊應用積體電路 所輸出的互補邏輯信號時，互補控制電路所輸出的互補邏 輯信號，在同一個時間只會使背光燈與上蓋燈的其中一個 是在”ON”的狀態。如此，只需要一組電壓調變電路就可以 提供背光燈與上蓋燈所需的電源。在第4圖中所使用的1C ULN2003 414，其就是掃瞄器內原有的構件，不需要再增 11 560165 07831twfl.d〇c/〇〇6 修吾曰其,92.8.28 ! · 加額外的1C。再者，共射極電路402與第3圖之電壓調變 電路相比較，共射極電路402的電路架構是很簡單，而且 電路構件很少，所以不會佔用印刷電路板很大的面積。 因此，本發明的優點係僅使用一組電壓調變電路， 其使用元件的數目減少，而元件的數目減少使得印刷電路 板所佔用的面積縮小，相對地可節省硬體的成本。 綜上所述，雖然本發明已以較佳實施例揭露如上， 然其並非用以限定本發明，任何熟習此技藝者，在不脫離 本發明之精神和範_內，當可作各種之更動與潤飾，因此 本發明之保護範圍當視後附之申請專利範圍所界定者爲 準。 120783 ltwf 1 .doc / 006 land. The first terminal of the resistor R 308 is coupled to a 12V voltage source, and the first terminal of the resistor R 312 is coupled to the second terminal of the resistor R 308. The power terminal of the transistor 306 is coupled to the second terminal of the resistor R 312, the control terminal of the transistor 306 is coupled to the second terminal of the resistor R 302, and the load terminal of the transistor 306 is grounded. The power supply terminal of the transistor 310 is coupled to a 12V voltage source, and the control terminal of the transistor 310 is coupled to the second terminal of the resistor R 308. The cathode of the diode D 314 is coupled to the load terminal of the transistor 310, and the anode of the diode D 314 is grounded. The first terminal of the inductor L 316 is coupled to the load terminal of the transistor 310, and the second terminal of the inductor L 316 is an output terminal for outputting the modulation voltage MV. The first terminal of the capacitor C 318 is coupled to the first terminal of the inductor L 316. The second terminal of the capacitor C 318 is connected to the third figure. The resistor R 302, 304, 308, 312 and the transistor 330, 310 are combined. The circuit part is used for boost control, and the resistances of resistors R 302, 304, 308, and 312 are all different. The inductor L 316 and capacitor C 318 are used for energy storage, and the diode D 314 is used for For the current loop. The complementary control circuit 206 (refer to Fig. 2) is composed of a -emitter circuit and a Darlington circuit, as shown in Fig. 4 which shows a circuit block diagram of a preferred embodiment of the complementary control circuit of the present invention. In Figure 4, the common emitter circuit (Common Emitter Circuit) 402 is composed of resistors R 404, 406 and transistors 408 and 410. The first terminal of the resistor R 404 receives the complementary logic signal F / U LAMP output by the special application integrated circuit 202. The first terminal of the resistor R 406 is coupled to a 5V voltage source, and the power terminal of the transistor 408 is coupled to the resistor. The second terminal of R 406, the control terminal of transistor 408 is coupled to 07831twfl.doc / 006 Amendment date 92.8.21 Λ-VL; Connect to the second terminal of resistor R 404, the load terminal of transistor 408 is grounded, and the transistor 410 The power terminal is coupled to the ground terminal ULAMP_GND of the cover lamp driving circuit 210, the control terminal of the transistor 410 is coupled to the second terminal of the resistor R 406, and the load terminal of the transistor 410 is grounded. Among them, the transistor 410 in the common emitter circuit 402 is designed to sink a large current, so the current specifications of the transistor 410 should be paid attention to. The input terminals IB and 2B of IC ULN2003 414 are connected in parallel to receive the complementary logic signal F / U LAMP output by the special application integrated circuit 202. The output terminals 1C and 2C of ULC2003 414 are coupled to the ground of the backlight driving circuit 208 after being connected in parallel. Terminal FLAMP_GND, the E terminal of IC ULN2003 414 is grounded, and the COM terminal of IC ULN2003 414 is coupled to a 12V voltage source. The complementary control circuit 206 receives the modulation voltage MV output from the special application integrated circuit 202, and outputs the modulation voltage MV to the power supply terminal ULAMP_POEWER of the cover lamp driving circuit 210 and the power supply terminal FLAMP_POWER of the backlight driving circuit 208, respectively. Among them, the resistance 値 of the resistors R 404 and 406 are different, and IC ULN2003 414 is 1C of the Darlington circuit, which has seven groups of Darlington circuits, and the input terminals IB ′ 2B, 3B, 4B of IC ULN2003 414, 5B, 6B, and 7B are the input terminals of seven groups of Darlington circuits, and the output terminals of IC ULN2003 414 are 1C, 2C, 3C, 4C, 5C, 6C, and 7C are the output terminals of seven groups of Darlington circuits. Figure 5 shows the Darlington circuit diagram. The first terminal of the resistor R 502 in the Darlington circuit 500 receives a complementary logic signal F / U LAMP output by the special application integrated circuit 202, and the first terminal of the resistor R 504 is coupled to the resistor 502. The second terminal, the first terminal of the resistor R 506 is coupled to 560165 07831twfl.doc / 006, the date of correction is 92.8.2g, connected to the second terminal