| 摘要 |
PURPOSE:To enable a heat sensitive recording having a plurality of colors or densities with a simple constitution by a method wherein a voltage impressed to the heating element of the heat sensitive printer is switched in a plurality of steps and a predetermined thyristor element is controlled to be turned ON upon the predetermined voltage. CONSTITUTION:An electric source 4 impressing a voltage to the heating elements 1a-1n is constituted with four sets of electric source circuits 41a-41d and voltages Ea-Ed of four steps are impressed by switching these circuits sequentially. At first, at a time t11a, a change-over switch 42 is switched so as to supply the voltage Ea to the heating element 1i corresponding to a picture element having the highest density and the thyristor element 2i corresponding thereto is driven to be turned ON simultaneously. In the similar manner, the heating element 1j corresponding to the picture element having the second highest density is impressed with the voltage Eb at the time t11b. Sequentially, the predetermined heating elements are driven at the times t11c, t11d and a switch 43 is opened at the time t12 to turn OFF respective thyristor elements. |
