Abstract: A thermoplastic resin composition improved in terms of prevention of mold contamination, comprising the following components (A) to (G):component (A): 55 to 75% by weight of a propylene-ethylene block copolymer including a propylene homopolymer moiety having a melt flow rate of 15 to 50 g/10 min. and an isotactic pentad fraction of at least 0.97, said block copolymer having a melt flow rate of 10 to 30 g/10 min. and an ethylene content of 2 to 6% by weight,component (B): 0 to 10% by weight of an ethylene-propylene copolymer rubber having a melting temperature of 30.degree. to 60.degree. C. and a melt flow rate of 0.2 to 2 g/10 min.,component (C): 5 to 15% by weight of an ethylene-.alpha.-olefin copolymer rubber having a melting temperature of 60.degree. to 100.degree. C. and a melt flow rate of 0.3 to 2 g/10 min.,component (D): 15 to 25% by weight of a talc having an average particle diameter of up to 5 .mu.m and a specific surface area of at least 3.5 m.sup.

Abstract: Method and apparatus of controlling the revolving speed of a rotary body to be rotated at the predetermined number of revolution corresponding to the reference or first signal F.sub.1. The rotary body equipped with an alternating current generator which generates a frequency signal or third signal F.sub.3 in proportion to the number of revolution thereof. During operation, the signal F.sub.3 being compared with the signal F.sub.1, if the deviation of the signal F.sub.3 from the signal F.sub.1 is within tolerance, a second variable signal F.sub.2 is swept to coincide the same with the signal F.sub.3 and further to coincide with the first signal F.sub.1 while maintaining the coincidence of the second and third signals thereby to resume the number of revolution of the rotary body to that corresponding to the reference signal.