PURPOSE: To eliminate the influence exercised by a change in surrounding environment, and to obtain a high-reliable life testing data, by a method wherein the energizing to a heater, being an object to be tested, and the heating cycle of the heater is kept constant.
CONSTITUTION: Temperature of a heater 1, being an object to be tested, is detected by a temperature detecting element 2, and the output is inputted to a comparing means having a hysteresis. The comparing means consists of comparators 3, 4 and a flip flop circuit 5, and upper limit and lower limit signals VR1 and VR2 of the heater are applied to the comparators 3 and 4. The flip flop circuit 5 sends an energizing control signal from an output terminal Q to a control input terminal C of an energizing of the heater 1. This causes holding of a constant heating and cooling cycle occurring resulting from make-and-break energizing to the heater, being an object to be tested, and reduces the influence exercised by a change in air velocity and surrounding environment, which results in obtaining a high-reliable data, and besides, in enabling to detect deterioration such as wire-breaking.
TERADA JIROU
NITSUTA KOUJI
