201122334 六、發明說明： 【發明所屬之技術領域】 本發明係有關一種LED燈泡’特別是關於一種LED 聚光燈泡。 【先前技術】 燈泡依用途可分為照明用燈泡及裝飾用燈泡。聚光燈 泡是一種裝飾用燈泡，與照明用燈泡提供寬廣且均勻的光 • 照射不同，聚光燈泡刻意將光線集中在狹小的區域中。目 前的聚光燈泡多採用函素杯燈，雖具有便宜、高亮度及柔 和色溫的優點，卻有高耗電量、高溫及短壽命的缺點。 發光二極體（Light Emitting Diode; LED)應用在燈泡 上，在耗電量及壽命上皆優於傳統的燈泡，但有商品化的 困難。使用直流電LED在燈泡上，必須增加電源轉換器將 交流電轉換成直流電供應給直流電LED，因此會增加燈泡 φ 的成本，而且電源轉換器很難完全藏放在標準燈頭内，因 此需要額外的機構件容納電源轉換器，造成成本及體積皆 增加。改用交流電LED作為光源可以省去電源轉換器，因 此能降低成本及體積，然而在高功率應用上，卻需要體積 龐大的散熱器，造成成本及體積皆增加。圖1所示係一種 已經商品化的LED聚光燈泡，為了幫助LED 10散熱，在 反射杯12外增加散熱器14，LED 10安裝在高導熱的燈座 16上’燈座16連接散熱器丨4，因此從LED 10經燈座16 到散熱器14形成良好的散熱途徑。散熱器14的體積通常 201122334 是燈頭18的數倍大，因此這種燈泡的體積比傳統的燈泡大 很多。散熱器14讓燈泡的結構變複雜，不但需要增加接合 散熱器14與燈頭18的機構件，也造成組裝的困難。為了 配合不同口徑或形狀的反射杯12，散熱器14的形狀和尺 寸也必須跟著改變，導致成本增加，生產管理的難度也提 高。 【發明内容】 本發明的目的之一，在於提出一種LED聚光燈泡，尤 指高功率的LED聚光燈泡。 根據本發明，一種LED聚光燈泡包含具有第一及第二 電極的燈頭，電路板電連接至該第一電極，功率在0.5瓦 以上的交流電LED安裝在該電路板上，電阻值介於50至 50000歐姆之間的電阻器電連接在該電路板和第二電極之 間，因而與該交流電LED串聯在該第一及第二電極之間構 成一個迴路，導熱係數介於0.25至30W/mK之間的導熱絕 緣材料充填在該第一電極的内部，因而機械性接觸該電路 板及第一電極，提供熱通道幫助該交流電LED散熱至該第 一電極，以及聚光罩固定在該電路板上，該聚光罩的底部 具有孔洞露出該交流電LED，該聚光罩的内表面上具有反 射面反射該交流電LED的光線。 【實施方式】 圖2係根據本發明的LED聚光燈泡，LED 10採用功 201122334 率在〇.5瓦(W)以上的交流電LED，且安裝在標準燈頭20 上’聚光罩22也固定在標準燈頭20上。交流電LED已經 有成熟的商品可以採用，LED 10可以選擇使用電壓為20 至340伏特之間的產品，顏色為白光、暖白光或其他顏色。 使用標準燈頭20是為了可以取代傳統的聚光燈泡。所謂標 準燈頭’係指目前已經標準化，可以直接插入通用燈座的 燈頭’例如鎢絲燈泡所用的E20、E22、E17、E36、E27， 或_素燈泡所用的MR38及GU10等等。圖2中的標準燈 ^ 頭20係鎢絲燈泡所用的燈頭，其具有彼此絕緣的第一電極 24與第二電極26，且第一電極24係圓柱狀且有螺紋的金 屬殼。在此實施例中，聚光罩22的底部伸出具有彈性的腳 28 ’可以直接插在標準燈頭2〇上。在其他實施例中，可以 改用膠合或螺合將聚光罩22固定在標準燈頭20上。 圖3係聚光罩22的立體視圖以及上、下視圖，其係在 底部具有孔洞30的塑膠殼體上塗佈高反射率薄膜或鍍上 # 尚反射率金屬（例如鋁或鋁合金）形成反射面32。 參照圖4的剖視圖，在標準燈頭2〇内，電路板34藉 焊錫焊接至第一電極24，電阻值介於50至50000歐姆之 間的電阻器36電連接在電路板34和第二電極26之間，以 及導熱係數介於0.25至30W/mK之間的導熱絕緣材料38 充填在第一電極24的内部。[ED 10焊接在電路板34上， 因而與電阻器36串聯在第一電極24及第二電極26之間構 成一個迴路。聚光罩22的腳28插在電路板34上，因而將 聚光罩22固定在電路板34上，也讓LED 1〇在聚光2 [S] 5 201122334 的孔洞30中，因此LED 10的光線被聚光罩22的反射面 32反射而形成平行的光束。導熱絕緣材料38機械性接觸 電路板34及第一電極24，提供熱通道幫助LED 10散熱至 第一電極24，從其發散至周圍環境。因為第一電極24是 大面積的金屬殼，其上更具有螺紋，所以可以很有效地幫 助LED 10散熱。導熱絕緣材料38同時也包住電阻器36， 因而也可以幫助電阻器36散熱至第一電極24。 通常在1W以上的LED稱為高功率LED，由於本發明 不需要散熱器，因此即使在高功率應用上，LED聚光燈泡 需要的體積也很小，可以小於傳統的燈泡。聚光罩20的口 徑和反射面32的形狀可以依照需求設計，不會影響到其他 零組件，因此只需要準備一種燈頭即可。因為使用交流電 LED 10，因此LED聚光燈泡可直接插入一般燈泡插座， 不必更換燈具或加裝轉接器。 【圖式簡單說明】 圖1係習知的LED聚光燈泡； 圖2係根據本發明的LED聚光燈泡； 圖3係圖2中的聚光罩的立體視圖；以及 圖4係圖2中的LED聚光燈泡的剖視圖。 【主要元件符號說明】 10 交流電LED 12 反射杯 201122334 14 散熱器 16 燈座 18 燈頭 20 標準燈頭 22 聚光罩 24 第一電極 26 第二電極 28 腳 30 孔洞 32 反射面 34 電路板 36 電阻器 38 散熱絕緣材料201122334 VI. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to an LED bulb, particularly to an LED spotlight bulb. [Prior Art] Light bulbs can be classified into lighting bulbs and decorative bulbs depending on the application. Spotlights A decorative light bulb that provides a broad and uniform light to the lighting bulb. The spotlight bulb deliberately concentrates light in a small area. The current spotlight bulbs are mostly made of a letter cup lamp. Although they have the advantages of low cost, high brightness, softness and color temperature, they have the disadvantages of high power consumption, high temperature and short life. Light Emitting Diode (LED) is applied to the bulb, which is superior to the conventional bulb in terms of power consumption and life, but it is difficult to commercialize. When using a DC LED on the bulb, the power converter must be added to convert the AC power to DC power to the DC LED, thus increasing the cost of the bulb φ, and the power converter is difficult to completely hide in the standard lamp cap, so additional