| 摘要 |
PURPOSE:To finely express the gradation of printing without increasing the number of LEDs by changing LED driving pulse width according to printing gradation data to change density in an one dot unit. CONSTITUTION:A printing gradation register 3 is a register holding printing gradation data and outputs the printing gradation data to a microprocessor 4. The microprocessor 4 sets the time driving an LED 12 to a timer 5 according to the printing gradation data. A drive circuit 6 outputs the time pulse set by the timer 5 to an AND circuit 8 to drive the LED 12. When the driving pulse width of the LED 12 is set to A, B, C, the luminous intensity of the LED changes to D, E, F. When the luminous intensity of the LED 12 changes, density also changes in proportion to the change of said luminous intensity and, therefore, gradation is carried out in three stages in this case by the setting of the pulse widths A, B, C. As mentioned above, by setting the time of a drive pulse to the timer 5 according to printing gradation data, gradation printing can be easily carried out. |
