Patent ID: 7532940

Claim:
A transfer mechanism for transferring a target object having a mainly circular contour, the mechanism comprising: a transfer unit including a pick at a distal end for supporting the target object, and configured to supply movements to the pick in an angular direction and a rectilinear direction; an optical sensor disposed at a standby position on a route of the target object toward a destination, and configured to optically detect presence/absence of the target object on the pick; an output detecting section configured to detect a signal output from the optical sensor, when the pick supporting the target object is supplied with movements in the angular direction and the rectilinear direction at the standby position; an arithmetic section configured to calculate an angular misalignment amount Δθ of the target object in the angular direction and a rectilinear misalignment amount of the target object in the rectilinear direction, with reference to a detection value of the signal obtained by the output detecting section, a reference value of the signal, and at least one of a detection value and a reference value of a radius of the target object based on the mainly circular contour; and a controller configured to control the transfer unit to compensate for the angular misalignment amount Δθ and the rectilinear misalignment amount, when the pick is operated to transfer the target object to the destination, wherein the signal includes first and second signals output from the optical sensor when the pick supporting the target object is moved in the angular direction and the rectilinear direction, respectively, and the arithmetic section is configured to calculate the angular misalignment amount Δθ with reference to both the detection value and the reference value of the radius using formula (1), Δθ=θ1−θ0+α( R 0− R 1) (1) where θ1 denotes the detection value of the first signal, θ0 denotes the reference value of the first signal, R0 denotes the reference value of the radius, R1 denotes the detection value of the radius, and α denotes a conversion coefficient from the radius to a swing angle.