mechanical components are required. The power converter is accommodated, resulting in an increase in cost and volume. Switching to an AC LED as a light source eliminates the need for a power converter, thereby reducing cost and size. However, in high-power applications, a bulky heat sink is required, resulting in increased cost and size. Figure 1 shows a commercially available LED spotlight bulb. To help dissipate the heat of the LED 10, a heat sink 14 is added outside the reflector cup 12. The LED 10 is mounted on a lamp holder 16 of high thermal conductivity. Therefore, a good heat dissipation path is formed from the LED 10 through the socket 16 to the heat sink 14. The volume of the heat sink 14 is usually several times that of the lamp cap 18, so the volume of the bulb is much larger than that of the conventional bulb. The heat sink 14 complicates the structure of the bulb, and it is not only necessary to increase the mechanical components that engage the radiator 14 and the base 18, but also causes difficulty in assembly. In order to match the reflector cups 12 of different calibers or shapes, the shape and size of the radiator 14 must also be changed, resulting in an increase in cost and difficulty in production management. SUMMARY OF THE INVENTION One object of the present invention is to provide an LED concentrating light bulb, especially a high power LED concentrating light bulb. According to the present invention, an LED concentrating light bulb includes a lamp cap having first and second electrodes, the circuit board is electrically connected to the first electrode, and an alternating current LED having a power of 0.5 watt or more is mounted on the circuit board, and the resistance value is between 50 and A resistor between 50000 ohms is electrically connected between the circuit board and the second electrode, and thus a circuit is formed in series with the alternating current LED between the first and second electrodes, and the thermal conductivity is between 0.25 and 30 W/mK. a thermally conductive insulating material is filled inside the first electrode, thereby mechanically contacting the circuit board and the first electrode, providing a heat channel to help the AC LED to dissipate heat to the first electrode, and the concentrating cover is fixed on the circuit board The bottom of the concentrating cover has a hole to expose the alternating current LED, and the inner surface of the concentrating cover has a reflecting surface reflecting the light of the alternating current LED. [Embodiment] FIG. 2 is an LED concentrating light bulb according to the present invention. The LED 10 is an AC LED having a power of 201122334 at a rate of 〇5 watts (W) or more, and is mounted on the standard base 20. The concentrating cover 22 is also fixed in the standard. On the lamp cap 20. Alternating current LEDs are available in mature products. LED 10 can be used with products ranging from 20 to 340 volts in white, warm white or other colors. The standard base 20 is used in order to replace the conventional spotlight bulb. The so-called standard lamp head refers to the lamp head that has been standardized and can be directly inserted into a common lamp holder, such as E20, E22, E17, E36, E27 used for tungsten light bulbs, MR38 and GU10 used for _ prime bulbs, and the like. The standard lamp of Fig. 2 is a lamp head for a tungsten filament bulb having a first electrode 24 and a second electrode 26 insulated from each other, and the first electrode 24 is a cylindrical and threaded metal shell. In this embodiment, the bottom of the concentrating mask 22 projecting from the resilient foot 28' can be inserted directly into the standard base 2'. In other embodiments, the concentrating shield 22 can be secured to the standard base 20 by gluing or screwing. 