546883 A7 B7- 五、發明説明（1 技街範_ 本發明一般係屬於用戶線路介面電路及較特別者係屬於 此種電路中用於線路驅動器過電流保護之安排。 發明背景 在一用戶線路介面電路（SL 1C)中之驅動器利用其自己之 輸出端連接至一二線路輸送線路之各自之線路上及利用其 自己之輸入端來加上具有諸如線路電流，通話信號，振鈴 信號，等之橫向電流來傳送至輸送線路内。 縱向電流如感應電流經常在輸送線路上出現。此種在輸 送線路上之縱向電流可在SLIC中測得，且在SLIC中提供有 用於產生與一測得之縱向電流成比例之電流供應至線路驅 動器之輸入端來抵消該縱向電流之裝置。 在一例如當輸送線路之二線路之一接地成短路時之事故 情況之事件中，高縱向電流出現。此種高縱向電流在SLIC 中可抵消至一限制之值，但如與供應連接至線路驅動器之 振鈴電流高橫向電流相加時，此種高縱向電流由於在線路 驅動器内產生之電能為一高值之事實將破壞該線路驅動器 〇 發明概要 發明之目的為當一事故情形發生時來減低由線路驅動器 所驅動之電流全部之量。 按照發明目的之達成當縱向電流超過一門檻值時將橫向 電流減低或甚至加以阻絕。 因而，不致有對線路驅動器由於高電流所造成之過電量 -4- 本紙張尺度適用中國國家標準(CNS) A4規格(210X297公釐)546883 A7 B7- V. Description of the invention (1 Technical Street Fan _ This invention generally belongs to the subscriber line interface circuit and more specifically belongs to this circuit for the arrangement of line driver overcurrent protection. BACKGROUND OF THE INVENTION A subscriber line interface The driver in the circuit (SL 1C) uses its own output terminal to connect to the respective line of the one or two line transmission line and uses its own input terminal to add a horizontal signal with line current, call signal, ring signal, etc. Current is transmitted to the transmission line. Vertical currents such as induced currents often appear on the transmission line. Such vertical currents on the transmission line can be measured in SLIC, and SLIC provides a means for generating a measured vertical A device in which a proportional current is supplied to the input of the line driver to counteract the longitudinal current. In the event of an accident such as when one of the two lines of the transmission line is shorted to ground, a high longitudinal current occurs. Longitudinal current can be offset to a limited value in SLIC, but if the ringing current connected to the supply to the line driver is high When the currents are added, such a high longitudinal current will destroy the line driver due to the fact that the electric energy generated in the line driver is a high value. SUMMARY OF THE INVENTION The purpose of the invention is to reduce the power driven by the line driver when an accident occurs. The total amount of current. According to the purpose of the invention, when the vertical current exceeds a threshold value, the horizontal current is reduced or even blocked. Therefore, there will be no over-charge caused by the high current of the line driver. -4- This paper is applicable to China National Standard (CNS) A4 specification (210X297 mm)
而遭受損害之危險。 圖式簡單娓明 發明將利用參考以下所附之圖1詳細予以說明之，圖1 中為SL1 c利用按照發明之一用於過電流保護之安排之具 體實施例之原理顯示圖。 發明說明 圖1為一 SLIC 1利用按照發明之一用於預防過電流來保 護SLIC之安排之一具體實施例之原理顯示圖。 按已知之方式，sue 1包含將其自己之輸入端連接至一 可控制電流衰減器6之各自之輸出端及利用其自己之輸出 端連接至各自之一二線路輪送線路A，B至一用戶站8之二線 路驅動器2, 3。 電流衰減器6之輸入端供應有一例如線路電流，通話信號 ，振鈴k號，等之橫向電流丨况，由於線路驅動器2, 3來傳遞 至輸送線路A，B内送至用戶站8。 並且，按已知之方式，SLic丨包含用於偵測及抵消在輸 送線路A，B上任何縱向電流之裝置。 在圖1所示之具體實施例中，線路驅動器2,3為電流放大 者。 為偵測一縱向電流採對線路八，8加以測定，且藉例如差動 放大器方式利用電壓至電流轉，器91〇之裝置與一參考值 加以比較來達成。 電壓至電流轉器9利用一輸入端連接至輸送線路之線路a 且利用其另一輸入端連接至參考電壓^。正常時，參考電 本纸银尺度適用中國國家標準(CNS) A4規格(210X297公釐) 546883 A7 ____- B7 五、發明説明（3 ) 壓VI等於接地。轉換器9將接地與線路a之電位間之電位差 轉換至一為供應至一電流放大器4之一第一輸入端之電流 17 〇 電壓至電流轉換器10利用一輸入端連接至輸送線路之線 路B且其另一輪入連接至參考電壓V2。正常時，參考電壓V2 相對於VI而言為一負電位，轉換器1〇將採V2與線路b之電位 間之電位差轉換為一供應至電流放大器4之一第二輸入端 之電流18。 電流放大器4具有二個輸出端連接至各自之線路驅動器 2, 3之輸入端。電流放大器適合於輸出各自之與電流17與μ 間之差相符之為比例於在輸送線路上線路驅動器2, 3以外 之縱向電流之輸出電流15, 16。