M363548 五、新型說明: 【新型所屬之技術領域】 本創作係關於發光二極體,尤其是有關於一種以交流電驅 動之以發光二極體為光源之照明裝置。 【先前技術】 發光二極體(LED)必須以直流(DC)驅動,其所能承受 的驅動電壓僅數伏特(V)之間。所以,為應用發光二極體 ® 於採用交流(AC)驅動的日常生活的燈具時,例如AC 110V 或AC 220V,就必須透過交流直流轉換(AC-DC)電路, 而且由於發光二極體工作的特殊需求,還需要恆壓與恆流 的控制。如此,不僅增加額外空間與產品成本,而且由於 電麼轉換的彳貝耗、以及傳統AC-DC電路係屬大電流的供電 方式5這些都會造成不必要的電能損耗。 • 【新型内容】 因此,本創作提出一種以發光二極體為光源、但直接以交 流電驅動的照明裝置。本照明裝置的電路簡單、成本低廉、 穩流效果好、且不需要額外的功耗發熱元件,因此可以降 低本照明裝置的散熱需求,有效的提高了本照明裝置的可 靠性與使用壽命。 本照明裝置包含一個由四個二極體所構成的橋式整流電 路。交流電源的輸出端子之一係經過串聯之一保險絲、與 4 M363548 作為限流穩流之一第一電容,與橋式整流電路的二個輸入 端子之一連接;交流電源的另一輸出端子則直接與橋式整 流電路的另一輸入端子連接。橋式整流電路的二個輸出端 子,一方面跨接於作為穩壓濾波之一第二電容的二端,另 一方面其間則連接有多個串聯的發光二極體。這些發光二 極體係在橋式整流電路的二個輸出端子之間形成順向偏 壓,以在電流導通時發光而作為本照明裝置之光源。 ® 橋式整流電路的作用在於將交流電源輸入的正弦交流電壓 轉換為直流的漣波電壓。第二電容的作用則在將漣波電壓 加以濾波穩壓,本創作的核心係在第一電容的電容值的選 擇,其作用則在於提供簡單但極為有效之限流與穩流。 茲配合所附圖式、實施例之詳細說明及申請專利範圍,將 上述及本創作之其他目的與優點詳述於後。然而,當可了 ^ 解所附圖式純係為解說本創作之精神而設,不當視為本創 作範#之定義。有關本創作範轉之定義,請參照所附之申 請專利範圍。 【實施方式】 第1圖所示係依據本創作一實施例之照明裝置之電路示意 圖。如圖所示,本創作之照明裝置1的二線輸入端子(未 編號)係直接與一交流電源10 (例如60Hz、110V)的二 個輸出端子11、12分別連接。 5 M363548 本照明裝置1包含一個由四個二極體30所構成的橋式整流 電路。橋式整流電路的接續方式應為本創作所屬技術領域 具通常知識者所熟知,故在此不多贅述。交流電源10的輸 出端子之一(例如端子11)係經過一第一電容40,與橋式 整流電路的二個輸入端子之一(例如端子A)連接;交流 電源10的另一輸出端子(例如端子12)則直接與橋式整流 電路的另一輸入端子(例如端子B)連接。 橋式整流電路的二個輸出端子C、D,一方面跨接於一第二 電容50的二端,另一方面其間則連接有多個串聯的發光二 極體60。請注意到,這些發光二極體60必需在橋式整流電 路的二個輸出端子C、D之間形成順向偏壓,以在電流導 通時發光而作為本照明裝置之光源。 二極體30所構成的橋式整流電路的作用在於將交流電源 10輸入的正弦交流電壓轉換為直流的漣波電壓。第二電容 50的作用則在將漣波電壓加以濾波穩壓,第一電容40的作 用則在於限流與穩流。 第一電容40的電容值的選擇係本創作的核心。為計算第一 電容40,第1圖的電路可以第2圖的等效電路來模擬,其 中,具有容抗Zc的電路元件係代表第一電容40,具有阻 抗R的電路元件則係代表多個發光二極體60。以0.1W的 6 M363548 發光二極體60為例,其工作電壓約為3.0V、工作電流I 約為20mA,所以每一發光二極體60的阻抗為150Ω (3V/0.02A),假設共有18個發光二極體60,則ΪΙ=2,700Ω。 如果交流電源10是110V、60Hz,則20mA=110V/ (Zc+2,70〇n),可以推算出 Ζο=2,652Ω。因為 Zc=1/2tc/C (其 中,/是交流電壓的頻率,C是第一電容的電容質),可以 進一步推算出第一電容的電容值C應為lgF ( 2,652Ω=1/2τι·60·(:)。換言之,本照明裝置1核心元件第 > 一電容40的電容值可以根據發光二極體60的顆數、工作 電壓、工作電流、交流電源10的電壓有效值與頻率所推算 出來。和傳統的AC-DC電路比較,本照明裝置的限流機制 (第一電容40)簡單而有效。 第一電容40的另一個作用是穩流。根據發光二極體的特 性,當溫度上升時,發光二極體60的等效阻抗(例如以上 | 所計算的150Ω)降低,造成工作電流I的上升。但工作電 流I的上升會為第一電容40所吸納,使得跨越第一電容40 的電壓增加。因為交流電源10的電壓不變,第一電容40 的電壓增加,使得分壓到發光二極體60的電壓降低,因此 又將上升的工作電流I拉回,而達到穩流的效果。根據測 試,本照明裝置1從常溫上升到60°C時,工作電流I的變 化小於1mA,但在沒有第一電容40時,工作電流I將從 20mA放大一倍到40mA,這會進入一種不好的正回饋的情 形,亦即温度上升造成電流增大,而電流增大更進一步造 7 M363548 成更高的溫度,如此循環直到損壞為止。 第3圖所示係依據本創作另一實施例之照明裝置之電路示 意圖。其與第1圖所示者,差別僅在(1)交流電源10的輸 出端子之一(例如端子11)係經過串聯之一保險絲20、與 第一電容40,與橋式整流電路的二個輸入端子之一(例如 端子A)連接;(2)這些發光二極體60和橋式整流電路的 二個輸出端子C、D之間,額外串聯一個限流的電阻70。 傳統的AC-DC電路對發光二極體的供電係屬於低電壓(一 般小於24V )、低阻抗、大電流的匹配方式供電;本創作則 屬於高電壓、高阻抗、小電流的匹配方式供電。本創作與 傳統AC-DC電路的比較,如下表所示: 傳統AC-DC電路 本創作 電路型式 複雜 簡單 負載連接方式 多管並聯、或並聯 +串聯 多管串聯 悝流性能 好 好 成本 高 低 體積 中等 微小 轉換效率 80-85% 98%以上 功率因數 65 %(在無附加提升 功率因數電路時) 70% 8 M363548 散熱要求 低 尚頻電磁輕射 有 無 可靠性與使用 壽命 中等 兩 藉由以上較佳具體實施例之詳述,係希望能更加清楚描述 本創作之特徵與精神,而並非以上述所揭露的較佳具體實 施例來對本創作之範_加以限制。相反地,其目的是希望 能涵蓋各種改變及具相等性的安排於本創作所欲申請之專 利範圍的範_内。 【圖式簡單說明】 第1圖所示係依據本創作一實施例之照明裝置之電路示意 圖。 第2圖所示係模擬第1圖電路之等效電路。 第3圖所示係依據本創作另一實施例之照明裝置之電路示 意圖。 