JPS573596A - Phase-controlled electrically-driven tool - Google Patents

Abstract

PURPOSE:To enable an electrically-driven tool to be used in areas having different supply frequencies from each other, by changing the clock pulse frequency of the computer which phase-controls the electric motor operating characteristics of an electrically-driven tool in proportion to the change in the supply frequency. CONSTITUTION:To a microcomputer MC6, a DC power source is supplied from a constant-voltage power circuit 5, and the output corresponding to the number of revolutions of an electric motor M1 is inputted 7 from a revolution number detector 4, as well as the synchronizing output is inputted 7 from a supply frequency detecting circuit 8. Moreover, the first and second reference time generators CPG1 and CPG2 which generate a clock pulse of, e.g. 2MHz for 50Hz and a clock pulse of, e.g. 2.4MHz for 60Hz respectively are connected to the microcomputer MC6 through a change-over switch SW2. On the other hand, the output 9 of the MC6 controls transistors Tr1 and Tr2 and a trigger circuit 10. Thereby, in either case of 50Hz or 60Hz, the number of clock pulses per half cycle of the supply frequency is the same (20000). Therefore, the same phase control can be performed according to the same program.