1335716 六 [0001] 099年07月08日修正替换頁I發明說明： 【發明所屬之技術領域】 本發明係關於一種電源電路。 [0002] [0003] [0004] 【先前技術】 電源電路被廣泛用於各種電器之電路中，為不同電路提 供工作電源。 清參閱圖1，其係一種先前技術電源電路之電路結構示意 圖。該電源電路100包括一第一整流濾波電路u、一保護 電路13、一變壓器15、一第二整流濾波電路1 6、一脈寬 調變晶片17、一整流二極體18及一電晶體19。該第一整 流遽波電路11包括一全橋整流電’路Π 0，一濾.波電容114 、二輸入端111、112及一輸出端113 ’該變壓器15包括 一初級繞組151、一輔助繞組152及一次級繞組153，該 第一整流濾波電路16包括二輸入端161、162及一輸出端 163 ’該脈寬調變晶片17包括一電壓輸入端171及一控制 端 172« 其中，該全橋整流電路110之二輸入端即該第一整流濾波 電路11之二輸入端111、112，該全橋整流電路110之正 輸出端即該第一整流濾波電路Π之輸出端113，該全橋整 流電路110之負輸出端接地，該濾波電容n4並聯於該全 橋整流電路110之正輸出端與負輸出端之間。該初級繞組 151與該保護電路13並聯，該初級繞組151之一端電連接 於該第一整流濾波電路丨丨之輸出端113，另一端電連接於 該電晶體19之汲極，依次經由該電晶體丨9之源極及一源 極電阻1 90接地’該電晶體〗9之閘極與該脈寬調變晶片j 7 096111569 表單編號A0101 第4頁/共20頁 0993243612-0 099年07月08日修正替換頁 1335716 之控制端172電連接。該輔助繞組152之一端依次經由該 整流二極體18之陽極、陰極與該脈寬調變晶片17之電壓 輸入端171電連接，另一端接地。該次級繞組153之二端 分別與該第二整流濾波電路16之二輸入端161、162電連 接。 [0005] 外部交流電壓輸入至該第一整流濾波電路11之二輸入端 111、112，藉由該第一整流濾波電路11整流、濾波後輸 出為直流電壓，並提供給該初級繞組151。該輔助繞組 152感應該初級繞組151並藉由該整流二極體18為該脈寬 調變晶片17提供其所需之直流工作電壓，該脈寬調變晶 片17發出脈衝訊號以控制該.電晶體開關，從而控制 該變壓器15之工作。當該電晶:體J9掌it時，該濾波電容 114、該初級繞組151與該電晶體19構成一迴路；當該電 晶體19截止時，該次級繞組153釋放其所感應並儲存之電 能，經由該第二整流濾波電路16整流、濾波後輸出穩定 之直流電壓，該初級繞組151所產生之勵磁電流藉由該保 護電路13消耗掉。 [0006] 惟，該電源電路100中採用電晶體19作為開關元件，由於 電晶體19一般成本較高，不利該電源電路100之低成本化 。而且，該電源電路之脈衝訊號藉由該脈寬調變晶片17 產生，脈寬調變晶片17成本較高，亦造成該電源電路100 成本較高。 【發明内容】 [0007] 有鑑於此，有必要提供一種成本較低之電源電路。 [0008] 一種電源電路，其包括一整流濾波電路、一變壓器、一 096111569 表單編號 A0101 第 5 頁/共 20 頁 0993243612-0 1335716 099年07月08日後正替换頁 第一電晶體、一脈衝產生電路及一輸出電路，該變壓器 包括一初級繞組、一輔助繞組及一次級繞組，該第一電 晶體係雙極性接面，在該第一電晶體之控制下，外界交 流電經過該整流渡波電路、該變壓及該輸出電路後輸 出直流電壓，該脈衝產生電路接收該輔助繞組之感應電 壓而產生一電壓脈衝訊號，並將該電壓脈衝訊號傳輸至 該第一電晶體之基極以控制該第一電晶體之導通及截止 ，該電源電路，進一步包括一過流保護電路，該過流保 護電路採樣該第一電晶體之射極電流，並輸出一電壓訊 號至該第一電晶體基極。 [0009] 一種電源電路，其包括一整流‘渡波電路、一變壓器、一 第一電晶體、一脈衝產生電路及一輸出電路，該變壓器 包括一初級繞組、一輔助繞組及一次級繞組，該第一電 晶體係雙極性接面電晶體，在該第一電晶體之控制下， 外界交流電經過該整流濾波電路、該變壓器及該輸出電 路後輸出直流電壓，該脈衝產生電路接收該輔助繞組之 感應電壓而產生一電壓脈衝訊號，並將該電壓脈衝訊號 傳輸至該第一電晶體之基極以控制該第一電晶體之導通 及截止，該電源電路進一步包括一尖峰吸收電路，該尖 峰吸收電路並聯於該初級繞組兩端。 [0010] 一種電源電路，其包括一整流濾波電路、一變壓器、一 第一電晶體、一脈衝產生電路及一輪出電路，該變壓器 包括一初級繞組、一輔助繞組及一次級繞組，該第一電 晶體係雙極性接面電晶體，在該第一電晶體之控制下， 外界交流電經過該整流濾波電路、該變壓器及該輸出電 096111569 表單編號A0101 第6頁/共20頁 0993243612-0 1335716 099年07月08曰 修正 路後輸出直流電壓’該脈衝產生電路接收該輔助繞組之 感應電壓而產生一電壓脈衝訊號，並將該電壓脈衝訊號 傳輪至該第一電晶體之基極以控制該第一電晶體之導通 及戴止，該脈衝產生電路包括一第三電阻、一第四電容 、一第三二極體、一第三電容及一穩壓二極體，該第三 電阻一端電連接該第一電晶體之基極，另一端與該第四 電容串聯，該第三電容一端接地，另一端與該第三二極 體之正極串聯，該第四電容另一端及該第三二極體之負 極均電連接至該輔助繞組之同一端，該輔助繞組另一端 接地’該穩壓二極體正極與該第三二極體正極相連，負 極電連接至該第一電晶體之基極^ .'id 乂+: ，、-:乂逢·.; 勹::’: [0011] 相較於先前技術’該電源電路之:，開<先_華一電晶體採 用較為便宜之雙極性接面，有利於節約^本；同時，藉 由該輔助繞阻及脈衝產生電路產生脈衝控制訊號，所需 元件少’使採用該電源電路之電子產品體積小，成本低 ’滿足目前小型電子產品價格低廉之需求。 【實施方式】 [0012]請參閱圖2，其係本發明電源電路之電路結構示意圖。該 電源電路200包括二電源輸入端210、211、一整流渡波 電路220、一尖峰吸收電路230、一變壓器240、一脈衝 產生電路250 ' —第一電晶體260、一啟動電阻261、一 過流保護電路270、一輸出電路280及一輸出端290。 [0013] 該整流遽波電路220包括一第一二極體221、一第一電容 222及一第一電阻223，該第一電容222為電解質電容。 該變壓器240包括一初級繞組241 ' —輔助繞組242及一 096111569 表單煸號A0101 第7頁/共20頁 0993243612-0 13357161335716 VI [0001] Corrective replacement page I of July 08, 2008. Description of the Invention: [Technical Field of the Invention] The present invention relates to a power supply circuit. [0003] [Prior Art] Power supply circuits are widely used in circuits of various electric appliances to provide operating power for different circuits. Referring to Figure 1, there is shown a circuit diagram of a prior art power supply circuit. The power circuit 100 includes a first rectifying and filtering circuit u, a protection circuit 13, a transformer 15, a second rectifying and filtering circuit 16, a pulse width modulation chip 17, a rectifying diode 18, and a transistor 19. . The first rectifying chopper circuit 11 includes a full bridge rectification circuit Π 0, a filter wave capacitor 114, two input terminals 111, 112 and an output terminal 113. The transformer 15 includes a primary winding 151 and an auxiliary winding. 