| 摘要 |
PURPOSE:To enhance a recording speed, by a method wherein a supply voltage to be applied to a thermal head can be switched per heating element. CONSTITUTION:Data '1' which is common to red and black are transferred into a shift register unless white (non-printing). While, as an image information to a voltage control part 15, data for a block to be printed from now on is set, but data '1' is set only when black printing requiring a short pulse is to be conducted. As soon as a STROBE 1 turns active (H) and red/black printing of a block 1 starts, a counter circuit 15a is actuated to generate a short- pulse signal (a) required for black printing. A switching signal forming circuit 15b generates a switching signal (b) according to the STROBE 1 and the signal (a). The signal (b) is ANDed with the image information in a gate circuit 15c. In case of black ('1'), a transistor 15d has been made ON and a voltage has not been applied to a heating element for a fixed period (tsgamma+t'sgamma). A control of a long pulse by a STROBE signal is simultaneous with that of a short pulse by a switching of voltage, which allows an enhancement of a recording speed. |
