| 摘要 |
PURPOSE:To simply express medium contrast faithful to the original picture by combining the stepwise control of heat value and the control of the recording area of a pixel. CONSTITUTION:At the time of printing, the image signal of one line to be printed next is read from a frame memory 23 to be written in a line memory 24 and sent to a medium contrast control circuit 25 to be converted to temp. data and printing time data, for example, by designating one of temp. data of five stages and one of printing time data of several stages and both data are respectively sent to a temp. setting circuit 26 and a printing time setting circuit 27. The circuit 26 stepwise controls the power supplied to each heating element of a thermal head 10 corresponding to the temp. data of each pixel and the circuit 27 controls the heating time of each heating element corresponding to the printing time data of each pixel. A printing time is determined with due regard for the recording area of the pixel and the moving speed of thermal recording paper 13 and the thermal recording paper is moved in a main scanning direction at constant speed by a roller 30. By this constitution, medium contrast can be expressed while recording density and a recording area are stepwise changed corresponding to an image signal. |
