Patent ID: 7114933

Claim:
A potter's wheel for working pottery material, comprising: a turntable for supporting the pottery material; a motor for driving the turntable; a manipulation member to be operated by a user; a speed signal producer for producing a directive speed signal which changes as a function of an amount of operation of the manipulation member by the user; a speed detector for detecting the rotational speed of the motor and generating a detected speed signal representative of the detected speed; a speed control signal producer for producing a motor speed control signal as a function of the difference between the directive speed signal and the detected speed signal; and a motor controller for generating a motor drive signal and feeding the motor drive signal to the motor, the motor controller being capable of controlling the motor drive signal so that the speed control signal becomes zero, wherein the motor controller includes a driving circuit for generating a motor driving current to be fed to the motor, a current detector for detecting the current fed to the motor, an upper limit memory section for storing an allowable upper limit value of the electric current, a comparator for comparing the detected current with the upper limit value stored in the upper limit memory section, and a feedback circuit for feeding back the output of the comparator to the driving circuit to control the motor driving current outputted from the driving circuit.