152 and the primary winding 153, the first rectifying and filtering circuit 16 includes two input ends 161, 162 and an output end 163'. The pulse width modulation chip 17 includes a voltage input end 171 and a control end 172«. The two input ends of the bridge rectifier circuit 110 are the two input ends 111, 112 of the first rectifying and filtering circuit 11, and the positive output end of the full bridge rectifying circuit 110 is the output end 113 of the first rectifying and filtering circuit ,, the full bridge The negative output terminal of the rectifier circuit 110 is grounded, and the filter capacitor n4 is connected in parallel between the positive output terminal and the negative output terminal of the full bridge rectifier circuit 110. The primary winding 151 is connected in parallel with the protection circuit 13. One end of the primary winding 151 is electrically connected to the output end 113 of the first rectifying and filtering circuit 丨丨, and the other end is electrically connected to the drain of the transistor 19, and sequentially via the electric The source of the crystal 丨9 and a source resistor 1 90 are grounded. The gate of the transistor -9 and the pulse width modulation chip j 7 096111569 Form No. A0101 Page 4 / Total 20 pages 0993243612-0 099 July On the 08th, the control terminal 172 of the replacement page 1335716 is electrically connected. One end of the auxiliary winding 152 is electrically connected to the voltage input terminal 171 of the pulse width modulation chip 17 via the anode and cathode of the rectifying diode 18 in sequence, and the other end is grounded. The two ends of the secondary winding 153 are electrically connected to the two input terminals 161, 162 of the second rectifying and filtering circuit 16, respectively. The external AC voltage is input to the two input terminals 111 and 112 of the first rectifying and filtering circuit 11, and is rectified and filtered by the first rectifying and filtering circuit 11 to be output as a DC voltage, and is supplied to the primary winding 151. The auxiliary winding 152 senses the primary winding 151 and provides the pulse width modulation chip 17 with the required DC operating voltage by the rectifying diode 18, and the pulse width modulation chip 17 sends a pulse signal to control the electricity. The crystal switch controls the operation of the transformer 15. When the transistor: body J9 is it, the filter capacitor 114, the primary winding 151 and the transistor 19 form a loop; when the transistor 19 is turned off, the secondary winding 153 releases the energy that is induced and stored. After being rectified and filtered by the second rectifying and filtering circuit 16, a stable DC voltage is output, and the exciting current generated by the primary winding 151 is consumed by the protection circuit 13. [0006] However, the power supply circuit 100 employs the transistor 19 as a switching element. Since the transistor 19 is generally costly, the cost of the power supply circuit 100 is disadvantageous. Moreover, the pulse signal of the power circuit is generated by the pulse width modulation chip 17, and the pulse width modulation chip 17 has a high cost, which also causes the power circuit 100 to have a high cost. SUMMARY OF THE INVENTION [0007] In view of the above, it is necessary to provide a lower cost power supply