US 4,907,178 A · Method for detecting a reference angular position of a rotary body

Abstract

A method of detecting a reference angular position of a rotary body. Two detectable portions are spaced apart from each about the periphery by a predetermined angle in the rotational direction thereof. Two detection signals and produced from two detectors spaced apart from each other by the same angular distance as the detectable portions in the rotational direction of the rotary body in the vicinity of the locus of the detectable portions. It is first detected that at least one of the detectors produces a detection signal and thereafter it is determined that the rotary body takes a reference angular position when both of the detectors produce the detection signals.

Claims10

Dependent claims

A method for determining a reference angular position of a rotary body on which at least two detectable portions are formed spaced apart from each other by a predetermined angle in the rotational direction thereof, by using output signals generated from two detectors spaced apart from each other by said predetemined angle in the vicinity of the locus of said detectable portions along the rotational direction of said rotary body, the output signals of the respective detectors being at a detection level upon the passage of said detectable portions comprising:

a first detection step for detecting that either one of the output signals from said detectors reaches said detection level;
a second detection step for detecting that both output signals from said detectors simultaneously reaches said detection level following the detection of said first detection step;
and
a determining step for determining that said rotary body reaches said reference angular position upon the detection by said second detection step.

1 more element

A method for determining a normal rotation of a rotary body on which at least two detectable portions are spaced apart from each other by a predetermined angle in the rotational direction thereof, using output signals generated from two detectors spaced apart from each other by said predetermined angle in the vicinity of the locus of said detectable portions along the rotational direction of said rotary body, the output signals for the respective detectors reaching a detection level upon the passage of said detectable portions comprising:

periodically sampling the levels of said output signals to obtain sample values (x,y), where x corresponds to an output level sample of one of said detectors positioned ahead of the other of said detectors in the normal rotational direction of said rotary body, and y corresponds to a detection level of said other detector;
a first storage step for storing the values (x, y) as first storage values when (x, y) are not equal to (0, 0);
a first waiting step for waiting for a state that the values (x, y) are equal to (0, 0);
a second waiting step for waiting for a state where the values (x, y) are equal to (0, 0) after the completion of said first waiting step;
and
a first determining step for determining that said rotary body has rotated in the normal direction when the values (x, y) become (1, 1) after completion of said second waiting step when said first storage values are equal to (0, 1), and for repeating said first storage step through said second waiting step until the values (x, y) become (1, 1).

3 more elements

Dependencies are inferred from the claim text.

Method for detecting a reference angular position of a rotary body

Life of this patent

Method for detecting a reference angular position of a rotary body

Life of this patent

Abstract

Claims10