電流15, 16被送至線路驅動 器2, 3來抵消在線路A及B上之縱向電流。 如線路驅動器2, 3被替代為電壓放大者時，在線路a及線 路B中之電流將加以測定以便決定一任何縱向電流之值。 根據本發明，提供一電流放大器4，具有一第三輸出端， 用來輸出對應於電流放大器4輸出至線路驅動器2, 3之電流 15, 16之一電流14，以抵消線路A與B上之縱向電流。 電流放大器4之第三輸出端連接至一電流比較器5之一第 一輸入端。電流比較器5之一第二輸入端連接至一產生一參 考電流19之參考電流產生器7。色考電流19設計成與一縱向 電流相一致且為一較指定之保証之由SL 1C所供應之最大縱 向電流為稱高之電流。如此，SLIC能抵消較參考電流19相 一致之縱向電流為稍高之電流。故電流14必需永遠能較參 -6- 本紙張尺度適用中國國家標準(CNS) A4規格(210X297公釐） 546883 A7 B7 五、發明説明（4 ) 考電流19大方可。 電流比較器5利用其輸出端連接至電流衰減器6之一控制 輸入端。 在其輸出端，電流比較器5當14> 19時產生一輸出電流13 。當在輸送線路上之縱向電流為甚高之值時電流13控制電 流衰減器6來增加其衰減量來降低甚至阻絕橫向電流I n。 藉此由減低橫向電流使損害驅動器之危險予以減低。 按此一舉例，在正常情況，SL 1C可保証抵消達到20毫安 之縱向電流。在此情形，14> 19。在事故情況，縱向電流為 >20毫安。為了偵測事故情況，參考電流19最好是設定為縱 向電流之任意值20毫安相一致及一與由線路驅動器2, 3能 驅動之最大縱向電流如24毫安之電流值。19可設定與如22 毫安相一致。當14> 19時然後一事故情況被測得。當電流14 對應於一縱向電流>22 mA時，電流比較器5會偵測該事故情 況。就此一結果，電流比較器5輸出電流13至衰減器6之控 制輸入使其增加橫向電流IN之衰減量來減低之及為一結果 即減低加至線路驅動器2, 3之電流之全部之量。 本紙張尺度適用中國國家標準(CNS) A4規格(210 X 297公釐)And risk of damage. The drawing is simple and clear. The invention will be explained in detail with reference to Figure 1 attached below. Figure 1 is a principle display diagram of a specific embodiment of SL1c using an arrangement for overcurrent protection according to the invention. DESCRIPTION OF THE INVENTION Fig. 1 is a principle display diagram of a specific embodiment of a SLIC 1 using an arrangement for protecting an SLIC according to one of the inventions for preventing overcurrent. In a known manner, sue 1 includes connecting its own input to the respective output of a controllable current attenuator 6 and using its own output to one of the two two-line carousel lines A, B to one User station 8bis line driver 2,3. The input terminal of the current attenuator 6 is supplied with a lateral current such as a line current, a call signal, a ringing k number, etc., and is transmitted to the transmission line A and B to the user station 8 due to the line drivers 2, 3. Moreover, in a known manner, SLic includes means for detecting and cancelling any longitudinal currents on the transmission lines A, B. In the specific embodiment shown in Fig. 1, the line drivers 2, 3 are current amplifiers. In order to detect a vertical current, the line 8 and 8 are measured and achieved by comparing the device of the device 91 with a reference value by using, for example, a differential amplifier method using a voltage-to-current converter. The voltage-to-current converter 9 is connected to the line a of the transmission line using one input terminal and is connected to the reference voltage ^ using the other input terminal thereof. Under normal conditions, the silver scale of the reference paper applies the Chinese National Standard (CNS) A4 specification (210X297 mm) 546883 A7 ____- B7 V. Description of the invention (3) The voltage VI is equal to ground. The converter 9 converts the potential difference between the ground and the potential of the line a to a current 17 supplied to a first input terminal of a current amplifier 4. The voltage-to-current converter 10 uses an input terminal to connect to the line B of the transmission line. And its other round is connected to the reference voltage V2. Normally, the reference voltage V2 is a negative potential relative to VI, and the converter 10 converts the potential difference between the potential of V2 and the line b into a current 18 