circuit. [0008] A power supply circuit comprising a rectifying and filtering circuit, a transformer, a 096111569, a form number A0101, a fifth page, a total of 20, 0993243612-0, 1335716, after the reversal of the first transistor, a pulse generation a circuit and an output circuit, the transformer includes a primary winding, an auxiliary winding and a primary winding, the first electro-crystalline system has a bipolar junction, and under the control of the first transistor, the external alternating current passes through the rectification wave circuit, The voltage conversion and the output circuit output a DC voltage, the pulse generating circuit receives the induced voltage of the auxiliary winding to generate a voltage pulse signal, and transmits the voltage pulse signal to the base of the first transistor to control the first The power circuit further includes an overcurrent protection circuit that samples an emitter current of the first transistor and outputs a voltage signal to the first transistor base. [0009] A power supply circuit includes a rectifying wave circuit, a transformer, a first transistor, a pulse generating circuit, and an output circuit, the transformer including a primary winding, an auxiliary winding, and a primary winding, the first An electro-ceramic system bipolar junction transistor, under the control of the first transistor, the external alternating current outputs a DC voltage through the rectification filter circuit, the transformer and the output circuit, and the pulse generation circuit receives the induction of the auxiliary winding Generating a voltage pulse signal and transmitting the voltage pulse signal to a base of the first transistor to control conduction and deactivation of the first transistor, the power circuit further comprising a spike absorption circuit, the peak absorption circuit Parallel to both ends of the primary winding. [0010] A power supply circuit includes a rectifying and filtering circuit, a transformer, a first transistor, a pulse generating circuit, and a wheel-out circuit, the transformer including a primary winding, an auxiliary winding, and a primary winding, the first The electro-crystal system bipolar junction transistor, under the control of the first transistor, the external alternating current passes through the rectification filter circuit, the transformer and the output power 096111569 Form No. A0101 Page 6 / 20 pages 0993243612-0 1335716 099 The system generates a DC voltage after the correction of the road. The pulse generating circuit receives the induced voltage of the auxiliary winding to generate a voltage pulse signal, and transmits the voltage pulse signal to the base of the first transistor to control the The first transistor is turned on and off. The pulse generating circuit includes a third resistor, a fourth capacitor, a third diode, a third capacitor, and a voltage stabilizing diode. Connecting the base of the first transistor, the other end is connected in series with the fourth capacitor, the third capacitor is grounded at one end, and the other end is connected in series with the anode of the third diode. The other end of the fourth capacitor and the negative electrode of the third diode are electrically connected to the same end of the auxiliary winding, and the other end of the auxiliary winding is grounded. The positive electrode of the steady voltage diode is connected to the positive pole of the third diode, and the negative pole is electrically connected. Connected to the base of the first transistor ^ .'id 乂+: , , -:乂逢·.; 勹::': [0011] Compared to the prior art 'the power circuit:, open < _Huayi crystal adopts cheaper bipolar junction, which is beneficial to save the cost. At the same time, the auxiliary winding and pulse generating circuit generates pulse control signals, and the required components are few 'electronic products using the power circuit. Small size and low cost' meet the current low price requirements for small electronic products. [Embodiment] [0012] Please refer to FIG. 2, which is a schematic diagram of a circuit structure of a power supply circuit of the present invention. The power circuit 200 includes two power input terminals 210, 211, a rectification wave circuit 220, a peak absorbing circuit 230, a transformer 240, a pulse generating circuit 250' - a first transistor 260, a starting resistor 261, and an overcurrent The protection circuit 270, an output circuit 280 and an output terminal 290. The rectifier chopper circuit 220 includes a first diode 221, a first capacitor 222, and a first resistor 223. The first capacitor 222 is an electrolyte capacitor. The transformer 240 includes a primary winding 241' - an auxiliary winding 242 and a 096111569. Form number A0101 Page 7 of 20 0993243612-0 1335716
099年〇7月〇8日修正替換頁I 次級繞組243。該過流保護電路270包括一第二電晶體 271、一第四二極體272及一採樣電阻273。其中，該第 —電晶體260及該第二電晶體271均為雙極性接面 (Bipolar Junction Transistor, BJT)，其均包括 —射極e、一基極b及一集極c β ⑽14] 該整流濾波電路2 2 0之二輸入端即為該二電源輸入端21 〇 、211，該電源輸入端210正向串聯該第一二極體221， 然後依次經過該變壓器240之初級繞組241及該第一電晶 體260並藉由該採樣電阻273接地’其中該第一電晶體 260之集極c與該初級繞組241相連，射極e與該採樣電阻 273相連。該電源輸入端211經由該第一電阻223接地。 該第一電容222正極電連接該第一二極賤221-之負極，負 極接地，該第一電容222與該第一二極體221之節點為該 整流渡波電路220之輸出端（未標不）。該啟動電阻261電 連接於該整流瀘、波電路220之輸出端及該第一電晶體26〇 之基極b之間。 [0015] 該第二電晶體271之集極c與該第一電晶體26〇之基極b相 連，射極e接地，基極b反向串聯該第四二極體272後經該 採樣電阻273接地。 [0016] 該尖峰吸收電路230包括一第二二極體231、一第二電容 232及一第二電阻233。該第二電容232與該第二電阻233 拉聯後與該第二二極體231串聯。該尖峰吸收電路23〇做 為一支路並聯於該初級繞組241兩端。 [0017] 該脈衝產生電路250包括一第三二極體25i、一第三電容 096111569 表單編號A0101 第8頁/共20頁 0993243612-0 1335716 [0020] 096111569 099年07月08日修正 252、一第三電阻253 ' —穩壓二極體254及一第四電容 255 ’其中該第三電容252亦為電解質電容。該第三電阻 253一端與該第四電容255串聯後經由該輔助繞組242接 地’另一端電連接於該第一電晶體26〇之基極。該第三二 極體251之負極電連接至該第四電容255與該輔助繞組 242之連接點’正極電連接至該第三電容252之負極，該 第三電容252之正極接地。該穩壓二極體254之穩壓值為 6.2V，其正極與該第三電容252之負極相連，負極電連接 至該第一電晶體260之基極b。 [0018] 該輸出電路280實質上為一整流濾波電路，其包括一第五 二極體281及一第五電容282.，典中該第釜電:容282為極 性電容。該次級繞組243—端.正向·串聯該第五二極體281 後電連接至該輸出端290 ’另一端接地。該第五電容282 正極接該第五二極體281之負極，負極接地。 [0019] 該電源電路200之工作原理描述如下： 初始狀態時，該第一電晶體260截止，該電源電路2〇〇内 部無電流及電壓。當接通電源時，由該二電源輸入端210 、211輪入交流電進入該整流濾波電路22〇，經該第一二 極體221半波整流及該第一電容222濾波後輸出穩定直流 電壓，其中，該第一電阻223具有限流作用，防止輸入電 流過大。該直流電壓分別經過該啟動電阻261及該初級繞 組241後加載於該第一電晶體260之基極b及集極c，根據 雙極性接面特性，此時該第一電晶體260之基極b形成基 極電流，基極電流Ibi經過該第一電晶體260放大後形 成集極-射極電流icei，該第一電晶體26〇導通，輸入電 表單編St A0101 第 9 頁/共 20 頁 0993243612-0 1335716 丨 099年 07了 流依次經過該初級繞組241 '第一電晶體260及該採樣電 阻273後入地構成迴路。由於該初級繞組241之電磁感應 作用，在電磁感應飽和以前，該初級繞組241内之電流線 性增加。 [0021] 當該初級繞組241内有持續變化之電流時，該輔助繞組 242由電磁感應產生感應電壓，該輔助繞組242與該初級 繞組241正激’由於該輔助繞組242—端直接接地，該輔 助繞組242與該第三二極體251連接一端為負電壓，該負 電壓經過該第三二極體251整流及該第三電容252濾波後 輸出穩定負電壓，該負電壓加載於該穩壓二極體254之正 極，當該第一電晶體260之基極b與該穩壓二極體254正極 之間之電壓達到該穩壓二極.