| 摘要 |
PROBLEM TO BE SOLVED: To reduce the size of a power supply by reducing useless power consumption in a head drive circuit. SOLUTION: A print wire is driven by turning a transistor 33 connected with a head coil 59 on/off thereby supplying a drive current i to the coil 59. At the joint of the coil 59 and the transistor 33, input of a DC/DC converter 2 is connected and the output of the converter 2 is connected to the joint of a power supply 34 and the coil 59. The converter 2 clamps a high voltage being induced in the coil 59 when the transistor 33 is turned off at a constant level, e.g. 90 V, and then converts it into the voltage of the power supply 34, e.g. 35 V. Consequently, energy stored in the coil 59 is not consumed uselessly by the transistor 33 but returned back to the power supply 34 and reused. Input voltage of the converter 2 is held at the constant level by means of an initial charging circuit 4.
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