| 摘要 |
<p>PURPOSE:To improve sensitivity of trimming of a thick film type thermal head in a high image quality printer such as a full color printer and to realize trimming with high sensitivity. CONSTITUTION:The value of resistance of a heat-generating resistive element is measured by means of a measuring device 30 at every bit or every half bit set by a multiplexer relay 40 of the resistive element of a thermal head 70 wherein the dimension of the width is made at most 50mum. The measured value is compared with the value within a specified region of the aimed value of resistance and a short high pressure pulse with 20 nano sec of a voltage in accordance with the difference between the aimed region, is applied on the resistive element to decrease the value of resistance of the heat-generating resistive element. In a high voltage pulse generator, a resistor with a low value of resistance is inserted in parallel with the resistance of the resistive element of the thermal head and when a control apparatus 10 outputs a control signal to a pulse generator 20, the voltage charged in a condenser is discharged through a relay to generate a short pulse of at most 20 nano sec and the sensitivity of trimming is improved and trimming being suitable for the use of high gradation is achieved.</p> |
