| 摘要 |
PURPOSE:To obtain a density control circuit capable of accurately controlling the width of a pulse to be applied corresponding to an average resistance value, by constituting a part of a means setting a frequency dividing ratio in a frequency dividing circuit determining the width of the pulse to be applied of a thermal head of a switch performing ON/OFF selection corresponding to the average resistance value of the thermal head. CONSTITUTION:A frequency dividing circuit 3 divides the frequency of a fundamental clock on the basis of a frequency dividing ratio set by a frequency dividing ratio setting means. The frequency dividing ratio setting means is constituted of a computer being a part thereof and switches SW1-SW4 being the remainder. For example, the frequency dividing ratio is set by the input of 8 bits (BIT 0-8) and upper rank 4 bits are set by the order from the computer and lower rank 4 bits are set by the switches SW1-SW4. The frequency dividing ratio of upper rank four bits by the computer is determined on the basis of temp. information from the thermistor provided to a thermal head 6. The switches SW1-SW4 determining the frequency dividing ratio of lower rank 4 bits are set on the basis of the magnitude of the average resistance value of heat generating resistors displayed on the thermal head 6. |