體254之k穿電壓時，該穩壓 二極體254反向導通，從而將該第一電晶體260之基極b電 壓拉低至負電壓，使該第一電晶體260截止，基極電流Correction replacement page I secondary winding 243 in 099 〇 July 〇 8th. The overcurrent protection circuit 270 includes a second transistor 271, a fourth diode 272, and a sampling resistor 273. The first transistor 260 and the second transistor 271 are both Bipolar Junction Transistors (BJTs), each of which includes an emitter e, a base b, and a collector c β (10) 14] The input end of the rectifying and filtering circuit 2 2 0 is the two power input terminals 21 〇, 211, and the power input terminal 210 is forwardly connected in series with the first diode 221, and then sequentially passes through the primary winding 241 of the transformer 240 and the The first transistor 260 is grounded by the sampling resistor 273. The collector c of the first transistor 260 is connected to the primary winding 241, and the emitter e is connected to the sampling resistor 273. The power input terminal 211 is grounded via the first resistor 223. The first capacitor 222 is electrically connected to the anode of the first diode 221-, and the cathode is grounded. The node of the first capacitor 222 and the first diode 221 is the output of the rectifier circuit 220 (not labeled ). The starting resistor 261 is electrically connected between the output of the rectifying 泸, the wave circuit 220 and the base b of the first transistor 26A. [0015] The collector c of the second transistor 271 is connected to the base b of the first transistor 26, the emitter e is grounded, and the base b is reversely connected in series with the fourth diode 272. 273 is grounded. [0016] The peak absorbing circuit 230 includes a second diode 231, a second capacitor 232, and a second resistor 233. The second capacitor 232 is connected to the second resistor 231 and connected in series with the second diode 231. The peak absorbing circuit 23 is connected in parallel as a branch to both ends of the primary winding 241. [0017] The pulse generating circuit 250 includes a third diode 25i and a third capacitor 096111569. Form No. A0101 Page 8 / Total 20 pages 0993243612-0 1335716 [0020] 096111569 Correction 252, July 10, 2008 The third resistor 253 ′ is a voltage stabilizing diode 254 and a fourth capacitor 255 ′, wherein the third capacitor 252 is also an electrolytic capacitor. One end of the third resistor 253 is connected in series with the fourth capacitor 255, and is electrically connected to the base of the first transistor 26 through the auxiliary winding 242. The cathode of the third capacitor 251 is electrically connected to the cathode of the fourth capacitor 255 and the auxiliary winding 242, and is electrically connected to the cathode of the third capacitor 252. The anode of the third capacitor 252 is grounded. The voltage regulator diode 254 has a regulation voltage of 6.2V, its anode is connected to the cathode of the third capacitor 252, and the cathode is electrically connected to the base b of the first transistor 260. [0018] The output circuit 280 is substantially a rectifying and filtering circuit, and includes a fifth diode 281 and a fifth capacitor 282. The first capacitor: 282 is a capacitive capacitor. The secondary winding 243 is terminated. The fifth diode 281 is forwardly connected in series and electrically connected to the other end of the output terminal 290'. The fifth capacitor 282 is connected to the cathode of the fifth diode 281, and the cathode is grounded. [0019] The working principle of the power supply circuit 200 is described as follows: In the initial state, the first transistor 260 is turned off, and the power circuit 2 has no current and voltage inside. When the power is turned on, the two power input terminals 210 and 211 turn the alternating current into the rectifying and filtering circuit 22, and the first diode 221 is half-wave rectified and the first capacitor 222 filters to output a stable DC voltage. The first resistor 223 has a current limiting function to prevent the input current from being excessive. The DC voltage