| 摘要 |
PURPOSE:To contrive to make recording temperature uniform, by a method wherein the ambient temperature in the vicinity of a heating resistor is detected, and the period of time for which a voltage is impressed on the resistor is controlled in accordance with variations of the temperature. CONSTITUTION:On receiving an output from a detector 4 accompanying the variations of temperature, a pulse generator 3 supplies a signal with a pulse width corresponding to the output to a controlling circuit 2. Based on the signal, the circuit 2 supplies a signal to a driving circuit 5 so that the pulse width of the voltage impressed on the heating resistor 6 is larger or smaller according as the detected temperature is higher or lower, whereby the density of recorded data is maintained to be constant irrespectively of the temperature variations. In addition, the circuit 2 counts constant-period pulses generated by an oscillator 1, and limits the maximum of the pulse width of the voltage impressed on the resistor 6. Namely, when the pulse width of the voltage impressed on the resistor 6 which width is calculated on the basis of an output from a pulse generator 3 exceeds a predetermined allowable upper limit, the pulse width of the voltage impressed on the resistor 6 is set to the upper limit. Accordingly, even when the detected temperature is considerably low, the resistor 6 is prevented from being excessively heated. |
