Field of the Invention
The present invention relates to a position detection apparatus that detects a position of a target object.
Description of the Related Art
There is a known image forming apparatus that primarily transfers toner images respectively formed on a plurality of photosensitive members to an intermediate transfer belt and secondarily transfers a color image composited on the intermediate transfer belt to a recording material.
Incidentally, when the intermediate transfer belt in the image forming apparatus is deviated in a width direction that intersects perpendicularly with a belt conveying direction, color misregistration in which the toner images of the plurality of colors on the intermediate transfer belt are deviated may occur. In order to prevent generating such color misregistration, there is a known correction control that detects a deviation amount in the width direction that intersects perpendicularly with the belt conveying direction of the intermediate transfer belt and that corrects belt driving corresponding to the deviation amount.
As an apparatus that detects a deviation amount of an intermediate transfer belt, there is a proposed apparatus that is provided with a swinging arm that is in contact with an edge of the intermediate transfer belt and swings and two optical sensors that are arranged on the swinging arm so as to shift in a longitudinal direction thereof that is the conveyance direction of the intermediate transfer belt. In this belt-deviation-amount detection apparatus, the swinging arm swings corresponding to the deviation amount of the intermediate transfer belt. And a result of whether the deviation amount of the belt falls in tolerance is detected using changes of the signals from the two optical sensors on the swinging arm due to swinging (for example, see Japanese Laid-Open Patent Publication (Kokai) No. 2010-243791 (JP 2010-243791A)). Moreover, this belt-deviation-amount detection apparatus detects the deviation amount of the belt in five levels.
However, the above-mentioned conventional apparatus is easily affected by variations of the sensor positions and skew of a target object (belt), and particularly, there is a problem of erroneous detection near a boundary between adjacent deviation levels.