Patent ID: 7026605

Claim:
An angle detection device for a rotational body, comprising: a scanning mirror for scanning light in an angular direction that corresponds to a rotation angle of the rotational body; a fluorescent fiber whose external peripheral surface is scanned in an axial direction by scanning light from the scanning mirror; a first light-receiving element for detecting an intensity of light emitted from one end of the fluorescent fiber and a second light-receiving element for detecting an intensity of light emitted from the other end of the fluorescent fiber; and scanning position detection means for detecting a scanning position of the scanning light in the axial direction of the fluorescent fiber on the basis of outputs of the first and second light-receiving elements; wherein the fluorescent fiber has a core layer doped with a fluorescent pigment; the fluorescent fiber has an arcuate shape; the scanning light comprises light at a wavelength whereby the fluorescent pigment can be excited to generate fluorescence; the rotation angle position of the rotational body is detected on the basis of the detected scanning position; and a beam reflecting point of the scanning mirror is located on a center of the arcuate shape of the fluorescent fiber.