Focus adjustment device and method

摘要

A focus adjustment device that eliminates unnecessary driving of a shooting lens after the shooting lens has already been driven near to an in-focus position. In a focus adjustment device, information related to the defocus amount of the shooting lens is detected based on output signals corresponding to the light intensity distribution of a object image from a pair of photo-electric conversion arrays. The focus adjustment device includes a focus detection circuit to determine the confidence level of the detected information based on predetermined determination criteria and a lens driving device to drive the shooting lens based on the detected information when the information of the focus detection device is accepted as having a sufficient confidence level. However, to prevent erroneous driving of the lens, such as when the object moves out of a focusing field or when the object reverses direction, the probability of rejecting the information of the focus detection on the basis of an insufficient confidence level increases. This occurs when information indicating that the occurrence of a defocus amount exceeding a predetermined range is detected by the focus detection circuit after the shooting lens has previously been determined to have been driven within permissible parameters of an in-focus position.