【主要元件符號說明】 1 本創作之照明裝置 10 交流電源 11 交流電源輸出端子 12 交流電源輸出端子 20 保險絲 30 二極體 40 第一電容 50 第二電容 60 發光二極體 70 電阻 M363548 A、B 橋式電路輸入端子 C、D橋式電路輸出端子 I 工作電流 Zc 容抗 R 阻抗M363548 V. New description: [New technical field] This creation is about light-emitting diodes, especially for a lighting device that uses a light-emitting diode as a light source driven by an alternating current. [Prior Art] A light-emitting diode (LED) must be driven by direct current (DC), which can withstand a driving voltage of only a few volts (V). Therefore, in order to apply LEDs to everyday lamps that use AC (AC) drive, such as AC 110V or AC 220V, AC-DC conversion circuits must be used, and LEDs work. The special needs also require constant pressure and constant current control. In this way, not only the extra space and product cost are added, but also the power consumption due to the conversion of the mussels, and the conventional AC-DC circuit is a high-current power supply mode 5, which causes unnecessary power loss. • [New content] Therefore, this creation proposes an illumination device that uses a light-emitting diode as a light source but is directly driven by an alternating current. The lighting device has the advantages of simple circuit, low cost, good steady flow effect, and no additional power consumption heating element, so the heat dissipation requirement of the lighting device can be reduced, and the reliability and service life of the lighting device are effectively improved. The lighting device comprises a bridge rectifier circuit composed of four diodes. One of the output terminals of the AC power source is connected to one of the two input terminals of the bridge rectifier circuit through one of the fuses in series, and the first capacitor of 4 M363548 as the current limiting current; the other output terminal of the AC power supply is Directly connected to the other input terminal of the bridge rectifier circuit. The two output terminals of the bridge rectifier circuit are connected on the one hand to the two ends of the second capacitor which is one of the voltage stabilization filters, and on the other hand, a plurality of LEDs connected in series are connected therebetween. These light-emitting diode systems form a forward bias between the two output terminals of the bridge rectifier circuit to emit light when the current is turned on as a light source for the illumination device. The purpose of the bridge rectifier circuit is to convert the sinusoidal AC voltage from the AC power input to the DC chopping voltage. The role of the second capacitor is to filter and regulate the chopping voltage. The core of this creation is the choice of the capacitance value of the first capacitor. Its function is to provide a simple but extremely effective current limiting and steady current. The above and other objects and advantages of the present invention will be described in detail below with reference to the drawings, the detailed description of the embodiments and the claims. However, when the understanding of the drawing is purely for the purpose of explaining the spirit of the creation, it is improperly regarded as the definition of this creation. For the definition of this creation, please refer to the attached patent application scope. [Embodiment] Fig. 1 is a circuit diagram showing a lighting device according to an embodiment of the present invention. As shown in the figure, the two-line input terminal (not numbered) of the lighting device 1 of the present invention is directly connected to two output terminals 11, 12 of an AC power source 10 (for example, 60 Hz, 110 V). 