| 摘要 |
PURPOSE:To reduce a rotor starting angle speed to reduce the generated impulsive sound, by chopping the leading part of a pulse for step motor driving. CONSTITUTION:The output of a prescribed frequency division stage and the output of a prescribed frequency division stage passing through inverter 24 partially which frequency divider 4 outputs are applied to AND circuits 12 and 14 of waveform shaping circuit 6, and a stepping motor driving pulse for needle driving is applied to exclusive OR circuits 32 and 34. These circuits 32 and 34 are controlled through AND gates 16, 18, 20 and 22 and so on where the prescribed frequency division stage output of frequency divider 4 passing through inverters 30, 28 and 26 and the output of circuit 14 are applied, and the leading part of the stepping motor driving pulse output from circuits 32 and 34 is chopped by a signal of a high frequency such as 512Hz. Consequently, the starting angle speed of the permanent magnet rotor of the stepping motor is reduced, and the impulsive sound generated for starting is reduced, so that a clock with noise reduced can be obtained. |
