| 摘要 |
PURPOSE:To simplify the wiring structure and while enable application of the optimal power by measuring the resistances of all heating elements and averaging them by providing a means for detecting the current flowing through each element and a means for obtaining the resistance of all heating elements on the basis of the detected current levels. CONSTITUTION:A resistor 5 for detecting a current having a known resistance (r) is arranged between a power source 3 and a heating element. A/D converters, 6, 7 digitize the potential across each resistor 5 and transmits the digitized values to a CPU 2. The CPU 2 transmits data for driving only a heating element 1a to a data drive section 4 so as to drive the power source 3. The CPU 2 acquires the potential across the resistor 5 for detecting the current from the A/D converters 6, 7 and calculates the resistance Ra of the heating element 1a on the basis of said potential. The CPU 2 repeats the operation and calculates the resistance Ra, Rb,...Rn of all heating elements 1a, 1b,...1n. Then the CPU 2 averages the resistances of all heating elements. On the basis of said average resistance, the CPU 2 controls to apply an optimal power onto the heating element thus driving the heating element. |