supplied to a second input terminal of the current amplifier 4. The current amplifier 4 has two output terminals connected to the input terminals of the respective line drivers 2, 3. The current amplifiers are suitable for outputting respective output currents 15, 16 which are in proportion to the difference between the currents 17 and μ in proportion to the longitudinal currents other than the line drivers 2, 3 on the transmission line. Currents 15, 16 are sent to line drivers 2, 3 to counteract the longitudinal currents on lines A and B. If line drivers 2, 3 are replaced by voltage amplifiers, the currents in line a and line B will be measured to determine the value of any longitudinal current. According to the present invention, a current amplifier 4 is provided with a third output terminal for outputting a current 14 corresponding to the current 15, 16 of the current amplifier 4 to the line drivers 2, 3, so as to offset the current on lines A and B. Longitudinal current. The third output terminal of the current amplifier 4 is connected to a first input terminal of a current comparator 5. A second input terminal of the current comparator 5 is connected to a reference current generator 7 which generates a reference current 19. The color test current 19 is designed to be consistent with a longitudinal current and is a higher rated maximum current supplied by SL 1C than the specified guarantee. In this way, SLIC can offset the current which is slightly higher than the longitudinal current which is consistent with the reference current 19. Therefore, the current 14 must always be better than the reference -6- This paper size applies the Chinese National Standard (CNS) A4 specification (210X297 mm) 546883 A7 B7 V. Description of the invention (4) The test current 19 is only good. The current comparator 5 uses its output terminal connected to one of the control input terminals of the current attenuator 6. At its output, the current comparator 5 generates an output current 13 when 14 > 19. When the vertical current on the transmission line is extremely high, the current 13 controls the current attenuator 6 to increase its attenuation to reduce or even block the lateral current I n. This reduces the risk of damage to the drive by reducing the lateral current. According to this example, SL 1C can guarantee a vertical current of 20 mA in normal conditions. In this case, 14> 19. In the case of an accident, the longitudinal current is > 20 mA. In order to detect the accident, the reference current 19 is preferably set to an arbitrary value of 20 mA in the longitudinal current and a current value of 24 mA, which is the maximum longitudinal current that can be driven by the line drivers 2, 3. 19 can be set to match eg 22 mA. When 14 > 19 then an accident condition was measured. When the current 14 corresponds to a longitudinal current > 22 mA, the current comparator 5 detects the accident situation. Based on this result, the current comparator 5 outputs the current 13 to the control input of the attenuator 6 to increase the amount of attenuation of the lateral current IN to reduce the sum, and as a result, it reduces the total amount of the current applied to the line drivers 2, 3. This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)