Patent ID: 9641057
Date: 2017-05-02
CPC Classifications: B60K,F16H,G02B,H02K,Y10T

Claim:
1. A stepper motor for a vehicle head-up display apparatus, which has a reflector that is rotatable and reflects a display light outputted from a display device, the stepper motor comprising: a housing; an electric motor unit that is received in the housing and outputs a rotational drive force when the electric motor unit is rotated through energization of the electric motor unit; a speed reducing device that is received in the housing and has a plurality of gears, which include a final gear, wherein the speed reducing device reduces a rotational speed of rotation generated by the rotational drive force outputted from the electric motor unit through the plurality of gears; and an output shaft that is rotatably supported by the housing and outwardly extends from the housing, wherein the output shaft is rotated by the rotational drive force transmitted from the final gear to rotate the reflector, wherein: the output shaft includes: a recess is recessed in the axial direction in the base end section toward the another end portion of the rod and extends in the circumferential direction along an entire circumferential extent of the rod; the recess is located between the gear portion and the rod in a radial direction; the recess is provided only on a side of the bearing portion of the housing, at which the one end portion of the rod is located, in the axial direction; the axial intermediate section is continuously filled with the resin in a region, which extends from an outer peripheral surface of the rod to an outer peripheral surface of the axial intermediate section in the radial direction, along the entire circumferential extent of the rod; and a ratio of an entire length of the recess, which is measured in the axial direction, relative to an entire length of the plurality of gear teeth of the gear portion, which is measured in the axial direction, is set to be equal to or smaller than 0.725.