is applied to the base b and the collector c of the first transistor 260 after passing through the starting resistor 261 and the primary winding 241, respectively. According to the characteristics of the bipolar junction, the base of the first transistor 260 is at this time. b forms a base current, and the base current Ibi is amplified by the first transistor 260 to form a collector-emitter current icei, and the first transistor 26 is turned on, and the input current form is St A0101, page 9 of 20 0993243612-0 1335716 丨099 07 The flow passes through the primary winding 241 'the first transistor 260 and the sampling resistor 273 and then enters the ground to form a loop. Due to the electromagnetic induction of the primary winding 241, the current in the primary winding 241 increases linearly before the electromagnetic induction is saturated. [0021] When there is a continuously varying current in the primary winding 241, the auxiliary winding 242 generates an induced voltage by electromagnetic induction, and the auxiliary winding 242 is positively excited with the primary winding 241. Since the auxiliary winding 242 is directly grounded, the The auxiliary winding 242 is connected to the third diode 251 with a negative voltage. The negative voltage is rectified by the third diode 251 and filtered by the third capacitor 252 to output a stable negative voltage. The negative voltage is applied to the voltage regulator. The positive electrode of the diode 254, when the voltage between the base b of the first transistor 260 and the positive terminal of the voltage regulator diode 254 reaches the voltage of the voltage regulator diode 254, the voltage regulator The polar body 254 is reverse-conducted, thereby pulling the base b voltage of the first transistor 260 to a negative voltage, causing the first transistor 260 to be turned off, and the base current
Ibi為零，相應該第一電晶體260放大流I ,為零，該初 cel 級繞組241處於截止狀態。 [0022] 當該初級繞組241處於截止狀態時，該輔助繞組242不產 生電磁感應，無電壓，該輔助繞組242相當於導線，則該 第四電容255相當於直接接地，該第三電阻253通過該啟 動電阻261電連接至該第一電容222之正極，此時電源通 過該啟動電阻261及該第三電阻253向該第四電容255充 電’該第四電容255之電壓持續上升，導致該第一電晶體 260之基極b電壓升高，當該基極b電壓達到該第一電晶體 260之啟動電壓時，該第一電晶體26〇再次導通，該初級 繞組241再次產生持續變化之電流β 096111569 表單編號Α0101 第10頁/共20頁 0993243612-0 1335716 [0023] 099年07月〇8日 該次級繞組243與該初級繞組241反激連接，當該第一電 晶體260導通時，該初級繞組241内產生變化之電流，該 次級繞組243產生感應電動勢，此時該第五二極體281反 激截止’電能儲存於該次級繞組243上；當該第一電晶體 260截止時’該次級繞組243感應電壓反向，該第五二極 體281正激導通’該次級繞組243之電能經由該第五二極 體281整流及該第五電容282濾波後由該輸出端290輸出 [0024] 上述過程為該電源電路200之一工作週期，此週期不斷重 複，使該輸出端290輸出穩定直流電壓。 [0025] 由於當該第一電晶體260由$通到截止瞬間""電流產生突變 ，該初級繞組241二端產生鱗鈿嵩電壓，、稱爲尖峰電壓， 該尖峰電壓可能損壞該第一電晶體260造成電路失效。故 於該初級繞組241兩端並聯該尖峰吸收電路230後，尖峰 電壓藉由該第二二極體231向該第二電容232充電及通過 該第二電阻233放電以消耗該尖峰電壓，避免尖峰電壓損 壞電路。 [0026] 在該第一電晶體260導通時，電流流過該採樣電阻273， 該採樣電阻273之採樣電壓藉由該第五二極體281加載於 該第二電晶體271之基極b。在電路正常工作情況下，該 採樣電阻273之採樣電壓小於該第二電晶體271之開啟電 壓，如果由於短路或過載而導致該初級繞組241内流過超 額大電流時，該採樣電壓隨電流增大而增大，當該採樣 電壓大於該第二電晶體271之基極b開啟電壓時，形成基 極電流Ib2 ’該基極電流經由該第二電晶體271放大形 096111569 表單编號 A0101 第 11 頁/共 20 頁 0993243612-0 丄幻5716 成集極-射極電流Ice2，該集極—射極電流與該第一 電晶體260之基極電流Ibi疊加共同流過該啟動電阻261， 該啟動電阻261上分壓增大，使該第一電晶體26〇基極b之 電壓降低，當降低至不能滿足該第一電晶體260之開啟電 壓需要時，該第一電晶體260截止，該初級繞組241中電 流截止，實現該電源電路2〇〇之過流保護功能。 [0027] 相較於先前技術，該電源電路2〇〇之開關元件第一電晶體 260採用較為便宜之雙極性接面，有利於節約成本；同時 ’該脈衝產生電路250通過該變壓器240之輔助繞組242 及周邊基本電子元件來實現，代替較為昂貴之脈衝產生 晶片，可進一部節約成本另#，該電源電路2〇〇包括— 過流保護電路270 ’防止該電源電。路2〇〇在負載過大或短 路情況下造成電源損壞或引發危險，具有更高之可靠性 及安全性。 [0028] 综上所述，本發明確已符合發明專利之要件，爰依法提 出申請專利。惟，以上所述者僅係本發明之較佳實施方 式，本發明之範圍並不以上述實施方式爲限，舉凡熟習 本案技藝之人士援依本發明之精神所作之等效修飾或變 化，皆應涵蓋於以下申請專利範圍内。 【圖式簡單說明】 [0029] [0030] [0031] 099年 07^08 日 圖1係一種先前技術電源電路之電路結構示意圖。. 圖2係本發明電源電路之電路結構示意圖。 