| 摘要 |
<p>PURPOSE:To automatically compensate an unbalance component of Hall element by counting the output pulse corresponding to the unbalance amount of output voltage of the Hall element. CONSTITUTION:A Hall element 1 to which a current converted 2 from voltage and a magnetic field converted from measured system current by a core are inputted outputs a voltage proportional to the product of the current and magnetic field. The output voltage is amplified 4 and a voltage C which is sign- inverted by an inversion amplifier 5 is inputted by an output terminal 20. At this time, a comparator 6 outputs a voltage E at an H (L) level when the voltage C is higher (lower) than reference potential. An up/down counter 9 whose counter value is preset to be 32768 up- (down-) counts the voltage when the voltage E is at the H (L) level, and the result becomes larger (smaller) than 32768 when the polarity of the unbalance amount of the output voltage of the element 1 is positive (negative). A compensation calculation part 10 calculates the difference to find out the compensation value of unbalance components, and a variable resistance element 7 changes the resistance value with the converted 11 output voltage and makes the unbalance component of the element to be zero.</p> |