3 is a perspective view and upper and lower views of the concentrating cover 22, which are coated with a high reflectivity film or a plated reflective metal (for example, aluminum or aluminum alloy) on a plastic case having a hole 30 at the bottom. Reflecting surface 32. Referring to the cross-sectional view of FIG. 4, in the standard lamp head 2, the circuit board 34 is soldered to the first electrode 24, and the resistor 36 having a resistance value between 50 and 50,000 ohms is electrically connected to the circuit board 34 and the second electrode 26. A thermally conductive insulating material 38 is interposed between the first electrode 24 and a thermal conductive material 38 having a thermal conductivity of between 0.25 and 30 W/mK. [ED 10 is soldered to the circuit board 34, thus forming a loop between the first electrode 24 and the second electrode 26 in series with the resistor 36. The legs 28 of the concentrating cover 22 are inserted on the circuit board 34, thereby fixing the concentrating cover 22 to the circuit board 34, and also illuminating the LED 1 in the hole 30 of the concentrating 2 [S] 5 201122334, thus the LED 10 The light is reflected by the reflecting surface 32 of the concentrating mask 22 to form a parallel beam. The thermally conductive insulating material 38 mechanically contacts the circuit board 34 and the first electrode 24, providing a thermal path to help the LED 10 dissipate heat to the first electrode 24, from which it diverges to the surrounding environment. Since the first electrode 24 is a large-area metal case which is more threaded thereon, the heat dissipation of the LED 10 can be effectively assisted. The thermally conductive insulating material 38 also encases the resistor 36, thus also helping the resistor 36 to dissipate heat to the first electrode 24. LEDs typically above 1 W are referred to as high power LEDs. Since the present invention does not require a heat sink, even in high power applications, LED spotlight bulbs require a small volume that can be smaller than conventional bulbs. The aperture of the concentrating cover 20 and the shape of the reflecting surface 32 can be designed according to requirements without affecting other components, so only one type of lamp base needs to be prepared. Because the AC LED 10 is used, the LED spotlight bulb can be plugged directly into a typical bulb socket without having to replace the fixture or retrofit the adapter. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conventional LED concentrating light bulb; FIG. 2 is an LED concentrating light bulb according to the present invention; FIG. 3 is a perspective view of the concentrating cover of FIG. 2; and FIG. 4 is an LED of FIG. A cross-sectional view of a spotlight bulb. [Main component symbol description] 10 AC LED 12 Reflector cup 201122334 14 Heatsink 16 Lamp holder 18 Lamp cap 20 Standard lamp cap 22 Condenser 24 First electrode 26 Second electrode 28 Foot 30 Hole 32 Reflecting surface 34 Circuit board 36 Resistor 38 Thermal insulation material