Abstract: A multiple-rotation absolute-value encoder of a geared motor, wherein the geared motor (10) reduces the rotational speed of a motor shaft (12) and takes it out from a gear shaft (14) to drive a machine device (15) in an operating range corresponding to two rotations of the gear shaft (14). The multiple-rotation absolute-value encoder (20) fitted to the geared motor (10) is made up of a gear shaft absolute value encoder (30) for detecting the absolute position of the gear shaft (14) and a load side absolute value encoder (50) having a two-pole magnet (51) and a magnetic sensor (52) rotating at a rotational speed reduced to half the rotational speed of the gear shaft (14) through the magnetic gear (40).

Abstract: A multiple-rotation absolute-value encoder of a geared motor, wherein the geared motor (10) reduces the rotational speed of a motor shaft (12) and takes it out from a gear shaft (14) to drive a machine device (15) in an operating range corresponding to the two rotations of the gear shaft (14). The multiple-rotation absolute-value encoder (20) fitted to the geared motor (10) comprises a gear shaft absolute value encoder (30) detecting the absolute position of the gear shaft (14) and a load side absolute value encoder (50) having a two-pole magnet (51) and a magnetic sensor (52) rotating at a rotational speed reduced to half the rotational speed of the gear shaft (14) through the magnetic gear (40). Since the operating range of the machine device (15) corresponds to one rotation of the two-pole magnet (51), the absolute position of the machine device (15) is determined based on an output from the magnetic sensor (52).

Abstract: An insert member (42) having an identical permeability is fitted in the circular center hole(41a) of a magnetic ring (41) which is then fitted in the circular hollow section (43a) of a fitting-over member (43) having an identical permeability. Under that state, the magnetic ring (41) is placed in a parallel magnetic field. Lines of magnetic flux passing through the magnetic ring (41) held between the insert member (42) and the fitting-over member (43) become linear without substantially inclining against the parallel magnetic field. Under that state, harmonic noise causing a deterioration in detection precision will scarcely appear in the output of a magnetic sensor for detecting the rotating magnetic field of a ring magnet (40) obtained by performing two-pole magnetization on the magnetic ring (41).

Abstract: A motor encoder is mounted on a motor shaft of a geared motor 1, and the origin position is detected by using a Z-phase signal. An absolute value encoder with a precision that allows the number of motor rotations to be determined is mounted on an output shaft 4 of a reduction gear, and the absolute rotational position thereof is detected. When the first Z-phase signal generated in conjunction with the rotation of the motor shaft 2a is obtained at startup and at other times, the mechanical starting point at which the motor shaft and output shaft are both positioned at the origin can be calculated based on the absolute rotational position of the reduction-gear output shaft obtained from the output-side absolute value encoder. Since the mechanical starting point is obtained by rotating the motor shaft a single rotation at most, the time required to calculate the mechanical starting point is short in comparison with conventional examples, and extraneous rotational movements can be avoided.

Abstract: An insert member (42) having an identical permeability is fitted in the circular center hole (41a) of a magnetic ring (41) which is then fitted in the circular hollow section (43a) of a fitting-over member (43) having an identical permeability. Under that state, the magnetic ring (41) is placed in a parallel magnetic field. Lines of magnetic flux passing through the magnetic ring (41) held between the insert member (42) and the fitting-over member (43) become linear without substantially inclining against the parallel magnetic field. Under that state, harmonic noise causing deterioration in detection precision will scarcely appear in the output of a magnetic sensor for detecting the rotating magnetic field of a ring magnet (40) obtained by performing two-pole magnetization on the magnetic ring (41).

Abstract: A motor encoder is mounted on a motor shaft of a geared motor 1, and the origin position is detected by using a Z-phase signal. An absolute value encoder with a precision that allows the number of motor rotations to be determined is mounted on an output shaft 4 of a reduction gear, and the absolute rotational position thereof is detected. When the first Z-phase signal generated in conjunction with the rotation of the motor shaft 2a is obtained at startup and at other times, the mechanical starting point at which the motor shaft and output shaft are both positioned at the origin can be calculated based on the absolute rotational position of the reduction-gear output shaft obtained from the output-side absolute value encoder. Since the mechanical starting point is obtained by rotating the motor shaft a single rotation at most, the time required to calculate the mechanical starting point is short in comparison with conventional examples, and extraneous rotational movements can be avoided.