Patent ID: 6014205
Filing Date: 2000-01-11
Classification: G02B,H04N

Abstract:
A position sensor for a transmission type optical deflector, comprising:a prism holder supported by a yoke member to rotate about a principal axis through an elastic member;a wedge-shaped transmission prism provided on said prism holder to transmit and refract light;a coil and a permanent magnet which are provided on said prism holder and said yoke member, respectively, to produce a rotational motion of said prism holder in the forward and reverse directions about said principal axis via electromagnetic operation;a reflection layer which is coated on a surface of said wedge-shaped transmission prism other than the transmission portion thereof through which the light can pass;a light emitter for emitting collimated light onto said reflection layer; andan incident position detector for receiving the light reflected by said reflection layer and detecting the incident position of the light thereon,wherein said wedge-shaped transmission prism is partly cut away at the thicker portion thereof so that the center of gravity of said wedge-shaped transmission prism is substantially the same as said principal axis in which said principal axis appears as a point and said wedge-shaped transmission prism appears as a wedge-shape in section, and said reflection layer is formed on an incident or emission surface of the thinner portion of said wedge-shaped transmission prism that is opposed to said cut-away portion.