| 摘要 |
<p>PURPOSE: To provide a sensor for controlling a heater in a thermal ink jet print head to operate over a predetermined ink jet threshold value without supplying excess power to the heater. CONSTITUTION: An optical sensor 1 is disposed to output even when its light path is partly shielded by injected ink. An output signal from the sensor 11 is input to an integrator having an amplifier 25, a capacitor 35 and a resistor 36, integrated, this integrated output is input to a high gain amplifier 40, and input to a control circuit 44. The circuit 44 controls the power to a heating element 46 so that the power becomes higher than the power threshold value starting the jet based on the input.</p> |