【主要元件符號說明】 電源電路：200 096111569 表單編號Α0101 第丨2頁/共20頁 0993243612-0 1335716 099年07月08日接正替换頁 [0032] 電源輸入端：21 0、211 [0033] 整流濾波電路：220 [0034] 第一二極體：221 [0035] 第一電容：222 [0036] 第一電阻：2 2 3 [0037] 尖峰吸收電路：230 [0038] 第二二極體：231 [0039] 第二電容：232 [0040] 第二電阻：233 、 " [0041] '. -* * . ·'·?.· Γ'.»-...· .二.-，- 變壓器：240 [0042] 初級繞組：241 [0043] 輔助繞組：242 [0044] 次級繞組：2 4 3 [0045] « 脈衝產生電路：250 [0046] 第三二極體：251 [0047] 第三電容：252 [0048] 第三電阻：253 [0049] 穩壓二極體：254 [0050] 第四電容：255 096111569 表單編號A0101 第13頁/共20頁 0993243612-0 1335716 099年07月08日隹正替换頁 [0051] 第一電晶體：260 [0052] 啟動電阻：2 61 [0053] 過流保護電路：270 [0054] 第二電晶體：271 [0055] 第四二極體：272 [0056] 採樣電阻：273 [0057] 輸出電路：2 8 0 [0058] 第五二極體：281 [0059] 第五電容：282 [0060] 輸出端：290 0993243612-0 096111569 表單編號A0101 第14頁/共20頁Ibi is zero, corresponding to the first transistor 260 amplifying the stream I, zero, and the initial cel-level winding 241 is in an off state. [0022] When the primary winding 241 is in an off state, the auxiliary winding 242 does not generate electromagnetic induction, no voltage, the auxiliary winding 242 is equivalent to a wire, then the fourth capacitor 255 is equivalent to direct grounding, and the third resistor 253 passes The starting resistor 261 is electrically connected to the anode of the first capacitor 222. At this time, the power source charges the fourth capacitor 255 through the starting resistor 261 and the third resistor 253. The voltage of the fourth capacitor 255 continues to rise, resulting in the first The voltage of the base b of a transistor 260 rises. When the voltage of the base b reaches the starting voltage of the first transistor 260, the first transistor 26 turns on again, and the primary winding 241 again generates a continuously changing current. β 096111569 Form No. 1010101 Page 10/Total 20 Page 0993243612-0 1335716 [0023] The secondary winding 243 is back-connected to the primary winding 241 on July 8th, 2008, when the first transistor 260 is turned on, A varying current is generated in the primary winding 241, and the secondary winding 243 generates an induced electromotive force. At this time, the fifth diode 281 is reverse-powered and stored in the secondary winding 243; when the first transistor 260 At the end of time, the secondary winding 243 induces a voltage reversal, and the fifth diode 281 is positively conducting. The electric energy of the secondary winding 243 is rectified by the fifth diode 281 and filtered by the fifth capacitor 282. The output terminal 290 outputs [0024] The above process is a duty cycle of the power supply circuit 200, and the cycle is repeated, so that the output terminal 290 outputs a stable DC voltage. [0025] Since the first transistor 260 is mutated from the current to the cut-off instant "" current, the primary winding 241 generates a scale voltage, called a spike voltage, which may damage the first A transistor 260 causes a circuit failure. Therefore, after the peak absorbing circuit 230 is connected in parallel across the primary winding 241, the peak voltage is charged to the second capacitor 232 by the second diode 231 and discharged through the second resistor 233 to consume the peak voltage to avoid spikes. Voltage damage circuit. When the first transistor 260 is turned on, current flows through the sampling resistor 273, and the sampling voltage of the sampling resistor 273 is applied to the base b of the second transistor 271 by the fifth diode 281. In the normal operation of the circuit, the sampling voltage of the sampling resistor 273 is smaller than the opening voltage of the second transistor 271. If an excessive excess current flows in the primary winding 241 due to a short circuit or an overload, the sampling voltage increases with the current. Large and increasing, when the sampling voltage is greater than the base b opening voltage of the second transistor 271, the base current Ib2' is formed. The base current is amplified by the second transistor 271. 