US 7,321,230 B2
Rotation angle-detecting device
Masaharu Ushihara, Hirakata (Japan); and Kouji Oike, Otokuni-gun (Japan)
Assigned to Matsushita Electric Industrial Co., Ltd., Osaka (Japan)
Filed on Mar. 05, 2007, as Appl. No. 11/713,685.
Application 11/713685 is a continuation of application No. 10/511729, granted, now 7,202,659, previously published as PCT/JP2004/002593, filed on Mar. 03, 2004.
Claims priority of application No. 2003-064882 (JP), filed on Mar. 11, 2003.
Prior Publication US 2007/0152662 A1, Jul. 05, 2007
This patent is subject to a terminal disclaimer.
Int. Cl. G01B 7/30 (2006.01)
U.S. Cl. 324—207.25  [324/207.21] 22 Claims
OG exemplary drawing
 
1. A rotation angle-detecting device comprising:
a main rotator;
a first detecting rotator having contact with the main rotator, and being configured to rotate faster than the main rotator;
a first magnet located at a center of the first detecting rotator;
a first magnetic detector located on a surface spaced opposite the first magnet;
a second detecting rotator having contact with the first detecting rotator, the second detecting rotator being configured to rotate at a different speed than the first detecting rotator;
a second magnet located at a center of the second detecting rotator;
a second magnetic detector located on a surface spaced opposite the second magnet; and
a first ferromagnetic body encircling and fixed with respect to one of the first magnetic detector and the second magnetic detector and having a radius smaller than a radius of one of the detecting rotators spaced opposite said ferromagnetic body.