Chopped Current Circuit - Resistance Compensated Flight Time
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-26
When a print actuator coil is energized, much of the energy is dissipated as heat, thereby increasing the printer temperature. The increased temperature causes thermal expansion of the print actuator parts and also increases the coil resistance. While the thermal expansion of the print actuator parts causes a decrease in the flight time of the actuator, the increased coil resistance causes an increase in the flight time. In general, the effects of increased coil resistance do not completely offset the effects of thermal expansion. Consequently, as the printer heats up, the flight time decreases. A new print actuator design adds an external resistor to a chopped current circuit which powers the actuator coil. The added resistor is located near the actuator coil to provide temperature compensation.