of the resistor R 504, and the second terminal of the resistor R 506 is grounded. The power terminal of the transistor 508 is coupled Connected to the ground terminal FLAMP_GND of the backlight driving circuit 208 (refer to FIG. 4), the control terminal of the transistor 508 is coupled to the second terminal of the resistor R 502, and the load terminal of the transistor 508 is coupled to the second terminal of the resistor R 504 Terminal, the power terminal of the transistor 510 is coupled to the ground terminal FLAMP_GND of the backlight driving circuit 208 (refer to FIG. 4), the control terminal of the transistor 510 is coupled to the second terminal of the resistor R 504, and the load of the transistor 510 The terminal R is grounded. The resistances of resistors R 502, 504, and 506 are all different. The first table is the light source control logic table, and refer to the circuit diagrams in Figures 4 and 5. When the special application integrated circuit 202 (refer to Figure 2) (Figure) The complementary logic signal F / U LAMP output is HIGH and the pulse width is adjusted. When the square wave signal SV is PULSE / HIGH, the transistor 408 is in the "ON" state, so that the transistor 410 is in the "OFF" state, so that the power supply terminal ULAMP_POWER and the ground terminal ULAMP_GND of the cover lamp driving circuit 210 are open, and the cover The light 214 (refer to FIG. 2) is “OFF”. Similarly, when the complementary logic signal F / U LAMP output by the special application integrated circuit 202 (refer to FIG. 2) is HIGH and the pulse width is adjusted, When the square wave signal SV is PULSE / HIGH, the transistor 508 and the transistor 510 are simultaneously “ON”, so that the power supply terminal FLAMP_POWER and the ground terminal FLAMP_GND of the backlight driving circuit 208 form a path. The backlight driving circuit 208 receives The voltage MV is adjusted so that the backlight 212 (refer to FIG. 2) is in the “ON” state. Similarly, when the special application integrated circuit 202 (refer to FIG. 2) outputs the complementary logic signal F / U LAMP is the formula of LOW and pulse width modulation. 10 i i560165 07831twfl.doc / 006 Correction date 92 Winter. 28 When the wave signal SV is PULSE / HIGH, the transistor 408 is “OFF”, so the transistor 410 is "ON" state, so that Cap lamp driving circuit 210 power terminal ULAMP_POWER and the ground terminal ULAMP_GND formed passage, cover a lamp driving circuit 210 receives the modulated voltage MV a DC voltage, the upper cap lamp 214 (see Fig. 2) is in the "ON" state. Similarly, when the complementary logic signal F / U LAMP output by the special application integrated circuit 202 (refer to FIG. 2) is LOW and the square wave signal SV of the pulse width modulation is PULSE / HIGH, the transistor 508 and The transistor 510 is in the "OFF" state at the same time, so that the power supply terminal FLAMP_POWER and the ground terminal FLAMP_GND of the backlight driving circuit 208 form an open circuit, and the backlight 212 (refer to Fig. 2) is in the "OFF" state. In the first table, the dual light source voltage modulation complementary control circuit can operate in the power saving mode, and the special application integrated circuit 202 (refer to FIG. 2) outputs the square wave signal SV of the pulse width modulation to LOW. At this time, regardless of the state of the complementary logic signal F / U LAMP output by the special application integrated circuit 202 (refer to FIG. 2), the voltage of this LOW is not enough to make the backlight 212 (refer to FIG. 2) or the cover. The lamp 214 (refer to FIG. 2) is in a state of "ON". In summary, when the complementary control circuit receives the complementary logic signal output by the special application integrated circuit, the complementary logic signal output by the complementary control circuit will only make one of the backlight and the cover light at the same time. "ON" status. In this way, only one set of voltage modulation circuit is needed to provide the power required for the backlight and the cover lamp. The 1C ULN2003 414 used in Figure 4, which is the original component in the scanner, does not need to be added 11 560165 07831twfl.d〇c / 〇〇6 Xiu Wu Yue Qi, 92.8.28! · Add extra 1C. In addition, compared with the voltage modulation circuit of FIG. 3, the common emitter circuit 402 has a simple circuit structure and few circuit components, so it does not occupy a large area of the printed circuit board. . Therefore, the advantage of the present invention is that only one set of voltage modulation circuits is used, the number of components used is reduced, and the reduced number of components reduces the area occupied by the printed circuit board, which can relatively save the cost of hardware. In summary, although the present invention has been disclosed in the preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Retouching, so the scope of protection of the present invention shall be determined by the scope of the attached patent application. 12