5 M363548 The lighting device 1 comprises a bridge rectifier circuit composed of four diodes 30. The connection mode of the bridge rectifier circuit should be well known to those skilled in the art, and therefore will not be described here. One of the output terminals of the AC power source 10 (for example, the terminal 11) is connected to one of the two input terminals of the bridge rectifier circuit (for example, terminal A) via a first capacitor 40; and the other output terminal of the AC power source 10 (for example) Terminal 12) is directly connected to another input terminal (eg, terminal B) of the bridge rectifier circuit. The two output terminals C, D of the bridge rectifier circuit are connected across the two ends of a second capacitor 50 on the one hand, and a plurality of LEDs 60 connected in series are connected therebetween. It is noted that these light-emitting diodes 60 must form a forward bias between the two output terminals C, D of the bridge rectifier circuit to illuminate when the current is turned on as a light source for the illumination device. The bridge rectifier circuit constituted by the diode 30 functions to convert the sinusoidal alternating current voltage input from the alternating current power source 10 into a direct current chopping voltage. The function of the second capacitor 50 is to filter and regulate the chopping voltage, and the function of the first capacitor 40 is to limit current and stabilize current. The selection of the capacitance value of the first capacitor 40 is the core of the present creation. To calculate the first capacitor 40, the circuit of FIG. 1 can be simulated by the equivalent circuit of FIG. 2, wherein the circuit component having the capacitive reactance Zc represents the first capacitor 40, and the circuit component having the impedance R represents multiple Light-emitting diode 60. Taking a 0.1W 6 M363548 light-emitting diode 60 as an example, the operating voltage is about 3.0V and the operating current I is about 20mA, so the impedance of each light-emitting diode 60 is 150Ω (3V/0.02A), assuming a total For 18 light-emitting diodes 60, ΪΙ = 2,700 Ω. If the AC power supply 10 is 110V, 60Hz, then 20mA = 110V / (Zc + 2, 70 〇 n), you can calculate Ζ ο = 2,652 Ω. Since Zc=1/2tc/C (where / is the frequency of the AC voltage and C is the capacitance of the first capacitor), it can be further inferred that the capacitance value C of the first capacitor should be lgF (2,652Ω=1/2τι· 60·(:). In other words, the core component of the illumination device 1> The capacitance value of a capacitor 40 can be based on the number of the LEDs 60, the operating voltage, the operating current, the voltage effective value of the AC power source 10, and the frequency. Inferred from the conventional AC-DC circuit, the current limiting mechanism (first capacitor 40) of the illumination device is simple and effective. The other function of the first capacitor 40 is to stabilize the flow. According to the characteristics of the light-emitting diode, when When the temperature rises, the equivalent impedance of the light-emitting diode 60 (for example, 150 Ω calculated by the above |) decreases, causing an increase in the operating current I. However, the rise of the operating current I is absorbed by the first capacitor 40, so that the first is crossed. The voltage of the capacitor 40 is increased. Since the