US 12,092,498 B2
Absolute encoder
Shunichi Akama, Shizuoka (JP); Shiro Fukuda, Shizuoka (JP); and Yasunori Murayama, Shizuoka (JP)
Assigned to YAMAHA HATSUDOKI KABUSHIKI KAISHA, Iwata (JP)
Filed by YAMAHA HATSUDOKI KABUSHIKI KAISHA, Iwata (JP)
Filed on Jul. 15, 2022, as Appl. No. 17/866,369.
Application 17/866,369 is a continuation in part of application No. PCT/JP2021/001529, filed on Jan. 18, 2021.
Claims priority of application No. PCT/JP2020/001526 (WO), filed on Jan. 17, 2020.
Prior Publication US 2022/0364887 A1, Nov. 17, 2022
Int. Cl. G01D 5/245 (2006.01); G01D 5/241 (2006.01); G01D 5/249 (2006.01); G01D 5/347 (2006.01)
CPC G01D 5/2455 (2013.01) [G01D 5/2415 (2013.01); G01D 5/245 (2013.01); G01D 5/2497 (2013.01); G01D 5/347 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An absolute encoder for acquiring a rotation angle of a measurement target member within a mechanical angle of 360 degrees, the absolute encoder comprising:
a brake mechanism including
a rotary body including a plurality of engaging protrusions, and
an engaging pin that engages with one of the plurality of engaging protrusions;
a plurality of AB-phase-signal-detection-target portions that are arranged at equal intervals in a circumferential direction within a range of the mechanical angle of 360 degrees and that are configured to generate AB-phase signals;
a plurality of Z-phase-signal-detection-target portions, each including
a Z-phase-signal-rise-detection-target portion that generates a rise of a Z-phase signal, and
a Z-phase-signal-fall-detection-target portion that generates a fall of the Z-phase signal,
the plurality of Z-phase-signal-detection-target portions being arranged in the circumferential direction within the range of the mechanical angle of 360 degrees, such that the Z-phase-signal-rise-detection-target portions and the Z-phase-signal-fall-detection-target portions are alternately located in the circumferential direction, to thereby form
a plurality of first intervals in the circumferential direction, each between one of the Z-phase-signal-rise-detection-target portions and one of the Z-phase-signal-fall-detection-target portions that are adjacent to each other in the circumferential direction,
a plurality of second intervals in the circumferential direction, each between one of the Z-phase-signal-rise-detection-target portions and one of the Z-phase-signal-rise-detection-target portions that are adjacent to each other in the circumferential direction, and
a plurality of third intervals in the circumferential direction, each between one of the Z-phase-signal-fall-detection-target portions and one of the Z-phase-signal-fall-detection-target portions that are adjacent to each other in the circumferential direction; and
an output unit that is configured to output the AB-phase signals and the Z-phase signals, wherein
the AB-phase-signal-detection-target portions, the Z-phase-signal-rise-detection-target portions, the Z-phase-signal-fall-detection-target portions, and the rotary body integrally rotate;
the engaging protrusions of the rotary body are positioned to divide a rotation range of the rotary body into a plurality of restriction ranges; and
the plurality of Z-phase-signal-detection-target portions are so arranged that
each of the AB-phase-signal-detection-target portions is located between one of the Z-phase-signal-rise-detection-target portions and one of the Z-phase-signal-fall-detection-target portions that are adjacent to each other in the circumferential direction, and
each of the plurality of restriction ranges includes at least
one of the Z-phase-signal-rise-detection-target portions, and
one of the Z-phase-signal-fall-detection-target portions,
wherein
the first intervals in the restriction ranges are different from each other, and/or
the second intervals in the restriction ranges are different from each other, and/or
the third intervals in the restriction ranges are different from each other.