| 摘要 |
PURPOSE: To eliminate the unevenness of charging and discharging times, to hold the initial charge of a capacitor constant, and to improve the resistance value measuring accuracy of each heat generating element by charge/discharge control means for repeating charging and discharging to measure the discharge time of other heat generating element, and resistance value calculating means for calculating the resistance value of each element based on the measured result. CONSTITUTION: A charge/discharge control circuit 70 turns OFF a charge switch 59 when the counted value of a charge counter becomes T1, and simultaneously sends a charge end signal to a counter controller. The discharge time of a capacitor 57 by a first heat generating element 22) is counted similarly to the measurement of the discharge time of a reference resistor 56, and written in a RAM 43a. Similarly, the other generators 222 -22n are counted for the discharge times Td2 -Tdn , and written in the RAM 43a. The controller 43 calculates the resistance values R1Rn of the elements 221 -22n read from the RAM 43a, and writes it in the RAM 43c. |
