Abstract: In a method for the detection of the rotational position of the rotor of a DC motor with commutator by evaluating the time development of a rotor current signal of the DC motor, said signal comprising a periodic waviness around an average value and comprising current ripples generated by commutation which are superimposed to said waviness, the rotor current signal of a current ripple detector unit (30) is supplied for detecting the current ripples of the rotor current signal. The rotor current signal is further supplied to a waviness detector unit (34) for detecting a half or full wave of the rotor current signal. The current ripple detector unit (30) is arranged to output a current ripple pulse for each detected current ripple. The waviness detector unit (34) is arranged to output a waviness pulse for each period of the waviness. The output signals of both detector units (30,34) are supplied to a logic OR unit (38) for generating a logic signal.

Abstract: In a method for the detection of the rotational position of the rotor of a DC motor with commutator by evaluating the time development of a rotor current signal of the DC motor, said signal comprising a periodic waviness around an average value and comprising current ripples generated by commutation which are superimposed to said waviness, the rotor current signal of a current ripple detector unit (30) is supplied for detecting the current ripples of the rotor current signal. The rotor current signal is further supplied to a waviness detector unit (34) for detecting a half or full wave of the rotor current signal. The current ripple detector unit (30) is arranged to output a current ripple pulse for each detected current ripple. The waviness detector unit (34) is arranged to output a waviness pulse for each period of the waviness. The output signals of both detector units (30,34) are supplied to a logic OR unit (38) for generating a logic signal.

Abstract: An office-type chair having a base, a cantilevered pedestal assembly projecting upwardly from substantially a center of the base, and a seat/back arrangement connected to an upper end of the pedestal assembly. The seat/back arrangement includes a generally horizontally enlarged seat assembly and a back assembly projecting upwardly from and adjacent a rear edge of the seat assembly. The seat/back arrangement also includes a rear tilt control mechanism for normally permitting the seat/back arrangement to be vertically tilted rearwardly against the urging of a resilient biasing element away from a normal upright position into a rearwardly tilted position. A front tilt mechanism cooperates between the pedestal assembly and the seat assembly for permitting the entire seat/back arrangement to be vertically tilted forwardly away from the normal upright position so that the seat assembly declines in a forward direction. The forward tilt mechanism is independent of the rear tilt control.