096111569 Form No. A0101 No. 11 Page / Total 20 pages 0993243612-0 丄幻5716 is a collector-emitter current Ice2, the collector-emitter current and the base current Ibi of the first transistor 260 are superimposed and flow through the starting resistor 261, the start The voltage division on the resistor 261 is increased to lower the voltage of the base electrode b of the first transistor 26, and the first transistor 260 is turned off when the voltage of the first transistor 260 is lowered. The current in the winding 241 is cut off, and the overcurrent protection function of the power circuit 2 is realized. [0027] Compared with the prior art, the switching element first transistor 260 of the power circuit 2 采用 adopts a cheaper bipolar junction, which is advantageous for cost saving; and the pulse generating circuit 250 is assisted by the transformer 240. Winding 242 and peripheral basic electronic components are implemented instead of the more expensive pulse generating wafers, which can be further cost-effective. The power supply circuit 2 includes an overcurrent protection circuit 270' to prevent the power supply. Road 2〇〇 causes power supply damage or danger in the event of excessive or short load, and has higher reliability and safety. [0028] In summary, the present invention has indeed met the requirements of the invention patent, and the patent application is filed according to law. However, the above-mentioned embodiments are merely preferred embodiments of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and those skilled in the art will be able to make equivalent modifications or variations in accordance with the spirit of the present invention. It should be covered by the following patent application. BRIEF DESCRIPTION OF THE DRAWINGS [0030] [0031] FIG. 1 is a schematic diagram of a circuit structure of a prior art power supply circuit. Fig. 2 is a schematic view showing the circuit structure of the power supply circuit of the present invention. [Main component symbol description] Power supply circuit: 200 096111569 Form number Α 0101 Page 2 / Total 20 pages 0993243612-0 1335716 099 July 8th replacement page [0032] Power input: 21 0, 211 [0033] Rectifier filter circuit: 220 [0034] First diode: 221 [0035] First capacitor: 222 [0036] First resistor: 2 2 3 [0037] Peak absorbing circuit: 230 [0038] Second diode: 231 [0039] Second capacitance: 232 [0040] Second resistance: 233, " [0041] '. -* * . · '·?.· Γ'.»-...·. II.-,- Transformer: 240 [0042] Primary winding: 241 [0043] Auxiliary winding: 242 [0044] Secondary winding: 2 4 3 [0045] « Pulse generating circuit: 250 [0046] Third diode: 251 [0047] Three capacitors: 252 [0048] Third resistor: 253 [0049] Regulator diode: 254 [0050] Fourth capacitor: 255 096111569 Form number A0101 Page 13 / Total 20 pages 0993243612-0 1335716 099 July 08 Sundial Replacement Page [0051] First Transistor: 260 [0052] Startup Resistor: 2 61 [0053] Overcurrent Protection Circuit: 270 [0054] Second Transistor: 271 [0055] Fourth Dipole :272 [0056] Sampling resistance: 273 [0057] Output circuit: 2 8 0 [0058] Fifth diode: 281 [0059] Fifth capacitor: 282 [0060] Output: 290 0993243612-0 096111569 Form number A0101 Page 14 of 20