PURPOSE: To prevent deterioration at the time of changing over a recording scan density and obtain a constantly fixed recording density by adding a recording scan density change-over signal and a minimum circuit to a conventional pulse width control circuit for an electric current for recording.
CONSTITUTION: By the conventional pulse width control circuit for the current for recording, the pulse width of the current for recording, which is determined by the period of time for which an output terminal P1 is at H level, is determined as 1.1CR1 by the time constant according to a thermistor R1 and a capacitor C so that a characteristic satisfying the curve of a recording scan density of 7.7l/mm can be obtained. By setting the recording scan density change-over signal I2 at H level, the pulse width of the current for recording can be extended to 1.1C(R1+R2). By adjusting the increment 1.1CR2 of the pulse width to conform to the required pulse witdh and by obtaining the curve of a scan density of 3.85l/mm, a fixed recording density can be obtained even at the time of changing over the scan density.
SATOU KUNIO
IKEDA TAKAHISA
