| 摘要 |
<p>PURPOSE:To enable ample color development of a heat sensitive paper while holding the maximum temperature of a heat generating element composing a thermal head by making the power waveform of a drive pulse to be applied to the heat generating element decrease from a large level at initial pulses generation. CONSTITUTION:When voltage between terminals (a) and (b) of a capacitor C becomes V2 in a time T1 after the initialization thereof. With the switch changed over to the first position, switches S2 and S4 are turned ON while switches S1, S3 and S5 OFF. A power source E and the capacitor C are connected in series to put voltages V1 and V2 together to a heat generating element r0. Under such a condition, the capacitor C is discharged and then, is charged from 0 in the opposite polarity by the power source E until the voltage to be applied to the heat generating element r0 reaches V3 after the time T passes. Then, with the switch changed over to the second position, switches S1 and S5 are turned ON while switches S2, S3 and S4 OFF, V1+V2 are applied to the heat generating element r0 in the same waveform as that in the first step position. The voltage of such a waveform causes the temperature of the heat generating element to rise very quickly.</p> |