voltage of the alternating current power source 10 is constant, the voltage of the first capacitor 40 is increased, so that the voltage divided to the light-emitting diode 60 is lowered, so that the rising operating current I is pulled back to stabilize. The effect of the flow. According to the test When the illumination device 1 rises from a normal temperature to 60 ° C, the change of the operating current I is less than 1 mA, but in the absence of the first capacitor 40, the operating current I will be doubled from 20 mA to 40 mA, which may enter a bad positive feedback. The situation, that is, the temperature rise causes the current to increase, and the current increase further makes 7 M363548 to a higher temperature, and thus cycles until it is damaged. FIG. 3 shows a lighting device according to another embodiment of the present creation. The circuit diagram is different from the one shown in FIG. 1 only in (1) one of the output terminals of the AC power source 10 (for example, the terminal 11) passes through one of the fuses 20 in series, the first capacitor 40, and the bridge rectifier circuit. One of the two input terminals (for example, terminal A) is connected; (2) between the two LEDs 60 and the two output terminals C, D of the bridge rectifier circuit, an additional current limiting resistor 70 is connected in series. The power supply of the AC-DC circuit to the LED is a low voltage (generally less than 24V), low impedance, high current matching mode power supply; this creation is a high voltage, high impedance, small current matching mode power supply. versus The comparison of the traditional AC-DC circuit is shown in the following table: Traditional AC-DC circuit The circuit type is complex and simple. The load connection method is multi-tube parallel connection, or parallel + series multi-tube series turbulence performance is good. Cost high and low volume medium and small conversion efficiency 80 -85% 98% or more power factor 65% (when there is no additional boost power factor circuit) 70% 8 M363548 Low heat dissipation requirements Long-frequency electromagnetic light shot with or without reliability and service life Two by the above detailed examples It is intended that the features and spirit of the present invention be more clearly described, and that the scope of the present invention is not limited by the preferred embodiments disclosed herein. On the contrary, it is intended to cover a variety of changes and equivalence arrangements within the scope of the patent application to which this creation is intended. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a circuit diagram showing a lighting device according to an embodiment of the present invention. Figure 2 shows the equivalent circuit of the circuit of Figure 1. Fig. 3 is a circuit diagram showing a lighting device according to another embodiment of the present creation. [Main component symbol description] 1 The lighting device of this creation 10 AC power supply 11 AC power output terminal 12 AC power output terminal 20 Fuse 30 Diode 40 First capacitor 50 Second capacitor 60 Light-emitting diode 70 Resistance M363548 A, B Bridge circuit input terminal C, D bridge circuit output terminal I operating current Zc capacitive reactance R impedance